JP2009224045A - Fuel cell system - Google Patents

Abstract

The present invention provides a fuel cell system capable of adjusting the amount of water moving from the outlet side of one gas flow path to the inlet side of the other gas flow path via a membrane electrode assembly. The purpose is to do.
A fuel cell stack is formed by stacking unit fuel cells having a counter flow channel. Coolant passages 15a, 15b, and 15c are provided in the plane of the unit fuel cell 11, respectively. The coolant passages 15a, 15b, and 15c are communicated with the coolant passages 50a, 50b, and 50c, respectively. Heat exchangers 53 and 54 are provided in the coolant passages 50a and 50c, respectively.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system.

  2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-184428, a fuel cell having a so-called counter flow channel in which gas flows of an anode and a cathode are opposed to each other is known. The membrane electrode assembly (or electrolyte membrane) provided in the fuel cell exhibits good electrical characteristics in a moderately wet state. Moreover, it is preferable that power generation is performed in a state where the whole membrane electrode assembly is moistened more uniformly. According to the counter flow channel, it is possible to create a flow of water that circulates inside the fuel cell and distribute the water in a well-balanced manner inside the fuel cell. Thereby, said request | requirement can be satisfy | filled.

  Specifically, according to the counter flow channel, the cathode gas channel and the anode gas channel face each other through the membrane electrode assembly so that the flow directions of these gases are reversed. Therefore, in the counter flow channel, the cathode gas channel inlet side and the anode gas channel outlet side face each other, and the cathode gas channel outlet side and the anode gas channel inlet side face each other.

  When the fuel cell generates electricity, water is generated at the cathode. The gas (cathode gas) in the cathode gas flow path flows while containing this generated water. For this reason, the humidity on the outlet side of the cathode gas flow path becomes relatively high, and the humidity difference between the cathode and the anode becomes large at this position. When there is a humidity difference between the cathode and the anode, water moves to the low humidity side via the membrane electrode assembly. Therefore, in the conventional fuel cell, water actively moves from the outlet side of the cathode gas passage to the inlet side of the anode gas passage through the membrane electrode assembly.

  The water that has moved to the inlet side of the anode gas flow path is taken away by the anode gas flowing through the position. In other words, the anode gas is humidified by the water that has moved to the inlet side of the anode gas flow path. In the process in which the humidified anode gas flows downstream of the anode gas flow path, moisture contained in the anode gas is supplied to the membrane electrode assembly.

  Similarly, the anode gas flows while containing moisture in the anode gas flow path. Therefore, the humidity on the outlet side of the anode gas channel is relatively high, and the humidity difference between the anode and the cathode is large on the outlet side. As a result, water moves from the outlet side of the anode gas channel to the inlet side of the cathode gas channel, and the cathode gas is humidified at the inlet portion of the cathode gas channel. In the process in which the humidified cathode gas flows in the cathode gas flow path, moisture in the cathode gas is supplied to the membrane electrode assembly. As described above, according to the counterflow channel structure, it is possible to efficiently humidify the membrane electrode assembly using the generated water accompanying power generation.

JP 2002-184428 A JP 2001-43871 A JP 2001-118588 A JP-A-9-245809

  As described above, the gas channel outlet from the gas channel outlet is made to face the gas channel outlet having a relatively high humidity and the gas channel inlet having a relatively low humidity through the membrane electrode assembly. Water can be moved towards the entrance.

  As described above, there is a demand to make the amount of water moving between the gas flow paths via the membrane electrode assembly (also referred to as water movement amount) as close as possible to an appropriate amount without excess or deficiency. For example, if the fuel cell is used in an environment that is relatively easy to dry, in addition to the amount of water movement obtained as a result of facing the outlet and the inlet of the gas flow path described above, a larger amount of water is used. Situations where you want to move are also assumed. Therefore, the inventors of the present application have conducted an intensive study to satisfy such a demand, and as a result, have come up with an effective method capable of adjusting the amount of water movement.

  The present invention has been made to solve the above problems, and the amount of water that moves from the outlet side of one gas flow path to the inlet side of the other gas flow path through the membrane electrode assembly An object of the present invention is to provide a fuel cell system capable of adjusting the above.

In order to achieve the above object, a first invention is a fuel cell system,
A membrane electrode assembly having a catalyst layer on both sides of the electrolyte membrane, a first gas channel provided in contact with one surface of the membrane electrode assembly, and in contact with the other surface of the membrane electrode assembly A fuel cell, wherein an inlet side portion of the first gas channel and an outlet side portion of the second gas channel are opposed to each other with the membrane electrode assembly interposed therebetween, ,
An area on the inlet side of the first gas flow path on the surface on the first gas flow path side of the fuel cell, and an area on the outlet side of the second gas flow path on the surface on the second gas flow path side of the fuel cell. A first refrigerant passage having an inlet and having a refrigerant flowing therein during power generation of the fuel cell;
The fuel cell is provided in a central region of at least one of the first gas flow path side surface and the second gas flow path side surface, and includes an inlet different from the inlet of the first refrigerant passage. A second refrigerant passage through which refrigerant flows during power generation of the fuel cell;
Refrigerant supply means for supplying refrigerant to the respective inlets of the first and second refrigerant passages;
An adjustment mechanism capable of adjusting the temperature or flow rate of the refrigerant flowing into the inlet of the first refrigerant passage independently of the temperature or flow rate of the refrigerant flowing into the inlet of the second refrigerant passage;
It is characterized by providing.

The second invention is the first invention, wherein
Shortage determination means for determining whether or not the amount of water movement to the inlet side portion of the first gas flow path is insufficient;
If it is determined by the shortage determining means that the amount of water movement is insufficient, the temperature of the refrigerant flowing into the inlet of the first refrigerant passage is decreased, and / or the flow rate of the refrigerant is increased. Cooling control means for controlling the adjusting mechanism;
It is characterized by providing.

The third invention is the second invention, wherein
An inlet-side humidity acquisition means for acquiring, by measurement or estimation, a first gas channel inlet humidity that represents the humidity of the inlet side portion of the first gas channel;
The deficiency determining means determines that the amount of water movement to the inlet side portion of the first gas channel is insufficient when the humidity at the inlet of the first gas channel is below a predetermined lower limit value. And

Moreover, 4th invention is 2nd invention.
Water movement amount acquisition means for acquiring a water movement amount from the outlet side portion of the second gas flow path toward the inlet side portion of the first gas flow path through the electrolyte membrane;
The shortage determination means determines that the amount of water movement to the inlet side portion of the first gas channel is insufficient when the water movement amount acquired by the water movement amount acquisition means falls below a predetermined lower limit value. It is characterized by doing.

The fifth invention is the fourth invention, wherein
The water movement amount acquisition means is
A gas flow path environment acquisition means for measuring or estimating the humidity, temperature and pressure of the inlet side portion of the first gas flow path and the humidity, temperature and pressure of the outlet side portion of the second gas flow path;
Water movement characteristics storing water movement characteristics that define the relationship between the environment around the electrolyte membrane and the amount of water movement from the second gas flow path side surface of the electrolyte membrane to the first gas flow path side surface Storage means;
Using the acquired value acquired by the gas flow path environment acquiring unit, according to the water transfer characteristic, an estimation calculation unit that estimates and calculates a water movement amount;
It is characterized by including.

The sixth invention is the invention according to any one of the second to fifth inventions,
Inlet-side humidity acquisition means for acquiring, by measurement or estimation, a first gas-channel inlet humidity representing the humidity of the inlet-side portion of the first gas channel;
Outlet side humidity obtaining means for obtaining, by measurement or estimation, a second gas passage outlet humidity representing the humidity of the outlet side portion of the second gas passage;
Environmental determination means for determining whether a difference between the first gas flow path inlet humidity and the second gas flow path outlet humidity is greater than a predetermined determination value;
The cooling control means controls the adjustment mechanism when it is determined that the amount of water movement is insufficient by the shortage determination means and the difference is determined to be greater than the determination value by the environment determination means. It is characterized by doing.

The seventh invention is the invention according to any one of the first to sixth inventions,
Excess determination means for determining whether the amount of water movement to the inlet side portion of the first gas flow path is excessive;
If it is determined by the shortage determining means that the amount of water movement is excessive, the temperature of the refrigerant flowing into the inlet of the first refrigerant passage rises and / or the flow rate of the refrigerant decreases. A temperature rise control means for controlling the adjustment mechanism;
It is characterized by providing.

Further, an eighth invention is the invention according to any one of the first to seventh inventions,
The membrane electrode assembly has a specific portion sandwiched between an inlet side portion of the first gas flow channel and an outlet side portion of the second gas flow channel in a plane as compared to a central portion in the plane. The water is easy to permeate in the thickness direction.

Further, a ninth invention is the invention according to any one of the first to eighth inventions,
The specific portion sandwiched between the inlet side portion of the first gas flow path and the outlet side portion of the second gas flow path in the plane of the membrane electrode assembly is a central side in the plane of the membrane electrode assembly. Compared with a part, the increase amount of the water permeation amount with respect to the increase amount of the ambient humidity per unit area is large.

  According to the first invention, since the temperature of the refrigerant in the first refrigerant passage can be adjusted, the region where the inlet side portion and the outlet side portion of the first and second gas flow paths are opposed to each other (opposing region). The humidity of the gas flowing through can be changed to a desired value. In the membrane electrode assembly, the water permeation characteristics change according to the surrounding humidity environment, and the higher the surrounding humidity, the more water permeates. According to the first invention, the water permeation characteristics of the membrane electrode assembly in the facing region can be changed as necessary, and the amount of water moving through the membrane electrode assembly in the facing region can be adjusted.

  According to the second invention, it is determined whether or not the amount of water movement to the inlet side portion of the first gas channel is insufficient, and the inlet side of the first and second gas channels is determined according to the determination result. The region where the portion and the outlet side portion are located opposite to each other (opposing region) can be made low temperature. Thereby, the amount of water movement can be increased when necessary, and the amount of water movement can be made close to a suitable value.

  According to the third invention, the humidity of the inlet side portion of the first gas flow path is monitored, and when the humidity of the inlet side portion is excessively reduced and an increase in the amount of water movement becomes an urgent matter, The movement amount can be increased quickly.

  According to the fourth aspect of the invention, it is possible to acquire information on the water movement amount itself, accurately determine whether or not the water movement amount is insufficient, and adjust the water movement amount inside the fuel cell.

  According to the fifth invention, information (specifically, humidity, temperature, pressure) regarding the environment of the region (opposite region) where the inlet side portion and the outlet side portion of the first and second gas flow passages are opposed to each other. Based on this, it is possible to grasp the amount of water movement by estimation.

  According to the sixth invention, based on the difference between the humidity of the inlet side portion of the first gas flow path and the humidity of the outlet side portion of the second gas flow path, it is ensured that water movement can be promoted. After grasping, control for increasing the amount of water movement can be performed.

  According to the seventh invention, when it is determined that the amount of water movement is excessive, the temperature of the region (opposite region) where the inlet side portion and the outlet side portion of the first and second gas flow paths are opposed to each other is increased. Can be made. Thereby, the amount of water movement can be quickly reduced when necessary, and the amount of water movement between the anode and the cathode in the facing region can be brought close to a suitable value.

  According to the eighth invention, the configuration of the membrane electrode assembly is devised to move from the outlet side of one gas flow path to the inlet side of the other gas flow path via the membrane electrode assembly (or electrolyte membrane). You can increase the amount of water.

  According to the ninth aspect of the present invention, a great effect of promoting water movement can be obtained by devising the configuration of the membrane electrode assembly even if the surrounding humidity rise is small.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining the configuration of the system according to the first embodiment of the present invention. The system shown in FIG. 1 includes a fuel cell stack 10. The fuel cell stack 10 is formed by alternately laminating a plurality of membrane electrode assemblies 12 and a plurality of current collector plates (both not shown). This current collector plate is provided with a gas flow path and a coolant flow path, and functions as a separator that separates two adjacent membrane electrode assemblies 12. In the present embodiment, a structure constituted by one membrane electrode assembly 12 and a pair of separators sandwiching the membrane electrode assembly 12 is considered as one unit fuel cell 11. The fuel cell stack 10 is configured by stacking a plurality of unit fuel cells 11.

(Details of configuration of unit fuel cell 11)
The configuration of the unit fuel cell 11 will be described with reference to FIGS. FIG. 2 is a diagram showing a stacked structure of the unit fuel cell 11 of the present embodiment. Specifically, FIG. 2 is a cross-sectional view when one of the unit fuel cells 11 is cut in the stacking direction. FIG. 2 shows the membrane electrode assembly 12 and gas flow paths 13 and 14 (shown simply by arrows for convenience) located on both surfaces thereof.

  The membrane electrode assembly 12 is obtained by integrating electrode catalyst layers 12b and 12c on both surfaces of a solid polymer electrolyte membrane 12a (hereinafter also simply referred to as an electrolyte membrane 12a). The electrode catalyst layer 12b is formed as an anode electrode catalyst layer, and the electrode catalyst layer 12c is formed as a cathode electrode catalyst layer. Furthermore, a gas diffusion layer (not shown) made of a carbon sheet or the like is integrated with each surface of the membrane electrode assembly 12.

  Although not shown in FIG. 2, separators (not shown) are respectively located on the upper and lower surfaces of the membrane electrode assembly 12. This separator has a groove extending along the surface on the surface in contact with the membrane electrode assembly 12. By laminating the separator and the membrane electrode assembly 12, this groove can be made to function as a groove-like gas flow path extending over the surface of the membrane electrode assembly 12. This groove-like gas flow path is the gas flow paths 13 and 14. Hereinafter, the gas flow path 13 is also referred to as an anode gas flow path 13, and the gas flow path 14 is also referred to as a cathode gas flow path 14.

  The gas flow path 13 is used to circulate a fuel gas containing hydrogen (in this embodiment, hydrogen gas) in the plane of the membrane electrode assembly 12. The gas flow path 14 is used to circulate an oxidizing gas containing oxygen (air in this embodiment) in the plane of the membrane electrode assembly 12.

  In FIG. 2, the arrows indicating the respective gas flow paths indicate the directions in which the gas flows in the respective gas flow paths. In the present embodiment, as shown in FIG. 2, the flow direction of the fuel gas in the gas flow path 13 and the flow direction of the oxidizing gas in the gas flow path 14 are opposite to each other with the membrane electrode assembly 12 interposed therebetween. Become. Thus, the unit fuel cell 11 in the present embodiment has a so-called counter flow channel structure.

  Note that the shape and configuration of the gas flow path realizing the counter flow flow path are not limited to the groove-shaped flow path described in the present embodiment. For example, a porous layer made of a conductive material may be provided between the separator and the membrane electrode assembly 12, and the gas flow path may be formed by continuous pores in the porous layer.

  3A and 3B are plan views of the unit fuel cell 11. FIGS. 3A and 3B show a state in which the unit fuel cell 11 is viewed from the direction of the arrow A in FIG. 2 (that is, the upper side in the drawing). FIG. 3A shows a state in which the gas flow paths 13 and 14 extend in the plane of the membrane electrode assembly 12. FIG. 3B is a diagram showing coolant passages 15a, 15b, and 15c (shown by arrows for convenience) extending along the surface direction of the membrane electrode assembly 12 with the gas passages 13 and 14 omitted. . The coolant passages 15a, 15b, and 15c are located outside the gas passages 13 and 14 when viewed in the stacking direction, and both cross three-dimensionally.

  In FIG. 3A, the gas flow path 13 is located on the front side of the sheet with the membrane electrode assembly 12 interposed therebetween (indicated by solid arrows), and the gas flow path 14 is located on the back side of the sheet ( (Indicated by dashed arrows). Precisely, a separator exists on the front side of the paper surface of FIG. 3A, and a groove-like gas flow path 13 is formed on the surface of the separator on the back surface side (that is, the surface in contact with the membrane electrode assembly 12). ing. More precisely, there is another separator on the back side of the paper surface of FIG. 3A, and a groove-like gas channel is formed on the front surface of the separator (that is, the surface in contact with the membrane electrode assembly 12). 14 is formed.

  As shown in FIG. 3 (a), the gas flow path 13 branches into a plurality within the plane of the unit fuel cell 11, and merges at one place on each of the inlet side and the outlet side (FIG. 3 (a)). A gas channel inlet 13a on the lower right side and a gas channel outlet 13b on the lower left side in FIG. Similarly to the gas flow path 13, the gas flow path 14 is branched into a plurality of parts within the plane of the unit fuel cell 11, and merges at one place on each of the inlet side and the outlet side (FIG. 3 ( a) A gas flow path inlet 14a on the lower right side and a gas flow path outlet 14b on the lower left side in FIG. 3 (a).

  In the first embodiment, the region in which the unit fuel cell 11 is viewed in the plane direction is considered to be divided into three regions shown in FIG. 3B (regions separated by broken lines in FIG. 3). Hereinafter, these three areas are also referred to as an A area, a B area, and a C area in order from the left side of FIG. The area A is an area where the outlet side portion of the gas flow channel 13 and the inlet side portion of the gas flow channel 14 face each other. The region B is a central region of the unit fuel cell 11. The region C is an area where the inlet side portion of the gas flow path 13 and the outlet side portion of the gas flow path 14 are opposed to each other.

  In the first embodiment, as shown in FIG. 3B, three independent coolant passages (coolant passages 15a, 15b, 15c) are provided in the plane of one unit fuel cell 11. Specifically, in the present embodiment, through-holes extending in the A, B, and C regions are provided in each of the separators located on the front side and the back side in FIG. These through holes are used as the coolant passages 15a, 15b, and 15c, respectively. The gas flow paths 13 and 14 are formed on both sides of the separator, and the coolant passages 15a, 15b and 15c are formed on the inside of the separator, respectively.

  The inlets of the respective coolant passages are respectively provided on the upper end surface of the separator in FIG. The outlets of the respective coolant passages are respectively provided on the lower end surface of the separator in FIG. As described above, the coolant passage 15a extends on the A region, the coolant passage 15b extends on the B region, and the coolant passage 15c extends on the C region. As a result, the A, B, and C regions are each cooled.

  In FIG. 3, the flow of the cooling liquid to each of the A, B, and C regions is indicated by arrows directed downward in the drawing. In the following description, the temperature of the coolant flowing out of the coolant passage 15a is ta, the temperature of the coolant flowing out of the coolant passage 15b is tb, the temperature of the coolant flowing out of the coolant passage 15c is tc, Call each one.

  When the fuel cell stack 10 is configured, the gas channel inlets 13a and 14a, the gas channel outlets 13b and 14b of the individual unit fuel cells 11, and the inlets and outlets of the coolant passages 15a, 15b and 15c are respectively The fluids are grouped into separate manifolds (anode gas supply manifold, cathode gas supply manifold, anode gas discharge supply manifold, cathode gas discharge manifold) for each type of fluid.

  In the first embodiment, the fuel cell stack 10 includes six coolant manifolds independent of each other. In FIG. 3B, for convenience of explanation, the coolant supply manifolds 18a, 18b, and 18c and the coolant discharge manifolds 18e, 18d, and 18f are virtually shown by broken lines. These six coolant manifolds are connected to the inlets and outlets of the coolant passages 15a, 15b, and 15c of each unit fuel cell 11 while extending in the stacking direction of the unit fuel cells 11, that is, the depth direction in FIG. ing.

  Specifically, for each unit fuel cell 11, the inlet of the coolant passage 15a and the coolant supply manifold 18a, the inlet of the coolant passage 15b and the coolant supply manifold 18b, the inlet of the coolant passage 15c and the coolant The supply manifolds 18c communicate with each other. Further, for each unit fuel cell 11, the outlet of the coolant passage 15a and the coolant discharge manifold 18d, the outlet of the coolant passage 15b and the coolant discharge manifold 18e, and the outlet of the coolant passage 15c and the coolant discharge manifold 18f are provided. However, they communicate with each other.

  In addition, the separator provided with the various gas flow paths and the coolant passage described above can be manufactured using a conventionally known technique. For example, a metal flat plate may be prepared, grooves may be formed on both sides of the flat plate to form a gas flow path, and a through hole extending in the surface direction may be formed inside the flat plate to form a coolant passage. Moreover, you may use the separator of the multilayered structure which laminated | stacked the flat plate which has a through-hole of various shapes in the surface as conventionally well-known (for example, 3 sheets).

  In addition, a technique in which a plurality of unit fuel cells are stacked to form a fuel cell stack, a manifold is provided in the fuel cell stack, and each gas flow path and each coolant passage are merged is already known. Therefore, detailed description thereof will not be given here.

(Details of system configuration)
The system configuration of the first embodiment will be described using FIG. 1 again. An oxidant gas supply passage 17 and an oxidant gas discharge passage 16 communicate with the fuel cell stack 10. The oxidizing gas supply passage 17 communicates with the cathode gas supply manifold, and the oxidizing gas discharge passage 16 communicates with the cathode gas discharge manifold. The oxidizing gas supply passage 17 communicates with the compressor 20. The compressor 20 can supply the air sucked through the air filter 22 to the fuel cell stack 10 via the oxidizing gas supply passage 17.

  The air supplied from the oxidizing gas supply passage 17 to the fuel cell stack 10 is distributed to the gas flow path 13 provided in each of the stacked unit fuel cells 11 via the cathode gas supply manifold described above. The air distributed in this way flows through the inside of each unit fuel cell 11 along the surface of the membrane electrode assembly 12 on the cathode side, and then passes through the cathode gas discharge manifold described above to oxidize gas. It is discharged from the discharge passage 16.

  A fuel gas supply passage 24 and a fuel gas discharge passage 26 communicate with the fuel cell stack 10. A hydrogen tank 30 communicates with the fuel gas supply passage 24 via an adjustment valve 28. According to this configuration, by adjusting the opening degree of the adjustment valve 28, hydrogen gas having a desired pressure can be supplied to the fuel cell stack 10.

  The hydrogen gas supplied to the fuel cell stack 10 is distributed to the gas flow paths 14 included in each of the stacked unit fuel cells 11 via the anode gas supply manifold described above. The hydrogen gas supplied to the anode side flows along the anode side surface of the membrane electrode assembly 12 inside each unit fuel cell 11, and then passes through the anode gas discharge manifold described above. It is discharged from the discharge passage 26.

(Details of cooling system)
A coolant passage 50 is further connected to the fuel cell stack 10. In the middle of the coolant passage 50, a radiator 51 and a pump 52 are connected. When the pump 52 is driven, a coolant (referred to as Long Life Coolant (also referred to as LLC)) circulates in the coolant passage 50. The coolant passage 50 branches into coolant passages 50 a, 50 b, 50 c on the upstream side of the fuel cell stack 10.

  The coolant passages 50 a, 50 b and 50 c are connected to the respective coolant manifolds of the fuel cell stack 10. Specifically, regarding the coolant passage 50a, the coolant passage 50a upstream side → the coolant supply manifold 18a → the coolant passage 15a of the unit fuel cell 11 → the coolant discharge manifold 18d → the coolant passage 50a downstream side in this order. They communicate. Therefore, the coolant flowing from the upstream side of the coolant passage 50a is first distributed from the coolant supply manifold 18a to the coolant passage 15a of each unit fuel cell 11, and then the A of each unit fuel cell 11 is transferred. It flows along the area. The coolant is then collected in the coolant discharge manifold 18d and flows out downstream of the coolant passage 50a. In FIG. 1, the inflow and outflow states of the coolant with respect to the fuel cell stack 10 are also represented by arrows pointing downward in the drawing.

  Similarly, the coolant passages 50b and 50c communicate with the coolant supply manifolds 18b and 18c and the coolant discharge manifolds 18e and 18f, respectively. Accordingly, the coolant flowing through the coolant passages 50b and 50c is distributed from the coolant supply manifolds 18b and 18c to the coolant passages 15b and 15c of the individual unit fuel cells 11, respectively. The coolant flowing into the coolant passages 15b and 15c flows through the B and C regions of the unit fuel cells 11, respectively, and then merges with the coolant discharge manifolds 18e and 18f to cool again. It flows out to each of the liquid passages 50b and 50c. On the downstream side, the coolant passages 50 a, 50 b, and 50 c join again and connect to the radiator 51.

  As described above, in the present embodiment, the coolant passage 50 is branched in the middle to become the coolant passages 50a, 50b, 50c, and these three coolant passages are the coolant passages 15a, 15a, 15b of the individual unit fuel cells 11. It communicates with 15b and 15c individually. More specifically, in the first embodiment, the coolant passages 15a and 15b of the individual unit fuel cells 11 are joined by joining the upstream and downstream sides via the coolant passages 50a, 50b, and 50c. 15c are connected in parallel with each other. According to the present embodiment, with such a configuration, the coolant in the coolant passages 15a, 15b, and 15c are in an independent relationship with respect to temperature and flow rate.

  The system of the first embodiment includes heat exchangers 53 and 54 in the coolant passages 50a and 50c, respectively. The heat exchanger 53 can independently adjust the temperature of the coolant in the coolant passage 50a, and the heat exchanger 54 can independently adjust the temperature of the coolant in the coolant passage 50c. According to such a configuration, the temperature of the coolant in the coolant passages 50a and 50c is made different from the temperature of the coolant in the coolant passage 50b by appropriately adjusting the outputs of the heat exchangers 53 and 54. be able to.

  If the flow rate of the pump 52 is increased, the circulation amount of the coolant in the entire coolant passage 50 is also increased. In this case, the temperature of the coolant can be changed for all the coolant passages 50a, 50b, and 50c. Therefore, if the adjustment of the coolant temperature by the heat exchangers 53 and 54 and the flow rate adjustment of the pump 52 are used in combination, the temperature of the coolant in each of the coolant passages 50a, 50b and 50c is set to a desired value. It is possible to adjust.

  According to the cooling system of the system of the present embodiment described above, the temperature of the coolant flowing through the coolant passages 15a, 15b, 15c of the individual unit fuel cells 11 in the fuel cell stack 10 can be adjusted independently. Can do. Therefore, for example, the coolant in the coolant passages 15a and 15c is set to a temperature different from the coolant in the coolant passage 15b, and the temperatures of the A and C regions and the temperatures of the B regions in one unit fuel cell 11 Can be made different. Moreover, the temperature of the coolant in the coolant passages 15a and 15c can be made different to cool the regions A and C to different temperatures.

  Normally, during power generation, the temperature in the unit fuel cell 11 is made as uniform as possible throughout the entire area by the coolant. When realizing such a state in the present embodiment, the heat exchangers 53 and 54 are stopped, and the coolant in the coolant passages 15a, 15b, and 15c is set to the same temperature. Accordingly, the unit fuel cell 11 can be cooled so that the entire in-plane region (that is, all of the A, B, and C regions) has a substantially uniform temperature.

(System instrument etc.)
As shown in FIG. 1, the system of the present embodiment includes a pressure gauge 36 and a dew point gauge 38 in the oxidizing gas supply passage 17. A pressure gauge 40 is disposed in the oxidizing gas discharge passage 16. According to the former pressure gauge 36 and dew point meter 38, the pressure and humidity at the inlet (gas passage inlet 13a) of the gas passage on the anode side of the unit fuel cell 11 can be detected. According to the latter pressure gauge 40, the pressure at the outlet (gas passage outlet 13b) of the gas passage on the cathode side of the unit fuel cell 11 can be detected.

  The system of the present embodiment further includes a pressure gauge 42 and a dew point meter 44 disposed in the fuel gas supply passage 24, and a pressure gauge 46 disposed in the fuel gas discharge passage 26. According to these instruments, the pressure and humidity at the anode side inlet (gas channel inlet 14a) of the unit fuel cell 11 and the pressure at the anode side outlet (gas channel outlet 14b) can be detected.

  In addition, the system of the present embodiment includes thermometers 55, 56, and 57 on the downstream side of the coolant passages 50a, 50b, and 50c, respectively. The thermometers 55, 56, and 57 can measure the temperature of the coolant that has flowed from the fuel cell stack 10 to the coolant passages 50a, 50b, and 50c, respectively. The temperatures indicated by the thermometers 55, 56, and 57 can be considered as the temperatures of the A, B, and C region portions of the membrane electrode assembly 12 in each unit fuel cell 11, respectively.

  The measured values of the pressure gauges 36, 40, 42, 46, the dew point meters 38, 44, and the thermometers 55, 56, 57 are supplied to an ECU (Electronic Control Unit) 58. The ECU 58 can detect the environment related to the pressure and temperature inside the unit fuel cell 11 (in other words, around the membrane electrode assembly 12) based on the outputs of these instruments. The ECU 58 is connected to the adjustment valve 28, the compressor 20, the pump 52, and the heat exchangers 53 and 54 described above, and the opening degree and output of each component can be changed.

(Fuel cell in-plane condition estimation routine)
In the present embodiment, the ECU 58 stores an estimation routine that can estimate the internal state of the unit fuel cell 11. According to this estimation routine, the power generation state and power generation environment inside the unit fuel cell 11 can be accurately predicted based on the output of each meter.

  In the first embodiment, this estimation routine is realized by using the estimation method described in Japanese Patent Application No. 2007-138333. According to the estimation method of Japanese Patent Application No. 2007-138333, the environment (gas humidity, pressure, concentration, etc.) of the gas channel inlet of the fuel cell (membrane electrode assembly) and the temperature of the membrane electrode assembly are specified. If it is possible, the power generation environment and the power generation state can be specified over the entire area within the surface of the membrane electrode assembly.

  Also in the system of the first embodiment, the environment at the entrance of the gas flow path can be specified using the measured values of the various instruments described above, as in Japanese Patent Application No. 2007-138333. Moreover, according to the measured value which the thermometers 55, 56, and 57 show, the temperature of the membrane electrode assembly 12 can be grasped over the whole area in the surface. As described above, according to the system of the first embodiment, all the information necessary for the estimation method described in Japanese Patent Application No. 2007-138333 can be acquired. The in-plane state of the fuel cell can be estimated.

  FIG. 4 is a diagram showing the estimation result of the humidity distribution in the unit fuel cell 11 obtained by the estimation routine. In FIG. 4, the distribution of the estimated value of the humidity of the gas flowing through the anode and the distribution of the estimated value of the humidity of the gas flowing through the cathode along the gas flow direction are respectively illustrated. Regions divided by A, B, and C in FIG. 4 correspond to regions A, B, and C of the unit fuel cell 11, respectively. In the following description, the humidity distribution estimated by the estimation routine of the ECU 58 is also referred to as “estimated humidity distribution”.

  In addition, the content of the estimation method of Japanese Patent Application No. 2007-138333 is described at the end of this specification.

[Water movement amount adjustment function of system of Embodiment 1]
Hereinafter, the water movement amount adjustment function of the system according to the first embodiment will be described with reference to FIGS. First, the flow of water and the wet environment inside the unit fuel cell 11 will be described with reference to FIG. Then, the water movement amount adjustment function in the system of this embodiment is demonstrated.

  In FIG. 2, the arrows described inside the membrane electrode assembly 12 indicate the outline of the movement of water inside the unit fuel cell 11. During power generation by the unit fuel cell 11, water is generated in the cathode electrode catalyst layer 12c. Since the gas in the cathode gas flow path 14 flows while containing this generated water, the humidity in the cathode gas flow path 14 becomes higher toward the downstream side. As a result, the portion on the outlet side of the cathode gas flow path 14 is particularly humid.

  Therefore, the humidity difference between the cathode and the anode becomes large at the outlet side portion of the cathode gas flow path 14, and the anode gas flow path 13 is connected from the outlet side of the cathode gas flow path 14 through the membrane electrode assembly 12. Water will move to the entrance side. In the following description, for the sake of convenience, this movement of water is indicated by an arrow f2 in FIG. 2 and the movement amount of water along the arrow f2 is referred to as a water movement amount f2. In FIG. 2, the arrow pointing to the right side of the drawing shown in the electrolyte membrane 12a expresses the movement of moisture carried by the gas for convenience.

  The water that has moved to the inlet side of the gas flow path 13 is contained in the hydrogen gas flowing into the gas flow path 13 (in other words, humidifying the hydrogen gas), and is moved downstream in the gas flow path 13. It is conveyed toward. Moisture in the hydrogen gas contributes to humidification of the membrane electrode assembly 12 from the anode side in the process of flowing in the gas flow path 13. In FIG. 2, the arrow pointing to the left side of the drawing in the electrolyte membrane 12a represents the movement of moisture transported by hydrogen gas.

  On the other hand, the same can be said for the outlet side of the anode gas channel 13 and the inlet side of the cathode gas channel 14. That is, the air at the inlet of the cathode gas channel 14 is relatively dry, whereas the outlet of the anode gas channel 13 is in a high humidity state. Accordingly, a humidity difference between the cathode and the anode is generated even at this position, and water moves from the outlet side of the anode gas flow path 13 to the inlet side of the cathode gas flow path 14 via the membrane electrode assembly 12. In the following description, for the sake of convenience, this movement of water is indicated by an arrow f1 in FIG. 2, and the movement amount of water along the arrow f1 is referred to as a water movement amount f1.

  As described above, in the unit fuel cell 11 of the present embodiment, water as indicated by the arrows f1 and f2 between the anode gas channel 13 and the cathode gas channel 14 is obtained by using the counterflow channel. Urged to move. Thereby, the flow of water that circulates inside the unit fuel cell 11 can be created.

  Next, a method for adjusting the water movement amounts f1 and f2 in the present embodiment will be described. Factors that determine the amount of water movement f1 and f2 include whether the humidity around the membrane electrode assembly 12 is generally high or low, in addition to the magnitude of the humidity difference between the anode and the cathode. This is because the electrolyte, which is a material forming the membrane electrode assembly, has the property that the water permeation characteristics change according to the surrounding humidity.

  The water permeation characteristic of the electrolyte changes so that the higher the ambient humidity is, the easier it is to permeate water, and conversely, the lower the ambient humidity is, the more difficult it is to permeate water. Therefore, in the first embodiment, the water movement amounts f1 and f2 are adjusted as follows using this characteristic.

  As described in the description of the system configuration, in the system according to the first embodiment, the unit fuel cell 11 includes three coolant passages (coolant passages 15a, 15b, and 15c). Then, by controlling the heat exchangers 53 and 54 and the pump 52, the coolants in these three coolant passages can be adjusted to desired temperatures, respectively.

  In order to increase the water movement amount f1, the heat exchanger 53 is operated to lower the temperature of the coolant flowing through the coolant passage 50a. As a result, the temperature of the coolant flowing through the coolant passage 15a of each unit fuel cell 11 decreases, and the region A of the unit fuel cell 11, that is, the outlet side of the anode gas channel 13 and the inlet of the cathode gas channel 14 The temperature of the region facing the side decreases.

  When the temperature of the coolant flowing on the region A is lowered, the relative humidity of the gas on the outlet side of the anode gas channel 13 and the inlet side of the cathode gas channel 14 increases accordingly. If the humidity around the region A of the membrane electrode assembly 12 increases, the water permeation characteristics of the portion change and the water is more easily transmitted. As a result, the amount of water moving from the outlet side of the anode gas channel 13 to the inlet side of the cathode gas channel 14 (that is, the water moving amount f1) can be increased.

  Similarly, the water movement amount f2 can be adjusted by operating the heat exchanger 54 to change the temperature of the coolant on the region C. If the temperature of the coolant flowing through the coolant passage 50a is increased by operating the heat exchanger 53, the water transfer amount f1 can be reduced contrary to the increase in the water transfer amount. The water movement amount f2 can be similarly reduced.

  As described above, according to the first embodiment, by adjusting the temperature of the coolant in the coolant passages 15a and 15c, the inlet side portion and the outlet side portion of the gas flow passages 13 and 14 are opposed to each other. The humidity of the gas in the areas (A and C areas) to be changed can be changed to a desired value. As a result, the water transfer amounts f1 and f2 can be adjusted by changing the water permeation characteristics of the membrane electrode assembly in the A and C regions as necessary.

  In the present embodiment, temperature control is locally performed only on the A and C region side portions of the unit fuel cell 11 related to the water movement amounts f1 and f2. According to such a technique, the following effects can also be obtained.

  One factor affecting the power generation performance of a fuel cell is the temperature inside the fuel cell during power generation. This is because when the temperature in the fuel cell decreases, the activity of the catalyst in the electrode catalyst layer decreases. In this regard, according to the first embodiment, the temperature adjustment of the A and C regions can be performed independently of the central B region. Therefore, it is possible to perform power generation in a normal temperature state in the B region and to generate power in a low temperature state or a high temperature state in the A and C regions in order to adjust the water movement amounts f1 and f2. As a result, the water movement amounts f1 and f2 can be adjusted while maintaining the normal power generation performance of the unit fuel cell 11 as much as possible.

[Operation of System of First Embodiment]
The operation of the system according to the first embodiment will be described below. The operation of the system according to the present embodiment is characterized in that the lack of water movement amount is determined and the above-described water movement amount adjustment function is utilized according to the determination result.

  In Embodiment 1, paying attention to the humidity on the inlet side of the anode gas flow path 13 and the humidity on the inlet side of the cathode gas flow path 14, it is determined whether the amount of water movement is insufficient. The system of Embodiment 1 can estimate the humidity distribution of each gas flow path in the unit fuel cell 11 as shown in FIG. 4 by the estimation routine stored in the ECU 58. By referring to this humidity distribution, the humidity value near the inlet or outlet of the anode gas channel 13 and the estimated value of humidity near the inlet or outlet of the cathode gas channel 14 can be obtained. In the first embodiment, these estimated values are used.

  In the present embodiment, the allowable range of the humidity on the inlet side of the anode gas flow path 13 is determined in advance using experiments or simulations. This permissible range can be, for example, a humidity range on the inlet side of the anode gas passage 13 such that the unit fuel cell 11 can exhibit good power generation characteristics. Similarly, the allowable humidity range on the inlet side of the cathode gas channel 14 is also determined. The humidity range can be determined from various points of view. For example, the humidity range in which the membrane / electrode assembly 12 can be determined to be in a good wet state and the electrical characteristics of the membrane / electrode assembly 12 are acceptable. It is good also as a humidity range etc. which can be judged that it exists in a range.

  In other words, “the situation where the humidity on the inlet side of the anode gas flow path 13 is lower than the lower limit of the allowable humidity range (hereinafter also referred to simply as the lower limit value)” means that the humidity on the inlet side of the anode gas flow path 13 is It can be said that “the amount of water movement f2 is not sufficient to maintain the desired wet state”. If the water is sufficiently supplied along the arrow f2 (that is, if the water movement amount f2 is sufficient), it is possible to prevent the humidity on the inlet side of the anode gas flow path 13 from becoming excessively low. is there. Therefore, in the present embodiment, when the humidity on the inlet side of the anode gas flow path 13 falls below the lower limit value, the water movement amount f2 is considered to be insufficient. Similarly, if the estimated value of the humidity on the inlet side of the cathode gas channel 14 is below the lower limit value, the water movement amount f1 is considered to be insufficient.

  In the present embodiment, first, in order to detect the above shortage of water movement, the estimated value acquired based on the estimation routine is compared with the lower limit value of the allowable humidity range at any time during power generation of the fuel cell stack 10. . When the estimated value of the humidity on the inlet side of the anode gas flow path 13 falls below the lower limit value, the cooling capacity of the heat exchanger 53 is increased. Similarly, when the estimated value of the humidity on the inlet side of the cathode gas channel 14 is below the lower limit value, the cooling capacity of the heat exchanger 54 is increased. As a result, when necessary, the temperature of the coolant passages 15a and 15c can be quickly reduced, and the water movement amounts f1 and f2 can be increased.

  As described above, according to the first embodiment, when it is predicted that the water movement amounts f1 and f2 are insufficient, the water movement amounts f1 and f2 are set to suitable amounts by quickly dealing with this. Can be adjusted. As a result, power generation can be performed while keeping the inside of the unit fuel cell 11 in a favorable wet environment.

  When reducing the coolant temperature of the coolant passages 15a and 15c to increase the amount of water movement, if the coolant temperature is lowered to such an extent that the moisture of the gas in each gas channel is condensed, The C region portion can be moistened with the water generated thereby.

[Specific Processing Performed by ECU in System of Embodiment 1]
Hereinafter, specific processing performed by the system according to the first embodiment will be described with reference to FIGS. FIG. 5 is a flowchart of a routine executed by ECU 58 in the first embodiment. This routine is executed during the power generation of the system according to the first embodiment.

  FIG. 6 is a map that defines the relationship between the output current value Ia and the coolant target temperature. Each map in FIGS. 6A and 6B is determined so that the values of the target temperatures T1 and T2 increase as the output current value Ia of the fuel cell stack 10 increases. However, in this embodiment, the temperature difference between the coolant temperatures ta and tc and the coolant temperature tb is set within a predetermined range (10 ° C. in this embodiment).

  In the present embodiment, the difference between the lowest target temperature T1_min and the highest target temperature T1_max and the difference between the lowest target temperature T2_min and the highest target temperature T2_max in the map of FIG. T1_max and T2_max are made to coincide with the coolant temperature during normal power generation of the fuel cell stack 10 (that is, the value of the coolant temperature tb during normal power generation). These maps are created in advance and stored in the ECU 58.

  In the routine shown in FIG. 5, first, estimation of the humidity distribution by the estimation routine is executed (step S100). In this step, the ECU 58 executes an estimation routine stored therein using output values of various instruments of the system. Thereby, an estimated humidity distribution as shown in FIG. 4 is obtained.

  In this embodiment, for simplification of description, one unit fuel cell 11 is selected as a representative from the fuel cell stack 10, and the process proceeds using the estimated humidity distribution for the representative unit fuel cell 11. To do. However, the method of obtaining the estimated humidity distribution used for the operation of the present embodiment is not limited to this. For example, the estimated humidity distribution may be calculated for all the unit fuel cells 11 in the fuel cell stack 10 and the average of these estimated humidity distributions may be used.

  Subsequently, the process of step S102 is executed. In step S102, the representative humidity hai of the inlet side portion and the representative value hao of the outlet side portion of the anode gas flow path 13 are calculated using the estimated humidity distribution obtained in step S100. Similarly, using the estimated humidity distribution, the representative value hci of the humidity at the inlet side and the representative value hco of the humidity at the outlet side in the cathode gas flow path 14 are calculated (hereinafter simply referred to as “humidity hai, Also called “hao, hci, hco”).

  In the present embodiment, the humidity hai and the humidity hao are the humidity values at the center positions of the A and C regions in the estimated humidity distribution of the anode, as shown in FIG. Similarly, the humidity hci and the humidity hco are set to the humidity values at the center positions of the A and C regions in the estimated humidity distribution of the cathode. The humidity hai, hao, hci, and hco may be determined by other methods. For example, the average values of the estimated humidity in the A and C regions of the anode and the cathode are obtained using the portions in the A and C regions of the estimated humidity distribution. Then, the average value of the estimated humidity in the A region of the anode may be used as the humidity hai, and the average value of the estimated humidity in the C region of the anode may be used as the humidity hao. Similarly, the average values of the estimated humidity in the A and C regions of the cathode can also be used for the humidity hci and hco.

Subsequently, the humidity environment at the inlet side of the cathode gas channel 14 is evaluated using the humidity calculated in step S102 (step S104). Specifically, first, in step S104, it is determined whether or not the humidity hci is below the lower limit value H1. That is, it is determined whether or not the following expression (1) is established.
hci <H1 (1)
As described above, the lower limit value H1 is determined in advance by experiments or the like. This determination makes it possible to determine whether or not the inlet side of the cathode gas flow path 14 is currently dried and it is necessary to increase the amount of water movement.

  In step S104, it is also determined whether or not the value obtained by subtracting the humidity hci from the humidity hao is greater than a predetermined humidity difference ΔH1. As described above, the factors that determine the amount of water movement include the difference in humidity between the two surfaces of the membrane electrode assembly (or electrolyte membrane) (that is, the difference between the humidity on the anode side and the humidity on the cathode side). Large and small). If the humidity difference is too small, there is a possibility that even if the humidity around the membrane electrode assembly 12 is increased to improve the water permeation characteristics, the effect of increasing the amount of water movement cannot be expected.

Therefore, in the present embodiment, the ECU 58 is caused to execute the following processing in order to perform processing for increasing the amount of water movement after reliably grasping that the water movement can be promoted. First, a value indicating how much the humidity on the outlet side of the anode gas flow path 13 is higher than the humidity on the inlet side of the cathode gas flow path 14 is obtained by subtracting the humidity hci from the humidity hao. Then, the value obtained by subtracting hci from hao is compared with a predetermined reference humidity difference ΔH1. That is, it is determined whether or not the following expression (2) is established.
hao−hci> ΔH1 (2)

  In this embodiment, when the two determination conditions in step S104, that is, both the expressions (1) and (2) are satisfied, the process for increasing the amount of water movement (next step S106) is executed. Is done. As a result, in this embodiment, it is necessary to increase the water movement amount f1, and after confirming that it is possible to obtain a desired water movement promotion effect, the increase in the water movement amount f1 is increased. You can move on to processing.

  The humidity difference ΔH1 can be determined in advance by an experiment or the like. In order to reliably promote water movement between the two poles, at least the humidity of the pole that is desired to be the source of water is required to be higher than the humidity of the pole that is desired to be the destination of water. For this reason, in order to increase the water movement amount f1 with certainty, it is necessary to set ΔH1 to a value at least larger than zero in the above-described determination formula.

  If at least one of the determination conditions (hci <H1, hao−hci> ΔH1) in step S104 is not satisfied, it is determined that the process of increasing the water movement amount f1 should not be executed at the present time. Then, it returns to step S100.

  When the determination condition in step S104 is established, a process for reducing the temperature of the coolant flowing into the coolant passage 15a is executed (step S106). Specifically, the ECU 58 operates the heat exchanger 53 to adjust the temperature of the coolant in the coolant passage 50a so that the coolant temperature ta measured by the thermometer 55 matches the target temperature T1. Thereby, the temperature of the coolant flowing into the coolant passage 15a of each unit fuel cell 11 is lowered, and the amount of water movement f1 in each unit fuel cell 11 can be increased.

  As described above, in the present embodiment, the ECU 58 stores a map for acquiring the target temperature T1 shown in FIG. The map in FIG. 6A is determined so that the target temperature T1 increases as the output current value Ia of the fuel cell stack 10 increases. When the output current value Ia is large, the amount of water in the unit fuel cell 11 is expected to be relatively large because the amount of water produced due to the power generation reaction increases. In the present embodiment, in consideration of this, the target temperature of the coolant is increased when the output current value Ia is relatively large, and the target temperature of the coolant is increased when the output current value Ia is relatively small. The setting is low.

  According to the flowchart of FIG. 5, steps S108 and S110 are also executed in parallel with the processing on the side of steps S104 and S106. In steps S108 and S110, processing similar to that in steps S104 and S106 is performed using humidity hai and hco as described below.

First, in step S108, the humidity environment on the inlet side of the anode gas flow path 13 is evaluated using the humidity hai and hco. Specifically, it is determined whether or not the following expression (3) is established, and it is determined whether or not the humidity hai is below the lower limit value H2. The lower limit value H2 is determined in advance by experiments or the like, similarly to the lower limit value H1 described above. In step S108, it is also determined whether or not the following expression (4) is established.
hai <H2 (3)
hco-hai> ΔH2 (4)

  Based on these determinations, as in step S104 described above, the water movement amount f2 needs to be increased, and it is possible to obtain the desired water movement promotion effect, and then the water movement The process can be shifted to the process of increasing the amount f2 (step S110). If at least one of the determination conditions (hai <H2, hco-hai> ΔH2) in step S108 is not satisfied, it is determined that the process of increasing the water movement amount f2 should not be executed at this time, and step S100 Return to.

  When the determination condition in step S108 is satisfied, a process for reducing the temperature of the coolant flowing into the coolant passage 15c is executed (step S110). In step S110, specifically, as in the process of step S106, the ECU 58 operates the heat exchanger 54 so that the coolant temperature tc, which is the measurement value of the thermometer 57, matches the target temperature T2. As a result, the temperature of the coolant flowing into the coolant passage 15c of each unit fuel cell 11 decreases, and the amount of water movement f2 of each unit fuel cell 11 can be increased.

  The ECU 58 also stores a map for acquiring the target temperature T2 as shown in FIG. The map in FIG. 6B is also determined so that the target temperature T2 increases as the output current value Ia of the fuel cell stack 10 increases for the same reason as the map in FIG.

  After the process of step S106 or step S110 is executed, the current routine ends. Thereafter, in the present embodiment, the system operation is continued while the coolant temperatures ta and tc are set to T1 and T2, respectively.

  In the first embodiment, after completion of the routine, the routine of FIG. 5 is stopped and the following processing is performed. First, the estimation routine used in step S100 is repeatedly executed to continuously update the estimated humidity distribution in the unit fuel cell 11. Then, the values of the humidity hai and hci are monitored, and when those values are sufficiently high (for example, hci is H1 or higher and hai is H2 or higher), the coolant temperatures ta and tc are changed to the coolant temperatures. Return to the same temperature as tb. Thereafter, the execution of the routine of FIG. 5 is resumed, and the determination of insufficient water movement is resumed.

  As described above, according to the specific processing of this embodiment, when it is considered that the water movement amounts f1 and f2 are insufficient, the inlet side portion and the outlet side portion of the gas flow path are opposed to each other. The area (A, C area) to be performed can be lowered. As a result, the amount of water movement can be quickly increased when necessary, and the amount of water movement f1, f2 between the anode and the cathode can be brought close to a suitable value.

  In particular, according to the present embodiment, the estimated value (hai, hci) of the humidity at the inlet side portion of each gas flow path is compared with predetermined determination values (H1, H2). The inlet side portion of each gas flow path is a portion that is relatively easily dried even in the unit fuel cell 11. Therefore, according to the present embodiment, when the moisture in the unit fuel cell 11 is insufficient and an increase in the amount of water movement becomes an urgent matter, it is possible to quickly cope with this. Further, according to the present embodiment, the humidity difference between the anode and the cathode for each of the A and C regions is compared with predetermined determination values (ΔH1, ΔH2). Thereby, it is possible to perform processing for increasing the amount of water movement after reliably grasping that the water movement can be promoted (a sufficient effect can be obtained).

  Note that the control of the system after the end of the routine of FIG. 5 is not limited to the aspect of the first embodiment. For example, the coolant temperatures ta and tc may be returned to their original temperatures (for example, the same temperature as the coolant temperature tb) in anticipation of the time when the wet environment in the unit fuel cell 11 settles to an ideal state. The time when the wet environment settles may be determined from various viewpoints such as the elapsed time from the routine end time.

  In the first embodiment described above, the membrane electrode assembly 12 corresponds to the “membrane electrode assembly” in the first invention, and the unit fuel cell 11 corresponds to the “fuel cell” in the first invention. ing. In this embodiment, since the gas flow path of the unit fuel cell 11 has a counter flow flow path structure, the anode gas flow path 13 and the cathode gas flow path 14 are both “first” in the first invention. It can correspond to “one gas flow path” and “second gas flow path”.

  That is, in the first embodiment, the cathode gas passage 14 corresponds to the “first gas passage” in the first invention, and the anode gas passage 13 is the “second gas flow” in the first invention. When it is considered that it corresponds to a “channel”, the coolant passage 15a provided in the A region where the inlet side portion of the cathode gas channel 14 and the outlet side portion of the anode gas channel 13 face each other is the first invention. Corresponds to the “first refrigerant passage” in FIG. In the first embodiment, the anode gas passage 13 corresponds to the “first gas passage” in the first invention, and the cathode gas passage 14 is the “second gas flow” in the first invention. When it is considered that it corresponds to a “channel”, the coolant passage 15c provided in the C region where the inlet side portion of the anode gas passage 13 and the outlet side portion of the cathode gas passage 14 face each other is the first invention. Corresponds to the “first refrigerant passage” in FIG.

  In the first embodiment, the coolant passage 15b corresponds to the “second refrigerant passage” in the first invention. In the first embodiment, the coolant passage 50, the radiator 51, and the pump 52 correspond to the “refrigerant supply means” in the first invention. The heat exchangers 53 and 54 correspond to the “adjustment mechanism” in the first invention.

  Further, in the first embodiment, the ECU 58 executes the process of step S104 or / and S108 in the routine of FIG. 5 so that the “insufficient determination means” in the second aspect of the invention is step S106 or / and S110. By executing the process, the “cooling control means” in the second aspect of the present invention is realized.

  In the first embodiment, the ECU 58 executes steps S100 and S102 in the routine of FIG. 5, thereby realizing the “inlet-side humidity acquisition means” in the third aspect of the invention. In the first embodiment, the humidity hci or hai corresponds to the “first gas flow path inlet humidity” in the third invention, and the lower limit value H1 or H2 is the “lower limit value” in the third invention. It corresponds.

  In the first embodiment, the ECU 58 executes steps S100 and S102 in the routine of FIG. 5, thereby realizing the “exit-side humidity acquisition means” in the sixth aspect of the invention. In the first embodiment, the humidity hco or hao corresponds to the “second gas flow path inlet humidity” in the sixth aspect of the invention. Further, the ECU 58 executes step S104 and / or S108 in the routine of FIG. 5, thereby realizing the “environment determining means” in the sixth aspect of the invention. In the first embodiment, the humidity difference ΔH1 or ΔH2 corresponds to the “determination value” in the sixth aspect of the invention.

[Modification of Embodiment 1]
(First modification)
In the first embodiment, heat exchangers 53 and 54 are provided in the coolant passages 50a and 50c, respectively, and the temperatures in the surface of the unit fuel cell 11 are partially varied by appropriately operating these. However, the present invention is not limited to this, and the in-plane temperature of the unit fuel cell 11 may be partially varied according to other modes.

  FIG. 7 shows a modification of the first embodiment. The system shown in FIG. 7 is omitted because the system configuration other than the configuration of the cooling system is the same as that of the system shown in FIG. The system in FIG. 7 includes valves 253 and 254 instead of the heat exchangers 53 and 54 in the system in FIG. According to the valves 253 and 254, the flow rate of the coolant in the coolant passages 50a and 50c can be adjusted.

  If the flow rate of the coolant in the coolant channels 50a and 50c is large, the flow rate of the coolant in the coolant channels 15a and 15c of the individual unit fuel cells 11 is increased accordingly, and as a result, the membrane electrode assembly 12 is increased. The temperature of the A region and the C region of the film decreases. In this way, the coolant temperature in the unit fuel cell 11 may be partially different.

  In the modification of the first embodiment described above, the valves 253 and 254 correspond to the “adjustment mechanism” of the first invention. Note that, according to the first modification of FIG. 7, when the coolant flow rate in the coolant passages 50a and 50c changes according to the adjustment of the valves 253 and 254, the coolant flow rate in the coolant passage 50b also has an effect. receive. For example, in the case of the first modification, when the cooling liquid flow rate in the cooling liquid passages 50a and 50c is increased and the cooling temperature of the A and C regions in the individual unit fuel cells 11 is decreased, according to this, It is also anticipated that the coolant flow rate in the coolant passage 50b decreases and the temperature of the B region in each unit fuel cell 11 rises.

  In this case, for example, the flow rate of the pump 52 can be increased and the cooling temperature of the radiator 51 can be decreased so as to cancel out such a temperature increase in the region B. In this way, the temperatures of the A and C regions can be lowered while maintaining the temperature of the B region in the state during normal power generation for each unit fuel cell 11. In this way, although the coolant flow rate changes in the coolant passages 50a, 50b, and 50c are affected by each other, the coolant temperature in these coolant passages is changed independently of each other also by the embodiment of the modified example of FIG. be able to.

  In the first embodiment, the coolant passage 50 is branched into the coolant passages 50a, 50b, and 50c, so that the coolant is supplied to each coolant passage in the unit fuel cell 11 with one common cooling system. The temperature can be adjusted independently. However, three cooling systems independent of each other may be configured, and the respective cooling systems may be connected to the fuel cell stack 10 instead of the coolant passages 50a, 50b, and 50c.

  In the first embodiment, the temperature of the A and C regions of the unit fuel cell 11 can be partially reduced by configuring the independent coolant passages in a parallel connection relationship. However, the present invention is not limited to this. For example, the temperature adjustment of the A and C regions of the unit fuel cell 11 is performed by connecting the coolant passages in series via a heat exchanger as described in Patent Document 2 (Japanese Patent Laid-Open No. 2001-43871) cited as a prior art document. It may be realized by using a system configuration that is connected to each other.

(Second modification)
In the first embodiment, the humidity distribution in each of the anode and the cathode in the unit fuel cell 11 is estimated, and using this estimated value, it is determined whether or not the amount of water movement is insufficient. However, the present invention is not limited to this. A humidity sensor may be attached to each of the inlet side portion and the outlet side portion of each gas flow path to measure the humidity at each position.

  When direct measurement using a humidity sensor is compared with a method for estimating the humidity inside the unit fuel cell 11 by estimation, the method using estimation has the following advantages.

  In order to accurately adjust the amount of water movement, it is preferable that the humidity at the center position of the coolant passages 15a and 15c (the humidity of the gas flow path at the center of the A and C regions) inside the unit fuel cell 11 can be grasped. Therefore, when the humidity is directly measured using the sensor, it is preferable to perform the measurement by arranging the sensor inside the gas flow path of the unit fuel cell 11. Specifically, it is preferable that the humidity at a position slightly behind the end (inlet or outlet) of the gas flow path (a position corresponding to the center of the A region or the C region) can be directly measured by a sensor. However, it may be difficult or complicated to directly measure such a place with a sensor.

  In this regard, according to the first embodiment, as shown in the system configuration diagram (FIG. 1), sensors are provided in the oxidizing gas supply passage 17, the oxidizing gas discharge passage 16, the fuel gas supply passage 24, and the fuel gas discharge passage 26. It arrange | positions and grasps | ascertains the environment inside the gas flow path of the unit fuel cell 11 by estimation. Therefore, it is possible to accurately adjust the water movement amounts f1 and f2 while avoiding the complexity described above.

  In addition, instead of estimating the power generation environment over the entire area of the unit fuel cell 11 as in the first embodiment, an estimation method is used to locally estimate the humidity at the inlet and outlet of the gas flow path. Also good.

  The unit fuel cell 11 of Embodiment 1 has a structure of a counter flow channel, that is, a structure in which the flow of two gas channels sandwiching a membrane electrode assembly is directed in opposite directions. However, the present invention provides an outlet side portion of one gas flow channel and an inlet side portion of the other gas flow channel sandwiching the membrane electrode assembly, even if the flows of the two gas flow channels are not completely opposite to each other. It is possible to apply to any fuel cell that is facing each other.

  For example, the present invention can be applied to a fuel cell in which only a cathode gas channel outlet side portion and an anode gas channel inlet side portion face each other through a membrane electrode assembly. In this case, the region in the fuel cell surface is divided into a region where the cathode gas flow channel outlet side portion and the anode gas flow channel inlet side portion face each other, and other regions.

  Then, it is only necessary to provide a coolant passage individually in each of the divided regions so that the temperature or flow rate of the coolant can be adjusted independently between the coolant passages.

  The gas discharged from the oxidizing gas discharge passage 16 contains moisture. Although not used in the system of the first embodiment, a humidifier may be added to the system to humidify the air on the oxidizing gas supply passage 17 side using moisture contained in the oxidizing gas discharge passage 16.

Embodiment 2. FIG.
The system configuration of the second embodiment is the same as the system of the first embodiment shown in FIG. Therefore, the description of the system configuration of the second embodiment is omitted.

[Operation of System of Embodiment 2]
In the first embodiment, it is determined whether the amount of water movement is insufficient based on the humidity on the inlet side of the gas flow path. On the other hand, in the second embodiment, whether or not the water movement amount is insufficient is determined by paying attention to whether the water movement amount itself (that is, the absolute value of the water movement amount) is large or small.

  Specifically, in the second embodiment, an estimated value of the amount of water movement is obtained using humidity and other various physical quantities, and it is determined whether or not the amount of water movement is insufficient based on the magnitude of this estimated value. . Thereby, the shortage of the amount of water movement can be detected more directly, and the amount of water movement can be adjusted and managed with higher accuracy.

  In the second embodiment, in addition to the determination of the shortage of the water movement amount, it is also determined whether or not the water movement amount is excessive. Under the situation where the amount of water movement is estimated to be excessive, the membrane electrode assembly 12 may have an excessive water content, which may cause various problems (for example, reduction in power generation performance, flooding, etc.). In the second embodiment, considering this point, it is also determined whether the amount of water movement is excessive, and the wet environment in the unit fuel cell 11 is maintained in a more appropriate state.

[Specific processing executed by ECU in system of embodiment 2]
Hereinafter, specific processing performed by the system according to the second embodiment will be described with reference to FIGS. FIG. 8 is a flowchart of a routine executed by the ECU 58 in the second embodiment. This routine is executed during power generation of the system according to the second embodiment.

  FIG. 9 is a map that defines the water permeability coefficient of the membrane electrode assembly 12 in relation to the environment (humidity average value and temperature) around the membrane electrode assembly 12. Specifically, FIG. 9A shows the water permeability coefficient K1 on the A region side of the membrane electrode assembly 12 as an average value of the humidity on the anode side and the humidity on the cathode side (here, (hao + hci) / 2, That is, it is a two-dimensional map defined by the relationship between the humidity hao and the sum of hci) and the ambient temperature on the A region side (in this embodiment, the coolant temperature ta).

  FIG. 9B shows the water permeability coefficient K2 on the C region side of the membrane electrode assembly 12 as well as the average value of humidity (here, (hai + hco) / 2, that is, the average of the sum of the humidity hai and hco). , A two-dimensional map defined by the relationship with the ambient temperature on the A region side (in this embodiment, the coolant temperature tc). Using these maps, the water permeability coefficients K1 and K2 in the A and C regions of the membrane electrode assembly 12 can be specified in accordance with the temperatures ta and tc and the humidity hao, hci, hai and hco.

  The map of FIG. 9 is created in advance based on, for example, experiments, simulations, theoretical equations, or the like, and stored in the ECU 58.

  10A and 10B show the target water movement amounts F1 and F2 used as the target values of the water movement amounts f1 and f2 when adjusting the water movement amount, and the output current values of the fuel cell stack 10. It is a two-dimensional map determined according to Ia and operating temperature (in this embodiment, it is set as the coolant temperature tb).

  When the output current value Ia is large, the amount of water in the unit fuel cell 11 is expected to be relatively large because the amount of water produced due to the power generation reaction increases. In the second embodiment, in consideration of this, the target water movement amounts F1 and F2 are specified to be smaller as the output current value Ia is larger. Further, when the operating temperature of the fuel cell stack 10 is high, it can be considered that the environment inside the fuel cell stack 10 (the environment inside each unit fuel cell 11) is relatively easy to dry. In the present embodiment, in consideration of this, the numerical value of the map is defined so that the target water movement amounts F1 and F2 increase as the coolant temperature tb increases.

  In the routine of FIG. 8, first, similarly to the routine of FIG. 5 of the first embodiment, the process of step S100 is executed, and the humidity distribution is estimated by the state estimation model.

  Subsequently, for each of the cathode gas channel 14 and the anode gas channel 13, a process for obtaining the humidity and pressure of the inlet and outlet of the gas channel is executed (step S302). Specifically, in this step, first, the humidity hao, hci, hai, and hco are calculated by the same processing as in step S102 of the first embodiment.

  Further, by proportional calculation based on the measured values of the pressure gauges 42, 46, 36, 40, the inlet side pressure pai and the outlet side pressure pao of the anode gas flow path 13, the inlet side pressure pci of the cathode gas flow path 14 and the outlet side The pressure pco is calculated respectively. Note that these pressure values can be obtained by proportional calculation based on, for example, pressure gauge measurement values at the inlet and outlet of the gas flow path of the unit fuel cell 11. In the cross-sectional view of the unit fuel cell 11 in FIG. 2, pai, pao, pci, and pco are shown so that the corresponding positions can be seen.

Next, in the second embodiment, a process of calculating the estimated value f1_a of the water movement amount f1 and the estimated value f2_a of the water movement amount f2 is executed (step S304). Specifically, first, the ECU 58 acquires the estimated values of various physical quantities obtained in step S302 and the values of K1 and K2 corresponding to the coolant temperatures ta and tc from the map of FIG. Subsequently, the estimated water movement amount f1_a and the estimated water movement amount f2_a are calculated according to the following equations (5) and (6).
f1_a = K1 × (pao × hao−pci × hci) (5)
f2_a = K2 × (pai × hai−pco × hco) (6)

  In the above formulas (5) and (6), the formulas shown in the right parenthesis respectively correspond to formulas for calculating the water vapor partial pressure difference between the anode and the cathode across the membrane electrode assembly 12. Thus, in Embodiment 2, the amount of water movement is estimated based on the product of a water permeability coefficient and a water vapor partial pressure difference.

  Subsequently, in the routine of FIG. 8, processing relating to the water movement amount f1 (steps S306, S308, S310, S312) and processing relating to the water movement amount f2 (steps S314, S316, S318, S320) are executed. Each will be described below.

(Processing on the amount of water movement f1)
In step S306, it is determined whether or not the estimated water movement amount f1_a calculated in step S304 is larger than a predetermined upper limit value F1 + α. Here, first, the ECU 58 refers to the map of FIG. 10A to acquire the target water movement amount F1 according to the current output current value Ia and the coolant temperature tb. A value obtained by adding the predetermined value α to the target water movement amount F1 is set as an upper limit value F1 + α, and it is determined whether f1_a exceeds the upper limit value F1 + α.

  When the establishment of the condition in step S306 is confirmed, it is determined that the water movement amount f1 is excessive, and a process for increasing the coolant temperature ta is performed (step S308). Here, the ECU 58 operates the heat exchanger 53 so that the coolant temperature ta rises from the current temperature by a predetermined temperature. As a result, the temperature of the coolant flowing into the coolant passage 15a of each unit fuel cell 11 rises, and the humidity on the outlet side of the anode gas passage 13 and the inlet side of the cathode gas passage 14 decreases accordingly. (That is, hao, hci decrease). As a result, the water movement amount f1 of each unit fuel cell 11 can be reduced.

  Note that, during the coolant temperature control in step S308, the coolant temperature ta can be raised, for example, to be about 10 ° C. higher than the current coolant temperature tb. However, it is preferable to provide an upper limit for the temperature of the coolant temperature ta. In the present embodiment, the coolant temperature ta is raised within a range where the temperature difference with respect to the coolant temperature tb at the time of execution of step S308 does not exceed 10 ° C. When the process of step S308 ends, the process proceeds to step S314 to perform a process related to the adjustment of the water movement amount f2.

  When the establishment of the condition in step S306 is not recognized, it is determined whether or not the estimated water movement amount f1_a is smaller than a predetermined lower limit value F1-α (step S310). F1-α, which is the lower limit, is a value obtained by subtracting the predetermined value α from the value of the target water movement amount F1, contrary to step S306.

  When the establishment of the condition of step S310 is recognized, it is determined that the water movement amount f1 is insufficient, and a process of reducing the coolant temperature ta is executed (step S312). Here, contrary to the process of step S308, the ECU 58 operates the heat exchanger 53 so that the coolant temperature ta decreases by a predetermined temperature from the current temperature. Thereby, the water movement amount f1 of each unit fuel cell 11 can be increased.

  In the cooling liquid temperature control in step S312, the cooling liquid temperature ta can be lowered, for example, to be about 10 ° C. lower than the current cooling liquid temperature tb. However, as in step S308, a lower limit is set for the temperature of the coolant temperature ta. In the present embodiment, the coolant temperature ta is decreased within a range where the temperature difference with respect to the coolant temperature tb at the time of execution of step S312 does not exceed 10 ° C. In addition, the map of FIG. 6 of Embodiment 1 can also be diverted. When the process of step S312 is completed, the process proceeds to step S314 to perform a process related to the adjustment of the water movement amount f2.

  If the establishment of the condition in step S306 is not recognized and the establishment of the condition in step S310 is not recognized, the process related to the adjustment of the water movement amount f2 without performing the process related to the adjustment of the water movement amount f1 ( The process proceeds to step S314). Here, when the conditions of steps S306 and S310 are not satisfied, it means that the condition of F1-α ≦ f1_a ≦ F1 + α is satisfied.

  That is, the coolant temperature ta is adjusted so that the estimated value f1_a is within a specific range (F1−α ≦ f1_a ≦ F1 + α) by repeatedly executing a series of steps S306, S308, S310, and S312. Will be. In response to this, the water movement amount f to be estimated is maintained within a specific range.

(Processing on water movement amount f2)
Next, the process of step S314 is performed in order to perform the process regarding adjustment of the water movement amount f2. In this step, the same process as in step S306 is performed on the estimated water movement amount f2_a. First, the ECU 58 acquires the target water movement amount F2 corresponding to the current output current value Ia and the coolant temperature tb from the map of FIG. Subsequently, the upper limit value F2 + β is determined by the sum of the target water movement amount F2 and the predetermined value β, and it is determined whether or not the estimated water movement amount f2_a exceeds the upper limit value F2 + β.

  If the establishment of the condition in step S314 is confirmed, it is determined that the water movement amount f2 is excessive, and a process of increasing the coolant temperature tc is executed (step S316). The process of step S316 can be realized by performing the same process as step S308 described above for the coolant temperature tc. Therefore, the description is omitted. When the process of step S316 is completed, the current routine ends.

  If the establishment of the condition in step S314 is not confirmed, it is determined whether or not the estimated water movement amount f2_a is smaller than a predetermined lower limit value F2-β (step S318). In this step, it is determined whether or not the estimated water movement amount f2_a is below the lower limit value F2-β.

  If the establishment of the condition in step S314 is confirmed, it is determined that the water movement amount f2 is excessive, and a process of increasing the coolant temperature tc is executed (step S316). The process of step S320 can be realized by performing the same process as step S312 described above for the coolant temperature tc. Therefore, the description is omitted. When the process of step S320 is completed, the current routine ends.

  If the establishment of the condition in step S314 is not recognized and the establishment of the condition in step S318 is not recognized, the current routine is terminated without performing the process related to the adjustment of the water movement amount f2. If the conditions of steps S314 and S318 are not satisfied, it means that the condition of F2-β ≦ f2_a ≦ F2 + β is satisfied. Therefore, in the same manner as described in the processing relating to the water movement amount f1, the coolant is repeatedly executed so that the estimated value f2_a falls within a specific range (F2-β ≦ f2_a ≦ F2 + β). The temperature tc will be adjusted. In response to this, the amount of water movement f2 to be estimated is maintained within a specific range.

  As described above, according to the specific processing of the second embodiment, when it is considered that the water movement amounts f1 and f2 are insufficient, the inlet side portion and the outlet side portion of the gas flow channel face each other. The located region (A, C region) can be lowered in temperature. As a result, the amount of water movement can be quickly increased when necessary, and the amount of water movement f1, f2 can be as close to a suitable value as possible.

  In particular, according to the second embodiment, the estimated values f1_a and f2_a are obtained by estimating and calculating the water movement amounts f1 and f2, and the system is controlled according to the magnitudes of the estimated values f1_a and f2_a. As described above, in the second embodiment, the amount of water movement is not the change of the humidity environment in the unit fuel cell 11 (for example, the change of the humidity at the inlet of each gas flow path) but the water movement amount f1, f2 itself. Judgment of lack of. Thereby, adjustment of the amount of water movement can be accurately performed according to a change in the absolute amount of the amount of water movement f1, f2.

  According to the first embodiment, the water movement amounts f1 and f2 considered to be difficult to actually measure and measure are positioned so that the inlet side portion and the outlet side portion of each gas flow channel face each other. Based on information (specifically, humidity, temperature, pressure) regarding the environment in the areas (A and C areas), it can be grasped by estimation.

  In the second embodiment, it is also determined whether or not the water movement amounts f1 and f2 are excessive, and the water movement amounts f1 and f2 are also suppressed according to the determination result. Thereby, when it is considered that the water movement amounts f1 and f2 are excessive, the water movement amounts f1 and f2 can be quickly reduced.

  In the second embodiment described above, the “insufficient determination means” in the second aspect of the present invention is realized by the ECU 58 executing the processing of step S310 or / and S318 in the routine of FIG. . Further, the “cooling control means” according to the second aspect of the present invention is implemented by executing the processing of step S308 or / and S312.

  Further, in the second embodiment, the “water movement amount acquisition means” in the fourth aspect of the present invention is realized by the ECU 58 executing the process of step S304 in the routine of FIG. Further, by executing the processing of step S310 or / and S318, the function realized by the “insufficient determination means” in the fourth invention is realized. In the second embodiment, the lower limit value F1-α and the lower limit value F2-β correspond to the “lower limit value” in the fourth invention.

  In the first embodiment, the ECU 58 executes steps S100 and S302 in the routine of FIG. 8, so that the “gas flow path environment obtaining unit” in the fifth aspect executes the process of step S304. Thus, the “estimation calculation means” in the fifth aspect of the invention is realized. In addition, since the ECU 58 stores the above-described equations (5) and (6), the “water movement characteristic storage means” in the fifth aspect of the present invention is realized.

  In the second embodiment described above, the ECU 58 executes the process of step S306 or / and S314 in the routine of FIG. 8 so that the “excess determination means” in the seventh aspect of the invention is step S308 or By executing the process of / and S316, the “temperature increase control means” in the seventh aspect of the present invention is realized.

[Modification of Embodiment 2]
In the second embodiment, the estimated values f1_a and f2_a of the water movement amount are obtained by executing the process of step S304 of the routine shown in FIG. However, the present invention is not limited to this. For example, in the estimation method described in Japanese Patent Application No. 2007-138333, there is a step of calculating the amount of water movement H2O_m through the membrane electrode assembly 12 for each small region. In this embodiment, since an estimation routine based on the estimation method described in Japanese Patent Application No. 2007-138333 is executed, there is a step of calculating this water movement amount H20_m also in this embodiment. Using this information, for example, the sum of the water movement amounts H2O_m in the plurality of small regions belonging to the region A among the plurality of small regions on the membrane electrode assembly 12 is obtained, and the water movement is performed using the value of this sum. The quantity f1 may be estimated.

  Moreover, in Embodiment 2, both the deficiency determination and excess determination of water movement amount are performed. However, the present invention is not limited to this. Only one of the deficiency determination and the excess determination may be used alone. That is, the idea of countermeasures for insufficient water movement by insufficient determination and the idea of countermeasures for excessive water movement by excessive determination can be used individually.

Embodiment 3 FIG.
The control of the second embodiment described above can be executed in various situations including the normal operation of the fuel cell system. However, for example, the situation at the time of system startup or system termination is different from the situation at the time of normal operation. Therefore, in the third embodiment, an appropriate amount of water movement is adjusted according to the operating state of the fuel cell system.

  The third embodiment of the present invention provides suitable adjustment of the amount of water movement when the fuel cell system is started (during startup). The fuel cell system according to the third embodiment of the present invention is a system that can perform the same operation in the same configuration as that of the second embodiment. In the following description, the routine of FIG. 8 will be described as being executed during normal operation of the system for convenience.

  When the system is started, the fuel cell stack 10 is in a low temperature state. It is considered that the situation where the membrane electrode assembly 12 is excessively dried is relatively unlikely to occur under a low temperature condition at the time of startup. Therefore, at the time of start-up, the necessity for increasing the amount of water in the anode in the unit fuel cell 11 to prevent the membrane electrode assembly 12 from being dried is considered not so high. In addition, if the amount of water present on the anode side in the unit fuel cell 11 is excessively large, there is a possibility of causing adverse effects such as so-called flooding in the anode.

  Therefore, in the third embodiment, when the system is started, water movement from the anode side to the cathode side is promoted (increase the water movement amount f1) compared to during normal operation, and conversely, from the cathode side to the anode The water movement toward the side is suppressed (the water movement amount f2 is reduced). By doing so, it is possible to avoid an unnecessary increase in the amount of water on the anode side in the unit fuel cell 11.

  Specifically, in the third embodiment, the values of the target water movement amounts F1 and F2 described in the second embodiment are changed to values different from those during normal operation, and the routine of FIG. 8 is executed when the system is activated. In this embodiment, by multiplying each value of the map of FIG. 8A by a predetermined increase coefficient, the value of the target water movement amount F1 is increased as a whole, and each value of the map of FIG. By multiplying by a predetermined weight loss coefficient, the value of the target water movement amount F2 is reduced as a whole.

  If the value of the target water movement amount F1 increases as a whole, both the determination condition of step S306 and the determination condition of S310 in the routine of FIG. 8 are shifted to the side of increasing the water movement amount f1. Conversely, if the value of the target water movement amount F2 decreases as a whole, both the determination condition in step S314 and the determination condition in S318 in the routine of FIG. 8 are shifted to the side where the water movement amount f2 is decreased. As a result, the water movement amount f1 can be adjusted to be relatively large, and the water movement amount f2 can be adjusted to be relatively small.

  When the transition to the normal operation state is completed after the system is activated, the target water movement amounts F1 and F2 may be returned to the values during the normal operation at an appropriate timing.

  As described above, according to the third embodiment, the water movement amount can be adjusted in accordance with the situation when the fuel cell system is activated.

  In the third embodiment, the values of the target water movement amounts F1 and F2 are changed by multiplying the map values in FIGS. 8A and 8B by the increase coefficient or the decrease coefficient. However, for example, a startup map in which the values of the target water movement amounts F1 and F2 are changed may be individually created and switched to the startup map when the system is started.

Embodiment 4 FIG.
The fourth embodiment according to the present invention is different from the third embodiment in that it has a feature in controlling the warm-up operation of the system. The system of the fourth embodiment has the same configuration as that of the third embodiment and can perform the same operation.

  In Embodiment 3, when the system is started, the amount of water movement is adjusted so that the amount of water on the anode side of the unit fuel cell 11 is relatively small. On the other hand, when the system is warmed up after the system is started, there is a demand for raising the temperature of the fuel cell stack 10 as soon as possible. From such a viewpoint, it is preferable that the amount of water on the anode side of the unit fuel cell 11 is sufficiently increased and the output of the unit fuel cell 11 is secured immediately. This is because the output cannot be secured when the membrane electrode assembly 12 is dry.

  Therefore, in the fourth embodiment, first, the control according to the third embodiment is executed when the system is started. Thereafter, during the warm-up operation of the system, contrary to the third embodiment, water movement from the anode side to the cathode side is suppressed and, conversely, from the cathode side to the anode side, as compared with the normal operation. Promote water movement. By doing so, the amount of water on the anode side in the unit fuel cell 11 can be increased during the warm-up operation of the system.

  Specifically, in the fourth embodiment, contrary to the third embodiment, the value of the target water movement amount F1 is reduced as a whole by multiplying each value of the map of FIG. The value of the target water movement amount F2 is increased as a whole by multiplying each value in the map of FIG. As a result, contrary to the third embodiment, the water movement amount f1 can be adjusted relatively small, and the water movement amount f2 can be adjusted relatively large. Note that the reduction coefficient and the increase coefficient described here do not have to be the same values as the coefficients described in the third embodiment.

  Switching of the target water movement amounts F1 and F2 between the system startup and the system warm-up operation is performed at an appropriate timing such as the state of various system devices and the elapsed time since the system startup. Just do it. After that, when the warm-up operation of the system is completed and the transition to the normal operation state is completed, the target water movement amounts F1 and F2 may be returned to the values during the normal operation at an appropriate timing.

  As described above, according to the fourth embodiment, the amount of water movement can be adjusted in accordance with the situation in which the warm-up operation is performed after the start of the fuel cell system. In the fourth embodiment, as described in the third embodiment, the warm-up operation map may be prepared and switched individually.

Embodiment 5 FIG.
As described above, the third embodiment provides a suitable control at the time of starting the system, and the fourth embodiment provides a suitable control at the time of warming up the system. On the other hand, the fifth embodiment according to the present invention is suitable for the situation at the time of termination (stopping) of the system. It is assumed that the fuel cell system of Embodiment 5 can perform the same operation in the same configuration as that of Embodiment 2.

  There is a demand to stop the system in a state where water remaining in the unit fuel cell 11 (or the fuel cell stack 10) is as small as possible. Furthermore, there is a case where it is desired to stop the system while the remaining water amount is further reduced and both the anode and the cathode of the membrane electrode assembly 12 are sufficiently dried. For example, in a situation where the system can be placed in a cold region, there is a concern that the membrane electrode assembly 12 and various devices of the system may be adversely affected by freezing.

  Therefore, in the fifth embodiment, at the end of the system, the amount of water in the unit fuel cell 11 is reduced by using the following method at the end of the system in order to satisfy the request for reducing the amount of remaining water.

  As described above, the system of the fifth embodiment has the configuration shown in FIG. 1 as in the first to fourth embodiments. In the system of FIG. 1, when the compressor 20 operates, air flows through the cathode gas flow paths 14 of the individual unit fuel cells 11 in the fuel cell stack 10. In the course of this air flow, the moisture in the cathode gas channel 14 and the moisture on the cathode side of the membrane electrode assembly 12 are taken away to the oxidizing gas discharge passage 16.

  Therefore, in the fifth embodiment, by utilizing this point, when the system is terminated, water movement from the anode side to the cathode side in the unit fuel cell 11 is promoted, and water movement from the cathode side to the anode side is suppressed. . Thereby, the water in the unit fuel cell 11 can be collected to the cathode side, and this water can be discharged to the oxidizing gas discharge passage 16.

  Specifically, in the present embodiment, at the end of the system, the values of the target water movement amounts F1 and F2 are changed in the same manner as in the third embodiment (the value of F1 is increased and the value of F2 is decreased). 8 routine is executed. However, the reduction coefficient and the increase coefficient used for changing the target water movement amounts F1 and F2 need not be the same values as the coefficients described in the third embodiment.

  As described above, according to the fifth embodiment, the amount of water movement can be adjusted so as to reduce the amount of remaining water in the unit fuel cell 11 at the end of the fuel cell system. In the fifth embodiment, the system end time map may be prepared separately as described in the third and fourth embodiments. Note that it is also effective to combine the fifth embodiment when a so-called scavenging operation is performed on the cathode side system at the end of the operation of the fuel cell system.

  In the third to fifth embodiments described above, both the target water movement amounts F1 and F2 are changed. However, only one of the values F1 and F2 may be changed. For example, if the target water movement amount F1 is increased, the water movement amount f1 from the anode side toward the cathode side can be increased accordingly. As a result, even if the target water movement amount F2 is not changed, the water movement from the anode side to the cathode side can be increased as compared with the normal operation as a whole.

Embodiment 6 FIG.
Although the fuel cell system according to the sixth embodiment of the present invention has the same system configuration as that of the first to fifth embodiments, the configuration of the membrane electrode assembly 12 is different from that of the first to fifth embodiments.

  As described above, the gas channel outlet having a relatively high humidity and the gas channel inlet having a relatively low humidity are opposed to each other through the membrane electrode assembly 12, so that the arrows f 1 and f 2 in FIG. In this way, water can be moved from the gas channel outlet toward the gas channel inlet. In Embodiment 6, the part (namely, A area | region and C area | region) which concerns in such a water movement among the membrane electrode assemblies 12 is set as the structure different from the site | part (B area | region) of the center side.

  Specifically, in the sixth embodiment, the material for forming the A and C region portions of the membrane electrode assembly 12 has a composition different from that of the material for forming the B region portion, and the material for the A and C region portions is more Use a material with a composition that allows water to move easily. For example, the A and C region portions use an electrolyte material having a higher water permeability coefficient than the B region portion. Thereby, water movement amount f1, f2 can be increased.

  Instead of changing the material, or together with changing the material, the thickness of the A and C region portions of the membrane electrode assembly 12 may be made thinner than the B region portion. This is because if the membrane / electrode assembly 12 is made thinner, water can easily pass therethrough and the amount of water movement can be increased.

  The material and the thickness can be changed with respect to any one of the electrolyte membrane 12a and the catalyst layers 12b and 12c in the membrane electrode assembly 12, or two or more of them. Even when the membrane / electrode assembly has a multilayer structure of three or more layers including layers other than the electrolyte membrane and the electrode catalyst layer, one or more of those layers are targeted and A, What is necessary is just to change the material and thickness of the site | part corresponded to C area | region. Note that “a structure in which water is relatively easy to move” can be rephrased as “a structure in which water is easily exchanged between the anode side and the cathode side”.

  It should be noted that only the idea of the sixth embodiment may be used alone, not the combination with the first to fifth embodiments.

Embodiment 7 FIG.
As described above, the electrolyte has a characteristic that the water permeation characteristic changes according to the surrounding humidity. If the composition of the electrolyte material is different, the amount of increase in water permeation characteristics with respect to the amount of increase in ambient humidity is also different.

  Therefore, in the seventh embodiment, the A and C region portions of the membrane electrode assembly 12 are formed using an electrolyte material whose water permeability coefficient changes more sensitively (largely) with respect to changes in humidity. As a result, when the amount of increase in ambient humidity is the same, the electrolyte material in the A and C region portions has a relatively large increase in water permeability coefficient, and the electrolyte material in the B region portion has an increase in water permeability coefficient. Relatively small. If the amount of increase in water permeation characteristics with respect to the amount of increase in ambient humidity is large, a large effect of promoting water movement can be obtained without greatly reducing the temperature of the coolant.

  With such a configuration, the water movement amounts f1 and f2 can be sufficiently increased without greatly reducing the coolant temperatures ta and tc.

  According to the configuration of the seventh embodiment, at least the following effects can be obtained. As described in the first embodiment, the temperature inside the fuel cell (especially the catalyst layer) during power generation is one of the factors affecting the power generation performance. Even in order to increase the water movement amounts f1 and f2, it is desirable to avoid the temperature of the A and C region portions from being excessively lowered in consideration of the influence on the power generation performance. In this regard, according to the seventh embodiment, it is possible to greatly increase or decrease the water movement amounts f1 and f2 with a small temperature decrease width and temperature increase width. Therefore, the amount of water movement can be adjusted while reducing the influence on the power generation performance.

  Moreover, only the idea of Embodiment 7 can be used individually.

Fuel cell in-plane state estimation method according to Japanese Patent Application No. 2007-138333.
The contents of the estimation method described in Japanese Patent Application No. 2007-138333 will be described below. However, the drawings and reference numerals are appropriately changed from the drawings and reference numerals of Japanese Patent Application No. 2007-138333 in order to avoid confusion with the contents of the present invention described above.

Embodiment 1 of Japanese Patent Application No. 2007-138333
[System configuration of the first embodiment of Japanese Patent Application No. 2007-138333]
FIG. 11 is a diagram for explaining the system configuration of the first embodiment of Japanese Patent Application No. 2007-138333. The system shown in FIG. 11 includes a fuel cell 1010. The fuel cell 1010 includes a plurality of laminated membrane electrode assemblies 1012. The membrane electrode assembly 1012 is a plate-like structure having a spread in the depth direction on the paper surface of FIG.

  An anode and a cathode are formed inside the membrane electrode assembly 1012 with an electrolyte membrane interposed therebetween. On the anode side, there is formed a gas flow path for allowing a fuel gas containing hydrogen (in this embodiment, hydrogen gas) to flow in the plane. In addition, a gas flow path for allowing an oxidizing gas containing oxygen (in this embodiment, air) to flow in the plane is formed on the cathode side. Furthermore, a cooling water passage for circulating the cooling water is formed at the boundary between the individual membrane electrode assemblies. Since the configurations of the fuel cell 1010 and the membrane electrode assembly 1012 are known, further description is omitted here.

  The fuel cell 1010 communicates with an oxidizing gas supply passage 1014 and an oxidizing gas discharge passage 1016. The oxidizing gas supply passage 1014 communicates with the compressor 1020 via the humidifier 1018. The compressor 1020 can supply air sucked through the air filter 1022 to the fuel cell 1010 via the oxidizing gas supply passage 1014.

  The air supplied from the oxidizing gas supply passage 1014 to the fuel cell 1010 is distributed to the cathode-side gas flow path provided in each of the plurality of laminated membrane electrode assemblies 1012. The air distributed in this way flows through the inside of the cathode side of each membrane electrode assembly, and is then discharged from the oxidizing gas discharge passage 1016.

  The fuel cell 1010 generates water on the cathode side when generating electricity by reacting oxygen and hydrogen. For this reason, the gas discharged from the oxidizing gas discharge passage 1016 contains moisture. The humidifier 1018 has a function of humidifying the air on the oxidizing gas supply passage 1014 side using moisture contained in the oxidizing gas discharge passage 1016. Therefore, according to the system shown in FIG. 11, humidified air can be supplied to the cathode side of the fuel cell 1010.

  A fuel gas supply passage 1024 and a fuel gas discharge passage 1026 communicate with the fuel cell 1010. A hydrogen tank 1030 communicates with the fuel gas supply passage 1024 through an adjustment valve 1028. According to this configuration, it is possible to supply hydrogen gas having a desired pressure to the fuel cell 1010 by adjusting the opening of the adjustment valve 1028.

  The hydrogen gas supplied to the fuel cell 1010 is distributed to the anode-side gas flow path provided in each of the laminated membrane electrode assemblies 1012. The hydrogen gas supplied to the anode side flows through the surface of each membrane electrode assembly and is then discharged from the fuel gas discharge passage 1026.

  In the present embodiment, the membrane electrode assembly 1012 has a coflow channel. That is, the cathode-side gas passage and the anode-side gas passage of the membrane electrode assembly 1012 are provided so that the reaction gas flows in the same direction. More specifically, in the state shown in FIG. 11, the membrane electrode assembly 1012 of the present embodiment distributes the fuel gas on the anode side and the oxidizing gas on the cathode side from the top to the bottom of the page. It is configured as follows.

  The fuel cell 1010 further communicates with a cooling water supply passage 1032 and a cooling water discharge passage 1034. The cooling water flowing in from the cooling water supply passage 1032 flows through the boundary of each membrane electrode assembly 1012 and is then discharged from the cooling water discharge passage 1034. The temperature of the fuel cell 1010 is controlled to about 80 ° C., for example, by this cooling water.

  As shown in FIG. 11, the system of this embodiment includes a pressure gauge 1036 and a dew point gauge 1038 in the oxidizing gas supply passage 1014. A pressure gauge 1040 is disposed in the oxidizing gas discharge passage 1016. According to the former pressure gauge 1036 and dew point meter 1038, the pressure and humidity at the cathode side inlet of the membrane electrode assembly 1012 can be detected. According to the latter pressure gauge 1040, the pressure at the cathode side outlet of the membrane electrode assembly 1012 can be detected.

  The system of the present embodiment is further arranged in a pressure gauge 1042 and a dew point meter 1044 arranged in the fuel gas supply passage 1024, a pressure gauge 1046 arranged in the fuel gas discharge passage 1026, and a cooling water discharge passage 1034. A thermometer 1048 is provided. According to these instruments, the pressure and humidity at the anode side inlet of the membrane electrode assembly 1012, the pressure at the anode side outlet, and the temperature of the membrane electrode assembly 1012 can be detected.

  Outputs of the pressure gauges 1036, 1040, 1042, 1046, dew point gauges 1038, 1044, and thermometer 1048 are supplied to an ECU (Electronic Control Unit) 1050. The ECU 1050 can detect the environment related to the pressure and temperature of the membrane electrode assembly 1012 based on the outputs of these instruments.

[Map in ECU]
The system of the present embodiment is characterized in that the power generation distribution of each membrane electrode assembly 1012 provided in the fuel cell 1010 is accurately predicted. The ECU 1050 stores a plurality of maps shown in FIGS. 12 to 14 in order to realize this function.

  FIG. 12 shows a map of current density I. The membrane electrode assembly 1012 generates power at a current density I corresponding to the power generation environment in the plane. FIG. 12 shows a map defining the relationship between the power generation environment surrounding the membrane electrode assembly 1012 and the current density I generated by the membrane electrode assembly 1012.

The power generation state of the membrane electrode assembly 1012 is determined by a plurality of parameters described below. Here, these parameters are collectively referred to as “power generation environment”.
1. Relative humidity of fuel gas flowing through the anode An_RH
2. Relative humidity of oxidizing gas flowing through the cathode Ca_RH
3. Anode pressure P_An
4). Cathode pressure P_Ca
5. 5. Hydrogen concentration in the fuel gas flowing through the anode 6. Oxygen concentration in the oxidizing gas flowing through the cathode Temperature of Membrane / Electrode Assembly 1012 However, “relative humidity” is (vapor pressure) / (saturated vapor pressure) × 100.

  Of the above seven parameters, the pressure P_An of 3 anodes and the pressure P_Ca of 4 cathodes are substantially the same pressure. In addition, the influence of the former on the power generation state is sufficiently smaller than the influence of the latter. For this reason, in the present embodiment, the influence of the anode pressure P_An of 3 is ignored. Of the above parameters, the hydrogen concentration of 5 is almost 100% regardless of the position, and the temperature of 7 is almost the same as the cooling water temperature regardless of the position. For this reason, in this embodiment, the hydrogen concentration of 5 and the temperature of 7 are also handled as constant values.

  FIG. 12 defines the relationship between the power generation environment determined by the remaining four parameters and the current density I. More specifically, FIG. 12A is a map that defines the current density I generated when the cathode pressure P_Ca is 140 Kpa in relation to the anode relative humidity An_RH, the cathode relative humidity Ca_RH, and the oxygen concentration. is there. FIG. 12B is a map in which the current density I generated when the cathode pressure P_Ca is 200 Kpa is defined in relation to the anode relative humidity An_RH, the cathode relative humidity Ca_RH, and the oxygen concentration.

  FIG. 13 is a map in which the relationship between the resistance value R of the membrane electrode assembly 1012 and the power generation environment is defined according to the same rules as in FIG. FIG. 14 is a map that defines the relationship between the amount of water transfer H2O_m from the cathode to the anode of the membrane electrode assembly 1012 and the power generation environment according to the same rule. When the power generation environment of the membrane electrode assembly 1012 is specified, the ECU 1050 predicts the current density I, the resistance value R, and the water transfer amount H2O_m generated in the power generation environment by referring to these maps. Can do.

[How to create a map]
Next, with reference to FIG. 15, a method for creating the maps shown in FIGS. 12 to 14 will be described. The membrane / electrode assembly 1012 shown in FIG. 11 has a sufficiently long distance between a portion where the oxidizing gas flows in and a portion where the oxidizing gas flows out. The same applies to the inflow path of the fuel gas. For this reason, the pressure of the oxidizing gas and the pressure of the fuel gas are not constant in the plane of the membrane electrode assembly 1012.

  Further, the membrane electrode assembly 1012 generates water on the cathode side with power generation. The produced water is caused to flow downstream with the flow of the oxidizing gas. For this reason, the amount of water on the cathode side is not uniform within the surface of the membrane electrode assembly 1012. As a result, a distribution along the gas flow occurs in the cathode-side relative humidity Ca_RH.

  As described above, water moves from the cathode side to the anode side of the membrane electrode assembly 1012. The water thus moved is caused to flow downstream by the flow of the fuel gas. For this reason, even on the anode side, the amount of water is not uniform in the plane. As a result, the anode side relative humidity An_RH also has a distribution along the gas flow.

  Further, the membrane electrode assembly 1012 generates power by consuming oxygen in the air supplied to the cathode. For this reason, the oxygen concentration in the surface of the cathode increases as it approaches the air inlet, and decreases as it approaches the air outlet. As described above, in the membrane electrode assembly 1012, the oxygen concentration on the cathode side is also distributed in the plane.

  In creating the maps shown in FIGS. 12 to 14, it is necessary to specify the power generation environment and measure the results. Among the power generation environments to be specified when creating these maps, the temperature T and the pressure P_Ca can be made relatively easily uniform over the entire surface of the membrane electrode assembly 1012. However, it is difficult to make the anode relative humidity An_RH, the cathode relative humidity Ca_RH, and the oxygen concentration uniform over the entire surface of the membrane electrode assembly 1012 as described above. For this reason, when the full-size membrane electrode assembly 1012 is used, it is difficult to specify the power generation environment. Therefore, in this embodiment, a membrane electrode assembly piece having the same structure as the membrane electrode assembly 1012 except for the size is created, and the map is created using this piece.

  FIG. 15 is a diagram of a system for measuring the power generation state under a specific power generation environment using the membrane electrode assembly piece 1060. The membrane electrode assembly piece 1060 includes a cathode-side gas channel and an anode-side gas channel on both sides of the electrolyte membrane in a co-flow channel relationship. The membrane electrode assembly piece 1060 has a power generation environment from the inlet to the outlet of these gas flow paths, specifically, anode relative humidity An_RH, cathode relative humidity Ca_RH, oxygen concentration, and pressure that can be regarded as uniform. It has a size. Here, from the above viewpoint, the size of the membrane electrode assembly 1060 is 1 cm × 1 cm.

  The system shown in FIG. 15 includes an oxidizing gas supply passage 1062 and an oxidizing gas discharge passage 1064 that communicate with the cathode side of the membrane electrode assembly piece 1060. A compressor 1066 communicates with the oxidizing gas supply passage 1062. The compressor 1066 can supply the air sucked through the air filter 1068 toward the membrane electrode assembly piece 1060.

  A nitrogen tank 1072 communicates with the oxidizing gas supply passage 1062 through an adjustment valve 1072. The nitrogen tank 1072 can supply an amount of nitrogen corresponding to the opening of the adjustment valve 1072 to the oxidizing gas supply passage 1062.

  The oxidizing gas supply passage 1062 includes a bubbler 1074. The bubbler 1074 is a humidifier incorporating a heater 1076 and a thermometer 1078. According to the bubbler 1074, it is possible to create a saturated state of water vapor at a set temperature. For example, if the set temperature is 40 ° C., the oxidizing gas flowing into the membrane electrode assembly piece 1060 can be humidified so as to be saturated at 40 ° C.

  A pressure gauge 1080 and a heater 1082 are disposed downstream of the bubbler 1074. As described above, the membrane electrode assembly piece 1060 has such a size that the pressure distribution inside thereof can be ignored. For this reason, the measured value of the pressure gauge 1080 can be handled as the pressure P_Ca (uniform value) at the cathode of the membrane electrode assembly piece 1060.

  The heater 1082 is provided in order to prevent condensation at the front stage of the membrane electrode assembly piece 1060. According to such a configuration, the oxidizing gas humidified by the bubbler 1074 can be supplied to the membrane electrode assembly piece 1060 at the same humidity. Therefore, according to the system shown in FIG. 15, the humidity of the oxidizing gas supplied to the membrane electrode assembly piece 1060 can be controlled with extremely high accuracy.

  The oxidizing gas supplied to the cathode of the membrane electrode assembly piece 1060 flows out from the oxidizing gas discharge passage 1064. A dew point meter 1084 is provided in the oxidizing gas discharge passage 1064. According to the dew point meter 1084, the humidity of the oxidizing gas flowing out from the membrane electrode assembly piece 1060 can be accurately measured.

  The system shown in FIG. 15 includes a fuel gas supply passage 1086 and a fuel gas discharge passage 1088 that communicate with the anode side of the membrane electrode assembly piece 1060. A hydrogen tank 1092 communicates with the fuel gas supply passage 1086 through an adjustment valve 1090. According to this configuration, by controlling the opening degree of the adjustment valve 1090, hydrogen gas can be supplied to the membrane electrode assembly piece 1060 at a desired pressure.

  The fuel gas supply passage 1086 includes a bubbler 1094 downstream of the adjustment valve 1090. Like the cathode-side bubbler 1074, the bubbler 1094 includes a heater 1096 and a thermometer 1098, and can humidify the fuel gas so as to form a saturated state at a set temperature.

  A pressure gauge 1100 and a heater 1102 are disposed downstream of the bubbler 1094. The measurement value of the pressure gauge 1100 can be handled as the pressure P_An (uniform value) at the anode of the membrane electrode assembly piece 1060. In addition, according to the heater 1102, it is possible to prevent dew condensation at the front stage of the membrane electrode assembly piece 1060. According to such a configuration, the humidity of the fuel gas flowing into the anode of the membrane electrode assembly piece 1060 can be controlled with extremely high accuracy.

  The fuel gas supplied to the anode of the membrane electrode assembly piece 1060 flows out from the fuel gas discharge passage 1088. A dew point meter 1104 is provided in the fuel gas discharge passage 1088. According to the dew point meter 1104, the humidity of the fuel gas flowing out from the membrane electrode assembly piece 1060 can be accurately measured.

  A cooling water supply passage 1106 and a cooling water discharge passage 1108 communicate with the membrane electrode assembly piece 1060. A thermometer 1110 is provided in the cooling water discharge passage 1108. The system shown in FIG. 15 can accurately control the temperature of the cooling water flowing through the membrane electrode assembly piece 1060 by feeding back the measurement value of the thermometer 1110. In this system, the temperature of the cooling water can be handled as the temperature of the membrane electrode assembly piece 1060.

  The system shown in FIG. 15 further includes a measurement circuit 1112 that connects the anode side electrode and the cathode side electrode of the membrane electrode assembly piece 1060. The measurement circuit 1112 includes an ammeter 1114 and a variable resistor 1116. According to this configuration, by adjusting the variable resistor 1116, the potential difference generated between the anode electrode and the cathode electrode is controlled to a desired value (for example, 0.6V or 0.8V), and the membrane electrode bonding is performed. The amount of current (current density I) generated by the small body piece 1060 can be measured.

  As described above, in order to create the maps shown in FIGS. 12 to 14, it is necessary to specify the power generation environment surrounding the membrane electrode assembly. Specifically, it is necessary to specify the anode relative humidity An_RH, the cathode relative humidity Ca_RH, the cathode pressure P_Ca, the hydrogen concentration, the oxygen concentration, and the temperature T.

The anode relative humidity An_RH and the cathode relative humidity Ca_RH can be obtained by the following arithmetic expressions, respectively.
An_RH = (vapor pressure of fuel gas) / (saturated water vapor pressure at temperature T) × 100
... (7)
Ca_RH = (vapor pressure of oxidizing gas) / (saturated water vapor pressure at temperature T) × 100
... (8)

  According to the system shown in FIG. 15, since the cooling water temperature is “temperature T”, the “saturated water vapor pressure” in the second term on the right side can be determined by determining the temperature. According to this system, by changing the temperature of the bubblers 1074 and 1094, the “humidity of fuel gas” in the equation (7) and the “humidity of oxidizing gas” in the equation (8) can be arbitrarily changed. Can do. Therefore, according to the system shown in FIG. 15, the anode relative humidity An_RH and the cathode relative humidity Ca_RH of the membrane electrode assembly 1060 can be accurately and easily controlled to arbitrary values.

  Further, according to the system shown in FIG. 15, the cathode pressure P_Ca can be controlled to an arbitrary value by controlling the operation state of the compressor 1066. Furthermore, by adjusting the amount of nitrogen flowing into the oxidizing gas supply passage 1062 by the adjusting valve 1070, the oxygen concentration in the oxidizing gas flowing into the membrane electrode assembly piece 1060 can be accurately controlled. As described above, according to the system shown in FIG. 15, it is possible to easily and accurately set all the parameters to be specified when setting the maps shown in FIGS.

  Each membrane electrode assembly 1012 shown in FIG. 11 is required to generate a target (about 0.6 V) electromotive force. For this reason, the maps shown in FIGS. 12 to 14 show the “current density I”, “resistance value R”, and “water transfer amount H 2 O_m” under the situation where the membrane electrode assembly 1012 generates the target electromotive force. "Must be defined.

  In the system shown in FIG. 15, the current density I can be measured by the ammeter 1114 while adjusting the electromotive force of the membrane electrode assembly piece 1060 by adjusting the variable resistor 1116. Further, the resistance value R of the membrane electrode assembly piece 1060 can be calculated from the relationship between the current and the voltage at that time. Furthermore, since the amount of water produced at the cathode is proportional to the current density I, the amount of water produced can be calculated if the current density I is known. Then, if the humidity of the oxidizing gas flowing into the cathode (that is, the amount of water), the amount of generated water at the cathode, and the humidity of the oxidizing gas flowing out from the cathode (that is, the amount of water) are known, the membrane electrode assembly piece 1060 is exposed from the cathode. The amount of water H2O_m transferred to the anode can be calculated.

  That is, according to the system shown in FIG. 15, the current density I and the resistance value R can be measured while appropriately changing the power generation environment surrounding the membrane electrode assembly piece 1060, and the water movement amount H 2 O_m can be calculated. . For this reason, if this system is used, the maps shown in FIGS. 12 to 14 can be set very accurately by a simple process.

[Prediction of in-plane state of membrane electrode assembly]
FIG. 16 is a diagram for explaining a virtual dividing method of the membrane electrode assembly 1012 included in the fuel cell 1010 shown in FIG. 11. More specifically, FIG. 16A is a perspective view showing the anode surface of the membrane electrode assembly 1012. Inside the membrane electrode assembly 1012, as described above, a gas flow path for flowing fuel gas or oxidizing gas is formed on both the anode side and the cathode side. In the present embodiment, the gas flow paths form a co-flow flow path, that is, the fuel gas on the anode side and the oxidation gas on the cathode side are transferred from one end of the membrane electrode assembly 1012 to the other end. It is configured to proceed in the same direction (the direction indicated by the arrow in FIG. 16A).

  FIG. 16B shows a part of the membrane electrode assembly 1012 cut out in a band shape (hereinafter referred to as “band-like part 1120”). The membrane electrode assembly 1012 can be virtually regarded as a configuration in which a plurality of the band-like portions 1120 are connected in the vertical direction. In the belt-like portion 1120, the cathode-side oxidizing gas and the anode-side fuel gas flow in parallel with each other in the longitudinal direction as indicated by arrows in FIG.

  As shown in FIG. 16B, the belt-like portion 1120 can be considered to be composed of s small regions arranged in the flow direction of the reaction gas. In the present embodiment, these small regions are assumed to have a size of 1 cm × 1 cm, like the membrane electrode assembly piece 1060 shown in FIG.

  When the membrane electrode assembly 1012 is decomposed into small regions shown in FIG. 16B, the power generation environment can be considered to be uniform in each small region. In this case, if the power generation environment in the n-1th small region (hereinafter referred to as “n-1 region”) is known, the power generation state in that region can be predicted. If the power generation environment and power generation state in the n-1 region are known, the power generation environment in the n region can be predicted. For this reason, considering the membrane electrode assembly 1012 divided into small regions as shown in FIG. 16 (B), if the power generation environment in the first small region is known, then the s region is reached in turn. It is possible to predict the power generation environment and the power generation state in each small area.

  FIG. 17 is a diagram for describing a procedure for predicting the power generation environment in the n region on the basis of the power generation environment in the n−1 region. The oxidizing gas flows into the cathode of the n-1 region from the cathode of the n-2 region, and the water present at the cathode of the n-2 region flows. Here, it is assumed that the oxygen amount O2 (n-1) and the water amount H2O_Ca (n-1) flowing from the n-2 region are known (see reference numeral 1122).

The cathode relative humidity Ca_RH can be calculated from the cathode pressure P_Ca, the cathode water amount H2O_Ca, and the oxidizing gas amount (nitrogen amount N2 + oxygen amount O2) by the following equation.
Ca_RH = [P_Ca × H2O_Ca / {(N2 + O2) + H2O_Ca}] / (saturated water vapor pressure) × 100
... (9)

All parameters included in the right side of the equation (9) can be specified in the n-1 region as follows. Therefore, the cathode relative humidity Ca_RH in the n-1 region can be calculated by using the above equation (9) (see reference numeral 1124).
The cathode pressure P_Ca (n-1) can be obtained by proportional calculation from the measured values of the pressure gauges 1036 and 1040 at the cathode side inlet and outlet of the membrane electrode assembly 1012 (see reference numeral 1125).
-The amount of water H2O_Ca (n-1) is known as described above.
N2 can be calculated from the flow rate of air flowing into the membrane electrode assembly 1012 since it can be regarded as constant in the flow process.
The oxygen amount O2 (n-1) is known as described above.
The saturated water vapor pressure can be specified from the temperature T detected by the thermometer 1048.

The oxygen concentration in the oxidizing gas can be calculated from the nitrogen amount N2 and the oxygen amount O2 according to the following equation.
Oxygen concentration = O2 / (N2 + O2) (10)
Therefore, the oxygen concentration (O2 concentration (n-1)) in the n-1 region is determined by the amount of nitrogen N2 flowing into the membrane electrode assembly 1012 and the amount of oxygen O2 (n-1) flowing in from the n-2 region. (See reference numeral 1126).

  Fuel gas flows into the anode in the n-1 region from the anode in the n-2 region, and water present in the anode in the n-2 region flows into the anode in the n-1 region. Here, it is assumed that the hydrogen amount H2 (n-1) and the water amount H2O_An (n-1) flowing from the n-2 region are known (see reference numeral 1128).

The anode relative humidity An_RH can be calculated from the anode pressure P_An, the anode water amount H2O_An, and the hydrogen amount H2 by the following equation.
An_RH = {P_An × H2O_An / (H2 + H2O_An)} / (saturated water vapor pressure) × 100
(11)

All the parameters included in the right side of the equation (11) can be specified in the n-1 region as follows. Therefore, the anode relative humidity Ca_An in the n-1 region can be calculated by using the above equation (11) (see reference numeral 1130).
The anode pressure P_An (n-1) can be obtained by proportional calculation from the measured values of the pressure gauges 1042 and 1046 at the anode side inlet and outlet of the membrane electrode assembly 1012 (see reference numeral 1131).
The amount of water H2O_An (n-1) and the amount of hydrogen H2 (n-1) are known as described above.
The saturated water vapor pressure can be specified from the temperature T detected by the thermometer 1048.

  When the anode relative humidity An_RH (n-1) (1130), the cathode relative humidity Ca_RH (n-1) (1124), and the O2 concentration (n-1) (1126) are known, the map shown in FIG. The current density I under the cathode pressure P_Ca = 140 kPa can be read out. Further, the current density I under the cathode pressure P_Ca = 200 kPa can be read from the map shown in FIG.

  On the other hand, the cathode pressure P_Ca (n-1) in the n-1 region can be obtained by proportional calculation using the measured values of the pressure gauges 1036 and 1040 as described above. Since the current density I shows a proportional relationship with the cathode pressure P_Ca, the current density I (n-1) in the n-1 region is respectively determined from the maps shown in FIGS. 12 (A) and 12 (B). Based on the read current density I, it can be calculated by proportional calculation (see reference numeral 1132).

  Similarly, the resistance value R in the n−1 region can be calculated by referring to the maps shown in FIGS. 13A and 13B (see reference numeral 1134). Furthermore, by referring to the maps shown in FIGS. 14A and 14B, the water movement amount H2O_m in the n-1 region can be calculated (see reference numeral 1136).

On the cathode side of the membrane electrode assembly 1012, an amount of oxygen corresponding to the current density I is consumed. This oxygen consumption amount O2_off can be calculated by the following equation. However, F in the following equation is a Faraday constant.
O2_off = I / 4 / F × 22.4 × 60 (12)

Accordingly, if the current density I (n-1) in the n-1 region is known, the oxygen consumption O2_0ff (n-1) on the cathode side in that region can be obtained (see reference numeral 1138). The oxygen amount O2 (n) flowing out from the n-1 region and flowing into the n region is consumed in the n-1 region from the oxygen amount O2 (n-1) flowing into the n-1 region. Since the amount is obtained by subtracting the oxygen amount O2_off (n-1), it can be obtained by the following equation (see reference numeral 1140).
O2 (n) = O2 (n-1) -O2_off (n-1) (13)

Further, an amount of water corresponding to the current density I is generated on the cathode side of the membrane electrode assembly 1012. This generated water amount H2O can be calculated by the following equation.
H2O = I / 2 / F × 22.4 × 60 (14)

Therefore, if the current density I (n-1) in the n-1 region is known, the amount of water H2O (n-1) generated at the cathode in that region can be obtained (see reference numeral 1142). The amount of water H2O_Ca (n) flowing out of the n-1 region and flowing into the cathode of the n region is generated in the amount of water H2O_Ca (n-1) flowing into the n-1 region and the n-1 region. This is the amount obtained by subtracting the amount of water H2O_m (n-1) moving from the cathode to the anode in the n-1 region from the sum of the amount of water H2O (n-1) to be obtained, and can be obtained by the following equation (see reference numeral 1144). ).
H2O_Ca (n) = H2O_Ca (n-1) + H2O (n-1) -H2O_m (n-1) (15)

Next, prediction of the power generation state on the anode side will be described. That is, an amount of hydrogen corresponding to the current density I is consumed on the anode side of the membrane electrode assembly 1012. This hydrogen consumption H2_off can be calculated by the following equation.
H2_off = I / 2 / F × 22.4 × 60 (16)

Therefore, if the current density I (n-1) in the n-1 region is known, the hydrogen consumption H2_0ff (n-1) on the anode side in that region can be obtained (see reference numeral 1146). The hydrogen amount H2 (n) flowing out from the n-1 region and flowing into the n region is consumed in the n-1 region from the hydrogen amount H2 (n-1) flowing into the n-1 region. Since the amount is obtained by subtracting the hydrogen amount H2_off (n-1), it can be obtained by the following equation (see reference numeral 1148).
H2 (n) = H2 (n-1) -H2_off (n-1) (17)

The amount of water in the anode increases by the amount of water moving from the cathode side. For this reason, the amount of water H2O_An (n) flowing out of the n-1 region and flowing into the anode of the n region becomes the amount of water H2O_An (n-1) flowing into the n-1 region in the n-1 region. It is the amount of water movement H2O_m (n-1) added. This amount of water H2O_An (n) can be obtained by the following equation (see reference numeral 1150).
H2O_An (n) = H2O_An (n-1) + H2O_m (n-1) (18)

As described above, according to the above processing, if the power generation environment in the n-1 region is known, the power generation state in this region can be predicted. More specifically, if the following values are known, the current density I (n-1), the resistance value R (n-1), and the water movement amount H20_m in the n-1 region can be calculated.
・ Oxygen amount O2 (n-1) and water amount H20_Ca (n-1) flowing into the n-1 cathode
-Hydrogen amount H2 (n-1) and water amount H2O_An (n-1) flowing into the anode in the n-1 region
・ Cathode pressure P_Ca, anode pressure P_An in n-1 region

  Further, when the power generation state predicted by the above processing is reflected in the power generation environment in the n-1 region, the power generation environment in the next n region can be specified. Therefore, according to the above processing, if only the power generation environment in the first small region can be specified, the power generation environment and the power generation state in each small region can be obtained by sequential calculation up to the s region.

  In the system shown in FIG. 11, the oxygen amount O2 (1) flowing into the cathode of the first region is obtained by multiplying the amount of air pumped by the compressor 1020 and the oxygen concentration (known) in the air. Can do. The amount of water H20_Ca (1) flowing into the cathode of the first region can be calculated based on the output of the dew point meter 1038 on the cathode side.

  Further, the hydrogen amount H2 (1) flowing into the anode in the first region can be detected based on the opening degree of the adjustment valve 1028 or the like. The amount of water H2O_An (1) flowing into the anode in the first region can be calculated based on the output of the dew point meter 1044 on the anode side.

  Further, the cathode pressure P_Ca in the first region can be calculated by performing proportional calculation based on the output of the pressure gauge 1036 at the cathode inlet and the output of the pressure gauge 1040 at the cathode outlet. Similarly, the anode pressure P_An in the first region can be calculated by performing proportional calculation based on the output of the pressure gauge 1042 at the anode inlet and the output of the pressure gauge 1046 at the anode outlet.

  Thus, according to the system shown in FIG. 11, it is possible to obtain all the numerical values necessary for predicting the power generation state in the first region. Therefore, in the system according to the present embodiment, it is possible to predict by calculation what kind of power generation state, under what kind of power generation environment, each region 1 to s of the membrane electrode assembly 1012 is. .

[Specific Processing in Embodiment 1 of Japanese Patent Application No. 2007-138333]
FIG. 18 is a flowchart of a routine that the ECU 1050 executes in order to implement the above processing. In the routine shown in FIG. 18, first, 1 is set in the region number n (step 1160).

  Next, the cathode state quantity of region n is calculated (step 1162). Specifically, the oxygen amount O2 (n) and the water amount H20_Ca (n) flowing into the cathode are calculated for the region where n = 1 (see reference numeral 1122 in FIG. 17). Next, the cathode pressure P_Ca (n) is calculated by proportional calculation based on the outputs of the pressure gauges 1036 and 1040 (see reference numeral 1125 in FIG. 17). Further, the cathode relative humidity Ca_RH (n) is calculated according to the above equation (9), and the oxygen concentration O2 concentration (n) of the cathode is calculated according to the above equation (10) (see reference numerals 1124 and 1126 in FIG. 17). ).

  In the routine shown in FIG. 18, next, the anode state quantity of the region n is calculated (step 1164). Specifically, hydrogen H2 (n) and water amount H20_An (n) flowing into the anode are calculated for the region where n = 1 (see reference numeral 1128 in FIG. 17). Next, the anode pressure P_An (n) is calculated by proportional calculation based on the outputs of the pressure gauges 1042 and 1046 (see reference numeral 1131 in FIG. 17). Further, the anode relative humidity An_RH (n) is calculated according to the above equation (11) (see reference numeral 1130 in FIG. 17).

  Next, the power generation state in the n region is calculated (step 1166). Specifically, first, the current density I is read from the map shown in FIG. 12A and the map shown in FIG. Next, from the map shown in FIG. 12A, the current density I when the cathode pressure P_Ca is 140 kPa is read. In addition, the current density I when the cathode pressure P_Ca is 200 kPa is read from the map shown in FIG. In this step, the current density I corresponding to the cathode pressure P_Ca (n) is calculated by performing proportional calculation on these map values (see reference numeral 1132 in FIG. 17).

  In step 1166, the resistance value R (n) is calculated with reference to the map shown in FIG. 13A and the map shown in FIG. 13B (see reference numeral 1134 in FIG. 17). Furthermore, here, the water movement amount H2O_m (n) is calculated with reference to the map shown in FIG. 14A and the map shown in FIG. 14B (see reference numeral 1136 in FIG. 17). Since the method of calculating the resistance value R (n) and the water movement amount H2O_m (n) according to the cathode pressure P_Ca (n) from the two map values is the same as that in the case of the current density I, the details are described here. Omitted.

  Next, the generation / consumption amount in the n region is calculated (step 1168). Specifically, the amount of oxygen O2_off (n) consumed on the cathode side is calculated according to the above equation (12), and the amount of generated water H2O (n) is calculated according to the above equation (14) ( In FIG. 17, reference numerals 1138 and 1142). Further, the amount of hydrogen H2_off (n) consumed on the anode side is calculated according to the above equation (1010) (see reference numeral 1146 in FIG. 17).

  When the above processing is completed, it is determined whether the region number n has reached the final value s (step 1170). As a result, when it is determined that n has not reached s, after n is incremented (step 1172), the processing after step 1162 is executed again.

  When n is 2 or more, in step 1162, the oxygen amount O2 (n) and the water amount H2O_Ca of the cathode are calculated according to the above equation (13) or (15), respectively (see reference numerals 1140 and 1144 in FIG. 17). ). In this case, in step 1164, the hydrogen amount H2 (n) and the water amount H2O_An of the anode are calculated according to the above equation (17) or (18), respectively.

  Thereafter, the above process is repeatedly executed until it is determined in step 1170 that n = s is established. As a result, the power generation environment and the power generation state are calculated in all regions from the first region to the s region. That is, according to the above processing, the power generation environment and the power generation state distribution of the membrane electrode assembly 1012 can be predicted using the small region as a mesh unit.

  By the way, in Embodiment 1 of the above-mentioned Japanese Patent Application No. 2007-138333, the temperature of the membrane electrode assembly 1012 is assumed to be uniform over the entire surface, but the invention described in the Japanese Patent Application No. 2007-138333 is not limited to this. It is not limited to. That is, when the temperature of the membrane electrode assembly 1012 has a distribution in the plane, the distribution of the power generation state may be predicted in consideration of the distribution. The prediction considering the temperature distribution can be realized by the following method, for example.

  A map relating to the current density I, the resistance value R, and the water movement amount H2O_m is prepared for each of a plurality of temperatures. Each map is set by changing the temperature of the membrane electrode assembly piece 1060 (see FIG. 15) and measuring the current density I, the resistance value R, and the water movement amount H2O_m. The temperature in each small region of the membrane electrode assembly 1012 is predicted by reflecting the amount of heat generated in the region in the temperature of the small region located upstream of the flow of the reaction gas. The calorific value is calculated based on the current density I in the region. Once the temperature of the area is known, the current density I, resistance value R, and water transfer amount H2O_m corresponding to the temperature of the area are calculated by proportional calculation based on the map values read from multiple maps prepared for each temperature. To do.

  Further, in the first embodiment of the above-mentioned Japanese Patent Application No. 2007-138333, the distribution of the resistance value R of the membrane electrode assembly 1012 is also predicted. However, the prediction of the resistance value R is omitted if not necessary. May be.

  In the first embodiment of the above-mentioned Japanese Patent Application No. 2007-138333, the measurement using the membrane electrode assembly piece 1012 (see FIG. 15) is performed in order to simplify the map setting operation. The method for setting the maps shown in FIGS. 12 to 14 is not limited to this. For example, the map setting operation may be performed using the membrane electrode assembly 1012 as a measurement target.

  In the first embodiment of the above-mentioned Japanese Patent Application No. 2007-138333, a dew point meter 1044 is also arranged at the inlet on the anode side in preparation for supplying humidified hydrogen gas to the anode of the fuel cell 1010. However, the present invention is not limited to this. That is, when the fuel gas supplied to the anode is not humidified, the dew point meter 1044 may be omitted.

  In the first embodiment of Japanese Patent Application No. 2007-138333 described above, in order to predict the anode pressure P_An, the pressure gauges 1042 and 1046 are arranged at two locations of the inlet and the outlet. The invention described in No. 138333 is not limited to this. That is, the pressure distribution inside the membrane electrode assembly 1012 can be estimated if the pressure is known on one of the inlet and the outlet. For this reason, the pressure gauge on the anode side may be disposed only on either the inlet side or the outlet side. The same applies to the pressure gauge on the cathode side.

Embodiment 2 of Japanese Patent Application No. 2007-138333
Next, a second embodiment of Japanese Patent Application No. 2007-138333 will be described with reference to FIGS. The hardware configuration of this embodiment is the same as the configuration shown in FIG. 11 except that the oxidizing gas channel and the fuel gas channel of the membrane electrode assembly 1012 are configured to form a counter channel. is there. The system of the present embodiment can be realized by causing the ECU 1050 to execute a routine shown in FIG. 21 described later in such a hardware configuration.

  As described above, in the system of Embodiment 1 of Japanese Patent Application No. 2007-138333, the oxidizing gas flow path and the fuel gas flow path of the membrane electrode assembly 1012 form a co-flow flow path. That is, in Embodiment 1 of Japanese Patent Application No. 2007-138333, the cathode side oxidizing gas and the anode side fuel gas flow in the same direction. In this case, the power generation environment and power generation state in the n-1 region determine the power generation environment in the n region on both the anode side and the cathode side. Therefore, in the system of the first embodiment of Japanese Patent Application No. 2007-138333, it is possible to predict the power generation environment and the power generation state in the first region based on the state of the anode inlet and the state of the cathode inlet. After that, it is possible to sequentially predict the power generation environment and the power generation state for each small region until reaching the s region.

  However, when the cathode-side fuel passage and the anode-side fuel passage form a counter passage, if the cathode inlet is connected to the first region, the anode inlet is connected to the s region. . In this case, on the cathode side, the state of the n-1 region determines the state of the n region, and on the anode side, the state of the n + 1 region determines the state of the n region.

  For example, if prediction is started from a small region adjacent to the inlet in both the cathode and the anode, the power generation state of the first small region is first predicted on the cathode side based on the state of the cathode inlet. On the other hand, on the anode side, at the timing, the power generation state of the s region is predicted based on the state of the anode inlet. That is, at this timing, for the first region, the cathode-side power generation environment can be predicted, but the anode-side power generation environment cannot be predicted. The opposite situation occurs in the s region.

  As described with reference to FIG. 17, the current density I (n−1), the resistance value R (n−1), the water transfer amount H 2 O_m (n−1) in a certain small region (referred to as the (n−1) region). ) Cannot be predicted unless both the cathode-side environment and the anode-side environment in that region are specified. If the current density I (n-1) and the water transfer amount H2O_m (n-1) are not determined, the oxygen consumption amount O2_off (n-1) and the hydrogen consumption amount H2_off (n-1) in the (n-1) region ), And the amount of water produced H2O (n-1) cannot be predicted. For this reason, when the oxidizing gas passage and the fuel gas passage form a counter passage, the power generation environment and the power generation state are determined for all of the plurality of small regions according to the same technique as in the first embodiment of Japanese Patent Application No. 2007-138333. Cannot be predicted sequentially.

  19 and 20 are diagrams for explaining a method for predicting the power generation environment and the power generation state of each small area when the oxidizing gas passage and the fuel gas passage form a counter flow path. More specifically, FIG. 19 is a diagram for explaining a technique for sequentially predicting the power generation environment and the power generation state on the cathode side. FIG. 20 is a diagram for explaining a method for sequentially predicting the power generation environment and the power generation state on the anode side.

  In the present embodiment, the ECU 1050 has a cathode memory region (see FIGS. 19A and 20C) and an anode memory region (see FIGS. 19C and 20A). The cathode memory area is an area for storing the cathode relative humidity Ca_RH and the O2 concentration in each small area. On the other hand, the anode memory area is an area for storing the anode relative humidity An_RH in each small area.

  As shown in FIG. 19, the ECU 1050 stores anode relative humidity An_RH corresponding to each small area in the anode memory area. As described with reference to FIG. 17, the current density I (i), resistance value R (i), and water transfer amount H 2 O_m (i) of a small region (referred to as i region) are added to the power generation environment on the cathode side. Thus, if the anode relative humidity An_RH (i) can be specified, it can be calculated. Therefore, if the power generation environment on the cathode side in the i region can be identified, the anode relative humidity An_RH (i) is read from the anode memory region, thereby predicting the power generation state in the i region and further positioned in the next stage ( It is possible to predict the power generation environment in the i + 1) region. By repeating this process, the power generation environment and the power generation state in all the small areas can be sequentially predicted from the first small area to the s area.

  In the present embodiment, the ECU 1050 calculates the power generation environment on the cathode side in each small region and the power generation state in each small region in the order along the flow of the oxidizing gas on the cathode side by the method described above. In the process of this calculation, the cathode relative humidity Ca_RH (i) and the O2 concentration (i) are calculated in each small region (i). As shown in FIG. 19, the ECU 1050 uses the cathode relative humidity Ca_RH (i) and the O2 concentration (i) calculated in this way as the next stage data, that is, as the data of the i + 1 area, the cathode memory area. To remember.

  FIG. 20 shows a procedure in which the ECU 1050 sequentially calculates the anode-side state using the cathode relative humidity Ca_RH and the O2 concentration stored in the cathode memory area. In other words, ECU 1050 can determine current density I (i), resistance value R (i), and water transfer amount if the cathode relative humidity Ca_RH (i) and O2 concentration (i) can be specified together with the power generation environment on the anode side in the i region. H2O_m (i) can be calculated. For this reason, if the power generation environment on the anode side in the i region can be specified, the cathode relative humidity Ca_RH (i) and the O2 concentration (i) are read from the cathode memory region, thereby predicting the power generation state in the i region, It is possible to predict the power generation environment in the (i-1) region located in the preceding stage. Then, by repeating this process, it is possible to sequentially predict the power generation environment and the power generation state in all the small regions from the s region to the first region.

  In the present embodiment, the ECU 1050 calculates the power generation environment on the anode side in each small region and the power generation state in each small region in the order along the flow of the fuel gas on the anode side by the method described above. In the process of this calculation, the anode relative humidity An_RH (i) is calculated in each small region (i). As shown in FIG. 20, the ECU 1050 stores the anode relative humidity An_RH (i) thus calculated in the anode memory area as the previous stage data, that is, as the data of the i-1 area.

  As described above, in the present embodiment, the ECU 1050 executes the process of sequentially predicting the power generation environment and the power generation state on both the cathode side and the anode side in parallel. Then, the processing on the cathode side is executed using the anode relative humidity An_RH stored in the anode memory area one cycle before. On the other hand, the processing on the anode side is performed using the cathode relative humidity Ca_RH and the O2 concentration stored in the cathode memory area one cycle before.

  Therefore, at time t1, on the cathode side, prediction processing using the cathode-side power generation environment at time t1 and the anode relative humidity An_RH at time t0 that is one cycle back from time t1 is executed. Similarly, on the anode side, prediction processing based on the power generation environment on the anode side at time t1 and the cathode relative humidity Ca_RH and O2 concentration at time t0 is executed.

  In this embodiment, in order to eliminate the influence of the time difference described above, the cathode relative humidity Ca_RH (i) and the O2 concentration (i) obtained in the i region are stored in the cathode memory region as data in the (i + 1) region. . On the cathode side, with the flow of the oxidizing gas, there occurs a situation in which the state of the i region shifts to the subsequent stage side as time passes. For this reason, if the data obtained in the i area is stored as the data in the i + 1 area, the influence of the time difference of one cycle described above can be suppressed. For the same reason, according to the method of this embodiment, the influence of the time difference for one cycle can be sufficiently suppressed even on the anode side. Therefore, according to the system of the present embodiment, the power generation environment and the power generation state can be predicted with high accuracy by the cathode-side process and the anode-side process, respectively.

  FIG. 21 is a flowchart of a routine executed by the ECU 1050 in the present embodiment. In the routine shown in FIG. 21, first, an area number is initialized (step 1180). Specifically, 1 is set in the region number n indicating the processing target on the cathode side. Further, s is set in the region number N indicating the processing object on the anode side.

  Next, the cathode state quantity of the n region (first region) is calculated (step 1182). In step 1182, the oxygen amount O2 (n), water amount H2O_Ca (n), cathode relative humidity Ca_RH (n), O2 concentration (n), and cathode pressure P_Ca (at the cathode) are the same as those in step 1162 shown in FIG. n) is calculated (see reference numerals 1122, 1124, 1125, 1126 in FIG. 17).

  Next, the anode relative humidity An_RH (n) corresponding to the n region is read from the anode memory region (step 1184).

  Next, the power generation state in the n region is calculated (step 1186). As described with reference to FIG. 17, when the anode relative humidity An_RH (n) (see reference numeral 1130 in FIG. 17) is determined in addition to the power generation environment on the cathode side, the current shown in FIG. 12 to FIG. The density I (n), the resistance value R (n), and the water movement amount H2O_m (n) can be read out. Here, those values are read from the map based on the parameters specified by the processing of steps 1182 and 1184.

  Next, the amount of oxygen O2_off (n) consumed on the cathode side and the amount of water H2O (n) produced on the cathode side are calculated (step 1188). The oxygen consumption amount O2_off (n) is calculated according to the above equation (12). Further, the water generation amount H2O (n) is calculated according to the above equation (14) (see reference numerals 1138 and 1142 in FIG. 17).

  Next, the anode state quantity of the N region (s region) is calculated (step 1190). In this step 1190, the hydrogen amount H2 (N), the water amount H2O_An (N), the anode relative humidity An_RH (N), and the anode pressure P_Ca (N) at the anode are calculated by the same processing as step 1164 shown in FIG. (Refer to reference numerals 1128, 1130, and 1131 in FIG. 17).

  Next, the cathode relative humidity Ca_RH (N) corresponding to the N region is read from the cathode memory region (step 1192). Further, the cathode pressure P_Ca (N) is calculated based on the outputs of the pressure gauges 1036 and 1040 on the cathode side (step 1193).

  Subsequently, the power generation state in the N region is calculated (step 1194). As described with reference to FIG. 17, in addition to the power generation environment on the anode side, if the cathode relative humidity Ca_RH (N), the cathode pressure P_Ca (N), and the O2 concentration (N) are determined (reference numeral 1124 in FIG. 17). 1125 and 1126), the current density I (N), the resistance value R (N), and the water movement amount H2O_m (N) can be read from the maps shown in FIGS. Here, those values are read from the map based on the parameters specified by the processing of steps 1190 to 1193.

  Next, the amount of hydrogen H2_off (N) consumed on the anode side is calculated (step 1196). The hydrogen consumption amount H2_off (N) is calculated according to the above equation (16) (see reference numeral 1146 in FIG. 17).

  When the above processing is completed, it is determined whether the cathode-side region number n has reached s and the anode-side region number N has reached 1 (step 1198). As a result, if this determination is negative, after n is incremented and N is decremented (step 1200), the processing from step 1182 onward is executed again.

  When n is 2 or more, in step 1182, the oxygen amount O 2 (n) and water amount H 2 O_Ca of the cathode are calculated according to the above equation (13) or (15), respectively (see reference numerals 1140 and 1144 in FIG. 17). ). In this case, in Step 1190, the hydrogen amount H2 (n) and the water amount H2O_An of the anode are calculated according to the above equation (17) or (18), respectively.

  Thereafter, in step 1198, the above processing is repeatedly executed until it is determined that n = s and N = 1. As a result, the power generation environment and the power generation state are calculated in all regions from the first region to the s region.

  When the above processing is repeated and one cycle of processing is completed on both the cathode side and the anode side, the condition of step 1198 is satisfied. In this case, the ECU 1050 next stores the cathode relative humidity Ca_RH (i) and the O2 concentration (i) of the i region (i = 1 to s) in the cathode memory region as data of the (i + 1) region ( Step 1202).

  Further, the ECU 1050 stores the anode relative humidity An_RH (i) of the i area (i = 1 to s) in the anode memory area as data of the (i-1) area (step 1204). With the above process, the process described with reference to FIG. 19 is realized. As a result, preparations for accurately predicting the power generation environment and the power generation state are prepared on both the cathode side and the anode side during the next processing cycle.

  According to the routine shown in FIG. 21, in step 1186, a power generation state in which the power generation environment on the cathode side is reflected in real time is calculated. In Step 1194, the power generation state in which the anode-side power generation environment is reflected in real time is calculated. These two power generation states eventually converge to substantially the same value as the prediction calculation is repeated. The distribution of the power generation environment and the power generation state at the time when both converge to the same value can be recognized as a distribution in the steady state. For this reason, when using the system of the present embodiment, the prediction calculation may be terminated when the power generation state obtained in step 1186 and the power generation state obtained in step 1194 become equal.

  FIG. 22 shows the result of distribution prediction executed by the system of this embodiment. In FIG. 22, for example, the O2 concentration decreases almost proportionally as the distance from the cathode entrance increases. In addition, the current density I tends to increase and then decrease as the distance from the cathode entrance increases. These coincide with the tendency that actually occurs in the membrane electrode assembly 1012 with high accuracy. The same applies to other values shown in FIG. 22 (resistance value R, anode relative humidity An_RH, cathode relative humidity Ca_RH). As these prediction results indicate, the system of the present embodiment can accurately predict the distribution generated in the plane of the membrane electrode assembly 1012.

It is a figure which shows the structure of the system of Embodiment 1 of this invention. It is sectional drawing of the unit fuel cell 11 of Embodiment 1 of this invention. It is a top view of the unit fuel cell 11 of Embodiment 1 of this invention. 3 is an image of an estimated humidity distribution obtained as a result of the ECU 58 executing a routine for estimating the in-plane state of the fuel cell in the first embodiment of the present invention. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a map used with the system of Embodiment 1 of this invention. It is a modification of the system of Embodiment 1 of this invention. It is a flowchart of the routine performed in the system of Embodiment 2 of this invention. It is a map used with the system of Embodiment 2 of this invention. It is a map used with the system of Embodiment 2 of this invention. It is a figure for demonstrating the structure of the system of Embodiment 1 of Japanese Patent Application No. 2007-138333. The map of the current density I which the system of Embodiment 1 of Japanese Patent Application No. 2007-138333 uses is shown. The map of resistance value R which the system of Embodiment 1 of Japanese Patent Application No. 2007-138333 uses is shown. The map of water movement amount H2O_m which the system of Embodiment 1 of Japanese Patent Application No. 2007-138333 uses is shown. It is a figure of the system for measuring the electric power generation state in a specific electric power generation environment using a membrane electrode assembly piece. It is a figure for demonstrating the virtual division | segmentation method of the membrane electrode assembly with which the fuel cell shown in FIG. 11 is provided. It is a figure for demonstrating the procedure in which the system of Embodiment 1 of Japanese Patent Application No. 2007-138333 estimates the power generation environment in n area | region based on the power generation environment in n-1 area | region. It is a flowchart of the routine performed in the system of Embodiment 1 of Japanese Patent Application No. 2007-138333. It is a figure for demonstrating the content of the process performed by the cathode side in Embodiment 2 of Japanese Patent Application No. 2007-138333. It is a figure for demonstrating the content of the process performed by the anode side in Embodiment 2 of Japanese Patent Application No. 2007-138333. It is a flowchart of the routine performed in the system of Embodiment 2 of Japanese Patent Application No. 2007-138333. It is a figure which shows the result of the distribution prediction by the system of Embodiment 2 of Japanese Patent Application No. 2007-138333.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell stack 11 Unit fuel cell 12 Membrane electrode assembly 12a Solid polymer electrolyte membrane 12b Electrode catalyst layer 12c Electrode catalyst layer 13 Gas flow path (anode gas flow path)
13a Anode gas channel inlet 13b Anode gas channel outlet 14 Gas channel (cathode gas channel)
14a Cathode gas passage inlet 14b Cathode gas passage outlets 15a, 15b, 15c Coolant passage 16 Oxidizing gas discharge passage 17 Oxidizing gas supply passage 18 Coolant manifold 20 Compressor 22 Air filter 24 Fuel gas supply passage 26 Fuel gas discharge passage 28 Adjustment valve 30 Hydrogen tank 36, 40, 42, 46 Pressure gauge 38, 44 Dew point meter 48 Thermometer 50 Cooling system 50a, 50b, 50c Cooling fluid passage 51 Radiator 52 Pump 53, 54 Heat exchanger 55, 56, 57 Thermometer

Claims (9)

A membrane electrode assembly having a catalyst layer on both sides of the electrolyte membrane, a first gas channel provided in contact with one surface of the membrane electrode assembly, and in contact with the other surface of the membrane electrode assembly A fuel cell, wherein an inlet side portion of the first gas channel and an outlet side portion of the second gas channel are opposed to each other with the membrane electrode assembly interposed therebetween, ,
An area on the inlet side of the first gas flow path on the surface on the first gas flow path side of the fuel cell, and an area on the outlet side of the second gas flow path on the surface on the second gas flow path side of the fuel cell. A first refrigerant passage having an inlet and having a refrigerant flowing therein during power generation of the fuel cell;
The fuel cell is provided in a central region of at least one of the first gas flow path side surface and the second gas flow path side surface, and includes an inlet different from the inlet of the first refrigerant passage. A second refrigerant passage through which refrigerant flows during power generation of the fuel cell;
Refrigerant supply means for supplying refrigerant to the respective inlets of the first and second refrigerant passages;
An adjustment mechanism capable of adjusting the temperature or flow rate of the refrigerant flowing into the inlet of the first refrigerant passage independently of the temperature or flow rate of the refrigerant flowing into the inlet of the second refrigerant passage;
A fuel cell system comprising: Shortage determination means for determining whether or not the amount of water movement to the inlet side portion of the first gas flow path is insufficient;
If it is determined by the shortage determining means that the amount of water movement is insufficient, the temperature of the refrigerant flowing into the inlet of the first refrigerant passage is decreased, and / or the flow rate of the refrigerant is increased. Cooling control means for controlling the adjusting mechanism;
The fuel cell system according to claim 1, comprising: An inlet-side humidity acquisition means for acquiring, by measurement or estimation, a first gas channel inlet humidity that represents the humidity of the inlet side portion of the first gas channel;
The deficiency determining means determines that the amount of water movement to the inlet side portion of the first gas channel is insufficient when the humidity at the inlet of the first gas channel is below a predetermined lower limit value. The fuel cell system according to claim 2. Water movement amount acquisition means for acquiring a water movement amount from the outlet side portion of the second gas flow path toward the inlet side portion of the first gas flow path through the electrolyte membrane;
The shortage determination means determines that the amount of water movement to the inlet side portion of the first gas channel is insufficient when the water movement amount acquired by the water movement amount acquisition means falls below a predetermined lower limit value. The fuel cell system according to claim 2, wherein: The water movement amount acquisition means is
A gas flow path environment acquisition means for measuring or estimating the humidity, temperature and pressure of the inlet side portion of the first gas flow path and the humidity, temperature and pressure of the outlet side portion of the second gas flow path;
Water movement characteristics storing water movement characteristics that define the relationship between the environment around the electrolyte membrane and the amount of water movement from the second gas flow path side surface of the electrolyte membrane to the first gas flow path side surface Storage means;
Using the acquired value acquired by the gas flow path environment acquiring unit, according to the water transfer characteristic, an estimation calculation unit that estimates and calculates a water movement amount;
The fuel cell system according to claim 4, comprising: Inlet-side humidity acquisition means for acquiring, by measurement or estimation, a first gas-channel inlet humidity representing the humidity of the inlet-side portion of the first gas channel;
Outlet side humidity obtaining means for obtaining, by measurement or estimation, a second gas passage outlet humidity representing the humidity of the outlet side portion of the second gas passage;
Environmental determination means for determining whether a difference between the first gas flow path inlet humidity and the second gas flow path outlet humidity is greater than a predetermined determination value;
The cooling control means controls the adjustment mechanism when it is determined that the amount of water movement is insufficient by the shortage determination means and the difference is determined to be larger than the determination value by the environment determination means. The fuel cell system according to claim 2, wherein the fuel cell system is a fuel cell system. Excess determination means for determining whether the amount of water movement to the inlet side portion of the first gas flow path is excessive;
If it is determined by the shortage determining means that the amount of water movement is excessive, the temperature of the refrigerant flowing into the inlet of the first refrigerant passage rises and / or the flow rate of the refrigerant decreases. A temperature rise control means for controlling the adjustment mechanism;
The fuel cell system according to any one of claims 1 to 6, further comprising:   The membrane electrode assembly has a specific portion sandwiched between an inlet side portion of the first gas flow channel and an outlet side portion of the second gas flow channel in a plane as compared to a central portion in the plane. The fuel cell system according to claim 1, wherein water easily permeates in a thickness direction.   The specific portion sandwiched between the inlet side portion of the first gas flow path and the outlet side portion of the second gas flow path in the plane of the membrane electrode assembly is a central side in the plane of the membrane electrode assembly. The fuel cell system according to any one of claims 1 to 8, wherein an increase amount of water permeation with respect to an increase amount of ambient humidity per unit area is larger than a region.

Images