JP2010118172A - Separator, fuel cell, fuel cell system, method for controlling the fuel cell system - Google Patents

Abstract

The start performance of a fuel cell in a low temperature environment is greatly improved by efficiently raising the temperature around the gas inlet of the fuel cell.
SOLUTION: An oxidizing gas inlet side manifold 13 for introducing an oxidizing gas from the outside to a first surface 11a disposed close to a power generator of a fuel cell, and an oxidizing gas discharged from the first surface 11a to the outside. An oxidant gas outlet side manifold 15, a refrigerant inlet side manifold 17 for supplying refrigerant from the outside to the second surface 11c arranged on the opposite side of the power generator, and a refrigerant from the second surface 11c to the outside. A separator 11 including a refrigerant outlet side manifold 18 for discharging, and suppressing heat transfer between a region A _IN around the oxidizing gas inlet side manifold 13 and a region A _OUT around the oxidizing gas outlet side manifold 15. Heat transfer suppression means 19 is provided.
[Selection] Figure 4

Description

  The present invention relates to a separator, a fuel cell, a fuel cell system, and a control method for the fuel cell system.

  Conventionally, a solid / electrode assembly (MEA) formed by providing a catalyst layer for electrodes on both surfaces of a hydrogen ion conductive electrolyte membrane and a separator sandwiching the MEA A polymer electrolyte fuel cell has been proposed and put into practical use. In a fuel cell system including such a fuel cell, a fuel gas such as hydrogen gas is applied to one electrode (anode electrode) constituting the MEA of the fuel cell, and an oxidizing gas such as air is applied to the other electrode (cathode electrode). It generates electricity by supplying it and causing an electrochemical reaction. At present, a technique is adopted in which a plurality of fuel cells (single cells) having a single MEA are stacked to form a stacked body (stack) to generate large electric power.

A separator constituting a solid polymer electrolyte type fuel cell includes a gas flow path provided on a surface facing the MEA, a manifold for allowing a reaction gas (fuel gas or oxidizing gas) to flow from the outside to the gas flow path, and The plate-shaped member which has these. Such a separator separates the stacked unit cells and prevents the fuel gas and the oxidizing gas from mixing between the adjacent unit cells, and the refrigerant channel and the gas channel provided between the adjacent unit cells. And a function of electrically connecting adjacent single cells. In recent years, a separator in which a refrigerant channel is formed on the back surface of a gas channel has been proposed (see, for example, Patent Document 1).
JP 2000-1000045 A

  By the way, it is known that the power generation performance of a fuel cell deteriorates in a low temperature environment such as below freezing point. The reason for this is that before the temperature of the fuel cell rises due to reaction heat during power generation and exceeds the freezing point (zero degrees Celsius), the water generated during power generation fills the voids of the catalyst layer constituting the fuel cell, and the catalyst layer This is because the moisture in the inside freezes. In particular, in the area around the oxidant gas outlet of the fuel cell, in addition to the generated water during power generation, the water that has moved from the oxidant gas inlet with the circulation of the oxidant gas stays and the water content of the catalyst layer increases. The power generation performance in a low temperature environment was further deteriorated.

  In contrast, the area around the oxidant gas inlet of the fuel cell has a relatively low water content in the catalyst layer due to the moisture removal effect caused by the flow of oxidant gas. In particular, the temperature is likely to rise until it exceeds the freezing point, and power generation continuity in a low temperature environment is good. However, in a fuel cell employing a conventional separator as described in Patent Document 1, the reaction heat generated in the oxidant gas inlet peripheral region is diffused in the oxidant gas outlet peripheral region. It has been difficult to raise the temperature efficiently.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to significantly improve the starting performance of a fuel cell in a low temperature environment by efficiently raising the temperature around the gas inlet of the fuel cell. .

  In order to achieve the above object, a separator according to the present invention supplies a reaction gas (for example, air as an oxidizing gas) to a first surface disposed close to a power generator of a fuel cell and to the first surface from the outside. A gas inlet side manifold for discharging the reaction gas from the first surface to the outside, a second surface disposed on the opposite side of the power generator, and a second surface from the outside A refrigerant inlet side manifold for supplying the refrigerant and a refrigerant outlet side manifold for discharging the refrigerant from the second surface to the outside, and the reaction gas supplied from the outside flows along the first surface On the other hand, a separator for a fuel cell configured such that an externally supplied refrigerant flows along the second surface, and includes a region around a gas inlet side manifold and a region around a gas outlet side manifold. Heat transfer between Those with suppressing heat transfer suppressing means.

  By adopting such a configuration, it is possible to suppress heat transfer between the gas inlet peripheral region (region around the gas inlet side manifold) and the gas outlet peripheral region (region around the gas outlet side manifold) of the separator. The diffusion of heat generated in the entrance peripheral region can be suppressed. Accordingly, since the temperature around the gas inlet of the separator can be effectively raised, the temperature around the gas inlet of the power generator arranged close to the separator can be raised efficiently, and the fuel cell in a low temperature environment can be heated. Startability can be greatly improved.

  In the separator, a heat insulating member as a heat transfer suppressing means can be disposed between a region around the gas inlet side manifold of the separator and a region around the gas outlet side manifold. In such a case, the portion of the separator excluding the heat insulating member can be made of a metal material, and the heat insulating member can be made of a resin material having heat insulating properties.

  In the separator, the flow direction of the reaction gas along the first surface and the flow direction of the refrigerant along the second surface may be orthogonal to each other. In such a case, a heat insulating partition member that forms a refrigerant flow path through which the refrigerant flows on the second surface and partitions the area around the gas inlet side manifold and the area around the gas outlet side manifold in the refrigerant flow path is provided. It is preferable to provide as heat transfer suppression means.

  When such a configuration is adopted, when the flow direction of the refrigerant along the second surface is orthogonal to the flow direction of the reaction gas along the first surface, the gas inlet peripheral region of the separator (the vicinity of the gas inlet side manifold) Region) and the gas outlet peripheral region (region around the gas outlet side manifold) can be suppressed, so that the gas inlet peripheral region of the separator can be effectively heated.

  The fuel cell according to the present invention comprises an electrolyte membrane and a membrane / electrode assembly as a power generator composed of electrodes formed on both surfaces of the electrolyte membrane, and the separator.

  When such a configuration is adopted, since the separator capable of efficiently raising the temperature around the gas inlet is provided, startability in a low temperature environment is greatly improved.

  The fuel cell system according to the present invention controls the fuel cell, a refrigerant pipe communicating with the refrigerant manifold of the fuel cell, a cooling pump for supplying the refrigerant flowing through the refrigerant pipe to the fuel cell, and the cooling pump. And a control means for controlling the cooling pump so as to reduce the amount of refrigerant supplied to the fuel cell when the temperature of the refrigerant falls below a predetermined threshold value. .

  A control method for a fuel cell system according to the present invention includes the fuel cell, a refrigerant pipe communicating with a refrigerant manifold of the fuel cell, and a cooling pump that supplies the refrigerant flowing through the refrigerant pipe to the fuel cell. A control method for a fuel cell system comprising a step of controlling a cooling pump so as to reduce the amount of refrigerant supplied to the fuel cell when the temperature of the refrigerant falls below a predetermined threshold.

  When such a configuration and method are employed, the amount of refrigerant supplied to the fuel cell can be reduced when the temperature of the refrigerant falls below a predetermined threshold (for example, zero degrees Celsius, which is the freezing point of cooling water as the refrigerant). Therefore, since it is possible to suppress the supply of the refrigerant to the separator constituting the fuel cell in a low temperature environment, it is possible to efficiently raise the temperature around the gas inlet of the power generator constituting the fuel cell. As a result, the startability of the fuel cell in a low temperature environment can be greatly improved.

  According to the present invention, the temperature around the gas inlet of the fuel cell can be efficiently raised, and the starting performance of the fuel cell in a low temperature environment can be greatly improved.

  Hereinafter, a fuel cell system 1 according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the present invention is applied to an on-vehicle power generation system of a fuel cell vehicle will be described.

  First, the configuration of the fuel cell system 1 according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the fuel cell system 1 includes a fuel cell 10 that generates power by receiving supply of reaction gases (oxidizing gas and fuel gas), and a fuel gas that supplies hydrogen gas as a fuel gas to the fuel cell 10. A piping system 20, an oxidizing gas piping system 30 for supplying air as an oxidizing gas to the fuel cell 10, a refrigerant piping system 40 for supplying the refrigerant to the fuel cell 10 and cooling the fuel cell 10, and a control unit for overall control of the entire system 50 etc.

  The fuel cell 10 is formed of, for example, a solid polymer electrolyte type and has a stack structure in which a large number of single cells 10a (FIG. 2) are stacked. A unit cell 10a of the fuel cell 10 has an air electrode on one surface of an electrolyte made of an ion exchange membrane, a fuel electrode on the other surface, and a pair of air electrodes and a fuel electrode sandwiched from both sides. It has the separators 11 and 12 (FIG. 3). An oxidizing gas is supplied to the oxidizing gas flow path of one separator 11, and a fuel gas is supplied to the fuel gas flow path of the other separator 12, and the fuel cell 10 generates electric power by this gas supply. The configuration of the fuel cell 10 including the separators 11 and 12 will be described in detail later with reference to FIGS.

  The fuel gas piping system 20 includes a hydrogen supply source 21, a hydrogen supply passage 22 through which hydrogen gas supplied from the hydrogen supply source 21 to the fuel cell 10 flows, and a hydrogen supply passage through which hydrogen off-gas discharged from the fuel cell 10 is discharged. A circulation flow path 23 for returning to the confluence of 22, a hydrogen pump 24 for pumping the hydrogen off-gas in the circulation flow path 23 to the hydrogen supply flow path 22, and an exhaust / drain flow path 25 branched and connected to the circulation flow path 23. And have.

  The hydrogen supply source 21 is composed of a high-pressure tank, a hydrogen storage alloy, or the like, and is configured to be able to store, for example, 35 MPa or 70 MPa of hydrogen gas. When a shut-off valve 26 described later is opened, hydrogen gas flows out from the hydrogen supply source 21 into the hydrogen supply flow path 22. The hydrogen gas is finally depressurized to about 200 kPa, for example, by a regulator 27 described later, and supplied to the fuel cell 10. The hydrogen supply source 21 is composed of a reformer that generates a hydrogen-rich reformed gas from a hydrocarbon-based fuel and a high-pressure gas tank that stores the reformed gas generated by the reformer in a high-pressure state. May be.

  The hydrogen supply flow path 22 is provided with a shutoff valve 26 that shuts off or allows the supply of hydrogen gas from the hydrogen supply source 21 and a regulator 27 that adjusts the pressure of the hydrogen gas. The regulator 27 is a device that regulates the upstream pressure (primary pressure) to a preset secondary pressure. In this embodiment, a mechanical pressure reducing valve that reduces the primary pressure is employed as the regulator 27.

  An exhaust / drain channel 25 is connected to the circulation channel 23 via a gas / liquid separator 28 and an exhaust / drain valve 29. The gas-liquid separator 28 collects moisture from the hydrogen off gas. The exhaust / drain valve 29 operates according to a command from the control unit 50 to discharge (purge) moisture collected by the gas-liquid separator 28 and hydrogen off-gas containing impurities in the circulation passage 23 to the outside. Is. By opening the exhaust / drain valve 29, the concentration of impurities in the hydrogen off-gas in the circulation channel 23 decreases, and the hydrogen concentration in the hydrogen off-gas supplied in circulation increases. The hydrogen off-gas discharged through the exhaust / drain valve 29 and the exhaust / drain passage 25 is diluted by a diluter (not shown) and merges with the oxidizing off-gas in the exhaust passage 32. The hydrogen pump 24 circulates and supplies hydrogen gas in the circulation system to the fuel cell 10 by driving a motor (not shown).

  The oxidizing gas piping system 30 has an air supply passage 31 through which oxidizing gas supplied to the fuel cell 10 flows, and an exhaust passage 32 through which oxidizing off-gas discharged from the fuel cell 10 flows. The air supply flow path 31 is provided with a compressor 34 that takes in the oxidizing gas via the filter 33 and a humidifier 35 that humidifies the oxidizing gas fed by the compressor 34. Oxidized off-gas flowing through the exhaust passage 32 passes through the back pressure regulating valve 36 and is subjected to moisture exchange in the humidifier 35, and is finally exhausted into the atmosphere outside the system as exhaust gas. The compressor 34 takes in oxidizing gas in the atmosphere by driving a motor (not shown).

  The refrigerant piping system 40 includes a refrigerant piping 41 that communicates with a cooling flow path in the fuel cell 10, a cooling pump 42 provided in the refrigerant piping 41, a radiator 43 that cools the refrigerant discharged from the fuel cell 10, and a refrigerant. And a temperature sensor 44 that detects the temperature of the refrigerant flowing in the pipe 41. The cooling pump 42 supplies the fuel cell 10 with the refrigerant flowing through the refrigerant flow path 41 by driving a motor (not shown) controlled by the control unit 50.

  The control unit 50 detects an operation amount of an acceleration operation member (accelerator or the like) provided in the vehicle, and controls an acceleration request value (for example, a required power generation amount from a load device such as a traction motor not shown). Receives information and controls the operation of various devices in the system. In addition to the traction motor, the load device is an auxiliary device required for operating the fuel cell 10 (for example, each motor of the compressor 14, the hydrogen pump 24, the cooling pump 42, etc.), and is involved in traveling of the vehicle. It is a collective term for power consumption devices including actuators used in various devices (transmissions, wheel control units, steering devices, suspension devices, etc.), air conditioning devices (air conditioners) for passenger spaces, lighting, audio, and the like.

  The control unit 50 is configured by a computer system (not shown). Such a computer system includes a CPU, a ROM, a RAM, an HDD, an input / output interface, a display, and the like. When the CPU reads various control programs recorded in the ROM and executes desired calculations, various processes are performed. And do control.

  Specifically, the control unit 50 uses a cooling pump to reduce the amount of refrigerant supplied to the fuel cell 10 when the temperature of the refrigerant detected by the temperature sensor 44 of the refrigerant piping system 40 falls below a predetermined threshold. 42 is controlled. That is, the control unit 50 functions as control means in the present invention. The threshold value of the refrigerant temperature, which is a criterion for starting the refrigerant reduction control, can be set as appropriate according to the type of refrigerant, the specification / scale of the fuel cell 10, and the like. For example, when cooling water is employed as the refrigerant, zero degrees Celsius, which is the freezing point of the cooling water, can be employed as this threshold value.

  Next, the configuration of the fuel cell 10 according to the present embodiment will be described with reference to FIGS.

  As shown in FIG. 2, the fuel cell 10 includes a stack body 2 in which a plurality of unit cells 10 a are stacked. A current collector plate with output terminals is provided outside the unit cells 10 a located at both ends of the stack body 2. 3, the insulating plate 4 and the end plate 5 are arranged in this order. A fastening plate (not shown) is bridged between the both end plates 5, and the fastening plates are bolted to the end plates 5 so that a predetermined compressive force is applied in the stacking direction of the unit cells 10 a. It has become.

  As shown in FIG. 3, the unit cell 10 a includes an electrolyte membrane 6, an electrode catalyst layer 7 provided on both surfaces of the electrolyte membrane 6, a diffusion layer 8 disposed outside the catalyst layer 7, a reaction gas flow path. A pair of separators 11 and 12 provided with a seal, and a sealing member (not shown) that seals between the diffusion layer 8 and the separators 11 and 12 and electrically prevents a short circuit between the anode and cathode of the unit cell. Has been. The electrolyte membrane 6, the catalyst layer 7, and the diffusion layer 8 constitute a membrane / electrode assembly (MEA) 9. The MEA 9 functions as a power generator in the present invention.

  The electrolyte membrane 6 is composed of an ion exchange membrane made of a solid polymer material, and mainly has a function of moving hydrogen ions supplied from a fuel gas such as hydrogen gas from the anode electrode to the cathode electrode.

The catalyst layer 7 is disposed adjacent to the electrolyte membrane 6 and includes, for example, a solid electrolyte, carbon particles, and a catalyst supported on the carbon particles. The catalyst layer 7 and the diffusion layer 8 described later constitute an anode electrode and a cathode electrode. As the catalyst, for example, platinum or a platinum alloy is preferably used. When hydrogen (H ₂ ) supplied from the fuel gas reaches the catalyst layer 7, it dissociates into two hydrogen atoms (hydrogen active species: H ^* ) that are active on the surface of the catalyst. Furthermore, an oxidation reaction proceeds on the catalyst surface, and hydrogen ions (H ⁺ ) and electrons (e ⁻ ) are generated from the hydrogen active species. Among these, hydrogen ions are transferred into the electrolyte membrane 6. In the catalyst layer 7, by appropriately setting the blending ratio of the catalyst and the solid electrolyte, it is possible to improve the battery performance while suppressing a decrease in the catalyst utilization efficiency. Both the electrolyte membrane 6 and the catalyst layer 7 have a rectangular shape in plan view.

  The diffusion layer 8 is made of a porous material such as carbon cloth or carbon paper, and has a function of allowing fluid (product water and reaction gas) to pass therethrough and a function of electrically connecting the catalyst layer 7 and the separators 11 and 12. It is a conductor, and diffuses the reaction gas supplied from the outside of the fuel cell 10 to the catalyst layer 7 via the separators 11 and 12 and moves it to the catalyst layer 7 side. Similar to the electrolyte membrane 6 and the catalyst layer 7, the diffusion layer 8 has a rectangular shape in plan view.

  The separators 11 and 12 are boundaries that separate the stacked unit cells 10a, and a fuel gas that is supplied to the anode electrode between adjacent unit cells 10a, an oxidizing gas that is supplied to the cathode electrode, and a unit cell. And a function of preventing the refrigerant flowing between 10a from contacting each other and a function of electrically connecting adjacent unit cells 10a. One separator 11 is disposed adjacent to the diffusion layer 8 via a seal member (not shown), and an oxidizing gas such as air is applied to a surface (hereinafter referred to as “first surface”) 11 a on the diffusion layer 8 side. An oxidizing gas channel 11b to be circulated is formed. In addition, a coolant channel 11d for circulating cooling water as a coolant is formed on the surface (hereinafter referred to as “second surface”) 11c of the separator 11 opposite to the diffusion layer 8. The other separator 12 is disposed adjacent to the diffusion layer 8 via a seal member (not shown), and a surface of the diffusion layer 8 (hereinafter referred to as “first surface”) 12a has a fuel gas such as hydrogen gas. A fuel gas passage 12b for circulating the gas is formed. In addition, a refrigerant flow path 12d through which a refrigerant (for example, cooling water) flows is formed on a surface (hereinafter referred to as a “second surface”) 12c on the side opposite to the diffusion layer 8 of the separator 12.

  As shown in FIG. 3, a plurality of manifolds serving as inlets and outlets for the reaction gas and the refrigerant penetrate through the first surfaces 11a and 12a to the second surfaces 11c and 12c at the peripheral portions of the separators 11 and 12, respectively. Is provided. In the present embodiment, as shown in FIG. 3, the oxidizing gas inlet side manifold 13, the fuel gas inlet side manifold 14, the oxidizing gas outlet side manifold 15, the fuel gas outlet side manifold 16, the refrigerant inlet side manifold 17, and the refrigerant outlet side. A manifold 18 is provided. The oxidant gas inlet side manifold 13 and the oxidant gas outlet side manifold 15 communicate with the oxidant gas flow path 11b provided in one separator 11, and the fuel gas inlet side manifold 14 and the fuel gas outlet side manifold 16 are connected to the other separator. 12 communicates with a fuel gas flow path 12b provided in the fuel gas flow path 12b. Further, the refrigerant inlet side manifold 17 and the refrigerant outlet side manifold 18 communicate with the refrigerant flow paths 11 d and 12 d of both separators 11 and 12.

  The oxidizing gas inlet side manifold 13 and the fuel gas inlet side manifold 14 are for introducing the oxidizing gas and the fuel gas from the outside into the oxidizing gas channel 11b and the fuel gas channel 12b, respectively. The fuel gas outlet side manifold 16 is for discharging the oxidizing gas and the fuel gas to the outside from the oxidizing gas channel 11b and the fuel gas channel 12b, respectively. The oxidizing gas supplied from the outside of the unit cell 10a via the oxidizing gas inlet side manifold 13 flows in the oxidizing gas flow path 11b provided in one separator 11 to be cathode electrodes (diffusion layer 8 and catalyst layer 7). ) And used for power generation, and then discharged to the outside of the unit cell 10 a via the oxidizing gas outlet side manifold 15. On the other hand, the fuel gas supplied from the outside of the unit cell 10a via the fuel gas inlet side manifold 14 flows in the fuel gas flow path 12b of the other separator 12, and the anode electrode (diffusion layer 8 and catalyst layer 7). After being used for power generation, it is discharged to the outside of the unit cell 10 a via the fuel gas outlet side manifold 16.

  The refrigerant inlet side manifold 17 is for introducing a refrigerant (for example, cooling water) from the outside into the refrigerant flow paths 11d and 12d, and the refrigerant outlet side manifold 18 discharges the refrigerant from the refrigerant flow paths 11d and 12d to the outside. Is to do. The refrigerant supplied from the outside of the unit cell 10a via the refrigerant inlet side manifold 17 flows through the refrigerant flow paths 11d and 12d of both separators 11 and 12 and is used for cooling the MEA 9, and then the refrigerant outlet side. It will be discharged to the outside of the unit cell 10a via the manifold 18.

  In this embodiment, as shown in FIGS. 3 and 4, a plurality of oxidant gas inlet side manifolds 13 are formed along one side (one long side) of the separator 11, and the oxidant gas flow path 11 b is sandwiched between these sides. A plurality of oxidizing gas outlet side manifolds 15 are formed along the opposite sides (the other long side). Further, the refrigerant inlet side manifold 17 and the refrigerant outlet side manifold 18 are formed to extend along two short sides perpendicular to the long side of the separator 11. For this reason, as shown in FIG. 4, the flow direction of the oxidizing gas along the first surface 11 a of the separator 11 and the flow direction of the refrigerant along the second surface 11 d of the separator 11 are orthogonal to each other. It has become.

  The separators 11 and 12 are preferably configured so as to have high electron conductivity, excellent corrosion resistance, and the property of not releasing metal ions in a gas atmosphere. In this embodiment, the part except the heat insulation member 19 mentioned later of the separator 11 which has the oxidizing gas flow path 11b is comprised with metal materials, such as stainless steel and copper. The separator 12 having the fuel gas flow path 12b is made of a metal material such as stainless steel or copper.

As shown in FIG. 4, a portion of the separator 11 around the oxidizing gas inlet side manifold 13 (hereinafter referred to as “oxidizing gas inlet peripheral region”) A _IN and a portion around the oxidizing gas outlet side manifold 15 (hereinafter referred to as “oxidizing gas”). and a peripheral region "hereinafter) a _OUT outlet, between the heat insulating member 19 is disposed as suppressing heat transfer suppressing means heat transfer in both regions from each other. As shown in FIGS. 4 and 5, the heat insulating member 19 is a strip-shaped member having a predetermined width W and a predetermined thickness T arranged so as to extend in a direction orthogonal to the flowing direction of the oxidizing gas (the flowing direction of the refrigerant). It is a member and is comprised with the resin material which has heat insulation.

  The width W and thickness T of the heat insulating member 19 can be set as appropriate according to the surface area and thickness of the separator 11, the type of metal material constituting the separator 11, the type of resin material constituting the heat insulating member 19, and the like. . In the present embodiment, as shown in FIG. 5, the thickness T of the heat insulating member 19 is set to the same value as the dimension from the bottom surface of the oxidizing gas channel 11b of the separator 11 to the bottom surface of the refrigerant channel 11d. Yes. For this reason, the bottom surfaces of the oxidizing gas channel 11b and the refrigerant channel 11d are flush with each other without forming a step due to the heat insulating member 19, and the flow of the oxidizing gas in the oxidizing gas channel 11b and the refrigerant channel Both the circulation of the refrigerant in 11d are prevented from being hindered.

In this embodiment, the oxidizing gas inlet peripheral area _AIN is a half area on the oxidizing gas inlet side manifold 13 side of the entire oxidizing gas flow path 11b of the separator 11 and the entire area of the refrigerant flow path 11b. Among these, a portion having a predetermined thickness including both the half region on the side of the oxidizing gas inlet side manifold 13 is meant. Further, in this embodiment, the oxidizing gas outlet peripheral area A _OUT is a half area on the oxidizing gas outlet side manifold 15 side of the entire oxidizing gas flow path 11b of the separator 11 and the entire area of the refrigerant flow path 11b. Of these, a portion having a predetermined thickness including both the half region on the side of the oxidant gas outlet side manifold 15 is meant.

  Next, a control method at the time of low temperature start of the fuel cell system 1 according to the present embodiment will be described using the flowchart of FIG.

  During normal operation of the fuel cell system 1, hydrogen gas is supplied from the hydrogen supply source 21 to the fuel electrode of the fuel cell 10 through the hydrogen supply channel 22, and the air that has been humidified is supplied to the air supply channel 31. Is supplied to the oxidation electrode of the fuel cell 10 through the electric power to generate electricity. At this time, the power (required power) to be drawn from the fuel cell 10 is calculated by the control unit 50, and hydrogen gas and air in amounts corresponding to the amount of power generation are supplied into the fuel cell 10. In the present embodiment, specific start control is performed in such a low temperature environment before the normal operation.

  First, the control unit 50 of the fuel cell system 1 detects the refrigerant temperature using the temperature sensor 44 of the refrigerant piping system 40 when detecting the ON signal (system start request) of the ignition switch in the operation stop state. Then, it is determined whether or not the refrigerant temperature is lower than a predetermined threshold (for example, zero degrees Celsius) (refrigerant temperature determination step: S1).

  Next, when it is determined in the refrigerant temperature determination step S1 that the refrigerant temperature is equal to or higher than the predetermined threshold, the control unit 50 proceeds to a step of performing normal operation (normal operation control step S6 described later). On the other hand, when it is determined in the refrigerant temperature determination step S1 that the refrigerant temperature is lower than the predetermined threshold, the control unit 50 reduces the supply amount of the refrigerant to the fuel cell 10 from the supply amount during normal operation (or The cooling pump 42 is controlled so as to stop the supply of the refrigerant (refrigerant supply amount reduction step: S2).

  Following the refrigerant supply amount reduction step S2, the control unit 50 performs a low-efficiency operation aimed at rapid warm-up (below-freezing operation control step: S3). Then, the control unit 50 estimates the temperature of the fuel cell 10 based on the duration of the low-efficiency operation and determines whether or not this estimated temperature has reached a predetermined temperature (fuel cell temperature determination step: S4). When a negative determination is obtained, the sub-freezing operation control step S3 is repeatedly performed. On the other hand, when a positive determination is obtained in the fuel cell temperature determination step S4, the control unit 50 increases the amount of refrigerant supplied to the fuel cell 10 and returns it to the amount supplied during normal operation (refrigerant supply amount). Increase process: S5), and then normal operation is performed (normal operation control process: S6).

In the separator 11 constituting the fuel cell 10 of the fuel cell system 1 according to the embodiment described above, heat transfer between the oxidizing gas inlet peripheral area _AIN and the oxidizing gas outlet peripheral area _AOUT can be suppressed. Therefore, diffusion of heat generated in the oxidizing gas inlet peripheral area _AIN can be suppressed. Accordingly, it is possible to effectively increase the temperature of the oxidizing gas inlet peripheral region A _IN of the separator 11, it is possible to efficiently raise the temperature of the oxidizing gas inlet peripheral region of the MEA which are located close to the separator 11. As a result, the startability of the fuel cell 10 in a low temperature environment can be greatly improved.

  Further, in the fuel cell system 1 according to the embodiment described above, the supply amount of the refrigerant to the fuel cell 10 can be reduced when the temperature of the refrigerant falls below a predetermined threshold. Accordingly, since it is possible to suppress the supply of the refrigerant to the separators 11 and 12 constituting the fuel cell 10 in a low temperature environment, the temperature of the area around the oxidizing gas inlet of the MEA 9 constituting the fuel cell 10 is efficiently raised. Can be made. As a result, the startability of the fuel cell 10 in a low temperature environment can be greatly improved.

In the above embodiment, an example (FIG. 5) in which the heat insulating member 19 is not raised from the bottom surface of the refrigerant flow path 11d is shown, but the configuration of the heat insulating member is not limited thereto. For example, as shown in FIG. 7, a heat insulating member 19 </ b> A configured to protrude from the bottom surface of the refrigerant channel 11 d to the opening side of the refrigerant channel 11 d can be employed. When such a heat insulating member 19A is employed, the entire region of the refrigerant flow path 11d is partitioned into a half region on the oxidizing gas inlet side manifold 13 side and a half region on the oxidizing gas outlet side manifold 15 side. Thus, the circulation of the refrigerant between these regions is interrupted. As a result, the oxidizing gas inlet peripheral region thermal diffusion generated by A _IN separator 11 can be further suppressed, the oxidizing gas inlet peripheral region A _IN can be more effectively heated. In such a case, the heat insulating member 19A functions as a partition member in the present invention.

Moreover, in the above embodiment, although the example which applied this invention to the separator 11 which has arrange | positioned the manifold so that the distribution direction of oxidizing gas and the distribution direction of a refrigerant | coolant were orthogonally shown, as shown in FIG. The present invention can also be applied to the separator 11A in which the manifold is arranged so that the flow direction of the oxidizing gas and the flow direction of the refrigerant are parallel to each other. In the separator 11A, the oxidizing gas inlet side manifold 13A and the refrigerant inlet side manifold 17A are formed adjacent to each other along one side (one long side), and the oxidizing gas channel 11b and the refrigerant channel 11d are sandwiched between these sides. An oxidizing gas outlet side manifold 15A and a refrigerant outlet side manifold 18A are formed adjacent to each other along the opposite side (the other long side). Also in the separator 11A, the heat transfer between the two regions can be suppressed by disposing the heat insulating member 19 between the oxidizing gas inlet peripheral region _AIN and the oxidizing gas outlet peripheral region _AOUT .

  Further, in the above embodiment, the example in which the present invention is applied to the cathode-side separator 11 having the oxidizing gas channel 11b has been shown, but the present invention is also applied to the anode-side separator 12 having the fuel gas channel 12b. Can be applied. Also in the separator 12 on the anode side, the heat transfer between the two regions can be suppressed by arranging the heat transfer suppressing means such as a heat insulating member between the fuel gas inlet peripheral region and the fuel gas outlet peripheral region.

  In the embodiment described above, the oxidizing gas flow path 11b is formed on the surface (first surface 11a) that is disposed close to the MEA 9, while the surface (second surface 11c) that is disposed on the opposite side of the MEA 9. Although the example in which the present invention is applied to the separator 11 in which the refrigerant flow path 11d is formed is shown in FIG. 1, the present invention can be applied to a flat separator in which the oxidizing gas flow path and the refrigerant flow path are not formed on the surface. Can do. Even in a flat separator, the heat transfer between the two regions can be suppressed by disposing a heat transfer suppressing means such as a heat insulating member between the oxidizing gas inlet peripheral region and the oxidizing gas outlet peripheral region.

  Moreover, although the example which reduced the refrigerant | coolant supply amount when the refrigerant | coolant temperature was less than a predetermined threshold value was shown in the above embodiment, the criterion of refrigerant | coolant reduction control start is not limited to this. For example, when the amount of water expected to be generated in the fuel cell 10 before the freezing point breakthrough (expected amount of generated water) exceeds a predetermined allowable generation amount, the refrigerant supply amount can be reduced.

  In the above embodiment, the example in which the supply amount of the refrigerant to the fuel cell 10 is increased when the estimated temperature of the fuel cell 10 reaches the predetermined temperature has been described. Is not limited to this. For example, when the output of the fuel cell 10 reaches a predetermined value, the amount of refrigerant supplied to the fuel cell 10 can be increased.

  Further, in each of the above embodiments, an example in which the fuel cell system according to the present invention is mounted on a fuel cell vehicle has been shown. Such a fuel cell system can also be mounted. Further, the fuel cell system according to the present invention may be applied to a stationary power generation system used as a power generation facility for a building (house, building, etc.).

1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a perspective view of the fuel cell of the fuel cell system shown in FIG. It is a disassembled perspective view of the single cell which comprises the fuel cell shown in FIG. It is a top view of the cathode side separator which comprises the single battery shown in FIG. It is sectional drawing in the VV part of the separator shown in FIG. FIG. 2 is a flowchart for explaining a control method at a low temperature start of the fuel cell system shown in FIG. 1. FIG. It is sectional drawing which shows the modification of a separator. It is a top view which shows the other modification of a separator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 6 ... Electrolyte membrane, 7 ... Catalyst layer (electrode), 8 ... Diffusion layer (electrode), 9 ... MEA (electric power generation body, membrane electrode assembly), 10 ... Fuel cell, 11 / 11A ... Separator, 11a ... 1st surface, 11c ... 2nd surface, 11d ... Refrigerant flow path, 13 * 13A ... oxidizing gas inlet side manifold, 15 * 15A ... oxidizing gas outlet side manifold, 17 * 17A ... refrigerant inlet side manifold , 18, 18A ... refrigerant outlet side manifold, 19 ... heat insulating member (heat transfer suppressing means), 19A ... heat insulating member (heat transfer suppressing means, partition member), 41 ... refrigerant pipe, 42 ... cooling pump, 50 ... control unit ( Control means), A _IN ... oxidizing gas inlet peripheral area, A _OUT ... oxidizing gas outlet peripheral area.

Claims (8)

A first surface disposed close to the power generator of the fuel cell; a gas inlet side manifold for supplying a reaction gas from the outside to the first surface; and a reaction gas discharged from the first surface to the outside. A gas outlet side manifold, a second surface disposed on the opposite side of the power generation body, a refrigerant inlet side manifold for supplying a refrigerant to the second surface from the outside, and the second surface A refrigerant outlet side manifold for discharging the refrigerant to the outside, and the reaction gas supplied from the outside circulates along the first surface, while the refrigerant supplied from the outside flows to the second surface A separator for a fuel cell configured to be distributed along
Comprising a heat transfer suppressing means for suppressing heat transfer between a region around the gas inlet side manifold and a region around the gas outlet side manifold;
Separator. The reaction gas is air as an oxidizing gas.
The separator according to claim 1. The heat transfer suppression means is a heat insulating member arranged between a region around the gas inlet side manifold and a region around the gas outlet side manifold.
The separator according to claim 1 or 2. The separator is composed of a metal material except for the heat insulating member,
The heat insulating member is composed of a resin material having heat insulating properties,
The separator according to claim 3. The flow direction of the reactive gas along the first surface and the flow direction of the refrigerant along the second surface are configured to be orthogonal to each other, and the refrigerant flows through the second surface. A refrigerant flow path is formed,
The heat transfer suppression means has a heat insulating partition member that partitions a region around the gas inlet side manifold and a region around the gas outlet side manifold in the refrigerant flow path.
The separator according to any one of claims 1 to 4. A membrane / electrode assembly as a power generator composed of an electrolyte membrane and electrodes formed on both sides of the electrolyte membrane;
A separator according to any one of claims 1 to 5;
A fuel cell comprising: 7. The fuel cell according to claim 6, a refrigerant pipe communicating with a refrigerant manifold of the fuel cell, a cooling pump for supplying refrigerant flowing through the refrigerant pipe to the fuel cell, and a control means for controlling the cooling pump. A fuel cell system comprising:
The control means controls the cooling pump so as to reduce the amount of refrigerant supplied to the fuel cell when the temperature of the refrigerant falls below a predetermined threshold.
Fuel cell system. A control method for a fuel cell system, comprising: the fuel cell according to claim 6; a refrigerant pipe communicating with a refrigerant manifold of the fuel cell; and a cooling pump that supplies the refrigerant flowing through the refrigerant pipe to the fuel cell. Because
A step of controlling the cooling pump so as to reduce the amount of refrigerant supplied to the fuel cell when the temperature of the refrigerant falls below a predetermined threshold;
Control method of fuel cell system.

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