JP2006032136A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system restrained from lowering of power generating efficiency caused by the water accumulated in a gas diffusion layer generated when a required output value is sharply lowered. <P>SOLUTION: The fuel cell system comprises a fuel cell 10, a required output value acquiring means 40 acquiring a required output value to the fuel cell 10, oxidant supply quantity adjusting means 21, 40 adjusting the quantity of oxidant gas to be supplied to the fuel cell 10, fuel supply quantity adjusting means 24, 25, 40 adjusting the quantity of fuel gas to be supplied to the fuel cell 10, and cooling amount adjusting means 31, 33, 40 adjusting the cooling amount of the fuel cell 10 cooled by cooling means 30 to 33. In the case that the required output value is sharply lowered, the cooling amount adjusting means 31, 33, 40 lowers the cooling amount of the fuel cell 10 in compliance with the required output value. In the case that the required output value is sharply lowered, the oxidant supply quantity adjusting means 21, 40 or the fuel supply quantity adjusting means 24, 25, 40 delay the lowering of the supply quantity of oxidant gas or fuel gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system including a fuel cell that generates electric energy by a chemical reaction between hydrogen and oxygen, and is particularly suitable for a vehicle fuel cell system in which required power generation output is frequently changed.

  For example, in a fuel cell system mounted on an electric vehicle, it is necessary to change the generated power of the fuel cell according to the traveling pattern of the vehicle. Specifically, the control unit of the fuel cell system calculates the amount of hydrogen and oxygen necessary to generate the required output value for running the vehicle, and the gas flow rate supplied to the fuel cell becomes the required flow rate. Thus, a command is output to the hydrogen supply device and the air supply device, and the gas flow rate control is performed.

  The fuel cell system is provided with a cooling system using cooling water or the like to cool the fuel cell. Since the amount of heat generated by the fuel cell changes with the change in output, the amount of cooling of the fuel cell by the cooling system needs to be changed with the change in output of the fuel cell.

  However, in the configuration in which the parameters such as the hydrogen supply amount, air supply amount, and cooling amount are changed in synchronization with the power demand amount, the output demand amount suddenly decreases immediately after the climbing up or immediately after the rapid acceleration. Flooding in which water generated on the air electrode side of the fuel cell during power generation stays in a gas diffusion layer of an MEA (Membrane Electrode Assembly) occurs. Water generated on the air electrode side permeates the electrolyte membrane and stays in the gas diffusion layer on the hydrogen electrode side. As a result, the gas diffusion layer is covered with water, the reaction gas is prevented from diffusing, and the power generation efficiency of the fuel cell is reduced.

  In view of the above points, an object of the present invention is to suppress a reduction in power generation efficiency of a fuel cell due to moisture remaining in a gas diffusion layer when a required output value to the fuel cell is rapidly reduced.

In order to achieve the above object, in the first aspect of the present invention, the fuel cell (10) that generates electric energy by the electrochemical reaction between the oxidant gas and the fuel gas, and the output required value for the fuel cell (10) are set. Output request value acquisition means (40) to be acquired, oxidant supply amount adjustment means (21, 40) for adjusting the supply amount of oxidant gas to the fuel cell (10) based on the output request value, output request value The fuel supply amount adjusting means (24, 25, 40) for adjusting the supply amount of the fuel gas to the fuel cell (10) based on the above, and the cooling means (30) for cooling the fuel cell (10) based on the required output value To 33) cooling amount adjusting means (31, 33, 40) for adjusting the cooling amount,
The cooling amount adjusting means (31, 33, 40) reduces the cooling amount of the fuel cell (10) corresponding to the output request value at a predetermined time when the decrease rate of the output request value at the predetermined time exceeds a predetermined value. The oxidant supply amount adjusting means (21, 40) and the fuel supply amount adjusting means (24, 25, 40) supply the oxidant gas when the reduction rate of the required output value at a predetermined time exceeds a predetermined value. It is characterized in that both the amount and the supply amount of the fuel gas are reduced corresponding to the output request value after a predetermined time has elapsed from a predetermined time point.

  As described above, after the output required value of the fuel cell (10) rapidly decreases, the supply amount of the fuel gas and the supply amount of the oxidant gas are supplied in an excessive supply amount for a predetermined time. Water accumulated in the fuel cell (10) can be pushed out by the gas flow of the oxidant gas. Thereby, it is possible to suppress moisture from being retained in the gas diffusion layer, and it is possible to suppress a decrease in the power generation efficiency of the fuel cell (10) when the required output value of the fuel cell (10) is rapidly reduced. It becomes.

  Further, the fuel gas and the oxidant gas are excessively supplied with respect to the required output value for a predetermined time. By maintaining the power generation amount without decreasing during this predetermined time, the fuel cell (10) generates a larger amount of heat generated by the power generation than the cooling amount, and the temperature inside the fuel cell (10) temporarily rises. As a result, the saturated water vapor partial pressure inside the fuel cell (10) can be increased, and moisture evaporation inside the fuel cell (10) can be promoted.

  Further, it takes some time for the heat generated by the fuel cell due to the excessive supply of the fuel gas and the oxidant gas to be conducted into the fuel cell (10).

  Therefore, in the invention described in claim 2, the oxidant supply amount adjusting means (21, 40) reduces the supply amount of the oxidant gas corresponding to the output request value after the first predetermined time has elapsed from the predetermined time point. The fuel supply amount adjusting means (24, 25, 40) reduces the fuel gas supply amount corresponding to the output request value after a second predetermined time longer than the first predetermined time, and this first predetermined amount. It is characterized by maintaining the power generation amount without reducing it over time. As a result, fuel is supplied with an excessively supplied oxidant gas using heat accumulated in the fuel cell (10) between the first predetermined time and the second predetermined time. The oxidant electrode side passage of the battery (10) can be dried without waste.

  Further, in the invention according to claim 3, the fuel supply amount adjusting means (24, 25, 40) decreases the supply amount of the fuel gas corresponding to the output request value after the first predetermined time has elapsed from the predetermined time point. The oxidant supply amount adjusting means (21, 40) reduces the supply amount of the oxidant gas corresponding to the output request value after the elapse of the second predetermined time longer than the first predetermined time. It is characterized by maintaining the power generation amount without reducing it over time. Thus, the fuel cell is supplied with the excessively supplied fuel gas by using the heat accumulated in the fuel cell (10) between the first predetermined time and the second predetermined time. The fuel electrode side passage of (10) can be dried without waste.

  Further, in the invention according to claim 4, the cooling amount adjusting means (31, 33, 40) is configured so that when the rate of decrease in the output request value at a predetermined time exceeds a predetermined value, the fuel cell (10) at a predetermined time. The amount of cooling is decreased corresponding to the required output value, and the oxidant supply amount adjusting means (21, 40) and the fuel supply amount adjusting means (24, 25, 40) have a predetermined rate of decrease in the required output value at a predetermined time. If the value exceeds the value, either the supply amount of the oxidant gas or the supply amount of the fuel gas is reduced corresponding to the output request value at a predetermined time point, and the other is set to the output request value after a predetermined time has elapsed from the predetermined time point. It is characterized by a corresponding decrease.

  In this way, after the output request value of the fuel cell (10) suddenly decreases, either one of the fuel gas supply amount and the oxidant gas supply amount is supplied in a state where the supply amount is excessive for a predetermined time. The water staying inside the fuel cell (10) can be pushed out by the gas flow of the fuel gas or oxidant. Thereby, it is possible to suppress moisture from being retained in the gas diffusion layer, and it is possible to suppress a decrease in the power generation efficiency of the fuel cell (10) when the required output value of the fuel cell (10) is rapidly reduced. It becomes. When only the oxidant gas is supplied in a state where the supply amount is excessive for a predetermined time, the consumption amount of the fuel gas can be suppressed.

  Further, in the invention described in claim 5, the oxidant supply amount adjusting means (21, 40) and the fuel supply amount adjusting means (24, 25, 40) are such that the rate of decrease of the output request value at a predetermined point in time is a predetermined value. If it exceeds, either one of the supply amount of the oxidant gas or the supply amount of the fuel gas is decreased at a predetermined time in accordance with the required output value, and the other is increased at the predetermined time and after a predetermined time has elapsed from the predetermined time. It is characterized in that it is lowered corresponding to the output request value. As described above, when delaying the decrease in the supply amount of either the fuel gas supply amount or the oxidizing gas supply amount, the gas supply amount is temporarily increased to promote the drying of the fuel cell (10). And can be dried in a shorter time.

  In the invention according to claim 6, the cooling means (30 to 33) includes a pump (31) for circulating the heat medium in the fuel cell (10) and heat of the fuel cell (10) through the heat medium. A radiator (32) that discharges to the outside and a blower fan (33) that blows air to the radiator (32) are provided, and the cooling amount adjusting means adjusts the circulation amount of the heat medium by the pump (31), or The cooling amount of the fuel cell (10) is adjusted by performing any one of the adjustments of the blowing amount by the fan (33). Thereby, when only adjusting the circulation amount of the heat medium by the pump (31), the power consumption of the blower fan (33) can be reduced, and when only adjusting the blower amount of the blower fan (33), The power consumption of the pump (31) can be reduced.

  Further, as in the seventh aspect of the invention, when the rate of decrease in the output request value exceeds a predetermined value, the output request value after the elapse of a predetermined time set within 30 seconds from the predetermined time point The output request value can be ½ or less of the output request value.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the fuel cell system of the present invention is applied to an electric vehicle (fuel cell vehicle) that runs using a fuel cell as a power source.

  FIG. 1 shows the configuration of the fuel cell system according to the first embodiment of the present invention. As shown in FIG. 1, the fuel cell system of this embodiment includes a fuel cell 10, an air supply device 21, a hydrogen supply device 23, cooling systems 30 to 33, a control device (ECU) 40, and the like.

  The fuel cell (FC stack) 10 of the present embodiment uses a solid polymer electrolyte fuel cell, and is configured by stacking a plurality of cells serving as basic units. FIG. 2 shows the structure of the cell. As shown in FIG. 2, each cell has a configuration in which an electrolyte membrane 1 is sandwiched between a pair of electrodes 2 and 3. As the electrolyte membrane 1 and the electrodes 2 and 3, for example, a MEA (Membrane Electrode assembly) in which electrodes (hydrogen electrode 2 and oxygen electrode 3) are bonded to both surfaces of the solid polymer membrane 1 is used. The electrodes 2 and 3 are composed of a catalyst layer and a gas diffusion layer. One electrode 2 is configured as an oxygen electrode (cathode) to which oxygen is supplied, and the other electrode 3 is configured as a hydrogen electrode (anode) to which hydrogen is supplied. The electrolyte membrane 1 and the electrodes 2 and 3 are sandwiched by separators 4 and 5 that also serve as a supply path for a reactive gas such as hydrogen or oxygen, for example.

  In the fuel cell 10, when hydrogen and oxygen are supplied to the electrodes 2 and 3, the following electrochemical reaction (electromotive reaction) of hydrogen and oxygen occurs, and electric energy is generated. Hydrogen and oxygen correspond to the fuel gas and oxidant gas of the present invention, respectively, and the hydrogen electrode and oxygen electrode correspond to the fuel electrode and oxidant electrode, respectively.

Hydrogen electrode (anode) H ₂ → 2H ⁺ + 2e ⁻
Oxygen electrode (cathode) 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
Overall H ₂ + 1 / 2O ₂ → H ₂ O
The fuel cell 10 is configured to supply electric power to a traveling motor (load) 11 via an inverter (not shown). Further, the fuel cell 10 supplies electric power to electric devices such as secondary batteries and auxiliary machines (not shown).

  The fuel cell system is provided with an air path 20 for supplying air (oxygen) to the oxygen electrode side of the fuel cell 10. Air is supplied to the air path 20 from an air supply device 21. An air compressor can be used as the air supply device 21. By varying the rotation speed of the compressor 21, the air supply amount (oxygen supply amount) to the fuel cell 10 can be adjusted. The compressor 21 is configured to operate based on a control signal from the control device 40, and the compressor 21 and the control device 40 correspond to the oxidant supply amount adjusting means of the present invention.

  The fuel cell system is provided with a hydrogen path 22 for supplying hydrogen to the hydrogen electrode side of the fuel cell 10. Hydrogen is supplied to the hydrogen path 22 from the hydrogen supply device 23. As the hydrogen supply device 23, for example, a high-pressure hydrogen tank or a hydrogen tank that stores pure hydrogen by incorporating a hydrogen storage material such as a hydrogen storage alloy can be used. The hydrogen path 22 is provided with a shut valve 24 and a hydrogen regulator 25. When supplying hydrogen to the fuel cell 10, the shut valve 24 is opened, and hydrogen having a desired pressure by the hydrogen regulator 25 is supplied to the fuel cell 10. The amount of hydrogen supplied to the fuel cell 10 can be adjusted by adjusting the opening of the hydrogen regulator 25. The shut valve 24 and the hydrogen regulator 25 are configured to operate based on a control signal from the control device 40, and the shut valve 24, the hydrogen regulator 25, and the control device 40 correspond to the fuel supply amount adjusting means of the present invention. ing.

  The fuel cell 10 generates heat with power generation. In the polymer electrolyte fuel cell, it is necessary to operate at around 80 ° C. in view of the heat resistant temperature and efficiency of the membrane. For this reason, the fuel cell system is provided with cooling systems 30 to 33 for cooling the fuel cell 10.

  The cooling systems 30 to 33 include a cooling water path (heating medium path) 30 for circulating cooling water as a heat medium in the fuel cell 10, a water pump 31 for pumping the cooling water, and a radiator (heat radiator) for radiating the cooling water. 32 or the like. As the cooling water, a mixed solution of ethylene glycol and water can be used.

  By operating the water pump 31, the cooling water can be circulated through the fuel cell 10 via the cooling water path 30. The heat generated in the fuel cell 10 is discharged out of the system by the radiator 32 through the cooling water. The radiator 32 is provided with a blower fan 33. By rotating the blower fan 33, air is blown to the radiator 32, and heat can be released from the radiator 32 to the outside air. The water pump 31 and the blower fan 33 are configured to operate based on a control signal from the control device 40, and the water pump 31, the blower fan 33, and the control device 40 correspond to the cooling amount adjusting means of the present invention. Yes.

  The control device 40 performs various controls in the fuel cell system. As the control device 40, for example, a general microcomputer having a CPU, a memory (ROM, RAM) and the like can be used. The control device 40 corresponds to the required output value acquisition means of the present invention, and receives an accelerator opening signal (not shown), and calculates an output required value (required power generation amount) for the fuel cell 10 based on the accelerator opening. It is configured as follows. In addition, the control device 40 outputs an operation instruction signal (control signal) to the air supply device 21, the shut valve 24, the regulator 25, the water pump 31, the blower fan 33, and the like.

  The control device 40 adjusts the air supply amount and the hydrogen supply amount to the fuel cell 10 in response to a change in the output required value of the fuel cell 10. Specifically, the control device 40 calculates the required output value to the fuel cell 10 from the accelerator opening operated by the user, and the required air supply amount and required hydrogen supply for the fuel cell 10 to output the required output value. Calculate the quantity. The required air supply amount and the required hydrogen supply amount are gas supply amounts necessary for the fuel cell 10 to generate the required output value, and are values that can be uniquely calculated. The control device 40 adjusts the rotation speed of the air supply device 21 in accordance with the required air supply amount, adjusts the opening of the regulator 25 in accordance with the required hydrogen supply amount, and the hydrogen supply amount of the hydrogen supply device 23. Adjust the air supply. Thereby, the electric power generation amount of the fuel cell 10 can be made into an output request value.

  Further, the control device 40 controls the rotational speed of the water pump 31 and the rotational speed of the blower fan 33 in response to a change in the output request value of the fuel cell 10. Specifically, in the fuel cell 10, the heat generation amount increases as the power generation amount increases, and the heat generation amount decreases as the power generation amount decreases. Therefore, the amount of cooling of the fuel cell 10 is adjusted by adjusting at least one of the rotational speed of the water pump 31 or the rotational speed of the blower fan 33. By adjusting the rotation speed of the water pump 31, the circulation amount of the cooling water can be adjusted, and thereby the cooling amount of the fuel cell 10 can be adjusted. Further, by adjusting the rotational speed of the blower fan 33, the amount of air blown to the radiator 32 can be adjusted, whereby the amount of heat released from the radiator 32 can be adjusted, and the amount of cooling of the fuel cell 10 can be adjusted. .

  Next, flooding prevention control of the fuel cell system according to the first embodiment will be described with reference to FIG. FIG. 3 is a timing chart showing the contents of the flooding prevention control of the first embodiment.

  The control device 40 performs flooding prevention control when the required output value of the fuel cell 10 rapidly decreases, that is, when the rate of decrease in the required output value of the fuel cell 10 exceeds a predetermined value. “When the rate of decrease in the output request value exceeds a predetermined value” refers to an output after a predetermined time from the predetermined time with respect to the output request value P0 at a predetermined time for determining whether or not the output request value has rapidly decreased. This is a case where the required value P1 is 1/2 or less. The predetermined time can be set within 30 seconds.

  When it is determined that the output of the fuel cell 10 rapidly decreases at a predetermined time in FIG. 3, the control device 40 decreases the cooling amount of the fuel cell 10 in synchronization with the output request value of the fuel cell 10. The cooling amount is reduced by reducing both the water pump speed and the fan speed. At this time, the hydrogen supply amount and the air supply amount are not synchronized with the required output value of the fuel cell 10 and are not changed as they are.

  After the first predetermined time t1 has elapsed, the hydrogen supply amount is reduced to the necessary hydrogen supply amount corresponding to the required output value of the fuel cell 10. At this time, the air supply amount is not changed as it is. Then, after the elapse of the second predetermined time t2 longer than the first predetermined time t1, the air supply amount is reduced to the necessary air supply amount corresponding to the required output value of the fuel cell 10.

  In the flooding prevention control described above, after the amount of cooling of the fuel cell 10 by the cooling systems 30 to 33 is decreased in synchronization with the sudden decrease in the output required value of the fuel cell 10, the hydrogen supply amount is controlled for the first predetermined time t1. The decrease is delayed, and the decrease in the air supply amount is delayed by the second predetermined time t2.

  As described above, after the output request value of the fuel cell 10 rapidly decreases, hydrogen is supplied in an excessive amount only for the first predetermined time t1, so that the gas flow caused by the excess hydrogen causes the internal flow of the fuel cell 10 to increase. Water remaining in the hydrogen electrode side passage can be pushed out. Similarly, after the output request value of the fuel cell 10 has suddenly decreased, air is supplied in an excessive supply amount for the second predetermined time t2, so that the air inside the fuel cell 10 is generated by the gas flow due to excess air. The water staying in the pole side passage can be pushed out. As a result, it is possible to suppress the retention of moisture in the gas diffusion layer, and it is possible to suppress a decrease in the power generation efficiency of the fuel cell 10 when the required output value of the fuel cell 10 rapidly decreases.

  In addition, during the first predetermined time t1, hydrogen and air (oxygen) are excessively supplied with respect to the required output value of the fuel cell 10. By maintaining the power generation amount without decreasing during this predetermined time t1, the fuel cell 10 generates a larger amount of heat generated by power generation than the cooling amount, and the temperature inside the fuel cell 10 temporarily rises. As a result, the saturated water vapor partial pressure inside the fuel cell 10 can be increased, and moisture evaporation inside the fuel cell 10 can be promoted.

  Furthermore, a certain amount of time is required for the heat generated during the first predetermined time t1 described above to be conducted to the inside of the fuel cell 10. Therefore, as in the present embodiment, by setting the second predetermined time t2 for delaying the decrease in the air supply amount longer than the first predetermined time t1 for delaying the decrease in the hydrogen supply amount, the time between t2 and t1 is increased. The heat accumulated in the fuel cell 10 can be used to dry the air electrode side passage of the fuel cell 10 with excess air without waste.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in the content of the flooding prevention control. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  FIG. 4 is a timing chart showing details of the flooding prevention control of the second embodiment. As shown in FIG. 4, when it is determined that the output of the fuel cell 10 rapidly decreases, the control device 40 decreases the cooling amount of the fuel cell 10 in synchronization with the output request value of the fuel cell 10. At this time, the hydrogen supply amount and the air supply amount are not synchronized with the required output value of the fuel cell 10 and are not changed as they are.

  After the first predetermined time t1 has elapsed, the air supply amount is reduced to the required air supply amount corresponding to the required output value of the fuel cell 10. At this time, the air supply amount is not changed as it is. Then, after the elapse of the second predetermined time t2 longer than the first predetermined time t1, the hydrogen supply amount is reduced to the necessary hydrogen supply amount corresponding to the required output value of the fuel cell 10.

  Also in the configuration of the second embodiment, after the output required value of the fuel cell 10 suddenly decreases, hydrogen is supplied in an excessive supply amount for the second predetermined time t2, and only for the first predetermined time t1. By supplying air in a state where the supply amount is excessive, the water remaining in the fuel cell 10 can be pushed out by the gas flow of excess hydrogen and air. As a result, it is possible to suppress the retention of moisture in the gas diffusion layer, and it is possible to suppress a decrease in the power generation efficiency of the fuel cell 10 when the required output value of the fuel cell 10 rapidly decreases.

  Further, during the first predetermined time t1, hydrogen and air (oxygen) are excessively supplied with respect to the required output value of the fuel cell 10, so that the temperature inside the fuel cell 10 rises temporarily, thereby It is possible to increase the saturated water vapor partial pressure inside the fuel cell 10 and promote moisture evaporation inside the fuel cell 10. Further, as in the second embodiment, by setting the second predetermined time t2 for delaying the decrease in the hydrogen supply amount longer than the first predetermined time t1 for delaying the decrease in the air supply amount, By utilizing the heat accumulated in the fuel cell 10 in the meantime, the hydrogen electrode side passage of the fuel cell 10 can be dried without waste with excessively supplied hydrogen.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the first embodiment in the details of the flooding prevention control. The same parts as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 5 is a timing chart showing the contents of the flooding prevention control of the third embodiment. As shown in FIG. 5, the control device 40 decreases the cooling amount of the fuel cell 10 in synchronization with the output request value of the fuel cell 10 when it is determined that the output of the fuel cell 10 rapidly decreases. At this time, the hydrogen supply amount, the air supply amount, and the power generation amount are not synchronized with the required output value of the fuel cell 10 and are not changed as they are. Then, the air supply amount, the hydrogen supply amount, and the power generation amount are reduced to the required air supply amount corresponding to the required output value of the fuel cell 10 after the predetermined time t1 has elapsed.

  Even in the configuration of the third embodiment, after the output required value of the fuel cell 10 suddenly decreases, hydrogen and air are supplied in an excessive supply amount for a predetermined time t1, so that excess hydrogen and air are used. Water accumulated in the fuel cell 10 can be pushed out by the gas flow. As a result, it is possible to suppress the retention of moisture in the gas diffusion layer, and it is possible to suppress a decrease in the power generation efficiency of the fuel cell 10 when the required output value of the fuel cell 10 rapidly decreases.

  In addition, hydrogen and air (oxygen) are excessively supplied with respect to the required output value of the fuel cell 10 for a predetermined time t1, and further, the power generation amount is maintained without decreasing for the predetermined time t1, so that the cooling amount Therefore, the temperature inside the fuel cell 10 temporarily rises, thereby increasing the saturated water vapor partial pressure inside the fuel cell 10 and promoting the evaporation of water inside the fuel cell 10. Further, as in the third embodiment, the reduction of the air supply amount and the hydrogen supply amount is delayed by the same predetermined time t1, so that the hydrogen supplied excessively using the heat accumulated in the fuel cell 10 is used. Thus, the hydrogen electrode side passage and the air electrode side passage of the fuel cell 10 can be dried without waste.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is different from the first embodiment in the content of flooding prevention control. The same parts as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 6 is a timing chart showing the contents of the flooding prevention control of the fourth embodiment. As shown in FIG. 6, the control device 40 decreases the cooling amount of the fuel cell 10 in synchronization with the output request value of the fuel cell 10 when it is determined that the output of the fuel cell 10 rapidly decreases. Further, the hydrogen supply amount is decreased in synchronization with the output required value of the fuel cell 10. At this time, the air supply amount is not synchronized with the required output value of the fuel cell 10 and is not changed as it is. Then, the air supply amount is reduced to the required air supply amount corresponding to the required output value of the fuel cell 10 after the elapse of the predetermined time t1.

  In the configuration of the fourth embodiment, after the required output value of the fuel cell 10 has suddenly decreased, air is supplied in an excessive supply amount for a predetermined time t1, so that the fuel cell can be generated with a gas flow caused by excess air. The water staying in the air electrode side passage inside 10 can be pushed out. As a result, it is possible to suppress the retention of moisture in the gas diffusion layer, and it is possible to suppress a decrease in the power generation efficiency of the fuel cell 10 when the required output value of the fuel cell 10 rapidly decreases. In the fourth embodiment, since the decrease in the hydrogen supply amount is not delayed, the hydrogen consumption can be suppressed.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIG. The fifth embodiment is different from the fourth embodiment in that the air supply amount is increased before the required air supply amount corresponding to the required output value of the fuel cell 10 is decreased. The same parts as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 7 is a timing chart showing the contents of the flooding prevention control of the fifth embodiment. In the fifth embodiment, as shown in FIG. 7, the control device 40 cools the fuel cell 10 in synchronization with the output request value of the fuel cell 10 when it is determined that the output of the fuel cell 10 suddenly decreases. Reduce the amount. Further, the hydrogen supply amount is decreased in synchronization with the output required value of the fuel cell 10. At this time, the air supply amount is not synchronized with the required output value of the fuel cell 10 but is increased by a predetermined amount. Then, the air supply amount increased after the lapse of the predetermined time t1 is reduced to the necessary air supply amount corresponding to the output required value of the fuel cell 10.

  Also in the configuration of the fifth embodiment, the same effects as those of the fourth embodiment can be obtained. Further, by increasing the air supply amount for a predetermined time t1 as in the fifth embodiment, drying of the air electrode side passage of the fuel cell 10 can be promoted and drying can be performed in a shorter time.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIG. The sixth embodiment is different from the fourth embodiment in that only the decrease in the hydrogen supply amount is delayed instead of the air supply amount. The same parts as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 8 is a timing chart showing the contents of the flooding prevention control of the sixth embodiment. In the sixth embodiment, as shown in FIG. 8, when it is determined that the output of the fuel cell 10 suddenly decreases, the control device 40 cools the fuel cell 10 in synchronization with the output request value of the fuel cell 10. Reduce the amount. Further, the air supply amount is decreased in synchronization with the output request value of the fuel cell 10. At this time, the hydrogen supply amount is not synchronized with the required output value of the fuel cell 10 and is not changed as it is. Then, the hydrogen supply amount is reduced to the required hydrogen supply amount corresponding to the required output value of the fuel cell 10 after the elapse of the predetermined time t1.

  In the configuration of this fourth embodiment, after the required output value of the fuel cell 10 has suddenly decreased, hydrogen is supplied in an excessive supply amount only for a predetermined time t1, so that the fuel cell can be produced with a gas flow due to excess hydrogen. The water accumulated in the hydrogen electrode side passage inside 10 can be pushed out. As a result, it is possible to suppress the retention of moisture in the gas diffusion layer, and it is possible to suppress a decrease in the power generation efficiency of the fuel cell 10 when the required output value of the fuel cell 10 rapidly decreases.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described with reference to FIG. The seventh embodiment is different from the sixth embodiment in that the hydrogen supply amount is increased before the required hydrogen supply amount corresponding to the required output value of the fuel cell 10 is decreased. The same parts as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 9 is a timing chart showing details of the flooding prevention control of the seventh embodiment. In the seventh embodiment, as shown in FIG. 9, when it is determined that the output of the fuel cell 10 is suddenly reduced, the control device 40 cools the fuel cell 10 in synchronization with the output request value of the fuel cell 10. Reduce the amount. Further, the air supply amount is decreased in synchronization with the output request value of the fuel cell 10. At this time, the hydrogen supply amount is not synchronized with the required output value of the fuel cell 10, but is increased by a predetermined amount. Then, the hydrogen supply amount is reduced to the required hydrogen supply amount corresponding to the required output value of the fuel cell 10 after the elapse of the predetermined time t1.

  Also in the configuration of the seventh embodiment, the same effects as in the sixth embodiment can be obtained. Further, by increasing the hydrogen supply amount for a predetermined time t1 as in the seventh embodiment, drying of the hydrogen electrode side passage of the fuel cell 10 can be promoted, and drying can be performed in a shorter time.

(Other embodiments)
In the above embodiment, the cooling amount of the fuel cell 10 is adjusted by adjusting the cooling water flow rate by adjusting the rotational speed of the water pump 31 and by adjusting the blowing amount by adjusting the rotational speed of the blower fan 33. The cooling amount of the fuel cell 10 may be adjusted by performing only one of the rotation speed adjustment of the water pump 31 and the rotation speed adjustment of the blower fan 33. When only the rotation speed adjustment of the water pump 31 is performed, the power consumption of the blower fan 33 can be reduced. When only the rotation speed adjustment of the blower fan 33 is performed, the power consumption of the water pump 31 can be reduced.

It is a conceptual diagram of the fuel cell system of the said 1st Embodiment. It is a conceptual diagram of the fuel cell of FIG. It is a timing chart which shows flooding prevention control of a 1st embodiment. It is a timing chart which shows flooding prevention control of a 2nd embodiment. It is a timing chart which shows flooding prevention control of a 3rd embodiment. It is a timing chart which shows flooding prevention control of a 4th embodiment. It is a timing chart which shows flooding prevention control of a 5th embodiment. It is a timing chart which shows flooding prevention control of a 6th embodiment. It is a timing chart which shows flooding prevention control of a 7th embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 21 ... Air supply device, 23 ... Hydrogen supply device, 24 ... Shut valve, 25 ... Regulator, 31 ... Water pump, 32 ... Radiator (radiator), 33 ... Blower fan, 40 ... Control device.

Claims (7)

A fuel cell (10) for generating electrical energy by an electrochemical reaction between an oxidant gas and a fuel gas;
Output request value acquisition means (40) for acquiring an output request value for the fuel cell (10);
Oxidant supply amount adjusting means (21, 40) for adjusting the supply amount of the oxidant gas to the fuel cell (10) based on the output request value;
Fuel supply amount adjusting means (24, 25, 40) for adjusting the supply amount of fuel gas to the fuel cell (10) based on the output request value;
Cooling amount adjusting means (31, 33, 40) for adjusting the amount of cooling by the cooling means (30 to 33) for cooling the fuel cell (10) based on the required output value,
The cooling amount adjusting means (31, 33, 40) sets the cooling amount of the fuel cell (10) to the required output value at the predetermined time when the rate of decrease of the required output value at a predetermined time exceeds a predetermined value. Correspondingly reduced,
The oxidant supply amount adjusting means (21, 40) and the fuel supply amount adjusting means (24, 25, 40) are configured so that the oxidant gas is supplied when a reduction rate of the required output value at a predetermined time exceeds a predetermined value. The fuel cell system is characterized in that both the supply amount of fuel and the supply amount of the fuel gas are reduced corresponding to the output request value after a predetermined time has elapsed from the predetermined time point. The oxidant supply amount adjusting means (21, 40) reduces the supply amount of the oxidant gas corresponding to the output request value after the first predetermined time has elapsed from the predetermined time point, and the fuel supply amount adjusting means. (24, 25, 40) according to claim 1, wherein the supply amount of the fuel gas is decreased corresponding to the output required value after a second predetermined time longer than the first predetermined time. The fuel cell system described. The fuel supply amount adjusting means (24, 25, 40) reduces the supply amount of the fuel gas corresponding to the required output value after a first predetermined time has elapsed from the predetermined time point, thereby adjusting the oxidant supply amount. The means (21, 40) is characterized in that the supply amount of the oxidant gas is reduced in correspondence with the required output value after the elapse of a second predetermined time longer than the first predetermined time. The fuel cell system described. A fuel cell (10) for generating electrical energy by an electrochemical reaction between an oxidant gas and a fuel gas;
Output request value acquisition means (40) for acquiring an output request value for the fuel cell (10);
Oxidant supply amount adjusting means (21, 40) for adjusting the supply amount of the oxidant gas to the fuel cell (10) based on the output request value;
Fuel supply amount adjusting means (24, 25, 40) for adjusting the supply amount of fuel gas to the fuel cell (10) based on the output request value;
Cooling amount adjusting means (31, 33, 40) for adjusting the amount of cooling by the cooling means (30 to 33) for cooling the fuel cell (10) based on the required output value,
The cooling amount adjusting means (31, 33, 40) sets the cooling amount of the fuel cell (10) to the required output value at the predetermined time when the rate of decrease of the required output value at a predetermined time exceeds a predetermined value. Correspondingly reduced,
The oxidant supply amount adjusting means (21, 40) and the fuel supply amount adjusting means (24, 25, 40) are configured so that the oxidant gas is supplied when a reduction rate of the required output value at a predetermined time exceeds a predetermined value. Either the supply amount of fuel or the supply amount of the fuel gas is reduced corresponding to the output request value at the predetermined time point, and the other is reduced corresponding to the output request value after a predetermined time has elapsed from the predetermined time point. Fuel cell system characterized by The oxidant supply amount adjusting means (21, 40) and the fuel supply amount adjusting means (24, 25, 40) are configured so that the oxidant gas is supplied when a reduction rate of the required output value at a predetermined time exceeds a predetermined value. Either the supply amount of the fuel gas or the supply amount of the fuel gas is decreased at the predetermined time corresponding to the output request value, the other is increased at the predetermined time, and the output is output after a predetermined time has elapsed from the predetermined time. The fuel cell system according to claim 4, wherein the fuel cell system is lowered corresponding to the required value. The cooling means (30 to 33) includes a pump (31) that circulates a heat medium in the fuel cell (10), and a radiator (that emits heat of the fuel cell (10) to the outside via the heat medium. 32) and a blower fan (33) for blowing air to the radiator (32),
The amount of cooling of the fuel cell (10) is adjusted by either adjusting the amount of circulation of the heat medium by the pump (31) or adjusting the amount of blast by the fan (33). The fuel cell system according to any one of claims 1 to 5, wherein the fuel cell system is adjusted. When the rate of decrease in the output request value exceeds a predetermined value, the output request value after a predetermined time set within 30 seconds from the predetermined time point is ½ of the output request value at the predetermined time point. The fuel cell system according to any one of claims 1 to 6, wherein:

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