JP5557579B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system.

  Conventionally, as a fuel cell mounted on a vehicle, for example, a membrane electrode structure is formed by sandwiching a solid polymer electrolyte membrane from both sides with an anode electrode and a cathode electrode, and a pair of separators are arranged on both sides of the membrane electrode structure. A flat unit fuel cell (hereinafter referred to as a unit cell) is configured, and a plurality of unit cells are stacked to form a fuel cell stack (hereinafter referred to as a fuel cell). In a fuel cell vehicle, power can be generated by supplying a reaction gas comprising anode gas and cathode gas to the fuel cell, and a motor for rotating the drive shaft of the wheel can be driven by this electric power. It is configured.

  Specifically, hydrogen gas is supplied as an anode gas (fuel gas) between the anode electrode and the separator in the fuel cell described above, and air is supplied as a cathode gas (oxidant gas) between the cathode electrode and the separator. Supply. As a result, hydrogen ions generated by the catalytic reaction at the anode electrode pass through the solid polymer electrolyte membrane and move to the cathode electrode, causing an electrochemical reaction with oxygen in the air at the cathode electrode, thereby generating power. It should be noted that water is generated inside the fuel cell with this power generation.

  In a fuel cell system equipped with such a fuel cell, if the cathode gas (oxygen) remains in the flow path while the system is stopped, the potential on the anode side (in-plane current) increases at the next system startup. There are problems that the power generation stability at the time of start-up is lowered and the fuel cell is deteriorated.

  Therefore, in order to solve the above-described problems, in Patent Document 1, hydrogen is removed by a controller that limits the pressure difference between the anode gas and the cathode gas inside the cell and an external short circuit, thereby preventing deterioration in battery performance. To stop the fuel cell, the anode gas supply valve was closed, and the molar ratio of hydrogen / oxygen contained in the anode gas and the cathode gas separated by the electrolyte membrane was 2/1 or less. Some proposals have been made to close the air supply valve to the fuel cell.

  Further, in Patent Document 2, the fuel gas supply / discharge system and the oxidizing gas for the fuel cell are suppressed for the purpose of suppressing the power generation performance from being reduced due to oxidation of the supported carbon in the cathode side catalyst when the system is left standing. Calculate the molar amount of hydrogen and oxygen in the supply / exhaust system, and control the molar ratio of chemically reactive hydrogen and oxygen in the fuel gas and oxidizing gas to 2 or more when the fuel cell is stopped Has been proposed.

JP 2005-268086 A JP 2007-265786 A

Incidentally, the fuel cell systems of Patent Documents 1 and 2 are configured to shut off the supply of anode gas and cathode gas when the system is stopped or after the system is stopped. In these conventional fuel cell systems, hydrogen and oxygen are not supplied. When only the molar ratio satisfies a desired condition, the supply of the reaction gas (anode gas and cathode gas) is cut off.
However, the magnitude of the negative pressure generated in the anode gas flow path after the supply of the reaction gas is interrupted depends on the magnitude of the pressure of the anode gas. Therefore, if the anode gas pressure is not taken into account when determining the timing for sealing the cathode gas, even if the molar ratio of hydrogen to oxygen meets the desired conditions, the pressure balance will be lost and power generation will be There is a risk that stability will be reduced.

  Therefore, the present invention has been made in view of the above circumstances, and provides a fuel cell system that can improve power generation stability at the time of system startup and can suppress deterioration of the fuel cell. is there.

In order to solve the above problems, the invention described in claim 1 includes an anode electrode that receives supply of anode gas and a cathode electrode that receives supply of cathode gas, and generates power by supplying the anode gas and cathode gas. And a cathode gas flow passage (for example, the cathode gas flow passage 47 in the embodiment) through which the cathode gas flows, and the cathode gas to the cathode electrode is provided. Cathode gas sealing means (for example, the sealing valves 56 and 57 in the embodiment) capable of sealing the inflow of gas, and a control device (for example, the control device 45 in the embodiment) for controlling the cathode gas sealing means, In the fuel cell system (for example, the fuel cell system 10 in the embodiment), When the pressure in the cathode gas flow passage is atmospheric pressure, the anode gas flow passage (for example, the anode gas flow passage 46 in the embodiment) through which the anode gas flows and the anode gas in the cathode gas flow passage are included in the anode gas flow passage. An anode gas pressure calculation unit (for example, an embodiment) that calculates an anode gas pressure in the anode gas flow passage in which a molar ratio (hydrogen / oxygen) of hydrogen to be contained and oxygen contained in the cathode gas is 2 or more Cathode gas sealing timing for calculating the cathode gas sealing timing by the cathode gas sealing means based on the anode gas pressure calculated by the anode gas pressure calculating unit 62) Calculation unit (for example, cathode gas sealing timing calculation in the embodiment) 64), wherein the sealing timing, is configured to be lower as the anode gas pressure is high, when stopping the power generation of the fuel cell, the calculated in the anode gas pressure calculating section as the anode gas pressure, thereby adjusting the pressure of the anode gas flow path, and seal the cathode gas sealing means at the sealing timing calculated in the cathode gas sealing timing calculation unit, wherein The anode gas pressure and the cathode gas pressure are both maintained at a negative pressure after the cathode gas sealing means is sealed .

  According to a second aspect of the present invention, the control device further includes a wet state detection unit (for example, a wet state detection unit 63 in the embodiment) for detecting a wet state of the anode gas flow passage, and the cathode gas sealing. The timing calculation unit calculates the sealing timing of the cathode gas by the cathode gas sealing means based on the wet state of the anode gas flow passage detected by the wet state detection unit, and the sealing timing is The anode gas is configured to become slower as the humidity becomes lower.

  According to the first aspect of the present invention, since the cathode gas inflow is sealed in a state where the hydrogen pressure is such that the molar ratio of hydrogen to oxygen is 2 or more, it is active in both the anode side and the cathode side in a short time. An environment in which only hydrogen is present as a gas can be formed, and a potential increase at the next system startup can be suppressed. In addition, since the operation timing of the cathode gas sealing means is calculated based on the anode gas pressure, the burden on the constituent members of the fuel cell system can be reduced. Therefore, it is possible to improve the power generation stability at the time of starting the system and to suppress the deterioration of the fuel cell. Furthermore, sealing can be performed with hydrogen remaining on both the anode and cathode sides, and the amount of anode gas input at system startup can be greatly reduced. Shortening can be achieved.

  According to the second aspect of the present invention, when the anode gas flow passage is in the WET state, it becomes a resistance to diffusion of hydrogen to the cathode side, so that the time until the anode gas pressure decreases to the atmospheric pressure is slow. Become. Further, in the WET state, hydrogen diffusion becomes dull, so that when the entire amount of hydrogen on the anode side is not diffused to the cathode side, the decrease in the anode gas pressure is small in the first place. That is, the negative pressure on the anode side after the cathode side sealing is smaller than that in the DRY state. Therefore, the cathode gas sealing means can be sealed quickly. By quickly sealing the cathode gas sealing means, the reaction gas (anode gas and cathode gas) can be supplied at a timing when the molar ratio of hydrogen to oxygen satisfies the desired condition (molar ratio of 2 or more). It is possible to approach shut off, sealing with hydrogen remaining on both electrodes, improving power generation stability at system startup, and suppressing deterioration of the fuel cell Can do. Further, since the sealing timing of the cathode gas sealing means is calculated based on the wet state of the anode gas flow passage, the cathode gas can be sealed at a more optimal timing.

1 is a schematic configuration diagram of a fuel cell system in an embodiment of the present invention. It is a schematic block diagram of the control apparatus in embodiment of this invention. It is a flowchart which shows the method of sealing the sealing valve by the side of the cathode of the fuel cell system in embodiment of this invention. It is a graph which shows the relationship between the anode gas pressure and cathode side sealing timing in embodiment of this invention. It is a time chart at the time of sealing the sealing valve by the side of the cathode of the fuel cell system in the embodiment of the present invention.

  Next, an embodiment of a fuel cell system according to the present invention will be described with reference to FIGS. In the present embodiment, a case where the fuel cell system is mounted on a vehicle will be described.

(Fuel cell system)
FIG. 1 is a schematic configuration diagram of a fuel cell system.
As shown in FIG. 1, the fuel cell 11 of the fuel cell system 10 is a solid polymer membrane fuel cell that generates electric power by an electrochemical reaction between an anode gas such as hydrogen gas and a cathode gas such as air. Specifically, in the fuel cell 11, a membrane electrode structure is formed by sandwiching a solid polymer electrolyte membrane from both sides with an anode electrode and a cathode electrode, and a pair of separators are arranged on both sides of the membrane electrode structure to form a flat plate shape. And a plurality of unit cells are stacked. An anode gas supply pipe 23 is connected to the anode gas supply communication hole 13 (inlet side of the anode gas passage 21) formed in the fuel cell 11, and a hydrogen tank 30 is connected to the upstream end thereof. Yes. A cathode gas supply pipe 24 is connected to the cathode gas supply communication hole 15 (inlet side of the cathode gas flow path 22) formed in the fuel cell 11, and an air compressor 33 is connected to the upstream end thereof. Yes. Further, an anode offgas discharge communication hole 14 (cathode gas flow path 22) is connected to the anode offgas discharge communication hole 14 (exit side of the anode gas flow path 21) formed in the fuel cell 11. Is connected to a cathode offgas discharge pipe 38. Here, in this embodiment, the anode gas flow path 21, the anode gas supply pipe 23, and the anode off gas discharge pipe 35 constitute the anode gas flow path 46, and the cathode gas flow path 22, the cathode gas supply pipe 24, and the cathode The off gas discharge pipe 38 constitutes a cathode gas flow passage 47.

  Further, the hydrogen gas supplied from the hydrogen tank 30 to the anode gas supply pipe 23 is decompressed by a regulator (not shown), then passes through the ejector 26 and is supplied to the anode gas flow path 21 of the fuel cell 11. An electromagnetically driven solenoid valve 25 is provided in the vicinity of the downstream side of the hydrogen tank 30 so that the supply of hydrogen gas from the hydrogen tank 30 can be shut off.

  The anode off gas discharge pipe 35 is connected to the ejector 26 so that the anode off gas discharged through the fuel cell 11 can be reused as the anode gas of the fuel cell 11 again. Further, the anode off gas discharge pipe 35 is provided with two pipes branched in the middle, and a drain discharge pipe 36 and a purge gas discharge pipe 37 are connected thereto. The drain discharge pipe 36 and the purge gas discharge pipe 37 are both connected to the dilution box 31 downstream thereof. The drain discharge pipe 36 is provided with an electromagnetically driven drain valve 51, and the purge gas discharge pipe 37 is provided with an electromagnetically driven purge valve 52. A catch tank 53 is provided as a gas-liquid separator at a branch point between the anode off-gas discharge pipe 35 and the drain discharge pipe 36.

  Next, air (cathode gas) is pressurized by the air compressor 33, passes through the cathode gas supply pipe 24, and is then supplied to the cathode gas flow path 22 of the fuel cell 11. After this oxygen in the air is used as an oxidizing agent for power generation, it is discharged from the fuel cell 11 to the cathode offgas discharge pipe 38 as cathode offgas. The cathode offgas discharge pipe 38 is connected to the dilution box 31 and then exhausted to the outside of the vehicle. A back pressure valve 34 is provided in the cathode off gas discharge pipe 38. In addition, a humidifier 39 is provided between the cathode gas supply pipe 24 and the cathode offgas discharge pipe 38. The humidifier 39 humidifies the cathode gas by the movement of moisture contained in the cathode off gas. Further, the cathode gas supply pipe 24 and the cathode offgas discharge pipe 38 are respectively provided with electromagnetically driven sealing valves 56 and 57 so that the cathode gas can be sealed in the cathode gas flow passage 47. It is configured.

  Further, in the cathode gas supply pipe 24 connecting the air compressor 33 and the fuel cell 11, the pipe is branched and one end of the scavenging gas introduction pipe 54 is connected. The other end of the scavenging gas introduction pipe 54 is connected between the ejector 26 and the fuel cell 11 in the anode gas supply pipe 23. That is, the air pressurized by the air compressor 33 can be supplied to the anode gas passage 21 of the fuel cell 11. The scavenging gas introduction pipe 54 is provided with an electromagnetically driven solenoid valve 55 so that the supply of air from the air compressor 33 can be shut off.

  Further, the anode gas supply pipe 23 is provided with a pressure sensor 41 capable of detecting the anode gas pressure in the anode gas flow passage 46. The cathode gas supply pipe 24 is provided with a pressure sensor 42 that can detect the cathode gas pressure in the cathode gas flow passage 47. Further, the fuel cell 11 is provided with a voltage sensor 43 capable of detecting the generated voltage (output).

  Detection results (sensor output) from the pressure sensors 41 and 42 and the voltage sensor 43 are transmitted to a control unit (ECU) 45, and based on the detection results, the anode gas and cathode gas of the fuel cell system 10 are sealed. It is configured to be able to perform control for setting timing (described in detail later).

  FIG. 2 is a schematic block diagram of the control device 45. As shown in FIG. 2, the control device 45 includes a humidity calculating unit 61 that calculates the humidity in the anode gas flow passage 46, and a molar ratio between hydrogen contained in the anode gas and oxygen contained in the cathode gas (hydrogen / oxygen). ) Is an anode gas pressure calculation unit 62 for calculating the anode gas pressure in the anode gas flow passage 46, and whether or not the humidity in the anode gas flow passage 46 is higher than a predetermined humidity set in advance. The wet state determination unit 63 for determining, the cathode gas sealing timing calculation unit 64 for calculating the sealing timing of the sealing valves 56 and 57 based on the calculated anode gas pressure, and the sealing of the sealing valves 56 and 57 And a timing unit 65 that counts the stop timing.

  The control device 45 controls the regulator and the electromagnetic valve 25 according to the output required for the fuel cell 11 and supplies hydrogen gas of a predetermined state quantity (flow rate and pressure) from the hydrogen tank 30 to the fuel cell 11. Can be done. The control device 45 drives the air compressor 33 according to the output required for the fuel cell 11 to supply a predetermined amount of air to the fuel cell 11 and controls the back pressure valve 34 to control the cathode gas flow path. It is comprised so that the state quantity (flow volume, pressure) of the air to 22 can be adjusted.

(Cathode gas sealing method)
Next, a cathode gas sealing method of the fuel cell system 10 in the present embodiment will be described.
FIG. 3 is a flowchart showing a cathode gas sealing method of the fuel cell system 10. This flowchart starts from the time when the ignition switch is turned off.

  In step S11, the humidity calculator 61 calculates the humidity in the anode gas flow passage 46, and the process proceeds to step S12. In order to calculate the humidity in the anode gas flow passage 46, for example, a dew point meter and a thermometer (both not shown) are attached to predetermined positions of the anode gas flow passage 46, and the dew point meter and the thermometer are detected. The humidity may be calculated from the value.

  In step S12, in the anode gas pressure calculation unit 62, when the molar ratio (hydrogen / oxygen) between hydrogen contained in the anode gas and oxygen contained in the cathode gas is 2 or more, The anode gas pressure is calculated, and the process proceeds to step S13.

  In step S13, the wet state determination unit 63 determines whether or not the humidity in the anode gas flow passage 46 calculated in step S11 is higher than a predetermined humidity (predetermined threshold value) set in advance. If it is larger (in the case of the WET environment), the process proceeds to step S14, and if it is equal to or smaller than the predetermined threshold value (in the case of the DRY environment), the process proceeds to step S16.

  In step S14, the cathode gas sealing timing calculation unit 64 calculates the sealing timing of the sealing valves 56 and 57 based on the calculated anode gas pressure, and proceeds to step S15. Here, for example, the graph of FIG. 4 is stored in the cathode gas sealing timing calculation unit 64. As shown in FIG. 4, the relationship between the anode gas pressure and the cathode side sealing timing in the case of the WET environment and the case of the DRY environment is stored as a diagram. In step S14, the sealing timing of the sealing valves 56 and 57 is calculated using a diagram in the case of the WET environment.

  If the sealing valves 56 and 57 are sealed, hydrogen and oxygen are consumed by a chemical reaction, and a negative pressure is generated on the anode side. If the anode gas pressure is raised to increase the molar ratio to 2 or more and the sealing valves 56 and 57 are sealed, will hydrogen and oxygen disappear due to chemical reaction in both electrodes during cathode side sealing? It is possible to create a state where oxygen is lost and only hydrogen remains. The more surplus hydrogen molecules, that is, the higher the anode gas pressure, the more hydrogen remains. However, negative pressure is generated because hydrogen undergoes a chemical reaction until oxygen in the sealed air is exhausted.

  If the negative pressure is within a range that does not affect the durability of the fuel cell 11 and other components of the fuel cell system 10, it is better to seal the sealing valves 56 and 57 earlier during the cathode side sealing. It is possible to form a state in which hydrogen remains.

  On the other hand, the influence of the negative pressure can be reduced by delaying the sealing timing of the sealing valves 56 and 57 with respect to the negative pressure. This is because as the amount of air introduced to the cathode side increases, the amount of oxygen diffusing to the anode side increases and the amount of nitrogen remaining on the cathode side increases. This reduces the remaining amount of surplus hydrogen molecules sealed at both electrodes, but if the amount is within the potential range that is effective for degradation during cathode side sealing and anode side potential at the next start-up. Can be tolerated.

  The anode gas pressure and the cathode sealing timing in FIG. 4 are examples in which the higher the anode gas pressure, the slower the cathode sealing timing tends to be, but the negative pressure due to the sealing described above is the durability of the components. It can be arbitrarily determined from the viewpoint of influence on the anode potential and the anode potential generated by the surplus hydrogen molecules to be sealed.

  In step S15, the timing unit 65 measures the sealing timing calculated in step S14. When a predetermined time elapses, the sealing valves 56 and 57 are sealed, and the process ends.

  On the other hand, in step S16, since the humidity in the anode gas flow passage 46 is equal to or lower than the predetermined threshold value, it is determined that the DRY environment is set, and the DRY environment flag is set and the process proceeds to step S17.

  In step S17, the cathode gas sealing timing calculation unit 64 calculates the sealing timing of the sealing valves 56 and 57 based on the calculated anode gas pressure, and proceeds to step S18. Since the DRY environment flag is set in step S16, the sealing timing is calculated using the diagram for the DRY environment in FIG.

  In step S18, the timing unit 65 measures the sealing timing calculated in step S17. When a predetermined time elapses, the sealing valves 56 and 57 are sealed, and the process ends.

  FIG. 5 is a time chart showing the flow of the flowchart of FIG. As shown in FIG. 5, after the ignition switch is turned off, the anode gas pressure in the anode gas flow passage 46 is adjusted so as to be the anode gas pressure calculated in the anode gas pressure calculation unit 62 to obtain a desired pressure. The electromagnetic valve 25 is closed at the point of time (base point of cathode sealing timing), and the anode gas pressure is maintained as it is. In this state, the compressor 33 is stopped, and the sealing valves 56 and 57 are sealed at the sealing timing calculated by the cathode gas sealing timing calculation unit 64. With this configuration, it is possible to form an environment in which only hydrogen as an active gas exists in both the anode side and the cathode side in a short time, and to suppress an increase in potential at the next system startup.

  Specifically, after the ignition switch is turned off, various stop processes are performed before the compressor 33 is stopped, and the compressor 33 is stopped at the system stop timing. The cathode gas pressure becomes atmospheric pressure almost simultaneously with the stop of the compressor 33. A little before the system stop timing (while the compressor 33 is being driven) and when the anode gas pressure reaches a desired pressure, the anode-side electromagnetic valve 25, drain valve 51 and purge valve 52 are first closed. .

  Thereafter, in a few minutes, the anode gas pressure decreases to atmospheric pressure. In the initial stage, since the anode gas pressure is higher than the cathode gas pressure (atmospheric pressure), the diffusion of the reaction gas from the anode side to the cathode side becomes dominant, and the reaction gas is consumed by the chemical reaction in the diffusion layer or electrode part. Is done.

  After the anode gas pressure reaches atmospheric pressure (the cathode gas and anode gas pressure equilibrium state), the hydrogen on the anode side is consumed by a chemical reaction and becomes water on the cathode side. Since the speed of air diffusion is different, that is, the chemical reaction of hydrogen is faster, the anode side is temporarily under negative pressure.

  Thereafter, when the cathode side is not sealed, the pressure on the anode side and the cathode side both rises and returns to atmospheric pressure due to the diffusion of air from the cathode side, but the cathode side sealing is performed as in this embodiment. By closing the valves 56 and 57, there is no introduction of new air to the cathode side, so there is no return to atmospheric pressure, and the negative pressure state is maintained. That is, both the anode side and the cathode side have negative pressure. In addition, the negative pressure after sealing becomes small, so that the timing which seals the sealing valves 56 and 57 is late | slow.

  Here, when the anode gas pressure is increased to an ideal molar ratio (hydrogen: oxygen = 2: 1), the anode gas pressure is high, and the cathode gas pressure becomes atmospheric pressure and becomes a closed space. In this closed space, each gas is consumed and water is generated by a chemical reaction between the anode gas (hydrogen) and the cathode gas (oxygen). As a result, the anode gas pressure and the cathode gas pressure are reduced, and both the anode side and the cathode side become negative pressures. If the molar ratio is 2: 1, all hydrogen and oxygen become water by chemical reaction, so that only water and nitrogen gas remain in the closed space. By sealing the sealing valves 56 and 57, there is no inflow of reaction gas (air) from the outside, so the negative pressure state is continued.

  When the anode gas pressure is increased so that the molar ratio of hydrogen to oxygen becomes 2 or more, all oxygen in the cathode gas becomes water by a chemical reaction, and excess hydrogen remains in the closed space. As a result, water, nitrogen, and hydrogen remain in the closed space, and hydrogen is distributed to both electrodes by diffusion.

  On the other hand, when the molar ratio is less than 2, all hydrogen of the anode gas becomes water by chemical reaction, and excess cathode gas (oxygen) remains in the closed space. As a result, water, nitrogen, and oxygen remain in the closed space, and oxygen is distributed to both electrodes by diffusion.

  According to the present embodiment, in order to seal the inflow of the cathode gas with an anode gas pressure at which the molar ratio of the anode gas (hydrogen) to the cathode gas (oxygen) is 2 or more, It is possible to form an environment in which only hydrogen is present as an active gas at both electrodes on the cathode side, and an increase in potential at the next system startup can be suppressed. In addition, since the sealing timing of the sealing valves 56 and 57 is calculated based on the anode gas pressure, the burden on the constituent members of the fuel cell system 10 can be reduced. Therefore, it is possible to improve the power generation stability at the time of starting the system and to suppress the deterioration of the fuel cell 11.

  In addition, since the sealing timing of the sealing valves 56 and 57 is calculated based on the wet state of the anode gas flow passage 46, the cathode gas can be sealed at a more optimal timing.

  Further, since the sealing timing of the sealing valves 56 and 57 is delayed as the humidity of the anode gas decreases, the amount of anode gas to be input at the time of starting the system can be greatly reduced, and the hydrogen on the anode side The replacement completion time can be shortened, and the power generation stability at the time of starting the system can be improved.

  It should be noted that adjusting the hydrogen and oxygen so as to have an ideal molar ratio is effective for suppressing potential and preventing deterioration during soaking of the fuel cell system 10 and during system startup. For example, during soaking and during system startup. If it is effective for prevention of deterioration by suppressing the anode potential to less than 0.6V, the relationship between the potential in the soak and the anode gas pressure at the time of system shutdown is used as an ideal potential instead of the molar ratio. Therefore, the system can be stopped at the anode gas pressure and the cathode gas can be sealed.

  In addition, after the ideal potential and anode gas pressure are calculated, the negative pressure state predicted from the anode gas pressure is also obtained in advance by experiments or the like, so that the negative pressure is an allowable negative pressure. It is possible to determine the sealing timing for sealing the sealing valves 56 and 57.

  Note that the present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention. That is, the specific structure and configuration described in the embodiment are merely examples, and can be changed as appropriate.

For example, in the present embodiment, the wet state of the anode gas flow passage is detected, but it is not always necessary to provide it.
In the present embodiment, the DRY environment flag is set when the humidity of the anode gas is equal to or lower than the predetermined threshold. However, the WET environment flag may be set when the humidity is higher than the predetermined threshold. Good.

  DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 11 ... Fuel cell 45 ... Control apparatus 46 ... Anode gas flow path 47 ... Cathode gas flow path 56 ... Sealing valve (cathode gas sealing means) 57 ... Sealing valve (cathode gas sealing means) 62 ... Anode gas pressure calculation unit 63 ... Wet state detection unit 64 ... Cathode gas sealing timing calculation unit

Claims (2)

A fuel cell having an anode electrode supplied with an anode gas and a cathode electrode supplied with a cathode gas, and generating power by supplying the anode gas and the cathode gas;
A cathode gas sealing means provided in a cathode gas flow passage through which the cathode gas flows, and capable of sealing the inflow of the cathode gas to the cathode electrode;
In a fuel cell system comprising a control device for controlling the cathode gas sealing means,
The control device includes:
When the pressure in the cathode gas flow passage is atmospheric pressure, the anode gas flow passage through which the anode gas flows, the hydrogen contained in the anode gas in the cathode gas flow passage, the oxygen contained in the cathode gas, An anode gas pressure calculation unit for calculating an anode gas pressure in the anode gas flow passage where the molar ratio (hydrogen / oxygen) is 2 or more;
A cathode gas sealing timing calculation unit that calculates a sealing timing of the cathode gas by the cathode gas sealing means based on the anode gas pressure calculated by the anode gas pressure calculation unit,
The sealing timing is configured to be delayed as the anode gas pressure increases,
When stopping the power generation of the fuel cell, so that the anode gas pressure calculated in the previous SL anode gas pressure calculating unit, thereby adjusting the pressure of the anode gas circulation path, before Symbol cathode gas sealing timing wherein at the sealing timing calculated in the calculation unit to seal the cathode gas sealing means,
After the cathode gas sealing means is sealed, the anode gas pressure and the cathode gas pressure are both held at negative pressure . The control device further includes a wet state detection unit that detects a wet state of the anode gas flow passage,
The cathode gas sealing timing calculation unit calculates the sealing timing of the cathode gas by the cathode gas sealing means based on the wet state of the anode gas flow path detected by the wet state detection unit,
The fuel cell system according to claim 1, wherein the sealing timing is configured to be delayed as the humidity of the anode gas decreases.

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