Diagnosing method for sealing condition of fuel cell and fuel cell system

Abstract

To provide a technique for diagnosing whether the cathode gas inlet / outlet and anode gas inlet / outlet of a fuel cell are sealed.SOLUTION: The diagnosing method for the sealing state of a fuel cell includes pressurizing the interior of the fuel cell to a predetermined pressure higher than atmospheric pressure by supplying anode gas to the fuel cell before stopping the fuel cell, maintaining a sealed state in which the anode gas inlet / outlet and cathode gas inlet / outlet are sealed during a fuel cell's shutdown, and determining the integrity of the sealed state by comparing the internal pressure of the fuel cell measured prior to restarting the fuel cell and the atmospheric pressure.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for diagnosing the sealing condition of a fuel cell and a fuel cell system. [Background technology]

[0002] A method is known in which a control valve in a gas flow path is closed when the fuel cell is stopped to detect cross leakage caused by permeation of reactant gases through an electrolyte membrane (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-162240 Summary of the Invention [Problem to be solved by the invention]

[0004] If the cathode gas inlet and outlet and the anode gas inlet and outlet are not properly sealed while the fuel cell is stopped, the fuel cell may deteriorate. Therefore, there is a need for a technology to diagnose whether the cathode gas inlet and outlet and the anode gas inlet and outlet of a fuel cell are properly sealed. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to a first aspect of the present disclosure, there is provided a method for diagnosing the sealed state of a fuel cell, which comprises: before shutting down the fuel cell, pressurizing the inside of the fuel cell to a predetermined pressure higher than atmospheric pressure by supplying anode gas to the fuel cell; maintaining a sealed state in which the anode gas inlet and cathode gas inlet of the fuel cell are sealed while the fuel cell is shut down; and determining whether the sealed state is good or bad by comparing the internal pressure of the fuel cell measured before restarting the fuel cell with atmospheric pressure. According to this embodiment of the method for diagnosing the sealing state of a fuel cell, it is possible to diagnose whether the cathode gas inlet and outlet and the anode gas inlet and outlet of the fuel cell are properly sealed. (2) In the method for diagnosing the sealing state of a fuel cell of the above form, the predetermined pressure is a pressure at which the pressure in the cathode gas internal flow path and the pressure in the anode gas internal flow path provided inside the fuel cell are higher than atmospheric pressure when the sealing state is good and an equilibrium state is reached in which the pressure in the cathode gas internal flow path and the pressure in the anode gas internal flow path are balanced, and if the internal pressure of the fuel cell measured before restarting the fuel cell is higher than atmospheric pressure, the sealing state may be determined to be good, and if the internal pressure of the fuel cell measured before restarting the fuel cell is not higher than atmospheric pressure, the sealing state may be determined to be poor. According to the method for diagnosing the sealing state of a fuel cell of this aspect, it is possible to prevent the sealing state from being erroneously determined to be poor when it is actually good. (3) According to a second aspect of the present disclosure, there is provided a fuel cell system comprising: a fuel cell; an anode gas supply source that supplies anode gas to the fuel cell; multiple valves that seal the anode gas inlet and outlet and cathode gas inlet and outlet of the fuel cell; a pressure sensor that measures the internal pressure of the fuel cell; and a control device that controls the multiple valves. Before the fuel cell is shut down, the control device pressurizes the interior of the fuel cell to a predetermined pressure higher than atmospheric pressure by supplying anode gas from the anode gas supply source to the fuel cell, and while the fuel cell is shut down, the control device maintains a sealed state in which the anode gas inlet and outlet and cathode gas inlet and outlet of the fuel cell are sealed, and determines whether the sealed state is good or bad by comparing the internal pressure of the fuel cell measured using the pressure sensor with atmospheric pressure before the fuel cell is restarted. According to this aspect of the fuel cell system, it is possible to diagnose whether the cathode gas inlet and outlet and the anode gas inlet and outlet of the fuel cell are properly sealed. The present disclosure can be realized in various forms other than a method for diagnosing the sealing state of a fuel cell and a fuel cell system, for example, a method for diagnosing an abnormality in a fuel cell system. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a first explanatory diagram showing the configuration of a fuel cell system. [Figure 2] FIG. 2 is a second explanatory diagram showing the configuration of the fuel cell system. [Figure 3] FIG. 2 is an explanatory diagram showing the configuration of a control device. [Figure 4] 10 is a flowchart showing the steps of a method for diagnosing the sealing state of a gas inlet / outlet. [Figure 5] FIG. 10 is an explanatory diagram showing the internal pressure of the fuel cell when the gas inlet and outlet ports are well sealed. [Figure 6] FIG. 10 is an explanatory diagram showing the internal pressure of the fuel cell when the gas inlet / outlet port is not properly sealed. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. First embodiment: FIG. 1 is a first explanatory diagram showing the configuration of a fuel cell system 10 in a first embodiment. FIG. 2 is a second explanatory diagram showing the configuration of the fuel cell system 10 in the first embodiment. The fuel cell system 10 in this embodiment is mounted on a fuel cell electric vehicle (FCEV). However, the fuel cell system 10 does not have to be mounted on a fuel cell vehicle, and may be, for example, a stationary type. As shown in FIG. 1, the fuel cell system 10 includes a fuel cell 100, a cathode gas supply / discharge system 200, an anode gas supply / discharge system 300, and a control device 400.

[0009] The fuel cell 100 generates electricity through an electrochemical reaction between an anode gas and a cathode gas. In this embodiment, the fuel cell 100 is a polymer electrolyte fuel cell, and hydrogen gas is used as the anode gas and air is used as the cathode gas. However, a fuel cell other than a polymer electrolyte fuel cell may be used as the fuel cell 100, and gases other than hydrogen and air may be used as the anode gas and the cathode gas. The fuel cell 100 has a stack structure in which a plurality of unit cells are stacked and connected in series. Each unit cell includes a membrane electrode assembly having electrode catalyst layers on both sides of an electrolyte membrane, and a pair of separators that sandwich the membrane electrode assembly.

[0010] The fuel cell 100 has a cathode gas internal flow path 120 that supplies cathode gas to the cathode side of the membrane electrode assembly of each unit cell, and an anode gas internal flow path 130 that supplies anode gas to the anode side of the membrane electrode assembly of each unit cell. The fuel cell 100 has a cathode gas inlet 121 that introduces cathode gas into the cathode gas internal flow path 120 from outside the fuel cell 100, a cathode gas outlet 122 that discharges cathode off-gas from the cathode gas internal flow path 120 to outside the fuel cell 100, an anode gas inlet 131 that introduces anode gas into the anode gas internal flow path 130 from outside the fuel cell 100, and an anode gas outlet 132 that discharges anode off-gas from the anode gas internal flow path 130 to outside the fuel cell 100. In this disclosure, when the cathode gas inlet 121 and the cathode gas outlet 122 are described without any particular distinction, they are referred to as the cathode gas inlet / outlet, and when the anode gas inlet 131 and the anode gas outlet 132 are described without any particular distinction, they are referred to as the anode gas inlet / outlet.

[0011] The cathode gas supply / discharge system 200 supplies cathode gas to the cathode gas inlet 121 of the fuel cell 100, and discharges the cathode off-gas discharged from the cathode gas outlet 122 to the outside of the fuel cell system 10. In the following description, when there is no need to distinguish between cathode gas and cathode off-gas, they are referred to as cathode gas. In this embodiment, the cathode gas supply / discharge system 200 includes a cathode gas supply passage 211, an air cleaner 212, a compressor 213, a cathode inlet valve 214, a cathode off-gas discharge passage 221, a cathode outlet valve 222, a bypass passage 231, and a bypass valve 232.

[0012] The upstream end of the cathode gas supply channel 211 is connected to the atmosphere, and the downstream end of the cathode gas supply channel 211 is connected to the cathode gas inlet 121 of the fuel cell 100. The cathode gas supply channel 211 is provided with, in this order from the upstream side, an air cleaner 212, a compressor 213, and a cathode inlet valve 214. The air cleaner 212 collects foreign matter in the cathode gas. The compressor 213 pressure-feeds the cathode gas downstream. The cathode inlet valve 214 adjusts the flow rate of the cathode gas supplied to the cathode gas inlet 121. The cathode inlet valve 214 is configured, for example, as an electric valve or a solenoid valve.

[0013] The upstream end of the cathode offgas discharge flow path 221 is connected to the cathode gas outlet 122 of the fuel cell 100, and the downstream end of the cathode offgas discharge flow path 221 is connected to the atmosphere. A cathode outlet valve 222 is provided in the cathode offgas discharge flow path 221. The cathode outlet valve 222 adjusts the flow rate of the cathode offgas discharged from the cathode gas outlet 122. The cathode outlet valve 222 is configured by, for example, an electric valve or a solenoid valve.

[0014] The bypass flow path 231 is a flow path for discharging cathode gas from the cathode gas supply flow path 211 to the cathode off-gas discharge flow path 221 without passing through the fuel cell 100. The upstream end of the bypass flow path 231 is connected to a portion of the cathode gas supply flow path 211 between the compressor 213 and the cathode inlet valve 214, and the downstream end of the bypass flow path 231 is connected to a portion of the cathode off-gas discharge flow path 221 between the cathode outlet valve 222 and the downstream end. The bypass flow path 231 is provided with a bypass valve 232. The bypass valve 232 adjusts the flow rate of the cathode gas passing through the bypass flow path 231. The bypass valve 232 is configured, for example, by an electric valve or a solenoid valve. It is noted that the cathode gas supply / discharge system 200 does not necessarily have to include the bypass flow path 231 and the bypass valve 232.

[0015] The anode gas supply / discharge system 300 supplies anode gas to the anode gas inlet 131 of the fuel cell 100 and discharges anode off-gas discharged from the anode gas outlet 132 of the fuel cell 100 to the outside of the fuel cell system 10. In the following description, when there is no need to distinguish between anode gas and anode off-gas, they will be referred to as anode gas. In this embodiment, the anode gas supply / discharge system 300 includes an anode gas tank 310, an anode gas supply flow path 311, a main stop valve 312, a regulator 313, an anode inlet valve 314, an ejector 315, a pressure sensor 316, an anode off-gas discharge flow path 321, a gas-liquid separator 322, an anode outlet valve 323, and a circulation flow path 331.

[0016] An anode gas tank 310, which serves as an anode gas supply source, stores anode gas pressurized to, for example, 35 MPa or 70 MPa. The upstream end of an anode gas supply channel 311 is connected to the anode gas tank 310, and the downstream end of the anode gas supply channel 311 is connected to the anode gas inlet 131 of the fuel cell 100. The anode gas supply channel 311 is provided with, in this order from the upstream side, a main stop valve 312, a regulator 313, an anode inlet valve 314, an ejector 315, and a pressure sensor 316. The main stop valve 312 adjusts the flow rate of anode gas supplied from the anode gas tank 310. The main stop valve 312 is configured, for example, as an electric valve or a solenoid valve. The regulator 313 reduces the pressure of the anode gas supplied from the main stop valve 312 to the anode inlet valve 314. The anode inlet valve 314 adjusts the flow rate of anode gas supplied to the anode gas inlet 131. The anode inlet valve 314 is configured, for example, by a solenoid valve that injects anode gas. The ejector 315 supplies the anode gas injected from the anode inlet valve 314 to the anode gas inlet 131, and also supplies the anode off-gas sucked from the circulation flow path 331 to the anode gas inlet 131 by utilizing the negative pressure generated by the jet of anode gas. The pressure sensor 316 measures the pressure inside the anode gas supply flow path 311. The opening and closing of the anode inlet valve 314 is controlled based on the pressure measured by the pressure sensor 316.

[0017] The upstream end of the anode off-gas discharge channel 321 is connected to the anode gas outlet 132 of the fuel cell 100, and the downstream end of the anode off-gas discharge channel 321 is connected to a portion of the cathode off-gas discharge channel 221 that is downstream of the connection with the bypass channel 231. The anode off-gas discharge channel 321 is provided with a gas-liquid separator 322 and an anode outlet valve 323, in this order from the upstream side. The gas-liquid separator 322 separates the anode off-gas into gas and liquid components. The anode outlet valve 323 adjusts the flow rates of the gas and liquid components of the anode off-gas discharged from the gas-liquid separator 322 to the cathode off-gas discharge channel 221. The anode outlet valve 323 is configured as an electric valve or a solenoid valve.

[0018] The upstream end of the circulation flow path 331 is connected to the gas-liquid separator 322, and the downstream end of the circulation flow path 331 is connected to the ejector 315. The gas components of the anode off-gas stored in the gas-liquid separator 322 are sucked into the ejector 315 and supplied to the anode gas supply flow path 311 via the circulation flow path 331. Instead of providing the ejector 315 in the anode gas supply / discharge system 300, a pump may be provided that pressure-feeds the gas components of the anode off-gas from the gas-liquid separator 322 to the anode gas supply flow path 311. The anode gas supply / discharge system 300 does not necessarily have to include the circulation flow path 331.

[0019] As shown in FIG. 2, a voltage sensor 12 for measuring the output voltage Vf of the fuel cell 100 is provided at the output terminal of the fuel cell 100. The fuel cell 100 is connected to a fuel cell boost converter 20 via primary side wiring 20a. The fuel cell boost converter 20 is a DC / DC converter that boosts the output voltage Vf of the fuel cell 100. The fuel cell boost converter 20 is connected to an inverter 30 via secondary side wiring 20b. The secondary side wiring 20b is provided with a voltage sensor 23 for measuring the output voltage Vh of the fuel cell boost converter 20. The DC power boosted by the fuel cell boost converter 20 is supplied to the inverter 30. The inverter 30 converts the DC power supplied from the fuel cell 100 and the DC power supplied from the secondary battery 40 into three-phase AC power and supplies it to a motor M1 for driving the compressor 213 shown in FIG. 1 and a motor M2 for driving the wheels of the fuel cell vehicle. In this embodiment, the fuel cell system 10 does not include a relay circuit for electrically connecting or disconnecting the fuel cell 100 and a load. The load is a device that consumes the power of the fuel cell 100, such as motors M1 and M2.

[0020] The secondary battery 40 is a chargeable and dischargeable battery, such as a lithium-ion secondary battery. The secondary battery 40 is electrically connected to a secondary-battery boost converter 60 via primary wiring 60a. The primary wiring 60a is provided with a secondary-battery relay circuit 50 for electrically connecting and disconnecting the secondary battery 40 and the secondary-battery boost converter 60. The primary wiring 60a between the secondary battery 40 and the secondary-battery relay circuit 50 is provided with a voltage sensor 42 for measuring the output voltage Vb of the secondary battery 40. The primary wiring 60a between the secondary battery relay circuit 50 and the secondary-battery boost converter 60 is connected to auxiliary equipment 70 via a boost converter 71, which is a DC / DC converter. In this embodiment, the auxiliary equipment 70 includes multiple auxiliary equipment 70a and 70b. The multiple auxiliary equipment 70a and 70b include, for example, a cooling water pump for circulating cooling water for cooling the fuel cell 100. The secondary battery boost converter 60 is a DC / DC converter that boosts the output voltage Vb of the secondary battery 40. The secondary battery boost converter 60 is connected to secondary side wiring 20b between the fuel cell boost converter 20 and the inverter 30 via secondary side wiring 60b. The circuit group from the secondary battery 40 to the secondary battery boost converter 60 is connected in parallel to the circuit group from the fuel cell 100 to the fuel cell boost converter 20. The DC power boosted by the secondary battery boost converter 60 is supplied to the inverter 30. The secondary battery boost converter 60 can also step down the power of the fuel cell 100 and the regenerative power of the motor M2 to charge the secondary battery 40.

[0021] In the fuel cell system 10, the high-voltage circuit including the fuel cell 100, the high-voltage circuit including the secondary battery 40, and the motors M1 and M2 are insulated from an external conductor provided outside the fuel cell system 10. Specifically, the external conductor is the body of the fuel cell vehicle. Ideally, insulation resistance has an infinite resistance value. However, for example, damage to the insulating coating of the wiring can cause the insulation resistance to decrease. The insulation resistance Ri shown in Figure 2 represents the insulation resistance between the positive electrode side of the circuit in the FC area and the external conductor. The FC area refers to the group of circuits from the fuel cell 100 to the fuel cell boost converter 20. In Figure 2, insulation resistances other than the insulation resistance Ri are not shown.

[0022] 3, the control device 400 is configured by a computer including a processor 401, a memory 402, an input / output interface 403, and an internal bus 404. The processor 401, the memory 402, and the input / output interface 403 are connected via the internal bus 404 to enable bidirectional communication. The input / output interface 403 is connected via wired or wireless communication to the compressor 213, various valves including the cathode inlet valve 214, the cathode outlet valve 222, the bypass valve 232, the main stop valve 312, the anode inlet valve 314, and the anode outlet valve 323, and various sensors including a pressure sensor 316 and an atmospheric pressure sensor 340. The atmospheric pressure sensor 340 measures the atmospheric pressure around the fuel cell system 10. Although not shown in the figure, the input / output interface 403 is further connected to voltage sensors 12, 23, 42, a boost converter 20 for a fuel cell, an inverter 30, a boost converter 60 for a secondary battery, etc. via wired or wireless communication.

[0023] The processor 401 executes a computer program PG pre-stored in the memory 402 to perform various functions, including a function to control the operation of the fuel cell 100 and a function to diagnose the sealing state of the cathode gas inlet / outlet and anode gas inlet / outlet of the fuel cell 100. Note that at least some of the functions of the control device 400 may be realized by a hardware circuit.

[0024] In this disclosure, stopping the supply of cathode gas and anode gas to the fuel cell 100 to stop power generation by the fuel cell 100 is referred to as stopping the fuel cell 100, and restarting the supply of cathode gas and anode gas to the fuel cell 100 to restart power generation by the fuel cell 100 is referred to as restarting the fuel cell 100. If air flows into the anode gas internal flow path 130 while the fuel cell 100 is stopped, the anode-side electrode catalyst layer may deteriorate when the fuel cell 100 is restarted. If the anode inlet / outlet is not properly sealed, air may flow into the anode gas internal flow path 130 from the anode inlet / outlet. If the cathode inlet / outlet is not properly sealed, air that flows into the cathode gas internal flow path 120 from the cathode inlet / outlet may permeate the electrolyte membrane and flow into the anode gas internal flow path 130. Therefore, it is preferable that the cathode gas inlet / outlet and anode gas inlet / outlet of the fuel cell 100 be properly sealed while the fuel cell 100 is stopped.

[0025] 4 is a flowchart showing the steps of a diagnostic method for diagnosing the sealing state of the cathode gas inlet / outlet and the anode gas inlet / outlet of the fuel cell 100. This diagnostic method is started when the fuel cell 100 is shut down. In this embodiment, this diagnostic method is executed by the processor 401 of the control device 400. Note that at least a part of this diagnostic method may also be executed by a person.

[0026] In step S110, before shutting down the fuel cell 100, the processor 401 supplies anode gas to the anode gas internal flow passage 130 of the fuel cell 100, thereby pressurizing the anode gas internal flow passage 130 to a predetermined target pressure. In this embodiment, the processor 401 pressurizes the anode gas internal flow passage 130 to the target pressure by supplying anode gas from the anode gas tank 310 to the anode gas internal flow passage 130 while the anode outlet valve 323 is closed. The target pressure is set to a pressure higher than the atmospheric pressure surrounding the fuel cell system 10. The target pressure is set so that the internal pressures of the cathode gas internal flow passage 120 and the anode gas internal flow passage 130 are sufficiently higher than atmospheric pressure when the cathode gas inlet / outlet and the anode gas inlet / outlet are well sealed and an equilibrium state is reached between the internal pressures of the cathode gas internal flow passage 120 and the anode gas internal flow passage 130. The target pressure can be determined, for example, based on the results of a test performed in advance.

[0027] In step S120, the processor 401 seals the cathode gas inlet and outlet and the anode gas inlet and outlet of the fuel cell 100. In this disclosure, sealing the cathode gas inlet and outlet means preventing the cathode gas internal flow channel 120 from communicating with the atmosphere through the cathode gas inlet and outlet, and sealing the anode gas inlet and outlet means preventing the anode gas internal flow channel 130 from communicating with the atmosphere through the anode gas inlet and outlet. In this embodiment, the processor 401 closes the cathode inlet valve 214 to seal the cathode gas inlet 121, closes the cathode outlet valve 222 to seal the cathode gas outlet 122, and closes the anode outlet valve 323 to seal the anode gas inlet 131 and the anode gas outlet 132. In addition, the processor 401 closes the main stop valve 312 and the anode inlet valve 314 to prevent anode gas from being supplied from the anode gas tank 310 to the anode gas inlet 131. The processor 401 keeps the cathode gas inlet / outlet and the anode gas inlet / outlet sealed from the time the fuel cell 100 is stopped until it is restarted. In other words, the processor 401 keeps the cathode gas inlet / outlet and the anode gas inlet / outlet sealed while the fuel cell 100 is stopped. In this embodiment, the fuel cell system 10 does not include a relay circuit that electrically disconnects the fuel cell 100 from the load. Therefore, power generation by the fuel cell 100 can continue until at least one of the cathode gas remaining in the cathode gas internal flow path 120 and the anode gas remaining in the anode gas internal flow path 130 is consumed. However, when at least one of the cathode gas remaining in the cathode gas internal flow path 120 and the anode gas remaining in the anode gas internal flow path 130 is consumed, power generation by the fuel cell 100 stops.

[0028] In step S130, the processor 401 determines whether or not to restart the fuel cell 100. The processor 401 repeats the process of step S130 until it is determined that the fuel cell 100 should be restarted.

[0029] If it is determined in step S130 that the fuel cell 100 is to be restarted, the processor 401 acquires the internal pressure of the anode gas internal passage 130 in step S140. In this embodiment, the processor 401 acquires the pressure measured by the pressure sensor 316 as the internal pressure of the anode gas internal passage 130. Because the pressure sensor 316 is disposed near the anode gas inlet 131, the pressure measured by the pressure sensor 316 can be used as the internal pressure of the anode gas internal passage 130. In the following description, the pressure measured by the pressure sensor 316 will be referred to as the pressure sensor value. The pressure sensor value may be expressed as an absolute pressure or a gauge pressure.

[0030] In step S150, the processor 401 compares the pressure sensor value with the atmospheric pressure and determines whether the pressure sensor value is higher than the atmospheric pressure. In this embodiment, the processor 401 acquires the atmospheric pressure measured by the atmospheric pressure sensor 340 and compares the pressure sensor value with the atmospheric pressure measured by the atmospheric pressure sensor 340. If it is determined in step S150 that the pressure sensor value is higher than the atmospheric pressure, the processor 401 determines in step S160 that the sealing state of the cathode gas inlet / outlet and the anode gas inlet / outlet is good. If it is determined in step S150 that the pressure sensor value is not higher than the atmospheric pressure, the processor 401 determines in step S170 that the sealing state of the cathode gas inlet / outlet and the anode gas inlet / outlet is poor. After step S160 or step S170, the processor 401 ends this process. In this embodiment, if it is determined that the sealing condition of the cathode gas inlet / outlet and the anode gas inlet / outlet is good, the processor 401 restarts the fuel cell 100, and if it is determined that the sealing condition of the cathode gas inlet / outlet and the anode gas inlet / outlet is poor, the processor 401 aborts the restart of the fuel cell 100 without restarting it.

[0031] FIG. 5 is an explanatory diagram showing the internal pressure of the fuel cell 100 when the cathode gas inlet / outlet and the anode gas inlet / outlet of the fuel cell 100 are properly sealed. FIG. 6 is an explanatory diagram showing the internal pressure of the fuel cell 100 when the cathode gas inlet / outlet and the anode gas inlet / outlet of the fuel cell 100 are poorly sealed. FIGS. 5 and 6 show the internal pressures of the cathode gas internal flow path 120 and the anode gas internal flow path 130 immediately after the fuel cell 100 is shut down, as well as the internal pressures of the cathode gas internal flow path 120 and the anode gas internal flow path 130 in an equilibrium state. As shown in FIGS. 5 and 6, immediately after the fuel cell 100 is shut down, the internal pressure of the anode gas internal flow path 130 is higher than atmospheric pressure due to the supply of anode gas from the anode gas tank 310 before the fuel cell 100 is shut down. In contrast, the internal pressure on the cathode gas internal flow path 120 side is approximately the same as atmospheric pressure due to the compressor 213 being shut down.

[0032] 5, when the cathode gas inlet / outlet and the anode gas inlet / outlet are well sealed, the oxygen in the air sealed in the cathode gas internal flow path 120 and the hydrogen sealed in the anode gas internal flow path 130 are consumed while the fuel cell 100 is stopped, causing the oxygen partial pressure in the cathode gas internal flow path 120 and the hydrogen partial pressure in the anode gas internal flow path 130 to decrease. After a sufficient amount of time has passed, all of the oxygen in the cathode gas internal flow path 120 is consumed. Some of the hydrogen remaining in the anode gas internal flow path 130 permeates the electrolyte membrane and flows into the cathode gas internal flow path 120, and some of the nitrogen remaining in the cathode gas internal flow path 120 permeates the electrolyte membrane and flows into the anode gas internal flow path 130. As a result, in an equilibrium state, hydrogen and nitrogen remain in the cathode gas internal flow channel 120 and the anode gas internal flow channel 130, and the internal pressure of the cathode gas internal flow channel 120 and the internal pressure of the anode gas internal flow channel 130 are higher than atmospheric pressure.

[0033] As shown in FIG. 6 , for example, if at least one of the cathode inlet valve 214 and the cathode outlet valve 222 fails to close, or if the sealing material of at least one of the cathode inlet valve 214 and the cathode outlet valve 222 deteriorates, the cathode gas inlet / outlet becomes poorly sealed, and the cathode gas internal flow path 120 is connected to the atmosphere. In this case, even if the oxygen sealed in the cathode gas internal flow path 120 is consumed, oxygen from the atmosphere is supplied to the cathode gas internal flow path 120. After a sufficient amount of time has passed, all of the hydrogen in the anode gas internal flow path 130 is consumed. Some of the air in the cathode gas internal flow path 120 permeates the electrolyte membrane and flows into the anode gas internal flow path 130. As a result, in an equilibrium state, oxygen and nitrogen remain in the cathode gas internal flow path 120 and the anode gas internal flow path 130, and the internal pressures of the cathode gas internal flow path 120 and the anode gas internal flow path 130 are equal to atmospheric pressure.

[0034] According to the fuel cell system 10 of the present embodiment described above, the processor 401 of the control device 400 pressurizes the anode gas internal flow passage 130 to a target pressure higher than atmospheric pressure by supplying anode gas to the anode gas internal flow passage 130 of the fuel cell 100 before shutting down the fuel cell 100, seals the cathode gas inlet / outlet and anode gas inlet / outlet of the fuel cell 100 while the fuel cell 100 is shut down, and determines whether the cathode gas inlet / outlet and anode gas inlet / outlet are properly sealed by comparing the internal pressure of the anode gas internal flow passage 130 with atmospheric pressure before restarting the fuel cell 100. Therefore, the sealing state of the cathode gas inlet / outlet and anode gas inlet / outlet of the fuel cell 100 can be accurately and easily diagnosed.

[0035] Furthermore, in this embodiment, the target pressure is set so that the internal pressure of the cathode gas internal flow channel 120 and the internal pressure of the anode gas internal flow channel 130 are higher than atmospheric pressure when the sealing state of the cathode gas inlet / outlet and the anode gas inlet / outlet is good and the internal pressure of the cathode gas internal flow channel 120 and the internal pressure of the anode gas internal flow channel 130 are in equilibrium. This makes it possible to prevent the sealing state from being erroneously determined to be poor when it is actually good.

[0036] Furthermore, in this embodiment, the sealing state of the cathode gas inlet / outlet and the anode gas inlet / outlet can be diagnosed by comparing the pressure measured by the pressure sensor 316 used in the operation of the fuel cell 100 with atmospheric pressure, so that the sealing state of the cathode gas inlet / outlet and the anode gas inlet / outlet can be diagnosed without using other sensors such as a concentration sensor, a flow rate sensor, a temperature sensor, etc. Therefore, an increase in the number of parts of the fuel cell system 10 can be suppressed.

[0037] B. Other Embodiments: (B1) In the fuel cell system 10 of the first embodiment described above, the pressure sensor 316 is provided in a portion of the anode gas supply flow path 311 between the ejector 315 and the anode gas inlet 131. Alternatively, the pressure sensor 316 may be provided in a portion of the anode off-gas discharge flow path 321 between the anode gas outlet 132 and the gas-liquid separator 322.

[0038] (B2) In the fuel cell system 10 of the first embodiment described above, the processor 401 of the control device 400 determines whether the cathode gas inlet / outlet and the anode gas inlet / outlet are properly sealed by comparing the pressure measured by the pressure sensor 316 with the atmospheric pressure measured by the atmospheric pressure sensor 340. However, the fuel cell system 10 does not need to be provided with the atmospheric pressure sensor 340. For example, the processor 401 may obtain weather information from outside the fuel cell system 10 using a communication device or the like, and determine whether the cathode gas inlet / outlet and the anode gas inlet / outlet are properly sealed by comparing the pressure measured by the pressure sensor 316 with the atmospheric pressure included in the weather information. In this case, the fuel cell system 10 does not need to be provided with the atmospheric pressure sensor 340.

[0039] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0040] 10... fuel cell system, 20... fuel cell boost converter, 30... inverter, 40... secondary battery, 50... secondary battery relay circuit, 60... secondary battery boost converter, 70... auxiliary equipment, 100... fuel cell, 120... cathode gas internal flow path, 121... cathode gas inlet, 122... cathode gas outlet, 130... anode gas internal flow path, 131... anode gas inlet, 132... anode gas outlet, 200... cathode gas supply / exhaust system, 211... cathode gas supply flow path, 212... air cleaner, 213... compressor, 214... cathode inlet valve, 221... cathode off-gas gas discharge flow path, 222...cathode outlet valve, 231...bypass flow path, 232...bypass valve, 300...anode gas supply and discharge system, 310...anode gas tank, 311...anode gas supply flow path, 312...main stop valve, 313...regulator, 314...anode inlet valve, 315...ejector, 316...pressure sensor, 321...anode off-gas discharge flow path, 322...gas-liquid separator, 323...anode outlet valve, 331...circulation flow path, 340...atmospheric pressure sensor, 400...control device, 401...processor, 402...memory, 403...input / output interface, 404...internal bus

Claims

1. A method for diagnosing a sealing state of a fuel cell, comprising: before the fuel cell is stopped, an anode gas is supplied to the fuel cell to pressurize the inside of the fuel cell to a predetermined pressure higher than atmospheric pressure; While the fuel cell is stopped, the anode gas inlet and outlet and the cathode gas inlet and outlet of the fuel cell are kept sealed, and determining whether the sealing state is good or bad by comparing the internal pressure of the fuel cell measured before restarting the fuel cell with atmospheric pressure; Diagnostic methods.

2. The diagnostic method according to claim 1, the predetermined pressure is a pressure at which the pressure in the cathode gas internal flow path and the pressure in the anode gas internal flow path become higher than atmospheric pressure when the sealing state is good and an equilibrium state is reached in which the pressure in the cathode gas internal flow path and the pressure in the anode gas internal flow path provided inside the fuel cell are balanced, If the internal pressure of the fuel cell measured before restarting the fuel cell is higher than atmospheric pressure, the sealing state is determined to be good; The diagnostic method determines that the sealing state is poor if the internal pressure of the fuel cell measured before restarting the fuel cell is not higher than atmospheric pressure.

3. 1. A fuel cell system, comprising: A fuel cell; an anode gas supply source that supplies an anode gas to the fuel cell; a plurality of valves for sealing the anode gas inlet and outlet and the cathode gas inlet and outlet of the fuel cell; a pressure sensor for measuring the pressure inside the fuel cell; a control device for controlling the plurality of valves; Equipped with The control device before the fuel cell is stopped, an anode gas is supplied from the anode gas supply source to the fuel cell, thereby pressurizing the inside of the fuel cell to a predetermined pressure higher than atmospheric pressure; When the fuel cell is stopped, the plurality of valves are closed to maintain a sealed state in which the anode gas inlet and outlet and the cathode gas inlet and outlet of the fuel cell are sealed; determining whether the sealing state is good or bad by comparing the internal pressure of the fuel cell measured using the pressure sensor with atmospheric pressure before restarting the fuel cell; Fuel cell system.

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