Fuel Cell Systems

Abstract

To provide a technique for preventing a large amount of fuel gas from staying in a fuel cell (FC) stack when a pass / fail inspection of a main stop valve is performed.SOLUTION: A FC system disclosed in the present specification includes a main stop valve that stops the outflow of fuel gas from a fuel tank, an injector that adjusts a flow rate of the fuel gas supplied to a FC stack, a fuel pipe that connects the main stop valve and the injector, a compressor that blows air to the FC stack, an exhaust gas pipe in which the fuel gas in the FC stack is mixed with the air to be discharged, an exhaust valve that closes the gas pipe, and a controller. The controller opens / closes the injector after opening / closing the main stop valve, and opens the exhaust valve when an inner pressure of the FC stack reaches a predetermined threshold while performing a main stop valve inspection for determining the pass / fail of the main stop valve based on a pressure change in the fuel pipe and drives the compressor such that a concentration of fuel discharged from the exhaust pipe becomes equal to or less than a predetermined upper limit concentration.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a fuel cell system. [Background technology]

[0002] The fuel cell system includes a main stop valve and an injector between the fuel cell stack and the fuel tank. For convenience of explanation, the gas flow path between the main stop valve and the injector is referred to as the high-pressure flow path. Patent Document 1 discloses a technique for checking the quality of the main stop valve. In this specification, a defective main stop valve means that the main stop valve does not close completely even when a command to close the main stop valve is sent, causing fuel gas to leak from the fuel tank to the high-pressure flow path.

[0003] The main stop valve checking process disclosed in Patent Document 1 is as follows: Close the injector and open the main stop valve. When the gas pressure in the high-pressure line reaches a predetermined first pressure, close the main stop valve. Next, open the injector. When the gas pressure in the high-pressure line drops to a second pressure, close the injector. Wait for a fixed period of time with both the injector and the main stop valve closed. If the gas pressure in the high-pressure line exceeds "second pressure + allowable pressure differential" after the fixed period of time, it is determined that the main stop valve is not completely closed.

[0004] For ease of explanation, checking whether the main stop valve closes completely will be referred to as a main stop valve inspection below. Also, for ease of explanation, "fuel cell" will sometimes be written as "FC." "Fuel cell system" will sometimes be written as "FC system," and "fuel cell stack" will sometimes be written as "FC stack." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-149321 A Summary of the Invention [Problem to be solved by the invention]

[0006] When checking the quality of the main stop valve, the injector is opened, causing fuel gas to flow into the FC stack before startup. As the scale of the FC system increases, the volume of the high-pressure flow path also increases. If the volume of the high-pressure flow path is large, a large amount of fuel gas flows into the FC stack during the quality check. If a large amount of fuel gas flows into the FC stack before startup, the following problems may occur: (1) The internal pressure of the FC stack becomes excessively high. (2) In the FC stack before startup, a large amount of fuel gas leaks from the anode to the cathode. This specification provides technology that prevents a large amount of fuel gas from remaining in the FC stack during a main stop valve inspection. [Means for solving the problem]

[0007] The FC system disclosed in this specification includes a fuel tank, an FC stack, a main stop valve, an injector, a fuel pipe, a compressor, an exhaust pipe, an exhaust valve, and a controller. The main stop valve stops the outflow of fuel gas from the fuel tank. The injector adjusts the flow rate of fuel gas supplied to the FC stack. The fuel pipe connects the main stop valve to the injector. The compressor sends air to the FC stack. The exhaust pipe mixes the fuel gas in the FC stack with air and releases it. The exhaust valve closes the exhaust pipe. The controller controls the main stop valve, the injector, the compressor, and the exhaust valve. The controller performs a main stop valve inspection (opening and closing the main stop valve, then opening and closing the injector, and judging whether the main stop valve is good or bad based on the pressure change in the fuel pipe). While performing the main stop valve inspection, the controller opens the exhaust valve when the internal pressure of the FC stack reaches a predetermined threshold pressure, and drives the compressor so that the concentration of fuel released from the exhaust pipe is equal to or lower than a predetermined upper limit concentration.

[0008] The fuel cell system disclosed in this specification prevents a large amount of fuel gas from accumulating in the FC stack during a main stop valve inspection. In addition, the controller controls the compressor so that the fuel concentration in the exhaust gas does not exceed the upper limit concentration. Gas containing a high concentration of fuel is not discharged.

[0009] The FC system disclosed in this specification is also preferably equipped with a bypass flow path that sends air from the compressor to the exhaust gas pipe, bypassing the FC stack. The controller may use the bypass flow path to send air from the compressor to the exhaust gas pipe while performing a main stop valve inspection. This can prevent the inside of the FC stack from drying out excessively before start-up.

[0010] An example of a procedure for inspecting the main stop valve is as follows: The controller closes the injector and opens the main stop valve to increase the internal pressure of the fuel line to a first pressure, then closes the main stop valve and opens the injector to decrease the internal pressure. The controller identifies the amount of fuel gas injected by the injector while the internal pressure of the fuel line is decreasing. If the amount of fuel gas injected exceeds a predetermined injection amount threshold before the internal pressure of the fuel line decreases to a second pressure, the controller determines that the main stop valve is defective.

[0011] In the main stop valve inspection method of Patent Document 1 mentioned above, after the internal pressure of the fuel pipe is lowered to the second pressure, a fixed time is waited, and if the pressure has dropped after the fixed time has elapsed, it is determined that the main stop valve is defective. With this method, it takes time to determine whether the main stop valve is good or bad. In the FC system disclosed in this specification, the quality of the main stop valve is determined based on the injection amount of the injector and the pressure change in the fuel pipe. This makes it possible to shorten the time required for main stop valve inspection.

[0012] Details and further improvements of the technology disclosed in this specification are described in the following "Forms for Carrying Out the Invention". [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram of an FC system according to an embodiment. [Diagram 2] 4 is a flowchart of a main stop valve inspection process. [Diagram 3] 4 is a flowchart of a main stop valve inspection process (continuation of FIG. 2). [Figure 4] 13 is a flowchart of an FC stack internal pressure monitoring process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An FC system 2 according to an embodiment will be described with reference to the drawings. FIG. 1 shows a block diagram of the FC system 2. The FC system 2 comprises an FC stack 3, multiple fuel tanks 4a, 4b, and a compressor 9. Fuel (hydrogen) is stored in the fuel tanks 4a, 4b. The FC system 2 generates electricity by reacting the fuel in the fuel tanks 4a, 4b with oxygen in the air. Gaseous fuel (i.e., fuel gas) is sent from the fuel tanks 4a, 4b to the FC stack 3, and the compressor 9 supplies air to the FC stack 3.

[0015] Each of the multiple fuel tanks 4a, 4b is connected to the FC stack 3 by a fuel pipe 7. The fuel pipe 7 is equipped with main stop valves 5a, 5b and an injector 6. The main stop valves 5a, 5b are arranged on the upstream side of the fuel pipe 7 (the side closest to the fuel tanks 4a, 4b) and stop the outflow of fuel gas from the fuel tanks 4a, 4b. When the FC stack 3 is stopped, the main stop valves 5a, 5b are closed, ensuring the safety of the FC system 2.

[0016] The injector 6 is placed on the downstream side of the fuel pipe 7 (the side closest to the FC stack 3) and adjusts the flow rate of fuel gas supplied to the FC stack 3. Note that a gas regulator may be installed between the injector 6 and the main stop valves 5a, 5b. In that case, the flow rate of fuel gas supplied to the FC stack 3 is adjusted by the injector 6 and the gas regulator. However, it is the injector 6 that ultimately adjusts the flow rate of fuel gas supplied to the FC stack 3.

[0017] Fuel pipe 7 connects fuel tanks 4a, 4b to FC stack 3, but for ease of explanation, the portion of fuel pipe 7 connecting main stop valves 5a, 5b to injector 6 will be referred to as high-pressure fuel pipe 7a, and the portion connecting FC stack 3 to injector 6 will be referred to as low-pressure fuel pipe 7b.

[0018] A gas-liquid separator 15 is connected to the fuel gas outlet of the FC stack 3. The gas-liquid separator 15 separates unreacted fuel gas from the gas discharged from the fuel gas outlet. The separated fuel gas is returned to the low-pressure fuel pipe 7b via a return path 16 and is reused. A pump 14 is provided in the return path 16, and the pump 14 forcibly returns the unreacted fuel gas to the low-pressure fuel pipe 7b.

[0019] An exhaust gas pipe 17 is connected to the gas outlet of the gas-liquid separator 15, and a muffler 20 is attached to the middle of the exhaust gas pipe 17. The impurities separated by the gas-liquid separator 15 are discharged to the outside through the exhaust gas pipe 17 and the muffler 20. Air is also sent from the compressor 9 through an exhaust air pipe 19 to the muffler 20. A small amount of fuel gas remains in the impurities separated by the gas-liquid separator 15. The controller 10 estimates the concentration of fuel in the exhaust gas discharged to the outside from the muffler 20, and air is sent from the compressor 9 so that the estimated concentration value of the fuel contained in the exhaust gas is equal to or lower than a predetermined upper limit concentration. Since the concentration estimation can be performed using conventional technology, a description of the concentration estimation will be omitted. The concentration may be measured by a concentration sensor. Hereinafter, the estimated concentration value of the fuel contained in the exhaust gas is simply referred to as the "fuel concentration".

[0020] An exhaust gas valve 18 is attached to the exhaust gas pipe 17. The exhaust gas valve 18 closes the exhaust gas pipe 17 to stop exhaust gas from escaping to the outside.

[0021] The compressor 9 and FC stack 3 are connected by an air pipe 12. The air pipe 12 and exhaust air pipe 19 are connected by a bypass flow path 11. An air supply valve 23 is attached to the air pipe 12, and an air exhaust valve 24 is attached to the exhaust air outlet of the FC stack 3. A bypass valve 13 is attached to the bypass flow path 11. When the bypass valve 13 is closed, the air supply valve 23 is opened, and the compressor 9 is driven, outside air is sent to the FC stack 3. When the FC stack 3 is driven, the air exhaust valve 24 is also opened. When the air supply valve 23 and air exhaust valve 24 are closed, the bypass valve 13 is opened, and the compressor 9 is driven, outside air bypasses the FC stack 3 from the compressor 9 and is sent to the exhaust gas pipe 17 via the exhaust air pipe 19.

[0022] The flow paths are equipped with pressure sensors 31a and 31b, and the FC stack 3 is equipped with a temperature sensor 32. The pressure sensor 31a measures the internal pressure of the high-pressure fuel pipe 7a. The pressure sensor 31b measures the internal pressure of the low-pressure fuel pipe 7b. The measurement values ​​of the pressure sensors 31a, 31b and the temperature sensor 32 are sent to the controller 10. The FC system 2 is equipped with several other pressure sensors and temperature sensors, but illustration and description of these are omitted.

[0023] The controller 10 controls the main stop valves 5a, 5b, the injector 6, various valves (main stop valves 5a, 5b, air supply valve 23, air exhaust valve 24, bypass valve 13, exhaust gas valve 18), compressor 9, and pump 14. Based on an output command from a higher-level controller (not shown), the controller 10 adjusts the flow rate of fuel gas and the flow rate of air supplied to the FC stack 3 so that the FC stack 3 outputs a specified amount of power. The controller 10 adjusts the flow rate of fuel gas supplied to the FC stack 3 by controlling the injector 6, and adjusts the amount of air supplied to the FC stack 3 by controlling the compressor 9.

[0024] In the FC system 2, the main stop valves 5a, 5b are checked for quality before starting up the FC stack 3. Alternatively, the main stop valves 5a, 5b are checked for quality when shutting down the FC stack 3. The main stop valves 5a, 5b are solenoid-type valves that open and close in response to commands from the controller 10. A defect in the main stop valves 5a, 5b means that the main stop valves 5a, 5b do not close completely despite a command to close being sent from the controller 10 to the main stop valves 5a, 5b, causing fuel gas in the fuel tanks 4a, 4b to leak through the main stop valves 5a, 5b into the high-pressure fuel pipe 7a.

[0025] As mentioned above, the process for determining whether the main stop valves 5a, 5b are good or bad is hereinafter referred to as the main stop valve inspection process. The main stop valve inspection process is outlined as follows. The controller 10 opens and closes the main stop valves 5a, 5b while keeping the injector 6 closed, and then opens and closes the injector 6 while keeping the main stop valves 5a, 5b closed. The controller 10 determines whether the main stop valves 5a, 5b are good or bad based on the change in internal pressure of the high-pressure fuel pipe 7a between the opening and closing of the injector 6 and the opening and closing of the main stop valves 5a, 5b. The specific steps of the main stop valve inspection process will be explained using Figures 2-4.

[0026] 2 and 3 are flowcharts of the main stop valve inspection process, and Fig. 4 is a flowchart of the FC stack internal pressure monitoring process that is executed simultaneously in parallel with the main stop valve inspection process.

[0027] First, the controller 10 starts the FC stack internal pressure monitoring process (step S2). The FC stack internal pressure monitoring process will be described later. Next, the controller 10 closes the injector 6 and opens the main stop valves 5a, 5b (step S3). When the main stop valves 5a, 5b are opened, fuel gas flows from the fuel tanks 4a, 4b to the high-pressure fuel pipe 7a. The controller 10 monitors the measurement value of the pressure sensor 31a (i.e., the internal pressure of the high-pressure fuel pipe 7a), and closes the main stop valves 5a, 5b when the internal pressure of the high-pressure fuel pipe 7a reaches a predetermined first pressure (steps S4: YES, S5).

[0028] To be precise, "closing the main stop valve" in step S5 of FIG. 2 means that the controller 10 sends a closing command to the main stop valve. If the main stop valves 5a and 5b are normal, the main stop valves 5a and 5b will close completely in response to the closing command from the controller 10, and the fuel tanks 4a and 4b and the high-pressure fuel pipe 7a will be completely blocked. However, if the main stop valves 5a and / or 5b do not close completely even though the controller 10 sends a closing command, fuel gas will continue to leak from the fuel tanks 4a and / or 4b to the high-pressure fuel pipe 7a. The processing in FIGS. 2 and 3 is processing for detecting such a closing failure of the main stop valves 5a and / or 5b.

[0029] Next, the controller 10 opens the injector 6 (FIG. 3, step S12). When the injector 6 is opened, the fuel gas in the high-pressure fuel pipe 7a flows to the low-pressure fuel pipe 7b. The controller 10 calculates the volume (injection amount) of the fuel gas injected by the injector 6 (step S13). The flow rate (volume of fuel gas injected per unit time) injected by the injector 6 depends on the temperature and pressure. The relationship between the flow rate and the temperature / pressure is known. The measurement value of the temperature sensor 32 provided in the FC stack 3 can be used as an approximate temperature of the injected fuel gas. The gas pressure in the injector 6 is estimated from the measurement values ​​of the pressure sensors 31a and 31b arranged upstream and downstream of the injector 6. The controller 10 obtains the gas pressure upstream of the injector 6 from the measurement value of the pressure sensor 31a attached to the high-pressure fuel pipe 7a, and obtains the gas pressure downstream of the injector 6 from the measurement value of the pressure sensor 31b attached to the low-pressure fuel pipe 7b. The controller 10 estimates the gas pressure that correlates with the flow rate of the injector 6 from the gas pressures upstream and downstream of the injector 6. A description of the estimation of the gas pressure will be omitted. The flow rate of the injector 6 is obtained from the measurement values ​​of the temperature sensor 32 and the pressure sensors 31a and 31b. Note that the sensor measurement values ​​used to obtain the flow rate of the injector 6 are not limited to the above example. For example, if a flow rate sensor is provided upstream or downstream of the injector 6, the measurement value of the flow rate sensor can be used as the flow rate of the injector 6 as is.

[0030] The controller 10 repeatedly calculates the volume (injection amount) of the fuel gas injected from the injector 6 while the injector 6 is open (steps S15, NO, S13). The injection amount is calculated from the time from when the injector 6 is opened and the flow rate of the injector 6. If the injection amount exceeds a predetermined injection amount threshold before the internal pressure of the high-pressure fuel pipe 7a drops to the second pressure, the controller 10 determines that at least one of the main stop valves 5a, 5b is defective (step S14: NO). In other words, if the injection amount exceeds a predetermined injection amount threshold before the internal pressure of the high-pressure fuel pipe 7a drops to the second pressure, the controller 10 determines that at least one of the main stop valves 5a, 5b is defective.

[0031] The first pressure and the second pressure are determined in advance. The second pressure is set to a value lower than the first pressure. The injection amount threshold is set to a gas volume required to reduce the internal pressure of the high-pressure fuel pipe 7a from the first pressure to the second pressure. Therefore, if the internal pressure of the high-pressure fuel pipe 7a drops to the second pressure before the injection amount of the injector 6 exceeds the injection amount threshold, the controller 10 determines that the main stop valves 5a, 5b are normal (step S14: NO, S15: YES). In this case, the controller 10 notifies the upper controller (not shown) that the main stop valves 5a, 5b are normal (step S16). Then, the controller 10 closes the injector 6 (step S18), ends the FC stack internal pressure monitoring process (step S19), and ends the main stop valve inspection process.

[0032] On the other hand, when the injection amount of the injector 6 exceeds the injection amount threshold, it is found that at least one of the main stop valves 5a, 5b is not completely closed and fuel gas is leaking from the fuel tanks 4a, 4b to the high-pressure fuel pipe 7a. That is, the controller 10 judges that at least one of the main stop valves 5a, 5b is defectively closed. In this case, the controller 10 notifies a higher-level controller (not shown) of the defect of the main stop valves 5a, 5b (step S17). If a defect of the main stop valve 5a or 5b is detected, the controller 10 closes the injector 6 even if the internal pressure does not drop to the second pressure (step S18). After closing the injector 6, the controller 10 ends the FC stack internal pressure monitoring process (step S19) and ends the main stop valve inspection process.

[0033] When the main stop valve inspection process is ended via step S16, the upper controller executes the next normal process. When the main stop valve inspection process is performed before starting up the FC stack 3, if the main stop valve is normal, the upper controller next executes startup process for the FC stack 3. When the main stop valve inspection process is performed before stopping the FC stack, if the main stop valve is normal, the upper controller next executes process to stop the FC stack 3.

[0034] On the other hand, when the main stop valve inspection process is ended via step S17, the upper controller executes a process corresponding to a main stop valve malfunction (anomaly response process). When a malfunction of the main stop valve 5a or 5b is detected, the upper controller displays a message indicating the main stop valve malfunction, for example, on a display device of the FC system 2. Alternatively, the upper controller turns on a warning lamp of the FC system 2.

[0035] 2 and 3, a check is made to see whether the main stop valves 5a, 5b are completely closed in response to a closing command from the controller 10.

[0036] Next, the FC stack internal pressure monitoring process will be described with reference to Fig. 4. The process in Fig. 4 is repeatedly executed during the main stop valve inspection process. More precisely, the process in Fig. 4 is repeatedly executed while the injector 6 is open in the main stop valve inspection process.

[0037] The controller 10 acquires the internal pressure of the FC stack 3 (step S22). Since the low-pressure fuel pipe 7b is directly connected to the FC stack 3, the measurement value of the pressure sensor 31b that measures the internal pressure of the low-pressure fuel pipe 7b is used as the internal pressure of the FC stack 3.

[0038] The controller 10 compares the internal pressure of the FC stack 3 with a predetermined threshold pressure (step S23). The threshold pressure is set to the upper limit of the pressure range suitable for starting the FC stack 3. The internal pressure of the FC stack 3 starts to rise at the same time as opening the injector 6 in step S12 of FIG. 3. When the internal pressure of the FC stack 3 reaches the threshold pressure (step S23: YES), the controller 10 executes the processes of steps S24 and S25. That is, the controller 10 opens the exhaust gas valve 18 (step S24) and drives the compressor 9 so that the concentration of fuel contained in the exhaust gas released to the outside air is equal to or lower than the upper limit concentration (step S25).

[0039] During the FC stack internal pressure monitoring process, the controller 10 closes the air supply valve 23 and air exhaust valve 24, and keeps the bypass valve 13 open. Because the bypass valve 13 is open, air is sent from the compressor 9 via the bypass flow path 11 to the exhaust gas pipe 17. Part of the fuel gas from the FC stack 3 flows through the exhaust gas pipe 17 via the gas-liquid separator 15. The fuel gas discharged from the FC stack 3 is mixed with air in the muffler 20 attached midway through the exhaust gas pipe 17, and is released into the outside air.

[0040] In step S25, the controller 10 drives the compressor 9 so that the fuel concentration contained in the exhaust gas discharged to the outside air is equal to or lower than a predetermined upper limit concentration. Increasing the output of the compressor 9 increases the amount of air supplied to the muffler 20, and the fuel concentration decreases. This control prevents exhaust gas containing fuel with a concentration exceeding a specified value (upper limit concentration) from being discharged.

[0041] If it is determined in step S23 that the internal pressure of the FC stack 3 does not exceed the threshold pressure, the controller 10 ends the process without opening the exhaust gas valve 18 or driving the compressor 9 (steps S23: NO, S26). As described above, the controller 10 repeatedly executes the process of FIG.

[0042] The advantages of the main stop valve inspection in the FC system 2 of the embodiment will be described. During main stop valve inspection processing, the controller 10 opens the exhaust gas valve 18 when the internal pressure of the FC stack 3 reaches a threshold pressure. At the same time, the controller 10 drives the compressor 9 so that the concentration of fuel released from the exhaust gas pipe 17 is equal to or lower than the upper limit concentration. The former process prevents a large amount of fuel gas from remaining in the FC stack 3 during the main stop valve inspection. The latter process prevents exhaust gas containing a high concentration of fuel from being released to the outside during the main stop valve inspection.

[0043] As the scale of the FC system 2 increases (as the number of fuel tanks connected to the FC stack increases), the capacity of the high-pressure fuel pipe 7a increases. As the capacity of the high-pressure fuel pipe 7a increases, the amount of fuel gas that flows into the FC stack 3 during main stop valve inspection increases. The main stop valve inspection process in the FC system 2 of the embodiment is suitable for such a large-scale FC system.

[0044] In the main stop valve inspection process of the embodiment, the quality of the main stop valve is judged based on the internal pressure of the high pressure fuel pipe 7a and the injection amount while the injector 6 is open. Since it is based on the injection amount of the injector 6, the quality of the main stop valve is judged in a short time. The process of the embodiment can judge the quality of the main stop valve in a short time.

[0045] In the FC system 2 of the embodiment, fuel gas is released during the main stop valve inspection process when the internal pressure of the FC stack 3 exceeds the threshold pressure. This prevents the internal pressure of the FC stack 3 from rising excessively. Furthermore, when the fuel gas remaining in the FC stack 3 is released, the controller 10 and compressor 9 work to dilute the fuel so that the fuel concentration is equal to or lower than the upper limit concentration. Furthermore, air for diluting the fuel is sent from the compressor 9 to the exhaust gas pipe 17, bypassing the FC stack 3. Since excessive air is not sent to the FC stack 3, it is also possible to prevent the FC stack 3 from drying out.

[0046] Points to note regarding the technology described in the embodiment are described below. The high pressure fuel pipe 7a corresponds to the fuel pipe connecting the main stop valves 5a, 5b and the injector 6. In the embodiment, the main stop valves 5a, 5b are opened and closed simultaneously. One main stop valve may be opened and closed while the other main stop valve is kept closed to execute the processes of Figs. 2 to 4, and then one main stop valve may be opened and closed while the other main stop valve is kept closed to execute the processes of Figs. 2 to 4. The quality of multiple main stop valves can be determined individually. The number of fuel tanks (main stop valves) connected to the injector may be three or more. The FC system may also be configured to have one main stop valve for multiple fuel tanks.

[0047] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives is itself technically useful. [Explanation of symbols]

[0048] 2: FC system 3: FC stack 4a, 4b: Fuel tank 5a, 5b: Main stop valve 6: Injector 7: Fuel pipe 7a: High-pressure fuel pipe 7b: Low-pressure fuel pipe 9: Compressor 10: Controller 11: Bypass flow path 12: Air pipe 13: Bypass valve 14: Pump 15: Gas-liquid separator 16: Return flow path 17: Exhaust gas pipe 18: Exhaust gas valve 19: Exhaust air pipe 20: Muffler 23: Air supply valve 24: Air exhaust valve 31a, 31b: Pressure sensor 32: Temperature sensor

Claims

1. A fuel tank; A fuel cell stack; a main stop valve for stopping the outflow of fuel gas from the fuel tank; an injector for adjusting a flow rate of the fuel gas supplied to the fuel cell stack; a fuel pipe connecting the main stop valve and the injector; a compressor for delivering air to the fuel cell stack; an exhaust gas pipe that mixes the fuel gas in the fuel cell stack with the air and discharges the mixture; an exhaust gas valve for closing the exhaust gas pipe; a controller that controls the main stop valve, the injector, the compressor, and the exhaust gas valve; It is equipped with The controller opens and closes the injector after opening and closing the main stop valve, and while performing a main stop valve inspection to determine whether the main stop valve is good or bad based on pressure changes in the fuel pipe, opens the exhaust gas valve when the internal pressure of the fuel cell stack reaches a predetermined threshold pressure, and drives the compressor so that the concentration of fuel released from the exhaust gas pipe is below a predetermined upper limit concentration.

2. The controller, in the main stop valve inspection, closing the injector and opening the main stop valve to raise the internal pressure of the fuel pipe to a first pressure, then closing the main stop valve and opening the injector, and if the amount of fuel gas injected by the injector exceeds a predetermined injection amount threshold before the internal pressure of the fuel pipe drops to a second pressure, it is determined that the main stop valve is defective. The fuel cell system according to claim 1 .

3. 3. The fuel cell system of claim 1, further comprising a bypass flow path that sends the air from the compressor to the exhaust gas pipe, bypassing the fuel cell stack, and the controller uses the bypass flow path to send the air from the compressor to the exhaust gas pipe while performing the main stop valve inspection.

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