Fuel cell system
The fuel cell system addresses valve abnormality detection by using a pressure sensor and control device to compare pressure drop rates, ensuring accurate valve operation and preventing leaks, especially in sub-zero conditions.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-04-11
- Publication Date
- 2026-05-11
AI Technical Summary
Existing fuel cell systems face difficulties in determining abnormalities in the opening and closing of exhaust valves, particularly when both an exhaust drain valve and an exhaust valve are present, and there is a challenge in defining a normal range for the pressure drop rate of low-pressure anode off-gas during fuel cell power generation.
A fuel cell system with a pressure sensor in the anode gas circulation path, a first valve for exhaust, and a second valve connected to a gas-liquid separator, uses a control device to determine abnormalities by comparing pressure drop rates when each valve is operated independently.
The system can accurately identify abnormal opening and closing of both valves, preventing anode gas leaks and ensuring proper valve operation, especially in sub-zero conditions, thereby maintaining fuel cell stack integrity and preventing deterioration.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a fuel cell system.
Background Art
[0002] Conventionally, fuel cell systems have been known. The fuel cell system described in Patent Document 1 below includes a fuel cell, an anode gas supply system, an anode gas circulation system, a cathode gas supply / discharge system, an exhaust and drainage passage, an exhaust and drainage valve for opening and closing the exhaust and drainage passage, a flow rate acquisition unit, and a control unit.
[0003] In the fuel cell system described in this Patent Document 1, when the control unit is in a state of giving an open valve instruction to the exhaust and drainage valve, the control unit executes the normal abnormality determination of the opening of the exhaust and drainage valve as follows. When the exhaust flow rate of the anode gas is equal to or greater than a predetermined normal reference value, the control unit determines that the exhaust and drainage valve is normally open, and when the exhaust flow rate is lower than the normal reference value, the control unit determines that the exhaust and drainage valve is not normally open.
[0004] Further, the fuel cell system described in Patent Document 2 below includes a fuel cell, an oxidant gas supply pipe through which oxidant gas flows into the fuel cell, and an oxidant off-gas discharge pipe through which oxidant off-gas from the fuel cell flows. Further, this conventional fuel cell system includes a pressure regulating valve provided in the oxidant off-gas discharge pipe for adjusting the pressure of the oxidant gas in the fuel cell, a gas-liquid separator provided in the oxidant off-gas discharge pipe for separating liquid water from the oxidant off-gas, and an exhaust and drainage valve that serves both for exhaust and drainage from the liquid reservoir of the gas-liquid separator.
[0005] Furthermore, the fuel cell system described in Patent Document 2 includes a pressure sensor for measuring the pressure of the oxidizer gas in the fuel cell and an ECU. The ECU controls the pressure regulating valve to a predetermined opening degree so that the pressure of the oxidizer gas in the fuel cell reaches a target pressure. Subsequently, the ECU performs pressure control to adjust the opening degree of the pressure regulating valve so that the pressure based on the measured value measured by the pressure sensor reaches the target pressure, and determines that there is an abnormal opening or closing of the exhaust drain valve if the adjustment range of the opening degree of the pressure regulating valve in the pressure control is greater than a predetermined value. [Prior art documents] [Patent Documents]
[0006] [Patent Document 1] Japanese Patent Publication No. 2020-017435 [Patent Document 2] Japanese Patent Publication No. 2022-132887 [Overview of the Initiative] [Problems that the invention aims to solve]
[0007] In the fuel cell system described in Patent Document 2, if the exhaust drain valve malfunctions during operation and remains open, anode off-gas will leak. However, it is difficult to define a normal range for the rate of pressure drop of low-pressure anode off-gas during fuel cell power generation. Furthermore, while the fuel cell system described in Patent Document 1 can detect abnormalities in the opening of the exhaust drain valve, if both an exhaust drain valve and an exhaust valve are provided, it may not be possible to determine which valve is malfunctioning.
[0008] This disclosure provides a fuel cell system capable of determining abnormalities in the opening and closing of an exhaust valve and an exhaust valve. [Means for solving the problem]
[0009] One aspect of the present disclosure is a fuel cell system comprising: a pressure sensor provided in an anode gas circulation path that circulates anode off-gas discharged from a fuel cell stack back to the fuel cell stack; a first valve that opens and closes an exhaust path branching off from the anode gas circulation path; a second valve connected to a gas-liquid separator provided in the anode gas circulation path and, when opened, discharges gas and liquid from the gas-liquid separator to an exhaust drainage path; and a control device that determines opening and closing abnormalities of the first valve and the second valve, wherein the control device determines opening and closing abnormalities of the first valve or the second valve based on a comparison between a first pressure decrease rate, which is the rate at which the pressure detected by the pressure sensor decreases when a first control is performed to open the first valve with the second valve closed, and a second pressure decrease rate, which is the rate at which the pressure detected by the pressure sensor decreases when a second control is performed to open the second valve with the first valve closed. [Effects of the Invention]
[0010] According to one aspect of the present disclosure, a fuel cell system can be provided that can determine abnormal opening and closing of a first valve as an exhaust valve and a second valve as an exhaust drain valve. [Brief explanation of the drawing]
[0011] [Figure 1] A process flow diagram showing one embodiment of the fuel cell system relating to this disclosure. [Figure 2] A flowchart showing the processing of the control unit of the fuel cell system in Figure 1. [Figure 3] A time chart showing the pressure detection values and the open / closed state of each valve during each process in Figure 2. [Figure 4] A flowchart showing another process of the control device for the fuel cell system in Figure 1. [Figure 5] A time chart showing the pressure detection values and the open / closed state of each valve during each process in Figure 4. [Modes for carrying out the invention]
[0012] Hereinafter, embodiments of the fuel cell system according to this disclosure will be described with reference to the drawings.
[0013] Figure 1 is a process flow diagram showing one embodiment of a fuel cell system according to the present disclosure. The fuel cell system 100 of this embodiment is mounted on a vehicle such as a fuel cell vehicle and supplies power to an on-board device including an electric motor for driving. The fuel cell system 100 of this embodiment includes, for example, a fuel cell stack 110, an anode gas supply system 120, a cathode gas supply system 130, an anode gas circulation system 140, and a gas-liquid discharge system 150. The fuel cell system 100 also includes, for example, a cooling water circulation system (not shown) and a control device.
[0014] The fuel cell stack 110 has, for example, a configuration in which multiple solid oxide fuel cell single cells are stacked, and has an anode gas inlet 111, an anode off-gas outlet 112, a cathode gas inlet 113, and a cathode off-gas outlet 114. The fuel cell stack 110 also has, for example, a cooling water inlet and a cooling water outlet (not shown).
[0015] The anode gas supply system 120 includes, for example, an anode gas supply passage 121 connected to a high-pressure tank (not shown) via a pressure reducing valve, and an injector 122, and supplies hydrogen gas as anode gas to the fuel cell stack 110. The control device of the fuel cell system 100 can control the pressure of the low-pressure anode gas flowing downstream of the injector 122 by, for example, controlling the injector 122.
[0016] The cathode gas supply system 130 includes, for example, a cathode gas supply passage 131 connected to an air cleaner (not shown), a compressor 132, an intercooler 133, a flow divider valve 134, a sealing valve 135, and a pressure regulating valve 136. The cathode gas supply system 130 compresses the air supplied as cathode gas through the cathode gas supply passage 131 using the compressor 132, cools it using the intercooler 133, and supplies it to the cathode gas inlet 113 of the fuel cell stack 110 through the sealing valve 135.
[0017] The anode gas circulation system 140 includes, for example, an anode gas circulation path 141, a gas-liquid separator 142, a first valve 143 as an exhaust valve, a hydrogen pump 144, a pressure sensor 145, and a second valve 146 as an exhaust and drainage valve. The anode gas circulation path 141 is, for example, a flow path connecting the anode off-gas outlet 112 and the anode gas inlet 111 of the fuel cell stack 110, and circulates the anode off-gas discharged from the fuel cell stack 110 back to the fuel cell stack 110.
[0018] The gas-liquid separator 142 is provided, for example, in the anode gas circulation path 141, and separates liquids such as water contained in the anode off-gas flowing through the anode gas circulation path 141 from the anode off-gas. The second valve 146 as an exhaust and drainage valve is connected to the gas-liquid separator 142, for example, and discharges the gas-liquid from the gas-liquid separator 142 to the exhaust and drainage path 151 of the gas-liquid discharge system 150 when the valve is opened. The hydrogen pump 144 is provided, for example, in the anode gas circulation path 141, and pumps the anode off-gas discharged from the anode off-gas outlet 112 of the fuel cell stack 110 to the anode gas inlet 111.
[0019] The pressure sensor 145 is provided, for example, in the anode gas supply path 121 or the anode gas circulation path 141 downstream of the injector 122, and detects the pressure of the low-pressure anode gas including the anode off-gas supplied to the anode gas inlet 111 of the fuel cell stack 110. The first valve 143 as an exhaust valve that discharges the anode gas including the anode off-gas from the anode gas circulation path 141 opens and closes an exhaust path 152 that branches from the anode gas circulation path 141 and is connected to the discharge path 154 of the gas-liquid discharge system 150. The first valve 143 and the second valve 146 have, for example, equal inner diameters or substantially equal pressure losses with respect to the anode gas.
[0020] The gas-liquid discharge system 150 includes, for example, an exhaust and drainage path 151, an exhaust path 152, and a shunt path 153 and an exhaust passage 154. The exhaust and drainage passage 151 connects, for example, the outlet of the second valve 146 connected to the gas-liquid separator 142 and the exhaust passage 154. The exhaust passage 152 branches from, for example, the anode gas circulation passage 141 and is connected to the exhaust passage 154. The shunt passage 153 connects, for example, the outlet of the shunt valve 134 and the exhaust passage 154. The exhaust passage 154 connects, for example, the outlet of the pressure regulating valve 136 and a muffler (not shown).
[0021] Figure 2 is a flowchart showing the processing of the control device of the fuel cell system 100 in FIG. 1. Figure 3 is a time chart showing the pressure detection value of the pressure sensor 145 and the open / closed states of the first valve 143 and the second valve 146 in each process of FIG. 2. The control device of the fuel cell system 100 determines, for example, the opening / closing abnormalities of the first valve 143 as the exhaust valve shown in FIG. 1 and the second valve 146 as the exhaust and drainage valve by executing each process shown in FIG. 2. Hereinafter, each process shown in FIG. 2 will be described in detail.
[0022] When the vehicle equipped with the fuel cell system 100 stops at normal temperature or after warm-up and the start switch is turned off, the control device of the fuel cell system 100 starts the processing flow shown in FIG. 2 and executes the system termination process P101. As a result, for example, as shown in FIG. 3, the system termination process flag changes from OFF to ON, and the termination process P101 of the fuel cell system 100 is started.
[0023] Next, the control device of the fuel cell system 100 executes, for example, the anode gas replacement process P102. In this process P102, the control device of the fuel cell system 100 controls, for example, the injector 122 to increase the pressure of the anode gas supplied to the fuel cell stack 110. As a result, as shown in FIG. 3, the pressure detection value of the pressure sensor 145 increases to a predetermined pressure P1, for example, between time t1 and time t2.
[0024] Next, the control device of the fuel cell system 100 performs, for example, a first control (process P103). The first control is, for example, opening the first valve 143, which acts as an exhaust valve, while closing the second valve 146, which acts as an exhaust drain valve. Simultaneously with the start of this first control, the control device of the fuel cell system 100 starts process P104 to measure the first pressure drop rate PDR1. In this process P104, the control device of the fuel cell system 100 stores time-series data of the pressure detection value in memory, for example, until the pressure detection value by the pressure sensor 145 drops to a predetermined pressure P0.
[0025] Process P103 causes anode gas to be discharged from the anode gas circulation path 141 through the first valve 143, which acts as an exhaust valve. As shown in Figure 3, the pressure detected by the pressure sensor 145 decreases from pressure P1 to a predetermined pressure P0 between time t2 and time t3. Process P104 also allows the control device of the fuel cell system 100 to measure the first pressure decrease rate PDR1, which is the rate at which the pressure detected value decreases when the first control is executed.
[0026] Next, the control device of the fuel cell system 100 performs, for example, a second anode gas replacement process P105. In this process P105, the control device of the fuel cell system 100 closes both the first valve 143 and the second valve 146, similar to the first anode gas replacement process P102 described above, to increase the pressure of the anode gas in the anode gas circulation path 141. As a result, for example, as shown in Figure 3, the pressure detected by the pressure sensor 145 rises to a predetermined pressure P1 between time t3 and time t4.
[0027] Next, the control device of the fuel cell system 100 performs, for example, a second control (process P106). The second control is, for example, a control that opens the second valve 146, which acts as an exhaust drain valve, while closing the first valve 143, which acts as an exhaust valve. Simultaneously with the start of this second control, the control device of the fuel cell system 100 starts a process P107 to measure the second pressure drop rate PDR2, similar to the process P104 described above for measuring the first pressure drop rate PDR1.
[0028] Process P106 causes anode gas to be discharged from the anode gas circulation path 141 through the second valve 146, which acts as an exhaust drain valve. As shown in Figure 3, between time t4 and time t5, the pressure detected by the pressure sensor 145 decreases from pressure P1 to a predetermined pressure P0. Process P107 also allows the control device of the fuel cell system 100 to measure the second pressure decrease rate PDR2, which is the rate at which the pressure detected value decreases when the second control is executed.
[0029] Next, the control device of the fuel cell system 100 performs, for example, at least one of the first determination process P108 and the second determination process P109. In the example shown in Figure 3, the first pressure drop rate PDR1 of the pressure detected by the pressure sensor 145 measured between time t2 and time t3 is lower than the second pressure drop rate PDR2 of the pressure detected by the pressure sensor 145 measured between time t4 and time t5.
[0030] In this case, in the first determination process P108, the control device of the fuel cell system 100 determines, for example, that the first pressure drop rate PDR1 is lower than the second pressure drop rate PDR2 (YES). In this case, the control device of the fuel cell system 100 executes process P111, which determines a first valve closure abnormality that hinders the opening operation of the first valve 143 as an exhaust valve, and terminates the processing flow shown in Figure 2.
[0031] On the other hand, in the first determination process P108 described above, if the control device of the fuel cell system 100 determines, for example, that the first pressure drop rate PDR1 is not lower than the second pressure drop rate PDR2 (NO), it executes the second determination process P109. In this second determination process P109, if the control device of the fuel cell system 100 determines, for example, that the second pressure drop rate PDR2 is not lower than the first pressure drop rate PDR1 (NO), it performs a normal determination of the first valve 143 and the second valve 146 (process P110) and terminates the processing flow shown in Figure 2.
[0032] Furthermore, in the aforementioned second determination process P109, if the control device of the fuel cell system 100 determines, for example, that the second pressure drop rate PDR2 is lower than the first pressure drop rate PDR1 (YES), it executes process P112 to determine a second valve closure abnormality that hinders the opening operation of the second valve 146 as an exhaust drain valve, and terminates the processing flow shown in Figure 2.
[0033] Figure 4 is a flowchart showing another process of the control device of the fuel cell system 100 shown in Figure 1. Figure 5 is a time chart showing the pressure detected by the pressure sensor 145 and the open / closed states of the first valve 143 and the second valve 146 in each process in Figure 4. When the control device of the fuel cell system 100 starts the process flow shown in Figure 4, for example, while the fuel cell system 100 is in operation, it first performs a third control that closes both the first valve 143 and the second valve 146 (process P201).
[0034] Next, the control device of the fuel cell system 100 performs, for example, a process P202 to measure the third pressure drop rate PDR3 when the above third control is performed, and a leak determination process P203. In the leak determination process P203, the control device of the fuel cell system 100 determines whether the third pressure drop rate PDR3 satisfies the leak condition based on a comparison of the third pressure drop rate PDR3 with a predetermined value of the pressure drop rate PDRt.
[0035] Here, the predetermined value PDRt for the pressure drop rate is, for example, the pressure drop rate when the pressure detected by the pressure sensor 145 decreases from a predetermined pressure P2 to a predetermined pressure P3 between time t0 and time t1, as shown by the dashed line in Figure 5. The predetermined value PDRt for the pressure drop rate can be estimated, for example, based on the amount of anode gas consumed by the fuel cell stack 110 due to power generation and the amount of anode gas consumed due to cross-leakage.
[0036] The amount of anode gas consumed by the fuel cell stack 110 due to power generation is estimated, for example, by calculating the amount of anode gas consumed by the chemical reaction based on the detected value of the current sensor that detects the power generation current of the fuel cell stack 110. In addition, the amount of anode gas consumed due to cross-leakage can be determined, for example, from the hardware characteristics of the fuel cell cells that make up the fuel cell stack 110.
[0037] In this leak detection process P203, the control device of the fuel cell system 100 determines that the leak condition is not met (NO) if, for example, the third pressure drop rate PDR3 is not higher than a predetermined value PDRt of the pressure drop rate. After that, the control device of the fuel cell system 100 terminates the processing flow shown in Figure 4.
[0038] On the other hand, the control device of the fuel cell system 100 determines, for example, as shown in Figure 5, that if the third pressure drop rate PDR3 is higher than a predetermined value PDRt of the pressure drop rate, the leak condition is met (YES), indicating that a leak is occurring from the anode gas circulation path 141. Subsequently, the control device of the fuel cell system 100 executes processes P204 to P209, which are the same as processes P102 to P107 in the processing flow shown in Figure 2 above.
[0039] Next, the control device of the fuel cell system 100 performs, for example, at least one of the third determination process P210 and the fourth determination process P211. In the example shown in Figure 5, the second pressure drop rate PDR2 of the pressure detected by the pressure sensor 145 measured between time t4 and time t5 is higher than the first pressure drop rate PDR1 of the pressure detected by the pressure sensor 145 measured between time t2 and time t3.
[0040] In this case, in the third determination process P210, the control device of the fuel cell system 100 determines, for example, that the second pressure drop rate PDR2 is higher than the first pressure drop rate PDR1 (YES), and executes process P212 to determine a first valve opening abnormality that impedes the closing operation of the first valve 143 as an exhaust valve. That is, if the second pressure drop rate PDR2 is higher than the first pressure drop rate PDR1, the first valve 143, which should be closed, may not close sufficiently, and anode gas may be leaking from the first valve 143. After that, the control device of the fuel cell system 100 terminates the processing flow shown in Figure 4.
[0041] On the other hand, in the third determination process P210 described above, if the control device of the fuel cell system 100 determines, for example, that the second pressure drop rate PDR2 is not higher than the first pressure drop rate PDR1 (NO), it executes the fourth determination process P211. In this fourth determination process P211, if the control device of the fuel cell system 100 determines, for example, that the first pressure drop rate PDR1 is not higher than the second pressure drop rate PDR2 (NO), it terminates the processing flow shown in Figure 4.
[0042] On the other hand, in the aforementioned fourth determination process P211, if the control device of the fuel cell system 100 determines, for example, that the first pressure drop rate PDR1 is higher than the second pressure drop rate PDR2 (YES), it executes process P213 to determine a second valve opening abnormality that impedes the closing operation of the second valve 146, which acts as an exhaust drain valve. That is, if the first pressure drop rate PDR1 is higher than the second pressure drop rate PDR2, the second valve 146, which should be closed, may not close sufficiently, and anode gas may be leaking from the second valve 146. After that, the control device of the fuel cell system 100 terminates the processing flow shown in Figure 4.
[0043] Furthermore, in order to ensure consistent conditions in process P206 for measuring the first pressure drop rate PDR1 and process P209 for measuring the second pressure drop rate PDR2, the detected values of the pressure sensor 145 after the completion of anode gas replacement processes P204 and P207 are made identical. In addition, to suppress the influence of anode gas consumption due to power generation by the fuel cell stack 110, processes P204 to P209 are performed, for example, when the fuel cell stack 110 is generating the same current. Alternatively, the amount of anode gas consumed by power generation by the fuel cell stack 110 from processes P204 to P209 may be calculated, and the first pressure drop rate PDR1 and the second pressure drop rate PDR2 may be corrected in processes P206 and P209.
[0044] As described above, the fuel cell system 100 of this embodiment includes a pressure sensor 145, a first valve 143 as an exhaust valve, a second valve 146 as an exhaust drain valve, and a control device for determining abnormal opening and closing of the first valve 143 and the second valve 146. The pressure sensor 145 is provided in the anode gas circulation path 141 that circulates the anode off gas discharged from the fuel cell stack 110 back to the fuel cell stack 110. The first valve 143 opens and closes the exhaust path 152 that branches off from the anode gas circulation path 141. The second valve 146 is connected to a gas-liquid separator 142 provided in the anode gas circulation path 141 and discharges gas and liquid from the gas-liquid separator 142 to the exhaust drain path 151 when the valve is open. The control device of the fuel cell system 100 of this embodiment determines abnormal opening and closing of the first valve 143 or the second valve 146 based on a comparison of the first pressure drop rate PDR1 and the second pressure drop rate PDR2. The first pressure drop rate PDR1 is the rate at which the pressure detected by the pressure sensor 145 decreases when the first control is performed, in which the first valve 143, which acts as an exhaust valve, is opened while the second valve 146, which acts as an exhaust and drain valve, is closed. The second pressure drop rate PDR2 is the rate at which the pressure detected by the pressure sensor 145 decreases when the second control is performed, in which the second valve 146, which acts as an exhaust and drain valve, is opened while the first valve 143, which acts as an exhaust valve, is closed.
[0045] With this configuration, the fuel cell system 100 of this embodiment can determine abnormalities in the opening and closing of the first valve 143 and the second valve 146 by the control device, based on a comparison between the first pressure drop rate PDR1 when only the first valve 143 is open and the second pressure drop rate PDR2 when only the second valve 146 is open.
[0046] Furthermore, as shown in Figure 2, the control device of the fuel cell system 100 in this embodiment determines a first valve closure abnormality that hinders the opening operation of the first valve 143 when the first pressure drop rate PDR1 is lower than the second pressure drop rate PDR2. Also, as shown in Figure 2, the control device of the fuel cell system 100 in this embodiment determines a second valve closure abnormality that hinders the opening operation of the second valve 146 when the second pressure drop rate PDR2 is lower than the first pressure drop rate PDR1.
[0047] With this configuration, for example, if a vehicle becomes unable to start in sub-zero temperatures, it is possible to distinguish between a component failure and a first valve closure abnormality and a second valve closure abnormality, where freezing impedes the opening operation of the first valve 143 and the second valve 146, respectively. This eliminates the closure abnormality of the first valve 143, which acts as an exhaust valve used for anode gas replacement during sub-zero starting of the vehicle, enabling anode gas replacement during sub-zero starting and preventing deterioration of the fuel cell stack 110.
[0048] Furthermore, the control device of the fuel cell system 100 in this embodiment measures, for example, the first pressure drop rate PDR1 and the second pressure drop rate PDR2 during system termination processing. In this case, there is no consumption of anode gas due to power generation by the fuel cell stack 110, and the rate of decrease of the pressure detected by the pressure sensor 145 can be measured with high accuracy. In addition, by performing the processes P104 and P107 for measuring the first pressure drop rate PDR1 and the second pressure drop rate PDR2 together with the normally performed anode gas replacement processes P102 and P105, unnecessary consumption of anode gas can be suppressed.
[0049] Furthermore, the control device of the fuel cell system 100 of this embodiment determines whether a leak condition is met, for example, when the third pressure drop rate PDR3, which is the rate at which the pressure detected by the pressure sensor 145 decreases when a third control is executed to close both the first valve 143 and the second valve 146, is higher than a predetermined value PDRt. Also, if the above leak condition is met and the second pressure drop rate PDR2 is higher than the first pressure drop rate PDR1, the control device of the fuel cell system 100 of this embodiment determines a first valve opening abnormality that hinders the closing operation of the first valve 143 as an exhaust valve. Also, if the above leak condition is met and the first pressure drop rate PDR1 is higher than the second pressure drop rate PDR2, the control device of the fuel cell system 100 of this embodiment determines a second valve opening abnormality that hinders the closing operation of the second valve 146 as an exhaust drain valve.
[0050] With this configuration, for example, in the fuel cell system 100 of this embodiment, if the anode gas circulation path 141 satisfies the leak condition, the control device can determine that the first valve 143 or the second valve 146 is abnormally open.
[0051] As described above, according to this embodiment, it is possible to provide a fuel cell system 100 that can determine abnormal opening and closing of the first valve 143 as an exhaust valve and the second valve 146 as an exhaust drain valve.
[0052] While embodiments of the fuel cell system relating to this disclosure have been described in detail above using drawings, the specific configuration is not limited to these embodiments, and any design changes, etc., that do not depart from the gist of this disclosure are also included in this disclosure. [Explanation of Symbols]
[0053] 100 Fuel Cell Systems 110 Fuel Cell Stack 141 Anode Gas Circulation Path 142 Gas-liquid separator 143 First valve 145 Pressure Sensor 146 Second valve 151 Exhaust and drainage channel 152 Exhaust passage PDR1 First pressure drop rate PDR2 Second Pressure Drop Rate PDR3 Third Pressure Drop Rate PDRt prescribed value
Claims
1. The system comprises a pressure sensor provided in an anode gas circulation path that circulates anode off-gas discharged from the fuel cell stack back to the fuel cell stack, a first valve that opens and closes an exhaust path branching off from the anode gas circulation path, a second valve connected to a gas-liquid separator provided in the anode gas circulation path and, when open, discharges gas and liquid from the gas-liquid separator to an exhaust drainage path, and a control device that determines abnormalities in the opening and closing of the first and second valves. The fuel cell system is characterized in that the control device determines an abnormal opening or closing of the first valve or the second valve based on a comparison between a first pressure decrease rate, which is the rate at which the pressure detected by the pressure sensor decreases when a first control is performed to open the first valve while the second valve is closed, and a second pressure decrease rate, which is the rate at which the pressure detected by the pressure sensor decreases when a second control is performed to open the second valve while the first valve is closed.
2. The control device is When the first pressure drop rate is lower than the second pressure drop rate, a first valve closure abnormality that impedes the opening operation of the first valve is determined. The fuel cell system according to claim 1, characterized in that when the second pressure drop rate is lower than the first pressure drop rate, a second valve closure abnormality that impedes the opening operation of the second valve is determined.
3. The control device is When the third control is performed to close both the first valve and the second valve, it is determined whether the third pressure decrease rate, which is the rate at which the pressure detected by the pressure sensor decreases, satisfies a leak condition where the pressure decreases above a predetermined value. When the aforementioned leak condition is met and the second pressure drop rate is higher than the first pressure drop rate, a first valve opening abnormality that impedes the closing operation of the first valve is determined. The fuel cell system according to claim 1, characterized in that when the leak condition is met and the first pressure drop rate is higher than the second pressure drop rate, a second valve opening abnormality that impedes the closing operation of the second valve is determined.