Fuel cell system

Abstract

The present invention relates to a fuel cell system. When an ECU (100) of a fuel cell system (10) receives a signal related to stopping power generation of a fuel cell stack (12) during operation of a mobile body (11), the ECU (100) determines whether temperature information exceeds a temperature threshold (Tt) for determination. When the temperature information exceeds the temperature threshold (Tt) for determination, the ECU (100) performs a stop control to stop power generation of the fuel cell stack (12). On the other hand, when the temperature information is below the temperature threshold (Tt) for determination, the ECU (100) performs an idle speed control to cause the fuel cell stack (12) to generate power at a power consumption less than that of an air pump (68).

Description

Technical Field

[0001] The present invention relates to a fuel cell system which is installed in a mobile body and generates electricity while the mobile body is running. Background Art

[0002] When the fuel cell system mounted on a mobile body such as a fuel cell vehicle stops operating (power generation stops) and the surrounding environment is low temperature and freezing occurs in the system, power generation immediately after the start of operation will be delayed. Therefore, the applicant has proposed the following technology, as shown in Patent Document 1, which monitors the temperature in the system during shutdown and performs freeze suppression control when freezing is predicted. In the freeze suppression control, the fuel cell system operates the air pump that supplies the cathode gas and opens the sealing valve of the cathode path. As a result, the cathode gas flows in the cathode path and the moisture in the cathode path is discharged to the outside.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent JP2017-147022A Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, the fuel cell system may sometimes receive a request to stop the fuel cell stack from generating electricity during the operation of the mobile body. When the cathode gas is circulated to the fuel cell stack each time a request to stop generating electricity is received during the operation of the mobile body, the electrolyte membrane of the internal power generation cell will deteriorate. As a result, the durability of the fuel cell stack will rapidly decrease over a long period of time.

[0008] On the other hand, if the sealing valve of the cathode path is closed to stop power generation of the fuel cell stack every time a request to stop power generation is received, the sealing valve may freeze in the closed state if the surrounding environment is low temperature.

[0009] An object of the present invention is to provide a fuel cell system that can appropriately prevent freezing from occurring in the system and suppress degradation of an electrolyte membrane even when power generation is stopped during operation of a mobile body.

[0010] Solutions for solving problems

[0011] In order to achieve the above-mentioned purpose, one embodiment of the present invention relates to a fuel cell system, which is arranged on a mobile body, and the fuel cell system includes: a fuel cell stack; a cathode supply path, which supplies cathode gas to the fuel cell stack; a cathode exhaust path, which exhausts cathode exhaust from the fuel cell stack; a bypass path, which connects the cathode supply path to the cathode exhaust path in a manner that bypasses the fuel cell stack; an air pump, which supplies the cathode gas to the cathode supply path; one or more sealing valves, wherein the one or more sealing valves are arranged between a connection portion of the cathode supply path connected to the bypass path and the fuel cell stack, or between a connection portion of the cathode exhaust path connected to the bypass path and the fuel cell stack; a bypass valve, which is arranged in the bypass path; and a control device, which controls the air pump, one or more sealing valves, The control device controls the operation of the sealing valve and the bypass valve, the control device obtains temperature information related to the temperature of the fuel cell stack from a temperature detection unit provided in the fuel cell system, and when the control device receives a signal related to the cessation of power generation of the fuel cell stack during the operation of the mobile body, the control device determines whether the obtained temperature information exceeds a predetermined temperature value, and when the control device determines that the temperature information exceeds the predetermined temperature value, the control device closes one or more of the sealing valves and opens the bypass valve, thereby performing a first control to stop the power generation of the fuel cell stack, and when the control device determines that the temperature information is below the predetermined temperature value, the control device operates the air pump, thereby performing a second control to enable the fuel cell stack to generate power with a power smaller than the power consumption of the air pump.

[0012] Effects of the Invention

[0013] The above-described fuel cell system can appropriately prevent freezing from occurring in the system and suppress degradation of the electrolyte membrane even when power generation stops during operation of the mobile body.

[0014] The following embodiments will be described with reference to the accompanying drawings, and the above-mentioned objects, features, and advantages will be easily understood based on the description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is an explanatory diagram schematically showing the overall structure of a fuel cell system according to one embodiment of the present invention.

[0016] Figure 2 It is a block diagram of the ECU of the fuel cell system.

[0017] Figure 3A It is an explanatory diagram schematically showing the flow state of the cathode gas during the stop control.

[0018] Figure 3BThis is a timing chart illustrating the operation of each component in the stop control.

[0019] Figure 4A It is an explanatory diagram schematically showing the flow state of cathode gas during idle control.

[0020] Figure 4B This is a timing chart illustrating the operation of each component in the idle speed control.

[0021] Figure 5 This is a flowchart illustrating the processing of the ECU when receiving a power generation stop signal during operation of the mobile body.

[0022] Figure 6 This is a flowchart illustrating the processing of the ECU during stop control.

[0023] Figure 7 This is a flowchart illustrating the processing of the ECU in the idle speed control.

[0024] Fig. 8A This is a flowchart illustrating the processing of the ECU during the stop control according to the modification.

[0025] Figure 8B This is a flowchart illustrating the processing of the ECU in the idle speed control according to another modification. DETAILED DESCRIPTION

[0026] like Figure 1 As shown, a fuel cell system 10 according to one embodiment of the present invention includes a fuel cell stack 12, an anode system device 14, a cathode system device 16, and a cooling device 18. The fuel cell system 10 is mounted on a mobile body 11 such as a fuel cell vehicle. The fuel cell system 10 supplies the generated power of the fuel cell stack 12 to a battery Bt, a driving motor Mt, etc. Moreover, the mobile body 11 equipped with the fuel cell system 10 is not limited to a fuel cell vehicle, but may also be other vehicles, ships, aircraft, robots, etc.

[0027] The fuel cell stack 12 contains a stack body 21 formed by stacking a plurality of power generation cells 20 in a stack case (not shown). Each power generation cell 20 generates electricity through an electrochemical reaction between an anode gas (fuel gas such as hydrogen) and a cathode gas (oxidant gas such as air).

[0028] Each power generation cell 20 is composed of an electrolyte membrane-electrode assembly 22 (hereinafter referred to as "MEA 22") and a pair of separators 24 (24a, 24b) sandwiching the MEA 22. The MEA 22 has an electrolyte membrane 26, an anode electrode 28 provided on one surface of the electrolyte membrane 26, and a cathode electrode 30 provided on the other surface of the electrolyte membrane 26. The electrolyte membrane 26 is, for example, a solid polymer electrolyte membrane (cation exchange membrane). The separator 24a forms an anode gas flow path 32 for the anode gas to flow on one surface of the MEA 22. The separator 24b forms a cathode gas flow path 34 for the cathode gas to flow on the other surface of the MEA 22. In addition, a plurality of power generation cells 20 are stacked, thereby forming a refrigerant flow path 36 for the refrigerant to flow between the mutually facing surfaces of the separator 24a and the separator 24b.

[0029] Each power generation cell 20 has a plurality of communication holes (anode gas communication holes, cathode gas communication holes, and coolant communication holes) (not shown) that allow the anode gas, cathode gas, and coolant to flow along the stacking direction of the stack 21. The anode gas communication hole is connected to the anode gas flow path 32, the cathode gas communication hole is connected to the cathode gas flow path 34, and the coolant communication hole is connected to the coolant flow path 36.

[0030] The anode gas is supplied to the fuel cell stack 12 by the anode system device 14. In the fuel cell stack 12, the anode gas flows through the anode gas connecting hole (anode gas inlet connecting hole) and flows into the anode gas flow path 32. The anode gas is used for power generation at the anode electrode 28. The anode exhaust gas generated by power generation flows out from the anode gas flow path 32 to the anode gas connecting hole (anode gas outlet connecting hole) and is discharged from the fuel cell stack 12 to the anode system device 14. The anode exhaust gas includes unreacted hydrogen.

[0031] In addition, cathode gas is supplied to the fuel cell stack 12 by the cathode system device 16. In the fuel cell stack 12, the cathode gas flows through the cathode gas connecting hole (cathode gas inlet connecting hole) and flows into the cathode gas flow path 34. The cathode gas is used for power generation at the cathode electrode 30. The cathode exhaust gas generated for power generation flows out from the cathode gas flow path 34 to the cathode gas connecting hole (cathode gas outlet connecting hole), and is discharged from the fuel cell stack 12 to the cathode system device 16.

[0032] In addition, the cooling device 18 supplies the refrigerant to the fuel cell stack 12. In the fuel cell stack 12, the refrigerant flows through the refrigerant communication hole (refrigerant inlet communication hole) and flows into the refrigerant flow path 36. The refrigerant cools the power generation cell 20. The refrigerant that has cooled the power generation cell 20 flows out of the refrigerant flow path 36 to the refrigerant communication hole (refrigerant outlet communication hole), and is discharged from the fuel cell stack 12 to the cooling device 18.

[0033] The anode system device 14 of the fuel cell system 10 has an anode path 38. The anode path 38 includes: an anode supply path 40, which supplies anode gas to the fuel cell stack 12; and an anode exhaust path 42, which exhausts anode exhaust from the fuel cell stack 12. In addition, the anode path 38 has an anode circulation path 44 for returning unreacted hydrogen contained in the anode exhaust of the anode exhaust path 42 to the anode supply path 40. The anode circulation path 44 is connected to a discharge path 46, and the discharge path 46 allows a part of the anode exhaust to flow from the circulation loop of the anode system device 14 to the cathode system device 16.

[0034] A tank 47 for storing anode gas is provided at the upstream portion of the anode supply path 40. In addition, an ejector 48 and an ejector 50 are provided in sequence on the anode supply path 40 toward the downstream side in the flow direction of the anode gas. When the fuel cell system 10 is in operation, the ejector 48 is opened and closed to eject the anode gas having a lower pressure than that on the tank 47 side toward the downstream. The ejector 50 supplies the anode gas ejected from the ejector 48 to the fuel cell stack 12. In addition, the ejector 50 draws the anode exhaust gas from the anode circulation path 44 and supplies the drawn anode exhaust gas to the fuel cell stack 12. The ejector 50 draws the anode exhaust gas by using the negative pressure generated by the flow of the anode gas ejected from the ejector 48.

[0035] A gas-liquid separator 52 is provided in the anode discharge path 42. The gas-liquid separator 52 separates liquid water (generated water during power generation) contained in the anode exhaust from the anode exhaust. The anode circulation path 44 is connected to the upper portion of the gas-liquid separator 52. Thus, the anode exhaust (gas) that does not contain water in the gas-liquid separator 52 flows to the anode circulation path 44. The discharge path 54 discharges the separated water, and one end of the discharge path 54 is connected to the bottom of the gas-liquid separator 52. A discharge valve 56 for opening and closing the flow path is provided in the discharge path 54. In addition, a discharge valve 58 for opening and closing the flow path in the discharge path 46 is provided in the discharge path 46.

[0036] The cathode system device 16 of the fuel cell system 10 has a cathode path 60. The cathode path 60 includes a cathode supply path 62 that supplies cathode gas to the fuel cell stack 12, and a cathode exhaust path 64 that exhausts cathode exhaust gas from the fuel cell stack 12. In addition, a cathode bypass path 66 is connected between the cathode supply path 62 and the cathode exhaust path 64. Thus, the cathode gas in the cathode supply path 62 flows directly to the cathode exhaust path 64 without passing through the fuel cell stack 12.

[0037] An air pump 68 (air compressor) for supplying cathode gas to the fuel cell stack 12 is provided in the cathode supply path 62. When the fan blade (not shown) rotates, the air pump 68 compresses the air (external gas) on the upstream side of the air pump 68 and supplies it to the cathode supply path 62 on the downstream side. In addition, the air pump 68 involved in this embodiment is an axis floating type air pump that separates the fan blade from the peripheral wall surrounding the fan blade when the fan blade rotates.

[0038] The cathode supply path 62 is provided with a supply side sealing valve 70 on the downstream side of the air pump 68 and the cathode bypass path 66. The cathode supply path 62 is provided with a humidifier 72 between the supply side sealing valve 70 and the fuel cell stack 12. Moreover, although not shown in the figure, auxiliary equipment such as an intercooler for cooling the cathode gas may be provided in the cathode supply path 62. The discharge path 46 is connected to the cathode supply path 62 on the downstream side of the humidifier 72. Preferably, a gas-liquid separator (not shown) is provided at the connection portion between the cathode supply path 62 and the discharge path 46.

[0039] The humidifier 72 is provided across the cathode supply path 62 and the cathode discharge path 64. The humidifier 72 humidifies the cathode gas flowing in the cathode supply path 62 using moisture (such as generated water during power generation) contained in the cathode exhaust gas discharged from the fuel cell stack 12 to the cathode discharge path 64.

[0040] The cathode discharge path 64 is provided with a discharge side sealing valve 74 between the humidifier 72 and the cathode bypass path 66. In addition, the discharge path 54 of the anode system device 14 is connected to the cathode discharge path 64 on the downstream side of the cathode bypass path 66. The cathode bypass path 66 is provided with a bypass valve 76 for adjusting the flow rate of the cathode gas bypassing the fuel cell stack 12.

[0041] The sealing valve 69 includes a supply-side sealing valve 70 for opening and closing the cathode path 60 and a discharge-side sealing valve 74. More than one sealing valve 69 is provided. In the present embodiment, a butterfly valve whose opening can be adjusted linearly is applied to the sealing valve. Similarly, a butterfly valve whose opening can be adjusted linearly is applied to the bypass valve 76. Moreover, the supply-side sealing valve 70 and the discharge-side sealing valve 74 can also be valves that switch between opening (opening 100%) and closing (opening 0%) like solenoid valves. In addition, the fuel cell system 10 is not limited to having both the supply-side sealing valve 70 and the discharge-side sealing valve 74, and it is sufficient if it has at least one of these valves.

[0042] The cooling device 18 of the fuel cell system 10 has a refrigerant path 78 for circulating the refrigerant. The refrigerant path 78 has a refrigerant supply path 80 that supplies the refrigerant to the fuel cell stack 12, and a refrigerant discharge path 82 that discharges the refrigerant from the fuel cell stack 12. The refrigerant supply path 80 and the refrigerant discharge path 82 are connected to a radiator 84 that cools the refrigerant. A refrigerant pump 86 is provided in the refrigerant supply path 80. The refrigerant pump 86 circulates the refrigerant in the refrigerant circulation circuit (between the fuel cell stack 12, the refrigerant supply path 80, the refrigerant discharge path 82, and the radiator 84).

[0043] In addition, the fuel cell system 10 is provided with a plurality of temperature detection units 90 for detecting the temperature of the fuel cell system 10. The temperature detection unit 90 includes a refrigerant outlet temperature sensor 90a provided on the upstream side (fuel cell stack 12 side) of the refrigerant discharge path 82, a cathode temperature sensor 90b provided on the cathode supply path 62, and the like. The refrigerant outlet temperature sensor 90a is provided near the refrigerant discharge port of the fuel cell stack 12, thereby approximately detecting the temperature of the fuel cell stack 12. The cathode temperature sensor 90b is provided on the upstream side of the cathode bypass path 66 (and on the downstream side of the intercooler), thereby approximately detecting the peripheral temperature of the cathode system device 16. The peripheral temperature of the cathode system device 16 is also related to the temperature of the fuel cell stack 12. This means that detecting the peripheral temperature of the cathode system device 16 is also detecting temperature information related to the temperature of the fuel cell stack 12.

[0044] In addition, in order to obtain the inter-electrode pressure difference of the fuel cell stack 12, the fuel cell system 10 is provided with a plurality of pressure detection units 92. The pressure detection unit 92 includes: an anode pressure sensor 92a, which detects the pressure of the anode supply path 40 on the downstream side of the ejector 50; and a cathode pressure sensor 92b, which detects the pressure of the cathode supply path 62 on the downstream side of the air pump 68. The anode pressure sensor 92a detects the pressure in the circulation loop of the anode path 38, thereby approximately detecting the pressure on the anode electrode 28 side in the fuel cell stack 12. The cathode pressure sensor 92b detects the pressure in the cathode supply path 62, thereby approximately detecting the pressure on the cathode electrode 30 side in the fuel cell stack 12.

[0045] The above fuel cell system 10 has an ECU 100 (Electronic Control Unit), which controls the operation of each component of the fuel cell system 10. The ECU 100 is composed of a computer having one or more processors, a memory, an input / output interface, and a circuit. One or more processors of the ECU 100 execute processing on a program not shown in the figure stored in the memory, thereby controlling the operation of the air pump 68, the sealing valve 69, the bypass valve 76, etc. In addition, the ECU 100 involved in this embodiment performs a process of stopping the power generation of the fuel cell stack 12 during the operation of the mobile body 11 (hereinafter referred to as the power generation stop process). Moreover, the operation of the mobile body 11 includes situations such as the mobile body 11 is traveling and the movement is stopped.

[0046] In order to stop power generation, Figure 2 As shown, the ECU 100 includes a power generation request acquisition unit 102 , a temperature acquisition unit 104 , a pressure acquisition unit 106 , a valve state acquisition unit 108 , a stop operation determination unit 110 , and an operation control unit 112 .

[0047] During the operation of the mobile body 11, the power generation requirement acquisition unit 102 receives a signal of a power generation requirement sent from other ECUs. Examples of other ECUs include a travel control ECU that controls the travel motor Mt, a battery ECU that monitors the remaining battery level of the battery Bt, and the like. Moreover, the ECU 100 itself may also have the functions of a travel control ECU and a battery ECU, and may also calculate the power generation requirement based on the signal of a sensor (accelerator opening sensor, vehicle speed sensor, etc.). When the power generation requirement acquisition unit 102 receives a signal indicating that the power generation requirement is zero (power generation stop signal) during operation, it instructs the stop action determination unit 110 and the action control unit 112 to implement the power generation stop process.

[0048] During the operation of the mobile body 11, the temperature acquisition unit 104 acquires the temperature detected by the temperature detection unit 90 at an appropriate timing (for example, every predetermined period) and stores it in the memory. During the operation of the mobile body 11, the pressure acquisition unit 106 acquires the pressure detected by the pressure detection unit 92 at an appropriate timing (for example, every predetermined period) and stores it in the memory.

[0049] The valve state acquisition unit 108 acquires the state information (normal or abnormal) of the supply side sealing valve 70 and the discharge side sealing valve 74 from the abnormality detection unit 114. The abnormality detection unit 114 monitors whether each structural element of the fuel cell system 10 is in a normal state or an abnormal state by an appropriate detection and judgment method. In the event of an abnormality, the abnormality detection unit 114 stores its abnormality code in the memory (status register). For example, the abnormality detection unit 114 detects abnormalities such as the closing abnormality that cannot be switched from open to closed, the opening abnormality that cannot be switched from closed to open, etc. for the supply side sealing valve 70, the discharge side sealing valve 74, and the bypass valve 76, and stores the abnormality code corresponding to the abnormal content.

[0050] When the power generation requirement acquisition unit 102 receives an instruction to stop power generation (the power generation requirement is zero), the stop action determination unit 110 determines the processing content of the power generation stop process based on the temperature information of the temperature acquisition unit 104. Here, in the power generation stop process, the fuel cell system 10 involved in this embodiment performs a stop control to stop the power generation of the fuel cell stack 12 as a first control, and performs an idle control to slightly generate power for the fuel cell stack 12 as a second control. Therefore, the action control unit 112 is provided with: a stop control processing unit 116 for performing the stop control; and an idle control processing unit 118 for performing the idle control.

[0051] like Figure 3A as well as Figure 3B As shown, the stop control processing unit 116 stops the supply of cathode gas to the fuel cell stack 12 during the stop control. As a result, the power generation of the fuel cell stack 12 is set to zero. Specifically, the stop control processing unit 116 closes both or at least one of the supply side sealing valve 70 and the discharge side sealing valve 74 in the cathode system device 16, and on the other hand, opens the bypass valve 76. At this time, the ECU 100 causes the supply side sealing valve 70 to fully close the flow path of the cathode supply path 62 (opening 0%), and causes the discharge side sealing valve 74 to fully close the flow path of the cathode discharge path 64 (opening 0%). On the other hand, the ECU 100 causes the bypass valve 76 to fully open the flow path of the cathode bypass path 66 (opening 100%). As a result, the cathode gas supplied to the downstream side of the air pump 68 does not flow toward the fuel cell stack 12 but flows from the cathode supply path 62 to the cathode discharge path 64 through the cathode bypass path 66.

[0052] In addition, the ECU 100 closes both the supply-side sealing valve 70 and the discharge-side sealing valve 74. At the same time, the anode gas from the anode system device 14 continues to circulate, thereby consuming the residual oxygen (residual cathode gas) inside the fuel cell stack 12 and in the piping. That is, in the fuel cell stack 12, the anode gas reacts with the cathode gas, thereby consuming the residual oxygen in the cathode gas. By continuing to supply the anode gas, it is possible to avoid insufficient anode gas supplied to the fuel cell stack 12 when returning to normal power generation after the stop control is implemented.

[0053] In addition, the ECU 100 supplies power lower than the power during normal driving (normal power generation) from the battery Bt to the air pump 68 to operate the air pump 68. As a result, the blades of the air pump 68 rotate at a fixed speed, and air corresponding to the speed is supplied to the cathode supply path 62. In addition, during the stop control, the ECU 100 may adjust the power supplied from the battery Bt to the air pump 68 based on the waste power requirement value obtained from the battery ECU or the like.

[0054] Furthermore, in the fuel cell system 10 using the non-shaft floating air pump 68, the ECU 100 may also stop the rotation of the air pump 68 when executing the stop control (see Figure 3B Thus, it is possible to suppress the air pump 68 from consuming the power of the battery Bt.

[0055] According to the above stop control, the current or power output from the fuel cell stack 12 of the fuel cell system 10 to the driving motor Mt and the battery Bt is zero. In addition, the fuel cell system 10 supplies the power of the battery Bt to various electrical devices. By implementing such a stop control, for example, when the state of charge SOC of the battery Bt is high, even when regenerative power is generated, the regenerative power can be appropriately discarded. In addition, the membrane degradation of the electrolyte membrane 26 caused by the cathode gas of the cathode gas flow path 34 of the fuel cell stack 12 passing through the electrolyte membrane-electrode structure 22 can be reduced.

[0056] like Figure 4A as well as Figure 4B As shown, in idle control, the idle control processing unit 118 makes the supply amount of cathode gas supplied to the fuel cell stack 12 during power generation stop processing less than the supply amount of cathode gas supplied to the fuel cell stack 12 during normal driving. As a result, the power generation of the fuel cell stack 12 is reduced. Specifically, the idle control processing unit 118 opens both the supply side sealing valve 70 and the discharge side sealing valve 74, and also opens the bypass valve 76. As a result, the cathode gas flowing out to the downstream side of the air pump 68 is branched into a first airflow from the cathode supply path 62 toward the fuel cell stack 12 and a second airflow through the cathode bypass path 66 toward the cathode discharge path 64.

[0057] Therefore, the fuel cell system 10 generates power with suppressed power in the fuel cell stack 12 and supplies the generated power to various electrical devices including the air pump 68. In addition, the fuel cell system 10 supplies power from the battery Bt to various electrical devices including the air pump 68 as needed.

[0058] For example, in idle control, the ECU 100 supplies the air pump 68 with power that is greater than the power generated by the fuel cell stack 12. That is, when the power generated by the fuel cell stack 12 is A (W), the power consumed by the air pump 68 is A+B (W) (B is a positive number and a value lower than A). Thus, the power generated by the fuel cell stack 12 is consumed in the air pump 68 (waste power).

[0059] The air pump 68 rotates the fan blades at a rotation speed corresponding to the power, thereby supplying cathode gas from the air pump 68 to the cathode supply path 62. In addition, the ECU 100 adjusts the opening and closing (opening degree) of the bypass valve 76 according to the change of the generated power (or current) output by the fuel cell stack 12. For example, the ECU 100 performs the following control: if the current value output by the fuel cell stack 12 increases, the opening degree of the bypass valve 76 is reduced; if the current value output by the fuel cell stack 12 decreases, the opening degree of the bypass valve 76 is increased.

[0060] In addition, during the idle control, the ECU 100 fully opens both the supply side sealing valve 70 and the discharge side sealing valve 74 (opening 100%). As a result, the cathode gas flows smoothly to the fuel cell stack 12. In addition, the ECU 100 may adjust the opening of the sealing valve 69 (supply side sealing valve 70, discharge side sealing valve 74) according to the adjustment of the opening of the bypass valve 76. By adjusting the opening of the sealing valve 69, the power generated by the fuel cell stack 12 can be adjusted with further accuracy.

[0061] By implementing the above idle control, it is possible to suppress large potential fluctuations in the electric power generated by the fuel cell stack 12. Therefore, it is possible to suppress degradation of the pair of separators 24, the anode electrode 28, and the cathode electrode 30 due to potential fluctuations.

[0062] Back to Figure 2 When all of the following conditions (a) to (c) are satisfied, the stop action determination unit 110 determines that the above-mentioned stop control is to be implemented. Therefore, when any one of the conditions (a) to (c) is not satisfied, the stop action determination unit 110 determines that the idle control is to be implemented.

[0063] (a) The temperature of the fuel cell stack 12 and / or the ambient temperature of the cathode system device 16 exceeds a predetermined temperature value (determination temperature threshold value Tt).

[0064] (b) There is no closing abnormality in both the supply-side sealing valve 70 and the discharge-side sealing valve 74 .

[0065] (c) The inter-electrode pressure difference between the pressure on the anode electrode 28 side and the pressure on the cathode electrode 30 side is equal to or less than a predetermined pressure value (determination pressure difference threshold value Tp).

[0066] The condition (a) is used to determine the possibility of freezing of one or more sealing valves 69 or cathode path 60, etc., due to generated water produced when the fuel cell stack 12 generates electricity in the fuel cell system 10. Assuming that when any one of the one or more sealing valves 69 freezes in a closed state when the stop control is implemented, the start of power generation of the fuel cell stack 12 will be delayed or power generation will not be possible.

[0067] The stop action determination unit 110 stores in advance a determination temperature threshold Tt for estimating freezing. When the mobile body 11 is traveling, there is often a large difference between the temperature of the fuel cell stack 12 and the outside air temperature. Therefore, it is preferable to set the determination temperature threshold Tt in consideration of the time elapsed after the start of the start, measurement errors, etc.

[0068] The temperature information of the fuel cell stack 12 used for comparison with the judgment temperature threshold value Tt uses the detected temperature of the refrigerant outlet temperature sensor 90a provided in the refrigerant discharge path 82. In addition, the fuel cell system 10 may use the detected temperature of the cathode temperature sensor 90b provided in the cathode supply path 62 as the temperature information of the fuel cell stack 12. In the present embodiment, the stop action determination unit 110 uses both the detected temperature of the refrigerant outlet temperature sensor 90a and the detected temperature of the cathode temperature sensor 90b as temperature information for determination. Moreover, there is a correlation between the ambient temperature of the cathode system device 16 (the temperature of the cathode temperature sensor 90b) and the temperature of the fuel cell stack 12. Therefore, the stop action determination unit 110 may not use the ambient temperature of the cathode system device 16 as temperature information when making a determination.

[0069] Alternatively, the stop operation determination unit 110 may use an outside temperature sensor 90c (see Figure 1 ) as temperature information. For example, the stop action determination unit 110 may use the detected temperature of the refrigerant outlet temperature sensor 90a or the cathode temperature sensor 90b and the detected temperature of the external air temperature sensor 90c to estimate the possibility of freezing of the sealing valve 69 (supply side sealing valve 70, discharge side sealing valve 74).

[0070] Moreover, immediately after the start of the mobile body 11, there is a large difference between the temperature of the fuel cell stack 12 and the peripheral temperature of the cathode system device 16. Therefore, the value of the judgment temperature threshold Tt used to judge the temperature of the fuel cell stack 12 and the value used to monitor the peripheral temperature of the cathode system device 16 can be different values. For example, in the case of starting in an extremely low temperature environment, there is a possibility that a large difference will occur between the temperature of the fuel cell stack 12 and the peripheral temperature of the cathode system device 16. Therefore, when starting in an extremely low temperature environment, the judgment temperature threshold Tt used to judge the temperature of the fuel cell stack 12 and the peripheral temperature of the cathode system device 16 can be set to a value that can ensure that the freezing of each structural element is thawed.

[0071] When the temperature of the fuel cell stack 12 exceeds the judgment temperature threshold Tt, the stop action determination unit 110 determines that the condition (a) is satisfied. On the contrary, when the temperature of the fuel cell stack 12 is below the judgment temperature threshold Tt, the stop action determination unit 110 determines that the above condition (a) is not satisfied.

[0072] When any of the sealing valves 69 among more than one sealing valve is abnormally closed, the implementation of the stop control will be abnormal. The condition (b) is used to eliminate the abnormal closing of each valve. The stop action determination unit 110 monitors the status of each valve (supply side sealing valve 70, discharge side sealing valve 74) acquired by the valve status acquisition unit 108. Moreover, when all the valves are normal, the stop action determination unit 110 determines that the condition (b) is met, and when any of the sealing valves among the valves is abnormally closed, the stop action determination unit 110 determines that the condition (b) is not met.

[0073] When the inter-electrode pressure difference between the anode electrode 28 side and the cathode electrode 30 side in the fuel cell stack 12 is large, when the sealing valve 69 is closed, there is a possibility that the fuel cell stack 12 will be damaged. The condition (c) is used to exclude the state of large inter-electrode pressure difference. The stop action determination unit 110 calculates the absolute value of the inter-electrode pressure difference based on the pressure of the anode pressure sensor 92a and the pressure of the cathode pressure sensor 92b acquired by the pressure acquisition unit 106. Moreover, when the calculated inter-electrode pressure difference is below the judgment pressure difference threshold Tp, the stop action determination unit 110 determines that the condition (c) is met, and when the calculated inter-electrode pressure difference exceeds the judgment pressure difference threshold Tp, the stop action determination unit 110 determines that the condition (c) is not met.

[0074] In addition, the stop action determination unit 110 also continuously monitors the above-mentioned conditions (a) to (c) when implementing the stop control. For example, even when the stop control is implemented, the stop action determination unit 110 transfers from the stop control to the idle control when the temperature of the fuel cell stack 12 is below the determination temperature threshold Tt. Alternatively, even when the idle control is implemented based on the condition (a) not being satisfied, the stop action determination unit 110 transfers from the idle control to the stop control when the temperature of the fuel cell stack 12 exceeds the determination temperature threshold Tt. For another example, even when the idle control is implemented based on the conditions (a) and (b) being satisfied and the condition (c) being not satisfied, the stop action determination unit 110 transfers from the idle control to the stop control when the subsequent inter-electrode pressure difference is below the determination pressure difference threshold Tp.

[0075] Furthermore, the stop action determination unit 110 may not determine all of the conditions (a) to (c), but may at least determine whether the temperature of the fuel cell stack 12 exceeds the determination temperature threshold Tt (condition (a) is satisfied or not). In the case where there is no possibility of freezing of the fuel cell system 10, the stop control is implemented to preferentially suppress the degradation of the electrolyte membrane 26, thereby significantly improving the durability of the fuel cell stack 12.

[0076] The fuel cell system 10 according to the present embodiment is basically configured as described above. The operation thereof will be described below.

[0077] The mobile body 11 is in operation (operating due to the ignition device or the start switch being turned on), and is traveling based on the user's driving operation or the automatic driving of the control device of the mobile body 11. Even if the surrounding environment is low temperature at the time of starting, it is preheated at the time of starting, so that the fuel cell stack 12, the anode system device 14, and the cathode system device 16 are in a state where they will not freeze. Therefore, if the fuel cell stack 12 does not stop power generation during the travel of the mobile body 11, one or more sealing valves 69 and bypass valves 76 can be opened and closed to allow the cathode gas to flow.

[0078] During normal travel of the mobile body 11, the fuel cell system 10 operates the anode system device 14 and the cathode system device 16. The anode system device 14 supplies anode gas to the fuel cell stack 12. The cathode system device 16 supplies cathode gas to the fuel cell stack 12. As a result, the fuel cell stack 12 generates electricity, and the generated electricity is supplied to the travel motor Mt and the battery Bt, etc.

[0079] In addition, during operation (driving or stopped), when the ECU 100 receives a request for power generation from a driving control ECU or a battery ECU (not shown), it generates power according to the following steps: Figure 5The process flow shown starts with the power generation stop process.

[0080] Specifically, during operation, the ECU 100 receives a power generation stop signal via the power generation requirement acquisition unit 102 (step S1). When receiving the power generation stop instruction from the power generation requirement acquisition unit 102, the stop operation determination unit 110 determines whether the temperature of the fuel cell stack 12 (refrigerant outlet temperature sensor 90a) acquired by the temperature acquisition unit 104 at that time point exceeds the determination temperature threshold value Tt (step S2).

[0081] When the temperature of the fuel cell stack 12 is below the judgment temperature threshold Tt (step S2: No), the process proceeds to step S3, and the stop action judgment unit 110 judges that idle control is to be implemented. During idle control, the action control unit 112 opens the supply side sealing valve 70, the discharge side sealing valve 74 and the bypass valve 76 of the cathode system device 16. In addition, the action control unit 112 supplies a larger amount of power than the power generated by the fuel cell stack 12 to the air pump 68 from the fuel cell stack 12 and the battery Bt, thereby consuming the power generated by the fuel cell stack 12. A portion of the cathode gas supplied from the air pump 68 to the cathode supply path 62 is discharged to the cathode discharge path 64 via the cathode bypass path 66. As a result, the flow rate of the cathode gas toward the fuel cell stack 12 is adjusted to an amount corresponding to the power generated by the fuel cell stack 12.

[0082] On the other hand, when the temperature of the fuel cell stack 12 exceeds the judgment temperature threshold Tt (step S2: Yes), the stop action determination unit 110 proceeds to step S4. In step S4, the stop action determination unit 110 determines whether the ambient temperature of the cathode system device 16 (the temperature of the cathode temperature sensor 90b) acquired by the temperature acquisition unit 104 at the instruction time point of power generation stop exceeds the judgment temperature threshold Tt. When the ambient temperature of the cathode system device 16 is below the judgment temperature threshold Tt (step S4: No), the stop action determination unit 110 proceeds to step S3. On the other hand, when the ambient temperature of the cathode system device 16 exceeds the judgment temperature threshold Tt (step S4: Yes), the stop action determination unit 110 proceeds to step S5.

[0083] In step S5, the stop operation determination unit 110 determines whether the states of the supply side sealing valve 70 and the discharge side sealing valve 74 acquired by the valve state acquisition unit 108 are normal or abnormal. When either the supply side sealing valve 70 or the discharge side sealing valve 74 is abnormally closed (step S5: No), the stop operation determination unit 110 proceeds to step S3. On the other hand, when both the supply side sealing valve 70 and the discharge side sealing valve 74 are normal (step S5: Yes), the stop operation determination unit 110 proceeds to step S6.

[0084] In step S6, the stop operation determination unit 110 calculates the inter-electrode pressure difference based on the pressure of the anode pressure sensor 92a and the pressure of the cathode pressure sensor 92b acquired via the pressure acquisition unit 106. The stop operation determination unit 110 determines whether the inter-electrode pressure difference is less than the judgment pressure difference threshold value Tp. When the inter-electrode pressure difference exceeds the judgment pressure difference threshold value Tp (step S6: No), the stop operation determination unit 110 proceeds to step S7.

[0085] In step S7, the stop action determination unit 110 waits until the power generated by the fuel cell stack 12 is less than the predetermined power. When the standby of step S7 ends, the stop action determination unit 110 transfers to step S8. Moreover, the processing of step S7 is not limited to the above, and it may be that the standby is carried out until the inter-electrode pressure difference is less than the judgment pressure difference threshold Tp. Alternatively, it may be that the stop action determination unit 110 does not implement step S7, but implements step S3 when the pressure difference exceeds the judgment pressure difference threshold Tp.

[0086] On the other hand, in step S6, when the inter-electrode pressure difference is below the judgment pressure difference threshold value Tp (step S6: yes) or after implementing step S7, the stop action determination unit 110 determines that the stop control is to be implemented (step S8). In the stop control, the action control unit 112 fully closes the supply side sealing valve 70 and the discharge side sealing valve 74 of the cathode system device 16, and fully opens the bypass valve 76. In addition, the action control unit 112 drives the air pump 68 to supply cathode gas from the air pump 68 to the cathode supply path 62. The supply side sealing valve 70 and the discharge side sealing valve 74 are fully closed, so that the cathode gas is discharged to the cathode discharge path 64 via the cathode bypass path 66. As a result, the cathode gas does not flow into the fuel cell stack 12, so the fuel cell stack 12 stops generating electricity after the remaining cathode gas is consumed.

[0087] In addition, when executing the stop control, the ECU 100 performs Figure 6 The processing flow shown. That is, the stop action determination unit 110 determines whether the temperature of the fuel cell stack 12 (refrigerant outlet temperature sensor 90a) after the stop control exceeds the determination temperature threshold Tt (step S11). Moreover, when the temperature of the fuel cell stack 12 is below the determination temperature threshold Tt (step S11: No), the stop action determination unit 110 proceeds to step S12 and switches from the stop control to the idle control. On the other hand, when the temperature of the fuel cell stack 12 exceeds the determination temperature threshold Tt (step S11: Yes), the stop action determination unit 110 proceeds to step S13.

[0088] In step S13, the stop operation determination unit 110 determines whether the ambient temperature of the cathode system device 16 (the temperature of the cathode temperature sensor 90b) after the control is stopped exceeds the determination temperature threshold Tt. When the ambient temperature of the cathode system device 16 is lower than the determination temperature threshold Tt (step S13: No), the stop operation determination unit 110 proceeds to step S12. On the other hand, when the ambient temperature of the cathode system device 16 exceeds the determination temperature threshold Tt (step S13: Yes), the stop operation determination unit 110 proceeds to step S14.

[0089] In step S14, the stop operation determination unit 110 determines whether the states of the supply side sealing valve 70 and the discharge side sealing valve 74 after the stop control are normal or abnormal. When any one of the supply side sealing valve 70 and the discharge side sealing valve 74 is abnormally closed (step S14: No), the stop operation determination unit 110 proceeds to step S12. On the other hand, when both the supply side sealing valve 70 and the discharge side sealing valve 74 are normal (step S14: Yes), the stop operation determination unit 110 proceeds to step S15.

[0090] In step S15, the stop action determination unit 110 determines that the stop control is continued. In this way, during the stop control, the ECU 100 implements the stop control by the action control unit 112, and repeats the processing flow of steps S11 to S15, thereby being able to transfer from the stop control to the idle control. When the fuel cell system 10 continues to perform the stop control, there may be a concern that one or more sealing valves 69 may freeze due to the influence of the external temperature, etc. However, the fuel cell system 10 transfers from the stop control to the idle control, thereby being able to avoid freezing.

[0091] When implementing the idle speed control, the ECU 100 performs Figure 7 The processing flow shown. That is, the stop action determination unit 110 determines whether the temperature of the fuel cell stack 12 (refrigerant outlet temperature sensor 90a) after the idle control is below the determination temperature threshold Tt (step S21). Moreover, when the temperature of the fuel cell stack 12 is maintained below the determination temperature threshold Tt (step S21: yes), the stop action determination unit 110 proceeds to step S22 and continues the idle control. On the other hand, when the temperature of the fuel cell stack 12 exceeds the determination temperature threshold Tt (step S21: no), the stop action determination unit 110 proceeds to step S23.

[0092] In step S23, the stop operation determination unit 110 determines whether the ambient temperature of the cathode system device 16 (the temperature of the cathode temperature sensor 90b) after the idle control exceeds the determination temperature threshold Tt. When the ambient temperature of the cathode system device 16 is less than the determination temperature threshold Tt (step S23: No), the stop operation determination unit 110 proceeds to step S22. On the other hand, when the ambient temperature of the cathode system device 16 exceeds the determination temperature threshold Tt (step S23: Yes), the stop operation determination unit 110 proceeds to step S24.

[0093] In step S24, the stop operation determination unit 110 switches from the idle control to the stop control. In this way, the ECU 100 performs the idle control by the operation control unit 112 and repeats the processing flow of steps S21 to S24, thereby being able to shift from the idle control to the stop control.

[0094] Furthermore, when the ECU 100 performs idle control based on the abnormal closing of the sealing valve 69 obtained from the abnormality detection unit 114, the stop control is prohibited and the idle control is continued. In other words, the processing flow of the above-mentioned steps S21 to S24 is not performed. Thus, it is possible to prevent the ECU 100 from switching to the stop control without any preparation during the idle control performed when the sealing valve 69 is abnormally closed.

[0095] The present invention is not limited to the above-mentioned embodiment, and various changes can be made according to the main purpose of the invention. For example, the cathode discharge path 64 may be provided with a back pressure valve (not shown) in addition to the discharge side sealing valve 74. In this case, when performing stop control or idle control, the back pressure valve can perform the same opening and closing action as the discharge side sealing valve 74.

[0096] In addition, the determination temperature threshold Tt when the stop control is executed and the idle control is executed may be set to a value different from the determination temperature threshold Tt used when the power generation stop process is started. Fig. 8A , Figure 8B , illustrating the processing flow in the stop control and idle control of the fuel cell system 10 involved in the modification.

[0097] like Fig. 8AAs shown, in the stop control, the stop action determination unit 110 determines whether the temperature of the fuel cell stack 12 (refrigerant outlet temperature sensor 90a) after the stop control exceeds the value obtained by adding the first margin tx to the judgment temperature threshold Tt (step S31). The change in the temperature of the fuel cell stack 12 relative to the temperature of the surrounding environment when the stop control is implemented is obtained by conducting experiments in advance, and the first margin tx is determined. Moreover, when the temperature of the fuel cell stack 12 is below Tt+tx (step S31: No), the stop action determination unit 110 proceeds to step S32 and switches from stop control to idle control. On the other hand, when the temperature of the fuel cell stack 12 exceeds Tt+tx (step S31: Yes), proceed to step S33.

[0098] In step S33, the stop operation determination unit 110 determines whether the ambient temperature of the cathode system device 16 (the temperature of the cathode temperature sensor 90b) after the stop control exceeds the value obtained by adding the second margin ty to the determination temperature threshold Tt. The second margin ty is determined by performing experiments in advance to find the change in the ambient temperature of the cathode system device 16 relative to the temperature of the surrounding environment when the stop control is implemented. When the ambient temperature of the cathode system device 16 is less than Tt+ty (step S33: No), the stop operation determination unit 110 proceeds to step S32. When the ambient temperature of the cathode system device 16 exceeds Tt+ty (step S33: Yes), the stop operation determination unit 110 proceeds to step S34.

[0099] In step S34, the stop operation determination unit 110 determines whether the states of the supply side sealing valve 70 and the discharge side sealing valve 74 after the stop control are normal or abnormal. When either the supply side sealing valve 70 or the discharge side sealing valve 74 is abnormally closed (step S34: No), the stop operation determination unit 110 proceeds to step S32. When both the supply side sealing valve 70 and the discharge side sealing valve 74 are normal (step S34: Yes), the stop operation determination unit 110 proceeds to step S35. In step S35, the stop operation determination unit 110 determines that the stop control is continued.

[0100] In addition, if Figure 8B As shown, during the idle control, the stop action determination unit 110 of the ECU 100 determines whether the temperature of the fuel cell stack 12 (refrigerant outlet temperature sensor 90a) after the idle control is less than or equal to a fixed value of the determination temperature threshold Ttf (step S41). Preferably, the determination temperature threshold Ttf is set to an appropriate value in consideration of the temperature dependence of the chemical degradation of the fuel cell stack 12.

[0101] When the temperature of the fuel cell stack 12 is maintained below the determination temperature threshold Ttf (step S41: Yes), the stop action determination unit 110 proceeds to step S42 and continues the idle control. On the other hand, when the temperature of the fuel cell stack 12 exceeds the determination temperature threshold Ttf (step S41: No), the stop action determination unit 110 proceeds to step S43, and the action control unit 112 transfers to the stop control. In this way, by using the determination temperature threshold Ttf higher than the determination temperature threshold Tt, the fuel cell system 10 can stably transfer from the idle control to the stop control.

[0102] The technical ideas and effects that can be grasped according to the above-mentioned embodiments are described below.

[0103] One embodiment of the present invention relates to a fuel cell system 10, which is arranged on a mobile body 11, and the fuel cell system 10 includes: a fuel cell stack 12; a cathode supply path 62, which supplies cathode gas to the fuel cell stack 12; a cathode exhaust path 64, which exhausts cathode exhaust from the fuel cell stack 12; a bypass path (cathode bypass path 66), which connects the cathode supply path 62 to the cathode exhaust path 64 in a manner that bypasses the fuel cell stack 12; an air pump 68, which supplies cathode gas to the cathode supply path 62; one or more sealing valves 69, one or more sealing valves 69 are arranged between a connection portion in the cathode supply path 62 connected to the bypass path and the fuel cell stack 12, or between a connection portion in the cathode exhaust path 64 connected to the bypass path and the fuel cell stack 12; a bypass valve 76, which is arranged in the bypass path; and a control device (ECU 100), which controls the operation of the air pump 68, one or more sealing valves 69 and the bypass valve 76. The control device obtains temperature information related to the temperature of the fuel cell stack 12 from the temperature detection unit 90 provided in the fuel cell system 10. When the mobile body 11 receives a signal related to the cessation of power generation of the fuel cell stack 12 during the operation of the mobile body 11, the control device determines whether the obtained temperature information exceeds a predetermined temperature value (the temperature threshold Tt for determination). When it is determined that the temperature information exceeds the predetermined temperature value, the control device closes the one or more sealing valves 69 and opens the bypass valve 76, thereby performing a first control (stop control) to stop the power generation of the fuel cell stack 12. When it is determined that the temperature information is below the predetermined temperature value, the control device operates the air pump 68, thereby performing a second control (idle control) to enable the fuel cell stack 12 to generate power with a power smaller than the power consumption of the air pump 68.

[0104] According to the above, when the temperature information exceeds a predetermined temperature value (determination temperature threshold Tt) during the operation of the mobile body 11, as a first control (stop control), the fuel cell system 10 stops supplying cathode gas to the fuel cell stack 12. As a result, the fuel cell system 10 can suppress power consumption and stop power generation of the fuel cell stack 12, and can suppress degradation of the electrolyte membrane 26 due to the cathode gas. On the other hand, when the temperature of the fuel cell stack 12 is below a predetermined temperature value, there is a possibility that one or more sealing valves 69 are frozen and cannot be closed. Therefore, the fuel cell system 10 performs a second control to consume the power generated by the fuel cell stack 12 with the air pump 68, thereby making it possible to output substantially no power as a whole system.

[0105] In addition, when it is determined that the temperature information is below a predetermined temperature value (determination temperature threshold value Tt) during the running of the mobile body 11, the control device (ECU 100) implements the second control. As a result, the fuel cell system 10 can perform power generation stop processing taking into account the possibility that one or more sealing valves 69 are frozen and cannot move during the running of the mobile body 11, and can make the fuel cell system 10 as a whole substantially without outputting power.

[0106] Furthermore, the control device (ECU 100) opens all of the one or more sealing valves 69 in the second control. Thus, the fuel cell system 10 can flow the cathode gas in the fuel cell stack 12 reliably and stably in the second control.

[0107] Furthermore, the control device (ECU 100) stops the rotation of the air pump 68 in the first control. Thus, the fuel cell system 10 can suppress a decrease in the remaining battery level of the battery Bt when the first control is performed.

[0108] In addition, when the temperature information is below a predetermined temperature value (determination temperature threshold Tt) during the implementation of the first control, the control device (ECU 100) stops the first control and switches to the second control. Here, when the fuel cell system 10 continuously stops the power generation of the fuel cell stack 12 through the first control, there is a possibility that one or more sealing valves 69 may freeze due to the influence of the ambient temperature. Therefore, the ECU 100 continues to monitor the temperature information even in the first control, and switches from the first control to the second control when the temperature information is below a predetermined temperature value. Thus, the heat generated by the power generation of the fuel cell stack 12 can be used to heat the one or more sealing valves 69. Therefore, freezing of one or more sealing valves 69 can be avoided.

[0109] In addition, when the temperature information exceeds a predetermined temperature value (determination temperature threshold value Tt) during the implementation of the second control, the control device (ECU 100) stops the second control and switches to the first control. When the fuel cell system 10 causes the fuel cell stack 12 to continue to generate electricity through the second control, the temperature of the sealing valve 69 increases due to the heat of power generation and is difficult to freeze. Therefore, the ECU 100 switches from the second control to the first control when the temperature information exceeds a predetermined temperature value, thereby suppressing the degradation of the electrolyte membrane 26.

[0110] In addition, an abnormality detection unit 114 is provided, which detects whether one or more sealing valves 69 are normal or abnormal. When a closing abnormality that any one of the one or more sealing valves 69 cannot be closed is obtained from the abnormality detection unit 114, the control device (ECU 100) prohibits the first control and implements the second control. When one or more sealing valves 69 are closed abnormally, the fuel cell system 10 cannot execute the first control, and thus performs the second control, thereby making it possible to make the fuel cell system 10 as a whole substantially have no power output.

[0111] In addition, the control device (ECU 100) obtains pressure information related to the pressure on the anode electrode 28 side and the pressure on the cathode electrode 30 side of the fuel cell stack 12 from the pressure detection unit 92 provided in the fuel cell system 10, and the control device (ECU 100) determines whether the inter-electrode pressure difference between the pressure on the anode electrode 28 side and the pressure on the cathode electrode 30 side exceeds a predetermined pressure value (determination pressure difference threshold value Tp). When the inter-electrode pressure difference exceeds the predetermined pressure value, the control device (ECU 100) at least temporarily prohibits the first control. When more than one sealing valve 69 is closed when the inter-electrode pressure difference is large, there is a possibility that the pair of separators 24 and the fuel cell stack 12 are damaged. Therefore, the fuel cell system 10 temporarily prohibits the first control, thereby preventing the pair of separators 24 and the fuel cell stack 12 from being damaged.

[0112] In addition, when it is determined that the temperature information exceeds a predetermined temperature value and the first control is prohibited based on the fact that the inter-electrode pressure difference exceeds a predetermined pressure value (determination pressure difference threshold value Tp), the control device (ECU 100) waits until the power of the fuel cell stack 12 drops to a predetermined value, or waits until the inter-electrode pressure difference is below a predetermined pressure value, and then implements the first control after waiting. Thus, the fuel cell system 10 can implement the first control after the inter-electrode pressure difference decreases, can prevent the pair of separators 24 and the fuel cell stack 12 from being damaged, and can suppress the degradation of the electrolyte membrane 26.

[0113] In addition, the control device (ECU 100) fully opens the bypass valve in the first control, and adjusts the opening of the bypass valve in the second control according to the power generation of the fuel cell stack 12. As a result, the fuel cell system 10 can smoothly discharge the cathode gas from the cathode supply path 62 in the first control. In addition, an appropriate amount of cathode gas can be supplied to the fuel cell stack 12 in the second control.

[0114] Furthermore, when the control device (ECU 100) implements the first control, the anode gas continues to flow through the fuel cell stack 12. Thus, when the fuel cell system 10 returns to normal power generation after implementing the first control, it is possible to avoid anode gas shortage to the fuel cell stack 12 (ensure a sufficient air-fuel ratio).

Claims

1. A fuel cell system, which is arranged on a mobile body (11), wherein the fuel cell system (10) comprises: Fuel cell stack (12); a cathode supply path (62) for supplying cathode gas to the fuel cell stack; a cathode exhaust path (64) for exhausting cathode exhaust gas from the fuel cell stack; a bypass passage (66) connecting the cathode supply passage and the cathode exhaust passage in a manner bypassing the fuel cell stack; an air pump (68) for supplying the cathode gas to the cathode supply path; A supply-side sealing valve (70) provided between a connection portion of the cathode supply path connected to the bypass path and the fuel cell stack; a discharge side sealing valve (74) provided between a connection portion of the cathode discharge passage connected to the bypass passage and the fuel cell stack; a bypass valve (76) disposed in the bypass passage; as well as A control device (100) controls the operation of the air pump, the supply-side sealing valve, the discharge-side sealing valve, and the bypass valve, The control device acquires temperature information related to the temperature of the fuel cell stack from a temperature detection unit (90) provided in the fuel cell system. When the control device receives a signal related to stopping power generation of the fuel cell stack during operation of the mobile body, it determines whether the acquired temperature information exceeds a predetermined temperature value (Tt), When it is determined that the temperature information exceeds the predetermined temperature value, the control device closes the supply-side sealing valve and the discharge-side sealing valve and opens the bypass valve while supplying power from the battery to the air pump to operate the air pump, so that the cathode gas supplied to the downstream side of the air pump does not flow toward the fuel cell stack but flows from the cathode supply path through the bypass path to the cathode discharge path, thereby performing a first control to stop power generation of the fuel cell stack. The control device operates the air pump when it is determined that the temperature information is equal to or lower than the predetermined temperature value during travel of the mobile body, thereby performing second control to cause the fuel cell stack to generate power with less power than power consumption of the air pump.

2. The fuel cell system according to claim 1, characterized in that: The control device stops the first control and switches to the second control when the temperature information is equal to or lower than the predetermined temperature value during the execution of the first control.

3. The fuel cell system according to claim 1, characterized in that: The control device stops the second control and switches to the first control when the temperature information exceeds the predetermined temperature value during the implementation of the second control.

4. The fuel cell system according to claim 1, characterized in that: An abnormality detection unit (114) is provided, wherein the abnormality detection unit (114) detects whether the supply side sealing valve or the discharge side sealing valve is normal or abnormal. The control device prohibits the first control and implements the second control when a closing abnormality in which the supply-side sealing valve or the discharge-side sealing valve cannot be closed is acquired from the abnormality detection unit.

5. The fuel cell system according to claim 1, characterized in that: The control device acquires pressure information related to the pressure on the anode electrode (28) side and the pressure on the cathode electrode (30) side of the fuel cell stack from a pressure detection unit (92) provided in the fuel cell system. The control device determines whether the inter-electrode pressure difference between the pressure on the anode electrode side and the pressure on the cathode electrode side exceeds a predetermined pressure value (Tp). The control device at least temporarily prohibits the first control when the inter-electrode pressure difference exceeds the predetermined pressure value.

6. The fuel cell system according to claim 5, characterized in that: When the control device determines that the temperature information exceeds the predetermined temperature value and prohibits the first control based on the fact that the inter-electrode pressure difference exceeds the predetermined pressure value, the control device waits until the power of the fuel cell stack drops to a predetermined value, or waits until the inter-electrode pressure difference is below the predetermined pressure value, and implements the first control after waiting.

7. The fuel cell system according to claim 1, characterized in that: In the first control, the control device makes the bypass valve fully open. The control device adjusts the opening degree of the bypass valve according to the amount of power generation of the fuel cell stack in the second control.

8. The fuel cell system according to claim 1, characterized in that: When executing the first control, the control device continues to flow the anode gas through the fuel cell stack.

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