fuel cell system

Abstract

To suppress the deterioration of an injector.SOLUTION: A fuel battery system comprises a fuel battery stack, an injector assembly, a control device, a supply path, and a circulation path. The fuel battery stack performs power generation by reaction of anode gas and cathode gas. The injector assembly injects the anode gas. The injector assembly comprises a plurality of injectors. The supply path connects the injector assembly and an inflow port of an anode channel. The circulation path connects an outflow port of the anode channel and a supply path. The control device determines the necessity / unnecessity of water draining from the anode channel. The control device, when water draining is necessary, decides an operation state in which the pressure of the anode channel becomes a target pressure and the plurality of injectors inject the node gas. The control device makes the plurality of injectors inject the anode gas according to the operation state.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to fuel cell systems. [Background technology]

[0002] The fuel cell system disclosed in Patent Document 1 includes a fuel cell stack and an injector. The fuel cell stack includes an anode flow path and a cathode flow path. The fuel cell stack generates electricity through a reaction between an anode gas supplied to the anode flow path and a cathode gas supplied to the cathode flow path. The injector injects the anode gas. The anode gas injected from the injector is supplied to the anode flow path.

[0003] When water stagnates in the anode flow path, the pressure loss in the anode flow path increases and the reaction rate of the anode gas in the fuel cell stack decreases, resulting in a decrease in the power generation efficiency of the fuel cell stack. In Patent Document 1, when water stagnates in the anode flow path, the injector is controlled to increase the amount of anode gas injected from the injector. This increases pressure upstream of the anode flow path, thereby discharging water from the anode flow path. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-61239 Summary of the Invention [Problem to be solved by the invention]

[0005] Repeatedly injecting anode gas into the injector in order to expel water from the anode flow path may accelerate deterioration of the injector. [Means for solving the problem]

[0006] A fuel cell system that solves the above problem includes a fuel cell stack that generates electricity by reaction between an anode gas and a cathode gas, an injector assembly that injects the anode gas, and a control device, wherein the fuel cell stack includes an anode flow path to which the anode gas is supplied, and the injector assembly includes a plurality of injectors, and the fuel cell system includes a supply path that connects the injector assembly to an inlet of the anode flow path, and a circulation path that connects an outlet of the anode flow path to the supply path, and the control device determines whether or not water needs to be drained from the anode flow path, and if water drainage is required, determines an operating state of the injector assembly that will cause the pressure in the anode flow path to reach a target pressure and that will cause the plurality of injectors to inject the anode gas, and causes the plurality of injectors to inject the anode gas in accordance with the operating state.

[0007] This reduces the number of times that each injector injects anode gas compared to when a single injector is used to set the pressure in the anode flow path to the target pressure, thereby suppressing deterioration of the injector.

[0008] In the above fuel cell system, when some of the plurality of injectors are designated as first injectors, the control device, when injecting the anode gas from the plurality of injectors in accordance with the operating state, may start injection of the anode gas from a second injector of the plurality of injectors, which is different from the first injector, after a predetermined time has elapsed since starting injection of the anode gas from the first injector.

[0009] The fuel cell system may further include a circulation pump that supplies the anode gas from the circulation path to the supply path, and when injecting the anode gas into the plurality of injectors in accordance with the operating state, the control device may inject the anode gas into the injectors while operating the circulation pump. [Effects of the Invention]

[0010] According to the present invention, deterioration of the injector can be suppressed. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic configuration diagram of a vehicle. [Figure 2] FIG. 2 is a schematic diagram of an injector assembly. [Figure 3] 4 is a flowchart showing control performed by a control device. [Figure 4] FIG. 10 is a diagram illustrating an inrush current. [Figure 5] 4 is a timing chart showing the opening and closing of a first injector and a second injector. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of a fuel cell system will be described below. 1, a vehicle 10 includes a battery 11, a drive circuit 12, and a fuel cell system 20. The vehicle 10 includes a passenger car and an industrial vehicle. The industrial vehicle is, for example, a forklift or a towing tractor.

[0013] The fuel cell system 20 includes a fuel cell stack 21, a voltage sensor 27, a cathode system 30, an anode system 40, a diluter 61, a water storage tank 62, and a control device . The fuel cell stack 21 is, for example, a polymer electrolyte fuel cell. The fuel cell stack 21 includes a plurality of fuel cell units 22. Each fuel cell unit 22 includes an anode electrode to which an anode gas is supplied, a cathode electrode to which a cathode gas is supplied, and an electrolyte membrane disposed between the anode electrode and the cathode electrode. The fuel cell units 22 are sandwiched between separators.

[0014] The fuel cell stack 21 includes a cathode flow path 23 and an anode flow path 24. A cathode gas flows through the cathode flow path 23. An anode gas flows through the anode flow path 24. The anode flow path 24 is provided, for example, in a separator facing the anode electrode. The cathode flow path 23 is provided, for example, in a separator facing the cathode electrode. The anode flow path 24 includes an inlet 25 and an outlet 26. The anode gas flows into the anode flow path 24 from the inlet 25 and flows out from the outlet 26. The fuel cell stack 21 generates power by a reaction between the anode gas and the cathode gas. The cathode gas is an oxidant gas. An example of the oxidant gas is oxygen in the air. The anode gas is a fuel gas. An example of the fuel gas is hydrogen gas.

[0015] The voltage sensor 27 detects the voltage of each of the multiple fuel cell units 22 that make up the fuel cell stack 21. That is, the multiple fuel cell units 22 are electrically connected in series. The voltage of the fuel cell stack 21 is the sum of the voltages generated by the power generation of each of the fuel cell units 22.

[0016] The cathode system 30 includes a cathode gas inlet 31 , an electric compressor 32 , a flow meter 33 , an exhaust passage 34 , and a pressure adjusting valve 35 . The cathode gas inlet 31 is an inlet for drawing cathode gas into the fuel cell system 20. When oxygen in the air is used as the cathode gas, the cathode gas inlet 31 may be open to the atmosphere. The cathode gas inlet 31 may be connected to a gas cylinder that stores the cathode gas.

[0017] The electric compressor 32 is driven by an electric motor. The electric compressor 32 supplies cathode gas to the fuel cell stack 21. Specifically, the electric compressor 32 compresses the cathode gas supplied from the cathode gas inlet 31 and supplies the compressed cathode gas to the fuel cell stack 21. The cathode gas supplied from the electric compressor 32 to the fuel cell stack 21 flows through the cathode flow path 23.

[0018] The flow meter 33 measures the flow rate of the cathode gas supplied to the fuel cell stack 21. The flow meter 33 is provided between the cathode gas inlet 31 and the electric compressor 32. This makes it less susceptible to pressure fluctuations in the cathode gas caused by the electric compressor 32. The flow meter 33 may be provided between the electric compressor 32 and the fuel cell stack 21.

[0019] The exhaust path 34 is a passage through which the cathode exhaust gas flows. The cathode exhaust gas is cathode gas discharged from the fuel cell stack 21 and contains produced water. The produced water is water produced by the power generation in the fuel cell stack 21.

[0020] The pressure regulating valve 35 is provided in the exhaust path 34. The pressure regulating valve 35 regulates the pressure of the cathode exhaust gas. The pressure regulating valve 35 regulates the pressure of the cathode exhaust gas, for example, by changing the cross-sectional area of ​​the flow path.

[0021] The diluter 61 is connected to the exhaust path 34. The cathode exhaust gas is supplied to the diluter 61. The diluter 61 separates the cathode exhaust gas into cathode gas and generated water. The diluter 61 also functions as a gas-liquid separator.

[0022] The anode system 40 includes a tank 41, a first connection path 42, a regulator 43, an injector assembly 50, a second connection path 44, a supply path 45, a circulation path 46, a gas-liquid separator 47, an exhaust / drain valve 48, a circulation pump 49, and a pressure sensor 60.

[0023] The tank 41 stores the anode gas. The first connection path 42 connects the tank 41 and the regulator 43. The anode gas is supplied from the tank 41 to the regulator 43.

[0024] The regulator 43 reduces the pressure of the anode gas supplied from the tank 41. The regulator 43 reduces the pressure of the anode gas to a constant pressure. The constant pressure allows for tolerance.

[0025] 2, the injector assembly 50 includes multiple injectors 51, 52, and 53. For example, three injectors 51, 52, and 53 are provided. The injectors 51, 52, and 53 are members for adjusting the amount of anode gas supplied to the fuel cell stack 21. The amount of anode gas supplied to the fuel cell stack 21 can be adjusted by controlling the injectors 51, 52, and 53.

[0026] Each of the injectors 51, 52, and 53 includes a plunger 54 and a coil 55. The plunger 54 is pushed by a spring. When no current flows through the coil 55, the plunger 54 is pushed by the spring, causing the injectors 51, 52, and 53 to close. When the injectors 51, 52, and 53 are closed, no anode gas is injected from the injectors 51, 52, and 53. When a current flows through the coil 55, the plunger 54 moves against the spring, causing the injectors 51, 52, and 53 to open. When the injectors 51, 52, and 53 are open, anode gas is injected from the injectors 51, 52, and 53.

[0027] The current flowing through the coil 55 is supplied from the battery 11. The coil 55 is connected to a drive circuit 12. The drive circuit 12 is connected to the battery 11. The drive circuit 12 includes, for example, a switching element, and switches between supplying current to the coil 55 and cutting off the supply of current to the coil 55 by the switching operation of the switching element.

[0028] 1, the second connection passage 44 connects the regulator 43 and the injector assembly 50. More specifically, the second connection passage 44 connects the regulator 43 and each of the injectors 51, 52, and 53. The anode gas supplied to the injector assembly 50 is anode gas whose pressure has been reduced by the regulator 43.

[0029] The supply path 45 connects the injector assembly 50 to the anode flow path 24. More specifically, the supply path 45 connects each of the injectors 51, 52, and 53 to the inlet 25 of the anode flow path 24. The anode gas injected from the injector assembly 50 is supplied to the fuel cell stack 21 through the supply path 45.

[0030] The circulation path 46 connects the anode flow path 24 and the supply path 45. More specifically, the circulation path 46 connects the outlet 26 of the anode flow path 24 and the supply path 45. It can be said that the circulation path 46 merges with the supply path 45 downstream of the injector assembly 50. Anode exhaust gas flows through the circulation path 46. The anode exhaust gas contains unreacted anode gas and produced water. The circulation path 46 is a passage for returning the unreacted anode gas contained in the anode exhaust gas to the supply path 45.

[0031] The gas-liquid separator 47 is provided in the circulation path 46. The gas-liquid separator 47 separates the anode exhaust gas into anode gas and produced water. The produced water separated from the anode exhaust gas is stored in the gas-liquid separator 47.

[0032] The exhaust drain valve 48 is connected to the gas-liquid separator 47. The exhaust drain valve 48 can be switched between an open state and a closed state. When the exhaust drain valve 48 is in the open state, the generated water is discharged from the gas-liquid separator 47. When the exhaust drain valve 48 is in the closed state, the generated water cannot be discharged from the gas-liquid separator 47. In other words, when the exhaust drain valve 48 is in the closed state, the generated water accumulates in the gas-liquid separator 47. The exhaust drain valve 48 may be switched from the closed state to the open state when the amount of generated water accumulated in the gas-liquid separator 47 exceeds a threshold value. The exhaust drain valve 48 may be switched from the closed state to the open state at predetermined time intervals.

[0033] The gas-liquid separator 47 is connected to a diluter 61. When the exhaust / drain valve 48 is opened, the produced water stored in the gas-liquid separator 47 and the anode exhaust gas are supplied to the diluter 61. The diluter 61 dilutes the anode exhaust gas with the cathode exhaust gas and discharges it into the atmosphere.

[0034] The water storage tank 62 is connected to the diluter 61. The water storage tank 62 stores the produced water supplied from the diluter 61. The circulation pump 49 is provided in the circulation path 46. The circulation pump 49 supplies the anode gas separated from the anode exhaust gas by the gas-liquid separator 47 to the supply path 45. This causes the anode gas to circulate.

[0035] The pressure sensor 60 is provided in the supply path 45. The pressure sensor 60 detects the pressure in the supply path 45. The supply path 45, the anode flow path 24, and the circulation path 46 are connected to one another. Therefore, the supply path 45, the anode flow path 24, and the circulation path 46 can be considered to have the same pressure.

[0036] The control device 70 includes a processor 71 and a storage unit 72. The storage unit 72 includes a random access memory (RAM) and a read-only memory (ROM). The storage unit 72 stores program code or instructions configured to cause the processor 71 to execute processes. The storage unit 72, i.e., a computer-readable medium, includes any available medium accessible by a general-purpose or special-purpose computer. The control device 70 may be configured with a hardware circuit such as an ASIC or FPGA. The control device 70, which is a processing circuit, may include one or more processors that operate according to a computer program, one or more hardware circuits such as an ASIC or FPGA, or a combination thereof.

[0037] The control device 70 is configured to be able to acquire the detection results of the voltage sensor 27 , the flow meter 33 , and the pressure sensor 60 . The control device 70 controls the injector assembly 50. The control device 70 controls the drive circuit 12 to open and close the three injectors 51, 52, and 53. An opening operation means changing the injectors 51, 52, and 53 from a closed state to an open state. The opening operation of the injectors 51, 52, and 53 starts the injection of anode gas from the injectors 51, 52, and 53. A closing operation means changing the injectors 51, 52, and 53 from an open state to a closed state. The closing operation of the injectors 51, 52, and 53 stops the injection of anode gas from the injectors 51, 52, and 53. The control device 70 can individually control the three injectors 51, 52, and 53. That is, the three injectors 51, 52, and 53 can be opened or closed independently.

[0038] The control device 70 controls the power generation of the fuel cell stack 21. The control device 70 sets a target value for the amount of power generation of the fuel cell stack 21, i.e., a target value for the output of the fuel cell stack 21. The control device 70 can adjust the amount of cathode gas supplied to the fuel cell stack 21 by controlling the electric compressor 32. The control device 70 can adjust the amount of anode gas supplied to the fuel cell stack 21 by controlling the injector assembly 50. When controlling the injector assembly 50, the control device 70 may cause one of the three injectors 51, 52, and 53 to inject the anode gas. In this case, the control device 70 may sequentially switch the injectors 51, 52, and 53 that inject the anode gas, such as injector 51 → injector 52 → injector 53 → injector 51.... When controlling the injector assembly 50, the control device 70 may cause more than one of the three injectors 51, 52, and 53 to inject the anode gas. The control device 70 controls the amount of power generated by the fuel cell stack 21 so that it follows a target value.

[0039] The control device 70 can switch between operating and stopping the circulation pump 49. The control device 70 can switch between an open state and a closed state of the exhaust / drain valve 48. Next, a description will be given of the draining of water from the anode flow channel 24. The control device 70 performs the following control during the startup of the fuel cell system 20.

[0040] As shown in FIG. 3 , in step S1, the control device 70 determines whether or not water needs to be drained from the anode flow path 24. Water draining refers to discharging water from the anode flow path 24. Whether or not water needs to be drained can be determined based on the voltage of the fuel cell units 22 that make up the fuel cell stack 21. The control device 70 determines that water needs to be drained if the voltage of any of the fuel cell units 22 that make up the fuel cell stack 21 is negative. The control device 70 determines that water draining is not necessary if the voltages of all of the fuel cell units 22 that make up the fuel cell stack 21 are not negative. If the voltage of any of the fuel cell units 22 that make up the fuel cell stack 21 becomes negative despite the supply of anode gas, it is believed that the water in the anode flow path 24 is inhibiting the anode gas reaction in the fuel cell stack 21. If the determination result in step S1 is positive, i.e., if water draining is necessary, the control device 70 performs the process of step S2. If the determination result in step S1 is negative, i.e., if water draining is not necessary, the control device 70 performs the process of step S1 again. The control from step S2 onwards is water drainage control for draining water from the anode flow path 24. When performing water drainage control, the control device 70 keeps the circulation pump 49 in an operating state. When performing water drainage control, the control device 70 keeps the exhaust / drain valve 48 in a closed state.

[0041] In step S2, the control device 70 calculates a target pressure for the anode flow channel 24. The target pressure for the anode flow channel 24 is a pressure required to discharge water from the anode flow channel 24. The control device 70 calculates the target pressure for the anode flow channel 24 from the pressure detected by the pressure sensor 60. The target pressure for the anode flow channel 24 is a value higher than the pressure detected by the pressure sensor 60, for example, a value higher by a predetermined pressure than the pressure detected by the pressure sensor 60. The predetermined pressure is, for example, a value that is determined in advance.

[0042] Next, in step S3, the control device 70 calculates the injector open time T1. The injector open time T1 is the time for which the injectors 51, 52, and 53 are maintained in an open state. The injector open time T1 is the open time of the injectors 51, 52, and 53 required for the pressure in the anode flow path 24 to reach the target pressure. The injector open time T1 can be calculated, for example, from the volume of the supply path 45, the volume of the anode flow path 24, the volume of the circulation path 46, the pressure detected by the pressure sensor 60, and the pressure of the anode gas injected from the injectors 51, 52, and 53. The pressure in the second connection path 44 is maintained constant by the regulator 43. Therefore, the pressure of the anode gas injected from the injectors 51, 52, and 53 can be known in advance from the pressure in the second connection path 44. The total volume of the supply path 45, the volume of the anode flow path 24, and the volume of the circulation path 46 is constant. The control device 70 can calculate the amount of anode gas required to bring the supply path 45, the anode flow path 24, and the circulation path 46 to the target pressure, based on the pressure difference between the pressure detected by the pressure sensor 60 and the pressure of the anode gas injected from the injectors 51, 52, and 53. The control device 70 calculates the injector open time T1 so that the amount of anode gas required to bring the supply path 45, the anode flow path 24, and the circulation path 46 to the target pressure is injected from the injectors 51, 52, and 53. The control device 70 then determines the injector open time T1. Because the injector open time T1 is the time during which the injectors 51, 52, and 53 are maintained in an open state, determining the injector open time T1 can be said to be determining the operating states of the injectors 51, 52, and 53.

[0043] Next, in step S4, the control device 70 opens the first injector. This causes the first injector to start injecting anode gas. The first injector is one of the three injectors 51, 52, and 53. In this embodiment, the first injector is one of the three injectors 51, 52, and 53.

[0044] Next, in step S5, the control device 70 opens the second injector. The second injector is an injector selected from the three injectors 51, 52, and 53 and different from the first injector. The first injector and the second injector may be combined in any combination. One injector 51 of the three injectors 51, 52, and 53 may always be the first injector, and one injector 52 of the three injectors 51, 52, and 53 may always be the second injector. Each time the process of step S4 and the process of step S5 are performed, the injectors 51, 52, and 53 selected as the first injectors and the injectors 51, 52, and 53 selected as the second injectors may be switched. For example, suppose that the injector 51 is selected as the first injector and the injector 52 is selected as the second injector. In this case, in the next control cycle, injector 53 may be selected as the first injector, and injector 51 may be selected as the second injector. When the injectors 51, 52, and 53 selected as the first and second injectors are switched, it is preferable that the number of times the injectors 51, 52, and 53 perform the opening operation, i.e., the number of times the anode gas is injected, is the same for all three injectors 51, 52, and 53. The injectors 51, 52, and 53 selected as the first injectors and the injectors 51, 52, and 53 selected as the second injectors may be switched randomly. In this embodiment, the second injector is one injector selected from the three injectors 51, 52, and 53 and is different from the first injector.

[0045] The opening operation of the second injector is performed a predetermined time T2 after the opening operation of the first injector is initiated. That is, the control device 70 starts injecting anode gas by the second injector a predetermined time T2 after the first injector starts injecting anode gas. The predetermined time T2 is shorter than the injector open time T1. Therefore, the injector open time T1 can be said to be a time set so that the multiple injectors 51, 52, and 53 simultaneously inject anode gas. "The multiple injectors 51, 52, and 53 simultaneously inject anode gas" means that the multiple injectors 51, 52, and 53 are simultaneously in an open state for at least a portion of the injector open time T1. "The multiple injectors 51, 52, and 53 simultaneously inject anode gas" means that at least two injectors 51, 52, and 53 are simultaneously in an open state. The opening operation of the injectors 51, 52, and 53 is performed by passing a current through the coil 55. Therefore, when the injectors 51, 52, and 53 are opened, an inrush current flows.

[0046] As shown in Fig. 4, the time from when the opening operation of the injectors 51, 52, and 53 starts until the inrush current subsides is defined as inrush current time T3. The predetermined time T2 is set based on the inrush current time T3. For example, the predetermined time T2 may be the same as the inrush current time T3 or may be longer than the inrush current time T3. The predetermined time T2 is set based on an estimate of the inrush current time T3.

[0047] 3, in step S6, the control device 70 closes the first and second injectors when the injector open time T1 has elapsed since the start of the opening operation of the first injector. In this way, the control device 70 controls the injector assembly 50 in accordance with the injector open time T1 calculated in step S3. It can be said that the control device 70 injects anode gas from the multiple injectors 51, 52, and 53 in accordance with the operating state. After completing the processing of step S6, the control device 70 ends the water drainage control.

[0048] The operation of this embodiment will be described. As shown in FIG. 5, when draining water, the first injector is opened at time T11. At time T12, a predetermined time T2 after time T11, the second injector is opened. At time T13, an injector opening time T1 after time T11, the first and second injectors are closed. From time T12 to time T13, i.e., the injector opening time T1 minus the predetermined time T2, both the first and second injectors are open. By opening the first and second injectors, the injection amount of anode gas is increased during the injector opening time T1 compared to when a single injector is open. This makes it easier for the pressure in the anode flow channel 24 to reach the target pressure. When the pressure at the inlet 25 of the anode flow channel 24 is higher than the pressure at the outlet 26 of the anode flow channel 24, the pressure difference allows water to be discharged from the anode flow channel 24.

[0049] The effects of this embodiment will be described. (1) The control device 70 drains water from the anode flow path 24 using multiple injectors 51, 52, and 53. Compared to using a single injector to set the pressure in the anode flow path 24 to the target pressure, the number of times that each injector 51, 52, and 53 injects anode gas can be reduced. This can suppress deterioration of the injectors 51, 52, and 53 that would otherwise be caused by repeated opening operations of the injectors 51, 52, and 53. This can delay the replacement time for the injectors 51, 52, and 53.

[0050] (2) The control device 70 opens the second injector a predetermined time T2 after the start of the opening operation of the first injector. This reduces the inrush current compared to when the opening operations of multiple injectors 51, 52, and 53 are started simultaneously. The electrical circuit, including the drive circuit 12, needs to set an allowable current to prevent abnormalities caused by the inrush current. The larger the inrush current, the higher the allowable current must be increased, which can increase costs. By reducing the inrush current, there is no need to increase the allowable current, which can suppress increases in costs.

[0051] (3) The control device 70 operates the circulation pump 49 while performing the water drainage control. The circulation pump 49 supplies anode gas from the circulation path 46 to the supply path 45. Therefore, while the circulation pump 49 is operating, backflow of anode gas from the supply path 45 to the circulation path 46 via the circulation pump 49 is unlikely to occur. If backflow of anode gas from the supply path 45 to the circulation path 46 occurs during water drainage, the pressure difference between the inlet 25 and the outlet 26 becomes smaller, making it difficult for water to be discharged from the anode flow path 24. By operating the circulation pump 49 while performing the water drainage control, it is possible to prevent water from being difficult to be discharged from the anode flow path 24.

[0052] (4) The control device 70 determines the injector open time T1 as an operating state. The control device 70 then controls the injectors 51, 52, and 53 in accordance with the injector open time T1. If the injector open time T1 is set to a fixed value, each of the injectors 51, 52, and 53 may have to perform an opening operation multiple times to bring the anode flow path 24 to the target pressure. In this case, the injectors 51, 52, and 53 do not contribute to pressurizing the anode flow path 24 while they are closed, which increases the time required for water removal. By determining the injector open time T1 required to bring the anode flow path 24 to the target pressure and controlling the injectors 51, 52, and 53 accordingly, the anode flow path 24 can be brought to the target pressure without each of the injectors 51, 52, and 53 performing an opening operation multiple times. This reduces the time required for water removal.

[0053] (5) The circulation path 46 is connected to the supply path 45. The anode gas is supplied from the circulation path 46 to the supply path 45 by a circulation pump 49. Therefore, the anode gas can be circulated without providing an ejector.

[0054] The embodiment can be modified as follows: The embodiment and the following modifications can be combined with each other within the scope of technical compatibility. The control device 70 may stop the circulation pump 49 when performing the water drainage control.

[0055] When draining water, the control device 70 only needs to be able to inject anode gas from the first injector and the second injector while operating the circulation pump 49. Therefore, the control device 70 only needs to be able to keep the circulation pump 49 in operation while the first injector and the second injector are open.

[0056] The control device 70 may open the first injector and the second injector simultaneously. In this case, the time for which the first injector is maintained in the open state may be the same as the time for which the second injector is maintained in the open state. When the opening operations of the first injector and the second injector are performed simultaneously, the allowable current of the electrical circuit is set accordingly.

[0057] When draining water, the control device 70 may open all of the multiple injectors 51, 52, and 53. For example, the control device 70 may open an injector other than the first and second injectors among the three injectors 51, 52, and 53 after a predetermined time has elapsed since the start of the opening operation of the second injector. In this case, the predetermined time may be the same as or different from the predetermined time T2.

[0058] There may be two or more first injectors. As in the embodiment, assume that the injector assembly 50 includes three injectors 51, 52, and 53. In this case, two of the three injectors 51, 52, and 53 are first injectors and one is a second injector. The control device 70 opens one second injector after a predetermined time T2 has elapsed since the start of the opening operations of the two first injectors.

[0059] There may be two or more second injectors. As in the embodiment, assume that the injector assembly 50 includes three injectors 51, 52, and 53. In this case, one of the three injectors 51, 52, and 53 serves as the first injector, and the other two serve as second injectors. The control device 70 opens the two second injectors after a predetermined time T2 has elapsed since the start of the opening operation of one first injector.

[0060] The closing operation of the first injector and the closing operation of the second injector may be performed at different times. For example, the closing operation of the second injector may be performed after the injector opening time T1 has elapsed since the opening operation of the second injector. In this case, there is a predetermined time difference T2 between the time when the closing operation of the first injector is performed and the time when the closing operation of the second injector is performed.

[0061] The injector open time T1 may be a fixed value. In this case, the control device 70 determines the number of times the injectors 51, 52, and 53 are opened to bring the anode flow path 24 to the target pressure as the operating state. The control device 70 controls the injector assembly 50 so that multiple injectors 51, 52, and 53 are open according to the operating state. Even in this case, deterioration of the injectors 51, 52, and 53 can be suppressed compared to when a single injector is used to bring the anode flow path 24 to the target pressure.

[0062] The operating state may be one in which the multiple injectors 51, 52, and 53 inject anode gas, and may not simultaneously inject anode gas from the multiple injectors 51, 52, and 53. For example, during the injector open time T1, the second injector may start injecting anode gas after the first injector has finished injecting anode gas and entered a closed state.

[0063] The control device 70 may determine whether water draining is necessary based on the anode gas pressure, the cathode gas flow rate, and the amount of power generated by the fuel cell stack 21. The amount of power generated by the fuel cell stack 21 is determined by the anode gas pressure and the cathode gas flow rate. The control device 70 predicts the amount of power generated by the fuel cell stack 21 based on the anode gas pressure and the cathode gas flow rate. The control device 70 compares the predicted value of the amount of power generated by the fuel cell stack 21, calculated from the anode gas pressure and the cathode gas flow rate, with the amount of power generated by the fuel cell stack 21 obtained from the wattmeter. The wattmeter is a component for detecting the amount of power generated by the fuel cell stack 21. The control device 70 determines that water draining is necessary if the amount of power generated by the fuel cell stack 21 obtained from the wattmeter is lower than the predicted value by a predetermined value or more. The predetermined value is a predetermined value. For example, the predetermined value is set to a value that allows for a decrease in power generation due to water present in the anode flow path 24. The anode gas pressure can be obtained from the pressure sensor 60. The flow rate of the cathode gas can be obtained from the flow meter 33. The control device 70 may determine whether or not water needs to be drained from the impedance of the fuel cell stack 21. In this case, the fuel cell system 20 is provided with an impedance measuring device. [Explanation of symbols]

[0064] 20... fuel cell system, 21... fuel cell stack, 24... anode flow path, 25... inlet, 26... outlet, 45... supply path, 46... circulation path, 49... circulation pump, 50... injector assembly, 51, 52, 53... injectors, 70... control device.

Claims

1. a fuel cell stack that generates electricity by a reaction between an anode gas and a cathode gas; an injector assembly for injecting the anode gas; A fuel cell system comprising: the fuel cell stack includes an anode flow path to which the anode gas is supplied, the injector assembly includes three injectors; The fuel cell system includes: a supply passage connecting the injector assembly to the inlet of the anode flow path; a circulation path connecting the outlet of the anode flow path and the supply path, The control device determining whether or not water needs to be drained from the anode flow path; If the water drainage is required, determining an operating state of the injector assembly such that the pressure in the anode flow path reaches a target pressure, and the three injectors inject the anode gas; Injecting the anode gas into the three injectors according to the operating state; When the fuel cell stack is generating electricity, the anode gas is injected into one of the three injectors.

2. If one of the three injectors is designated as a first injector, 2. The fuel cell system according to claim 1, wherein, when causing the three injectors to inject the anode gas in accordance with the operating state, the control device starts injection of the anode gas by a second injector, which is different from the first injector, of the three injectors, after a predetermined time has elapsed since injection of the anode gas by the first injector started.

3. the fuel cell system includes a circulation pump that supplies the anode gas from the circulation path to the supply path; 3. The fuel cell system according to claim 1, wherein the control device, when injecting the anode gas from the three injectors in accordance with the operating state, causes the injectors to inject the anode gas while operating the circulation pump.

4. a fuel cell stack that generates electricity by a reaction between an anode gas and a cathode gas; an injector assembly for injecting the anode gas; A fuel cell system comprising: the fuel cell stack includes an anode flow path to which the anode gas is supplied, the injector assembly includes a plurality of injectors; The fuel cell system includes: a supply passage connecting the injector assembly to the inlet of the anode flow path; a circulation path connecting the outlet of the anode flow path and the supply path, The control device determining whether or not water needs to be drained from the anode flow path; If the water drainage is required, determining an operating state of the injector assembly such that the pressure in the anode flow path reaches a target pressure, and the operating state of the injectors such that the anode gas is injected; injecting the anode gas from the plurality of injectors according to the operating state; determining an injector open time for maintaining the plurality of injectors in an open state when determining the operating state; A fuel cell system, wherein the injector open time is a fixed value.

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