Fuel cell system

Abstract

Provided is a fuel cell system comprising: a fuel cell; a first injection device for intermittently injecting a reaction gas to be supplied to the fuel cell; and a second injection device for continuously injecting the reaction gas. The fuel cell system includes a control unit for controlling the first injection device and the second injection device. When an output region of the fuel cell is defined as a low output region, a medium output region, and a high output region in order from a lower side to a higher side, the control unit causes the first injection device to perform injection in the low output region, causes at least one of the first injection device and the second injection device to perform injection in the medium output region, and causes the first injection device and the second injection device to perform injection simultaneously in the high output region.

Description

fuel cell system

[0001] The present disclosure relates to a fuel cell system having a fuel cell that generates electricity when supplied with a fuel gas and an oxidant gas.

[0002] Patent Document 1 discloses a fuel cell system having an injector and a linear solenoid valve as an injection device for injecting a reactant gas (gaseous fuel) to be supplied to the fuel cell.

[0003] Japanese Patent Application Laid-Open No. 2020-087520

[0004] In the fuel cell system disclosed in Patent Document 1, in the high power range of the fuel cell, the injector is stopped and only the linear solenoid valve is used for injection. However, in the high power range of the fuel cell, the flow rate of the reactant gas supplied to the fuel cell increases, so there is a risk that the size of the linear solenoid valve will have to be increased in order to increase the injection flow rate of the linear solenoid valve.

[0005] Therefore, the present disclosure has been made to solve the above-mentioned problems, and aims to provide a fuel cell system that can supply the required amount of reactant gas to the fuel cell in the high output range of the fuel cell without increasing the size of the injection device.

[0006] One form of the present disclosure made to solve the above problem is characterized in that, in a fuel cell system having a fuel cell, a first injection device that intermittently injects a reaction gas to be supplied to the fuel cell, and a second injection device that continuously injects the reaction gas, the system has a control unit that controls the first injection device and the second injection device, and when the output ranges of the fuel cell are defined as a low power range, a medium power range, and a high power range, in order from low to high, the control unit causes the first injection device to inject in the low power range, causes at least one of the first injection device and the second injection device to inject in the medium power range, and causes the first injection device and the second injection device to inject simultaneously in the high power range.

[0007] According to this aspect, in the high-power range where the amount of power generated by the fuel cell increases and the flow rate of the reactant gas supplied to the fuel cell increases, the reactant gas is injected not only from the second injector but also from the first injector. Therefore, in the high-power range, it is not necessary to increase the size of the second injector to increase the injection flow rate from the second injector. Therefore, in the high-power range, the amount of reactant gas required for power generation by the fuel cell can be supplied to the fuel cell without increasing the size of the second injector.

[0008] In the above aspect, when the medium power region is defined as a first medium power region and a second medium power region in order from low to high output of the fuel cell, it is preferable that the control unit causes the first injection device and the second injection device to inject simultaneously in the first medium power region, and causes the second injection device to inject in the second medium power region.

[0009] According to this aspect, in the first medium power range, the first injector and the second injector are simultaneously injected, and by adjusting the injection flow rate of the first injector and the injection flow rate of the second injector, the required flow rate can be more accurately ensured. Furthermore, particularly in the second medium power range, by injecting only the second injector, injection of the first injector can be stopped and the number of times the first injector is operated can be reduced, thereby improving the durability of the first injector.

[0010] In the above aspect, it is preferable that, in the high power region, the control unit adjusts the flow rate of the reactant gas supplied to the fuel cell by keeping the injection flow rate of the second injection device constant while changing the injection flow rate of the first injection device.

[0011] According to this aspect, the injection flow rate of the first injector can be finely adjusted in the high power range, so the flow rate of the reactant gas supplied to the fuel cell can be adjusted with high precision. Also, the number of times the second injector is operated can be reduced, so the durability of the second injector can be improved.

[0012] In the above aspect, it is preferable that, in the high power region, the control unit adjusts the flow rate of the reactant gas supplied to the fuel cell by keeping the injection flow rate of the first injection device constant while changing the injection flow rate of the second injection device.

[0013] According to this aspect, since the injection flow rate of the first injector is kept constant, it is possible to suppress pressure pulsations of the reactant gas generated during injection by the first injector. Also, since the number of times the first injector is operated can be reduced, it is possible to improve the durability of the first injector.

[0014] In the above aspect, it is preferable that the control unit causes the first injection device and the second injection device to inject simultaneously in the medium power region, and adjusts the flow rate of the reactant gas supplied to the fuel cell by keeping the injection flow rate of the first injection device constant while changing the injection flow rate of the second injection device in the medium power region and the high power region.

[0015] According to this aspect, the injection flow rate of the first injection device is kept constant, thereby suppressing pressure pulsations of the reactant gas generated during injection by the first injection device. Furthermore, the number of times the first injection device is operated can be reduced, thereby improving the durability of the first injection device. Furthermore, the pressure pulsations of the reactant gas generated during injection by the first injection device can be suppressed not only in the high-power range but also in a wide range including the medium-power range. Furthermore, by reducing the number of times the first injection device is operated, the durability of the first injection device can be improved.

[0016] In the above aspect, it is preferable that the fuel cell has an exhaust drain valve that controls the discharge of reaction off-gas from the fuel cell to the outside, and that the control unit causes the first injection device to inject in synchronization with the timing at which the exhaust drain valve is opened in the high-power region.

[0017] According to this aspect, in the high power range, the first injection device can compensate for the shortage of reactant gas supply flow rate to the fuel cell caused by opening the exhaust drain valve without increasing the size of the second injection device.

[0018] In the above aspect, it is preferable that the fuel cell has an exhaust drain valve that controls the discharge of reaction off-gas from the fuel cell to the outside, and that the control unit, in the high-power region, causes the second injection device to inject in synchronization with the timing at which the exhaust drain valve is opened.

[0019] According to this aspect, in the high power range, the second injection device can compensate for the shortage of reactant gas supply flow rate to the fuel cell caused by opening the exhaust drain valve without increasing the size of the first injection device.

[0020] In the above aspect, it is preferable that the fuel cell has an exhaust drain valve that controls the discharge of reaction off-gas from the fuel cell to the outside, and that the control unit causes the second injection device to inject in synchronization with the timing at which the exhaust drain valve is opened in the low output region.

[0021] According to this aspect, in the low power range, the second injection device can compensate for the shortage of reactant gas supply flow rate to the fuel cell caused by opening the exhaust drain valve without increasing the size of the first injection device.

[0022] According to the fuel cell system of the present disclosure, it is possible to supply the necessary amount of reactant gas to the fuel cell in the high output range of the fuel cell without increasing the size of the injection device.

[0023] 1 is a diagram showing a schematic configuration of a fuel cell system of the present embodiment; FIG. 1 is a diagram showing the relationship between the output of an FC stack and the supply flow rate (flow rate of hydrogen gas supplied to the FC stack) and the injection flow rate (injection flow rate of an injector or linear solenoid valve) in a first embodiment; FIG. 2 is a diagram showing the injection flow rate of an injector or linear solenoid valve and the discharge amount of an exhaust drain valve over time in a high output range in a modified example of the first embodiment; FIG. 3 is a diagram showing the injection flow rate of an injector or linear solenoid valve and the discharge amount of an exhaust drain valve over time in a low output range in modified examples of the first and second embodiments; FIG. 4 is a diagram showing the relationship between the output of an FC stack and the supply flow rate and the injection flow rate in a second embodiment; and FIG. 5 is a diagram showing the relationship between the output of an FC stack and the supply flow rate and the injection flow rate in a third embodiment.

[0024] An embodiment of a fuel cell system according to the present disclosure will now be described.

[0025] <Outline of Fuel Cell System> First, an outline of a fuel cell system 1 according to this embodiment will be described. The fuel cell system 1 is a system that is mounted on a fuel cell vehicle and supplies electric power to its drive motor (not shown).

[0026] (General Configuration of Fuel Cell System) As shown in Fig. 1, the fuel cell system 1 has an FC stack 11, a hydrogen system 12, an air system 13, and a control unit 14. The FC stack 11 is an example of the "fuel cell" of the present disclosure.

[0027] The FC stack 11 generates power by receiving a supply of fuel gas and a supply of oxidant gas. In this embodiment, the fuel gas is hydrogen gas, and the oxidant gas is air. That is, the FC stack 11 generates power by receiving a supply of hydrogen gas from the hydrogen system 12 and a supply of air from the air system 13. The power generated by the FC stack 11 is then supplied to a drive motor (not shown) via an inverter (not shown). The fuel gas and hydrogen gas are examples of "reactant gases" in this disclosure.

[0028] The hydrogen system 12 is provided on the anode side of the FC stack 11. The hydrogen system 12 includes a hydrogen supply passage 21, a hydrogen discharge passage 22, and a hydrogen circulation passage 23. The hydrogen supply passage 21 is a passage for supplying hydrogen gas from a hydrogen tank 31 to the FC stack 11. The hydrogen discharge passage 22 is a passage for discharging hydrogen gas discharged from the FC stack 11 (hereinafter referred to as "hydrogen off-gas") to the outside of the fuel cell system 1. The hydrogen circulation passage 23 is a passage for circulating at least a portion of the hydrogen off-gas from the hydrogen discharge passage 22 to the hydrogen supply passage 21. The hydrogen off-gas is an example of the "reaction off-gas" in this disclosure.

[0029] The hydrogen system 12 includes, in order from the hydrogen tank 31 side, a main stop valve 32, a pressure reducing valve 33, and a fuel supply device 34 in the hydrogen supply passage 21. The main stop valve 32 is a valve that switches between supplying and blocking hydrogen gas from the hydrogen tank 31 to the hydrogen supply passage 21. The pressure reducing valve 33 is a pressure regulating valve that reduces the pressure of hydrogen gas.

[0030] The fuel supply device 34 is a device that supplies hydrogen gas to the FC stack 11 and includes a fuel injection unit 41 and an ejector 42 .

[0031] The fuel injection unit 41 is a mechanism for injecting hydrogen gas, and in this embodiment, includes an injector 51 and a linear solenoid valve 52 as injection devices for injecting hydrogen gas. The injector 51 is an example of a "first injection device" in the present disclosure, and the linear solenoid valve 52 is an example of a "second injection device" in the present disclosure.

[0032] The injector 51 is an on-off valve (ON / OFF valve) that can control the opening of its injection port 51a only between a fully closed position and a fully open position, and intermittently injects hydrogen gas.

[0033] The linear solenoid valve 52 is a valve that opens and closes a hydrogen gas injection port 52a by driving a linear solenoid (not shown), and is a valve that continuously injects hydrogen gas. Furthermore, this linear solenoid valve 52 is a valve that can adjust the injection flow rate of hydrogen gas to a predetermined amount by controlling the opening of the injection port 52a to maintain it at a predetermined opening between a fully closed opening (opening of 100%) and a fully open opening (opening of 0%). Note that the "predetermined opening" is a value that changes depending on the operating conditions, and the "predetermined amount" is an amount that corresponds to the required amount of power generation in the FC stack 11.

[0034] The ejector 42 is provided downstream of the fuel injection unit 41 (downstream in the flow direction of hydrogen gas flowing through the hydrogen supply passage 21) and upstream of the FC stack 11 (upstream in the flow direction of hydrogen gas flowing through the hydrogen supply passage 21). The ejector 42 has an inlet 42a, an outlet 42b, and a suction port 42c.

[0035] 1, the inlet 42a is an introduction port for hydrogen gas injected from the fuel injection unit 41, and is connected to the injection port 51a of the injector 51 and the injection port 52a of the linear solenoid valve 52. The outlet 42b is a portion that discharges hydrogen gas and is connected to the FC stack 11. The suction port 42c is a portion that draws in hydrogen off-gas and is connected to the hydrogen circulation passage 23.

[0036] The ejector 42 draws hydrogen off-gas, which is discharged from the FC stack 11 to the hydrogen discharge passage 22, through the hydrogen circulation passage 23 and into the suction port 42c by using negative pressure generated by introducing hydrogen gas injected from the fuel injection unit 41 into the inlet 42a. The ejector 42 then merges the hydrogen off-gas drawn in through the suction port 42c with the hydrogen gas introduced through the inlet 42a, and circulates the combined hydrogen off-gas from the FC stack 11 through the outlet 42b. In this way, the hydrogen off-gas discharged from the FC stack 11 to the hydrogen discharge passage 22 is circulated to the FC stack 11 via the ejector 42.

[0037] Furthermore, the hydrogen system 12 has a gas-liquid separator 61 and an exhaust / drain valve 62 arranged in the hydrogen discharge passage 22. The gas-liquid separator 61 is a device that separates moisture from the hydrogen off-gas. The gas-liquid separator 61 is connected to the suction port 42c of the ejector 42 via the hydrogen circulation passage 23. The exhaust / drain valve 62 controls the discharge of the hydrogen off-gas discharged from the FC stack 11 to the outside, and is a valve that switches between discharging and blocking the hydrogen off-gas and moisture from the gas-liquid separator 61 to an air discharge passage 72 (described later) of the air system 13.

[0038] The air system 13 is provided on the cathode side of the FC stack 11. This air system 13 includes an air supply passage 71, an air discharge passage 72, and an air bypass passage 73. The air supply passage 71 is a passage for supplying air from outside the fuel cell system 1 to the FC stack 11. The air discharge passage 72 is a passage for discharging air discharged from the FC stack 11 (hereinafter referred to as "air off-gas") to outside the fuel cell system 1. The air bypass passage 73 is a passage that bypasses (detouring) the FC stack 11 and connects the air supply passage 71 and the air discharge passage 72.

[0039] The air system 13 includes, in order from the upstream side in the air supply passage 71, an air cleaner 81, a blower 82, an intercooler 83, and a supply air valve 84. The air cleaner 81 is a device that purifies air taken in from outside the fuel cell system 1. The blower 82 is a device that supplies air to the FC stack 11. The intercooler 83 is a device that cools the air. The supply air valve 84 is a valve that controls the flow rate of air supplied from the air supply passage 71 to the FC stack 11.

[0040] Furthermore, the air system 13 has an exhaust air valve 91 disposed in the air exhaust passage 72. The exhaust air valve 91 is a valve that controls the flow rate of the air off-gas that is exhausted from the FC stack 11 to the air exhaust passage 72.

[0041] Furthermore, the air system 13 includes a bypass air valve 101 disposed in the air bypass passage 73. The bypass air valve 101 is a valve that controls the flow rate of air in the air bypass passage 73.

[0042] The control unit 14 is a device having, for example, an arithmetic processing unit such as a CPU, a storage unit such as a ROM for storing control programs and control data processed by the CPU and a RAM used as various work areas for control processing, and an input / output interface unit. The control unit 14 performs various controls of the fuel cell system 1 in accordance with the control programs stored in the storage unit.

[0043] Specifically, the control unit 14 controls, for example, the operation of switching the opening of the injection nozzle 51 a of the injector 51 between fully closed and fully open, and the operation of maintaining the opening of the injection nozzle 52 a of the linear solenoid valve 52 at a predetermined opening. The control unit 14 also controls the main stop valve 32, the pressure reducing valve 33, the exhaust drain valve 62, the blower 82, the supply air valve 84, the exhaust air valve 91, the bypass air valve 101, and the like.

[0044] (Operation of Fuel Cell System) In the fuel cell system 1 configured as described above, in the hydrogen system 12, hydrogen gas supplied from the hydrogen supply passage 21 to the FC stack 11 is used for power generation in the FC stack 11 and then discharged to the outside from the FC stack 11 via the hydrogen discharge passage 22 as hydrogen off-gas, or is sucked into the ejector 42 via the hydrogen discharge passage 22 and the hydrogen circulation passage 23. In the air system 13, air supplied from the air supply passage 71 to the FC stack 11 is used for power generation in the FC stack 11 and then discharged to the outside from the FC stack 11 as air off-gas via the air discharge passage 72. Depending on the situation, in the air system 13, air supplied from the air supply passage 71 is discharged to the outside via the air bypass passage 73 and the air discharge passage 72 so as to bypass the FC stack 11.

[0045] <Regarding control of injectors and linear solenoid valves in each output range of the fuel cell> In such a fuel cell system 1, as shown in Figure 2, as the output of the FC stack 11 (i.e., the power generated by the FC stack 11) increases, i.e., as the amount of power generated by the FC stack 11 increases, the required supply flow rate of hydrogen gas to the FC stack 11 (denoted as "required flow rate" in Figure 2) increases.

[0046] Here, the output ranges of the FC stack 11 are defined as a low output range AR1, a medium output range AR2 (i.e., a first medium output range AR2-1, a second medium output range AR2-2), and a high output range AR3, in that order from low to high. The control of the injector 51 and the linear solenoid valve 52 performed in each output range will be described below. Note that in FIG. 2 and FIGS. 3 to 6, which will be described later, the injector 51 is represented as "INJ," and the linear solenoid valve 52 is represented as "LSV."

[0047] First Example First, the first example will be described.

[0048] 2, in the low output range AR1, the control unit 14 causes the injector 51 to inject while stopping the linear solenoid valve 52. Specifically, the control unit 14 increases the injection flow rate (of hydrogen gas) of the injector 51 as the required output of the FC stack 11 increases. Note that the low output range AR1 is, for example, a range of output that is less than 20% of the maximum output (100%) of the FC stack 11.

[0049] Next, in the first medium output range AR2-1, the control unit 14 causes both the injector 51 and the linear solenoid valve 52 to inject simultaneously. At this time, the control unit 14 adjusts the flow rate of hydrogen gas supplied to the FC stack 11 by changing the injection flow rate of each of the injector 51 and the linear solenoid valve 52. More specifically, as the required output of the FC stack 11 increases, the control unit 14 increases the injection flow rate of the linear solenoid valve 52 while decreasing the injection flow rate of the injector 51. Note that the first medium output range AR2-1 is, for example, a range of output that is 20% or more and less than 50% of the maximum output of the FC stack 11.

[0050] Next, in the second medium output range AR2-2, the control unit 14 causes the linear solenoid valve 52 to inject while stopping the injector 51. At this time, the control unit 14 increases the injection flow rate of the linear solenoid valve 52 as the required output of the FC stack 11 increases. Note that the second medium output range AR2-2 is, for example, a range of output that is 50% or more and less than 80% of the maximum output of the FC stack 11.

[0051] Next, in the high output range AR3, the control unit 14 simultaneously injects fuel from both the injector 51 and the linear solenoid valve 52. The high output range AR3 is, for example, a range of output power that is 80% or more of the maximum output power of the FC stack 11.

[0052] In this way, in this embodiment, in the high output range AR3 where the amount of power generated by the FC stack 11 increases and therefore the flow rate of hydrogen gas supplied to the FC stack 11 increases, hydrogen gas is injected not only from the linear solenoid valve 52 but also from the injector 51. Therefore, in the high output range AR3, there is no need to increase the size of the linear solenoid valve 52 to increase the injection flow rate from the linear solenoid valve 52. Therefore, in the high output range AR3, the amount of hydrogen gas required for power generation by the FC stack 11 can be supplied to the FC stack 11 without increasing the size of the linear solenoid valve 52.

[0053] Furthermore, in this high-power region AR3, the control unit 14 adjusts the flow rate of hydrogen gas supplied to the FC stack 11 by keeping the injection flow rate of the linear solenoid valve 52 constant while changing (i.e., adjusting) the injection flow rate of the injector 51.

[0054] Here, the injection flow rate of the injector 51 can be easily adjusted precisely. Therefore, in the high output range AR3, the injection flow rate of the injector 51 can be adjusted precisely, and the flow rate of the hydrogen gas supplied to the FC stack 11 can be adjusted with high precision. In addition, the number of times the linear solenoid valve 52 is operated (i.e., the number of times the injection port 52a is opened and closed) can be reduced, thereby improving the durability of the linear solenoid valve 52.

[0055] As a modified example, in the high power range AR3, the control unit 14 may cause the injector 51 to inject in synchronization with the timing at which the exhaust drainage valve 62 is opened, as shown in Fig. 3. That is, in Fig. 3, the injection flow rate of the injector 51 may be set to a predetermined (non-zero) amount in synchronization with the timing at which the discharge amount of the exhaust drainage valve 62 is set to a predetermined (non-zero) amount.

[0056] In this way, in the high output range AR3, the insufficient flow rate of hydrogen gas supplied to the FC stack 11 caused by opening the exhaust / drain valve 62 can be compensated for by the injector 51, without increasing the size of the linear solenoid valve 52. In other words, by opening the exhaust / drain valve 62, hydrogen off-gas is discharged to the outside, reducing the flow rate of circulated hydrogen off-gas, and the insufficient flow rate of the mixed gas of hydrogen gas and hydrogen off-gas supplied to the FC stack 11 can be compensated for by the injection of hydrogen gas by the injector 51.

[0057] As another modification, in the low output range AR1, the control unit 14 may cause the linear solenoid valve 52 to inject in synchronization with the timing at which the exhaust drain valve 62 is opened, as shown in Fig. 4. That is, in Fig. 4, the injection flow rate of the linear solenoid valve 52 may be set to a predetermined amount (not zero) in synchronization with the timing at which the discharge amount of the exhaust drain valve 62 is set to a predetermined amount (not zero).

[0058] As a result, in the low output range AR1, the linear solenoid valve 52 can compensate for the shortage of the supply flow rate of hydrogen gas to the FC stack 11 caused by opening the exhaust drainage valve 62, without increasing the size of the injector 51. In other words, by opening the exhaust drainage valve 62, hydrogen off-gas is discharged to the outside, reducing the flow rate of the circulated hydrogen off-gas, and the shortage of the flow rate of the mixed gas of hydrogen gas and hydrogen off-gas supplied to the FC stack 11 can be compensated for by the injection of hydrogen gas by the linear solenoid valve 52.

[0059] Second Embodiment Next, a second embodiment will be described. Differences from the first embodiment will be described, and descriptions of commonalities with the first embodiment will be omitted.

[0060] In this embodiment, as shown in Figure 5, in the high power range AR3, the control unit 14 simultaneously injects from both the injector 51 and the linear solenoid valve 52, but at this time, while keeping the injection flow rate of the injector 51 constant, it changes (i.e., adjusts) the injection flow rate of the linear solenoid valve 52, thereby adjusting the flow rate of hydrogen gas supplied to the FC stack 11.

[0061] In this way, the injection flow rate of the injector 51 is kept constant, thereby suppressing pressure pulsations of the hydrogen gas that occur when the injector 51 injects. In addition, the number of times the injector 51 operates can be reduced, thereby improving the durability of the injector 51.

[0062] As a modified example, the control unit 14 may cause the linear solenoid valve 52 to inject in synchronization with the timing at which the exhaust drain valve 62 is opened in the high output range AR3, as in the case of FIG. 4 described above.

[0063] As a result, in the high output range AR3, the linear solenoid valve 52 can compensate for the shortage of the supply flow rate of hydrogen gas to the FC stack 11 caused by opening the exhaust drainage valve 62, without increasing the size of the injector 51. In other words, by opening the exhaust drainage valve 62, hydrogen off-gas is discharged to the outside, reducing the flow rate of the circulated hydrogen off-gas, and the shortage of the flow rate of the mixed gas of hydrogen gas and hydrogen off-gas supplied to the FC stack 11 can be compensated for by the injection of hydrogen gas by the linear solenoid valve 52.

[0064] Also, in this embodiment, as another modified example, in the low output range AR1, the control unit 14 may cause the linear solenoid valve 52 to inject fuel in synchronization with the timing at which the exhaust drain valve 62 is opened, as shown in Figure 4.

[0065] Third Embodiment Next, a third embodiment will be described. Differences from the first and second embodiments will be described, and descriptions of commonalities with the first and second embodiments will be omitted.

[0066] In this embodiment, as shown in FIG. 6, in the medium output range AR2 (i.e., the first medium output range AR2-1 and the second medium output range AR2-2) and the high output range AR3, where the required supply flow rate is greater than the injection flow rate of the injector 51 when the opening of the injection port 51a is fully open, the control unit 14 causes both the injector 51 and the linear solenoid valve 52 to inject simultaneously.

[0067] At this time, the opening of the injection port 51a is set to the fully open position to keep the injection flow rate of the injector 51 constant, while the opening of the injection port 52a is changed to change (i.e., adjust) the injection flow rate of the linear solenoid valve 52, thereby adjusting the flow rate of hydrogen gas supplied to the FC stack 11.

[0068] In this way, in the medium power range AR2 and the high power range AR3, hydrogen gas is injected not only from the linear solenoid valve 52 but also from the injector 51. Therefore, in the medium power range AR2 and the high power range AR3, it is not necessary to increase the size of the linear solenoid valve 52 and the injection flow rate from the linear solenoid valve 52. Therefore, in the medium power range AR2 and the high power range AR3, it is possible to supply the amount of hydrogen gas necessary for power generation by the FC stack 11 to the FC stack 11 without increasing the size of the linear solenoid valve 52.

[0069] Furthermore, since the injection flow rate of the injector 51 is kept constant, it is possible to suppress pressure pulsations of the hydrogen gas that occur when the injector 51 injects, and since the number of times the injector 51 operates can be reduced, it is possible to improve the durability of the injector 51. This makes it possible to suppress pressure pulsations of the hydrogen gas that occur when the injector 51 injects, not only in the high power range AR3 but also in a wide range including the medium power range AR2, and also improves the durability of the injector 51 by reducing the number of times the injector 51 operates.

[0070] As a variant, the control unit 14 may inject the linear solenoid valve 52 in synchronization with the timing at which the exhaust drain valve 62 is opened, in at least one of the low power range AR1, the medium power range AR2, and the high power range AR3, in the same manner as in Figure 4 above.

[0071] It should be noted that the above-described embodiments are merely examples and do not limit the present disclosure in any way. It goes without saying that various improvements and modifications are possible within the scope of the gist of the present disclosure.

[0072] REFERENCE SIGNS LIST 1 fuel cell system 11 FC stack 12 hydrogen system 13 air system 14 control unit 21 hydrogen supply passage 22 hydrogen discharge passage 23 hydrogen circulation passage 31 hydrogen tank 34 fuel supply device 41 fuel injection unit 42 ejector 42c suction port 51 injector (INJ) 52 linear solenoid valve (LSV) 62 exhaust drain valve AR1 low power range AR2 medium power range AR2-1 first medium power range AR2-2 second medium power range AR3 high power range

Claims

1. In a fuel cell system having a fuel cell, a first injection device for intermittently injecting a reaction gas supplied to the fuel cell, and a second injection device for continuously injecting the reaction gas, the fuel cell system having a control unit for controlling the first injection device and the second injection device, when defining the output region of the fuel cell in order from the lower side to the higher side as a low output region, a medium output region, and a high output region, the control unit: in the low output region, causes the first injection device to inject; in the medium output region, causes at least one of the first injection device and the second injection device to inject; and in the high output region, causes the first injection device and the second injection device to inject simultaneously. A fuel cell system characterized by the above.

2. In the fuel cell system according to claim 1, when defining the medium output region in order from the lower side to the higher side of the output of the fuel cell as a first medium output region and a second medium output region, the control unit: in the first medium output region, causes the first injection device and the second injection device to inject simultaneously; and in the second medium output region, causes the second injection device to inject. A fuel cell system characterized by the above.

3. In the fuel cell system according to claim 1 or 2, the control unit: in the high output region, while keeping the injection flow rate of the second injection device constant, adjusts the flow rate of the reaction gas supplied to the fuel cell by changing the injection flow rate of the first injection device. A fuel cell system characterized by the above.

4. In the fuel cell system according to claim 1 or 2, the control unit: in the high output region, while keeping the injection flow rate of the first injection device constant, adjusts the flow rate of the reaction gas supplied to the fuel cell by changing the injection flow rate of the second injection device. A fuel cell system characterized by the above.

5. In the fuel cell system according to claim 1, the control unit: in the medium output region, causes the first injection device and the second injection device to inject simultaneously; and in the medium output region and the high output region, while keeping the injection flow rate of the first injection device constant, adjusts the flow rate of the reaction gas supplied to the fuel cell by changing the injection flow rate of the second injection device. A fuel cell system characterized by the above.

6. In the fuel cell system according to claim 1 or 2, having an exhaust and drainage valve for controlling the discharge of the reaction off-gas discharged from the fuel cell to the outside, the control unit causes the first injection device to inject in synchronization with the timing of opening the exhaust and drainage valve in the high output region. A fuel cell system characterized by the above.

7. In the fuel cell system according to claim 1 or 2, having an exhaust and drainage valve for controlling the discharge of the reaction off-gas discharged from the fuel cell to the outside, the control unit causes the second injection device to inject in synchronization with the timing of opening the exhaust and drainage valve in the high output region. A fuel cell system characterized by the above.

8. In the fuel cell system according to claim 1 or 2, having an exhaust and drainage valve for controlling the discharge of the reaction off-gas discharged from the fuel cell to the outside, the control unit causes the second injection device to inject in synchronization with the timing of opening the exhaust and drainage valve in the low output region. A fuel cell system characterized by the above.

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