Fuel cell system

Abstract

The present application provides a technology capable of ensuring the flow rate of fuel gas supplied to a fuel cell in a fuel cell system. The fuel cell system includes a fuel cell, a fuel tank that stores fuel gas supplied to the fuel cell, a fuel gas supply path that includes a linear solenoid valve and an ejector provided on a downstream side thereof, and a control device that supplies the ejector with fuel gas at a target flow rate by controlling the operation of the linear solenoid valve. The control device is configured to selectively execute a linear control mode in which the target flow rate is achieved by maintaining the opening degree of the linear solenoid valve constant and a pulse control mode in which the target flow rate is achieved by periodically changing the opening degree of the linear solenoid valve between at least two values.

Description

Technical Field

[0001] The technology disclosed in this specification relates to fuel cell systems. Background Technology

[0002] Patent Document 1 discloses a fuel cell system. This fuel cell system includes: a fuel cell; a fuel tank for storing fuel gas supplied to the fuel cell; a fuel gas supply path having a linear solenoid valve and an ejector disposed downstream therefrom for supplying fuel gas from the fuel tank to the fuel cell; and a control device for supplying a target flow rate of fuel gas to the ejector by controlling the operation of the linear solenoid valve. The control device is configured to achieve the target flow rate by maintaining the opening of the linear solenoid valve at a constant value.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2024-012922

[0004] In the fuel cell system of Patent Document 1, fuel gas is supplied from the fuel tank to the ejector, and a portion of the exhaust gas discharged from the fuel cell is also supplied to the ejector. That is, within the ejector, the fuel gas supplied from the fuel tank mixes with a portion of the exhaust gas discharged from the fuel cell. The exhaust gas contains fuel gas at a relatively high temperature. Therefore, when the temperature of the fuel gas supplied from the fuel tank to the ejector is relatively low, the high-temperature fuel gas mixes with the low-temperature fuel gas, thereby generating ice. This ice adheres to the nozzle of the ejector. Consequently, the amount of fuel gas supplied to the ejector may be lower than the target flow rate. Summary of the Invention

[0005] The technology disclosed in this specification provides a technique for ensuring the flow rate of fuel gas supplied to the ejector in a fuel cell system.

[0006] In the first embodiment disclosed in this specification, a fuel cell system is provided. Alternatively, the fuel cell system may include: a fuel cell; a fuel tank for storing fuel gas supplied to the fuel cell; a fuel gas supply path including a linear solenoid valve and an ejector disposed downstream of the linear solenoid valve for supplying the fuel gas from the fuel tank to the fuel cell; and a control device for supplying the fuel gas to the ejector at a target flow rate by controlling the operation of the linear solenoid valve. The control device may be configured to selectively execute a linear control mode and a pulse control mode, wherein the linear control mode achieves the target flow rate by maintaining the opening of the linear solenoid valve at a constant value, and the pulse control mode achieves the target flow rate by periodically varying the opening of the linear solenoid valve between at least two values.

[0007] Based on the above structure, by executing a pulse control mode through a control device, ice adhering to the nozzle can be blown away. Therefore, in a fuel cell system, the flow rate of fuel gas supplied to the ejector can be ensured.

[0008] The second method is based on the first method described above. In the pulse control mode, the opening degree of the linear solenoid valve can be periodically changed between at least two non-zero values.

[0009] When the opening degree of the linear solenoid valve is periodically varied between at least two values, including zero, the valve spool of the linear solenoid valve sits on the valve seat whenever the opening degree becomes zero. According to this structure, in pulse control mode, the valve spool does not sit on the valve seat. Therefore, the durability of the linear solenoid valve can be improved.

[0010] The third method is based on the first or second method described above, wherein the control device can be configured to execute the pulse control mode when a first predetermined condition is met. The first predetermined condition may include at least an external air temperature lower than a predetermined temperature.

[0011] When the outside temperature is below the specified temperature, the temperature of the fuel gas inside the fuel tank is also low. As a result, ice forms inside the ejector and adheres to the ejector nozzle. By executing a pulse control mode through a control device, the ice adhering to the nozzle can be blown away. Therefore, in a fuel cell system, the flow rate of fuel gas supplied to the ejector can be ensured.

[0012] The fourth method is based on the third method described above, wherein the first specified condition may also include the current value of the fuel cell being less than a first specified value.

[0013] When the current value of the fuel cell is less than a first predetermined value, the amount of fuel gas supplied from the fuel tank to the ejector is relatively small. Therefore, it is impossible to blow away the ice adhering to the nozzle. According to the above structure, by executing a pulse control mode through a control device, the ice adhering to the nozzle can be blown away. Therefore, in the fuel cell system, the flow rate of fuel gas supplied to the ejector can be ensured.

[0014] The fifth method is based on the fourth method described above, wherein the first specified condition may further include the elapsed time from the completion of the filling of the fuel gas into the fuel tank exceeding a first specified time.

[0015] After the fuel gas has been fully filled into the fuel tank, the temperature of the fuel gas is relatively high due to the compression work. Based on the above structure, pulse control mode can be executed under conditions where the possibility of ice formation in the ejector is low. Therefore, the durability of the linear solenoid valve can be improved.

[0016] The sixth method is based on any of the first to fifth methods described above, wherein the control device can be configured to execute the pulse control mode when a second predetermined condition is met. The second predetermined condition may include the fuel cell having a current value of a second predetermined value or higher for a second predetermined time or more.

[0017] If the amount of fuel gas supplied from the fuel tank to the ejector remains relatively high, the temperature of the fuel gas temporarily decreases. In this case, ice forms in the ejector and adheres to the nozzle. According to the above structure, by executing a pulse control mode through a control device, the ice adhering to the nozzle can be blown away. Therefore, in a fuel cell system, the flow rate of fuel gas supplied to the ejector can be ensured. Attached Figure Description

[0018] Figure 1 This is a diagram showing the outline of a fuel cell system.

[0019] Figure 2 This is a diagram showing the outline of the ejector.

[0020] Figure 3 This is a flowchart illustrating the LSV control process executed by the control device.

[0021] Figure 4 It is a time-based graph representing the FC current value, etc., in LSV linear control.

[0022] Figure 5 This is a time-based graph showing the FC current value, etc., in LSV pulse control.

[0023] Figure 6 This is a time diagram showing the FC current value, etc., in the LSV pulse control of the second embodiment. Detailed Implementation

[0024] (First embodiment)

[0025] Reference Figure 1 , Figure 2 The fuel cell system 2 will be described below. The application of the fuel cell system 2 is not particularly limited. For example, the fuel cell system 2 can be a fuel cell system for mobile vehicles such as vehicles and ships, or a fuel cell system for stationary power generation equipment.

[0026] The fuel cell system 2 includes a fuel tank 4, a fuel cell 6, a hydrogen circulation system 8 for circulating hydrogen as fuel gas, an air supply system (not shown) for supplying air as oxidant gas, a control device 10, and an external temperature sensor 12. The fuel gas is hydrogen. Although not shown, the fuel cell system 2 also includes a water-cooled cooling system for cooling the fuel cell 6. Alternatively, the fuel cell system 2 may also include an air-cooled cooling system instead of a water-cooled cooling system.

[0027] Fuel cell 6 is a device that generates electricity through the chemical reaction of hydrogen and oxygen. The chemical reaction between hydrogen and oxygen produces water. A current sensor 6A is installed in fuel cell 6 to detect the current value of fuel cell 6. Hereinafter, the current value of fuel cell 6 will be recorded as "FC current value".

[0028] The hydrogen cycle system 8 includes a supply flow path 20, an exhaust flow path 22, and a recirculation flow path 24. The supply flow path 20 connects the fuel tank 4 to the fuel cell 6. The supply flow path 20 is used to supply fuel gas to the fuel gas inlet 6B of the fuel cell 6. The exhaust flow path 22 connects the fuel cell 6 to the gas-liquid separator 70 (described later). The exhaust flow path 22 is used to discharge water produced by the fuel cell 6 and exhaust gas discharged from the fuel cell 6. Hereinafter, the exhaust gas will be referred to as "fuel exhaust gas". The recirculation flow path 24 connects the gas-liquid separator 70 to the ejector 36 (described later). The recirculation flow path 24 is used to supply fuel exhaust gas to the ejector 36.

[0029] The fuel cell system 2 also includes an ejector unit 30. The ejector unit 30 includes a linear solenoid valve (LSV) 32, an injector 34, and an ejector 36. The LSV 32 and the injector 34 are arranged side-by-side in the supply flow path 20. The LSV 32 and the injector 34 adjust the supply flow rate of fuel gas at the fuel gas inlet 6B of the fuel cell 6. The ejector 36 is located downstream of the LSV 32 and the injector 34 in the supply flow path 20.

[0030] LSV32 is installed on the first branch flow path 20A, which branches off from the supply flow path 20. LSV32 regulates the flow rate of fuel gas passing through it according to the opening degree of the plunger (not shown). The construction of LSV32 is not particularly limited, and a known linear solenoid valve construction can be used. The first branch flow path 20A on the downstream side of LSV32 is connected to ejector 36.

[0031] Injector 34 is disposed on a second branch flow path 20B, which branches off from the supply flow path 20 and the first branch flow path 20A. Injector 34 is opened and closed by driving a valve spool (not shown) at a predetermined drive cycle using electromagnetic driving force or the like. The flow rate of fuel gas is adjusted according to the ratio of valve spool opening and closing time (open time / total opening and closing time, duty cycle). The construction of injector 34 is not particularly limited, and a known injector 34 construction can be used. The second branch flow path 20B downstream of injector 34 is connected to ejector 36.

[0032] like Figure 2 As shown, the ejector 36 includes a nozzle 38. The ejector 36 draws fuel exhaust gas from the circulation path 24 by means of the injection pressure of the fuel gas from the nozzle 38. Thus, the fuel exhaust gas merges with the fuel gas injected from the nozzle 38 and is supplied to the fuel cell 6 again. Alternatively, the ejector 36 may have multiple nozzles. Furthermore, the fuel cell system 2 may also have multiple ejectors 36.

[0033] A first pressure sensor 50 and a second pressure sensor 60 are disposed on the supply flow path 20. The first pressure sensor 50 is disposed upstream of the branch point of the first branch flow path 20A and the second branch flow path 20B. The first pressure sensor 50 detects the pressure in the LSV 32 and the flow path upstream of the injector 34.

[0034] The second pressure sensor 60 is disposed between the ejector 36 and the fuel gas inlet 6B of the fuel cell 6. The second pressure sensor 60 detects the pressure in the flow path downstream of the ejector 36.

[0035] The fuel cell system 2 also includes a gas-liquid separator 70, an exhaust drainage path 72, and an exhaust drainage valve 74. The gas-liquid separator 70 is connected to the downstream end of the discharge path 22, the upstream end of the circulation path 24, and the upstream end of the exhaust drainage path 72. The exhaust drainage valve 74 is located in the exhaust drainage path 72. If the exhaust drainage valve 74 is open, water is discharged through the exhaust drainage path 72. Additionally, fuel exhaust gas from the gas-liquid separator 70 is also discharged along with water through the exhaust drainage path 72.

[0036] The control device 10 is configured as a computer equipped with a processor, RAM, ROM, and other memory. The control device 10 controls the operation of each part of the fuel cell system 2 according to a program stored in the ROM, etc.

[0037] The control device 10 is connected to the current sensor 6A, the external temperature sensor 12, the first pressure sensor 50, and the second pressure sensor 60. The control device 10 uses information obtained from each sensor (6A, 12, 50, 60, etc.) to determine the target flow rate to be supplied to the fuel cell 6. The target flow rate is the sum of the tank supply flow rate from the fuel tank 4 to the fuel cell 6 via the ejector 36 and the circulating flow rate from the gas-liquid separator 70 to the fuel cell 6 via the ejector 36. In other words, the target flow rate can also be referred to as the flow rate to be supplied to the ejector 36.

[0038] The control device 10 controls the operation of the LSV 32 and the injector 34 based on the FC current value detected by the current sensor 6A. When the FC current value is less than a first predetermined current value C1 [A], the control device 10 achieves the target flow rate by operating the injector 34. Specifically, the control device 10 achieves the target flow rate by pulse-like changes in the current supplying power to the coil of the injector 34. Conversely, when the FC current value is greater than or equal to the first predetermined current value C1 [A], the control device 10 achieves the target flow rate by operating the LSV 32. The control device 10... Figure 3 The LSV control process controls the operation of LSV32. Furthermore, when the FC current value is above the first predetermined current value C1[A], the control device 10 maintains the injector 34 in the fully open state.

[0039] (LSV control processing;) Figure 3 )

[0040] Reference Figure 3 The LSV control process executed by control device 10 will be explained. The LSV control process determines whether the LSV32 operates in linear control mode or pulse control mode. When the FC current value becomes a first predetermined current value C1 [A] or higher, control device 10 begins... Figure 3 The processing.

[0041] In S10, the control device 10 determines whether the FC current value is less than the second predetermined current value C2[A]. The second predetermined current value C2[A] is a value greater than the first predetermined current value C1[A]. If the FC current value is less than the second predetermined current value C2[A] (S10: Yes), the control device 10 proceeds to S12. On the other hand, if the FC current value is not less than the second predetermined current value C2[A] (S10: No), the control device 10 proceeds to S30.

[0042] In S12, the control device 10 determines whether the outside air temperature is lower than the specified temperature T1 [°C]. If the outside air temperature is lower than the specified temperature T1 [°C] (S12: Yes), the control device 10 proceeds to S14. On the other hand, if the outside air temperature is not lower than the specified temperature T1 [°C] (S12: No), the control device 10 proceeds to S16.

[0043] In S14, the control device 10 determines whether the elapsed time since the fuel gas filling of the fuel tank 4 is completed is less than or equal to a first predetermined time t1 [seconds]. If the elapsed time is less than or equal to the first predetermined time t1 [seconds] (S14: Yes), the control device 10 proceeds to S16. On the other hand, if the elapsed time is not less than the first predetermined time t1 [seconds], that is, if the elapsed time exceeds the first predetermined time t1 [seconds] (S14: No), the control device 10 proceeds to S20.

[0044] In S16, the control device 10 decides to make the LSV32 operate in linear control mode. For example... Figure 4 As shown, the linear control mode achieves the target flow rate by maintaining the opening degree of LSV32 at a constant level. The case where the FC current value is current value C11 [A] will be explained. In this case, the control device 10 determines the target flow rate corresponding to the current value C11 [A] and determines the current value C12 [A] as the drive current value of LSV32 corresponding to the determined target flow rate. Then, the control device 10 instructs the LSV32 to the current value C12 [A]. Thus, the opening degree of LSV32 is maintained at the opening degree corresponding to the current value C12 [A]. Furthermore, the flow rate of fuel gas supplied from the fuel tank 4 and the gas-liquid separator 70 to the fuel cell 6 becomes the target flow rate. Figure 3 If S16 ends, the control device 10 returns to S10.

[0045] In addition, Figure 3 In S20, the control device 10 determines that the LSV32 operates in pulse control mode. For example... Figure 5As shown, the pulse control mode achieves the target flow rate by periodically changing the opening degree of LSV32 between two values. The control device 10 periodically changes the drive current of LSV32 between a first minimum current value Cmin1 [A] and a first maximum current value Cmax1 [A]. The first minimum current value Cmin1 [A] and the first maximum current value Cmax1 [A] are 0 [A] and 2.0 [A], respectively. Furthermore, the first minimum current value Cmin1 [A] and the first maximum current value Cmax1 [A] correspond to the minimum and maximum opening degrees of LSV32, respectively. The case where the FC current value is the current value C11 [A] will be explained. In this case, the control device 10 determines the target flow rate corresponding to the current value C11 [A]. Then, the control device 10 adds a predetermined flow rate to the target flow rate to determine the new target flow rate. Next, the control device 10 determines a control method for the LSV32 drive current to achieve the target flow rate by periodically changing the LSV drive current between a first minimum current value Cmin1 [A] and a first maximum current value Cmax1 [A]. Specifically, the control device 10 determines the ratio of the time when the LSV32 drive current is set to the first minimum current value Cmin1 [A] to the time when the LSV32 drive current is set to the first maximum current value Cmax1 [A]. Then, the control device 10 controls the LSV32 drive current. Thus, the LSV32 opening degree is periodically changed between the minimum and maximum opening degree. Furthermore, the flow rate of fuel gas supplied from the fuel tank 4 and the gas-liquid separator 70 to the fuel cell 6 becomes the target flow rate. Thus, with the same FC current value, the target flow rate in pulse control mode is greater than the target flow rate in linear control mode. Figure 3 If S20 ends, the control device 10 returns to S10.

[0046] In S30, the control device 10 determines whether the FC current value is less than a third predetermined current value C3 [A]. The third predetermined current value C3 [A] is greater than the second predetermined current value C2 [A]. If the FC current value is less than the third predetermined current value C3 [A] (S30: Yes), the control device 10 proceeds to S32. On the other hand, if the FC current value is not less than the third predetermined current value C3 [A] (S30: No), the control device 10 proceeds to S40.

[0047] S32 is the same as S16. If S32 ends, the control device 10 returns to S10.

[0048] In S40, the control device 10 determines whether the duration of the state where the FC current value is above the third predetermined current value C3 [A] is above the second predetermined time t2 [seconds]. If the duration is above the second predetermined time t2 [seconds] (S40: Yes), the control device 10 proceeds to S42. On the other hand, if the duration is not above the second predetermined time t2 [seconds] (S40: No), the control device 10 proceeds to S50.

[0049] In S42, the control device 10 determines whether the duration of the state where the FC current value is above the third predetermined current value C3 [A] is less than the third predetermined time t3 [seconds]. The third predetermined time t3 [seconds] is longer than the second predetermined time t2 [seconds]. If the duration is less than the third predetermined time t3 [seconds] (S42: Yes), the control device 10 proceeds to S44. On the other hand, if the duration is not less than the third predetermined time t3 [seconds] (S42: No), the control device 10 proceeds to S50.

[0050] S44 is the same as S20. If S44 ends, the control device 10 returns to S10.

[0051] S50 is the same as S20. If S50 ends, the control device 10 returns to S10.

[0052] In addition, the control device 10 performs Figure 3 During the processing, if the FC current value becomes less than the first specified current value C1[A], LSV32 is switched to the fully closed state, and the process ends. Figure 3 The processing.

[0053] In summary, in the low-load region where the FC current value is less than the first specified current value C1 [A], the control device 10 activates the injector 34. Furthermore, in the first medium-load region where the FC current value is greater than or equal to the first specified current value C1 [A] and less than the second specified current value C2 [A], the control device 10 activates the LSV32 in either a linear control mode or a pulse control mode. Moreover, in the second medium-load region where the FC current value is greater than or equal to the second specified current value C2 [A] and less than the third specified current value C3 [A], the control device 10 activates the LSV32 in a linear control mode. Finally, in the high-load region where the FC current value is greater than or equal to the third specified current value C3 [A], the control device 10 activates the LSV32 in either a linear control mode or a pulse control mode.

[0054] Furthermore, when either the first pulse control mode execution condition or the second pulse control mode execution condition is met, the control device 10 executes the pulse control mode; when neither the first nor the second pulse control mode execution condition is met, the control device 10 executes the linear control mode. The first pulse control mode execution condition includes the FC current value being less than the second predetermined current value C2[A]. Figure 3 The conditions for executing the second pulse control mode include: S10: Yes; the external temperature is less than the predetermined temperature T1 [°C]; S12: Yes; and the elapsed time from the completion of filling the fuel gas into the fuel tank 4 exceeds the first predetermined time t1 [seconds]; S14: No. The conditions for executing the second pulse control mode include: the FC current value being greater than or equal to the third predetermined current value C3 [A] for a second predetermined time t2 [seconds]; S30: Yes; S40: Yes; and the duration being less than the third predetermined time t3 [seconds]; S42: Yes.

[0055] As described above, the fuel cell system 2 includes: a fuel cell 6; a fuel tank 4 for storing fuel gas supplied to the fuel cell 6; a supply path 20 (an example of a "fuel gas supply path"), including an LSV 32 and an ejector 36 disposed downstream therefrom, for supplying fuel gas from the fuel tank 4 to the fuel cell 6; and a control device 10 for supplying fuel gas to the ejector 36 by controlling the operation of the LSV 32. The control device 10 is configured to selectively execute a linear control mode (…). Figure 3 S16, S32, S50) and pulse control mode ( Figure 3 (S20, S44), the linear control mode achieves the target flow rate by maintaining the opening of LSV32 at a constant value, and the pulse control mode achieves the target flow rate by periodically changing the opening of LSV32 between at least two values.

[0056] According to the above structure, by executing the pulse control mode through the control device 10, ice adhering to the nozzle 38 can be blown away. Therefore, in the fuel cell system 2, the flow rate of fuel gas supplied to the ejector 36 can be ensured.

[0057] Furthermore, the control device 10 is configured to execute a pulse control mode when a first pulse control mode execution condition (an example of a "first specified condition") is met. The first pulse control mode execution condition includes at least an external air temperature lower than a specified temperature T1 [°C]. Figure 3 S12: Yes).

[0058] When the external temperature is lower than the specified temperature T1 [°C], the temperature of the fuel gas inside the fuel tank 4 is also low. Therefore, ice forms inside the ejector 36 and adheres to the nozzle 38 of the ejector 36. By executing a pulse control mode through the control device 10, the ice adhering to the nozzle 38 can be blown away. Therefore, in the fuel cell system 2, the flow rate of fuel gas supplied to the ejector 36 can be ensured.

[0059] In addition, the execution conditions for the first pulse control mode also include that the FC current value is less than the second specified current value C2[A] (an example of the "first specified value"). Figure 3 S10: Yes).

[0060] When the FC current value is less than the second specified current value C2[A], the amount of fuel gas supplied from the fuel tank 4 to the ejector 36 is relatively small. Therefore, the ice adhering to the nozzle 38 cannot be blown away. According to the above structure, by executing the pulse control mode by the control device 10, the ice adhering to the nozzle 38 can be blown away. Therefore, in the fuel cell system 2, the flow rate of fuel gas supplied to the ejector 36 can be ensured.

[0061] In addition, the execution conditions for the first pulse control mode also include that the elapsed time from the completion of filling of fuel gas into fuel tank 4 exceeds the first predetermined time t1 [seconds] (S14: No).

[0062] After the fuel gas has been fully filled into the fuel tank 4, the temperature of the fuel gas is relatively high due to the compression work. Based on the above structure, the pulse control mode can be executed when the possibility of ice formation within the ejector 36 is low. Therefore, the durability of the LSV32 can be improved.

[0063] Furthermore, the control device 10 is configured to execute a pulse control mode when the second pulse control mode execution condition is met. This includes a state in which the FC current value is greater than or equal to a third predetermined current value C3 [A] (an example of the "second predetermined value") for a second predetermined time t2 [seconds].

[0064] If the amount of fuel gas supplied from the fuel tank 4 to the ejector 36 remains relatively high, the temperature of the fuel gas will temporarily decrease. In this case, ice will form in the ejector 36 and adhere to the nozzle 38. According to the above structure, by executing a pulse control mode by the control device 10, the ice adhering to the nozzle 38 can be blown away. Therefore, in the fuel cell system 2, the flow rate of fuel gas supplied to the ejector 36 can be ensured.

[0065] (Second Embodiment)

[0066] In the second embodiment, Figure 3The pulse control mode of LSV32 in S20 and S44 is different from the pulse control mode of LSV32 in the first embodiment.

[0067] Reference Figure 6 The pulse control mode of the LSV32 in the second embodiment will be described. The pulse control mode achieves the target flow rate by periodically changing the opening degree of the LSV32 between two values. The control device 10 periodically changes the drive current of the LSV32 between a second minimum current value Cmin2 [A] and a second maximum current value Cmax2 [A]. The second minimum current value Cmin2 [A] is a current value greater than zero and smaller than the current value used to achieve the target flow rate in the linear control mode. The second maximum current value Cmax2 [A] is a current value greater than the current value used to achieve the target flow rate in the linear control mode and smaller than the current value corresponding to the maximum opening degree of the LSV32.

[0068] The case where the FC current value is current value C11 [A] will be explained. In this case, the control device 10 determines the target flow rate corresponding to the current value C11 [A]. Next, the control device 10 determines a control method for the drive current of LSV32 that uses the average flow rate when the LSV drive current is periodically changed between the second minimum current value Cmin2 [A] and the second maximum current value Cmax2 [A] to become the target flow rate. Specifically, the control device 10 determines the ratio of the time when the drive current of LSV32 is set to the second minimum current value Cmin2 [A] to the time when the drive current of LSV32 is set to the second maximum current value Cmax2 [A]. Then, the control device 10 controls the drive current of LSV32. As a result, the opening degree of LSV32 is changed between the opening degree corresponding to the second minimum current value Cmin2 [A] and the opening degree corresponding to the second maximum current value Cmax2 [A]. Moreover, the flow rate of fuel gas supplied from the fuel tank 4 and the gas-liquid separator 70 to the fuel cell 6 becomes the target flow rate. Thus, in this embodiment, when the FC current value is the same, the target flow rate in pulse control mode is the same as the target flow rate in linear control mode.

[0069] As described above, in pulse control mode, the opening degree of LSV32 is periodically changed between at least two non-zero values.

[0070] When the opening degree of LSV32 is periodically varied between at least two values, including zero, the valve spool of LSV32 sits on the valve seat of the solenoid valve whenever the opening degree of LSV32 becomes zero. According to the above structure, in pulse control mode, the valve spool does not sit on the valve seat. Therefore, the durability of LSV32 can be improved.

[0071] The above description provides detailed examples of the technologies disclosed in this specification. However, these are merely illustrative and do not limit the scope of protection claimed in this application. The technology described in the scope of protection of this application includes technologies obtained by modifying or altering the above-described specific examples.

[0072] (First Modification) The fuel cell system 2 may also be without the injector 34. In this modification, when the FC current value is less than the first predetermined current value C1[A], the control device 10 also performs... Figure 3 S12~S20.

[0073] (Second variation) In pulse control mode, the control device 10 can also achieve the target flow rate by periodically changing the opening degree of LSV32 between three or more.

[0074] (Third variation) can be omitted Figure 3 S10~S16, S20.

[0075] (Fourth variation) can be omitted Figure 3 S12, S14, and S16. In this modified example, when the FC current value is less than the second specified current value C2[A], the control device 10 executes the pulse control mode.

[0076] (Fifth variation) The control device 10 can also be configured to execute the pulse control mode regardless of the FC current value when the external temperature is less than the specified temperature T [°C].

[0077] (Sixth variation) can be omitted Figure 3 S14. In this modified example, when the determination in S10 and S12 is "yes", the control device 10 executes the pulse control mode.

[0078] (Seventh variation) can be omitted Figure 3 S30, S40~S44, S50. In this modified example, if the control device 10 determines "no" in S10, it executes the linear control mode.

[0079] (Eighth Modification) The control device 10 may also be configured to execute both the pulse control mode of the first embodiment and the pulse control mode of the second embodiment. As an example, the control device 10 may execute the pulse control mode of the second embodiment when the elapsed time from start-up is less than a predetermined time, and execute the pulse control mode of the first embodiment when the elapsed time exceeds the predetermined time.

[0080] Furthermore, the technical elements described in this specification or drawings exert their technical usefulness individually or in various combinations, and are not limited to the combinations described in the technical solution at the time of application. Additionally, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives is itself technically useful.

[0081] [Explanation of reference numerals in the attached figures]

[0082] 2…Fuel cell system; 4…Fuel tank; 6…Fuel cell; 6A…Current sensor; 6B…Fuel gas inlet; 8…Hydrogen cycle system; 10…Control device; 12…External temperature sensor; 20…Supply path; 20A…First branch path; 20B…Second branch path; 22…Discharge path; 24…Circulation path; 30…Ejector unit; 32…LSV; 34…Injector; 36…Ejector; 38…Nozzle; 50…First pressure sensor; 60…Second pressure sensor; 70…Gas-liquid separator; 72…Exhaust drain path; 74…Exhaust drain valve.

Claims

1. A fuel cell system, wherein, have: Fuel cells; A fuel tank stores fuel gas supplied to the fuel cell; A fuel gas supply path includes a linear solenoid valve and an ejector disposed downstream of the linear solenoid valve, supplying fuel gas from the fuel tank to the fuel cell; and The control device supplies the fuel gas at a target flow rate to the ejector by controlling the operation of the linear solenoid valve. The control device is configured to selectively execute linear control mode and pulse control mode. The linear control mode achieves the target flow rate by maintaining the opening of the linear solenoid valve at a constant value. The pulse control mode achieves the target flow rate by periodically changing the opening of the linear solenoid valve between at least two values.

2. The fuel cell system according to claim 1, wherein, In the pulse control mode, the opening degree of the linear solenoid valve is periodically changed between at least two non-zero values.

3. The fuel cell system according to claim 1 or 2, wherein, The control device is configured to execute the pulse control mode when a first predetermined condition is met. The first specified condition includes at least an external temperature lower than a specified temperature.

4. The fuel cell system according to claim 3, wherein, The first specified condition also includes that the current value of the fuel cell is less than a first specified value.

5. The fuel cell system according to claim 4, wherein, The first specified condition also includes that the elapsed time from the completion of filling the fuel gas into the fuel tank exceeds a first specified time.

6. The fuel cell system according to claim 1 or 2, wherein, The control device is configured to execute the pulse control mode when a second predetermined condition is met, the second predetermined condition including that the current value of the fuel cell is above a second predetermined value for a second predetermined time or more.

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