Fuel cell system

Abstract

This invention provides a technology that can ensure the flow rate of fuel gas supplied to a fuel cell in a fuel cell system. [Solution] The fuel cell system comprises a fuel cell, a fuel tank for storing fuel gas supplied to the fuel cell, a linear solenoid valve and an ejector provided downstream thereof, a fuel gas supply path for supplying fuel gas from the fuel tank to the fuel cell, and a control device that supplies 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 a linear control mode that achieves the target flow rate by maintaining a constant opening of the linear solenoid valve, and a pulse control mode that achieves the target flow rate by periodically changing the opening of the linear solenoid valve between at least two values.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a fuel cell system.

Background Art

[0002] Patent Document 1 discloses a fuel cell system. This fuel cell system includes a fuel cell, a fuel tank that stores fuel gas supplied to the fuel cell, a linear solenoid valve, and an ejector provided downstream of the linear solenoid valve, and includes a fuel gas supply path that supplies fuel gas from the fuel tank to the fuel cell, and a control device that supplies fuel gas with a target flow rate to the ejector by controlling the operation of the linear solenoid valve. The control device is configured to realize the target flow rate by maintaining the opening degree of the linear solenoid valve constant.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the fuel cell system of Patent Document 1, fuel gas is supplied from the fuel tank to the ejector, and a part of the exhaust gas discharged from the fuel cell is supplied to the ejector. That is, in the ejector, the fuel gas supplied from the fuel tank to the ejector and a part of the exhaust gas discharged from the fuel cell are mixed. The temperature of the fuel gas contained in the exhaust gas is relatively high. Therefore, when the temperature of the fuel gas supplied from the fuel tank to the ejector is relatively low, ice is generated by mixing the high-temperature fuel gas and the low-temperature fuel gas. This ice adheres to the nozzle of the ejector. As a result, there is a possibility that the supply amount of the fuel gas supplied to the ejector may fall below the target flow rate.

[0005] The technology disclosed herein provides a technology that can ensure the flow rate of fuel gas supplied to an ejector in a fuel cell system. [Means for solving the problem]

[0006] In a first aspect disclosed herein, a fuel cell system is disclosed. The fuel cell system may include a fuel cell, a fuel tank for storing fuel gas to be supplied to the fuel cell, a linear solenoid valve and an ejector provided downstream thereof, a fuel gas supply path for supplying the fuel gas from the fuel tank to the fuel cell, and a control device for supplying a target flow rate of the fuel gas to the ejector by controlling the operation of the linear solenoid valve. The control device may be configured to selectively perform a linear control mode that achieves the target flow rate by maintaining a constant opening of the linear solenoid valve, and a pulse control mode that achieves the target flow rate by periodically changing the opening of the linear solenoid valve between at least two values.

[0007] With the above configuration, the control device can blow away ice adhering to the nozzle by executing a pulse control mode. This ensures a sufficient flow rate of fuel gas supplied to the ejector in the fuel cell system.

[0008] In a second embodiment, in the first embodiment, the opening degree of the linear solenoid valve may be periodically changed between at least two non-zero values ​​in the pulse control mode.

[0009] When the opening of a linear solenoid valve is periodically changed between at least two values, including zero, the valve body of the linear solenoid valve seats on the valve seat each time the opening of the linear solenoid valve becomes zero. According to the above configuration, in pulse control mode, the valve body does not seat on the valve seat. Therefore, the durability of the linear solenoid valve can be improved.

[0010] In a third embodiment, in the first or second embodiment, the control device may be configured to execute the pulse control mode when a first predetermined condition is met. The first predetermined condition may include, at a minimum, that the ambient temperature is below a predetermined temperature.

[0011] When the ambient temperature is below a predetermined temperature, the temperature of the fuel gas in the fuel tank is also low. As a result, ice forms inside the ejector and adheres to the ejector nozzle. The control device can blow away the ice attached to the nozzle by executing a pulse control mode. This ensures that the flow rate of fuel gas supplied to the ejector in the fuel cell system is maintained.

[0012] In a fourth embodiment, the first predetermined condition in the third embodiment may further include the current value of the fuel cell being less than the first predetermined 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 not possible to blow away the ice adhering to the nozzle. With the above configuration, the control device can blow away the ice adhering to the nozzle by executing a pulse control mode. Therefore, in the fuel cell system, it is possible to ensure a sufficient flow rate of fuel gas supplied to the ejector.

[0014] In a fifth embodiment, the first predetermined condition in the fourth embodiment may further include the fact that the elapsed time since the completion of filling the fuel tank with the fuel gas exceeds the first predetermined time.

[0015] Immediately after the fuel tank has been filled with fuel gas, the temperature of the fuel gas is relatively high due to the compression work. The above configuration makes it possible to suppress the execution of the pulse control mode in situations where ice formation in the ejector is unlikely. Therefore, the durability of the linear solenoid valve can be improved.

[0016] In the sixth aspect, in any one of the first to fifth aspects, the control device may be configured to execute the pulse control mode when a second predetermined condition is met. The second predetermined condition may include the state in which the current value of the fuel cell is equal to or greater than a second predetermined value for a period of time or longer.

[0017] If the amount of fuel gas supplied from the fuel tank to the ejector remains relatively high for an extended period, the temperature of the fuel gas will temporarily drop. In this case, ice will form in the ejector and adhere to the nozzle. With the above configuration, the control device can blow away the ice adhering to the nozzle by executing a pulse control mode. Therefore, in the fuel cell system, the flow rate of fuel gas supplied to the ejector can be ensured. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram of a fuel cell system. [Figure 2] This is a schematic diagram of an ejector. [Figure 3] This diagram shows a flowchart of the LSV control process performed by the control device. [Figure 4] This figure shows a time chart of FC current values ​​and other parameters in LSV linear control. [Figure 5] This figure shows a time chart of FC current values ​​and other parameters in LSV pulse control. [Figure 6] This figure shows a time chart of FC current values, etc., in LSV pulse control according to the second embodiment. [Modes for carrying out the invention]

[0019] (First embodiment) Referring to FIGS. 1 and 2, the fuel cell system 2 will be described. The use of the fuel cell system 2 is not particularly limited. For example, the fuel cell system 2 may be a mobile fuel cell system mounted on a mobile object such as a vehicle or a ship, or may be a stationary fuel cell system adopted for a stationary power generation facility.

[0020] The fuel cell system 2 includes a fuel tank 4, a fuel cell 6, a hydrogen circulation system 8 in which hydrogen as a fuel gas circulates, an air supply system (not shown) that supplies air as an oxidant gas, a control device 10, and an outside air temperature sensor 12. The fuel gas is hydrogen gas. Although not shown, the fuel cell system 2 further includes a water-cooled cooling system for cooling the fuel cell 6. Note that the fuel cell system 2 may include an air-cooled cooling system instead of the water-cooled cooling system.

[0021] The fuel cell 6 is a device that generates electric power by the chemical reaction between hydrogen and oxygen. When hydrogen and oxygen chemically react, water is generated. The fuel cell 6 is provided with a current sensor 6A that detects the current value of the fuel cell 6. Hereinafter, the current value of the fuel cell 6 will be referred to as the "FC current value".

[0022] The hydrogen circulation system 8 includes a supply flow path 20, a discharge flow path 22, and a circulation flow path 24. The supply flow path 20 connects the fuel tank 4 and the fuel cell 6. The supply flow path 20 is a flow path for supplying fuel gas to the fuel gas inlet 6B of the fuel cell 6. The discharge flow path 22 connects the fuel cell 6 and a gas-liquid separator 70 described later. The discharge flow path 22 is a flow path for discharging the water generated in the fuel cell 6 and the exhaust gas discharged from the fuel cell 6. Hereinafter, the exhaust gas will be referred to as "fuel off-gas". The circulation flow path 24 connects the gas-liquid separator 70 and an ejector 36 described later. The circulation flow path 24 is a flow path for supplying the fuel off-gas to the ejector 36.

[0023] The fuel cell system 2 further includes an ejector unit 30. The ejector unit 30 comprises a linear solenoid valve (LSV) 32, an injector 34, and an ejector 36. The LSV 32 and the injector 34 are arranged in parallel in the supply channel 20. The LSV 32 and the injector 34 adjust the fuel gas supply flow rate 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 channel 20.

[0024] The LSV32 is located on the first branch channel 20A, which branches off from the supply channel 20. The LSV32 adjusts the flow rate of fuel gas passing through it according to the opening of a plunger (not shown). The structure of the LSV32 is not particularly limited, and a known linear solenoid valve structure can be adopted. The first branch channel 20A downstream of the LSV32 is connected to the ejector 36.

[0025] The injector 34 is located on a second branch channel 20B that branches off from the supply channel 20 separately from the first branch channel 20A. The injector 34 is opened and closed by a valve body (not shown) which is driven by an electromagnetic drive force or the like at a predetermined drive cycle. The flow rate of the fuel gas is adjusted by the ratio of the time the valve body is open and closed (open time / total time of open and closed time, duty cycle). The structure of the injector 34 is not particularly limited, and a known injector 34 structure can be adopted. The second branch channel 20B downstream of the injector 34 is connected to the ejector 36.

[0026] As shown in Figure 2, the ejector 36 is equipped with a nozzle 38. The ejector 36 draws in fuel off-gas from the circulation channel 24 by the injection pressure of fuel gas from the nozzle 38. As a result, the fuel off-gas merges with the fuel gas injected from the nozzle 38 and is supplied again to the fuel cell 6. The ejector 36 may be equipped with multiple nozzles. The fuel cell system 2 may also be equipped with multiple ejectors 36.

[0027] A first pressure sensor 50 and a second pressure sensor 60 are provided on the supply channel 20. The first pressure sensor 50 is provided upstream of the branching point between the first branch channel 20A and the second branch channel 20B. The first pressure sensor 50 detects the pressure in the channel upstream of the LSV 32 and the injector 34.

[0028] The second pressure sensor 60 is located 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.

[0029] The fuel cell system 2 further includes a gas-liquid separator 70, an exhaust drainage channel 72, and an exhaust drainage valve 74. The gas-liquid separator 70 is connected to the downstream end of the discharge channel 22, the upstream end of the circulation channel 24, and the upstream end of the exhaust drainage channel 72. The exhaust drainage valve 74 is located in the exhaust drainage channel 72. When the exhaust drainage valve 74 opens, water is discharged through the exhaust drainage channel 72. In addition, the fuel off-gas from the gas-liquid separator 70 is also discharged through the exhaust drainage channel 72 along with the water.

[0030] The control device 10 is configured as a computer equipped with a processor and memory such as RAM and ROM. The control device 10 controls the operation of each part of the fuel cell system 2 according to a program stored in ROM or the like.

[0031] The control device 10 is connected to the current sensor 6A, the ambient 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 supplied from the fuel tank 4 to the fuel cell 6 via the ejector 36, and the circulating flow rate supplied 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 described as the flow rate to be supplied to the ejector 36.

[0032] 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. The control device 10 achieves the target flow rate by operating the injector 34 when the FC current value is less than a first predetermined current value C1 [A]. Specifically, the control device 10 achieves the target flow rate by changing the current supplied to the coil of the injector 34 in a pulsed manner. The control device 10 also achieves the target flow rate by operating the LSV 32 when the FC current value is equal to or greater than the first predetermined current value C1 [A]. The control device 10 controls the operation of the LSV 32 according to the LSV control process shown in Figure 3. The control device 10 maintains the injector 34 in a fully open state when the FC current value is equal to or greater than the first predetermined current value C1 [A].

[0033] (LSV control process; Figure 3) Referring to Figure 3, the LSV control process performed by the control device 10 will be described. The LSV control process is a process for determining whether to operate the LSV 32 in linear control mode or pulse control mode. The control device 10 starts the process shown in Figure 3 when the FC current value becomes equal to or greater than the first predetermined current value C1 [A].

[0034] 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 greater than the first predetermined current value C1[A]. If the FC current value is less than the second predetermined current value C2[A] (YES in S10), 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] (NO in S10), the control device 10 proceeds to S30.

[0035] In S12, the control device 10 determines whether the ambient temperature is below a predetermined temperature T1 [°C]. If the ambient temperature is below the predetermined temperature T1 [°C] (YES in S12), the control device 10 proceeds to S14. On the other hand, if the ambient temperature is not below the predetermined temperature T1 [°C] (NO in S12), the control device 10 proceeds to S16.

[0036] In S14, the control device 10 determines whether the elapsed time since the completion of filling the fuel tank 4 with fuel gas is less than or equal to the first predetermined time t1 [seconds]. If the elapsed time is less than or equal to the first predetermined time t1 [seconds] (YES in S14), 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] (NO in S14), the control device 10 proceeds to S20.

[0037] In S16, the control device 10 decides to operate the LSV32 in linear control mode. As shown in Figure 4, the linear control mode is a mode that achieves the target flow rate by maintaining a constant opening of the LSV32. Let's explain the case where the FC current value is current value C11[A]. 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 the LSV32 corresponding to the determined target flow rate. Next, the control device 10 commands the LSV32 to use the current value C12[A]. As a result, the opening of the LSV32 is maintained at the opening corresponding to the current value C12[A]. Then, 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. When S16 in Figure 3 is completed, the control device 10 returns to S10.

[0038] Furthermore, in S20 of Figure 3, the control device 10 decides to operate the LSV32 in pulse control mode. As shown in Figure 5, the pulse control mode is a mode that 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 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 2.0[A] and 0[A], respectively. Also, the first minimum current value Cmin1[A] and the first maximum current value Cmax1[A] correspond to the minimum opening degree and the maximum opening degree of the 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]. Next, the control device 10 adds a predetermined flow rate to the target flow rate to determine a new target flow rate. Next, the control device 10 determines a method for controlling the drive current of the LSV 32 such that the average flow rate when the LSV drive current is periodically changed between a first minimum current value Cmin1[A] and a first maximum current value Cmax1[A] becomes the target flow rate. Specifically, the control device 10 determines the ratio of the time when the drive current of the LSV 32 is at the first minimum current value Cmin1[A] to the time when the drive current of the LSV 32 is at the first maximum current value Cmax1[A]. Next, the control device 10 controls the drive current of the LSV 32. As a result, the opening degree of the LSV 32 is periodically changed between the minimum opening degree and the maximum opening degree. Then, 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, when the FC current value is the same, the target flow rate in pulse control mode is greater than the target flow rate in linear control mode. When S20 in Figure 3 is completed, the control device 10 returns to S10.

[0039] In S30, the control device 10 determines whether the FC current value is less than the 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] (YES in S30), 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] (NO in S30), the control device 10 proceeds to S40.

[0040] S32 is the same as S16. When S32 is finished, the control device 10 returns to S10.

[0041] In S40, the control device 10 determines whether the duration of the state in which the FC current value is equal to or greater than the third predetermined current value C3 [A] is equal to or greater than the second predetermined time t2 [seconds]. If the duration is equal to or greater than the second predetermined time t2 [seconds] (YES in S40), the control device 10 proceeds to S42. On the other hand, if the duration is not equal to or greater than the second predetermined time t2 [seconds] (NO in S40), the control device 10 proceeds to S50.

[0042] In S14, the control device 10 determines whether the duration of the state in which the FC current value is equal to or greater than 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] (YES in S42), the control device 10 proceeds to S44. On the other hand, if the duration is not less than the third predetermined time t3 [seconds] (NO in S42), the control device 10 proceeds to S50.

[0043] S44 is the same as S20. When S44 is finished, the control device 10 returns to S10.

[0044] S50 is the same as S20. When S50 is finished, the control device 10 returns to S10.

[0045] Furthermore, while the control device 10 is executing the process shown in Figure 3, if the FC current value falls below the first predetermined current value C1[A], it will switch the LSV32 to the fully closed state and terminate the process shown in Figure 3.

[0046] In summary, the control device 10 operates the injector 34 in the low-load region where the FC current value is less than the first predetermined current value C1[A]. In the first medium-load region where the FC current value is greater than or equal to the first predetermined current value C1[A] and less than the second predetermined current value C2[A], the control device 10 operates the LSV32 in either the linear control mode or the pulse control mode. Furthermore, in the second medium-load region where the FC current value is greater than or equal to the second predetermined current value C2[A] and less than the third predetermined current value C3[A], the control device 10 operates the LSV32 in the linear control mode. In the high-load region where the FC current value is greater than or equal to the third predetermined current value C3[A], the control device 10 operates the LSV32 in either the linear control mode or the pulse control mode.

[0047] Furthermore, the control device 10 executes the pulse control mode when the first pulse control mode execution condition or the second pulse control mode execution condition is met, and executes the linear control mode when neither the first pulse control mode execution condition nor the second pulse control mode execution condition is met. The first pulse control mode execution condition includes that the FC current value is less than the second predetermined current value C2 [A] (YES in S10 of Figure 3), the ambient temperature is less than the predetermined temperature T1 [°C] (YES in S12), and the elapsed time since the completion of filling the fuel tank 4 with fuel gas exceeds the first predetermined time t1 [seconds] (NO in S14). The second pulse control mode execution condition includes that the state in which the FC current value is 3 or more than the third predetermined current value C3 [A] continues for a second predetermined time t2 [seconds] (YES in S30, YES in S40), and that this duration is less than the third predetermined time t3 [seconds] (YES in S42).

[0048] As described above, the fuel cell system 2 includes a fuel cell 6, a fuel tank 4 in which fuel gas supplied to the fuel cell 6 is stored, an LSV 32 and an ejector 36 provided downstream of it, a supply channel 20 (an example of a "fuel gas supply channel") that supplies fuel gas from the fuel tank 4 to the fuel cell 6, and a control device 10 that supplies fuel gas at a target flow rate 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 (S16, S32, S50 in Figure 3) that achieves the target flow rate by maintaining a constant opening of the LSV 32, and a pulse control mode (S20, S44 in Figure 3) that achieves the target flow rate by periodically changing the opening of the LSV 32 between at least two values.

[0049] With the above configuration, the control device 10 can execute a pulse control mode to blow away the ice adhering to the nozzle 38. This ensures that the fuel gas flow rate supplied to the ejector 36 in the fuel cell system 2 is maintained.

[0050] Furthermore, the control device 10 is configured to execute a pulse control mode when a first pulse control mode execution condition (an example of the "first predetermined condition") is met. The first pulse control mode execution condition includes at least the condition that the ambient temperature is less than a predetermined temperature T1 [°C] (YES in S12 of Figure 3).

[0051] When the ambient temperature is below a predetermined temperature T1 [°C], the temperature of the fuel gas in the fuel tank 4 is also low. As a result, ice forms inside the ejector 36, and the ice adheres to the nozzle 38 of the ejector 36. The control device 10 can blow away the ice adhering to the nozzle 38 by executing a pulse control mode. As a result, the fuel cell system 2 can ensure a sufficient flow rate of fuel gas supplied to the ejector 36.

[0052] Furthermore, the execution condition for the first pulse control mode also includes the condition that the FC current value is less than the second predetermined current value C2[A] (an example of the "first predetermined value") (YES in S10 of Figure 3).

[0053] When the FC current value is less than the second predetermined current value C2[A], the amount of fuel gas supplied from the fuel tank 4 to the ejector 36 is relatively small. As a result, it is not possible to blow away the ice adhering to the nozzle 38. With the above configuration, the control device 10 can blow away the ice adhering to the nozzle 38 by executing a pulse control mode. As a result, the fuel cell system 2 can ensure a sufficient flow rate of fuel gas supplied to the ejector 36.

[0054] Furthermore, the execution conditions for the first pulse control mode include the fact that the elapsed time since the completion of filling the fuel tank 4 with fuel gas exceeds the first predetermined time t1 [seconds] (NO in S14).

[0055] Immediately after the fuel tank 4 has been filled with fuel gas, the temperature of the fuel gas is relatively high due to the compression work. With the above configuration, it is possible to suppress the execution of the pulse control mode in situations where there is little possibility of ice formation in the ejector 36. Therefore, the durability of the LSV 32 can be improved.

[0056] Furthermore, the control device 10 is configured to execute the pulse control mode when the second pulse control mode execution condition is met. This condition includes the state in which the FC current value is equal to or greater than the third predetermined current value C3 [A] (an example of the "second predetermined value") for a second predetermined time t2 [seconds].

[0057] 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 drop. In this case, ice will form in the ejector 36 and adhere to the nozzle 38. With the above configuration, the control device 10 can blow away the ice adhering to the nozzle 38 by executing a pulse control mode. Therefore, the fuel cell system 2 can ensure a sufficient flow rate of fuel gas supplied to the ejector 36.

[0058] (Second example) In the second embodiment, the pulse control mode of the LSV32 in S20 and S44 of Figure 3 is different from the pulse control mode of the LSV32 in the first embodiment.

[0059] Referring to Figure 6, the pulse control mode of the LSV32 in the second embodiment will be described. The pulse control mode is a mode in which the target flow rate is achieved 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 required 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 required 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.

[0060] 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 method for controlling the drive current of the LSV 32 such that the average flow rate when the LSV drive current is periodically changed between a second minimum current value Cmin2[A] and a second maximum current value Cmax2[A] becomes the target flow rate. Specifically, the control device 10 determines the ratio of the time when the drive current of the LSV 32 is set to the second minimum current value Cmin2[A] and the time when the drive current of the LSV 32 is set to the second maximum current value Cmax2[A]. Next, the control device 10 controls the drive current of the LSV 32. As a result, the opening degree of the LSV 32 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]. Then, 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 and the target flow rate in linear control mode are the same.

[0061] As described above, in pulse control mode, the opening of LSV32 is periodically changed between at least two non-zero values.

[0062] If the opening degree of the LSV32 is periodically changed between at least two values, including zero, then each time the opening degree of the LSV32 becomes zero, the valve body of the LSV32 seats on the valve seat of the solenoid valve. According to the above configuration, in pulse control mode, the valve body does not seat on the valve seat. Therefore, the durability of the LSV32 can be improved.

[0063] The specific examples of the technology disclosed in this specification have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples described above.

[0064] (First modified example) The fuel cell system 2 does not need to be equipped with an injector 34. In this modified example, the control device 10 executes S12 to S20 in Figure 3 even when the FC current value is less than the first predetermined current value C1 [A].

[0065] (Second modified example) In pulse control mode, the control device 10 may achieve the target flow rate by periodically changing the opening degree of the LSV 32 between three or more intervals.

[0066] (Third modified example) Steps S10 to S16 and S20 in Figure 3 can be omitted.

[0067] (Fourth Modification) Steps S12, S14, and S16 in Figure 3 can be omitted. In this modification, the control device 10 executes pulse control mode when the FC current value is less than the second predetermined current value C2 [A].

[0068] (Fifth Modification) The control device 10 may be configured to execute pulse control mode when the ambient temperature is below a predetermined temperature T [°C], regardless of the FC current value.

[0069] (Sixth Modification) S14 in Figure 3 can be omitted. In this modification, the control device 10 executes pulse control mode when it is determined that S10 and S12 are YES.

[0070] (Seventh Modification) Steps S30, S40-S44, and S50 in Figure 3 can be omitted. In this modification, the control device 10 executes linear control mode when NO is determined in S10.

[0071] (Eighth Modification) The control device 10 may be configured to execute both the pulse control mode according to the first embodiment and the pulse control mode according to the second embodiment. For example, the control device 10 may execute the pulse control mode according to the second embodiment when the elapsed time since startup is less than or equal to a predetermined time, and execute the pulse control mode according to the first embodiment when the elapsed time exceeds the predetermined time.

[0072] Furthermore, the technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of symbols]

[0073] 2: Fuel cell system, 4: Fuel tank, 6: Fuel cell, 6A: Current sensor, 6B: Fuel gas inlet, 8: Hydrogen circulation system, 10: Control device, 12: Ambient temperature sensor, 20: Supply channel, 20A: First branch channel, 20B: Second branch channel, 22: Discharge channel, 24: Circulation channel, 30: Ejector unit, 34: Injector, 36: Ejector, 38: Nozzle, 50: First pressure sensor, 60: Second pressure sensor, 70: Gas-liquid separator, 72: Exhaust drain channel, 74: Exhaust drain valve

Claims

1. A fuel cell system, Fuel cells and A fuel tank in which fuel gas to be supplied to the fuel cell is stored, A fuel gas supply path comprising a linear solenoid valve and an ejector provided downstream thereof, which supplies the fuel gas from the fuel tank to the fuel cell, A control device that supplies the fuel gas to the ejector at a target flow rate by controlling the operation of the linear solenoid valve, comprising: The control device is A linear control mode is achieved by maintaining a constant opening of the linear solenoid valve, and The system is configured to selectively perform a pulse control mode that achieves the target flow rate by periodically changing the opening degree of the linear solenoid valve between at least two values. Fuel cell system.

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 control device is configured to execute the pulse control mode when a first predetermined condition is met. The fuel cell system according to claim 1 or 2, wherein the first predetermined condition includes at least the ambient temperature being below a predetermined temperature.

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

5. The fuel cell system according to claim 4, wherein the first predetermined condition further includes that the elapsed time since the completion of filling the fuel tank with the fuel gas exceeds the first predetermined time.

6. The control device is configured to execute the pulse control mode when a second predetermined condition is met. The fuel cell system according to claim 1 or 2, wherein the second predetermined condition includes the state in which the current value of the fuel cell is equal to or greater than a second predetermined value continues for a second predetermined time or longer.

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