Fuel cell system

Abstract

To provide a fuel cell system capable of restraining termination of assist drive of a moving body by a motor.SOLUTION: A fuel cell system to be mounted on a mobile body that is configured to be movable by adding an assist driving force of a motor to a human-powered driving force by a crew includes a fuel cell for supplying the motor with electric power generated by an electrochemical reaction between fuel gas and oxidant gas, and a control device for controlling the supply amount of oxidant gas to the fuel cell. The fuel cell generates electricity in a state where a fuel gas discharge path through which the fuel gas is discharged is blocked. The control device executes remaining amount calculation processing for calculating the remaining amount of fuel gas in a fuel container, required amount calculation processing for calculating a required amount of fuel gas required for the fuel cell to continue generating electricity until the mobile body reaches a destination based on route information from a current location of the mobile body to the destination, and when the remaining amount is less than the required amount, restriction processing for reducing the supply amount of oxidant gas to the fuel cell as compared to when the remaining amount is more than the required amount.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fuel cell system. [Background technology]

[0002] Conventionally, an electrically assisted bicycle is configured to be movable by adding an assistive driving force from a motor to the driving force from the rider. Patent Document 1 discloses an electric bicycle in which the motor is driven by the power generated by a fuel cell. The electric bicycle is equipped with a hydrogen tank in which hydrogen gas is stored, and a fan that pressurizes the surrounding air to the fuel cell. In the electric bicycle, the motor output changes according to the rider's pedaling force, thereby changing the assist driving force. At this time, the amount of hydrogen gas and air supplied to the fuel cell changes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-119180 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electric bicycle described in Patent Document 1, there is a risk that the hydrogen gas will run out before the destination is reached, which may result in the fuel cell stopping power generation and causing the motor to stop assisting the vehicle. [Means for solving the problem]

[0005] A fuel cell system for solving the above problem is a fuel cell system mounted on a mobile body configured to be movable by adding assisted driving force from a motor to a manual driving force from an occupant, and includes a fuel cell that supplies electricity generated by an electrochemical reaction between fuel gas and oxidant gas to the motor, and a control device that controls the amount of oxidant gas supplied to the fuel cell, wherein the fuel cell generates electricity while a fuel gas exhaust path through which the fuel gas is discharged is blocked, and the control device executes a remaining amount calculation process that calculates the remaining amount of fuel gas in a fuel container, a required amount calculation process that calculates the required amount of fuel gas necessary for the fuel cell to continue generating electricity until the mobile body reaches the destination based on route information from the current location of the mobile body to the destination, and a restriction process that reduces the amount of oxidant gas supplied to the fuel cell when the remaining amount is less than the required amount, compared to when the remaining amount is greater than the required amount.

[0006] In a so-called dead-end type fuel cell, which generates power with the fuel gas exhaust passage blocked, the fuel gas is filled inside the fuel cell and power is generated without any new fuel gas being supplied, so the consumption of fuel gas increases as the supply of oxidant gas increases.

[0007] According to the above configuration, when the remaining amount of fuel gas is less than the required amount of fuel gas, the amount of oxidant gas supplied to the fuel cell is less than when the remaining amount of fuel gas is more than the required amount of fuel gas. This results in less fuel gas consumption than when the remaining amount of fuel gas is more than the required amount of fuel gas. This makes it possible to prevent the fuel cell from stopping power generation due to a shortage of fuel gas before the moving body reaches the destination. This makes it possible to prevent the motor-assisted driving of the moving body from ending. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a mobile object on which a fuel cell system according to an embodiment is mounted. [Diagram 2]FIG. 2 is a flowchart showing a procedure of the variable process executed by the control device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, one embodiment of a fuel cell system 10 will be described with reference to Figures 1 and 2. In this specification, "constant" does not only mean strictly constant, but also includes approximately constant within a range in which the effects of this embodiment are achieved.

[0010] 1, the fuel cell system 10 is mounted on a moving object M that is configured to move by adding an assist driving force from a motor 90 to a driving force driven by a human passenger. The moving object M is, for example, an electrically assisted bicycle.

[0011] The moving object M includes a fuel cell system 10, an inverter 80, and a motor 90. The inverter 80 converts DC power supplied from the fuel cell system 10 into AC power and outputs it to the motor 90. The motor 90 is, for example, a three-phase AC motor for driving the moving object M.

[0012] (Fuel Cell System 10) The fuel cell system 10 includes a fuel cell 20, a fuel gas supply / discharge system 30, an oxidant gas supply / discharge system 40, a DC / DC converter 50, a power storage device 60, and a control device .

[0013] (fuel cell 20) The fuel cell 20 is configured by stacking a plurality of unit cells (not shown) each having a membrane electrode assembly. The fuel cell 20 generates power by an electrochemical reaction between a fuel gas and an oxidizing gas. The fuel gas is, for example, hydrogen gas. The oxidizing gas is, for example, air.

[0014] (Fuel gas supply and exhaust system 30) The fuel gas supply / discharge system 30 includes a fuel container 31, a fuel gas supply passage 32, a first supply valve 33, a fuel gas discharge passage , and a first discharge valve .

[0015] Fuel gas is stored in the fuel container 31. The fuel container 31 is, for example, a canister that contains a hydrogen storage alloy that stores and releases hydrogen. The fuel container 31 is configured to be detachable from the moving body M.

[0016] The fuel gas supply path 32 connects the fuel container 31 and the fuel cell 20. The fuel gas in the fuel container 31 is supplied to the fuel cell 20 through the fuel gas supply path 32. The fuel gas supply path 32 is provided with a regulator (not shown) that adjusts the pressure of the fuel gas supplied to the fuel cell 20.

[0017] The first supply valve 33 is provided in the fuel gas supply passage 32. The first supply valve 33 is, for example, a solenoid valve. The supply of the fuel gas to the fuel cell 20 is controlled by driving the first supply valve 33 to open and close.

[0018] The fuel gas discharge path 34 is connected to the fuel cell 20. The fuel gas supplied to the fuel cell 20 is discharged to the outside of the fuel cell 20 through the fuel gas discharge path 34. The fuel gas discharge path 34 discharges the fuel gas into the atmosphere.

[0019] The first exhaust valve 35 is provided in the fuel gas exhaust passage 34. The first exhaust valve 35 is, for example, a solenoid valve. The manner in which the fuel gas is exhausted from the fuel cell 20 is controlled by driving the first exhaust valve 35 to open and close.

[0020] (Oxidant gas supply and exhaust system 40) The oxidizing gas supply / exhaust system 40 includes an air compressor 41 , an oxidizing gas supply passage 42 , a second supply valve 43 , an oxidizing gas exhaust passage 44 , and a second exhaust valve 45 .

[0021] The air compressor 41 compresses and sends air to the fuel cell 20. The air compressor 41 is driven by a drive motor (not shown). The oxidizing gas supply passage 42 connects the air compressor 41 and the fuel cell 20. The oxidizing gas delivered from the air compressor 41 is supplied to the fuel cell 20 through the oxidizing gas supply passage 42.

[0022] The second supply valve 43 is provided in the oxidant gas supply passage 42. The second supply valve 43 is, for example, a solenoid valve. The supply of the oxidant gas to the fuel cell 20 is controlled by the output of the drive motor of the air compressor 41 and the opening and closing drive of the second supply valve 43.

[0023] The oxidizing gas discharge channel 44 is connected to the fuel cell 20. The oxidizing gas supplied to the fuel cell 20 is discharged to the outside of the fuel cell 20 through the oxidizing gas discharge channel 44. The oxidizing gas discharge channel 44 discharges the oxidizing gas into the atmosphere.

[0024] The second exhaust valve 45 is provided in the oxidizing gas exhaust passage 44. The second exhaust valve 45 is, for example, a solenoid valve. The manner in which the oxidizing gas is exhausted from the fuel cell 20 is controlled by driving the second exhaust valve 45 to open and close.

[0025] The fuel cell 20 functions as a so-called dead-end type fuel cell that generates power with the fuel gas exhaust channel 34 closed and the oxidant gas exhaust channel 44 open. That is, the fuel cell 20 generates power with the first exhaust valve 35 closed and the second exhaust valve 45 open. The fuel cell 20 can also generate power with both the first exhaust valve 35 and the second exhaust valve 45 open.

[0026] Hereinafter, the operation of the fuel cell 20 in a state in which the first exhaust valve 35 is closed and the second exhaust valve 45 is open will be referred to as dead-end operation. In the dead-end operation, the fuel cell 20 is filled with fuel gas and oxidant gas is supplied to the inside of the fuel cell 20. At this time, new fuel gas is not supplied to the fuel cell 20 and the fuel gas is not discharged to the outside of the fuel cell 20. As a result, inside the fuel cell 20, an amount of fuel gas corresponding to the amount of oxidant gas supplied is consumed by an electrochemical reaction.

[0027] In the dead-end operation, the first exhaust valve 35 is driven to open and close at a predetermined cycle, whereby water produced by the electrochemical reaction in the fuel cell 20 is exhausted to the outside together with the fuel gas.

[0028] (DC / DC converter 50) The DC / DC converter 50 is electrically connected to the fuel cell 20. The DC / DC converter 50 transforms and outputs the DC power generated by the fuel cell 20. The DC / DC converter 50 is electrically connected to a power storage device 60 and an inverter 80.

[0029] (Electricity storage device 60) The power storage device 60 is connected in parallel to the inverter 80. The power storage device 60 is, for example, a secondary battery such as a lithium ion battery.

[0030] The power storage device 60 is charged with surplus power from the fuel cell 20 when the power generated by the fuel cell 20 is greater than the power required by the motor 90. This increases the amount of charge in the power storage device 60. The power storage device 60 is also charged with regenerative power from the motor 90. On the other hand, the power storage device 60 supplies power to the motor 90 when the power generated by the fuel cell 20 is less than the power required by the motor 90. This reduces the amount of charge in the power storage device 60.

[0031] (Control device 70) The control device 70 includes, for example, a CPU 71 and a memory 72. The CPU 71 executes various processes in the fuel cell system 10 in accordance with the programs stored in the memory 72.

[0032] The control device 70 controls the operation of the DC / DC converter 50 so that the power generated by the fuel cell 20 corresponds to the power required by the motor 90. During dead-end operation, the control device 70 controls the output of the DC / DC converter 50 so that a constant power is supplied to the motor 90.

[0033] The control device 70 controls the operation of the inverter 80, thereby controlling the rotation speed of the motor 90. Note that the inverter 80 may be controlled by a control device other than the control device 70.

[0034] When fuel gas is supplied to the fuel cell 20 during dead-end operation, the control device 70 opens the first supply valve 33 and closes the first exhaust valve 35. The fuel gas is supplied to the fuel cell 20 with its pressure adjusted by a regulator (not shown), and fills the inside of the fuel cell 20.

[0035] When supplying oxidant gas to the fuel cell 20, the control device 70 opens the second supply valve 43 and the second exhaust valve 45, and operates the air compressor 41. The control device 70 controls the output of the drive motor of the air compressor 41, thereby controlling the amount of oxidant gas supplied.

[0036] The control device 70 determines the amount of power generated by the fuel cell 20 based on the power required by the motor 90. During dead-end operation, the control device 70 keeps the amount of power generated by the fuel cell 20 constant, regardless of the power required by the motor 90. The control device 70 controls the output of the drive motor of the air compressor 41 based on the amount of power generated by the fuel cell 20, thereby controlling the supply amount of oxidant gas.

[0037] During the dead-end operation, the control device 70 limits the amount of oxidant gas supplied to the fuel cell 20 per unit time to a constant amount. This causes the amount of fuel gas consumed per unit time during power generation by the fuel cell 20 to be constant.

[0038] The control device 70 calculates the remaining amount of fuel gas in the fuel container 31 (hereinafter simply referred to as the remaining amount of fuel gas). The remaining amount of fuel gas is the amount of fuel gas that can be supplied from the fuel container 31 to the fuel cell 20. The control device 70 calculates the remaining amount of fuel gas based on at least one parameter, such as the pressure, temperature, weight, etc. of the fuel gas in the fuel container 31 acquired from a sensor (not shown). The control device 70 calculates the remaining amount of fuel gas based on a map that specifies the relationship between the at least one parameter and the remaining amount of fuel gas. This map is stored in advance in the memory 72, for example.

[0039] Based on route information from the current location of the moving body M to the destination (hereinafter simply referred to as route information), the control device 70 calculates the required amount of fuel gas (hereinafter simply referred to as the required amount of fuel gas) necessary for the fuel cell 20 to continue generating power until the moving body M reaches the destination.

[0040] The control device 70 acquires route information from a navigation device 100 that provides route guidance to the destination. The route information includes information such as the distance, undulations, and temperature on the route from the current location to the destination. The navigation device 100 acquires current location information from a satellite positioning system. The navigation device 100 is, for example, a terminal device such as a smartphone or a tablet terminal that is configured to be able to wirelessly communicate with a communication device provided in the control device 70. In the navigation device 100, the destination is set by an operation by the occupant.

[0041] In calculating the required amount of fuel gas, the control device 70 first calculates the arrival time required for the moving body M to reach the destination based on the distance on the route from the current location to the destination and the average moving speed of the moving body M. Then, the control device 70 calculates the consumption amount of fuel gas consumed until the arrival time has elapsed as the required amount of fuel gas, on the premise that the supply amount of oxidant gas per unit time is constant. More specifically, the control device 70 calculates the required amount of fuel gas based on the consumption amount of fuel gas per unit time during the above-mentioned dead-end operation and the arrival time. Since the consumption amount of fuel gas per unit time of the fuel cell 20 during the dead-end operation is constant, the control device 70 can calculate the required amount of fuel gas based on the arrival time.

[0042] (variable control) When a destination is set in the navigation device 100 by the occupant, the control device 70 executes variable control to vary the power generated by the fuel cell 20 according to the remaining amount of fuel gas. The control device 70 repeatedly executes the variable control at predetermined control intervals. The control device 70 repeatedly executes the variable control while the moving body M is moving toward the destination.

[0043] 2, after executing variable control, the control device 70 executes the process of step S1. In step S1, route information to the destination is obtained from the navigation device 100. After that, the process of the control device 70 proceeds to step S2.

[0044] In step S2, the control device 70 executes a remaining amount calculation process. The remaining amount calculation process is a process for calculating the remaining amount of fuel gas in the fuel container 31. After that, the process of the control device 70 proceeds to step S3.

[0045] In step S3, the control device 70 executes a required amount calculation process. The required amount calculation process is a process for calculating, based on the route information, the required amount of fuel gas required for the fuel cell 20 to continue generating power until the moving object M reaches the destination. After that, the process of the control device 70 proceeds to step S4.

[0046] In step S4, the control device 70 determines whether the remaining amount of fuel gas is equal to or greater than the required amount of fuel gas. If the remaining amount of fuel gas is equal to or greater than the required amount (step S4: YES), the process of the control device 70 proceeds to step S5. If the remaining amount of fuel gas is less than the required amount (step S4: NO), the process of the control device 70 proceeds to step S6.

[0047] In step S5, the control device 70 executes a supply process. The supply process is a process in which the amount of oxidant gas supplied to the fuel cell 20 per unit time is kept constant. In the supply process, a constant amount of oxidant gas is supplied to the fuel cell 20 performing dead-end operation, so that the amount of fuel gas consumed is a constant amount according to the amount of oxidant gas supplied. In the supply process, the power generated by the fuel cell 20 is kept constant. During the supply process, the power storage device 60 is charged by surplus power from the fuel cell 20, or supplies power to the motor 90 together with the fuel cell 20. Thereafter, the control device 70 ends the series of variable controls.

[0048] In step S6, the control device 70 executes a limiting process. The limiting process is a process in which the supply amount of oxidant gas per unit time to the fuel cell 20 is set to a constant amount less than the supply amount in the supplying process. In the limiting process, a constant amount of oxidant gas is supplied to the fuel cell 20 performing dead-end operation, so that the consumption amount of fuel gas is a constant amount according to the supply amount of oxidant gas. The consumption amount of fuel gas in the limiting process is less than the consumption amount of fuel gas in the supplying process. In the limiting process, the power generated by the fuel cell 20 is a constant amount less than the power generated in the supplying process. During the execution of the limiting process, the power storage device 60 is charged by the surplus power of the fuel cell 20, or supplies power to the motor 90 together with the fuel cell 20. After that, the control device 70 ends the series of variable controls.

[0049] During the execution of the limiting process, the generated power of the fuel cell 20 is smaller than during the supplying process, and therefore the assisting driving force by the motor 90 is smaller. Since the moving body M can move by manual driving force, it does not become unable to move even if the assisting driving force is reduced.

[0050] The operation of this embodiment will be described. In the fuel cell 20 performing the dead-end operation, power generation is performed in a state where no new fuel gas is supplied and the fuel gas is filled inside the fuel cell 20. Therefore, the consumption of fuel gas increases as the supply amount of oxidant gas increases.

[0051] According to this embodiment, when the remaining amount of fuel gas is less than the required amount of fuel gas, the amount of oxidant gas supplied to the fuel cell 20 is less than when the remaining amount of fuel gas is more than the required amount of fuel gas. This results in less consumption of fuel gas than when the remaining amount of fuel gas is more than the required amount of fuel gas.

[0052] The effects of this embodiment will be described. (1) The control device 70 executes a remaining amount calculation process, a required amount calculation process, and a limiting process. In the limiting process, when the remaining amount of fuel gas is less than the required amount of fuel gas, the amount of oxidant gas supplied to the fuel cell 20 is reduced compared to when the remaining amount of fuel gas is more than the required amount of fuel gas.

[0053] According to the above configuration, it is possible to prevent the fuel gas from running short and the power generation of the fuel cell 20 from stopping before the moving object M reaches the destination. Therefore, it is possible to prevent the assist drive of the moving object M by the motor 90 from ending.

[0054] (2) The limiting process is a process for limiting the amount of oxidant gas supplied to the fuel cell 20 per unit time to a constant amount. According to the above configuration, the amount of oxidant gas supplied to the fuel cell 20 per unit time is constant during the execution of the restriction process, so that a sudden increase in the amount of fuel gas consumed can be suppressed. Therefore, it is possible to suppress a shortage of fuel gas before the moving body M reaches the destination.

[0055] (3) When the remaining amount of fuel gas is greater than the required amount of fuel gas, the control device 70 executes a supply process to set the amount of oxidant gas supplied per unit time to the fuel cell 20 at a constant amount. The limiting process is a process to set the amount of oxidant gas supplied per unit time to the fuel cell 20 at a constant amount that is less than the amount supplied in the supply process.

[0056] According to the above configuration, the supply amount of the oxidant gas is constant during the supply process, so that a sudden increase in the consumption amount of the fuel gas can be suppressed. This makes it difficult for the process of the control device 70 to shift from the supply process to the restriction process. Therefore, it is possible to further suppress a shortage of the fuel gas before the moving body M reaches the destination.

[0057] (4) When the restriction process is being executed, the power storage device 60 is charged with surplus power from the fuel cell 20 if the power generated by the fuel cell 20 is greater than the power required for the motor 90, and supplies power to the motor 90 if the power generated by the fuel cell 20 is less than the power required.

[0058] According to the above configuration, even if the remaining amount of fuel gas is less than the required amount of fuel gas, electric power is supplied from the power storage device 60 to the motor 90, so that a shortage of assist drive force by the motor 90 can be suppressed.

[0059] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0060] The fuel container 31 does not have to have a hydrogen storage alloy built in, and may be, for example, a high-pressure tank capable of storing high-pressure gas. The power storage device 60 may be a secondary battery such as a lead storage battery, a nickel-cadmium battery, or a nickel-metal hydride battery, or may be a capacitor.

[0061] The control device 70 may calculate the remaining amount of fuel gas using an arithmetic expression that expresses the relationship between at least one parameter, such as the pressure, temperature, or weight, of the fuel gas in the fuel container 31 and the remaining amount of fuel gas.

[0062] When the amount of fuel gas stored in the fuel container 31 is fixed, the control device 70 may calculate the remaining amount of fuel gas based on the difference between the stored amount and the consumed amount of fuel gas. In this case, the control device 70 may calculate the consumed amount of fuel gas based on at least one parameter such as the amount of power generated by the fuel cell 20 or the flow rate of the fuel gas in the fuel gas supply path 32.

[0063] The navigation device 100 may be mounted on a moving object M. The moving object M is not limited to an electrically assisted bicycle, as long as it is configured to be movable by adding an assisted driving force to a human driving force. The moving object M may be, for example, an electrically assisted wheelchair.

[0064] When variable control is not being performed, that is, when a destination is not set by the occupant, the control device 70 may execute a control similar to the supply process. The power storage device 60 may operate only while either the supply process or the limit process is being executed.

[0065] The fuel cell system 10 does not necessarily have to include the power storage device 60. The control device 70 may change the amount of oxidant gas supplied per unit time to the fuel cell 20 in response to changes in the power demand of the motor 90 while at least one of the supply process and the limit process is being performed.

[0066] The control device 70 may execute a supply process when the remaining amount of fuel gas is greater than the required amount of fuel gas, and may execute a restriction process when the remaining amount of fuel gas is equal to or less than the required amount of fuel gas. [Explanation of symbols]

[0067] M...Moving object 10. Fuel cell system 20…fuel cell 30...Fuel gas supply and exhaust system 31...Fuel container 32...Fuel gas supply line 33…First supply valve 34...Fuel gas exhaust passage 35…First exhaust valve 40...Oxidant gas supply and exhaust system 41…Air compressor 42...Oxidant gas supply line 43…Second supply valve 44...Oxidant gas exhaust passage 45…Second exhaust valve 50…DC / DC converter 60...Electricity storage device 70...Control device 71…CPU 72…Memory 80…Inverter 90…Motor 100...Navigation equipment

Claims

1. A fuel cell system mounted on a moving body configured to be movable by adding an assist driving force by a motor to a driving force by a human driver, a fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas and supplies the electric power to the motor; a control device that controls a supply amount of the oxidant gas to the fuel cell, the fuel cell generates power in a state where a fuel gas discharge passage through which the fuel gas is discharged is blocked, The control device includes: a remaining amount calculation process for calculating a remaining amount of the fuel gas in the fuel container; a required amount calculation process for calculating a required amount of the fuel gas required for the fuel cell to continue generating power until the moving body reaches the destination based on route information from the current location of the moving body to the destination; when the remaining amount is smaller than the required amount, a limiting process is executed to reduce the amount of the oxidant gas supplied to the fuel cell compared to when the remaining amount is larger than the required amount. Fuel cell system.

2. the limiting process is a process for limiting the amount of the oxidant gas supplied to the fuel cell per unit time to a constant amount. The fuel cell system according to claim 1 .

3. when the remaining amount is greater than the required amount, the control device executes a supply process to set the amount of the oxidant gas supplied to the fuel cell per unit time to a constant amount; the limiting process is a process for setting the amount of the oxidant gas supplied to the fuel cell per unit time to a constant amount that is less than the amount supplied in the supply process; The fuel cell system according to claim 2 .

4. a power storage device which is charged with surplus power of the fuel cell when the power generated by the fuel cell is greater than the power required for the motor during execution of the limiting process, and which supplies power to the motor when the power generated by the fuel cell is less than the power required. The fuel cell system according to any one of claims 1 to 3.

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