Fuel cell system

Abstract

To provide a fuel cell system with a simple configuration.SOLUTION: The fuel cell system includes: a fuel gas supply unit 20 that has a tank 21 capable of storing fuel gas in a releasable manner; an oxidant gas supply unit having an air pump for pumping oxidant gas; a fuel cell stack 40 for generating electricity through an electrochemical reaction of the fuel gas and the oxidant gas; a DC / DC converter 50 for converting a voltage of electric power generated in the fuel cell stack 40; a heat exchanger 62 having a circulation circuit 63 through which a refrigerant for cooling the fuel cell stack 40 circulates; and a control unit for controlling the power generation in the fuel cell stack 40 by controlling the supply of the fuel gas by the fuel gas supply unit 20 and the supply of the oxidant gas by the oxidant gas supply unit. The tank 21, the fuel cell stack 40, and the DC / DC converter 50 are provided in the middle of the circulation circuit 63.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A fuel cell system is disclosed in Patent Document 1. The fuel cell system includes a fuel cell, a fuel gas supply system, an oxidizing gas supply system, and a cooling system. The fuel gas supply system includes a hydrogen gas tank, which is a hydrogen storage unit that stores hydrogen gas at high pressure to supply hydrogen, which is a fuel gas, to the fuel cell, or a hydrogen storage unit that uses a hydrogen storage alloy.

[0003] The oxidizing gas supply system includes an oxidizing gas blower that supplies air containing oxygen, which is an oxidizing gas, to the fuel cell. The cooling system includes a heat exchanger and a coolant pump. The fuel cell and the heat exchanger are connected via a coolant pipe. A cooling pump that circulates the coolant is disposed in the coolant pipe. The fuel cell is cooled by the coolant.

[0004] A drive motor is also connected to the fuel cell via a power control unit. The power control unit includes a DC / DC converter that increases and decreases the voltage of the power generated by the fuel cell. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-157512 A Summary of the Invention [Problem to be solved by the invention]

[0006] As hydrogen gas is released from the hydrogen gas tank, the pressure and temperature inside the hydrogen gas tank decrease. Therefore, the hydrogen gas is less likely to be released due to the decrease in pressure of the hydrogen gas released from the hydrogen gas tank. Therefore, it is conceivable to provide a separate heating device to heat the hydrogen gas tank.

[0007] In addition, Joule heat is generated when current is applied to the DC / DC converter, which reduces the operability of the DC / DC converter. Therefore, it is considered to provide a separate cooling device to cool the DC / DC converter.

[0008] Implementing these measures would result in a problem of the fuel cell system becoming complicated in configuration. [Means for solving the problem]

[0009] A fuel cell system for solving the above problems includes a fuel gas supply unit having a tank for releasably storing fuel gas, an oxidant gas supply unit having an air pump for pressurizing oxidant gas, a fuel cell stack that generates electricity by an electrochemical reaction between the fuel gas and the oxidant gas, a DC / DC converter that converts the voltage of the electricity generated in the fuel cell stack, a heat exchange device having a circulation circuit through which a refrigerant that cools the fuel cell stack circulates, and a control device that controls power generation in the fuel cell stack by controlling the supply of the fuel gas by the fuel gas supply unit and the supply of the oxidant gas by the oxidant gas supply unit, and the tank, the fuel cell stack, and the DC / DC converter are provided in the middle of the circulation circuit.

[0010] According to the above configuration, the fuel cell stack and the DC / DC converter are cooled by heat exchange with the coolant circulating in the circulation circuit. At this time, the coolant is heated by heat exchange with the fuel cell stack and the DC / DC converter. When the coolant thus heated passes through a tank provided midway through the circulation circuit, the tank is heated by heat exchange with the tank. This prevents the temperature of the tank from decreasing due to the release of fuel gas, and therefore prevents a decrease in the pressure of the fuel gas released from the tank. In this way, a single heat exchange device can cool the fuel cell stack, cool the DC / DC converter, and heat the tank. This allows the configuration of the fuel cell system to be simplified. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a side view of a bicycle equipped with a fuel cell system according to an embodiment. [Diagram 2] FIG. 2 is a circuit diagram of the fuel cell system according to the embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing a circulation circuit of the fuel cell system according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, one embodiment will be described with reference to FIGS. As shown in FIG. 1, the fuel cell system is mounted on a bicycle body 10 to form an electrically assisted bicycle.

[0013] <Bicycle body 10> First, the structure of the bicycle body 10 will be briefly described. The bicycle body 10 includes a body frame 11, a handlebar 12, a saddle 13, a front wheel 14, a rear wheel 15, a drive unit 16, and a housing 18.

[0014] The body frame 11 has a front frame 11a that extends vertically when the bicycle body 10 is upright on a horizontal plane, a down frame 11b that extends rearward from the rear surface of the front frame 11a, and an upright frame 11c that extends upward from the rear end of the down frame 11b. The body frame 11 also has a lower frame 11e that extends rearward from the rear end of the down frame 11b, and an upper frame 11d that extends from the rear end of the lower frame 11e toward the upper part of the upright frame 11c.

[0015] A fork 19 is supported by the front frame 11a so as to be rotatable about the axis of the front frame 11a. A front wheel 14 is rotatably supported by the lower end of the fork 19. The upper end of the fork 19 protrudes from the upper end of the front frame 11a. A handlebar 12 is connected to the upper end of the fork 19.

[0016] A saddle 13 is connected to the upper end of the standing frame 11c. A holder 22 is connected to the standing frame 11c. A rear wheel 15 is rotatably supported at the rear end of the lower frame 11e.

[0017] The drive unit 16 is attached below the connection between the down frame 11b and the lower frame 11e. The drive unit 16 includes a pair of pedals 17 that rotate the rear wheel 15 via a well-known crank, sprocket, and chain (not shown), and a motor 66 that assists the pedals 17 in rotating the rear wheel 15.

[0018] The housing 18 is attached to a portion surrounded by the standing frame 11c, the upper frame 11d, and the lower frame 11e. The housing 18 accommodates an air pump 31, a fuel cell stack 40, a DC / DC converter 50, a battery 60, a water pump 64, an inverter 65, a control device 67, and a power supply 68 therein.

[0019] <Fuel cell system> Next, the fuel cell system will be described. As shown in FIG. 2, the fuel cell system includes a fuel gas supply unit 20, an oxidant gas supply unit 30, a fuel cell stack 40, a DC / DC converter 50, a switch 61, a heat exchanger 62, a controller 67, and a power supply 68.

[0020] (Fuel gas supply unit 20) 2 and 3, the fuel gas supply unit 20 supplies hydrogen as fuel gas to the fuel cell stack 40. The fuel gas supply unit 20 includes a canister 21 that releasably stores hydrogen, a holder 22 that houses the canister 21, a first solenoid valve 24, and a second solenoid valve 25.

[0021] As shown in FIG. 3, the holder 22 has a housing portion 23 for removably housing the canister 21. 2, the canister 21 is connected to the fuel cell stack 40 via a fuel gas supply pipe. The first solenoid valve 24 is provided midway through the fuel gas supply pipe. The first solenoid valve 24 is driven to open and close, thereby controlling the supply of hydrogen from the canister 21 to the fuel cell stack 40.

[0022] The second solenoid valve 25 is provided midway through a fuel gas discharge pipe that discharges hydrogen off-gas within the fuel cell stack 40. The manner in which hydrogen is discharged from the fuel cell stack 40 is controlled by driving the second solenoid valve 25 to open and close.

[0023] (Oxidizing gas supply unit 30) As shown in FIG. 2, the oxidizing gas supply unit 30 includes an air pump 31 that pumps air containing oxygen as an oxidizing gas to the fuel cell stack 40, a third solenoid valve 32, and a fourth solenoid valve 33.

[0024] The air pump 31 is connected to the fuel cell stack 40 via an oxidizing gas supply pipe. The third solenoid valve 32 is provided midway through the oxidizing gas supply pipe. The third solenoid valve 32 is driven to open and close, thereby controlling the supply of air from the air pump 31 to the fuel cell stack 40.

[0025] The fourth solenoid valve 33 is provided midway through an oxidant gas discharge pipe that discharges off-gas from the air inside the fuel cell stack 40. The manner in which air is discharged from the fuel cell stack 40 is controlled by driving the fourth solenoid valve 33 to open and close.

[0026] (Fuel Cell Stack 40) The fuel cell stack 40 generates electricity by utilizing an electrochemical reaction between hydrogen supplied from the fuel gas supply unit 20 and oxygen supplied from the oxidizing gas supply unit 30 .

[0027] As shown in FIG. 3, the fuel cell stack 40 includes a stack 42 formed by stacking multiple plate-shaped unit cells 41 each having a power generation portion, a pair of end plates 43, a pair of insulating plates 44, and a pair of terminal plates 45.

[0028] (DC / DC converter 50, switch 61) 2, the DC / DC converter 50 converts the voltage of the power generated in the fuel cell stack 40, and is electrically connected to the terminals of the fuel cell stack 40. The DC / DC converter 50 is electrically connected to a battery 60, an inverter 65, and a motor 66, in that order.

[0029] The switch 61 is configured to be switchable between an on state in which electrical connection is established between the fuel cell stack 40 and the DC / DC converter 50, and between the DC / DC converter 50 and the battery 60, and an off state in which no connection is established.

[0030] As shown in FIG. 3, the DC / DC converter 50 includes a substrate 52 and an element 51 fixed onto the substrate 52. 2, the battery 60 is a secondary battery that is charged with the power generated in the fuel cell stack 40 and supplies a direct current to the inverter 65. The battery 60 is, for example, a lithium ion secondary battery.

[0031] The inverter 65 converts the direct current supplied from the battery 60 into an alternating current. (Control device 67 and power supply 68) 2, the control device 67 controls the opening and closing of the first solenoid valve 24, the second solenoid valve 25, the third solenoid valve 32, and the fourth solenoid valve 33. In other words, the control device 67 controls the supply of hydrogen by the fuel gas supply unit 20 and the supply of air by the oxidizing gas supply unit 30, thereby controlling power generation in the fuel cell stack 40. The control device 67 controls the switch 61, the DC / DC converter 50, and the inverter 65.

[0032] The power supply 68 supplies power to the air pump 31, the water pump 64, the control device 67, and the like. (Heat exchange device 62) As shown in FIG. 3, the heat exchanger 62 has a circulation circuit 63 through which a coolant for cooling the fuel cell stack 40 circulates.

[0033] The circulation circuit 63 includes a first internal flow path 26, a second internal flow path 48, and a third internal flow path . The first internal flow passage 26 is provided inside the holder 22 .

[0034] The second internal flow path 48 is provided inside the fuel cell stack 40. More specifically, the second internal flow path 48 penetrates one end plate 43, the pair of insulating plates 44, the pair of terminal plates 45, and the stack 42. The one end plate 43 is provided with a refrigerant supply hole 46 serving as an inlet of the second internal flow path 48, and a refrigerant discharge hole 47 serving as an outlet.

[0035] The third internal flow path 54 is provided inside a water-cooled heat sink 55 that cools the DC / DC converter 50. A substrate 52 of the DC / DC converter 50 is fixed to the outer surface of the heat sink 55. A plurality of fins 53 are provided to protrude from the inner surface of the third internal flow path 54.

[0036] The circulation circuit 63 includes a first pipe 71 connecting the first internal flow path 26 and the second internal flow path 48, a second pipe 72 connecting the second internal flow path 48 and the third internal flow path 54, and a third pipe 73 connecting the third internal flow path 54 and the water pump 64. The circulation circuit 63 also includes a fourth pipe 74 connecting the water pump 64 and the first internal flow path 26.

[0037] That is, in the circulation circuit 63, a water pump 64, a canister 21, a fuel cell stack 40, and an element 51 are provided. The bicycle body 10 in this embodiment corresponds to the moving body according to the present invention, and the canister 21 in this embodiment corresponds to the tank described in the "Summary".

[0038] Next, the operation of this embodiment will be described. The fuel cell stack 40 and the DC / DC converter 50 are cooled by heat exchange with the refrigerant circulating through the circulation circuit 63. At this time, the refrigerant is heated by heat exchange with the fuel cell stack 40 and the DC / DC converter 50. When the refrigerant heated in this way passes through the canister 21 provided midway through the circulation circuit 63, the canister 21 is heated by heat exchange with the refrigerant. This prevents the temperature of the canister 21 from decreasing due to the release of hydrogen, and therefore prevents a decrease in the pressure of the hydrogen released from the canister 21.

[0039] Next, the effects of this embodiment will be described. (1) The canister 21, the fuel cell stack 40, and the DC / DC converter 50 are provided in the circulation circuit 63.

[0040] With such a configuration, the above-mentioned effects are achieved, and the single heat exchanger 62 can cool the fuel cell stack 40, cool the DC / DC converter 50, and heat the canister 21. This allows the configuration of the fuel cell system to be simplified.

[0041] (2) The fuel cell system includes a battery 60 that is charged with electricity generated in the fuel cell stack 40. A heater element 51 that generates heat when current is applied is provided in the middle of the circulation circuit 63. When the fuel cell system is started, a control device 67 supplies power from the battery 60 to the heater element 51 by turning on the switch 61.

[0042] For example, during a low-temperature start-up of the fuel cell system, the generated water remaining in the fuel cell stack 40 may freeze or the pressure of the hydrogen released from the canister 21 may decrease, which may result in a decrease in the power generation efficiency of the fuel cell stack 40.

[0043] In this regard, according to the above configuration, the element 51 generates heat when the fuel cell system is started, and the refrigerant is heated by heat exchange between the element 51 and the refrigerant. Then, when the heated refrigerant passes through the fuel cell stack 40 and the canister 21 through the circulation circuit 63, heat is exchanged between the fuel cell stack 40 and the canister 21, thereby heating the fuel cell stack 40 and the canister 21. Therefore, it is possible to suppress a decrease in power generation efficiency during low-temperature startup.

[0044] (3) The heater is element 51 of DC / DC converter 50. With this configuration, there is no need to provide a dedicated heater, and the configuration of the fuel cell system can be simplified.

[0045] <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.

[0046] Instead of using the element 51 of the DC / DC converter 50 as a heater, a dedicated heater may be provided. The heater may be omitted.

[0047] The moving object on which the fuel cell system is mounted is not limited to the bicycle body of an electrically assisted bicycle. The moving object may be, for example, an automobile. In addition, when the fuel cell system is mounted on an automobile, a tank fixed to the automobile may be used instead of the canister 21. [Explanation of symbols]

[0048] 10...Bicycle body (mobile body) 11...Vehicle frame 11a…Front frame 11b…Down frame 11c…standing frame 11d…Upper frame 11e…Lower frame 12…Handle 13…Saddle 14…Front wheel 15…Rear wheel 16...Drive unit 17…Pedal 18. Housing 19…Fork 20...Fuel gas supply section 21...Canister (tank) 22…Holder 23…Storage section 24…First solenoid valve 25...Second solenoid valve 26…First internal passage 30...Oxidant gas supply unit 31…Air pump 32...Third solenoid valve 33...4th solenoid valve 40…Fuel cell stack 41...Single cell 42...Laminate 43…End plate 44…Insulating plate 45…Terminal plate 46…Refrigerant supply hole 47...Refrigerant discharge hole 48…Second internal passage 50…DC / DC converter 51...Element (heater) 52... Circuit board 53…Finn 54…Third internal passage 55…Heat sink 60…Battery 61…Switch 62...Heat exchange device 63…Circulation circuit 64…Water pump 65…Inverter 66…Motor 67...Control device 68…Power supply 71…First pipe 72…Second piping 73…Third pipe 74…4th pipe

Claims

1. a fuel gas supply unit having a tank for releasably storing the fuel gas; an oxidant gas supply unit having an air pump that pumps the oxidant gas; a fuel cell stack that generates electricity by an electrochemical reaction between the fuel gas and the oxidant gas; a DC / DC converter that converts the voltage of the power generated in the fuel cell stack; a heat exchange device having a circulation circuit through which a coolant for cooling the fuel cell stack circulates; a control device that controls power generation in the fuel cell stack by controlling a supply of the fuel gas by the fuel gas supply unit and a supply of the oxidant gas by the oxidant gas supply unit, the tank, the fuel cell stack, and the DC / DC converter are provided in the circulation circuit; Fuel cell system.

2. a battery that charges the power generated in the fuel cell stack; A heater that generates heat when electricity is applied is provided in the circulation circuit, the control device supplies power from the battery to the heater when the fuel cell system is started. The fuel cell system according to claim 1 .

3. The heater is an element of the DC / DC converter. The fuel cell system according to claim 2 .

4. Installed on a moving vehicle, The fuel cell system according to any one of claims 1 to 3.

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