阅读说明：本技术 燃料电池系统 (Fuel cell system ) 是由 松末真明 于 2021-04-20 设计创作，主要内容包括：本发明提供能够通过在高温运转时减少循环气体流量来抑制燃料电池组内的干燥而使燃料电池组的发电性能提高的燃料电池系统。燃料电池系统具有燃料电池组、喷出器、向上述喷出器供给燃料气体的第1喷射器、向上述喷出器供给该燃料气体且上述燃料气体的喷射量小于上述第1喷射器的第2喷射器、向上述燃料电池组的各燃料极供给上述燃料气体的第3喷射器、燃料气体供给部、第1供给流路、能够使从上述第3喷射器向上述燃料电池组的各燃料极供给上述燃料气体的第2供给流路、循环流路、温度检测部、以及控制部。(The invention provides a fuel cell system capable of improving power generation performance of a fuel cell stack by reducing a circulation gas flow rate during high-temperature operation to suppress drying in the fuel cell stack. The fuel cell system includes a fuel cell stack, an ejector, a 1 st injector for supplying a fuel gas to the ejector, a 2 nd injector for supplying the fuel gas to the ejector and having an injection amount of the fuel gas smaller than that of the 1 st injector, a 3 rd injector for supplying the fuel gas to each fuel electrode of the fuel cell stack, a fuel gas supply unit, a 1 st supply flow path, a 2 nd supply flow path capable of supplying the fuel gas from the 3 rd injector to each fuel electrode of the fuel cell stack, a circulation flow path, a temperature detection unit, and a control unit.)

1. A fuel cell system characterized by comprising:

a fuel cell stack;

an ejector;

an injector assembly unit including a 1 st injector and a 2 nd injector, the 1 st injector supplying the injector with the fuel gas, the 2 nd injector being arranged in parallel with the 1 st injector, supplying the injector with the fuel gas, and an injection amount of the fuel gas being smaller than that of the 1 st injector;

a 3 rd injector that supplies the fuel gas to each fuel electrode of the fuel cell stack;

a fuel gas supply unit configured to supply the fuel gas to the 1 st injector, the 2 nd injector, and the 3 rd injector;

a 1 st supply flow path which connects the fuel gas supply unit, the injector assembly unit, the ejector, and the fuel cell stack in this order;

a 2 nd supply flow path which branches off in a region between the fuel gas supply unit and the injector assembly unit of the 1 st supply flow path, bypasses the injector assembly unit and the ejector, and merges with the 1 st supply flow path at a position downstream of the ejector so that the fuel gas can be supplied from the 3 rd injector to each fuel electrode of the fuel cell stack;

a circulation flow path that collects fuel off-gas discharged from each fuel electrode of the fuel cell stack and returns the fuel off-gas to the ejector as circulation gas;

a temperature detection unit that detects a temperature of the fuel cell stack; and

a control part for controlling the operation of the display device,

the ejector supplies a mixed gas containing the fuel gas and the circulation gas to each fuel electrode of the fuel cell stack,

when the temperature of the fuel cell stack detected by the temperature detection unit exceeds a predetermined threshold value, the control unit performs control such that the fuel gas is supplied to the ejector by switching from the 1 st injector to the 2 nd injector, and the fuel gas is supplied to each fuel electrode of the fuel cell stack from the 3 rd injector.

2. The fuel cell system according to claim 1,

when the temperature of the fuel cell stack detected by the temperature detection unit is equal to or lower than the predetermined threshold value, the control unit controls the ejector to be supplied with the fuel gas from the 1 st injector, and controls the ejector not to be supplied with the fuel gas from the 2 nd injector and not to be supplied with the fuel gas from the 3 rd injector.

Technical Field

The present disclosure relates to a fuel cell system.

Background

A Fuel Cell (FC) is a fuel cell stack (hereinafter, referred to simply as a stack) in which a plurality of single cells (hereinafter, referred to as cells) are stacked, and hydrogen (H) as a fuel gas passes through the fuel cell stack₂) With oxygen (O) as the oxidant gas₂) And a power generation device for taking out electric energy by the electrochemical reaction of (3). In addition, hereinafter, the fuel gas and the oxidizing gas may be simply referred to as "reaction gas" or "gas" without being particularly distinguished.

The unit cell of the fuel cell is generally composed of a Membrane Electrode Assembly (MEA) and two separators that sandwich both surfaces of the Membrane Electrode Assembly as needed.

The membrane electrode assembly has the following structure: in the presence of protons (H)⁺) A conductive solid polymer electrolyte membrane (hereinafter, also simply referred to as "electrolyte membrane") has a catalyst layer and a gas diffusion layer formed on each surface thereof in this order.

The separator generally has a structure in which a groove serving as a flow path for the reaction gas is formed on a surface in contact with the gas diffusion layer. The separator also functions as an electrical collector for power generation.

In a fuel electrode (anode) of the fuel cell, hydrogen supplied from a gas flow path and a gas diffusion layer is protonated by the catalytic action of a catalyst layer, passes through an electrolyte membrane, and moves to an oxidant electrode (cathode). The electrons generated at the same time do work through an external circuit and move toward the cathode. The oxygen supplied to the cathode reacts with the protons and electrons at the cathode to produce water.

The generated water imparts a moderate humidity to the electrolyte membrane, and excess water is discharged to the outside of the system through the gas diffusion layer.

In a fuel cell system in which a fuel off-gas containing excess fuel from a fuel electrode is circulated to a fuel supply side, it is desirable to ensure good fuel circulation in all operating regions from a low load to a high load.

For example, patent document 1 discloses a fuel cell system in which an opening degree adjustment mechanism is provided together with a ejector bypass passage, and these are controlled in accordance with an operation load state.

Patent document 2 discloses a fuel cell system including a bypass flow path and a buffer tank provided in the bypass flow path.

Patent document 1: japanese patent laid-open publication No. 2003-151593

Patent document 2: japanese patent laid-open No. 2007 & 242476

During high-temperature operation of the stack, water vapor contained in the anode off-gas (entrained water vapor from the stack) increases. On the other hand, it is also necessary to suppress drying in the battery pack during high-temperature operation. Therefore, it is necessary to suppress the flow rate of the anode off-gas discharged from the stack to the outside of the system during high-temperature operation. In addition, even in a fuel cell system including a circulation flow path through which the anode off-gas circulates, the water vapor discharged from the stack is condensed in the gas-liquid separator provided in the circulation flow path, the circulation flow path having a temperature lower than the temperature in the stack, and the like. Therefore, the total amount of water vapor contained in the anode off-gas is not returned to the stack as the circulation gas. Therefore, the inside of the battery pack tends to dry.

In the fuel cell system described in patent document 1, the fuel gas is introduced into the stack from the ejector bypass, whereby the circulation gas flow rate can be reduced by utilizing a backflow phenomenon to the ejector due to a high pressure loss at the stack inlet. This can reduce the amount of the carry-off steam from the battery pack. However, there are cases where it is difficult to reduce the amount of entrained steam from the stack in accordance with an increase in the temperature of the stack accompanying an increase in the load, regardless of the flow rate of the circulation gas supplied from the ejector to the stack.

In addition, in the fuel cell system described in patent document 2, the pressure increase on the outlet side of the ejector can be suppressed. However, when such a fuel cell system is used as a power source of a fuel cell vehicle (hereinafter, sometimes referred to as a vehicle), for example, responsiveness to electric power required according to an operating condition of the vehicle may be reduced.

Disclosure of Invention

The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide a fuel cell system capable of improving power generation performance of a fuel cell stack by reducing a flow rate of a circulation gas, that is, an amount of entrained steam from the fuel cell stack during high-temperature operation to suppress drying in the fuel cell stack.

In the present disclosure, there is provided a fuel cell system characterized by having:

a fuel cell stack;

an ejector;

an injector assembly unit including a 1 st injector and a 2 nd injector, the 1 st injector supplying a fuel gas to the ejector, the 2 nd injector being arranged in parallel with the 1 st injector, supplying the fuel gas to the ejector, and an injection amount of the fuel gas being smaller than that of the 1 st injector;

a 3 rd injector that supplies the fuel gas to each fuel electrode of the fuel cell stack;

a fuel gas supply unit configured to supply the fuel gas to the 1 st injector, the 2 nd injector, and the 3 rd injector;

a 1 st supply flow path which connects the fuel gas supply unit, the injector assembly unit, the ejector, and the fuel cell stack in this order;

a 2 nd supply flow path which branches off in a region between the fuel gas supply unit and the injector assembly unit of the 1 st supply flow path, bypasses the injector assembly unit and the ejector, and merges with the 1 st supply flow path at a position downstream of the ejector so that the fuel gas can be supplied from the 3 rd injector to each fuel electrode of the fuel cell stack;

a circulation flow path that collects fuel off-gas discharged from each fuel electrode of the fuel cell stack and returns the fuel off-gas to the ejector as circulation gas;

a temperature detection unit that detects a temperature of the fuel cell stack; and

a control part for controlling the operation of the display device,

the ejector supplies a mixed gas containing the fuel gas and the circulation gas to each fuel electrode of the fuel cell stack,

when the temperature of the fuel cell stack detected by the temperature detection unit exceeds a predetermined threshold value, the control unit performs control such that the fuel gas is supplied to the ejector by switching from the 1 st injector to the 2 nd injector, and the fuel gas is supplied to each fuel electrode of the fuel cell stack from the 3 rd injector.

The following may be configured: in the fuel cell system of the present disclosure, when the temperature of the fuel cell stack detected by the temperature detection unit is equal to or lower than the predetermined threshold value, the control unit controls the ejector to be supplied with the fuel gas from the 1 st injector, and to be supplied with no fuel gas from the 2 nd injector and no fuel gas from the 3 rd injector to each fuel electrode of the fuel cell stack.

According to the fuel cell system of the present disclosure, it is possible to provide a fuel cell system capable of improving the power generation performance of the fuel cell stack by reducing the circulation gas flow rate during high-temperature operation to suppress drying in the fuel cell stack.

Drawings

Fig. 1 is a schematic configuration diagram showing an example of the fuel cell system of the present disclosure.

Fig. 2 is a flowchart showing an example of the control method of the fuel cell system of the present disclosure.

Description of the reference numerals

11 … fuel cell stack; 12 … temperature detecting part; 13 … No. 1 supply flow path; 14 … circulation flow path; 15 … No. 2 supply flow path; 20 … ejector manifold; 21 … ejector No. 1; 22 … ejector No. 2; 23 … ejector No. 3; 24 … ejector; 30 … fuel gas supply section; 40 … oxidant gas supply unit; 41 … oxidant gas supply flow path; 42 … oxidant gas exhaust flow path; 50 … control section; 100 … fuel cell system.

Detailed Description

In the present disclosure, there is provided a fuel cell system characterized by having:

a fuel cell stack;

an ejector;

an injector assembly unit including a 1 st injector and a 2 nd injector, the 1 st injector supplying a fuel gas to the ejector, the 2 nd injector being arranged in parallel with the 1 st injector, supplying the fuel gas to the ejector, and an injection amount of the fuel gas being smaller than that of the 1 st injector;

a 3 rd injector that supplies the fuel gas to each fuel electrode of the fuel cell stack;

a fuel gas supply unit configured to supply the fuel gas to the 1 st injector, the 2 nd injector, and the 3 rd injector;

a 1 st supply flow path which connects the fuel gas supply unit, the injector assembly unit, the ejector, and the fuel cell stack in this order;

a 2 nd supply flow path which branches off in a region between the fuel gas supply unit and the injector assembly unit of the 1 st supply flow path, bypasses the injector assembly unit and the ejector, and merges with the 1 st supply flow path at a position downstream of the ejector so that the fuel gas can be supplied from the 3 rd injector to each fuel electrode of the fuel cell stack;

a circulation flow path that collects fuel off-gas discharged from each fuel electrode of the fuel cell stack and returns the fuel off-gas to the ejector as circulation gas;

a temperature detection unit that detects a temperature of the fuel cell stack; and

a control part for controlling the operation of the display device,

the ejector supplies a mixed gas containing the fuel gas and the circulation gas to each fuel electrode of the fuel cell stack,

when the temperature of the fuel cell stack detected by the temperature detection unit exceeds a predetermined threshold value, the control unit performs control such that the fuel gas is supplied to the ejector by switching from the 1 st injector to the 2 nd injector, and the fuel gas is supplied to each fuel electrode of the fuel cell stack from the 3 rd injector.

According to the present disclosure, in a fuel cell system including a circulation path having a plurality of injectors having different fuel gas injection amounts, the fuel gas is supplied to the cell stack from the 2 nd supply flow path (ejector bypass flow path) and the fuel gas is supplied to the ejector from the 2 nd injector having a small fuel gas injection amount during high-temperature operation, so that the circulation gas flow rate, that is, the amount of entrained water vapor from the cell stack can be reduced.

According to the present disclosure, during high-temperature operation, by using the ejector and the ejector bypass passage together, the fuel gas from the ejector bypass passage is forced to act against the circulation gas injection port side of the ejector, and therefore the circulation flow rate can be reduced.

In the high-temperature operation, if the flow rate of the fuel gas supplied to the ejector is reduced and the flow rate of the circulation gas is reduced without using the ejector bypass flow path, there is a possibility that the performance of the stack is degraded due to an increase in the anode overvoltage.

On the other hand, by using the ejector bypass flow path, the supply flow rate of the fuel gas to the stack can be increased, and the supply flow rate of the circulation gas to the stack can be decreased.

As the high-temperature operation, for example, an uphill running in which ensuring of the output is emphasized more than the fuel efficiency, a running while towing another vehicle, or the like is assumed in a vehicle equipped with the fuel cell system of the present disclosure.

Fig. 1 is a schematic configuration diagram showing an example of the fuel cell system of the present disclosure.

The fuel cell system 100 shown in fig. 1 includes a fuel cell stack 11, a temperature detection unit 12, a 1 st supply channel 13, a circulation channel 14, a 2 nd supply channel 15, an injector assembly 20 including a 1 st injector 21 and a 2 nd injector 22 in parallel, a 3 rd injector 23, an ejector 24, a fuel gas supply unit 30, an oxidizing gas supply unit 40, an oxidizing gas supply channel 41, an oxidizing gas discharge channel 42, and a control unit 50.

The temperature detector 12, the 1 st injector 21, the 2 nd injector 22, and the 3 rd injector 23 are electrically connected to the controller 50, respectively, the controller 50 obtains the temperature of the fuel cell stack 11 detected by the temperature detector 12, and the controller 50 controls the 1 st injector 21, the 2 nd injector 22, and the 3 rd injector 23 based on the temperature.

The fuel cell system of the present disclosure includes at least a fuel cell stack, a temperature detection unit, a 1 st supply flow path, a circulation flow path, a 2 nd supply flow path, an injector group unit including a 1 st injector and a 2 nd injector in parallel, a 3 rd injector, an injector, a fuel gas supply unit, and a control unit, and generally further includes an oxidizing gas supply unit, an oxidizing gas supply flow path, an oxidizing gas discharge flow path, a cooling water supply unit, a cooling water circulation flow path, and the like.

The fuel cell system of the present disclosure is generally mounted on a fuel cell vehicle having a drive source as an electric motor (motor).

The motor is not particularly limited, and may be a conventionally known motor.

The fuel cell stack may also supply electric power to the electric motor.

The fuel cell stack is configured by stacking a plurality of fuel cells.

The number of stacked single cells is not particularly limited, and may be, for example, 2 to several hundred, or 2 to 200.

The fuel cell stack may include end plates at both ends in the stacking direction of the unit cells.

The unit cell of the fuel cell includes at least a membrane electrode assembly including an oxidant electrode, an electrolyte membrane, and a fuel electrode, and may include two separators sandwiching both surfaces of the membrane electrode assembly as necessary.

The separator may have a reaction gas flow path on the surface in contact with the gas diffusion layer. The separator may have a cooling water flow path for maintaining the temperature of the fuel cell stack constant on the surface opposite to the surface in contact with the gas diffusion layer.

The separator may have a supply hole and a discharge hole for allowing the reaction gas and the cooling water to flow in the stacking direction of the unit cells.

Examples of the supply holes include a fuel gas supply hole, an oxidizing gas supply hole, and a cooling water supply hole.

Examples of the discharge holes include a fuel gas discharge hole, an oxidant gas discharge hole, and a cooling water discharge hole.

The separator may also be an air-impermeable conductive member or the like. The conductive member may be, for example, dense carbon obtained by compressing carbon to make it impermeable to air, or a metal plate obtained by press forming (for example, iron, aluminum, stainless steel, or the like). In addition, the separator may have a current collecting function.

The fuel cell stack may include manifolds such as an inlet manifold in which the supply holes communicate with each other, and an outlet manifold in which the discharge holes communicate with each other.

Examples of the inlet manifold include an anode inlet manifold, a cathode inlet manifold, and a coolant inlet manifold.

Examples of the outlet manifold include an anode outlet manifold, a cathode outlet manifold, and a cooling water outlet manifold.

The oxidant electrode includes an oxidant electrode catalyst layer and a gas diffusion layer.

The fuel electrode includes a fuel electrode catalyst layer and a gas diffusion layer.

The oxidant electrode catalyst layer and the fuel electrode catalyst layer may include, for example, a catalytic metal for promoting an electrochemical reaction, an electrolyte having proton conductivity, carbon particles having electron conductivity, and the like.

As the catalyst metal, platinum (Pt), an alloy of Pt and another metal (for example, a Pt alloy in which cobalt, nickel, or the like is mixed), or the like can be used.

The electrolyte may be a fluorine resin or the like. As the fluorine-based resin, for example, a perfluorosulfonic acid resin solution or the like may be used.

The catalytic metal may be supported on carbon particles, and in each catalyst layer, the carbon particles (catalyst particles) supporting the catalytic metal and the electrolyte may be present in a mixed state.

As the carbon particles for supporting the catalyst metal (carbon particles for supporting), for example, hydrophobized carbon particles obtained by heat-treating generally available carbon particles (carbon powder) to improve their own hydrophobicity can be used.

The gas diffusion layer may be a gas-permeable conductive member or the like.

Examples of the conductive member include a carbon porous body such as carbon cloth and carbon paper, and a metal porous body such as a metal mesh and a foamed metal.

The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include fluorine electrolyte membranes such as a perfluorosulfonic acid membrane containing water, and hydrocarbon electrolyte membranes. The electrolyte membrane may be a perfluorosulfonic acid membrane (manufactured by dupont) or the like.

The temperature detection unit detects the temperature of the fuel cell stack. The temperature of the fuel cell stack may be the temperature of cooling water circulating inside and outside the fuel cell stack. The temperature of the fuel cell stack may be the temperature of the cooling water flowing near the cooling water inlet of the fuel cell stack, or the temperature of the cooling water flowing near the cooling water outlet of the fuel cell stack.

The temperature detection unit is not particularly limited, and examples thereof include a temperature sensor.

The 1 st supply flow path connects the fuel gas supply unit, the injector assembly unit, the ejector, and the fuel cell stack in this order.

The 1 st supply flow path connects the fuel gas supply section and the injector assembly section so that the fuel gas can be supplied from the fuel gas supply section to the 1 st injector and the 2 nd injector in the injector assembly section. The 1 st supply flow path connects the injector assembly and the injector so that the fuel gas can be supplied from the injector assembly to the injector. The 1 st supply flow path connects the ejector and a fuel system gas inlet (an anode inlet manifold or the like) of the fuel cell stack, and allows the ejector to supply the mixed gas to each fuel electrode of the fuel cell stack. Further, the fuel system gas is a concept including a fuel gas and a mixed gas including the fuel gas and the circulation gas.

The 2 nd supply flow path branches off at a position downstream of the fuel gas supply unit of the 1 st supply flow path, that is, in a region between the fuel gas supply unit and the injector assembly unit of the 1 st supply flow path, and bypasses the injector assembly unit and the ejector to merge with the 1 st supply flow path at a position downstream of the ejector, so that the fuel gas can be supplied from the 3 rd injector to each fuel electrode of the fuel cell stack. Therefore, the 2 nd supply flow path connects the fuel gas supply section and the 3 rd injector so that the fuel gas can be supplied from the fuel gas supply section to the 3 rd injector.

The 2 nd supply flow path is a ejector bypass flow path that bypasses the ejector and can directly supply the fuel gas to the fuel cell stack.

The circulation flow path connects a fuel off-gas discharge port (anode outlet manifold, etc.) of the fuel cell stack to the ejector, and can recover the fuel off-gas discharged from each fuel electrode of the fuel cell stack and return the fuel off-gas to the ejector as a circulation gas.

The fuel off gas mainly includes fuel gas that passes through the fuel electrode without reacting, and moisture that reaches the fuel electrode from water produced at the oxidizer electrode.

The circulation flow path may be provided with a gas-liquid separator for removing dew condensation water generated by cooling of steam in the fuel off-gas in the circulation flow path. Further, a drain passage branched from the circulation passage by the gas-liquid separator may be provided, and a drain valve may be provided in the drain passage.

In the gas-liquid separator, the removed dew condensation water may be discharged by opening a drain valve provided in a drain passage branched from the circulation passage.

Further, a circulation pump for efficiently supplying the circulation gas to the ejector may be provided in the circulation flow path.

The ejector supplies a mixed gas including a fuel gas and a circulation gas to each fuel electrode of the fuel cell stack. As the ejector, a conventionally known ejector can be used.

The ejector assembly has a 1 st ejector and a 2 nd ejector in parallel.

The 1 st injector supplies fuel gas to the ejector.

The 2 nd injector is arranged in parallel with the 1 st injector, supplies the fuel gas to the ejector, and has an injection amount of the fuel gas smaller than that of the 1 st injector.

The injection amount of the fuel gas of the 2 nd injector is not particularly limited as long as it is smaller than that of the 1 st injector.

The following may be configured: each injector in the injector assembly is electrically connected to the control unit, and any one of the injectors in the injector assembly can be used individually by a signal from the control unit. In order to switch the injector used in the injector integrated portion, a switching valve of the injector may be disposed in the injector integrated portion. The following may be configured: the switching valve is electrically connected to the control unit, and switches the injector to be used by controlling the switching valve based on a signal from the control unit.

The 3 rd injector is disposed on the 2 nd supply flow path separately from the injector group portion, and directly supplies the fuel gas to each fuel electrode of the fuel cell stack.

The injection amount of the fuel gas of the 3 rd injector is not particularly limited, but may be smaller than that of the 1 st injector. The injection amount of the fuel gas from the 3 rd injector may be larger than the injection amount of the fuel gas from the 2 nd injector, may be smaller than the injection amount of the fuel gas from the 2 nd injector, or may be the same as the injection amount of the fuel gas from the 2 nd injector. From the viewpoint of reducing the circulation flow rate, the injection amount of the fuel gas of the 3 rd injector may be larger than that of the 2 nd injector.

In general, the 2 nd supply flow path merges with the 1 st supply flow path at a position downstream of the ejector of the 1 st supply flow path, and the pressure loss in the vicinity of the fuel system gas inlet (anode inlet manifold, etc.) of the stack is larger than that of the 1 st supply flow path, so that a part of the fuel gas supplied from the 3 rd injector to the fuel cell stack flows back in the 1 st supply flow path, thereby suppressing the supply of the mixed gas from the ejector to the fuel cell stack. This reduces the flow rate of the circulation gas, and reduces the amount of water vapor carried away by the anode off-gas discharged from the fuel cell stack.

In addition, by using the 2 nd injector, which has a smaller injection amount of the fuel gas than the 1 st injector, together with the 3 rd injector, it is possible to suppress an increase in the anode overvoltage, and to suppress a decrease in the performance of the stack.

The following may be configured: the 3 rd injector is electrically connected to the control unit, and the control unit can control the on/off of the start switch of the 3 rd injector.

The fuel gas supply unit supplies fuel gas to the 1 st injector, the 2 nd injector, and the 3 rd injector.

The fuel gas is a gas mainly containing hydrogen, and may be hydrogen gas, for example.

Examples of the fuel gas supply unit include a fuel tank, and specifically include a liquid hydrogen tank and a compressed hydrogen tank.

The following may be configured: the fuel gas supply unit is electrically connected to the control unit, and the fuel gas supply unit can control the injector that supplies the fuel gas in response to a signal from the control unit. Further, a control valve for controlling the supply of the fuel gas to the 3 rd injector may be disposed in the 2 nd supply flow path at a position upstream of the 3 rd injector. The following may be configured: the control valve is electrically connected to the control unit, and controls the opening and closing of the control valve by a signal from the control unit, thereby controlling the supply of the fuel gas from the fuel gas supply unit to the 3 rd injector.

The fuel cell system may further include an oxidizing gas supply unit, an oxidizing gas supply passage, and an oxidizing gas discharge passage.

The oxidizing gas supply unit supplies an oxidizing gas to at least each oxidizing electrode of the fuel cell stack.

As the oxidizing gas supply unit, for example, an air compressor or the like can be used. The air compressor is driven in accordance with a control signal from the control unit, and the oxidant gas is introduced into the cathode side (oxidant electrode, cathode inlet manifold, etc.) of the fuel cell.

The oxidizing gas supply passage connects the fuel cell stack and the oxidizing gas supply unit to supply the oxidizing gas from the oxidizing gas supply unit to each oxidizing electrode of the fuel cell stack.

The oxidant gas may be an oxygen-containing gas, or may be air, dry air, pure oxygen, or the like.

The oxidizing gas discharge flow path can discharge the oxidizing gas from each oxidizing electrode of the fuel cell stack.

The fuel cell system may further include a cooling water supply unit and a cooling water circulation flow path.

The cooling water circulation flow path is communicated with a cooling water inlet manifold and a cooling water outlet manifold provided in the fuel cell stack, and can cool the fuel cell stack by circulating the cooling water supplied from the cooling water supply unit inside and outside the fuel cell stack.

Examples of the cooling water supply unit include a cooling water pump.

As the cooling water (refrigerant), for example, a mixed solution of ethylene glycol and water can be used to prevent freezing at low temperatures.

The fuel cell system may further include a fuel off-gas discharge unit.

The fuel off-gas discharge unit may discharge the fuel off-gas having a concentration of the fuel gas equal to or lower than a predetermined concentration to the outside. Further, the outside refers to the outside of the fuel cell system.

The fuel off-gas discharge unit may be provided with a fuel off-gas discharge valve, and may be provided with a fuel off-gas discharge flow path as necessary.

The fuel off-gas discharge valve adjusts the discharge flow rate of the fuel off-gas.

The fuel off-gas discharge flow path may be branched from the circulation flow path.

For example, when the concentration of the fuel gas such as hydrogen in the fuel off-gas is equal to or less than a predetermined concentration, the fuel off-gas discharge unit may discharge the fuel off-gas to the outside. The predetermined concentration of the fuel gas is not particularly limited, and may be set as appropriate in consideration of, for example, fuel efficiency of the fuel cell system.

The method of detecting the concentration of the fuel gas in the fuel off-gas is not particularly limited, and, for example, a conventionally known concentration sensor or the like can be used.

The control unit controls the fuel cell system.

The control unit may be connected to the temperature detection unit, the injector group unit, the 3 rd injector, the fuel gas supply unit, the fuel off gas discharge unit, the oxidizing gas supply unit, and the like via the input/output interface.

The control unit performs determination as to whether or not the temperature of the fuel cell stack detected by the temperature detection unit exceeds a predetermined threshold value, switching of the injectors used in the injector group unit, on/off control of the activation switch of the 3 rd injector, and the like.

The control unit physically includes, for example, an arithmetic processing device such as a CPU (central processing unit), a storage device such as a ROM (read only memory) for storing control programs and control data to be processed by the CPU, a RAM (random access memory) mainly used as various work areas for control processing, and an input/output interface. The control unit may be a control device such as an ECU (engine control unit).

Fig. 2 is a flowchart showing an example of the control method of the fuel cell system of the present disclosure. In addition, the present disclosure is not necessarily limited to the present exemplary embodiment.

In the control method shown in fig. 2, first, the control unit supplies the fuel gas from the 1 st injector to the ejector at the start of operation or at the time of normal operation of the fuel cell stack, and supplies the mixed gas to each fuel electrode of the fuel cell stack using the ejector.

Then, the temperature detection unit detects the temperature of the fuel cell stack.

When the detected temperature of the fuel cell stack is equal to or lower than a predetermined threshold value, the control unit ends the control.

On the other hand, if the threshold value is exceeded, the control unit controls the ejector to supply the fuel gas from the 1 st injector to the 2 nd injector and to supply the mixed gas to each fuel electrode of the fuel cell stack using the ejector, and the control unit activates the 3 rd injector to supply the fuel gas from the 3 rd injector to each fuel electrode of the fuel cell stack and ends the control.

(1) Detection of temperature of fuel gas

The temperature detector detects the temperature of the fuel cell stack at predetermined intervals.

The method of detecting the temperature of the fuel cell stack is not particularly limited, and for example, the method may be configured such that: a conventionally known temperature sensor is provided in the fuel cell system, and the temperature of the fuel cell stack (for example, the temperature of the cooling water near the cooling water inlet (such as a cooling water inlet manifold) of the fuel cell stack) is detected using the temperature sensor.

The timing of detecting the temperature of the fuel cell stack is not particularly limited, and may be performed every predetermined time period after the start of the operation of the fuel cell stack, may be performed at the start of the operation of the fuel cell stack, may be constantly detected, and the detection timing may be appropriately set.

(2) Determination of whether or not the temperature of the fuel cell stack exceeds a predetermined threshold value

The control unit determines whether or not the temperature of the fuel cell stack detected by the temperature detection unit exceeds a predetermined threshold.

The threshold value of the temperature of the fuel cell stack can be set appropriately according to the performance of the fuel cell stack by preparing a data set indicating the correlation between the temperature of the fuel cell stack and the power generation performance of the fuel cell stack in advance by an experiment or the like, for example.

(3) Adjustment of the flow of circulating gas

(3-1) case where the temperature of the fuel cell stack exceeds a prescribed threshold value

When the temperature of the fuel cell stack detected by the temperature detection unit exceeds a predetermined threshold value, the control unit controls to supply the fuel gas to the ejector by switching from the 1 st injector to the 2 nd injector and to supply the mixed gas to each fuel electrode of the fuel cell stack by using the ejector, and the control unit activates the 3 rd injector to supply the fuel gas to each fuel electrode of the fuel cell stack from the 3 rd injector and ends the control.

This reduces the flow rate of the circulating gas during high-temperature operation of the fuel cell stack, thereby suppressing drying in the fuel cell stack and improving the power generation performance of the fuel cell stack.

(3-2) case where the temperature of the Fuel cell Stack is equal to or lower than a predetermined threshold

The control unit supplies the fuel gas from the 1 st injector to the ejector at the start of operation of the fuel cell stack, normal operation, and the like, and does not supply the fuel gas from the 2 nd injector to the ejector and does not supply the fuel gas from the 3 rd injector to each fuel electrode of the fuel cell stack.

Therefore, the control unit may end the control when the temperature of the fuel cell stack is equal to or lower than the predetermined threshold value and when the fuel gas is supplied from the 1 st injector to the ejector.

On the other hand, the following configuration may be adopted: when the temperature of the fuel cell stack is equal to or lower than a predetermined threshold value, and the fuel gas is supplied from the 2 nd injector to the ejector, and the fuel gas is supplied from the 3 rd injector to each fuel electrode of the fuel cell stack, the control unit controls to switch from the 2 nd injector to the 1 st injector to supply the fuel gas to the ejector, and stops the 3 rd injector to stop the supply of the fuel gas from the 3 rd injector to each fuel electrode of the fuel cell stack, and ends the control.

After the first control by the control unit is finished, the start timing of the second and subsequent controls is not particularly limited, and may be performed at predetermined time intervals or may be performed without leaving a time interval, and may be set as appropriate.