Fuel cell system

Abstract

To provide a fuel cell system that can be designed to be compact in height.SOLUTION: A fuel cell system to be mounted on a vehicle includes a fuel cell, a water storage to store liquid water that is contained in an anode off-gas discharged from the fuel cell, cathode off-gas piping to flow a cathode off-gas discharged from the fuel cell, and drain piping connecting the water storage and the cathode off-gas piping. The drain piping is connected to the downstream of the cathode off-gas piping. The drain piping is tilted at an angle with respect to the horizontal direction greater than the maximum slope angle of the vehicle which is acceptable at sub-zero temperatures.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system.

Background Art

[0002] Various technologies have been proposed regarding fuel cells (FCs) as disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, a fuel cell system is disclosed that includes a gas-liquid separator that separates and stores liquid water from off-gas discharged from a fuel cell, an attitude control device that controls the attitude of the gas-liquid separator with respect to a vehicle, an instruction device that instructs the attitude control device of a control target for the attitude of the gas-liquid separator, and a detection sensor that detects the inclination of the vehicle, and determines a control target for the attitude of the gas-liquid separator according to the inclination of the vehicle. The drain pipe connected to the water storage section is often extended in the vertical direction from the viewpoint of drainage, but this increases the size of the fuel cell system in the height direction.

[0005] The present disclosure has been made in view of the above circumstances, and the main object is to provide a fuel cell system capable of reducing the size in the height direction.

Means for Solving the Problems

[0006] That is, the present disclosure includes the following aspects. <1> A fuel cell system for a vehicle, wherein the fuel cell system includes a fuel cell, and A water storage section for storing liquid water contained in the anode off-gas discharged from the fuel cell, A cathode off-gas pipe through which the cathode off-gas discharged from the fuel cell flows, And a drain pipe connecting the water storage section and the cathode off-gas pipe, The drain pipe is connected below the cathode off-gas pipe, The drain pipe is inclined at an angle equal to or greater than the maximum allowable inclination angle of the vehicle at sub-zero temperatures with respect to the horizontal direction. A fuel cell system.

Advantages of the Invention

[0007] The fuel cell system of the present disclosure can reduce the size in the height direction.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments according to the present disclosure will be described. Note that matters other than those specifically mentioned in this specification and necessary for the implementation of the present disclosure (for example, general configurations and manufacturing processes of fuel cell systems that do not characterize the present disclosure) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The present disclosure can be implemented based on the content disclosed in this specification and common general knowledge in the relevant field. Also, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships. In the present disclosure, the reaction gas supplied to the anode of the fuel cell is a fuel gas (anode gas), and the reaction gas supplied to the cathode of the fuel cell is an oxidant gas (cathode gas). The fuel gas is a gas mainly containing hydrogen and may be hydrogen. The oxidant gas is a gas containing oxygen and may be oxygen, air (air), or the like.

[0010] In the present disclosure, a fuel cell system for a vehicle, The fuel cell system includes a fuel cell, a water storage unit that stores the liquid water contained in the anode off-gas discharged from the fuel cell, a cathode off-gas pipe through which the cathode off-gas discharged from the fuel cell flows, and a drain pipe that connects the water storage unit and the cathode off-gas pipe, The drain pipe is connected below the cathode off-gas pipe, The drain pipe is inclined at an angle equal to or greater than the maximum inclination angle of the vehicle that can be tolerated at sub-zero temperatures with respect to the horizontal direction, providing a fuel cell system.

[0011] When the fuel cell system is stopped at sub-zero temperatures, if liquid water accumulates in the pipe downstream of the drain valve of the anode off-gas, there is a possibility of freezing and blockage. Therefore, the pipe downstream of the drain valve needs to be connected to the cathode off-gas pipe at an angle where liquid water does not stagnate. However, since it is necessary to mount the drain valve of the anode off-gas at the lower end of the fuel cell system so that liquid water does not flow back into the fuel cell, the cathode off-gas pipe through which the liquid water is drained also needs to be mounted at a lower position, and a large space in the height direction of the fuel cell system is required. According to the present disclosure, by connecting the drain pipe below the cathode off-gas pipe and tilting the drain pipe with respect to the horizontal direction, the mounting position of the cathode off-gas pipe, which can be the lowermost end of the fuel cell system, can be raised, the size of the fuel cell system in the height direction can be reduced, and it becomes easier to mount on various commercial products. Further, by setting the angle of inclination of the drain pipe to be equal to or greater than the maximum inclination angle of the vehicle that can be tolerated at sub-zero temperatures, the drainage performance when the fuel cell system is stopped at sub-zero temperatures is ensured, the retention of liquid water is prevented, and freezing blockage is suppressed. This prevents hydrogen deficiency due to the inability to exhaust the anode off-gas and prevents the fuel cell system from stopping.

[0012] FIG. 1 is a system configuration diagram showing an example of the fuel cell system of the present disclosure. The fuel cell system includes a fuel cell 10, a fuel gas system 20, and an oxidant gas system 30. In FIG. 1, the cooling system is omitted for convenience. The fuel gas system 20 includes a drain pipe 21, a drain valve 22, and a water storage part (not shown). The oxidant gas system 30 includes a cathode off-gas pipe 31. The drain pipe 21 is connected to the cathode off-gas pipe 31.

[0013] FIG. 2 is a cross-sectional schematic diagram showing an example of a part of the fuel cell system of the present disclosure. The drain pipe 21 connects the water storage part 23 and the cathode off-gas pipe 31. A drain valve 22 is provided in the drain pipe 21. The drain pipe 21 is connected below the cathode off-gas pipe 31 in a cross-sectional view of the cathode off-gas pipe. The drain pipe 21 is connected so as to be tangent to the cathode off-gas pipe 31. The drain pipe 21 is inclined at the maximum inclination angle of the vehicle that can be tolerated at sub-zero temperatures with respect to the horizontal direction.

[0014] FIG. 3 is a cross-sectional schematic diagram showing an example of a part of a conventional fuel cell system. In FIG. 3, a drain pipe 21 downstream of a drain valve 22 is connected to a cathode off-gas pipe 31 mounted directly below the drain pipe 21. In a conventional fuel cell system, a large space in the height direction is required. In a conventional fuel cell system, when the fuel cell system is stopped at sub-zero temperatures, liquid water may accumulate in the drain pipe 21 and freeze, causing blockage.

[0015] The fuel cell system of the present disclosure may be mounted on a moving body such as a vehicle and used, or may be mounted on a stationary power generation system such as a generator that supplies power to the outside of the fuel cell system and used. The vehicle may be a fuel cell vehicle or the like. Examples of moving bodies other than vehicles include railways, ships, airplanes, and the like. Further, the fuel cell system of the present disclosure may be mounted on a moving body such as a vehicle that can also run on the power of a secondary battery and used. The moving body and the stationary power generation system may be provided with the fuel cell system of the present disclosure. The moving body may have a drive unit such as a motor, an inverter, and a hybrid control system. The hybrid control system may be capable of driving the moving body by using the output of the fuel cell and the power of the secondary battery in combination.

[0016] The fuel cell system includes a fuel cell that generates power by the reaction of hydrogen and oxygen, a fuel gas system, and an oxidant gas system. The fuel cell system may include a control device, a cooling system, and the like.

[0017] The fuel cell may be a fuel cell stack in which a plurality of single cells (cells) of the fuel cell are stacked. In the present disclosure, both the cell and the fuel cell stack may be referred to as a fuel cell in some cases. The number of cells stacked in the fuel cell stack is not particularly limited, and may be, for example, 2 to several hundred. The fuel cell stack may have a current collector plate, a pressure plate, etc. at the ends in the stacking direction.

[0018] The cell may have a power generation part. The shape of the power generation part may be rectangular in plan view. The power generation part may be a membrane electrode assembly (MEA) including an electrolyte membrane and two electrodes. The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include fluorine-based electrolyte membranes such as thin films of perfluorosulfonic acid containing moisture, and hydrocarbon-based electrolyte membranes. As the electrolyte membrane, for example, a Nafion membrane (manufactured by DuPont) may be used. One of the two electrodes is an anode (fuel electrode), and the other is a cathode (oxidant electrode). The electrode includes a catalyst layer and may optionally include a gas diffusion layer. The power generation part may be a membrane electrode gas diffusion layer assembly (MEGA). The catalyst layer contains a catalyst, and the catalyst may include a catalyst metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, and a carrier having electron conductivity. As the catalyst metal, for example, platinum (Pt) and alloys composed of Pt and other metals (for example, Pt alloys mixed with cobalt, nickel, etc.) can be used. The catalyst metal used as the cathode catalyst and the catalyst metal used as the anode catalyst may be the same or different. As the electrolyte, a fluorine-based resin or the like may be used. As the fluorine-based resin, for example, a Nafion solution or the like may be used. The above catalyst metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalyst metal (catalyst-supported carrier) and the electrolyte may be mixed. Examples of the carrier for supporting the catalyst metal include carbon materials such as generally commercially available carbon. The gas diffusion layer may be a conductive member having pores. Examples of the conductive member include carbon porous bodies such as carbon cloth and carbon paper, and metal porous members such as metal mesh and foamed metal. The cell may include a separator. The separator collects the current generated by power generation and functions as a partition. In a cell, the separators are usually arranged on both sides in the stacking direction of the power generation part so that a pair of separators sandwich the power generation part. One of the pair of separators is an anode separator and the other is a cathode separator. The anode separator may have grooves serving as fuel gas flow paths on the surface on the power generation part side. The cathode separator may have grooves serving as oxidant gas flow paths on the surface on the power generation part side. The separator may have holes constituting a manifold such as supply holes and discharge holes for allowing a fluid to flow in the stacking direction of the cell. Examples of the separator may include dense carbon obtained by compressing carbon to make it gas-impermeable, and press-molded metals (such as iron, titanium, and stainless steel, etc.). The cell may be provided with an insulating resin frame disposed outside (outer periphery) in the plane direction of the membrane electrode assembly between the anode separator and the cathode separator. The resin frame is molded using a thermoplastic resin to be plate-shaped and frame-shaped, and seals between the anode separator and the cathode separator while holding the membrane electrode assembly in its central region. As the resin frame, for example, resins such as PE, PP, PET, and PEN can be used. The resin frame may be a three-layer sheet composed of three layers with an adhesive layer disposed on the surface layer.

[0019] The fuel gas system supplies fuel gas to the fuel cell and adjusts the flow rate of the fuel gas. The fuel gas system includes a water storage part and a drain pipe. The fuel gas system may include a fuel gas tank, a fuel gas inlet valve, an injector, an ejector for fuel gas circulation, a fuel gas pump for fuel gas circulation, and fuel gas piping, etc. The water storage part may be any that stores the liquid water contained in the anode off-gas discharged from the fuel cell, and may be a gas-liquid separator or the like. The drain pipe connects the water storage part and the cathode off-gas pipe. The drain pipe may have a drain valve for controlling drainage, or may have an exhaust and drainage valve for controlling exhaust and drainage. The drain pipe may be an exhaust and drain pipe. The drain pipe only needs to be connected below the cathode off-gas pipe. It may be connected below the cathode off-gas pipe in a cross-sectional view of the cathode off-gas pipe, or may be connected in such a way as to be tangent to the cathode off-gas pipe below the cathode off-gas pipe in a cross-sectional view of the cathode off-gas pipe. The drain pipe only needs to be inclined at an angle greater than or equal to the maximum allowable inclination angle of the vehicle at sub-zero temperatures with respect to the horizontal direction, or may be inclined at the maximum allowable inclination angle of the vehicle at sub-zero temperatures.

[0020] The oxidant gas system supplies oxidant gas to the fuel cell and adjusts the flow rate of the oxidant gas. The oxidant gas system includes a cathode off-gas pipe. The oxidant gas system may also include an oxidant gas supply means, a cathode gas supply pipe, an inlet-side sealing valve at the oxidant gas inlet of the fuel cell, an outlet-side sealing valve at the oxidant gas outlet of the fuel cell, etc. The cathode off-gas pipe allows the cathode off-gas discharged from the fuel cell to flow through. The oxidant gas supply means may be an air compressor or the like.

[0021] The cooling system supplies cooling water as a cooling medium to the fuel cell. The cooling water includes water, ethylene glycol, etc., and may be a mixture thereof or the like. The cooling system may include a cooling water pump, a reserve tank, a cooling flow path, a radiator, a bypass flow path, a rotary valve, an ion exchanger, an intercooler, etc. The cooling water pump circulates the cooling water for cooling the fuel cell and adjusts the flow rate of the cooling water supplied to the fuel cell. The reserve tank is a tank that temporarily stores the cooling water overflowing from the cooling flow path whose internal pressure has increased due to the temperature rise of the cooling water. The cooling flow path is a flow path that circulates the cooling water for cooling the fuel cell inside and outside the fuel cell. The radiator is disposed on the cooling flow path and cools the cooling water. The bypass flow path branches from the cooling flow path upstream of the radiator of the cooling flow path, bypasses the radiator, and merges with the cooling flow path downstream of the radiator of the cooling flow path. The rotary valve is disposed at the branch point from the cooling flow path to the bypass flow path. The rotary valve performs a flow path switching for switching whether the cooling water discharged from the fuel cell flows to the radiator or the bypass flow path. The rotary valve may include an electric motor such as an electric actuator for performing the flow path switching.

[0022] The fuel cell system may include a secondary battery. The secondary battery may be any rechargeable battery, and examples include conventionally known secondary batteries such as nickel-metal hydride secondary batteries and lithium-ion secondary batteries. Further, the secondary battery may include a power storage element such as an electric double layer capacitor. The secondary battery may be configured by connecting a plurality of them in series. The secondary battery supplies power to an air compressor or the like. The secondary battery may be rechargeable from an external power source of the fuel cell system such as a household power source, for example. The secondary battery may be charged by the output of the fuel cell. The charging and discharging of the secondary battery may be controlled by a control device.

[0023] The fuel cell system may include a control device. The control device may control the oxidant gas system, the fuel gas system, the cooling system, etc., and control the entire fuel cell system. Physically, the control device is, for example, an arithmetic processing device such as a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program and control data processed by the CPU, and a RAM (Random Access Memory) mainly used as various work areas for control processing. It may be an ECU (Electronic Control Unit) or the like.

Explanation of Signs

[0024] 10 Fuel cell 20 Fuel gas system 21 Drain pipe 22 Drain valve 23 Water storage section 30 Oxidant gas system 31 Cathode off-gas pipe

Claims

【Claim 1】 A fuel cell system for a vehicle, comprising: the fuel cell system includes: a fuel cell; a water storage section for storing liquid water contained in anode off-gas discharged from the fuel cell; a cathode off-gas pipe through which cathode off-gas discharged from the fuel cell flows; a drain pipe connecting the water storage section and the cathode off-gas pipe, and the drain pipe is connected below the cathode off-gas pipe, wherein the drain pipe is inclined at an angle greater than or equal to the maximum allowable inclination angle of the vehicle at sub-zero temperatures with respect to the horizontal direction. A fuel cell system.

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