fuel cell system

Abstract

To provide a fuel cell system that can prevent the solenoid from increasing in size.SOLUTION: In a fuel gas system, a fuel cell system includes an outward-opening valve type first fuel supply device, a second fuel supply device with an inward opening valve, and a fuel gas supply pressure sensor, and when the fuel gas supply pressure is excessive, the first fuel supply device operates the fuel cell, and when the fuel gas supply pressure is normal, the fuel cell is operated using the first fuel supply device and the second fuel supply device in combination.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to fuel cell systems. [Background technology]

[0002] Various researches are being conducted on fuel cells (FC). For example, Patent Document 1 discloses an FC system that has an ON / OFF controlled injector (INJ) and an opening-controllable linear solenoid valve (LSV), and controls the fuel supply device to be used by switching it according to the FC load, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-087520 Summary of the Invention [Problem to be solved by the invention]

[0004] If the fuel supplier is provided with a solenoid as a component of an internally opening valve type fuel supplier such as an injector, which is used when the fuel gas supply pressure is excessive, the size of the fuel supplier will increase.

[0005] The present disclosure has been made in consideration of the above-mentioned situation, and its main purpose is to provide a fuel cell system that can prevent the solenoid from becoming larger by preventing an internal opening valve type fuel supply device from opening when the fuel gas supply pressure becomes excessive. [Means for solving the problem]

[0006] In the present disclosure, a fuel gas system includes a first fuel supplier having an outer valve, a second fuel supplier having an inner valve, and a fuel gas supply pressure sensor, When the fuel gas supply pressure is excessive, the fuel cell is operated by the first fuel supplier; When the fuel gas supply pressure is normal, the fuel cell is operated by using both the first fuel supplier and the second fuel supplier.

[0007] In the fuel cell system of the present disclosure, the first fuel supplier is a linear solenoid valve, The second fuel supplier may be an injector.

[0008] The fuel cell system of the present disclosure further includes a control unit, the control unit determines whether the fuel gas supply pressure measured by the fuel gas supply pressure sensor exceeds a predetermined threshold value; the control unit determines that the fuel gas supply pressure is excessive when the fuel gas supply pressure measured by the fuel gas supply pressure sensor exceeds a predetermined threshold, and operates the fuel cell using the first fuel supplier; When the fuel gas supply pressure measured by the fuel gas supply pressure sensor is below a predetermined threshold, the control unit may determine that the fuel gas supply pressure is normal and operate the fuel cell using both the first fuel supply device and the second fuel supply device. [Effects of the Invention]

[0009] The present disclosure can provide a fuel cell system that can prevent the solenoid from becoming large. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing an example of a fuel cell system according to the present disclosure. [Figure 2] FIG. 2 is a flowchart showing an example of control of the fuel cell system of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiments of the present disclosure will be described below. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of a fuel cell system that do not characterize the present disclosure) can be understood as design matters for those skilled in the art based on prior art in the relevant field. The present disclosure can be implemented based on the contents disclosed in this specification and common general technical knowledge in the relevant field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships. In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. Any combination of upper and lower limits in the numerical range can be adopted.

[0012] In the present disclosure, a fuel gas system includes a first fuel supplier having an outer valve, a second fuel supplier having an inner valve, and a fuel gas supply pressure sensor, When the fuel gas supply pressure is excessive, the fuel cell is operated by the first fuel supplier; When the fuel gas supply pressure is normal, the fuel cell is operated by using both the first fuel supplier and the second fuel supplier.

[0013] Conventional technology requires an injector that can open even when the fuel gas supply pressure (≒ relief pressure on the primary side of the injector) exceeds the normal operating pressure. However, if the injector is equipped with a solenoid that can open even at a high primary pressure, the size of the injector will increase. When a fuel cell system is left unused for an extended period of time, the primary pressure may become excessive due to fuel gas passing through the pressure reducing valve (regulator). When the primary pressure exceeds a predetermined value, the relief valve opens to reduce the pressure. However, since the relief valve only releases fuel gas into the atmosphere when the primary pressure exceeds a predetermined value, conventional technology does not have a mechanism to safely release and regulate excessive primary pressure. Therefore, the fuel cell system disclosed herein is configured to include a first fuel supply device with an externally opening valve (e.g., a linear solenoid valve, etc.) and a second fuel supply device with an internally opening valve (e.g., an injector, etc.) as fuel supply devices, and when the fuel gas supply pressure becomes excessive (when the primary pressure exceeds the normal pressure due to permeation through the pressure reducing valve after being left unused for a long period of time), the system first starts up using the first fuel supply device with an externally opening valve, and then transitions to normal control after optimizing the fuel gas supply pressure.

[0014] In this disclosure, fuel gas and oxidant gas are collectively referred to as reactant gases. The reactant gas supplied to the anode is fuel gas (anode gas), and the reactant gas supplied to the cathode is oxidant gas (cathode gas). The fuel gas is a gas that mainly contains hydrogen and may be hydrogen. The oxidant gas is a gas that contains oxygen and may be air or the like.

[0015] The fuel cell system of the present disclosure may be mounted on a moving body such as a vehicle. The vehicle may be a fuel cell vehicle, etc. Examples of moving bodies other than vehicles include trains, ships, and aircraft. The fuel cell system of the present disclosure may also be mounted on a mobile object such as a vehicle that can run on power from a secondary battery. A mobile object may include the fuel cell system of the present disclosure, and may have a drive unit such as a motor, an inverter, a hybrid control system, etc. The hybrid control system may be capable of running a mobile object using both the output of the fuel cell and the power of the secondary battery.

[0016] The fuel cell system of the present disclosure includes, in its fuel gas system, a first fuel supplier with an externally opening valve, a second fuel supplier with an internally opening valve, and a fuel gas supply pressure sensor, and may also include, as necessary, a relief valve, an ejector, a gas-liquid separator, an exhaust drain valve, an anode gas passage, an anode off-gas passage, and a circulation path connecting the anode gas passage and the anode off-gas passage. The fuel gas system may have a relief valve, a fuel gas supply pressure sensor, and an ejector, in that order, upstream of the fuel cell (in the anode gas passage), a first fuel supplier with an externally opening valve and a second fuel supplier with an internally opening valve disposed downstream of the relief valve and upstream of the ejector, and a gas-liquid separator and an exhaust / drain valve downstream of the fuel cell (in the anode off-gas passage), with the ejector and the gas-liquid separator connected by a circulation path, allowing the fuel gas to circulate within the fuel gas system. The fuel gas supply pressure sensor may be provided upstream of the first fuel supplier with an externally opening valve and the second fuel supplier with an internally opening valve. The first fuel supplier with an externally opening valve and the second fuel supplier with an internally opening valve may be disposed in parallel. The fuel cell system of the present disclosure includes a fuel gas system, and typically includes an oxidant gas system and a cooling system. The fuel gas system supplies fuel gas to at least the anode of the fuel cell, and circulates within the fuel gas system or discharges outside the fuel gas system, as needed, fuel off-gas (anode off-gas), which is the reacted fuel gas discharged from the anode of the fuel cell. The oxidant gas system supplies oxidant gas to at least the cathode of the fuel cell, and discharges outside the oxidant gas system, as needed, oxidant off-gas (cathode off-gas), which is the reacted oxidant gas discharged from the cathode of the fuel cell. The cooling system supplies a cooling medium to at least the fuel cell, and circulates the cooling medium inside and outside the fuel cell as needed to adjust the temperature of the fuel cell. The fuel off-gas may contain fuel gas that has passed through the anode without reacting, water that has been produced at the cathode and has reached the anode, etc. The fuel off-gas may also contain corrosive substances produced in the catalyst layer, the electrolyte membrane, etc., and an oxidant gas that may be supplied to the anode during scavenging.

[0017] An example of an externally opening valve type first fuel supplier is a linear solenoid valve. Since the fuel gas supply pressure acts in the valve opening direction, the externally opening valve can be opened with a small electromagnetic force when the fuel gas supply pressure is excessive. An example of the inward-opening valve type second fuel supplier is an injector, etc. The inward-opening valve is difficult to open when the fuel gas supply pressure is excessive because the fuel gas supply pressure acts in the valve closing direction.

[0018] The fuel gas supply pressure sensor may be a conventionally known pressure gauge or the like. The fuel gas supply pressure sensor may be disposed upstream of an externally opening valve type first fuel supplier in the fuel gas system, or may be disposed upstream of an internally opening valve type second fuel supplier. The fuel gas supply pressure sensor detects the fuel gas supply pressure in the fuel gas system. The fuel gas supply pressure sensor may be electrically connected to a control unit. The control unit detects the pressure obtained by the fuel gas supply pressure sensor.

[0019] A relief valve is a mechanism that releases gases such as fuel gas to the atmosphere when the primary pressure becomes excessive due to factors such as fuel gas permeation through the pressure reducing valve. To prevent unnecessary release of gas to the atmosphere, the opening pressure of a relief valve is usually set higher than the normal primary pressure.

[0020] The fuel cell system of the present disclosure may have a control unit. The control unit physically includes, for example, a processing unit such as a CPU (Central Processing Unit), a storage device such as a ROM (Read Only Memory) that stores control programs and control data processed by the CPU, a RAM (Random Access Memory) that is used mainly as various work areas for control processing, and an input / output interface. The control unit may also be, for example, a control device such as an Electronic Control Unit (ECU). The control unit may be electrically connected to an ignition switch that may be mounted on a moving object such as a vehicle, and the control unit may be operable by an external power source even when the ignition switch is turned off.

[0021] The fuel cell system of the present disclosure may include a fuel cell, which may include only one unit cell, or may be a fuel cell stack, which is a stack of multiple unit cells. In this disclosure, both a single cell and a fuel cell stack may be referred to as a fuel cell. The number of stacked unit cells is not particularly limited, and may be, for example, from 2 to several hundred.

[0022] A single cell of the fuel cell comprises at least a membrane electrode gas diffusion layer assembly. The membrane electrode gas diffusion layer assembly has, in this order, an anode gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, and a cathode gas diffusion layer.

[0023] The cathode (oxidant electrode) includes a cathode catalyst layer and a cathode-side gas diffusion layer. The anode (fuel electrode) includes an anode catalyst layer and an anode-side gas diffusion layer. The cathode catalyst layer and the anode catalyst layer are collectively referred to as the catalyst layer. Examples of the anode catalyst and the cathode catalyst include platinum (Pt) and ruthenium (Ru), and examples of the carrier that supports the catalyst include carbon materials such as carbon.

[0024] The cathode side gas diffusion layer and the anode side gas diffusion layer are collectively referred to as gas diffusion layers. The gas diffusion layer may be a gas-permeable conductive material or the like. Examples of the conductive member include porous carbon materials such as carbon cloth and carbon paper, and porous metal materials such as metal mesh and foam metal.

[0025] The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include a fluorine-based electrolyte membrane such as a thin film of perfluorosulfonic acid containing water, and a hydrocarbon-based electrolyte membrane. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by DuPont).

[0026] The single cell may optionally include two separators sandwiching both sides of the membrane electrode gas diffusion layer assembly. One of the two separators is an anode-side separator, and the other is a cathode-side separator. In the present disclosure, the anode-side separator and the cathode-side separator are collectively referred to as separators. The separator may have holes that constitute manifolds, such as supply holes and discharge holes, for passing fluids such as reaction gases and cooling media in the stacking direction of the unit cells. As the cooling medium, for example, a mixed solution of ethylene glycol and water can be used to prevent freezing at low temperatures. Examples of the supply holes include a fuel gas supply hole, an oxidant gas supply hole, and a coolant supply hole. Examples of the exhaust hole include a fuel gas exhaust hole, an oxidant gas exhaust hole, and a coolant exhaust hole. The separator may have a reactant gas flow path on the surface in contact with the gas diffusion layer, and may have a coolant flow path on the surface opposite to the surface in contact with the gas diffusion layer to maintain a constant temperature of the fuel cell. The separator may be a gas-impermeable conductive material. Examples of the conductive material include dense carbon made by compressing carbon to make it gas-impermeable, and press-formed metal (e.g., iron, aluminum, stainless steel, etc.) plates. The separator may also have a current collecting function.

[0027] The fuel cell stack may have manifolds such as an inlet manifold to which each of the supply holes communicates, and an outlet manifold to which each of the discharge holes communicates. 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 coolant outlet manifold.

[0028] Fig. 1 is a schematic diagram showing an example of a fuel cell system according to the present disclosure. For the sake of simplicity, the oxidant gas system and cooling system of the fuel cell system shown in Fig. 1 are omitted. The fuel cell system shown in Fig. 1 includes a fuel cell (FC) stack and a fuel gas system. The fuel gas system has a relief valve and an ejector in that order upstream of the fuel cell (anode gas passage), an injector and a linear solenoid valve arranged in parallel downstream of the relief valve and upstream of the ejector, a fuel gas supply pressure sensor arranged downstream of the relief valve and upstream of the injector and linear solenoid valve, a gas-liquid separator and an exhaust drain valve downstream of the fuel cell (anode off-gas passage), the ejector and gas-liquid separator are connected by a circulation path, and a circulation system is constructed that allows fuel gas to circulate within the fuel gas system.

[0029] An example of control of the fuel cell system of the present disclosure is as follows. In the fuel cell system of the present disclosure, when the fuel gas supply pressure is excessive, the fuel cell is operated using the first fuel supplier (which opens easily at high pressure), and when the fuel gas supply pressure is normal, the fuel cell is operated using both the first fuel supplier and the second fuel supplier. That is, in the fuel cell system of the present disclosure, when the fuel gas supply pressure sensor value exceeds the normal pressure, the externally opening valve type first fuel supply device (LSV) is driven to operate the FC. When the fuel gas supply pressure falls within the normal pressure range, normal control is performed using both the internally opening valve type second fuel supply device (INJ) and the externally opening valve type first fuel supply device (LSV). As a result, the inward-opening valve type second fuel supply device does not need to open at a pressure higher than normal pressure, and therefore it is possible to prevent the solenoid, which is a component of the inward-opening valve type second fuel supply device, from becoming larger.

[0030] FIG. 2 is a flowchart showing an example of control of the fuel cell system of the present disclosure. The control unit determines whether or not the fuel gas supply pressure (supply pressure sensor value) measured by the fuel gas supply pressure sensor exceeds a predetermined threshold value (normal pressure). When the fuel gas supply pressure measured by the fuel gas supply pressure sensor exceeds a predetermined threshold, the control unit determines that the fuel gas supply pressure is excessively high, and operates the fuel cell using the first fuel supplier. When the fuel gas supply pressure measured by the fuel gas supply pressure sensor is equal to or lower than a predetermined threshold, the control unit determines that the fuel gas supply pressure is normal and operates the fuel cell using both the first fuel supplier and the second fuel supplier.

Claims

[Claim 1] A control unit, and in a fuel gas system, a first fuel supply device with an externally opening valve, a second fuel supply device with an internally opening valve, and a fuel gas supply pressure sensor; the first fuel supplier is a linear solenoid valve; the second fuel supplier is an injector, the control unit determines whether the fuel gas supply pressure measured by the fuel gas supply pressure sensor exceeds a predetermined threshold value; the control unit determines that the fuel gas supply pressure is excessive when the fuel gas supply pressure measured by the fuel gas supply pressure sensor exceeds a predetermined threshold, and operates the fuel cell using the first fuel supplier; When the fuel gas supply pressure measured by the fuel gas supply pressure sensor is below a predetermined threshold, the control unit determines that the fuel gas supply pressure is normal and operates the fuel cell using both the first fuel supply device and the second fuel supply device.

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