Air-cooled fuel cell system

Abstract

The present invention provides an air-cooled fuel cell system capable of suppressing thermal runaway. The air-cooled fuel cell system comprises a fuel cell, a first temperature acquisition unit, a second temperature acquisition unit, and a control unit. The fuel cell has metal cooling fins. The first temperature acquisition unit is located near a cooling air inlet of the fuel cell and spaced apart from the cooling fins. The second temperature acquisition unit is located in contact with the cooling fins. The control unit monitors the temperatures acquired by the first and second temperature acquisition units and stops power generation by the fuel cell when the difference between the temperatures acquired by the first and second temperature acquisition units exceeds a predetermined temperature threshold, or when the difference between the temperature increase rates acquired by the first and second temperature acquisition units exceeds a predetermined temperature increase rate threshold.

Description

Technical Field

[0001] The present disclosure relates to an air-cooled fuel cell system. Background Art

[0002] A fuel cell (FC) is a power generation device consisting of a single cell (hereinafter sometimes referred to as a unit) or a fuel cell stack (hereinafter sometimes referred to as a cell stack) composed of multiple stacked cells. It generates electrical energy through the electrochemical reaction of a fuel gas such as hydrogen and an oxidant gas such as oxygen. In practice, the fuel gas and oxidant gas supplied to the fuel cell are often a mixture of gases that do not contribute to oxidation or reduction. In particular, the oxidant gas is often air containing oxygen.

[0003] In the following, fuel gas and oxidant gas may be simply referred to as "reactant gas" or "gas" without distinguishing between them. In addition, a single cell and a fuel cell stack formed by stacking single cells may be referred to as a fuel cell.

[0004] Various technologies have been proposed for fuel cells that are mounted on fuel cell vehicles (hereinafter sometimes referred to as vehicles) for use.

[0005] For example, Patent Document 1 discloses a new air-cooled fuel cell unit that improves cooling efficiency by equalizing the temperatures on the intake and exhaust sides of an FC cell stack.

[0006] Patent Document 2 discloses a fuel cell capable of detecting appropriate cell temperature.

[0007] Patent Document 3 discloses a fuel cell capable of early detecting various abnormalities that lead to a reduction in power generation capacity at a local level, and rapidly identifying and addressing the cause of the abnormality.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-106831

[0009] Patent Document 2: Japanese Patent Application Publication No. 2018-116861

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2008-123960

[0011] Fuel cells generally require a temperature of 100°C or less for stable power generation, although this depends on the materials used in their components. Therefore, accurately understanding the temperature is crucial to ensure that the power generation reaction is proceeding efficiently and that the temperature does not reach a level that could cause component problems.

[0012] Patent Document 1 discloses control for maintaining a desired power generation state, but does not allow for determining whether an abnormal state such as excessive temperature increase is present and for taking appropriate measures. Summary of the Invention

[0013] The present disclosure is made in view of the above-mentioned actual situation, and its main purpose is to provide an air-cooled fuel cell system capable of suppressing thermal runaway.

[0014] The air-cooled fuel cell system disclosed in the present invention is characterized in that the air-cooled fuel cell system comprises: a fuel cell; a first temperature acquisition unit; a second temperature acquisition unit; and a control unit, the fuel cell has metal cooling fins, the first temperature acquisition unit is arranged in the vicinity of the cooling air inlet of the fuel cell and at a position separated from the cooling fins, the second temperature acquisition unit is arranged in a manner abutting against the cooling fins, the control unit monitors the various temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit, and when the difference between the various temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature threshold, or when the difference between the various temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature rise rate threshold, the control unit stops power generation of the fuel cell.

[0015] On the basis of the air-cooled fuel cell system disclosed in the present invention, the air-cooled fuel cell system further comprises: an air inlet portion for introducing air from the outside of the air-cooled fuel cell system; a reaction air supply portion for supplying the reaction air to the fuel cell; a reaction air supply flow path for connecting the reaction air supply portion with the reaction air inlet of the fuel cell; a reaction air exhaust flow path for connecting the reaction air outlet of the fuel cell with the outside; a cooling air supply flow path for connecting the air inlet portion with the cooling air inlet of the fuel cell; a fuel gas supply portion for supplying fuel gas to the fuel cell; a fuel gas supply flow path for connecting the fuel gas supply portion with the fuel gas inlet of the fuel cell; and a fuel exhaust gas exhaust flow path for connecting the fuel gas outlet of the fuel cell with the outside. The fuel cell comprises a reaction air manifold and The cooling air manifold has an independent structure, the reaction air supply flow path has a first valve in an area downstream of the reaction air supply part and upstream of the reaction air inlet of the fuel cell, the reaction air exhaust flow path has a second valve downstream of the reaction air outlet of the fuel cell, the fuel gas supply flow path has a third valve upstream of the fuel gas inlet of the fuel cell, and the fuel exhaust gas exhaust flow path has a fourth valve downstream of the fuel gas outlet of the fuel cell. When the difference between the temperatures obtained by the first temperature acquisition part and the second temperature acquisition part is greater than a specified temperature threshold, or when the difference between the temperature rise rates obtained by the first temperature acquisition part and the second temperature acquisition part is greater than a specified temperature rise rate threshold, the control part reduces the openings of the first valve, the second valve, the third valve and the fourth valve.

[0016] According to the air-cooled fuel cell system of the present disclosure, thermal runaway can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an exploded perspective view showing an example of a portion of the fuel cell disclosed herein.

[0018] Figure 2 This is a schematic cross-sectional view showing an example of a portion of the fuel cell disclosed herein.

[0019] Figure 3 This is a schematic configuration diagram showing an example of an air-cooled fuel cell system of the present disclosure.

[0020] Figure 4 This is a schematic configuration diagram showing another example of the air-cooled fuel cell system disclosed herein.

[0021] Figure 5 This is a flowchart showing an example of control of the air-cooled fuel cell system of the present disclosure.

[0022] Description of Reference Numerals

[0023] 10…Fuel cell; 11…Single cell; 12…First separator; 13…Second separator; 14…Resin frame; 15…Cooling fin; 16…Gasket; 17…Manifold; 18…Assembly; 19…Current collector; 20…Air system; 21…Air inlet; 22…Reaction air inlet; 23…Cooling air inlet; 30…Oxidant gas system; 31…Filter; 32…Reaction air supply; 33…Reaction air supply flow path; 34…Reaction air exhaust flow path; 35…First valve; 36… 2nd valve; 37…reaction air bypass flow path; 40…cooling system; 41…cooling air supply flow path; 42…cooling air exhaust flow path; 43…refrigerant drive unit; 50…fuel gas system; 51…fuel gas supply unit; 52…fuel gas supply flow path; 53…fuel waste gas exhaust flow path; 54…circulation flow path; 55…gas-liquid separator; 56…gas circulation pump; 57…3rd valve; 58…4th valve; 59…ejector; 60…control unit; T1…first temperature acquisition unit; T2…second temperature acquisition unit. DETAILED DESCRIPTION

[0024] The air-cooled fuel cell system disclosed in the present invention is characterized in that the air-cooled fuel cell system comprises: a fuel cell; a first temperature acquisition unit; a second temperature acquisition unit; and a control unit, the fuel cell has metal cooling fins, the first temperature acquisition unit is arranged in the vicinity of the cooling air inlet of the fuel cell and at a position separated from the cooling fins, the second temperature acquisition unit is arranged in a manner abutting against the cooling fins, the control unit monitors the various temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit, and when the difference between the various temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature threshold, or when the difference between the various temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature rise rate threshold, the control unit stops power generation of the fuel cell.

[0025] Compared to water-cooled fuel cells, air-cooled fuel cells have a smaller thermal capacity and poorer heat transfer to the air. Therefore, if an abnormality occurs, such as a decrease in cooling flow, there is a greater risk of excessive temperature rise. It is crucial to quickly detect such an abnormality and safely control the fuel cell's power generation.

[0026] In a water-cooled fuel cell, water conducts heat better and the fuel cell has a larger heat capacity, so the temperature rise rate is slower and the need for urgent detection, as in an air-cooled fuel cell, is less.

[0027] According to the present disclosure, by monitoring the temperature difference between the temperature of air not in contact with the fuel cell and the temperature inside the fuel cell, abnormalities inside the fuel cell during power generation can be more accurately detected and the presence of abnormalities in the fuel cell can be determined based on the temperature difference.

[0028] According to the present disclosure, the temperature difference or temperature rise rate difference inside and outside the air-cooled fuel cell can be accurately grasped, so that excessive temperature rise in the air-cooled fuel cell with a small heat capacity of the refrigerant can be quickly detected, thereby avoiding or suppressing thermal runaway.

[0029] In air-cooled fuel cells, measuring the temperature of the air outside the fuel cell suffers from poor heat transfer, making abnormality detection time-consuming. According to the present disclosure, by creating a structure where the temperature sensor is in direct contact with the metal cooling fins, the cooling fin temperature can be directly measured even when the cooling air supply is stopped, thereby accurately determining the fuel cell temperature.

[0030] The fuel cell system disclosed herein is an air-cooled fuel cell system.

[0031] Air-cooled fuel cell systems use air as a refrigerant. In this disclosure, air used as a refrigerant is sometimes referred to as cooling air. In this disclosure, air used as an oxidant gas is sometimes referred to as reaction air.

[0032] The air-cooled fuel cell system includes a fuel cell, a first temperature acquisition unit, a second temperature acquisition unit, a control unit, and the like.

[0033] A fuel cell generally has single cells.

[0034] The fuel cell may have only one unit cell, or may be a fuel cell stack that is a stack formed by stacking a plurality of unit cells.

[0035] The number of stacked cells is not particularly limited, and may be, for example, 2 to several hundred, 20 to 600, or 40 to 200.

[0036] The fuel cell stack may include end plates, current collecting plates, pressure plates, and the like at both ends of the stacking direction of the single cells.

[0037] The fuel cell may include a membrane electrode gas diffusion layer assembly (MEGA). The fuel cell may include a first separator and a second separator sandwiching the membrane electrode gas diffusion layer assembly.

[0038] The membrane electrode gas diffusion layer assembly includes a first gas diffusion layer, a first catalyst layer, an electrolyte membrane, a second catalyst layer, and a second gas diffusion layer in this order.

[0039] Specifically, the membrane electrode gas diffusion layer assembly includes an anode-side gas diffusion layer, an anode catalyst layer, an electrolyte membrane, a cathode catalyst layer, and a cathode-side gas diffusion layer in this order.

[0040] One of the first catalyst layer and the second catalyst layer is a cathode catalyst layer, and the other is an anode catalyst layer.

[0041] The cathode (oxidant electrode) includes a cathode catalyst layer and a cathode-side gas diffusion layer.

[0042] The anode (fuel electrode) includes an anode catalyst layer and an anode-side gas diffusion layer.

[0043] The first catalyst layer and the second catalyst layer are collectively referred to as catalyst layers. The cathode catalyst layer and the anode catalyst layer are collectively referred to as catalyst layers.

[0044] One of the first gas diffusion layer and the second gas diffusion layer is a cathode-side gas diffusion layer, and the other is an anode-side gas diffusion layer.

[0045] When the first catalyst layer is a cathode catalyst layer, the first gas diffusion layer is a cathode-side gas diffusion layer. When the first catalyst layer is an anode catalyst layer, the first gas diffusion layer is an anode-side gas diffusion layer.

[0046] When the second catalyst layer is a cathode catalyst layer, the second gas diffusion layer is a cathode-side gas diffusion layer. When the second catalyst layer is an anode catalyst layer, the second gas diffusion layer is an anode-side gas diffusion layer.

[0047] The first gas diffusion layer and the second gas diffusion layer are collectively referred to as gas diffusion layers or diffusion layers. The cathode-side gas diffusion layer and the anode-side gas diffusion layer are collectively referred to as gas diffusion layers or diffusion layers.

[0048] The gas diffusion layer may be a gas-permeable conductive member or the like.

[0049] Examples of the conductive member include carbon porous materials such as carbon cloth and carbon paper, and metal porous materials such as metal mesh and foamed metal.

[0050] The fuel cell may also include a microporous layer (MPL) between the catalyst layer and the gas diffusion layer. The microporous layer may also include a mixture of a hydrophobic resin such as PTFE and a conductive material such as carbon black.

[0051] The electrolyte membrane may also be a solid polymer electrolyte membrane. Examples of solid polymer electrolyte membranes include fluorine-based electrolyte membranes such as a thin film of perfluorosulfonic acid containing water, and hydrocarbon-based electrolyte membranes. Examples of electrolyte membranes include perfluorosulfonic acid membranes (manufactured by DuPont).

[0052] One of the first separator and the second separator is a cathode-side separator, and the other is an anode-side separator.

[0053] When the first catalyst layer is a cathode catalyst layer, the first separator is a cathode-side separator. When the first catalyst layer is an anode catalyst layer, the first separator is an anode-side separator.

[0054] When the second catalyst layer is a cathode catalyst layer, the second separator is a cathode-side separator. When the second catalyst layer is an anode catalyst layer, the second separator is an anode-side separator.

[0055] The first separator and the second separator are collectively referred to as separators. The anode-side separator and the cathode-side separator are collectively referred to as separators.

[0056] The membrane electrode gas diffusion layer assembly is sandwiched between the first separator and the second separator.

[0057] The separator may have supply holes and discharge holes for allowing fluids such as reaction gas and refrigerant to flow in the stacking direction of the cells. In the case of gas, cooling air or the like can be used as the refrigerant.

[0058] Examples of the supply holes include fuel gas supply holes, oxidant gas supply holes, and refrigerant supply holes.

[0059] Examples of the discharge holes include a fuel gas discharge hole, an oxidant gas discharge hole, and a refrigerant discharge hole.

[0060] The isolation member may have one or more fuel gas supply holes, one or more oxidant gas supply holes, one or more refrigerant supply holes as needed, one or more fuel gas discharge holes, one or more oxidant gas discharge holes, and one or more refrigerant discharge holes as needed.

[0061] The separator may have a reaction gas flow path on the surface in contact with the gas diffusion layer. Alternatively, the separator may have a coolant flow path on the surface opposite to the surface in contact with the gas diffusion layer for maintaining a constant temperature of the fuel cell.

[0062] In the case where the separator is an anode side separator, it may have one or more fuel gas supply holes, one or more oxidant gas supply holes, one or more refrigerant supply holes as needed, one or more fuel gas discharge holes, one or more oxidant gas discharge holes, and one or more refrigerant discharge holes as needed. The anode side separator may have a fuel gas flow path on the surface in contact with the anode side gas diffusion layer for allowing the fuel gas to flow from the fuel gas supply hole to the fuel gas discharge hole, and may also have a refrigerant flow path on the surface opposite to the surface in contact with the anode side gas diffusion layer for allowing the refrigerant to flow from the refrigerant supply hole to the refrigerant discharge hole as needed.

[0063] In the case where the separator is a cathode side separator, it may have one or more fuel gas supply holes, one or more oxidant gas supply holes, one or more refrigerant supply holes as needed, one or more fuel gas discharge holes, one or more oxidant gas discharge holes, and one or more refrigerant discharge holes as needed. The cathode side separator may have an oxidant gas flow path on the surface in contact with the cathode side gas diffusion layer for allowing the oxidant gas to flow from the oxidant gas supply hole to the oxidant gas discharge hole, and may also have a refrigerant flow path on the surface opposite to the surface in contact with the cathode side gas diffusion layer for allowing the refrigerant to flow from the refrigerant supply hole to the refrigerant discharge hole as needed.

[0064] The separator may also be an airtight conductive member. Examples of the conductive member include resin materials such as thermosetting resins, thermoplastic resins, and resin fibers; carbon composite materials obtained by stamping a mixture containing carbon materials such as carbon powder and carbon fibers; dense carbon obtained by compressing carbon to form an airtight material; and stamped metal plates (e.g., titanium, iron, aluminum, and SUS). Furthermore, the separator may also have a current collecting function.

[0065] The shape of the spacer may be a rectangle, a horizontally long hexagon, a horizontally long octagon, a circle, an oval, or the like.

[0066] The fuel cell may include a manifold such as an inlet manifold through which the supply holes communicate and an outlet manifold through which the discharge holes communicate.

[0067] Examples of the inlet manifold include an anode inlet manifold, a reaction air inlet manifold (cathode inlet manifold), and a cooling air inlet manifold.

[0068] Examples of the outlet manifold include an anode outlet manifold, a reaction air outlet manifold (cathode outlet manifold), and a cooling air outlet manifold.

[0069] In the present disclosure, the reaction air inlet manifold (cathode inlet manifold) and the reaction air outlet manifold (cathode outlet manifold) are collectively referred to as a reaction air manifold.

[0070] In this disclosure, the cooling air inlet manifold and the cooling air outlet manifold are collectively referred to as a cooling air manifold.

[0071] The fuel cell has a structure in which the reaction air manifold and the cooling air manifold are independent.

[0072] 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, and the reactant gas supplied to the cathode is oxidant gas. Fuel gas is primarily hydrogen-containing gas, but may also be hydrogen. Oxidant gas may also be oxygen, air, dry air, or the like.

[0073] The fuel cell may also include a resin frame.

[0074] The resin frame may be arranged on the outer periphery of the membrane electrode gas diffusion layer assembly and between the first separator and the second separator.

[0075] Furthermore, the resin frame may be a member for preventing cross leakage or electrical short circuit between catalyst layers of the membrane electrode gas diffusion layer assembly.

[0076] The resin frame may have a skeleton portion, an opening, a supply hole, and a discharge hole.

[0077] The skeleton portion is the main part of the resin frame connected to the membrane electrode gas diffusion layer assembly.

[0078] The opening serves as a holding area for the membrane electrode gas diffusion layer assembly and is a through-hole extending through a portion of the frame portion to accommodate the membrane electrode gas diffusion layer assembly. The opening may be located in the resin frame at a position where the frame portion is disposed around (at the periphery of) the membrane electrode gas diffusion layer assembly, or may be located in the center of the resin frame.

[0079] The supply and exhaust holes allow the flow of reactant gases, refrigerant, and the like in the stacking direction of the cells. The supply holes of the resin frame can also be aligned and arranged to communicate with the supply holes of the separator. The exhaust holes of the resin frame can also be aligned and arranged to communicate with the exhaust holes of the separator.

[0080] The resin frame may include a frame-shaped core layer and two frame-shaped shell layers provided on both surfaces of the core layer, that is, a first shell layer and a second shell layer.

[0081] The first shell layer and the second shell layer may be provided in a frame shape on both surfaces of the core layer, similarly to the core layer.

[0082] The core layer can be any structural component that is gas-tight and insulating, and can be formed from a material whose structure does not change even under the temperature conditions of hot pressing during the fuel cell manufacturing process. Specifically, the core layer material can be, for example, polyethylene, polypropylene, PC (polycarbonate), PPS (polyphenylene sulfide), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PA (polyamide), PI (polyimide), PS (polystyrene), PPE (polyphenylene ether), PEEK (polyetheretherketone), cycloolefin, PES (polyethersulfone), PPSU (polyphenylsulfone), LCP (liquid crystal polymer), epoxy resin, and the like. The core layer material can also be a rubber material such as EPDM (ethylene propylene diene monomer), fluororubber, or silicone rubber.

[0083] From the viewpoint of ensuring insulation properties, the thickness of the core layer may be 5 μm or more, or 30 μm or more. From the viewpoint of reducing the cell thickness, the thickness may be 200 μm or less, or 150 μm or less.

[0084] To ensure sealing by bonding the core layer to the anode-side separator and cathode-side separator, the first and second shell layers have high adhesion to other materials, soften under the temperature conditions of hot pressing, and have lower viscosity and melting points than the core layer. Specifically, the first and second shell layers can be made of thermoplastic resins such as polyesters and modified olefins, or thermosetting resins such as modified epoxy resins. The first and second shell layers can also be made of the same resin as the adhesive layer.

[0085] The resin constituting the first shell layer and the resin constituting the second shell layer may be the same type of resin or different types of resin. Providing the shell layers on both sides of the core layer facilitates the bonding of the resin frame and the two spacers by heat pressing.

[0086] From the perspective of ensuring adhesion, the thickness of each of the first and second shell layers may be 5 μm or more, or 20 μm or more. From the perspective of reducing the cell thickness, the thickness may be 100 μm or less, or 40 μm or less.

[0087] In the resin frame, the first and second shell layers may be provided only on the portions bonded to the anode-side separator and cathode-side separator, respectively. The first shell layer provided on one surface of the core layer may also be bonded to the cathode-side separator. The second shell layer provided on the other surface of the core layer may also be bonded to the anode-side separator. Furthermore, the resin frame may be sandwiched between a pair of separators.

[0088] The fuel cell may include a gasket between two adjacent single cells.

[0089] The gasket may be made of ethylene propylene diene monomer (EPDM), silicone rubber, thermoplastic elastomer resin, or the like.

[0090] The fuel cell has cooling fins made of metal. Examples of the metal include Al, Ti, and SUS. The fuel cell may also have cooling fins between two adjacent cells.

[0091] When the separator is made of, for example, a carbon composite material, the heat conduction is poorer than when it is made of a metal material. To compensate for this, metal cooling fins are provided, thereby enabling detection of abnormal heating over a large area within the fuel cell.

[0092] The cooling fins may be corrugated plates having a plurality of grooves functioning as refrigerant flow paths.

[0093] The cooling fins may be made of, for example, a metal plate bent into a corrugated shape. The cooling fins may also be subjected to a conductive treatment such as silver, nickel, or carbon on the surface.

[0094] The grooves of the cooling fins can also be formed by bending.

[0095] The depth of the groove may be, for example, 1.0 to 2.0 mm.

[0096] The bending process may be performed to form concave and convex grooves with a depth of 1.0 to 2.0 mm and a width of 1.0 to 2.0 mm, for example.

[0097] The cooling fins may be arranged in at least a portion of the area in the plane direction between the two adjacent single cells, as long as they are arranged between the two adjacent single cells.

[0098] The cooling fins may be arranged at least in a region facing the MEGA between two adjacent cells in the planar direction.

[0099] The cooling fins may be arranged in a region other than the region where the gasket is arranged between two adjacent single cells in the planar direction.

[0100] The cooling fins may have protrusions that protrude from the outer shape of the battery cells.

[0101] The cooling fins may also be in the shape of a rectangle, a horizontally long hexagon, a horizontally long octagon, a circle, an oval, or the like.

[0102] The first temperature acquisition unit is disposed near the cooling air inlet of the fuel cell and at a position separated from the cooling fins.

[0103] The first temperature acquisition unit measures the temperature of cooling air flowing in from the outside.

[0104] The first temperature acquisition unit is electrically connected to the control unit, and the control unit detects the temperature of the cooling air flowing in from the outside measured by the first temperature acquisition unit.

[0105] As the first temperature acquisition unit, a conventionally known temperature sensor, thermometer, or the like can be used.

[0106] If the first temperature acquisition unit comes into contact with a fuel cell component, the temperature will change due to the increase in the fuel cell temperature. Therefore, the first temperature acquisition unit is thermally separated from the fuel cell component to accurately measure the temperature of cooling air flowing in from the outside.

[0107] The first temperature acquisition unit is not particularly limited in its placement position as long as it can measure a temperature equivalent to the inflow temperature of the cooling air into the fuel cell system.

[0108] The second temperature acquisition unit is arranged so as to come into contact with the cooling fins.

[0109] The second temperature acquisition unit measures the temperature of the fuel cell.

[0110] When the second temperature acquisition unit is separated from fuel cell components, heat conduction is slow. When air is passed through the refrigerant, heat conduction is particularly slow when the cooling air flow rate is reduced. Therefore, by contacting the metal cooling fins, which have excellent thermal conductivity, the second temperature acquisition unit can quickly acquire the temperature of the cells surrounding the cooling fins.

[0111] The second temperature acquisition unit is electrically connected to the control unit, and the control unit detects the temperature of the fuel cell measured by the second temperature acquisition unit.

[0112] The second temperature acquisition unit can use a conventionally known temperature sensor, thermometer, or the like.

[0113] Because the heat capacity near the current collector plate located at the end of the fuel cell is large and its response to fuel cell temperature changes is delayed, the second temperature acquisition unit can be mounted so that it abuts against cooling fins located between two or more cells located inward from the end. The second temperature acquisition unit can also be inserted between the abutment areas of the cooling fins located between the cells and the ribs of the separator.

[0114] The second temperature acquisition unit may be mounted on the first spacer side or the second spacer side of the cooling fin.

[0115] Regarding the mounting position of the second temperature acquisition unit, if the gap between the cells is too narrow to allow the second temperature acquisition unit to be inserted, a protrusion protruding from the cell outer shape may be provided on the cooling fin and the second temperature acquisition unit may be mounted on the protrusion of the cooling fin.

[0116] A plurality of second temperature acquisition units may be provided. Providing a plurality of second temperature acquisition units can further improve temperature detection accuracy and can also detect local abnormalities in the fuel cell.

[0117] The second temperature acquisition unit may be provided near a position where the temperature of the fuel cell reaches the highest temperature.

[0118] The air-cooled fuel cell system includes an air introduction portion as an air system.

[0119] The air-cooled fuel cell system may further include an air intake portion that draws in air from outside the air-cooled fuel cell system.

[0120] The air introduction portion may be, for example, an air intake port or the like.

[0121] A pressure loss body may be provided in the air introduction portion. Examples of the pressure loss body include a filter and the like.

[0122] The air intake section may also include an air distribution section. The air distribution section distributes air introduced from the outside into reaction air and cooling air before it is introduced into the fuel cell. Furthermore, if the air intake section includes a reaction air intake section for introducing reaction air from the outside and a cooling air intake section for introducing cooling air from the outside, an air distribution section is not necessarily required.

[0123] The distribution ratio of the reaction air and the cooling air distributed by the air distribution part can be calculated as a flow ratio of 1:20 to 1:50.

[0124] The air distribution unit may be a housing capable of taking in air, etc. The material of the housing is not particularly limited, and may be metal, resin, carbon-based material, etc.

[0125] The fuel cell system includes a cooling system for the fuel cell.

[0126] The cooling system may include a cooling air supply flow path.

[0127] The cooling air supply flow path connects the air introduction portion to the cooling air inlet of the fuel cell. The cooling air inlet may also be a refrigerant supply hole, a cooling air inlet manifold, or the like.

[0128] The cooling system may include a cooling air exhaust flow path.

[0129] The cooling air discharge flow path connects the cooling air outlet of the fuel cell to the outside. The cooling air outlet may also be a refrigerant discharge hole, a cooling air outlet manifold, or the like.

[0130] The cooling air discharge flow path may include a refrigerant driving unit.

[0131] The refrigerant drive unit is electrically connected to the control unit. It is driven by a control signal from the control unit. The control unit controls the flow rate of refrigerant supplied from the refrigerant drive unit to the fuel cell. This also controls the temperature of the fuel cell.

[0132] Examples of the refrigerant driving unit include an air pump, an air compressor, a blower, and a fan.

[0133] The cooling system can reduce the pressure in the cooling air manifold of the fuel cell to below atmospheric pressure by providing a refrigerant driving unit on the outlet side of the cooling air.

[0134] The cooling system is valveless and open to the atmosphere, maintaining the cooling air at the same pressure as the outside air (e.g., -0.01 to -0.3 kPaG). This prevents differential pressure stress on the fuel cell structure and enables the use of inexpensive, lightweight housing components. Specifically, the cooling air supply and exhaust paths can also be piping.

[0135] The fuel cell system includes an oxidant gas system (reaction air system).

[0136] The oxidant gas system may also include a reaction air supply unit, a reaction air supply flow path, a reaction air exhaust flow path, a reaction air bypass flow path, a bypass valve, a reaction air flow sensor, etc. The reaction air supply flow path, the reaction air exhaust flow path, and the reaction air bypass flow path may specifically be pipes.

[0137] The reaction air supply unit supplies reaction air to the fuel cell. Specifically, the reaction air supply unit supplies reaction air to the cathode of the fuel cell.

[0138] The enclosed volume of the oxidant gas system may also be less than 5 times the enclosed volume of the fuel gas system.

[0139] Examples of the reaction air supply unit include an air pump, an air compressor, a hair dryer, and a blower fan.

[0140] The oxidant gas system includes an independent reaction air supply unit before introducing the reaction air into the fuel cell. By independently providing a refrigerant drive unit and reaction air supply unit in the cooling system and the oxidant gas system, the flow rates of the cooling and reaction air can be independently controlled. This allows for highly precise drainage and humidity control, improving the power generation performance of the fuel cell.

[0141] The reaction air supply unit is electrically connected to the control unit. The reaction air supply unit is driven according to a control signal from the control unit. The reaction air supply unit can also be controlled by the control unit to control at least one of the flow rate and pressure of the reaction air supplied from the reaction air supply unit to the cathode.

[0142] The reaction air supply flow path connects the reaction air supply unit and the reaction air inlet of the fuel cell.

[0143] The reaction air supply flow path enables the supply of reaction air from the reaction air supply unit to the cathode of the fuel cell. The reaction air inlet can also be an oxidant gas supply hole, a cathode inlet manifold, etc. The reaction air supply flow path can also branch from the air distribution unit.

[0144] The reaction air supply flow path includes a first valve in a region downstream of the reaction air supply portion and upstream of the reaction air inlet of the fuel cell.

[0145] The first valve may be directly disposed at the reaction air inlet of the fuel cell.

[0146] The first valve may be arranged upstream of the reaction air supply unit.

[0147] The first valve is electrically connected to the control unit, and when the first valve is opened by the control unit, reaction air is supplied from the reaction air supply flow path to the reaction air inlet of the fuel cell.

[0148] In the reaction air supply flow path, a pressure loss body may be provided upstream of the reaction air supply portion.

[0149] Examples of pressure loss elements include filters. A pressure loss element provided in the reaction air supply flow path may use a finer filter with a higher pressure loss than a pressure loss element provided in the air inlet. Cleaning the entire air inlet system increases the energy loss of the fuel cell. However, cleaning only the oxidant gas system can suppress the energy loss of the fuel cell. Furthermore, using a finer filter can reduce contamination of the cooling air, thereby improving the durability of the fuel cell.

[0150] The reaction air exhaust flow path connects the reaction air outlet of the fuel cell to the outside of the air-cooled fuel cell system. This flow path enables the exhaust of reaction air from the cathode of the fuel cell to the outside of the air-cooled fuel cell system. The reaction air outlet can also be an oxidant gas outlet hole, a cathode outlet manifold, or the like.

[0151] The reaction air exhaust flow path includes a second valve downstream of the reaction air outlet of the fuel cell. The second valve may be a sealing valve or an oxidant gas pressure regulating valve.

[0152] The second valve is electrically connected to the control unit, and the control unit opens the second valve to discharge the reaction air from the reaction air discharge flow path to the outside. In addition, the reaction air pressure (cathode pressure) supplied to the cathode can be adjusted by adjusting the opening of the second valve.

[0153] The reaction air bypass flow path branches off from the reaction air supply flow path, bypasses the fuel cell, and connects the branching portion of the reaction air supply flow path and the merging portion of the reaction air exhaust flow path.

[0154] A bypass valve is provided in the reaction air bypass flow path.

[0155] The bypass valve is electrically connected to the control unit. The control unit opens the bypass valve, allowing the reaction air to bypass the fuel cell and be discharged to the outside through the reaction air discharge passage when the reaction air supply to the fuel cell is not required. The first valve is a three-way valve, thus also serving as the bypass valve.

[0156] The reaction air flow rate sensor may be disposed in the reaction air supply flow path.

[0157] A reaction air flow sensor detects the flow rate of reaction air within the oxidant gas system. The reaction air flow sensor is electrically connected to the control unit. The control unit may also infer the rotational speed of the air compressor based on the flow rate of reaction air detected by the reaction air flow sensor. The reaction air flow sensor may also be positioned upstream of the reaction air supply unit in the reaction air supply flow path.

[0158] The reaction air flow sensor can be a conventionally known flow meter or the like.

[0159] In the oxidant gas system, the inlet-side reaction air supply unit and the second valve can form a pressure in the reaction air manifold of the fuel cell at a pressure higher than atmospheric pressure (eg, 5 to 15 kPaG).

[0160] The second valve of the oxidant gas system can increase the pressure of the reaction air, thereby increasing the oxygen partial pressure and preventing the fuel cell from drying out, thereby improving the performance of the fuel cell.

[0161] When the oxidant gas system and the cooling system are not separated, the pressure of the cooling air must be increased by about 30 times the flow rate of the reaction air, and the energy loss increases by 30 times or more.

[0162] The fuel cell system includes a fuel gas system.

[0163] The fuel gas system supplies fuel gas to the fuel cell.

[0164] The fuel gas system includes a fuel gas supply unit.

[0165] The fuel gas supply unit supplies fuel gas to the anode of the fuel cell.

[0166] Examples of the fuel gas supply unit include fuel tanks, and more specifically, liquid hydrogen tanks and compressed hydrogen tanks.

[0167] The fuel gas supply unit is electrically connected to the control unit and may be configured to control the opening and closing of a main stop valve of the fuel gas supply unit according to a control signal from the control unit, thereby controlling the on and off of the supply of fuel gas to the fuel cell.

[0168] The fuel gas system includes a fuel gas supply flow path. Specifically, the fuel gas supply flow path may be a pipe.

[0169] The fuel gas supply flow path connects the fuel gas supply unit to the fuel gas inlet of the fuel cell. The fuel gas supply flow path enables the supply of fuel gas to the anode of the fuel cell. The fuel gas inlet can also be a fuel gas supply hole, an anode inlet manifold, etc.

[0170] The fuel gas supply flow path includes a third valve upstream of the fuel gas inlet of the fuel cell.

[0171] The third valve may be directly disposed at the fuel gas inlet of the fuel cell.

[0172] The third valve may also be arranged upstream of the ejector.

[0173] The third valve is electrically connected to the control unit, and when the third valve is opened by the control unit, fuel gas is supplied from the fuel gas supply flow path to the fuel gas inlet of the fuel cell.

[0174] An ejector may be arranged in the fuel gas supply flow path.

[0175] The ejector can be placed at the junction of the fuel gas supply flow path and the circulation flow path. The ejector supplies a mixed gas containing fuel gas and circulating gas to the anode of the fuel cell. As the ejector, a conventionally known ejector can be used.

[0176] A pressure regulating valve and a medium-pressure hydrogen sensor may be disposed in a region between the fuel gas supply portion and the ejector in the fuel gas supply flow path.

[0177] The pressure regulating valve regulates the pressure of the fuel gas supplied from the fuel gas supply unit to the ejector.

[0178] The pressure regulating valve may be electrically connected to a control unit, and the opening and closing and opening degree of the pressure regulating valve may be controlled by the control unit to adjust the pressure of the fuel gas supplied to the ejector.

[0179] It can also be constructed as follows: the medium-pressure hydrogen sensor is electrically connected to the control unit, the control unit detects the pressure of the fuel gas measured by the medium-pressure hydrogen sensor, and controls the opening and closing and opening degree of the pressure regulating valve according to the detected pressure, thereby adjusting the pressure of the fuel gas supplied to the ejector.

[0180] The fuel gas system includes a fuel off-gas discharge flow path. Specifically, the fuel off-gas discharge flow path may be a pipe.

[0181] The fuel off-gas discharge flow path connects the fuel gas outlet of the fuel cell to the outside of the fuel cell system.

[0182] In the fuel off-gas discharge flow path, a gas-liquid separator may be disposed in a region between the fuel gas outlet and the outside of the fuel cell system.

[0183] The fuel off-gas discharge flow path may branch off from the circulation flow path via a gas-liquid separator.

[0184] The fuel off-gas discharge flow path discharges the fuel off-gas discharged from the fuel gas outlet of the fuel cell to the outside of the fuel cell system. The fuel gas outlet may also be a fuel gas discharge hole, an anode outlet manifold, or the like.

[0185] The fuel off-gas discharge flow path includes a fourth valve (fuel off-gas discharge valve, exhaust / drain valve) downstream of the fuel gas outlet of the fuel cell.

[0186] The fourth valve may be directly disposed at the fuel gas outlet of the fuel cell.

[0187] The fourth valve may be arranged in the fuel off-gas discharge flow path at a position downstream of the gas-liquid separator.

[0188] The fourth valve can discharge fuel off-gas, water, etc. to the outside (outside the system).

[0189] Furthermore, the outside may be the outside of the fuel cell system or the outside of the vehicle.

[0190] Alternatively, the fourth valve may be electrically connected to a control unit, and the opening and closing of the fourth valve may be controlled by the control unit to adjust the flow rate of fuel exhaust gas discharged to the outside and the flow rate of water (liquid water) discharged. Furthermore, the pressure of the fuel gas supplied to the anode of the fuel cell (anode pressure) may be adjusted by adjusting the opening of the fourth valve.

[0191] The fuel exhaust gas may also contain fuel gas that passes through the anode without reacting, and water generated at the cathode that reaches the anode. Fuel exhaust gas may also contain corrosive substances generated in the catalyst layer and electrolyte membrane, and oxidant gas that may be supplied to the anode during scavenging.

[0192] The fuel gas system may include a circulation flow path. Specifically, the circulation flow path may be a pipe.

[0193] The circulation flow path may also connect the fuel gas outlet of the fuel cell to the ejector.

[0194] The circulation flow path may be branched from the fuel off-gas discharge flow path and connected to an ejector disposed in the fuel gas supply flow path, thereby merging with the fuel gas supply flow path.

[0195] The circulation flow path may be branched from the fuel off-gas discharge flow path via a gas-liquid separator and connected to an ejector disposed in the fuel gas supply flow path, thereby merging with the fuel gas supply flow path.

[0196] The circulation flow path can recover the fuel off-gas, which is the fuel gas exhausted from the fuel gas outlet of the fuel cell, and supply it to the fuel cell as the circulation gas.

[0197] A gas circulation pump may be disposed in the circulation flow path. The gas circulation pump circulates the fuel exhaust gas as circulating gas. Alternatively, the gas circulation pump may be electrically connected to a control unit, and the control unit may control the on / off operation and rotational speed of the gas circulation pump to adjust the flow rate of the circulating gas.

[0198] A gas-liquid separator (anode gas-liquid separator) may be disposed in the circulation flow path.

[0199] The gas-liquid separator is arranged at a branch point between the fuel off-gas discharge flow path and the circulation flow path.

[0200] Therefore, the flow path from the fuel gas outlet to the gas-liquid separator may be a fuel off-gas discharge flow path or a circulation flow path.

[0201] The gas-liquid separator is arranged upstream of the fourth valve in the fuel off-gas discharge flow path.

[0202] The gas-liquid separator separates the fuel off-gas (fuel gas) discharged from the fuel gas outlet from water (liquid water). This allows the fuel off-gas to be returned to the circulation path as circulating gas, and allows the exhaust and drain valves in the fuel off-gas discharge path to be opened to discharge unnecessary gas and water. Furthermore, the gas-liquid separator prevents excess water from entering the circulation path, thereby preventing the circulation pump and other components from freezing due to this water.

[0203] The fuel cell system may also include a secondary battery.

[0204] The secondary battery (storage battery) can be any battery that can be charged and discharged. Examples of such batteries include nickel-metal hydride secondary batteries and lithium-ion secondary batteries. In addition, the secondary battery may also include an electric storage element such as a double-layer capacitor. The secondary battery may also be a structure in which a plurality of batteries are connected in series. The secondary battery supplies power to an electric motor, an air compressor, and the like. The secondary battery may also be charged from a power source external to the vehicle, for example. The secondary battery may also be charged by the output of a fuel cell. The charging and discharging of the secondary battery may also be controlled by a control unit.

[0205] The control unit physically includes, for example, a processing unit such as a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores control programs and control data processed by the CPU, a RAM (Random Access Memory) that is primarily used as a work area for various control processes, and a storage device such as an input / output interface. Alternatively, the control unit may be, for example, a control device such as an electronic control unit (ECU).

[0206] The control unit may also be electrically connected to an ignition switch, which may be mounted on a vehicle. Even if the ignition switch is turned off, the control unit may be operated by an external power supply.

[0207] The control unit monitors the temperatures acquired by the first temperature acquisition unit and the second temperature acquisition unit. The control unit may monitor the temperatures acquired by the first temperature acquisition unit and the second temperature acquisition unit during operation of the fuel cell.

[0208] When the difference between the temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature threshold, or when the difference between the temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature rise rate threshold, the control unit stops power generation of the fuel cell.

[0209] By observing the temperature difference or the temperature increase rate difference between the temperatures acquired by the first temperature acquisition unit and the second temperature acquisition unit, abnormality determination of the fuel cell can be performed.

[0210] During an abnormality, as the fuel cell temperature rises, the temperature difference ΔT12 between the temperature T1 acquired by the first temperature acquisition unit and the temperature T2 acquired by the second temperature acquisition unit increases rapidly. When ΔT12 reaches the abnormality determination threshold, an abnormality can be quickly determined. Using the temperature rise rate (the slope of the temperature curve) as a characteristic value for abnormality detection yields the same conclusion.

[0211] It can also be constructed as follows: when the difference between the temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is above a specified temperature threshold, or when the difference between the temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is above a specified temperature rise rate threshold, the control unit makes the openings of the first valve, the second valve, the third valve and the fourth valve smaller than the openings at the time of judgment.

[0212] The control unit may close the first valve, the second valve, the third valve, and the fourth valve when power generation of the fuel cell is stopped.

[0213] The predetermined temperature threshold value and the predetermined temperature rise rate threshold value may be appropriately set according to the performance and power generation state (heat generation) of the fuel cell.

[0214] Figure 1 This is an exploded perspective view showing an example of a portion of the fuel cell disclosed herein.

[0215] The fuel cell includes an assembly 18 having single cells 11 , cooling fins 15 , and gaskets 16 .

[0216] The cell 11 includes a first spacer 12 , a resin frame 14 for housing the MEGA in an opening, and a second spacer 13 in this order.

[0217] The cooling fins 15 are arranged on the surface of the second spacer 13 of the cell 11 in an area facing the MEGA, excluding the area where the gaskets 16 are arranged.

[0218] The gaskets 16 are arranged around the manifolds 17 on the surface of the second spacer 13 on the cooling fin 15 side.

[0219] The first isolating member 12, the resin frame 14 and the second isolating member 13 are provided with a manifold 17 through which reaction air as an oxidant gas or hydrogen as a fuel gas can flow as shown by the arrows, namely, an oxidant gas supply hole, an oxidant gas exhaust hole, a fuel gas supply hole and a fuel gas exhaust hole.

[0220] The cooling fins 15 are provided with a plurality of grooves serving as refrigerant flow paths through which cooling air serving as a refrigerant can flow as indicated by arrows.

[0221] The second temperature acquisition portion T2 is disposed at the downstream end portion of the cooling fin 15 in the flow direction of the cooling air.

[0222] Furthermore, the fuel cell may have a structure in which the refrigerant flows sideways.

[0223] Figure 2 This is a schematic cross-sectional view showing an example of a portion of the fuel cell disclosed herein.

[0224] like Figure 2 As shown, the cooling fins 15 are arranged between adjacent cells 11 .

[0225] The first temperature acquisition unit T1 is disposed upstream of the fuel cell in the flow direction of the cooling air of the cooling system 40 .

[0226] A plurality of second temperature acquisition portions T2 are arranged at the downstream end portion of the cooling fin 15 in the flow direction of the cooling air.

[0227] The second temperature acquisition portion T2 is arranged so as to abut against the cooling fins 15 arranged between two or more cells inward from the current collector plate 19 arranged at the end in the stacking direction of the fuel cell.

[0228] One of the plurality of second temperature acquisition portions T2 is inserted between the contact portions of the cooling fin 15 and the ribs of the spacer.

[0229] One of the plurality of second temperature acquisition units T2 is disposed at a protruding portion of a cooling fin 15 having a protruding portion that protrudes from an outer end portion of the fuel cell in the direction of the flow path of the cooling air.

[0230] The first temperature acquisition unit T1 and the second temperature acquisition unit T2 are electrically connected to the control unit 60 .

[0231] Figure 3 This is a schematic configuration diagram showing an example of an air-cooled fuel cell system of the present disclosure.

[0232] Figure 3 The illustrated air-cooled fuel cell system includes a fuel cell 10 , an air system 20 , an oxidant gas system 30 , a cooling system 40 , a fuel gas system 50 , a control unit 60 , a first temperature acquisition unit T1 , and a second temperature acquisition unit T2 .

[0233] The air system 20 includes an air intake portion 21 having a filter and an air distribution portion.

[0234] The air taken in by the air introduction unit 21 is distributed to the oxidant gas system 30 and the cooling system 40 by the air distribution unit.

[0235] The oxidizing gas system 30 includes a filter 31 , a reaction air supply unit 32 , a reaction air supply flow path 33 , a reaction air exhaust flow path 34 , a first valve 35 , and a second valve 36 .

[0236] In the reaction air supply flow path 33 , a filter 31 , a reaction air supply unit 32 , and a first valve 35 are arranged along the flow direction of air.

[0237] A second valve 36 is provided in the reaction air exhaust flow path 34 .

[0238] The cooling system 40 includes a cooling air supply flow path 41 , a cooling air discharge flow path 42 , and a refrigerant driving unit 43 .

[0239] The fuel gas system 50 includes a fuel gas supply unit 51 , a fuel gas supply flow path 52 , a fuel off-gas discharge flow path 53 , a circulation flow path 54 , a gas-liquid separator 55 , a gas circulation pump 56 , a third valve (ejector, etc.) 57 , and a fourth valve (exhaust valve, etc.) 58 .

[0240] The first temperature acquisition unit T1 is disposed in the cooling air supply flow path 41 and measures the temperature of the inflowing cooling air.

[0241] The first temperature acquisition unit T1 is electrically connected to the control unit 60 , and the control unit 60 detects the temperature of the inflowing cooling air measured by the first temperature acquisition unit T1 .

[0242] The second temperature acquisition unit T2 is disposed on the fuel cell 10 so as to contact the cooling fins, and measures the temperature of the fuel cell 10 .

[0243] The second temperature acquisition unit T2 acquires the temperature of the fuel cell 10 , and the control unit 60 detects the temperature of the fuel cell 10 acquired by the second temperature acquisition unit T2 .

[0244] Figure 4 1 is a schematic structural diagram showing another example of the air-cooled fuel cell system disclosed in the present invention. Figure 4 Middle pair and Figure 3 The same configuration is denoted by the same reference numerals, and description thereof will be omitted.

[0245] exist Figure 4 In the air-cooled fuel cell system, the air system 20 includes a reaction air inlet 22 for supplying air to the oxidant gas system 30 and a cooling air inlet 23 for supplying air to the cooling system 40 .

[0246] The reaction air introduction part 22 and the cooling air introduction part 23 each include a filter.

[0247] The oxidant gas system 30 and the cooling system 40 respectively obtain air from the atmosphere through filters.

[0248] The oxidizing gas system 30 includes a filter 31 , a reaction air supply unit 32 , a reaction air supply flow path 33 , a reaction air exhaust flow path 34 , a first valve 35 , a second valve 36 , and a reaction air bypass flow path 37 .

[0249] A filter 31, a reaction air supply unit 32, and a first valve 35 are arranged along the air flow direction in the reaction air supply flow path 33. The first valve 35 is a three-way valve that allows reaction air to flow from the reaction air bypass flow path 37 to the reaction air exhaust flow path 34, bypassing the fuel cell 10.

[0250] A second valve 36 is provided in the reaction air exhaust flow path 34 .

[0251] The fuel gas system 50 includes a fuel gas supply unit 51 , a fuel gas supply flow path 52 , a fuel off-gas discharge flow path 53 , a circulation flow path 54 , a gas-liquid separator 55 , a third valve (ejector, etc.) 57 , a fourth valve (exhaust valve, etc.) 58 , and an ejector 59 .

[0252] The plurality of second temperature acquisition units T2 are arranged in the fuel cell 10 so as to contact the cooling fins.

[0253] Figure 5 This is a flowchart showing an example of control of the air-cooled fuel cell system of the present disclosure.

[0254] The control unit monitors the temperatures acquired by the first temperature acquisition unit and the second temperature acquisition unit during operation of the fuel cell.

[0255] The control unit determines whether the difference between the temperatures acquired by the first temperature acquisition unit and the second temperature acquisition unit is greater than a predetermined temperature threshold, or whether the difference between the temperature increase rates acquired by the first temperature acquisition unit and the second temperature acquisition unit is greater than a predetermined temperature increase rate threshold.

[0256] When the difference between the temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a predetermined temperature threshold, or when the difference between the temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a predetermined temperature rise threshold, the control unit makes the openings of the first valve, the second valve, the third valve, and the fourth valve smaller than the openings at the time of determination, or stops power generation by the fuel cell. The control unit may also close the first valve, the second valve, the third valve, and the fourth valve when power generation by the fuel cell is stopped. On the other hand, when the difference between the temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is less than a predetermined temperature threshold, or when the difference between the temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is less than a predetermined temperature rise threshold, the control unit may terminate control or maintain the status quo.

[0257] If excessive temperature rise is observed, the valve of the reaction air system may be sealed. This reduces the fuel cell voltage due to oxygen deficiency, allowing the fuel cell to safely stop power generation.

[0258] Furthermore, degradation of the fuel cell can be suppressed. Even if a fire occurs in the fuel cell, the spread of the fire can be prevented by cutting off oxygen.

[0259] By making the number of moles of hydrogen in the sealed fuel gas system greater than twice the number of moles of oxygen in the sealed reaction air system, oxygen within the fuel cell system is consumed, causing the fuel cell voltage to drop. Furthermore, since the fuel cell is sealed while it is rich in hydrogen, degradation of the fuel cell can be slowed. To completely consume oxygen, the reaction air system can be sealed while continuing to supply fuel gas for a specified period of time, and then the fuel gas system can be sealed after oxygen consumption reaches a certain level. Alternatively, the first and second valves can be closed, and then the third and fourth valves can be closed after a specified period of time.

Claims

1. An air-cooled fuel cell system, characterized in that: The air-cooled fuel cell system comprises: fuel cells; a first temperature acquisition unit; a second temperature acquisition unit; and Control Department, The fuel cell has metal cooling fins. The first temperature acquisition unit is arranged near the cooling air inlet of the fuel cell and at a position separated from the cooling fins. The second temperature acquisition unit is arranged so as to abut against the cooling fin. The control unit monitors the temperatures acquired by the first temperature acquisition unit and the second temperature acquisition unit, When the difference between the temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature threshold, or when the difference between the temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature rise rate threshold, the control unit stops power generation of the fuel cell.

2. The air-cooled fuel cell system according to claim 1, characterized in that: The air-cooled fuel cell system further comprises: an air inlet portion for introducing air from outside the air-cooled fuel cell system; a reaction air supply unit for supplying the reaction air to the fuel cell; a reaction air supply flow path connecting the reaction air supply portion to the reaction air inlet of the fuel cell; a reaction air exhaust passage connecting the reaction air outlet of the fuel cell to the outside; a cooling air supply flow path connecting the air introduction portion to the cooling air inlet of the fuel cell; a fuel gas supply unit for supplying fuel gas to the fuel cell; a fuel gas supply flow path connecting the fuel gas supply portion to a fuel gas inlet of the fuel cell; and The fuel exhaust gas discharge flow path connects the fuel gas outlet of the fuel cell to the outside. The fuel cell has a structure in which the reaction air manifold and the cooling air manifold are independent. The reaction air supply flow path includes a first valve in a region downstream of the reaction air supply portion and upstream of the reaction air inlet of the fuel cell. The reaction air exhaust flow path includes a second valve downstream of the reaction air outlet of the fuel cell. The fuel gas supply flow path includes a third valve upstream of the fuel gas inlet of the fuel cell. The fuel off-gas discharge flow path includes a fourth valve downstream of the fuel gas outlet of the fuel cell. When the difference between the temperatures obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature threshold, or when the difference between the temperature rise rates obtained by the first temperature acquisition unit and the second temperature acquisition unit is greater than a specified temperature rise rate threshold, the control unit reduces the openings of the first valve, the second valve, the third valve, and the fourth valve.

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