WO2011089502A1 - Système de piles à combustibles et son procédé de commande - Google Patents

Système de piles à combustibles et son procédé de commande Download PDF

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Publication number
WO2011089502A1
WO2011089502A1 PCT/IB2011/000066 IB2011000066W WO2011089502A1 WO 2011089502 A1 WO2011089502 A1 WO 2011089502A1 IB 2011000066 W IB2011000066 W IB 2011000066W WO 2011089502 A1 WO2011089502 A1 WO 2011089502A1
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WIPO (PCT)
Prior art keywords
pressure
cathode
fuel cell
reaction gas
cathode layer
Prior art date
Application number
PCT/IB2011/000066
Other languages
English (en)
Inventor
Manabu Kato
Kazutaka Kimura
Hideyuki Kumei
Michihito Tanaka
Shuya Kawahara
Tsuyoshi Maruo
Kazuhiko Kohari
Original Assignee
Toyota Jidosha Kabushiki Kaisha
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Application filed by Toyota Jidosha Kabushiki Kaisha filed Critical Toyota Jidosha Kabushiki Kaisha
Publication of WO2011089502A1 publication Critical patent/WO2011089502A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04104—Regulation of differential pressures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04007—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids related to heat exchange
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04197—Preventing means for fuel crossover
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0432—Temperature; Ambient temperature
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0438—Pressure; Ambient pressure; Flow
    • H01M8/04395—Pressure; Ambient pressure; Flow of cathode reactants at the inlet or inside the fuel cell
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0438—Pressure; Ambient pressure; Flow
    • H01M8/04402—Pressure; Ambient pressure; Flow of anode exhausts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0438—Pressure; Ambient pressure; Flow
    • H01M8/0441—Pressure; Ambient pressure; Flow of cathode exhausts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/0438—Pressure; Ambient pressure; Flow
    • H01M8/04432—Pressure differences, e.g. between anode and cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/04664—Failure or abnormal function
    • H01M8/04679—Failure or abnormal function of fuel cell stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04753—Pressure; Flow of fuel cell reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04761—Pressure; Flow of fuel cell exhausts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04776—Pressure; Flow at auxiliary devices, e.g. reformer, compressor, burner
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04694—Processes for controlling fuel cells or fuel cell systems characterised by variables to be controlled
    • H01M8/04746—Pressure; Flow
    • H01M8/04783—Pressure differences, e.g. between anode and cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1007—Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M2008/1095—Fuel cells with polymeric electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention relates to a fuel cell.
  • JP-A-2004- 179054 suggests a system that resupplies hydrogen gas to the anode after a stop of power generation of the fuel cell. Note that a portion deficient in hydrogen gas partially arises in the anode layer through the above described reaction. In this case, an abnormal potential occurs in the cathode catalyst layer corresponding to the hydrogen gas-deficient portion, so degradation (carbon oxidation) of the cathode catalyst layer can occur.
  • anode-side residual hydrogen gas permeates to the cathode.
  • Hydrogen gas that permeates to the cathode reacts with oxygen in the cathode-side residual air to produce water.
  • the oxygen partial pressure in the cathode decreases, so the total pressure in the cathode decreases and can be lower than an atmospheric pressure (become a negative pressure).
  • the invention provides a fuel cell system and a control method therefor, which prevent a cathode from becoming a negative pressure after a stop of power generation of a fuel cell.
  • a first aspect of me invention relates to a fuel cell system.
  • the fuel cell system includes: a fuel cell that includes a fuel cell that includes an electrolyte membrane, a cathode layer that is in contact with the electrolyte membrane and that supplies cathode reaction gas, containing oxygen, to the electrolyte membrane, and an anode layer that is in contact with the electrolyte membrane on an opposite side of the electrolyte membrane to a side of the electrolyte membrane on which the cathode layer is provided and that supplies anode reaction gas to the electrolyte membrane; and a pressure regulating device that, after a stop of power generation of the fuel cell, regulates a total pressure in the cathode layer so that a total partial pressure that is a total of partial pressures of gases, other than an oxygen partial pressure, in the cathode layer is higher than or equal to an atmospheric pressure.
  • the total pressure in the cathode layer is regulated so that the total partial pressure that is the total of the partial pressures of gases, other than the oxygen partial pressure, in the cathode layer is higher than or equal to the atmospheric pressure. Therefore, even when residual oxygen is consumed by the reaction between hydrogen gas that migrates from the anode layer to the cathode layer via the electrolyte membrane and oxygen remaining in the cathode layer and, as a result, the oxygen partial pressure in the cathode layer decreases, it is possible to prevent the total pressure in the cathode layer from becoming a negative pressure (lower than the atmospheric pressure).
  • the pressure regulating device may include a cathode reaction gas supply passage for supplying the cathode reaction gas to the fuel cell, a cathode reaction gas exhaust passage for exhausting the cathode reaction gas from the cathode layer, a supply-side shut-off valve that is arranged in the cathode reaction gas supply passage and that is able to shut off the cathode reaction gas supply passage, an exhaust-side shut-off valve that is arranged in the cathode reaction gas exhaust passage and that is able to shut off the cathode reaction gas exhaust passage, a valve control unit that controls the supply-side shut-off valve and the exhaust-side shut-off valve, and a reaction gas supply portion that supplies the cathode reaction gas to the fuel cell via the cathode reaction gas supply passage, and the pressure regulating device may, after a stop of power generation of the fuel cell, control the valve control unit to shut off the cathode reaction gas exhaust passage using the exhaust
  • the cathode reaction gas supply passage and the cathode reaction gas exhaust passage are shut off after the total pressure in the cathode layer is regulated, so the total pressure in the cathode layer does not need to be continuously regulated.
  • the process executed by the pressure regulating device may be configured to be simple, and running cost required to drive the pressure regulating device may be reduced.
  • the phrase "shut off' in the above aspect not only includes a hermetically sealed state but also includes a state where flow of the cathode reaction gas is suppressed.
  • the target pressure may be set so that a difference in pressure between the cathode layer and the anode layer is lower than a predetermined threshold.
  • the pressure regulating device may regulate the total pressure in the cathode layer so that an average of the total partial pressure and a total pressure in the anode layer is higher than or equal to the atmospheric pressure.
  • the pressure regulating device may include a saturated water vapor pressure estimating unit that estimates a post-standing saturated water vapor pressure, which is a saturated water vapor pressure in the cathode layer after a lapse of a predetermined period of time from a stop of power generation of the fuel cell, on the basis of a temperature relevant to the fuel cell, and a target pressure setting unit that sets a target pressure that is targeted when the pressure regulating device regulates the total pressure in the cathode layer in accordance with the post-standing saturated water vapor pressure, and the pressure regulating device may regulate the total pressure in the cathode layer so as to coincide with the target pressure.
  • a saturated water vapor pressure estimating unit that estimates a post-standing saturated water vapor pressure, which is a saturated water vapor pressure in the cathode layer after a lapse of a predetermined period of time from a stop of power generation of the fuel cell, on the basis of a temperature relevant to the fuel cell
  • a target pressure setting unit that sets a target pressure that is targeted
  • the fuel cell system may further include: a pressure variation rate acquisition unit that acquires a rate of variation in the total pressure in the cathode layer when the pressure regulating device regulates the total pressure in the cathode layer; and a degradation determining unit that determines a degree of degradation of the fuel cell on the basis of the acquired rate of variation.
  • the degree of degradation of the fuel cell it is possible to simply determine the degree of degradation of the fuel cell.
  • the degree of degradation of the fuel cell may be deteimined to be larger as the rate of variation in the total pressure in the cathode layer decreases.
  • the fuel cell system according to the first aspect may further include a bypass flow passage that is arranged in the cathode layer and that circulates the cathode reaction gas.
  • a second aspect of the invention relates to a control method for a fuel cell system that includes a fuel cell having an electrolyte membrane and a cathode layer that is in contact with the electrolyte membrane and that supplies cathode reaction gas, containing oxygen, to the electrolyte membrane.
  • the control method includes: after a stop of power generation of the fuel cell, regulating a total pressure in the cathode layer so that a total partial pressure that is a total of partial pressures of gases, other than an oxygen partial pressure, in the cathode layer is higher than or equal to an atmospheric pressure.
  • the total pressure in the cathode layer is regulated so that the total partial pressure that is the total of the partial pressures of gases, other than the oxygen partial pressure, in the cathode layer is higher than or equal to the atmospheric pressure. Therefore, even when residual oxygen is consumed by the reaction between hydrogen gas that migrates from the anode layer to the cathode layer via the electrolyte membrane and oxygen remaining in the cathode layer and, as a result, the oxygen partial pressure in the cathode layer decreases, it is possible to prevent the total pressure in the cathode layer from becoming a negative pressure (lower than the atmospheric pressure).
  • a cathode reaction gas exhaust passage for exhausting the cathode reaction gas from the cathode layer may be shut off, in a state where the cathode reaction gas exhaust passage is shut off, the total pressure in the cathode layer at which the total partial pressure that is the total of the partial pressures of gases, other than the oxygen partial pressure, in the cathode layer is higher than or equal to the atmospheric pressure, as a target pressure for regulating the total pressure in the cathode layer, is calculated, the cathode reaction gas may be supplied to the fuel cell via a cathode reaction gas supply passage for supplying the cathode reaction gas to the fuel cell to regulate the total pressure in the cathode layer so as to achieve the target pressure, and, in a state where the total pressure in the cathode layer is regulated so as to achieve the target pressure, the cathode reaction gas supply passage may be shut off.
  • the cathode reaction gas supply passage and the cathode reaction gas exhaust passage are shut off after the total pressure in the cathode layer is regulated, so the total pressure in the cathode layer does not need to be continuously regulated.
  • the process in connection with the fuel cell system may be configured to be simple, and running cost required to execute the process may be reduced.
  • the phrase "shut off' in the above aspect not only includes a hermetically sealed state but also includes a state where floW of the cathode reaction gas is suppressed.
  • FIG 1 is a view that illustrates the schematic configuration of a fuel cell system according to a first embodiment of the invention
  • FIG 2 is a first sectional view that schematically shows the detailed configuration of each single cell shown in FIG 1 ;
  • FIG. 3 is a second sectional view that schematically shows the detailed configuration of each single cell shown in FIG 1 ;
  • FIG 4 is a flowchart that shows the procedure of pressure regulating process executed after a stop of power generation of a fuel cell stack according to the first embodiment of the invention
  • FIG. 5 is a graph that schematically illustrates a target pressure set in step SI 5 in FIG. 4;
  • FIG. 6 is a graph that illustrates a variation in cathode pressure in a comparative embodiment
  • FIG. 7 is a view that illustrates the schematic- configuration of a fuel cell system ac(x rding to a second embodiment of the invention.
  • FIG. 8 is a flowchart that shows the procedure of pressure regulating process according to the second embodiment of the invention.
  • FIG 9 is a graph that schematically illustrates the details set in a target pressure map according to the second embodiment of the invention.
  • FIG 10 is a view that schematically illustrates a method of determining a target pressure according to a third embodiment of the invention.
  • FIG 11 is a view that illustrates the schematic configuration of a fuel cell system according to a third alternative embodiment of the invention.
  • FIG 1 is a view that illustrates the schematic configuration of a fuel cell system according to a first embodiment of the invention.
  • the fuel cell system 100 is equipped for an electric vehicle as a system for supplying driving power.
  • the fuel cell system 100 includes a fuel cell stack 1Q > an air compressor 30, a hydrogen tank 40, a shut-off valve 63, an anode gas supply pressure regulating valve 64, a cathode gas supply flow passage 51 , a cathode gas exhaust flow passage 52, an anode gas supply flow passage 53, an anode gas exhaust flow passage 54, a cathode back pressure regulating valve 61, an anode back pressure regulating valve 62, first to fourth pressure sensors 71 to 74 and a control unit 90.
  • the fuel cell stack 10 is formed so that a plurality of single cells 11, each of which is a polymer electrolyte fuel cell that has an excellent power generation efficiency with a relatively small size, are stacked. Electrochemical reaction occurs between pure hydrogen (anode gas) and oxygen (cathode gas) in air at each electrode to generate electromotive force.
  • the air compressor 30 is arranged in the cathode gas supply flow passage 51.
  • the air compressor 30 pressurizes air taken in from the outside and then supplies the pressurized air to the fuel cell stack 10. Note that, when the air compressor 30 is stopped, flow of cathode gas in the cathode gas supply flow passage 51 is suppressed. That is, the cathode gas supply flow passage 51 is shut off by the air compressor 30.
  • the hydrogen tank 40 stores high-pressure hydrogen gas.
  • the hydrogen tank 40 may be, for example, a tank that includes a hydrogen storage alloy inside and that causes the hydrogen storage alloy to occlude hydrogen to store hydrogen.
  • the shut-off valve 63 is arranged at a hydrogen gas outlet (not shown) of the hydrogen tank 40.
  • the shut-off valve 63 supplies hydrogen gas or stops supply of hydrogen gas.
  • the anode gas supply pressure regulating valve 64 is arranged in the anode gas supply flow passage 53.
  • the anode gas supply pressure regulating valve 64 decreases the pressure of high-pressure hydrogen gas, discharged from the hydrogen tank 40, to a predetermined pressure.
  • the cathode gas supply flow passage 51 provides fluid communication between the air compressor 30 and the fuel cell stack 10.
  • the cathode gas supply flow passage 51 is used to guide compressed air, supplied from the air compressor 30, to the fuel cell stack 10.
  • the cathode gas exhaust flow passage 52 is used to exhaust redundant air (cathode off-gas) and produced water, exhausted from the fuel cell stack 10, to the outside.
  • the anode gas supply flow passage 53 provides fluid communication between the hydrogen tank 40 and the fuel cell stack 10.
  • the anode gas supply flow passage 53 is used to guide hydrogen gas, supplied from the hydrogen tank 40, to the fuel cell stack 10.
  • the anode gas exhaust flow passage 54 is used to exhaust redundant hydrogen gas (anode off-gas), exhausted from the fuel cell stack 10, to the outside. Note that it is also applicable that a flow passage (circulating flow passage) that is connected to the anode gas supply flow passage 53 is provided for the anode gas exhaust flow passage 54 and then redundant hydrogen gas is supplied again to the fuel cell stack 10 via the circulating flow passage.
  • the cathode back pressure regulating valve 1 is arranged in the cathode gas exhaust flow passage 52.
  • the cathode back pressure regulating valve 61 operates so as to keep the cathode pressure (back pressure) of the fuel cell stack 10 constant.
  • the anode back pressure regulating valve 62 is arranged in the anode gas exhaust flow passage 54.
  • the anode back pressure regulating valve 62 operates so as to keep the anode pressure (back pressure) of the fuel cell stack 10 constant.
  • Each of the above described valves 61 to 64 is an electromagnetic valve. Note that the valves 61 to 64 are able to shut off the corresponding flow passages in which the valves 61 to 64 are arranged in such a manner that the opening degrees of the valves 61 to 64 are set at zero.
  • a first pressure sensor 71 is arranged in the cathode gas supply flow passage 51.
  • the first pressure sensor 71 measures the internal pressure of the cathode gas supply flow passage 51.
  • a second pressure sensor 72 is arranged in the cathode gas exhaust flow passage 52.
  • the second pressure sensor 72 measures the cathode pressure (back pressure) of the fuel cell stack 10.
  • a third pressure sensor 73 is arranged in the anode gas exhaust flow passage 54.
  • the third pressure sensor 73 measures the anode pressure (back pressure) of the fuel cell stack 10.
  • a fourth pressure sensor 74 is arranged at a location remote from the fuel cell stack 10.
  • the fourth pressure sensor 74 measures the atmospheric pressure. Note that the fourth pressure sensor 74 may be arranged so as to be in contact with the fuel cell stack 10 or the flow, passages 51 to 54.
  • the control unit 90 is electrically connected to the air compressor 30 and the valves 61 to 64.
  • the control unit 90 controls these elements.
  • the control unit 90 is connected to the pressure sensors 71 to 74.
  • the control unit 90 acquires pressure values measured respectively by the pressure sensors 71 to 74.
  • the control unit 90 includes a central processing unit (CPU) 91, a read only memory (ROM) 92 and a random access memory (RAM) 93.
  • the ROM 92 stores a control program (not shown) for controlling the fuel cell system 100.
  • the CPU 91 executes the control program using the RAM 93 to function as a pressure regulating unit 91 and a valve control unit 91 b.
  • the valve control unit 91b regulates the opening degree of each of the valves 61 to 64 to control the flow rate of reaction gas (air or hydrogen gas) that flows through a corresponding one of the flow passages 51 to 54.
  • the pressure regulating unit 91a controls the rotational speed of the air compressor 30 and also controls the valves 61 to 64 via the valve control unit 91b to thereby regulate the pressure in the cathode layer (the cathode catalyst layer and the cathode gas diffusion layer) in each single cell 11.
  • FIG 2 is a first sectional view that schematically shows the detailed configuration of each single cell shown in FIG 1.
  • FIG. 3 is a second sectional view that schematically shows the detailed configuration of each single cell shown in FIG 1.
  • FIG 2 shows a state of each single cell 1 1 during power generation.
  • FIG 3 shows a state of each single cell after a stop of power generation. Note that FIG 2 shows flow of cathode gas (air) during power generation by the solid arrow together with the detailed configuration of each single cell.
  • each single cell 11 is formed so that a membrane electrode and gas diffusion layer assembly (MEGA) 111 and a separator 121 are superposed on top of each other.
  • the MEGA 11 1 includes an electrolyte membrane 112, a cathode layer 114 and an anode layer 113.
  • the electrolyte membrane 112 is an ion exchange membrane made of a fluororesin containing a sulfonic acid group.
  • the electrolyte membrane 112 may be, for example, Nafion (trademark) produced by Du Pont, Aciplex (trademark) produced by Asahi Kasei Corporation, or the like.
  • the electrolyte membrane 112 may be a hydrocarbon sulfonic acid group membrane.
  • the cathode layer 114 is arranged so as to be in contact with one of surfaces of the electrolyte membrane 112.
  • the cathode layer 114 includes a catalyst layer (not shown) and a gas difiusion layer (not shown).
  • the cathode layer 114 is formed of a material that has gas permeability and high conductivity.
  • the catalyst layer may be, for example, formed in such a manner that slurry that is prepared by mixing catalyst-supported particles (platinum-supported , carbon, or the like), a polymer electrolyte and a water repellent material is applied to the electrolyte membrane.
  • the gas dififusion layer may be formed of a porous member (for example, carbon paper, carbon cloth or vitreous carbon).
  • the anode layer 113 is arranged so as to be in contact with a surface of the electrolyte membrane 112, which is opposite to the surface on which the cathode layer 114 is arranged.
  • the anode layer 113 includes a catalyst layer (not shown) and a gas diffusion layer (not shown). Note that the confLguration of the anode layer 113 is similar to that of the cathode layer 114, so the description thereof is omitted.
  • Each separator 121 may be formed of a gas-impermeable conductive member, such as a dense carbon formed by compressing carbon to be gas impermeable and a metal plate formed by pressing. Note that each separator 121 has grooves (not shown) on its surfaces that contact the adjacent MEGAs 111, and, when each separator 121 is connected to the adjacent MEGAs 111, reaction gas (air or hydrogen gas) flow passages are formed at boundary portions between the separator 121 and the adjacent MEGAs 111.
  • a gas-impermeable conductive member such as a dense carbon formed by compressing carbon to be gas impermeable and a metal plate formed by pressing. Note that each separator 121 has grooves (not shown) on its surfaces that contact the adjacent MEGAs 111, and, when each separator 121 is connected to the adjacent MEGAs 111, reaction gas (air or hydrogen gas) flow passages are formed at boundary portions between the separator 121 and the adjacent MEGAs 111.
  • the MEGAs 111 and the separators 121 respectively have through holes in their thickness directions.
  • a cathode gas supply manifold 511, a cathode gas exhaust manifold 521, an anode gas supply manifold (not shown) and an anode gas exhaust manifold (not shown) are formed in the fuel cell stack 10.
  • the cathode gas supply manifold 511 is connected to the cathode gas supply flow passage 51 shown in FIG 1.
  • the cathode gas exhaust manifold 521 is connected to the cathode gas exhaust flow passage 52 shown in FIG 1.
  • air supplied through the cathode gas supply manifold 511 is supplied to the cathode layers 114 via flow passages (not shown) formed at boundary portions between the separators 121 and the adjacent cathode layers 114.
  • supplied air is diffused and used for electrochemical reaction.
  • Redundant air that is not used for electrochemical reaction is exhausted to the cathode gas exhaust manifold 521 via flow passages (not shown) formed at boundary portions between the separators 121 and the adjacent cathode layers 114.
  • the above described air compressor 30, pressure regulating unit 91 a, valve control unit 91b, cathode gas supply flow passage 51, cathode gas exhaust flow passage 52 and cathode back pressure regulating valve 61 correspond to a pressure regulating device according to the aspects of the invention.
  • the air compressor 30 corresponds to a supply-side shut-off valve and a reaction gas supply portion according to the aspects of the invention
  • the pressure regulating unit 91a corresponds to a saturated water vapor pressure estimating unit and a target pressure setting unit according to the aspects of the invention.
  • FIG 4 is a flowchart that shows the procedure of pressure regulating process executed after a stop of power generation of the fuel cell stack 10.
  • the pressure regulating process is started. Note that, during a stop of power generation of the fuel cell stack 10, the shut-off valve 63 is closed, and the air compressor 30 is stopped.
  • the pressure regulating unit 91a acquires the atmospheric pressure from a measured value transmitted from the fourth pressure sensor 74 (step S10).
  • the atmospheric pressure measured by the fourth pressure sensor 74 varies depending on an environment in which the fuel cell system 100 is installed. For example, the atmospheric pressure is relatively low when the electric vehicle is located at high altitudes; whereas the atmospheric pressure is relatively high when the electric vehicle is located at low altitudes.
  • the pressure regulating unit 91a obtains a pressure at which the total of partial pressures of gases, other than the oxygen partial pressure, coincides with the atmospheric pressure, and sets the obtained pressure as a target pressure (step S I 5).
  • a target pressure As will be described later, after a stop of power generation, air is supplied again to the cathodes of the fuel cell stack 10, and the pressure in each cathode layer 114 is increased.
  • the "target pressure" in step S15 means a final target pressure to which the pressure in each cathode layer 114 is increased.
  • FIG. 5 is a graph that schematically illustrates the target pressure set in step SI 5 of FIG. 4.
  • the ordinate axis represents the pressure in each cathode layer 114 (hereinafter, referred to as "cathode pressure").
  • the left bar indicates a cathode pressure immediately after the pressure regulating process is executed
  • the right bar indicates a cathode pressure after a lapse of a long period of time from when the pressure regulating process is executed.
  • Air contains about 21% of oxygen and 79% of the other gases, such as nitrogen, carbon dioxide and water vapor.
  • the target pressure Pt is derived as a pressure at which the total partial pressure (Ptx0.79) of gases, other than the partial pressure (Ptx0.21) of oxygen, coincides with the atmospheric pressure (Pa).
  • valve control unit 91b sets the opening degree of the cathode back pressure regulating valve 61 at zero to shut off the cathode gas exhaust flow passage 52 (step S20).
  • the pressure regulating unit 91a drives the air compressor 30 to supply air to the cathodes of the fuel cell stack 10 (step S25). Because the cathode gas exhaust flow passage 52 is shut off in step S20, the cathode pressure gradually increases through step S25.
  • the pressure regulating unit 91a waits until the cathode pressure reaches the target pressure on the basis of a measured value of the second pressure sensor 72 (step S30).
  • the measured value of the second pressure sensor 72 is used as an actually measured cathode pressure.
  • a measured value of the first pressure sensor 71 or a value (average value, or the like) calculated from the measured values of the two pressure sensors 71 and 72 may be used as an actually measured cathode pressure.
  • the pressure regulating unit 91a stops the air compressor 30, and the valve control unit 91b shuts off the cathode gas supply flow passage 51 (step S35).
  • step S35 flow of cathode gas is suppressed in the cathode gas supply flow passage 51, and, in addition, the cathode gas exhaust flow passage 52 is shut off, so the cathode pressure is maintained at the target pressure for a while.
  • hydrogen gas that migrates from the anode layers 113 to the cathode layers 114 consumes oxygen in residual air in the cathode layers 114 as shown in FIG. 3, so the cathode pressure (total pressure) decreases as shown in FIG. 5.
  • the target pressure Pt (that is, the pressure immediately after the pressure regulating process) is the pressure at which the total partial pressure of gases, other than the partial pressure of oxygen, coincides with the atmospheric pressure, the total partial pressure of gases also coincides with the atmospheric pressure even when the oxygen partial pressure becomes zero as shown in FIG 5. This prevents the cathode pressure from becoming a negative pressure.
  • FIG 6 is a graph that illustrates a variation in cathode pressure in a comparative embodiment
  • the ordinate axis of FIG 6 represents the pressure in each cathode layer as in the case of FIG 5.
  • the left bar indicates a cathode pressure (total pressure) immediately after a stop of power generation
  • the right bar indicates a cathode pressure after a lapse of a long period of time from when power generation is stopped.
  • the cathode pressure is the atmospheric pressure (Pa).
  • Pa the atmospheric pressure
  • the cathode layer does not become a negative pressure.
  • the pressure regulating process is executed to regulate the total pressure in each cathode layer 114 so that the total partial pressures of gases, other than the oxygen partial pressure, in each cathode layer 114 is higher than or equal to the atmospheric pressure, so it is possible to prevent each cathode layer 1 4 from becoming a negative pressure after a lapse of a long period of time from when power generation of the fuel cell stack 10 is stopped.
  • This prevents air from being drawn from the cathode gas supply manifold 511 and the cathode gas exhaust manifold 521 into each cathode layer 114.
  • flow of residual air into each anode layer 113 is suppressed, so adsorption of oxygen to the catalyst material of the anode catalyst layer and degradation (carbon oxidation) of the cathode catalyst layer are suppressed.
  • the cathode gas exhaust flow passage 52 is shut off and then the air compressor 30 is driven to increase the cathode pressure, and, after that, the air compressor 30 is stopped to suppress flow of cathode gas through the cathode gas supply flow passage 51.
  • the air compressor 30 does not need to be continuously driven in order to keep the total pressure in each cathode layer 114 higher than or equal to the atmospheric pressure, so it is possible to reduce riinning cost required to drive the air compressor 30.
  • FIG 7 is a view that illustrates the schematic configuration of a fuel cell system according to a second embodiment.
  • FIG. 8 is a flowchart that shows the procedure of pressure regulating process according to the second embodiment.
  • the fuel cell system 100a according to the second embodiment as shown in FIG 7 differs from the fuel cell system 100 according to the first embodiment in that a temperature sensor 75 is provided, a temperature correlation map 92a and a target pressure map 92b are prestored in the ROM 92 and, as shown in FIG 8, steps S12 and SI 3 are additionally executed and step SI 5a is executed instead of step SI 5 in the pressure regulating process.
  • the other configuration of the second embodiment is the same as that of the first embodiment.
  • the target pressure is set in consideration of the fact that the water vapor partial pressure in the cathode pressure varies with a variation in temperature of the fuel cell stack 10 after a stop of power generation.
  • the temperature sensor 75 shown in FIG 7 measures the outside air temperature and then transmits the measured outside air temperature to the control unit 90.
  • the temperature correlation map 92a is a map that correlates the outside air temperature with the temperature of the fuel cell stack 10 after the fuel cell stack 10 is left standing. Generally, after a stop of power generation, the temperature of the fuel cell stack 10 gradually decreases and finally reaches a stationary constant temperature (hereinafter, referred to as "post-standing stack temperature").
  • the post-standing stack temperature depends on the outside air temperature, so, in the present embodiment, the correlation between the outside air temperature and the post-standing stack temperature is empirically obtained in advance, and is stored in the ROM 92 as the temperature correlation map 92a.
  • the target pressure map 92b is a map that correlates the post-standing stack temperature with the target pressure.
  • FIG 9 is a graph that schematically illustrates the details set in the target pressure map 92b according to the second embodiment.
  • the upper graph shows a target pressure when the post-standing stack temperature is a relatively high temperature Tl
  • the lower graph shows a target pressure when the post-standing stack temperature is a relatively low temperature T2.
  • the left bar indicates a cathode pressure immediately after the pressure regulating process is executed
  • the right bar indicates a cathode pressure after a lapse of a long period of time from when the pressure regulating process is executed.
  • a relatively low pressure Ptl is set as a target pressure for the relatively high temperature Tl as the post-standing stack temperature.
  • a relatively high pressure Pt2 is set as a target pressure for the relatively low temperature T2 as the post-standing stack temperature.
  • the reason of such setting is as follows. As the temperature of the fuel cell stack 10 decreases, the saturated water vapor pressure in each cathode layer 114 decreases, so the water vapor partial pressure further decreases. Thus, the total partial pressure of gases, other than the oxygen partial pressure, within the cathode pressure decreases as the post-standing stack temperature decreases.
  • a higher target pressure is set as the post-standing stack temperature decreases. This prevents the cathode pressure (total pressure) after a lapse of a long period of time from when the pressure regulating process is executed from becoming lower than the atmospheric . pressure (from becoming a negative pressure) irrespective of a decrease in water vapor partial pressure.
  • the pressure regulating unit 91a acquires the ' outside air temperature from a measured value transmitted from the temperature sensor 75 (step SI 2).
  • the pressure regulating unit 1a consults the temperature correlation map 92a for the acquired outside air temperature to estimate the post-standing stack temperature (step SI 3).
  • the pressure regulating unit 91a consults the target pressure map 92b for the acquired atmospheric pressure and the post-standing stack temperature to deterrnine the target pressure (step SI 5a).
  • the process after the target pressure is set is the same as that of the above described steps S20 to S35.
  • the cathode pressure after a lapse of a long period of time is the atmospheric pressure Pa.
  • the post-standing stack temperature is the relatively low temperature T2
  • a decrease in water vapor partial pressure after the pressure regulating process is relatively large.
  • the cathode pressure is increased to the relatively high pressure Pt2 through the pressure regulating process, the total partial pressure of gases, other than oxygen and water vapor, in air may be relatively high.
  • the cathode pressure after a lapse of a long period of time is the atmospheric pressure Pa as in the 1 case where the post-standing stack temperature is Tl.
  • the thus configured fuel cell system 100a according to the second embodiment has similar advantageous effects to those of the fuel cell system 100 according to the first embodiment
  • the fuel cell system 100a is configured so that the post-standing stack temperature is estimated and, when the estimated post-standing stack temperature is relatively low, the target pressure is set to be relatively high.
  • the total partial pressure of gases, other than oxygen and water vapor, in air may be relatively high, so, even when a decrease in water vapor partial pressure after the pressure regulating process is relatively large, the cathode pressure after a lapse of a long period of time may be made to coincide with the atmospheric pressure.
  • the cathode pressure from becoming lower than the atmospheric pressure (from becoming a negative pressure).
  • FIG 10 is a view that schematically illustrates a method of determining a target pressure according to a third embodiment.
  • a fuel cell system (not shown) according to the third embodiment differs from the fuel cell system 100 according to the first embodiment in a method of detennining the target pressure.
  • the other configuration of the fuel cell system according to the third embodiment is the same as that of the fuel cell system 100 according to the first embodiment.
  • the target pressure is determined by the following mathematical expression (2).
  • the average pressure in the cathode layers 114 and the anode layers 113 becomes higher than or equal to the atmospheric pressure. This may prevent the cathode pressure from becoming lower than the atmospheric pressure (from becoming a negative pressure).
  • the anode gas supply flow passage 53 and the anode gas exhaust flow passage 54 may be shut of In the present embodiment, the anode gas supply flow passage 53 is shut off in such a manner that the opening degree of the shut-off valve 63 becomes zero during a stop of power generation.
  • the anode gas exhaust flow passage 54 may be, for example, shut off along with shutting off the cathode gas exhaust flow passage 52 in step S20 shown in FIG 4.
  • the target pressure is determined on the assumption that air is supplied by the air compressor 30 not only to the cathode layers 114 but also to the anode layers 113, so, even when migration of air from the cathode layers 114 to the anode layers 113 occurs, it is possible to prevent the cathode pressure from becoming a negative pressure.
  • the cathode gas supply flow passage 51 and the cathode gas exhaust flow passage 52 are shut off through the pressure regulating process; however, the aspects of the invention are not limited to this configuration.
  • the air compressor 30 is continuously driven without shutting off the cathode gas exhaust flow passage 52 to thereby keep the cathode pressure at the target pressure (excluding a decrease in total pressure due to consumption of oxygen).
  • the air compressor 30 and the pressure regulating unit 91a correspond to a pressure regulating device according to the aspects of the invention
  • the pressure at which the total partial pressure of gases, other than the partial pressure of oxygen, coincides with the atmospheric pressure is set as the target pressure; instead, a pressure higher than the pressure at which the total partial pressure of gases, other than the partial pressure of oxygen, coincides with the atmospheric pressure may be set as the target pressure.
  • a selected pressure regulating device that regulates the total pressure in the cathode layers so that the total partial pressure that is the total of partial pressures of gases, other than the oxygen partial pressure, in the cathode layers becomes higher than or equal to me atmospheric pressure after a stop of power generation of the fuel cell may be employed for the fuel cell system according to the aspects of the invention.
  • the target pressure may be varied in accordance with the degree of degradation of the electrolyte membranes 112. As the electrolyte membranes 112 degrade over time, there is a possibility that the electrolyte membranes 112 may break even when a difference in pressure between each cathode layer 114 and a corresponding one of the anode layers 113 is relatively small. Then, it is applicable that, before the start of the pressure regulating process (or prior to SI 5 in the pressure 1 000066
  • the degree of degradation of the electrolyte membranes 112 is estimated and, when the degree of degradation is large, the target pressure is decreased so as to reduce the difference in pressure.
  • the degree of degradation of the electrolyte membranes 112 may be, for example, estimated on the basis of an accumulated value of past amounts of power generation.
  • the cathode back pressure regulating valve 61 is used to shut off the cathode gas exhaust flow passage 52; however, it is applicable that, instead of the cathode back pressure regulating valve 61 or in addition to the cathode back pressure regulating valve 61, a shut-off valve is provided in the cathode gas exhaust flow passage 52 and then the shut-off valve is used to shut off the cathode gas exhaust flow passage 52.
  • the air compressor 30 is used to suppress flow of cathode gas in the cathode gas supply flow passage 51 ; instead, it is applicable that a shut-off valve is provided in the cathode gas supply flow passage 51 and then the shut-off valve is used to shut off the cathode gas supply flow passage 51.
  • a shut-off valve is provided in the cathode gas supply flow passage 51 and then the shut-off valve is used to shut off the cathode gas supply flow passage 51.
  • both the cathode gas supply flow passage 51 and the cathode gas exhaust flow passage 52 are shut off, and there is no flow of air between the cathode gas supply flow passage 51 and the cathode gas exhaust flow passage 52; however, the aspects of the invention are not limited to this configuration.
  • FIG 11 is a view that illustrates the schematic configuration of a fuel cell system according to the third alternative embodiment.
  • the fuel cell system 100b according to the third alternative embodiment differs from the fuel cell system 100 according to the first embodiment in that a bypass flow passage 81 , an air pump 83 and a flow rate regulating valve 82 are provided.
  • the other configuration of the third alternative embodiment is the same as that of the first embodiment
  • the bypass flow passage 81 is an air flow passage that connects the cathode gas exhaust flow passage 52 to the cathode gas supply flow passage 51.
  • the connection point between the bypass flow passage 81 and the cathode gas exhaust flow passage 52 is located in the cathode gas exhaust flow passage 52 at a portion closer to the fuel cell stack 10 than the cathode back pressure regulating valve 61.
  • the connection point between the bypass flow passage 81 and the cathode gas supply flow passage 51 is located in the cathode gas supply flow passage 51 at a portion closer to the fuel cell stack 10 than the air compressor 30.
  • the flow rate regulating valve 82 is arranged in the bypass flow passage 81, and adjusts the flow rate of air that flows through the bypass flow passage 81.
  • the air pump 83 is arranged in the bypass flow passage 81, and pumps redundant air, exhausted from the cathode gas exhaust flow passage 52, to the cathode gas supply flow passage 51 via the bypass flow passage 81.
  • the pressure regulating unit 91a executes step S35 and then drives the air pump 83 in the pressure regulating process shown in FIG 4.
  • each single cell 11 oxygen in residual air in the cathode layer 114 is consumed by the reaction with hydrogen gas that migrates to the cathode layer 114; however, variations in reaction can possibly occur among the single cells or within each single cell.
  • redundant air is circulated to increase the opportunity of reaction between oxygen in redundant air and permeated hydrogen gas to thereby suppress variations in occurrence of reaction between residual oxygen and migrated hydrogen gas (oxygen consumption).
  • the outside air temperature is correlated with the post-standing stack temperature
  • the post-standing stack temperature (and the atmospheric pressure) is correlated with the target pressure
  • the saturated water vapor pressure may be correlated with the outside air temperature and the target pressure.
  • the correlation between the outside air temperature and the saturated water vapor pressure (water vapor partial pressure) after a lapse of a long period of time from completion of the pressure regulating process is empirically obtained in advance and mapped
  • the correlation between the saturated water vapor pressure (water vapor partial pressure) and the target pressure is empirically obtained in advance and mapped.
  • the temperature correlated with the post-standing stack temperature is the outside air temperature; however, a temperature at another location may be employed instead of the outside air temperature. For example, a temperature at a location in which the fuel cell system 100 is installed, which is spaced a predetermined distance apart from the fuel cell stack 10 and which is not in direct contact with outside air, may be employed.
  • the post-standing stack temperature can be a temperature higher than the outside air temperature.
  • the pressure regulating process is executed after a stop of power generation of the fuel cell stack 10; instead, drying process ma be executed in addition to the pressure regulating process.
  • the air compressor 30 is driven to supply air to the fuel cell stack 10 to thereby scavenge and dry the cathode layer 114 of each single cell 11.
  • the above described pressure regulating process is executed.
  • scavenging may be performed using inert gas, such as nitrogen gas, instead of air.
  • each electrolyte membrane 112 from the anode layer 113 and migrates to the cathode layer 114 reacts with oxygen in redundant air in each cathode layeT 114 to thereby produce water. If the water remains in the cathode layers 114, there may be a problem that the cathode layers 114 f eeze in a low-temperature environment to, for example, cause the performance of power generation to degrade at the time of the subsequent start-up. Then, by employing the above configuration, produced water in each cathode layer 114 may be drained, so it is possible to suppress freezing, or the like, of residual water.
  • the above drying process may be executed after the temperature of the fuel cell stack 10 has decreased to around the outside air temperature.
  • the above configuration not only water produced by the reaction between permeated hydrogen gas and oxygen in redundant air but also water condensed with a decrease in temperature may be removed, so it is possible to further suppress freezing, or the like, of residual water.
  • the pressure regulating process is executed after a stop of power generation of the fuel cell stack 10; instead, degradation of the fuel cell stack 10 (electrolyte membranes 112) may be determined in addition to the pressure regulating process.
  • degradation of the electrolyte membranes 112 proceeds (for example, when the thickness of each membrane reduces because of continuously applied pressure in the stacking direction), migration of gas via the electrolyte membranes 112 easily occurs.
  • the amount of air that migrates from the cathode layers 114 to the anode layers 113 via the electrolyte membranes 112 increases when air is supplied from the air compressor 30, so the rate of increase in the cathode pressure decreases. Then, the rate of increase in the cathode pressure in the pressure regulating process is measured to thereby make it possible to determine the degree of degradation of the electrolyte membranes 112 on the basis of the measured rate of increase in the cathode pressure.
  • the correlation between the degree of degradation of the electrolyte membranes 112 and the rate of increase in the cathode pressure is empirically obtained in advance and mapped and then the degree of degradation may be determined by consulting the map for the measured rate of increase in the cathode pressure.
  • the rate of increase in the cathode pressure may be, for example, measured in such a manner that a measured value of the second pressure sensor 72 is sequentially recorded at a predeterrnined interval (for example, at an interval of five seconds) and then a difference between the temporally adjacent measured values is obtained.
  • the pressure regulating process is definitely executed after a stop of power generation of the fuel cell stack 10; however, it is possible to execute process of determining whether to execute the pressure regulating process before executing the pressure regulating process. Specifically, for example, it is applicable that the temperature of the fuel cell stack 10 is measured, and, when the temperature of the fuel cell stack 10 is lower than a predetermined temperature, the pressure regulating process is not executed. When the temperature of the fuel cell stack 10 is relatively low, the degree of activation of the catalyst layer in each cathode layer 114 is low.
  • a period from a stop of power generation of the fuel cell stack 10 to a restart-up of the fuel cell stack 10 is estimated and, when the estimated period is shorter than a predetermined period, the pressure regulating process is not executed.
  • a certain period is required from when power generation of the fuel cell stack 10 is stopped to when oxygen in residual air is consumed to cause the pressure in the cathode layers 114 to become a negative pressure.
  • the pressure in the cathode layers 114 does not become a negative pressure.
  • the period from when power generation of the fuel cell stack 10 is stopped to when the fuel cell stack 10 restarts up may be, for example, estimated on the basis of a time, day of week, and the like, at the time of a stop of power generation of the fuel cell stack 10 from a past operation history of the fuel cell stack 10.
  • the degree of degradation of the electrolyte membranes 112 is estimated and, when the degree of degradation is larger than a predetermined value, the pressure regulating process is not executed.
  • the degree of degradation of the electrolyte membranes 112 may be, for example, estimated on the basis of an accumulated value of past amounts of power generation.
  • the atmospheric pressure is measured in the pressure regulating process (step S10); however, measurement of the atmospheric pressure may be omitted.
  • the above configuration may also be employed.
  • process of measuring the atmospheric pressure may be omitted, so a period of time required for the pressure regulating process may be reduced, and the fourth pressure sensor 74 may be omitted, so it is possible to reduce manufacturing cost of the fuel cell system 100 or 100a.
  • the target pressure is determined on the basis of the volume Vc of the cathode layers 114 and the volume Va of the anode layers; instead, . the target pressure may be determined (calculated) on the basis of the volume of the gas diffusion layers in the cathode layers 114 and the volume of the gas diffusion layers in the anode layers 113.
  • the gas diffusion layers in the cathode layers 114 correspond to a cathode layer according to the aspects of the invention.
  • the gas diffusion layers in the anode layers 113 correspond to an anode layer according to the aspects of the invention.
  • the target pressure is determined on the basis of not only the volume Vc of the cathode layers 114 and the volume Va of the anode layer but also the volumes of the cathode gas supply manifold 511, cathode gas exhaust manifold 521, anode gas supply manifold (not shown) and anode gas exhaust manifold (not shown).
  • the fuel cell system 100 or 100a is equipped for an electric vehicle; instead, the fuel cell system may be applied to various mobile units, such as a hybrid vehicle, a ship and a robot.
  • the fuel cell stack 10 is used as a stationary power supply and then the fuel cell system 100 or 100a is applied to an architecture, such as a building and a general house.
  • part of the configuration implemented by software may be replaced with hardware.
  • part of the configuration implemented by hardware may be replaced with software.

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Abstract

L'invention concerne un système de piles à combustible (100) comprenant : une pile à combustible (10) qui comprend une membrane électrolytique, une couche cathodique qui est en contact avec la membrane électrolytique et qui fournit un gaz de réaction cathodique, contenant de l'oxygène, à la membrane électrolytique, et une couche anodique qui est en contact avec la membrane électrolytique sur un côté opposé de la membrane électrolytique par rapport à un côté de la membrane électrolytique sur laquelle la couche cathodique est disposée et qui fournit du gaz de réaction anodique à la membrane électrolytique ; et un dispositif de régulation de pression (30, 91a, 91b, 51, 52, 61) qui, après un arrêt de la production d'électricité de la pile à combustible (10), régule une pression totale dans la couche cathodique de sorte qu'une pression partielle totale qui est un total de pressions partielles de gaz, autre qu'une pression partielle d'oxygène, dans la couche cathodique, est supérieure ou égale à une pression atmosphérique.
PCT/IB2011/000066 2010-01-19 2011-01-18 Système de piles à combustibles et son procédé de commande WO2011089502A1 (fr)

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CN107004873B (zh) * 2014-11-24 2020-02-21 阿海珐能量存储公司 用于控制燃料电池的方法及相关联的燃料电池系统
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CN107004873A (zh) * 2014-11-24 2017-08-01 阿海珐能量存储公司 用于控制燃料电池的方法及相关联的燃料电池系统
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WO2017129906A1 (fr) * 2016-01-26 2017-08-03 Safran Power Units Système de régulation de pression, ensemble de pile à combustible et utilisation du système de régulation
FR3074363A1 (fr) * 2017-11-28 2019-05-31 Safran Power Units Pile a combustible comprenant un dispositif de regulation de pression et procede de regulation de pression
WO2019106010A1 (fr) * 2017-11-28 2019-06-06 Safran Power Units Pile a combustible comprenant un dispositif de regulation de pression et procede de regulation de pression
US11302943B2 (en) 2017-11-28 2022-04-12 Safran Power Units Fuel cell comprising a pressure regulating device and method for regulating pressure
CN112993327A (zh) * 2021-05-10 2021-06-18 北京亿华通科技股份有限公司 一种燃料电池系统的控制方法和装置
CN112993327B (zh) * 2021-05-10 2021-07-30 北京亿华通科技股份有限公司 一种燃料电池系统的控制方法和装置
WO2022253790A2 (fr) 2021-06-02 2022-12-08 Safran Power Units Procédé et module de commande d'une vanne de régulation de la pression interne d'un circuit de fluide dans un dispositif électrochimique
FR3123764A1 (fr) * 2021-06-02 2022-12-09 Safran Power Units Procédé et module de commande d’une vanne de régulation de la pression interne d’un circuit de fluide dans un dispositif électrochimique
WO2022253790A3 (fr) * 2021-06-02 2023-03-09 Safran Power Units Procédé et module de commande d'une vanne de régulation de la pression interne d'un circuit de fluide dans un dispositif électrochimique

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