Abstract: A fuel cell system (10) includes: a fuel cell (1); a hydrogen supply device (2) for supplying a hydrogen gas to the fuel cell (1); an anode off-gas passage (22) through which an anode off-gas discharged from the anode side of the fuel cell (1) passes; a hydrogen concentration sensor (3) that measures the concentration of hydrogen in the anode off-gas; and a sensor correction device (4) that, after a predetermined time has elapsed since the hydrogen gas supply to the fuel cell by the hydrogen supply device (2) was stopped, measures the hydrogen concentration using the hydrogen concentration sensor (3), and corrects a measurement value from the hydrogen concentration sensor (3) based on the measured hydrogen concentration.

Abstract: In a fuel cell system (10), an anode exhaust gas discharge pipe (50) is full of hydrogen at the start of operation of a fuel cell (20). As time passes when the fuel cell (20) is operating, the concentration of impurities within the anode exhaust gas discharge pipe (50) increases. When the hydrogen concentration is less than a reference concentration for opening a valve, an upstream cut-off valve (61) closes and a downstream cut off valve (62) opens. As a result, the impurity concentration in the anode gas discharge pipe (50) quickly drops and is restored to the level that it was at the start of operation of the fuel cell (20). This sudden drop in the impurity concentration is caused by a pressure difference between the pressure in the anode exhaust gas pipe (50) and the pressure of the outside air, and the concentration gradient.

Abstract: A fuel cell system capable of proper driving even at times of low temperature, below freezing or the like. The fuel cell system includes a fuel cell stack, piping, a pressure regulator, and a control unit. The piping discharges hydrogen or air that is used in electricity generation from the fuel cell stack. The pressure regulator regulates pressure of gases which are supplied and discharged to and from the fuel cell stack in accordance with the size of a load. The control unit judges whether or not there is a likelihood of the pressure regulator freezing, and when it is judged that there is a likelihood of freezing, prohibits a degree of openness of the pressure regulator from going below a predetermined degree of openness.

Abstract: When an operation of a fuel cell system (100) is stopped, a flow of cathode off-gas into a circulation passage (28) is stopped. A stopped state of the flow of the cathode off-gas into the circulation passage (28) is held even after a start-up of the system (100) until the fuel cell (10) is brought into a predetermined state. Such structure prevents an outlet (52) of a three-way valve (50) from being frozen in an opened state. Accordingly the cathode off-gas that contains large amount of water and nitrogen hardly flows into the fuel cell (10) accidentally. This makes it possible to restrain various types of trouble, for example, generation of flooding upon start-up of the system, decrease in the oxygen partial pressure, and decrease in the power generation efficiency resulting therefrom.

Abstract: To provide a fuel cell system that achieves both prevention of degradation of the performance of a fuel cell due to accumulation of an impurity in an anode gas flow channel and reduction of the amount of discharged fuel gas to the outside of the system. A downstream end of the anode gas flow channel can be opened and closed by an exhaust valve 14. The exhaust valve 14 can be selectively switched between an exhaust mode in which a substantially smaller amount of gas than the consumption of the fuel gas in the anode gas flow channel is discharged to the outside of the system and a closed mode in which communication between the anode gas flow channel and the outside of the system is blocked. In operation of a fuel cell 2, whether there is a downstream flow of the impurity in the anode gas flow channel is detected. If there is a downstream flow of the impurity detected, the exhaust mode is selected. Until a downstream flow of the impurity is detected, the exhaust valve 14 is in the closed mode.

Abstract: A fuel cell having a stack structure is provided. The fuel cell includes plural unit cells each of which includes an anode and a cathode which are provided on both sides of a predetermined electrolyte membrane, and a catalytic layer which is provided in at least one of the anode and the cathode, and which supports a catalyst for promoting an anode reaction or a cathode reaction, the plural unit cells being stacked to form a stack structure. In the fuel cell, the plural unit cells include a unit cell including a catalyst layer supporting a catalyst which is different from catalysts supported by catalyst layers of other unit cells in at least one of type, weight, and specific surface area.

Abstract: A fuel cell system includes a fuel cell (1) having a plurality of unit cells (1a) stacked on each other, first and second end plates (1b, 1c) between which the plurality of unit cells are interposed, and a gas supply passage (1d) and a gas discharge passage (1e), both extending in the stacking direction of the unit cells. An inlet (1f) of the gas supply passage (1d) and an outlet (1g) of the gas discharge passage (1e) are located on the first end plate side. A hydrogen concentration sensor (4) is disposed in the gas discharge passage and detects a hydrogen concentration in the gas discharged from the plurality of unit cells. An electricity generation process in the fuel cell is controlled based on the hydrogen concentration detected by a hydrogen concentration sensor (4).

Abstract: A fuel cell system (10) includes: a fuel cell (1); a hydrogen supply device (2) for supplying a hydrogen gas to the fuel cell (1); an anode off-gas passage (22) through which an anode off-gas discharged from the anode side of the fuel cell (1) passes; a hydrogen concentration sensor (3) that measures the concentration of hydrogen in the anode off-gas; and a sensor correction device (4) that, after a predetermined time has elapsed since the hydrogen gas supply to the fuel cell by the hydrogen supply device (2) was stopped, measures the hydrogen concentration using the hydrogen concentration sensor (3), and corrects a measurement value from the hydrogen concentration sensor (3) based on the measured hydrogen concentration.

Abstract: The standard permeation amount of an impurity substance, that is, the permeation amount per unit area of the impurity substance under a standard concentration is calculated from the gas pressures in the gas channels, the impedance, and the fuel cell temperature. The permeation index of the impurity substance at each of locations in the anode-side gas channel is calculated on the basis of the previously calculated value of the concentration distribution of the impurity substance. Then, on the basis of the standard permeation amount and the permeation index, the permeation amounts of the impurity substance at the locations in the anode-side gas channel are calculated. On the basis of a total of the permeation amounts, the amount of the impurity substance accumulated in the anode-side gas channel is calculated.

Abstract: A fuel cell system characterized by including: a fuel cell (1) that generates electricity through electrochemical reactions between a hydrogen gas and an oxidizing gas; a hydrogen supply device (2) for supplying the hydrogen gas to the fuel cell; a hydrogen supply passage (21) through which the hydrogen gas supplied from the hydrogen supply device passes; an anode off-gas passage (22) through which an anode off-gas discharged from the anode side of the fuel cell passes; a hydrogen concentration sensor (3) provided on at least one of the hydrogen supply passage (21) and the anode off-gas passage (22); and a correction device (4) that reduces impurities in the passage provided with the hydrogen concentration sensor, measures hydrogen concentration using the hydrogen concentration sensor and corrects a reference point of the hydrogen concentration sensor based on the measured hydrogen concentration.

Abstract: The present invention has been devised in order to solve the problems described above, and an object of the present invention is to provide a fuel cell system that can discharge an impurity in an anode gas flow channel while suppressing wasteful discharge of a fuel gas to the outside of the system. An exhaust valve is connected to a downstream end of an anode gas flow channel of a fuel cell. The exhaust valve has an exhaust mode in which a substantially smaller amount of gas than the consumption of a fuel gas in the anode gas flow channel is discharged to the outside of the system. After a request to stop electric power generation by the fuel cell, the output current value of the fuel cell is increased to a predetermined value. Then, the exhaust valve is set in the exhaust mode before or when the output current value is increased, and the discharge flow rate of the exhaust valve is increased in accordance with the increase of the output current value.

Abstract: In a fuel cell system (10), an anode exhaust gas discharge pipe (50) is full of hydrogen at the start of operation of a fuel cell (20). As time passes when the fuel cell (20) is operating, the concentration of impurities within the anode exhaust gas discharge pipe (50) increases. When the hydrogen concentration is less than a reference concentration for opening a valve, an upstream cut-off valve (61) closes and a downstream cut off valve (62) opens. As a result, the impurity concentration in the anode gas discharge pipe (50) quickly drops and is restored to the level that it was at the start of operation of the fuel cell (20). This sudden drop in the impurity concentration is caused by a pressure difference between the pressure in the anode exhaust gas pipe (50) and the pressure of the outside air, and the concentration gradient.

Abstract: When an operation of a fuel cell system (100) is stopped, a flow of cathode off-gas into a circulation passage (28) is stopped. A stopped state of the flow of the cathode off-gas into the circulation passage (28) is held even after a start-up of the system (100) until the fuel cell (10) is brought into a predetermined state. Such structure prevents an outlet (52) of a three-way valve (50) from being frozen in an opened state. Accordingly the cathode off-gas that contains large amount of water and nitrogen hardly flows into the fuel cell (10) accidentally. This makes it possible to restrain various types of trouble, for example, generation of flooding upon start-up of the system, decrease in the oxygen partial pressure, and decrease in the power generation efficiency resulting therefrom.

Abstract: A fuel cell system capable of proper driving even at times of low temperature, below freezing or the like. The fuel cell system includes a fuel cell stack, piping, a pressure regulator, and a control unit. The piping discharges hydrogen or air that is used in electricity generation from the fuel cell stack. The pressure regulator regulates pressure of gases which are supplied and discharged to and from the fuel cell stack in accordance with the size of a load. The control unit judges whether or not there is a likelihood of the pressure regulator freezing, and when it is judged that there is a likelihood of freezing, prohibits a degree of openness of the pressure regulator from going below a predetermined degree of openness.

Abstract: A fuel cell system of the present invention performs power generation stoppage control for stopping a power generating operation after generating power for making a temperature of a specified portion of a fuel cell be a specified value or greater when the power generating operation of the fuel cell is stopped.

Abstract: In a fuel cell system, a temperature sensor detects an internal temperature of a fuel cell. A cooling water pump is controlled so that it is stopped when the internal temperature of the fuel cell is equal to or lower than 0 degrees. A driving amount of the cooling water pump increases according to a rise in internal temperature of the fuel cell when the internal temperature is higher than 0 degrees. A degree of increase in driving amount is restrained when the internal temperature of the fuel cell is between 0 degrees and a predetermined temperature higher than 0 degrees.

Abstract: A fuel cell having a stack structure is provided. The fuel cell includes plural unit cells each of which includes an anode and a cathode which are provided on both sides of a predetermined electrolyte membrane, and a catalytic layer which is provided in at least one of the anode and the cathode, and which supports a catalyst for promoting an anode reaction or a cathode reaction, the plural unit cells being stacked to form a stack structure. In the fuel cell, the plural unit cells include a unit cell including a catalyst layer supporting a catalyst which is different from catalysts supported by catalyst layers of other unit cells in at least one of type, weight, and specific surface area.

Abstract: An ECU closes a second relay and third relay while opening a first relay so that a drive motor and a variable resistor are connected in series, when it is determined based on detected accelerator opening &thgr; acc and vehicle speed Vc that a requirement for applying the brake on the vehicle has been made. The drive motor is driven by an external force which is input via wheels of the vehicle, thus operating as a power generation braking device. The ECU sets a variable resistance value Vc based on the accelerator opening &thgr; acc and the vehicle speed Vc. Thus, the electric power generated by the drive motor is consumed via an inverter by the variable resistor whose resistance value Rv has been set to a certain value. Accordingly, the amount of load to be applied on a mechanical braking system of a motor-driven vehicle can be reduced and an improved drivability in decelerating the vehicle can be achieved.

Abstract: In a fuel cell system, a temperature sensor detects an internal temperature of a fuel cell. A cooling water pump is controlled so that it is stopped when the internal temperature of the fuel cell is equal to or lower than 0 degrees. A driving amount of the cooling water pump increases according to a rise in internal temperature of the fuel cell when the internal temperature is higher than 0 degrees. A degree of increase in driving amount is restrained when the internal temperature of the fuel cell is between 0 degrees and a predetermined temperature higher than 0 degrees.