Abstract: A fuel cell stack includes a stack body formed by stacking a plurality of power generation cells in a stacking direction. At opposite ends of the stack body in the stacking direction, end power generation cells are provided. An end coolant flow field is formed on a separator of the end power generation cell. The flow rate of the coolant in the end coolant flow field is smaller than the flow rate of the coolant in a coolant flow field in each of the power generation cells. Specifically, the number of flow grooves of the end coolant flow field is smaller than the number of flow grooves of the coolant flow field.

Abstract: An oxygen-containing gas flow field is formed on a surface of a first metal separator. The oxygen-containing gas flow field is connected between an oxygen-containing gas supply passage and an oxygen-containing gas discharge passage. The oxygen-containing gas flow field comprises oxygen-containing gas flow grooves, and ends of the oxygen-containing gas flow grooves are extended outwardly beyond ends of electrode catalyst layer of a membrane electrode assembly, and connected to an inlet buffer and an outlet buffer. When the purging process is performed at the time of stopping operation of the fuel cell, the purging air supplied to the oxygen-containing gas flow field discharges water retained in the electrode catalyst layers from the ends to the outlet buffer.

Abstract: A method of operating a fuel cell assembly and a fuel cell system use a simple construction to restrain deterioration of power generating performance of a fuel cell assembly at a startup in a subfreezing environment. If an ignition switch is turned off is STEP 1, a control unit determines in STEP 3 whether the temperature of a fuel cell assembly (the internal temperature of the fuel cell assembly) is lower than a predetermined temperature, which is higher than the temperature at which the water produced during power generation freezes. If the internal temperature of the fuel cell assembly is the predetermined temperature or higher, then the processing proceeds to STEP 4 wherein a power generating condition is adjusted to cause the internal temperature of the fuel cell assembly to rise. In STEP 5, an alarm device is actuated.

Abstract: A bypass plate and an intermediate plate are interposed between a stack body and a negative electrode terminal of a fuel cell stack. An oxygen-containing gas passage extends through the bypass plate and the stack body. The intermediate plate has a small opening. The opening has a cross sectional area smaller than a cross sectional area of the oxygen-containing gas supply passage. The opening is formed by an extension extending into the oxygen-containing gas supply passage. The extension removes water in the oxygen-containing gas, and discharges the water into a bypass flow passage.

Abstract: An oxygen-containing gas flow field is formed on a surface of a first metal separator. The oxygen-containing gas flow field is connected between an oxygen-containing gas supply passage and an oxygen-containing gas discharge passage. The oxygen-containing gas flow field comprises oxygen-containing gas flow grooves, and ends of the oxygen-containing gas flow grooves are extended outwardly beyond ends of electrode catalyst layer of a membrane electrode assembly, and connected to an inlet buffer and an outlet buffer. When the purging process is performed at the time of stopping operation of the fuel cell, the purging air supplied to the oxygen-containing gas flow field discharges water retained in the electrode catalyst layers from the ends to the outlet buffer.

Abstract: A fuel cell stack includes a stack body formed by stacking a plurality of power generation cells in a stacking direction. At opposite ends of the stack body in the stacking direction, end power generation cells are provided. An end coolant flow field is formed on a separator of the end power generation cell. The flow rate of the coolant in the end coolant flow field is smaller than the flow rate of the coolant in a coolant flow field in each of the power generation cells. Specifically, the number of flow grooves of the end coolant flow field is smaller than the number of flow grooves of the coolant flow field.

Abstract: A method of operating a fuel cell assembly and a fuel cell system use a simple construction to restrain deterioration of power generating performance of a fuel cell assembly at a startup in a subfreezing environment. If an ignition switch is turned off is STEP 1, a control unit determines in STEP 3 whether the temperature of a fuel cell assembly (the internal temperature of the fuel cell assembly) is lower than a predetermined temperature, which is higher than the temperature at which the water produced during power generation freezes. If the internal temperature of the fuel cell assembly is the predetermined temperature or higher, then the processing proceeds to STEP 4 wherein a power generating condition is adjusted to cause the internal temperature of the fuel cell assembly to rise. In STEP 5, an alarm device is actuated.

Abstract: In order to improve detecting accuracy in a gas leak detection for a fuel cell, in a gas leak detection method for a fuel cell having a solid polymer electrolyte membrane sandwiched by an anode and a cathode, an output voltage is measured in an activated over-potential region in a state in which the pressure of fuel gas which is supplied to the anode is maintained higher than the pressure of gas which is supplied to the cathode, and a gas leak is determined to exist when the output voltage is lower than a predetermined pressure value.

Abstract: The present invention provides a fuel stack comprising: a plurality of fuel cell units stacked together in a direction of stacking each of which comprises an electrolyte element, a pair of electrodes holding the electrolyte element therebetween, and a pair of separators holding the electrodes therebetween; a pair of terminal plates each of which is disposed outside an end fuel cell unit located at an end of the stacked fuel cell units; and a terminal element extending outwardly in the direction of stacking from the outside surface of at least one of the terminal plates; wherein the location from which the terminal element extends is located within an area on the terminal plate, corresponding to an area in a passage for an oxidizing gas formed in the end fuel cell unit disposed adjacent to the terminal element where the partial pressure of water vapor is lower than the saturated water vapor pressure.

Abstract: A bypass plate and an intermediate plate are interposed between a stack body and a negative electrode terminal of a fuel cell stack. An oxygen-containing gas passage extends through the bypass plate and the stack body. The intermediate plate has a small opening. The opening has a cross sectional area smaller than a cross sectional area of the oxygen-containing gas supply passage. The opening is formed by an extension extending into the oxygen-containing gas supply passage. The extension removes water in the oxygen-containing gas, and discharges the water into a bypass flow passage.

Abstract: In order to improve detecting accuracy in a gas leak detection for a fuel cell, in a gas leak detection method for a fuel cell having a solid polymer electrolyte membrane sandwitched by an anode and a cathode, an output voltage is measured in an activated over-potential region in a state in which the pressure of fuel gas which is supplied to the anode is maintained higher than the pressure of gas which is supplied to the cathode, and a gas leak is determined to exist when the output voltage is lower than a predetermined pressure value.

Abstract: The present invention provides a fuel stack comprising: a plurality of fuel cell units stacked together in a direction of stacking each of which comprises an electrolyte element, a pair of electrodes holding the electrolyte element therebetween, and a pair of separators holding the electrodes therebetween; a pair of terminal plates each of which is disposed outside an end fuel cell unit located at an end of the stacked fuel cell units; and a terminal element extending outwardly in the direction of stacking from the outside surface of at least one of the terminal plates; wherein the location from which the terminal element extends is located within an area on the terminal plate, corresponding to an area in a passage for an oxidizing gas formed in the end fuel cell unit disposed adjacent to the terminal element where the partial pressure of water vapor is lower than the saturated water vapor pressure.