Abstract: A reference electrode is provided adjacent to an anode of a membrane electrode assembly. The potential difference between the reference electrode and the anode is measured by a control unit. The control unit compares the measured value and a map of the anode potential difference stored in the control unit. When the measured value indicates a relation line which is different from a reference line indicating that the fuel gas is sufficient, it is judged that shortage of the fuel gas occurs.

Abstract: A fuel cell stack includes a stack body, an end separator, a terminal plate, an insulating plate, and an end plate provided at one end of the stack body in a stacking direction. The insulating plate has a recess for accommodating the terminal plate. Further, the insulating plate has a bypass passage connected between a fuel gas supply passage and a fuel gas discharge passage outside the recess for discharging condensed water. An insulating seal member is provided on the end separator to cover the bypass passage. The condensed water flows through an insulated passage formed by the insulating seal member and the bypass passage.

Abstract: A fuel cell stack includes a first end power generation unit and a first dummy unit adjacent to a power generation unit at one end of a stack body in a stacking direction. In the first end power generation unit, a first separator is stacked on the power generation unit, a first membrane electrode assembly is stacked on the first separator, a second separator is stacked on the first membrane electrode assembly, an electrically conductive plate is stacked on the second separator, and a third separator is stacked on the electrically conductive plate. A coolant is supplied to a coolant flow field formed between the power generation unit and the first end power generation unit, for cooling a second membrane electrolyte assembly of the power generation unit and the first membrane electrode assembly of the first end power generation unit.

Abstract: A first metal separator of a fuel cell comprises a metal plate, and a first seal member is formed integrally on both surfaces of an outer edge of the metal plate. A first rib having a frame shape is provided around an oxygen-containing gas supply passage or the like of the metal plate. The first rib has a rib surface spaced away from an inner end surface of the metal plate around the oxygen-containing gas supply passage or the like, toward the oxygen-containing gas supply passage or the like.

Abstract: A fuel cell stack is provided with an outlet side oxygen-containing gas communication hole. First and second oxygen-containing gas flow passage grooves are provided in the direction of the gravity while meandering in the horizontal direction on a surface of a first separator. The second oxygen-containing gas flow passage grooves communicate with the outlet side oxygen-containing gas communication hole via second oxygen-containing gas connecting flow passages. A porous water-absorbing tube, which is used to discharge water to the outside of the fuel cell stack in accordance with the capillary phenomenon and the difference in pressure of air, is provided for the outlet side oxygen-containing gas communication hole.

Abstract: A fuel cell system includes a fuel cell and a supplying unit, which supplies reactive gases to the fuel cell. A control unit includes a power production effective area calculator calculates the areas of the electrodes available for power production as a power production effective area. A current density calculator which calculates a current density of the power production effective area calculated by the power production effective area calculator based on the total amount of power required by the fuel cell. A gas supply amount determiner determines the amount of reactive gas to be supplied to the fuel cell depending on the current density. A gas supply controller controls the supplying unit so as to supply the amount of reactive gas determined by the gas supply amount determiner to the fuel cell.

Abstract: A method of actuating a fuel cell system equipped with a fuel cell is disclosed. The fuel cell system is supplied with reaction gases for generating electricity. The method includes the steps of: a first step for actuating the fuel cell in a low-temperature actuation mode to thereby warm up the fuel cell, if a low-temperature actuation condition is satisfied at a start-up of the fuel cell; and a second step for drying a membrane electrode assembly of the fuel cell, if a power generation capacity of the fuel cell is lower than a predetermined power generation capacity.

Abstract: A fuel cell stack which comprises a plurality of unit fuel cells laminated via separators, and is connected to external resistors each allowing a feeble current to flow to each unit fuel cell, whereby such problems as an open-circuit voltage generation and corrosion that may be caused by fuel gas remaining after operation shutdown can be resolved. A switch is preferably attached in series with an external resistor.

Abstract: An electrode for a solid polymer fuel cell includes a gas diffusion layer, an electrode catalyst layer disposed between a solid polymer membrane of the fuel cell and the gas diffusion layer, and a water-holding layer disposed between the gas diffusion layer and the electrode catalyst layer. Under high-relative humidity conditions of reaction gases, flooding can be prevented because the electrode catalyst layer is made porous, while under low-relative humidity conditions of reaction gases, sufficient water contents can be stably provided thanks to the water-holding layer so that proton conductivity of the solid polymer membrane can be maintained appropriately. Consequently, high-performance and high-durability electrode and membrane electrode assembly for a solid polymer fuel cell can be provided such that the performance and the durability thereof are not affected by change in relative humidity in reactant gases supplied to the solid polymer fuel cell.

Abstract: A fuel cell stack which comprises a plurality of unit fuel cells laminated via separators, and is connected to external resistors each allowing a feeble current to flow to each unit fuel cell, whereby such problems as an open-circuit voltage generation and corrosion that may be caused by fuel gas remaining after operation shutdown can be resolved. A switch is preferably attached in series with an external resistor.

Abstract: After an ignition switch is turned off, in order to suppress operation of an air compressor and thereby reduce noise, liquid droplets residing in an oxygen-containing gas flow field as well as liquid droplets residing in a fuel gas flow field are removed during separate time periods, such that the flow rate in the oxygen-containing gas flow field and the flow rate in the fuel gas flow field do not become large at the same time. Then, an electrolyte membrane is dried using an oxygen-containing gas, in order to improve the performance upon starting a next operation.

Abstract: A fuel cell system includes a fuel cell, an operation controller, a checking unit, a scavenging unit, an instructing unit, a temperature sensor, a humidifier and a humidification controller. The operation controller selects one of a normal operation mode and a low-temperature operation mode. The checking unit determines whether the fuel cell has been started up in the low-temperature operation mode. The instructing unit provides an instruction for a shutoff of electricity generation. When the scavenging unit conducts scavenging based on the checking unit determining that the fuel cell has been started in the low-temperature operation mode in response to an instruction for a shutoff of electricity generation and an actual temperature of the fuel cell is higher than a predetermined temperature, the humidification controller controls an amount of humidification according to the actual temperature.

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: A stop method for a fuel cell system including a fuel cell unit in which hydrogen is supplied to an anode, and air is supplied to a cathode so as to generate electrical power via an electrochemical reaction. The stop method includes the steps of stopping supply of hydrogen to the anode, electrically connecting the anode and the cathode via an electrical load, and supplying air to the anode.

Abstract: A fuel cell stack includes a stacked body, a negative and positive terminal plates stacked on opposite ends of the stacked body, insulators disposed outside the terminal plates, and the end plates disposed outside the end plates. The insulator includes a first insulator plate, a second insulator plate, and a third insulator plate. Bypass passages are formed on the first insulator plate and the third insulator plate for discharging water in an oxygen-containing gas and water in a fuel gas.

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 stacked body is formed by stacking a plurality of power generation cells in a stacking direction. End power generation cells are provided at opposite ends of the stacked body in the stacking direction. Each of the power generation cells includes a membrane electrode assembly and first and second metal separators sandwiching the membrane electrode assembly therebetween. The end power generation cells include first outer separators and second outer separators. The first outer separators are more highly hydrophilic in comparison with the first and second metal separators of the power generation cells.

Abstract: A fuel cell stack includes a stack body, an end separator, a terminal plate, an insulating plate, and an end plate provided at one end of the stack body in a stacking direction. The insulating plate has a recess for accommodating the terminal plate. Further, the insulating plate has a bypass passage connected between a fuel gas supply passage and a fuel gas discharge passage outside the recess for discharging condensed water. An insulating seal member is provided on the end separator to cover the bypass passage. The condensed water flows through an insulated passage formed by the insulating seal member and the bypass passage.

Abstract: A fuel cell stack includes a stack body formed by stacking a plurality of power generation cells in a stacking direction. At one end of the stack body, first and second dummy cells are provided. At the other of the stack body, third and fourth dummy cells are provided. Each of the first to fourth dummy cells includes a first metal separator and a second metal separator. The first metal separator and a first metal separator of the power generation cell have substantially the same shape. The second metal separator and a second metal separator of the power generation cell have substantially the same shape.

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.