Abstract: Upon stop of electric power generation of a fuel cell a hydrogen shutoff valve is closed, and a cathode is purged. At the same time, an air introducing valve and the purge valve are opened. The air taken in by the compressor is introduced into the anode through the air introducing tube to exhaust the hydrogen remaining in the anode to replace the hydrogen with the air. When the replacement of the hydrogen with the air has been finished, the compressor is turned off and the air introducing valve and the purge valve are opened. After that, if a temperature of the fuel cell is determined to be equal to or lower than a threshold “a”, a cathode-prioritized purge and an anode-prioritized purging are performed.

Abstract: A fuel cell separator plate comprising a portion in contact with an electrode, and a sealing portion provided around the contact portion, the contact portion having a larger surface roughness (Rmax) than that of the sealing portion. It is preferably a molded separator plate made of a composite carbon material comprising carbon and a thermosetting resin.

Abstract: A fuel cell includes cell assemblies connected to each other by a fuel gas connection passage, an oxygen-containing gas connection passage, and a coolant connection passage. A fuel gas adjusting mechanism, an oxygen-containing gas adjusting mechanism, and a coolant adjusting mechanism are connected respectively to the fuel gas connection passage, the oxygen-containing gas connection passage, and the coolant connection passage. These adjusting mechanisms adjust the temperatures in the cell assemblies, the relative humidity in the fuel gas, and the relative humidity in the oxygen-containing gas.

Abstract: Upon stop of electric power generation of a fuel cell a hydrogen shutoff valve is closed, and a cathode is purged. At the same time, an air introducing valve and the purge valve are opened. The air taken in by the compressor is introduced into the anode through the air introducing tube to exhaust the hydrogen remaining in the anode to replace the hydrogen with the air. When the replacement of the hydrogen with the air has been finished, the compressor is turned off and the air introducing valve and the purge valve are opened. After that, if a temperature of the fuel cell is determined to be equal to or lower than a threshold “a”, a cathode-prioritized purge and an anode-prioritized purging are performed.

Abstract: A heat medium passage for controlling the temperature of the electric power generation section is separated from the electric power generation section of a fuel cell including a plurality of separators and electric power generating elements alternately laminated in a lamination direction. A heat plate exchanges heat with at least one of the heat medium passage and a heat medium in the heat medium passage and is connected to the separators to provide electrical conduction between the separators in the lamination direction. An electrical insulator is provided for insulation between the heat medium and the heat plate. Another heat medium passage may be provided on the other side. A temperature control system for the fuel cell may include a burner for supplying the heated heat medium to the heat medium passage and may comprise first and second fluidic passages independently to selectively use the first and second fluidic passage.

Abstract: A fuel cell includes an electrolyte electrode assembly and a pair of first and second separators. First through fourth oxygen-containing gas holes, first through fourth coolant holes, and first through fourth fuel gas holes extend through the fuel cell. The first through fourth oxygen-containing gas holes are selectively used as oxygen-containing gas supply ports or oxygen-containing gas discharge ports to change the flow direction of an oxygen-containing gas in an oxygen-containing gas flow field continuously.

Abstract: A fuel cell stack is formed by stacking a plurality of fuel cells. A heating mechanism is provided for heating an outermost fuel cell by external electrical energy. A power generation circuit including electric heaters corresponding to the fuel cells is provided. Further, a switching mechanism including switches for selectively connecting the fuel cells to the power generation circuit or selectively disconnecting the fuel cells from the power generation circuit is provided.

Abstract: A first separator of a unit cell and a second separator of another unit cell and are disposed adjacent to each other in a stacked assembly. Crest surfaces of straight sections of first hollow ridges of the first separator are in contact with crest surfaces of second hollow ridges of the second separator, and crest surfaces of bent sections of the first hollow ridges are spaced from crest surfaces of the second hollow ridges. The spaced crest surfaces allow first troughs of the first separator and second troughs of the second separator to communicate with each other, providing communication passages between the first separator and the second separator. Cooling water is passed through the communication passages.

Abstract: A fuel cell includes an electrolyte electrode assembly and a pair of first and second separators. First through fourth oxygen-containing gas holes, first through fourth coolant holes, and first through fourth fuel gas holes extend through the fuel cell. The first through fourth oxygen-containing gas holes are selectively used as an oxygen-containing gas supply port or an oxygen-containing gas discharge port to cause an oxygen-containing gas to flow circularly along an electrode surface in an oxygen-containing gas flow field.

Abstract: A heat medium passage for controlling the temperature of the electric power generation section is separated from the electric power generation section of a fuel cell including a plurality of separators and electric power generating elements alternately laminated in a lamination direction. A heat plate exchanges heat with at least one of the heat medium passage and a heat medium in the heat medium passage and is connected to the separators to provide an electrical conduction between the separators in the lamination direction. An electrical insulator is provided for insulation between the heat medium and the heat plate. Another heat medium passage may be further provided on the other side. A temperature control system for the fuel cell may include a burner for supplying the heated heat medium to the heat medium passage and may comprise first and second fluidic passages independently to selectively use the first and second fluidic passage.

Abstract: A fuel cell stack is formed by stacking a plurality of fuel cells. A heating mechanism is provided for heating an outermost fuel cell by external electrical energy. A power generation circuit including electric heaters corresponding to the fuel cells is provided. Further, a switching mechanism including switches for selectively connecting the fuel cells to the power generation circuit or selectively disconnecting the fuel cells from the power generation circuit is provided.

Abstract: A fuel cell includes cell assemblies connected to each other by a fuel gas connection passage, an oxygen-containing gas connection passage, and a coolant connection passage. A fuel gas adjusting mechanism, an oxygen-containing gas adjusting mechanism, and a coolant adjusting mechanism are connected respectively to the fuel gas connection passage, the oxygen-containing gas connection passage, and the coolant connection passage. These adjusting mechanisms adjust the temperatures in the cell assemblies, the relative humidity in the fuel gas, and the relative humidity in the oxygen-containing gas.

Abstract: A fuel cell includes an electrolyte electrode assembly and a pair of first and second separators. First through fourth oxygen-containing gas holes, first through fourth coolant holes, and first through fourth fuel gas holes extend through the fuel cell. The first through fourth oxygen-containing gas holes are selectively used as an oxygen-containing gas supply port or an oxygen-containing gas discharge port to cause an oxygen-containing gas to flow circularly along an electrode surface in an oxygen-containing gas flow field.

Abstract: A fuel cell includes an electrolyte electrode assembly and a pair of first and second separators. First through fourth oxygen-containing gas holes, first through fourth coolant holes, and first through fourth fuel gas holes extend through the fuel cell. The first through fourth oxygen-containing gas holes are selectively used as oxygen-containing gas supply ports or oxygen-containing gas discharge ports to change the flow direction of an oxygen-containing gas in an oxygen-containing gas flow field continuously.

Abstract: A cell assembly is formed by stacking a first fuel cell and a second fuel cell together. The first fuel cell has a first membrane electrode assembly, and the second fuel cell has a second membrane electrode assembly. In the cell assembly, oxygen-containing gas flow fields of the first and second separators are connected in series, and fuel gas flow fields of the first and second separators are connected in series. Coolant flow fields are formed on opposite sides of the cell assembly, respectively, for supplying a coolant straight in one direction through the coolant flow fields.

Abstract: A first separator of a unit cell and a second separator of another unit cell and are disposed adjacent to each other in a stacked assembly. Crest surfaces of straight sections of first hollow ridges of the first separator are in contact with crest surfaces of second hollow ridges of the second separator, and crest surfaces of bent sections of the first hollow ridges are spaced from crest surfaces of the second hollow ridges. The spaced crest surfaces allow first troughs of the first separator and second troughs of the second separator to communicate with each other, providing communication passages between the first separator and the second separator. Cooling water is passed through the communication passages.

Abstract: A fuel cell separator plate comprising a portion in contact with an electrode, and a sealing portion provided around the contact portion, the contact portion having a larger surface roughness (Rmax) than that of the sealing portion. It is preferably a molded separator plate made of a composite carbon material comprising carbon and a thermosetting resin.