Abstract: A fuel cell system includes a fuel cell stack, an oxygen-containing gas supply apparatus, a fuel gas supply apparatus, a pressure reduction apparatus, and a dilution apparatus. The oxygen-containing gas supply apparatus supplies an oxygen-containing gas to the fuel cell stack. The oxygen-containing gas supply apparatus is capable of supplying the air to the fuel gas flow field at the time of stopping operation of the fuel cell system. The fuel gas supply apparatus supplies a fuel gas to the fuel cell stack. The pressure reduction apparatus suctions gases in the oxygen-containing gas flow field and the fuel gas flow field. The dilution apparatus dilutes the fuel gas suctioned by the pressure reduction apparatus using the air.

Abstract: A fuel cell includes a membrane electrode assembly and first and second metal plates sandwiching the membrane electrode assembly. The first metal plate has positioning ribs for positioning the outer region of the membrane electrode assembly. The first and second metal plates are positioned in alignment with each other by the first and second insulating bushings attached to first and second positioning holes of the first and second metal plates. Further, the first and second metal plates sandwiching the membrane electrode assembly are fastened together by a plurality of metal clip members.

Abstract: A fuel cell includes a membrane electrode assembly, and first and second separators. A first insulating bushing is attached to a first positioning hole of a first separator, and a second insulating bushing is attached to a second positioning hole of the second separator. An inner wall of the first insulating bushing is fitted to an outer wall of the second insulating bushing for positioning the first and second separators such that the first and second separators are insulated from each other.

Abstract: A fuel cell stack has fuel cell units. Each of the fuel cell units includes first and second membrane electrode assemblies and first to third separators sandwiching the first and second membrane electrode assemblies. A positioning mechanism is used for positioning the first to third separators in alignment with each other. The positioning mechanism includes a first protruded portion and a second protruded portion. The first protruded portion protrudes from one surface of the second separator for positioning the first separator. The second protruded portion protrudes from the other surface of the second separator for positioning the third separator.

Abstract: A seal member is formed integrally on surfaces of a metal separator of a fuel cell. The seal member includes an outer seal and an inner seal provided on a surface of the metal separator. A plurality of closure seals are formed integrally with an inner edge of the inner seal. The closure seals close a space between the inner seal and a protrusion forming a fuel gas flow field.

Abstract: A fuel cell has a unit cell in which a membrane electrode assembly, in which a pair of electrodes are provided on either side of an electrolyte membrane, is provided between a first separator and a second separator. Pin insertion holes are respectively provided in a plurality of portions in an outer periphery of each of the first and the second separators, and the pin insertion holes of the first separators are respectively coaxial with those of the second separator. A leg portion of a cell fastening pin made of resin is inserted through each pair of the coaxial pin insertion holes of the first and the second separators. The unit cell is fastened by fitting a flange portion formed at an end of the leg portion to the first separator, and fitting a hook portion formed at the other end of the leg portion to the second separator.

Abstract: A fuel cell system includes a fuel cell stack, an oxygen-containing gas supply apparatus, a fuel gas supply apparatus, a pressure reduction apparatus, and a dilution apparatus. The oxygen-containing gas supply apparatus supplies an oxygen-containing gas to the fuel cell stack. The oxygen-containing gas supply apparatus is capable of supplying the air to the fuel gas flow field at the time of stopping operation of the fuel cell system. The fuel gas supply apparatus supplies a fuel gas to the fuel cell stack. The pressure reduction apparatus suctions gases in the oxygen-containing gas flow field and the fuel gas flow field. The dilution apparatus dilutes the fuel gas suctioned by the pressure reduction apparatus using the air.

Abstract: A fuel cell includes a membrane electrode assembly, and first and second separators. A first insulating bushing is attached to a first positioning hole of a first separator, and a second insulating bushing is attached to a second positioning hole of the second separator. An inner wall of the first insulating bushing is fitted to an outer wall of the second insulating bushing for positioning the first and second separators such that the first and second separators are insulated from each other.

Abstract: A fuel cell includes a membrane electrode assembly, and first and second separators. A first insulating bushing is attached to a first positioning hole of a first separator, and a second insulating bushing is attached to a second positioning hole of the second separator. An inner wall of the first insulating bushing is fitted to an outer wall of the second insulating bushing for positioning the first and second separators such that the first and second separators are insulated from each other.

Abstract: A fuel cell includes a plurality of metal clip members for holding outer regions of first and second metal separators at a plurality of positions. Each of the metal clip member includes a side plate and first and second holding portions. The side plate is curved at opposite ends, and the first and second holding portions are extending from the opposite ends of the side plate. The first and second holding portions generates a predetermined elastic force for holding the first and second metal separators. The outer ends of the first and second metal separators are covered by insulating sections, and the insulating sections are held between the first and second holding portions so that the entire unit cell is tightened by the predetermined elastic force.

Abstract: A fuel cell has a unit cell in which a membrane electrode assembly, in which a pair of electrodes are provided on either side of an electrolyte membrane, is provided between a first separator and a second separator. Pin insertion holes are respectively provided in a plurality of portions in an outer periphery of each of the first and the second separators, and the pin insertion holes of the first separators are respectively coaxial with those of the second separator. A leg portion of a cell fastening pin made of resin is inserted through each pair of the coaxial pin insertion holes of the first and the second separators. The unit cell is fastened by fitting a flange portion formed at an end of the leg portion to the first separator, and fitting a hook portion formed at the other end of the leg portion to the second separator.

Abstract: A fuel cell stack has fuel cell units. Each of the fuel cell units includes first and second membrane electrode assemblies and first to third separators sandwiching the first and second membrane electrode assemblies. A positioning mechanism is used for positioning the first to third separators in alignment with each other. The positioning mechanism includes a first protruded portion and a second protruded portion. The first protruded portion protrudes from one surface of the second separator for positioning the first separator. The second protruded portion protrudes from the other surface of the second separator for positioning the third separator.

Abstract: A fuel cell includes a membrane electrode assembly and first and second metal plates sandwiching the membrane electrode assembly. The first metal plate has positioning ribs for positioning the outer region of the membrane electrode assembly. The first and second metal plates are positioned in alignment with each other by the first and second insulating bushings attached to first and second positioning holes of the first and second metal plates. Further, the first and second metal plates sandwiching the membrane electrode assembly are fastened together by a plurality of metal clip members.

Abstract: A seal member is formed integrally on surfaces of a metal separator of a fuel cell. The seal member includes an outer seal and an inner seal provided on a surface of the metal separator. A plurality of closure seals are formed integrally with an inner edge of the inner seal. The closure seals close a space between the inner seal and a protrusion forming a fuel gas flow field.

Abstract: A fuel cell includes a membrane electrode assembly, and first and second separators. A first insulating bushing is attached to a first positioning hole of a first separator, and a second insulating bushing is attached to a second positioning hole of the second separator. An inner wall of the first insulating bushing is fitted to an outer wall of the second insulating bushing for positioning the first and second separators such that the first and second separators are insulated from each other.

Abstract: A fuel cell includes a plurality of metal clip members for holding outer regions of first and second metal separators at a plurality of positions. Each of the metal clip member includes a side plate and first and second holding portions. The side plate is curved at opposite ends, and the first and second holding portions are extending from the opposite ends of the side plate. The first and second holding portions generates a predetermined elastic force for holding the first and second metal separators. The outer ends of the first and second metal separators are covered by insulating sections, and the insulating sections are held between the first and second holding portions so that the entire unit cell is tightened by the predetermined elastic force.