Patent ID: 8367269

Claim:
A separator unit inserted into a proton exchange membrane fuel cell operated at atmospheric pressure and having an electrolyte layer interposed between a fuel electrode and an oxygen electrode, comprising: a plate shaped separator base that separates hydrogen fuel gas supplied to the fuel electrode from oxygen or air oxidizing gas supplied to the oxygen electrode; and a corrugated expanded metal mesh collector provided with thin extending projections and having openings that form one of a passage through which the fuel gas flows and a passage through which the oxidizing gas flows, the collector being provided to at least one side of the separator base in abutment against one of the fuel electrode and the oxygen electrode, wherein: the separator base has coolant passages formed therein, through which a coolant is allowed to flow; an electrode abutment portion of the collector, which abuts against one of the fuel electrode and the oxygen electrode, has an aperture ratio higher than the aperture ratio of a portion other than the electrode abutment portion of the collector; each thin extending projection having a tip portion having a flat surface that abuts against a surface of the plate shaped separator base; and a flat surface of a base portion of the collector between each thin extending projection forms the electrode abutment portion and abuts against an electrode diffusion layer at a side of the fuel electrode or the oxygen electrode; wherein the collector includes a separator abutment portion defined by the flat surface of the tip portion that abuts against the separator base, and a rib portion between the electrode abutment portion and the separator abutment portion, each aperture ratio of which establishes the following relation: aperture ratio of the electrode abutment portion > aperture ratio of the rib portion ≧ aperture ratio of the separator abutment portion; and wherein the thermal resistance of the electrode abutment portion > thermal resistance of the rib portion ≧ thermal resistance of the separator abutment portion, and wherein the electrode abutment, rib, and separator abutment portions of the collector are different materials having respectively different thermal resistances.