Fuel cell and fuel cell separator

Abstract

A fuel cell is provided with: a membrane electrode assembly (MEA); and a cathode-side separator assembled to the MEA, the cathode-side separator including first passages on a first surface of the cathode-side separator on a side closer to the MEA, and second passages on a second surface of the cathode-side separator on an opposite side, the first and second passages allowing oxidant gas to flow through the first and second passages, respectively. The first passages include first recessed portions on the first surface so as to extend from one end of the cathode-side separator to the other end, the second passages include second recessed portions on the second surface so as to extend from the one end to the other end and to be arranged alternately with the first recessed portions, and a penetration hole on a bottom face of the second recessed portion penetrating through the cathode-side separator

What is claimed is: 
     
         1 . A fuel cell comprising:
 a membrane electrode assembly; and   a cathode-side separator assembled to the membrane electrode assembly, the cathode-side separator including first passages provided on a first surface of the cathode-side separator on a side closer to the membrane electrode assembly, the first passages allowing oxidant gas to flow through the first passages, and second passages provided on a second surface of the cathode-side separator on a side opposite to the membrane electrode assembly across the first surface of the cathode-side separator, the second passages allowing oxidant gas to flow through the second passages, wherein   the first passages include first recessed portions provided on the first surface so as to extend from one end of the cathode-side separator to the other end,   the second passages include second recessed portions provided on the second surface so as to extend from the one end of the cathode-side separator to the other end and to be arranged alternately with the first recessed portions, and   a portion defining a penetration hole penetrating through the cathode-side separator is provided on a bottom face of the second recessed portion constituting the second passage.   
     
     
         2 . The fuel cell according to  claim 1 , wherein
 when a central side region indicates two regions positioned on a central side and end side regions indicate two regions positioned on end sides at a time when the bottom face of the second recessed portion constituting the second passage is equally divided into four regions in a width direction of the second passage so that each of the four regions has a width of ¼ of a width of the second passage, a total area of the portion defining the penetration hole, provided in the central side region, is larger than a total area of the portion defining the penetration hole, provided in the two end side regions.   
     
     
         3 . The fuel cell according to  claim 1 , wherein
 when a central side region indicates two regions positioned on a central side and end side regions indicate two regions positioned on end sides at a time when the bottom face of the second recessed portion constituting the second passage is equally divided into four regions in a width direction of the second passage so that each of the four regions has a width of ¼ of a width of the second passage, the portion defining the penetration hole is provided only in the central side region.   
     
     
         4 . The fuel cell according to  claim 1 , wherein
 when an upstream region indicates a region positioned on an upstream side of a flow of the oxidant gas and a downstream region indicates a region positioned on a downstream side at a time when the bottom face of the second recessed portion constituting the second passage is equally divided into two regions in a lengthwise direction of the second passage so that each of the two regions has a length of ½ of a length of the second passage, a total area of the portion defining the penetration hole, provided in the downstream region, is smaller than a total area of the portion defining the penetration hole, provided in the upstream region.   
     
     
         5 . The fuel cell according to  claim 4 , wherein:
 portions defining a plurality of penetration holes are provided; and   at least one of intervals between the portions defining the penetration holes, provided in the downstream region, is larger than intervals between the portions defining the penetration holes, provided in the upstream region.   
     
     
         6 . The fuel cell according to  claim 4 , wherein:
 portions defining a plurality of penetration holes are provided; and   at least one of areas of the portions defining the penetration holes, provided in the downstream region, is smaller than each of areas of the portions defining the penetration holes, provided in the upstream region.   
     
     
         7 . The fuel cell according to  claim 1 , wherein:
 when an upstream region indicates a region positioned on an upstream side of a flow of the oxidant gas and a downstream region indicates a region positioned on a downstream side at a time when the bottom face of the second recessed portion constituting the second passage is equally divided into two regions in a lengthwise direction of the second passage so that each of the two regions has a length of ½ of a length of the second passage, the portion defining the penetration hole is provided only in the upstream region.   
     
     
         8 . The fuel cell according to  claim 1 , wherein
 a wall portion projecting inwardly in the second passage from the bottom face of the second recessed portion constituting the second passage is provided in an upstream edge among edges of the portion defining the penetration hole, the upstream edge being on an upstream side of a flow of the oxidant gas.   
     
     
         9 . The fuel cell according to  claim 8 , wherein:
 portions defining a plurality of penetration holes are provided; and   the portion defining the penetration hole and provided with the wall portion is provided on a downstream side of the second passage relative to the portion defining the penetration hole and not provided with the wall portion.   
     
     
         10 . The fuel cell according to  claim 8 , wherein:
 portions defining a plurality of penetration holes are provided; and   heights of the wall portions provided in the portions defining the plurality of penetration holes are set such that the height of the wall portion on a downstream side of the second passage is higher than the height of the wall portion on the upstream side of the second passage.   
     
     
         11 . The fuel cell according to  claim 8 , wherein
 the wall portion is provided in the upstream edge among the edges of the portion defining the penetration hole, and in a lateral edge among the edges of the portion defining the penetration holes, the lateral edge being along the flow of the oxidant gas.   
     
     
         12 . The fuel cell according to  claim 1 , wherein
 a part where the portion defining the penetration hole is provided on the bottom face of the second recessed portion projects more than the other part of the bottom face of the second recessed portion.   
     
     
         13 . The fuel cell according to  claim 1 , wherein
 a width of a part of the second passage in which the portion defining the penetration hole is provided is wider than a width of a part of the second passage in which the portion defining the penetration hole is not provided.   
     
     
         14 . A fuel cell separator to be assembled to a membrane electrode assembly, the fuel cell separator comprising:
 first recessed portions provided on one surface so as to extend from one end of the fuel cell separator to the other end;   second recessed portions provided on the other surface so as to extend from the one end of the fuel cell separator to the other end and to be arranged alternately with the first recessed portions, the second recessed portions each having a bottom face provided with a portion defining a penetration hole penetrating through the fuel cell separator.