Fuel cell stack

Abstract

A casing of a fuel cell stack has stack deformation prevention structure for limiting the change of an interval between end plates on the lower side in a direction of gravity, due to swelling of the lower side of the stack body in the direction of gravity. The stack deformation prevention structure is configured such that elastic modulus of a side plate provided on a lower side of the stack body in the direction of gravity is higher than elastic modulus of a side plate provided on an upper side of the stack body in the direction of gravity.

1 . A fuel cell stack comprising:
 a stack body formed by stacking a plurality of unit cells in a horizontal direction, a pair of end plates sandwiching the stack body, the unit cells each including an electrolyte electrode assembly and separators sandwiching the electrolyte electrode assembly, the electrolyte electrode assembly including a pair of electrodes and an electrolyte interposed between the electrodes; and   stack deformation prevention structure for limiting a change in an interval between the end plates on a lower side of the stack body in a direction of gravity to be not greater than a change in an interval between the end plates on an upper side of the stack body in the direction of gravity due to swelling on the lower side of the stack body in the direction of gravity.   
     
     
         2 . A fuel cell stack according to  claim 1 , wherein the stack deformation prevention structure is configured such that at least the thickness of the electrolyte or the separator on the lower side in the direction of gravity is smaller than the thickness of the electrolyte or the separator on the upper side in the direction of gravity. 
     
     
         3 . A fuel cell stack according to  claim 1 , wherein the stack deformation prevention structure is configured such that at least an interval between the end plates or between insulators adjacent to the end plates on the lower side in the direction of gravity is larger than an interval between the end plates or between the insulators adjacent to the end plates on the upper side in the direction of gravity. 
     
     
         4 . A fuel cell stack according to  claim 1 , wherein the stack deformation prevention structure is configured such that elastic modulus of a seal member of the stack body on the upper side in the direction of gravity is higher than elastic modulus of the seal member on the lower side in the direction of gravity. 
     
     
         5 . A fuel cell stack according to  claim 1 , further comprising a casing containing the stack body, wherein the casing includes a plurality of panel members provided around the stack body; and
 the stack deformation prevention structure is configured such that elastic modulus of the panel member provided on the lower side in the direction of gravity is higher than elastic modulus of the panel member provided on the upper side in the direction of gravity.   
     
     
         6 . A fuel cell stack according to  claim 1 , further comprising a casing containing the stack body,
 wherein the casing includes a plurality of panel members provided around the stack body; and   the stack deformation prevention structure is configured such that, in the panel members provided on lateral sides of the stack body, elastic modulus on the lower side in the direction of gravity is higher than elastic modulus on the upper side in the direction of gravity.   
     
     
         7 . A fuel cell stack according to  claim 6 , wherein the panel members provided on the lateral sides of the stack body each have two upper and lower plate members, and the thickness of the lower plate member is larger than the thickness of the upper plate member. 
     
     
         8 . A fuel cell stack according to  claim 1 , wherein the stack deformation prevention structure is configured such that elastic modulus in the stacking direction of the separators on the lower side in the direction of gravity is smaller than elastic modulus in the stacking direction of the separators on the upper side in the direction of gravity. 
     
     
         9 . A fuel cell stack according to  claim 1 , wherein each of the electrolyte electrode assembly and the separators has a longitudinally elongated shape.