Method and apparatus for providing a uniform fuel cell stack structure
An electro-chemical fuel cell stack has a plurality of fuel cells arranged in a stacked configuration to form a fuel cell assembly. The fuel cell assembly is interposed between at least one spacer plate and first and second end plates. The first and second end plates are held in a fixed spaced relation so that the first and second end plates impart a compressive force on the fuel cell assembly. The spacer plates can be used to provide a fuel cell stack of a predetermined length. The fuel cell stack can be made by compressing the fuel cell stack with a predetermined compressive load or by compressing the fuel cell stack a predetermined distance and then securing the first and second end plates in a fixed spaced relation.
1. A method of making an electro-chemical fuel cell stack of a predetermined length, the method comprising the steps of:
choosing a predetermined length for a fuel cell stack having a fuel cell assembly;
compressing said fuel cell assembly with a predetermined compressive load;
determining a compressed length of said compressed fuel cell assembly;
calculating a difference between a length of space available for said compressed fuel cell assembly in said fuel cell stack and said compressed length of said compressed fuel cell assembly;
removing said predetermined compressive load from said fuel cell assembly;
positioning at least one spacer plate having a thickness generally equal to said calculated difference in said fuel cell stack;
applying a compressive load to said fuel cell stack so that said fuel cell stack is compressed to said predetermined length;
securing first and second end plates of said fuel cell stack in a fixed spaced relation to retain said fuel cell stack at said predetermined length, thereby imparting a compressive force on said fuel cell assembly after said applied compressive load on said fuel cell stack is removed; and
removing said applied compressive load from said fuel cell stack.
2. The method of claim 1 , wherein the step of determining a compressed length of said compressed fuel cell assembly includes measuring said compressed length of said compressed fuel cell assembly.
3. The method of claim 1 , wherein the step of compressing said fuel cell assembly includes compressing said fuel cell stack with said predetermined compressive load.
4. The method of claim 3 , wherein the step of determining a compressed length of said compressed fuel cell assembly includes measuring said compressed length of said compressed fuel cell assembly.
5. The method of claim 3 , wherein the step of determining a compressed length of said compressed fuel cell assembly includes measuring a length of said compressed fuel cell stack and calculating said compressed length of said fuel cell assembly.
6. The method of claim 1 , wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a dry end of said fuel cell assembly and an end plate adjacent said dry end of said fuel cell assembly.
7. The method of claim 1 , wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a terminal plate adjacent at least one of first and second end plates and said fuel cell assembly.
8. The method of claim 1 , wherein the step of securing first and second end plates of said fuel cell stack in a fixed spaced relation includes attaching at least one side plate to said first and second end plates of said fuel cell stack.
9. A method of making an electro-chemical fuel cell stack of a predetermined length, the method comprising the steps of:
choosing a predetermined length for a fuel cell stack having a fuel cell assembly;
compressing said fuel cell stack with a predetermined compressive load;
determining a compressed length of said compressed fuel cell stack;
calculating a difference between said predetermined length and said compressed length of said compressed fuel cell stack;
removing said predetermined compressive load from said fuel cell stack;
positioning at least one spacer plate having a thickness generally equal to said calculated difference in said fuel cell stack;
applying a compressive load to said fuel cell stack so that said fuel cell stack is compressed to said predetermined length;
securing first and second end plates of said fuel cell stack in a fixed spaced relation to retain said fuel cell stack at said predetermined length, thereby imparting a compressive force on said fuel cell assembly after said applied compressive load on said fuel cell stack is removed; and
removing said applied compressive load from said fuel cell stack.
10. The method of claim 9 , wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a dry end of said fuel cell assembly and an end plate adjacent said dry end of said fuel cell assembly.
11. The method of claim 9 , wherein the step of positioning at least one spacer plate includes positioning said at least one spacer plate between a terminal plate adjacent at least one of said first and second end plates and said fuel cell assembly.
12. The method of claim 9 , wherein the step of securing first and second end plates of said fuel cell stack in a fixed spaced relation includes attaching at least one side plate to said first and second end plates of said fuel cell stack.