JP2010212149A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure sealing property of a sealing member with a simple and easy constitution in a fuel cell stack and apply a larger load to a power generation element than that applied to the sealing member. <P>SOLUTION: End plates 20a, 20b are arranged at both ends respectively in a stacking direction of a stack 10L in which a plurality of single cells are stacked, and by fastening these by fastening sticks 30 and nuts 32, the fuel cell stack 100 is composed in which the dimension in the stacking direction of the plurality of single cells is regulated in a fixed measurement. When the end plates 20a, 20b are fastened, a shim 40 having a nearly similar outside shape appearance with that of the power generation element 10a is inserted into a portion that is between the end of the stack 10L and the end plate 20b and opposing to the power generation element 10a equipped by the single cell 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell stack.

  A fuel cell that generates power by an electrochemical reaction between a fuel gas and an oxidant gas has attracted attention as an energy source. This fuel cell is generally used in the form of a fuel cell stack including a laminate in which a plurality of single cells are laminated. In this fuel cell stack, each single cell has a seal for preventing leakage of fluid (fuel gas, oxidant gas, cooling water) flowing in the fuel cell stack at the peripheral portion of the power generator including the membrane electrode assembly. The members are arranged and sandwiched by separators. In such a fuel cell stack, generally, a fastening load is applied in the stacking direction of the single cells in order to ensure the sealing performance of the sealing member or reduce the contact resistance between the power generator and the separator, Fastened by the fastening member.

  By the way, in the fuel cell stack, the load required to ensure the sealing performance of the seal member may differ from the load required to reduce the contact resistance between the power generator and the separator. Therefore, for example, in Patent Document 1 below, a fuel cell (fuel) including a fastening load application mechanism that applies different fastening loads to a power generation unit (power generation unit) and a seal unit (seal member) in a stack of a plurality of single cells. Battery stacks) have been proposed.

JP 2006-179402 A JP 2007-59187 A

  However, the technique described in Patent Document 1 is intended to fasten a single-cell laminate so that an excessive load is not applied to the power generation unit while ensuring good sealing performance at the seal unit. In order to reduce the contact resistance between the power generation body and the separator, no consideration has been given to applying a load larger than the load applied to the seal portion to the power generation portion. In addition, the structure of the fuel cell stack was relatively complicated.

  The present invention has been made to solve the above-described problems, and in a fuel cell stack, the seal member has a relatively simple configuration and ensures the sealing performance of the seal member, and more than the load applied to the seal member. The purpose is to apply a large load to the generator.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 In a fuel cell stack, a seal member is disposed at a peripheral portion of a power generator that generates power by an electrochemical reaction between a fuel gas and an oxidant gas, and the power generator and the seal member are separated by a separator. A laminated body in which a plurality of unit cells are sandwiched and laminated, a pair of end plates respectively disposed at both ends of the laminated body in the lamination direction of the single cells, and substantially the same outer shape as the power generator A shim disposed between at least one of both end portions of the laminated body and the end plate and facing the power generation body, and the laminated body between the pair of end plates In addition, by pressing the pair of end plates with the shim sandwiched therebetween, a pressing force is applied to the stacked body in the stacking direction, and the pair of end plates Fuel cell stack comprising fastening a member, a for defining the distance between the end plates fixed dimensions.

  In the fuel cell stack of Application Example 1, the pair of end plates are fastened using the fastening member to apply a pressing force to the stacked body in the stacking direction of the single cells, and between the end plates. When the distance is set to a predetermined dimension and fastened, an appropriate load is applied to the seal member, and the sealing performance of the seal member can be ensured. In addition, the magnitude | size of the load applied with respect to the said sealing member can be suitably changed suitably, for example by changing the material and thickness of the said sealing member, and the thickness of the said separator.

  Furthermore, in the fuel cell stack of Application Example 1, between at least one of both end portions of the stacked body in the stacking direction of the single cells and the end plate, the portion facing the power generator, Since the shim having substantially the same outer shape as the power generation body is disposed, a load larger than the load applied to the seal member can be appropriately applied to the power generation body relatively easily. In addition, the magnitude | size of the load added with respect to the said electric power generation body can be suitably changed suitably, for example by changing the thickness of the said shim.

  That is, according to the fuel cell stack of Application Example 1, with a relatively simple configuration, it is possible to ensure the sealing performance of the seal member and to apply a load larger than the load applied to the seal member to the power generator.

It is explanatory drawing which shows schematic structure and the manufacturing method of the fuel cell stack 100 as one Example of this invention.

Hereinafter, embodiments of the present invention will be described based on examples.
FIG. 1 is an explanatory diagram showing a schematic configuration and a manufacturing method of a fuel cell stack 100 as one embodiment of the present invention. In FIG. 1, a side view of the fuel cell stack 100 is shown together with a cross-sectional view of the single cells 10 constituting the fuel cell stack 100.

  The fuel cell stack 100 includes a stacked body 10L in which a plurality of single cells 10 are stacked. Each single cell 10 includes a power generator 10a including a membrane electrode assembly formed by bonding an anode and a cathode to both surfaces of an electrolyte membrane having proton conductivity. And each single cell 10 is comprised by arrange | positioning the sealing member 10b in the peripheral part of the electric power generation body 10a, and pinching these with the separator 10c. In this example, a solid polymer membrane was used as the electrolyte membrane. Further, a silicone rubber having gas impermeability, elasticity, and heat resistance is used as the seal member 10b. Further, as the separator 10c, a metal separator having conductivity and flexibility is used. The number of membrane electrode assemblies stacked in the fuel cell stack 100 can be arbitrarily set according to the output required for the fuel cell stack 100.

  In the fuel cell stack 100, the end plates 20a and 20b are arranged at both ends of the stacked body 10L in the stacking direction of the single cells 10 and fastened using the fastening rod 30 and the nut 32. Composed. The fastening rod 30 and the nut 32 correspond to the fastening member in the present invention. Then, by pressing the end plate 20a and the end plate 20b, a pressing force is applied to the stacked body 10L in the stacking direction of the single cells 10. Each end plate 20a, 20b is formed of a metal such as steel in order to ensure rigidity. In addition, a current collector plate and an insulating plate (not shown) are interposed between the laminate 10L and the end plate 20a and between the laminate 10L and the end plate 20b, respectively. Each current collecting plate is provided with an output terminal, and the power generated by the fuel cell stack 100 can be output from these output terminals.

  In the fuel cell stack 100, the end plates 20a, 20b and the fastening rods 30 are, for example, rod-shaped in the fastening rods 30 in the through holes 20h formed in the thickness direction at the four corners of the end plates 20a, 20b. The male screw part 30b formed at both ends of the part 30a is inserted, and a nut 32 having an internal thread formed on the inner wall is screwed into the male screw part 30b. In addition, the thickness of the rod-shaped portion 30a in the fastening rod 30 is set to be larger than the size of each through hole 20h formed in each end plate 20a, 20b, and in the stacking direction of the single cells 10 in the fuel cell stack 100. The length is defined by the length of the rod-shaped portion 30a regardless of the magnitude of the fastening load applied to the laminate 10L.

  In general, in a fuel cell stack, a fastening structure for fastening a plurality of single cells 10 is a length in the stacking direction of the single cells 10 in the fuel cell stack 100 by a fastening rod 30 as in the fuel cell stack 100 of the present embodiment. There are known so-called fixed-size fuel cell stacks, and so-called constant-load structure fuel cell stacks in which a constant load is applied to the laminate 10L using a spring or the like. In the fuel cell stack with the constant load structure, for example, since the constant load is continuously applied to the single cell 10 as compared with the fuel cell stack with the fixed size structure, the creep of each part in the single cell 10 is likely to proceed. There is a disadvantage that a space for arranging the fuel cell stack is necessary, and the size of the fuel cell stack tends to be large. For this reason, in the fuel cell stack 100 of the present embodiment, the fixed-size structure described above is eliminated by adopting a fixed-size structure as the fastening structure of the plurality of single cells 10.

  Hereinafter, an example of the manufacturing process of the fuel cell stack 100 will be described. First, fastening bars 30 for fastening the laminated body 10L are fixed to the four corners of the end plate 20a having a rectangular shape (see the upper part of FIG. 1). Next, a predetermined number of single cells 10 are stacked on the end plate 20a to form a stacked body 10L. Although not shown, each single cell 10 has a substantially rectangular shape with notches formed at the four corners, and each notch is brought into contact with the fastening rod 30. Thus, the stacked body 10L is positioned on the end plate 20a. Next, the other male screw portion 30b of each fastening rod 30 is inserted into each through-hole 20h formed in the end plate 20b and fixed by the nut 32, so that the single cells 10 in the stacked body 10L are stacked in the stacking direction. A fastening load is applied.

  At this time, a shim 40 having substantially the same outer shape as that of the power generation body 10a is provided between the stacked body 10L and the end plate 20b and in a portion facing each of the power generation bodies 10a in each unit cell 10 constituting the stack 10L. The end plate 20b is fixed in a state in which is placed. By sandwiching the shim 40 between the laminated body 10L and the end plate 20b, each single cell 10 is bent by the elasticity of the seal member 10b and the flexibility of the separator 10c, and the power generator in each single cell 10 The area where 10a is arranged is pressed (see the lower part of FIG. 1). In the fuel cell stack 100 of the present embodiment, a fitting recess 20bd into which the shim 40 is fitted is formed on the surface of the end plate 20b facing the stacked body 10L, and the fitting recess 20bd Positioning and displacement of the shim 40 can be prevented.

  According to the fuel cell stack 100 of the present embodiment described above, the end plates 20a and 20b are fastened using the fastening rod 30 and the nut 32, thereby pushing the stacked body 10L in the stacking direction of the single cells 10. An appropriate load can be applied to the seal member and the sealing performance of the seal member can be ensured by applying a pressure and fastening the end plate 20a, 20b with a predetermined distance. In addition, the magnitude | size of the load added with respect to the sealing member 10b is possible by designing appropriately the material and thickness of the sealing member 10b, and the thickness of the separator 10c, for example.

  Further, according to the fuel cell stack 100 of the present embodiment, the shim 40 is located between the end of the stacked body 10L in the stacking direction of the single cells 10 and the end plate 20b and facing the power generator 10a. Since it is interposed, a load larger than the load applied to the seal member 10b can be appropriately applied to the power generation body 10a. In addition, the magnitude | size of the load added with respect to the electric power generation body 10a is possible by designing the thickness of the shim 40 appropriately, for example.

  That is, according to the fuel cell stack 100 of the present embodiment, the sealing performance of the seal member 10b is ensured with a relatively simple configuration, and a load larger than the load applied to the seal member 10b is applied to the power generator 10a. Can do.

  In this embodiment, the shim 40 is interposed between the laminated body 10L and the end plate 20b. However, the shim 40 is also interposed between the laminated body 10L and the end plate 20a. It may be. That is, you may make it interpose the shim 40 in the both ends of the laminated body 10L about the lamination direction of the single cell 10. FIG. By doing so, compared to the case where the shim 40 is interposed at one end of the laminate 10L, the amount of bending of the separator 10c when a load is applied to the power generation body 10a is reduced by half, and the creep of the separator 10c is reduced. Can be suppressed.

DESCRIPTION OF SYMBOLS 100 ... Fuel cell stack 10 ... Single cell 10L ... Laminated body 10a ... Electric power generation body 10b ... Sealing member 10c ... Separator 20a, 20b ... End plate 20h ... Through-hole 20bd ... Fitting recessed part 30 ... Fastening rod 30a ... Shaft part 30b ... Male Screw part 32 ... Nut 40 ... Shim

Claims (1)

A fuel cell stack,
A seal member is disposed at a peripheral portion of a power generator that generates power by an electrochemical reaction between a fuel gas and an oxidant gas, and a plurality of single cells configured by sandwiching the power generator and the seal member with a separator are stacked. A laminate,
A pair of end plates respectively disposed at both ends of the stacked body in the stacking direction of the single cells;
A shim that has substantially the same outer shape as the power generation body, is disposed between at least one of both end portions of the laminate and the end plate, and is disposed at a portion facing the power generation body;
By fastening the pair of end plates in a state where the laminate and the shim are sandwiched between the pair of end plates, a pressing force is applied to the laminate in the stacking direction, and the pair of end plates A fastening member for defining the distance between the end plates to a certain dimension;
A fuel cell stack comprising:

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