JP2004179057A - Tightening structure of solid polymer fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a tightening structure of a solid polymer fuel cell stack with high reliability and excellent power generating efficiency by applying a uniform compression load within a plane in a simple structure on a stack laminated with cells. <P>SOLUTION: A pair each of collector plates 21, insulators 23, end plates 24, and, at an outermost side, tie plates 25 divided into two at one side are arranged in that order toward outside with a stack part 20 laminating the cells at the center, which are tightened with a tie rod fitted between the pair of the tie plates 25, and are integrated in a state with the compression load applied. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell, and more particularly, to a fastening structure of a polymer electrolyte fuel cell stack in which cells are stacked.
[0002]
[Prior art]
FIG. 1 (refer to FIG. 1 of Patent Document 1) shows a conventional fuel cell fastening device for fastening a stack in which cells are stacked. This is because the pressing plates 35a and 35b provided with the curved surface portions 38a are arranged on both sides of the stack 31 such that the curved surface portions 38a face the opposite direction of the molten salt type stack 31, and the curved surface portions 38a are further pressed to the pressing plate 35a. , 35b, the pressurizing beams 32a, 32b are arranged above the curved surface portion 38a, and are further tightened by the tightening rods 33 penetrating both sides of the pressurized beams 32a, 32b. The stack 31 is pressurized and fixed (for example, see Patent Document 1).
[0003]
As shown in FIG. 2 (refer to FIG. 1 of Patent Document 2), a flat solid electrolyte fuel cell in which unit cells 1 and spacers 3 interposed between separators 2 are alternately stacked. In a device for applying a compressive load in the stacking direction, a lower mount 5 on which the fuel cell is mounted, a sphere 10 mounted on the lower mount 5 at substantially the center of the uppermost surface of the fuel cell, and a lower base 5 mounted on the sphere 10 In some cases, a compression load in the stacking direction is applied to the fuel cell sandwiched between the upper pedestal 6 and the lower pedestal 5 and the upper pedestal 6 by bringing the lower pedestal 5 and the upper pedestal 6 closer (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-9-259916 (page 3, FIG. 1)
[Patent Document 2]
JP-A-9-139223 (Page 3, FIG. 1)
[0005]
[Problems to be solved by the invention]
In the fuel cell tightening device of Patent Document 1 (Japanese Patent Application Laid-Open No. 9-259916), tightening rods provided at both ends of a pair of pressurizing beams 32a and 32b provided with the stack 31 interposed therebetween. Looking at the positional relationship between the through hole 33 and the curved portions 38a provided on the pressing plates 35a and 35b pressurized by the pair of pressure beams, respectively, the direction connecting the through holes of the tightening rod and the curved surface are shown. The directions connecting the portions 38a are provided to be the same. In this case, if there is a difference in the tightening pressure by the tightening rods at both ends of the pair of pressurizing beams 32a and 32b, the load applied to the curved surface portion 38a will be unbalanced, and the direction of the tightening rod with the higher tightening pressure will be lost. The movement of the load occurs on a certain curved surface portion 38a, and the distribution of the in-plane contact pressure on the contact surface between the cells constituting the stack 31 becomes non-uniform. As a result, generation of electricity due to leakage of reaction gas and cooling water generated between cells, mechanical damage of cells caused by stress and strain, and power transmission loss between cells due to increase in contact resistance generated at parts where the contact pressure between cells is low. Problems such as reduced efficiency may occur.
[0006]
Further, in the flat solid electrolyte fuel cell disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 9-139223), a fuel cell in which unit cells 1 and spacers 3 interposed between separators 2 are alternately stacked is provided with a fuel. A compressive load is applied to the lower base 5 and the sphere 10 arranged at both ends of the battery in the stacking direction. In this state, the load by the sphere 10 is applied as a point load near the center of the outermost separator 2 of the fuel cell, and the separator 2 receiving the point load applies the point load uniformly in the stacking direction of the unit cells 1. In order to transmit the surface load as a distributed surface load, it is necessary for the separator 2 that has received the point load to distribute the point load within the separator 2 so as to have a uniform distribution of the surface load. For that purpose, a robust separator 2 that takes into account a material, a shape, and the like that does not deform even when subjected to a point load is required, and as a result, there is an unavoidable problem that the weight and size of the fuel cell must be increased. As a means for realizing a fuel cell having a large capacity, there is a method of increasing the area of the stacked unit cells 1, but in order to secure a constant load per unit area, the area of the unit cell 1 is increased. Accordingly, an increase in load due to the sphere 10 and a further robust separator 2 are required. Therefore, as the capacity of the fuel cell increases, the weight and the size of the fuel cell increase synergistically. Further, if the capacity is further increased, it may be difficult to secure a uniform load of the surface load. In such a case, Patent Document 1 (Japanese Patent Application Laid-Open No. 9-259916) is described. There is no denying that problems may arise.
The present invention has been made in view of the above problems, and has a small, lightweight, high-quality, low-cost, solid polymer fuel cell that has improved power generation efficiency by reducing power transfer loss between cells. To provide.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is directed to a cell stack in which cells are stacked, end plates arranged on both sides of the cell stack in the stacking direction, A tie plate that is disposed on the opposite side of the cell stack with the plate interposed therebetween and applies a compressive load in the stacking direction via the end plate, wherein the tie plate is provided on one side of the cell stack in the stacking direction. It is characterized in that a plurality are provided and provided symmetrically at positions symmetrical with respect to the cell laminate.
[0008]
The invention described in claim 2 of the present invention is directed to the tie plate according to claim 1, wherein the tie plate has a longitudinal direction of a cut surface obtained by cutting the cell laminate at a plane orthogonal to a laminating direction of the cell laminate. The present invention is characterized in that a load point is provided on the center line.
[0009]
According to a third aspect of the present invention, in the first or second aspect, the tie plate is provided with a through-hole for passing a tie rod on a center line in a direction orthogonal to a linear direction connecting the load points. It is characterized by having been done.
[0010]
According to a fourth aspect of the present invention, in the first to third aspects, the tie plate is provided with two load points.
[0011]
Furthermore, in the invention described in claim 5 of the present invention, in claim 1 to 4, the number of the tie plates arranged on one side is equal to or less than the total number of load points provided on the tie plate arranged on one side. It is characterized by being.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. The embodiments are not limited to these embodiments unless otherwise described.
[0013]
FIG. 3 is an exploded perspective view showing an embodiment of a fastening structure of a polymer electrolyte fuel cell stack according to the present invention, and FIG. 4 is an assembled perspective view. FIG. 3 will be described here. In the stack module 30 of the polymer electrolyte fuel cell according to this embodiment, the center polymer electrolyte membrane (not shown) is sandwiched between the fuel electrode serving as the catalyst electrode and the air electrode from both sides, and the collection A porous support layer is provided as an electric material, and a separator provided with a supply path for a reaction gas of hydrogen or oxygen is disposed outside the support layer, and a cell is configured integrally. A pair of current collector plates 21 for taking out the electricity generated by the stack unit 20 to the outside sequentially from the stack unit 20 in which the cells having the above-described configuration are centered, and securing electrical insulation. 23, an end plate 24 for applying an in-plane uniform compressive load to the stack portion 20, and two tie plates 25 on one side for applying a load to the end plate 24 on the outermost side. Have been. Then, through holes 71 are provided at both ends of a pair of tie plates 25 symmetrically arranged at symmetric positions with respect to the stack portion 20 of each of the two tie plates 25, and screw portions 26 are provided at both ends. By tying both ends of the tie rods 27 connected between a pair of tie plates and fastening them with nuts 28 from the outside, the stack portion 20, the current collecting plate 21, the insulator 23, the end plate 24, and the tie plate 25 are formed. It is integrated under a state where a compressive load is applied.
[0014]
Here, the tie plate 25 and the end plate 24 will be described in detail. The tie plate 25 is disposed on the outermost side of the stack module 30 and serves to hold a load to be applied to the end plate 24, transmits the held load to the end plate 24, and The part 20 is provided with a function of applying pressure as a surface load having a uniform distribution. The latter function is as follows. A load point 29 is provided in the direction of the stack portion 20 of the tie plate 25 on the center line in the longitudinal direction of a cut surface obtained by cutting the stack portion 20 along a plane perpendicular to the cell stacking direction of the stack portion 20. By applying a load to the end plate 24 at the point 29, the stack portion 20 is applied as a surface compressive load. As shown in FIG. 5, the point load is applied to a screw hole 60 provided at the position of the load point of the tie plate 25 by screwing a screw 61 from the opposite direction of the stack portion toward the stack portion. The collar 63 is inserted into the screw portion 62 protruding in the direction of the stack portion 20 of the 25, and the disc spring 64 is inserted from above. A guide hole 70 is provided on the tie plate side surface of the end plate 24 at a position corresponding to the load point 29 of the tie plate 25. The load is transmitted to the end plate 24 via a disc spring 64 attached to the screw portion 62 by inserting the guide hole 70 into the guide hole 70 provided in the plate 24 and applying a load. On the other hand, the former function, as described above, penetrates through both ends of a pair of tie plates 25 symmetrically arranged at symmetric positions with respect to the stack portion 20 of the two tie plates 25 arranged on one side. A hole 71 is provided, and both ends of a tie rod 27 provided with a thread portion 26 at both ends are connected and penetrated between both tie plates 25 and fastened with nuts 28 from the outside. The direction connecting the two through holes 71 provided on both end surfaces of the tie plate 25 is provided on the center line in the direction orthogonal to the direction connecting the load points 29 of the tie plate as shown in FIG.
[0015]
【The invention's effect】
As described above, the fastening structure of the polymer electrolyte fuel cell stack of the present invention has a configuration in which a tie plate for applying a compressive load to a stack portion in which cells are stacked is divided into a plurality of pieces on one side. As a result, the required compressive load is distributed to the divided tie plates, and the load required for one tie plate can be reduced. Therefore, the degree of stiffness required for the tie plate is reduced, and the size of the stack module can be reduced. This contributes to weight reduction.
[0016]
Further, by dividing the tie plate, the size of one tie plate can be reduced, and the tolerance during manufacturing can be set to be small. Therefore, the assembling accuracy of the product is improved, and a product having constant quality and performance can be manufactured with good reproducibility.
[0017]
In addition, even if there is a mounting error in the spring or tie plate that becomes the point load of one tie plate due to the division of the tie plate, adjust it with another tie plate and compensate to ensure an even load. As a result, it is possible to design and manufacture with a margin.
[0018]
Also, when a plurality of products having different dimensions are to be made into a series and a product lineup is to be achieved, if a single tie plate is used, the tie plate must be designed and manufactured for each product. On the other hand, since the tie plate is divided into smaller parts due to its division, it can be used as a common part although there are some restrictions on design conditions, leading to a reduction in design man-hours and a reduction in cost due to mass production.
[0019]
In addition, the adjustment of the compressive load is performed at two places per one tie plate, so that the adjustment is easy, and at the same time, the surface distortion caused by poor adjustment that occurs when the load adjustment at three or more places is required with one tie plate. Can prevent cell damage.
[0020]
Also, a guide hole is provided at the position corresponding to the load point of the tie plate on the tie plate side surface of the end plate, and the threaded part protruding from the load point of the tie plate is inserted into the guide hole provided on the end plate. By applying the load of the rate, the load point of the tie plate can be easily and accurately adjusted to the determined position of the end plate. Therefore, the assembling efficiency is improved, which leads to a reduction in cost.
[0021]
In addition, a load point is provided on the center line in the longitudinal direction of the cut surface obtained by cutting the stack portion in a direction perpendicular to the cell stacking direction of the stack portion, and a load is applied to the end plate at this load point. Therefore, even if the balance of the tightening force of the tie rods provided in a direction perpendicular to the direction connecting the load points is slightly distorted, the load points do not move in the direction connecting the load points, and the tie rods are tightened. The movement of the load in the direction is also extremely small as compared with the difference in the tightening force of the tie rods. Therefore, the tightening adjustment of the tie rod is easy, and the distribution of the contact pressure in the contact surface between the cells becomes non-uniform. High reliability, good power generation efficiency, and no problems such as mechanical breakage of the cells and a decrease in power generation efficiency due to loss of power transfer between cells due to an increase in contact resistance caused by the low contact pressure between cells In addition to ensuring high performance, in large-scale production, it is extremely effective in reducing manufacturing costs by simple load adjustment and reducing variations in performance, making it possible to manufacture reproducible products. .
[Brief description of the drawings]
FIG. 1 is described as FIG. 1 in Reference Document 1 (Japanese Patent Application Laid-Open No. 9-259916).
FIG. 2 is described as FIG. 1 in Reference 2 (Japanese Patent Laid-Open No. 9-139223).
FIG. 3 is an exploded perspective view showing an embodiment of a fastening structure of a polymer electrolyte fuel cell stack according to the present invention.
FIG. 4 is an assembled perspective view showing an embodiment of a fastening structure of a polymer electrolyte fuel cell stack according to the present invention.
FIG. 5 is a partial side view showing a part of the embodiment of the fastening structure of the polymer electrolyte fuel cell stack according to the present invention.
FIG. 6 is a reference diagram showing a positional relationship between a load point and a through hole in the embodiment of the fastening structure of the polymer electrolyte fuel cell stack according to the present invention.
[Explanation of symbols]
Reference Signs List 20 Stack part 21 Current collector 23 Insulator 24 End plate 25 Tie plate 26 Thread part 27 Tie rod 28 Nut 29 Load point 30 Stack module 70 Guide hole

Claims (5)

A cell stack in which cells are stacked, end plates arranged on both sides of the cell stack in the stacking direction, and arranged on the opposite side of the cell stack with the end plate interposed therebetween, via the end plate A tie plate for applying a compressive load in the stacking direction, wherein the tie plates are provided on one side in the stacking direction of the cell stack, and are symmetrically arranged at positions symmetrical with respect to the cell stack. A fastening structure for a polymer electrolyte fuel cell stack, wherein the fastening structure is provided. 2. The tie plate according to claim 1, wherein a load point is provided on a center line in a longitudinal direction of a cut surface obtained by cutting the cell stack with a plane orthogonal to a stacking direction of the cell stack. 3. Tightening structure for polymer electrolyte fuel cell stack. 3. The polymer electrolyte fuel cell stack according to claim 1, wherein the tie plate is provided with a through-hole for passing a tie rod on a center line in a direction orthogonal to a linear direction connecting the load points. Tightening structure. 4. The fastening structure for a polymer electrolyte fuel cell stack according to claim 1, wherein two load points are provided on the tie plate. 5. The polymer electrolyte fuel cell stack according to claim 1, wherein the number of the tie plates disposed on one side is equal to or less than the total number of load points provided on the tie plate disposed on one side. 6. Tightening structure.

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