JP2002063929A - Stack structure of fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stack structure of a fuel cell wherein a superior adhesion between cells by effecting a uniform pressure against the whole laminated surface of the cell is possible to be provided without increasing the outer dimension of the stack structure and without reduction of generation ability of respective cells. SOLUTION: A pair of end plates 4 and a cell laminated body 3 mutually laminated and pinched between the end plates 4 are arranged in the space formed by an endless belt body 26. Plural threads 8 are made on an erected part 26B of the belt body, and the inner end of the threads abut on the end plate 4. The outer end of the thread 8 protrudes outward the erected part 26B, and a nut 8 is threaded. When the nut is rotated, the screw 8 is threaded back and forth, and the pressure for the cell laminated body 3 changes. More detailed pressure adjustment can be made by selecting either one of the nuts and it rotating it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell stack structure, and more particularly, to a fuel cell in which a plurality of power generating elements (cells) are stacked and end plates are arranged at the beginning and end of the stack to apply pressure in the stacking direction. The present invention relates to a battery stack structure.

[0002]

2. Description of the Related Art A fuel cell is generally used by arranging a plurality of power generating elements called cells and connecting them to form a fuel cell stack. Here, the cell has a structure in which a polymer conductive film through which hydrogen ions pass is sandwiched between two electrodes including a hydrogen electrode and an oxygen electrode, and both sides are further surrounded by separators. When oxygen and hydrogen are supplied independently of each other to the passage provided in the separator, the hydrogen gas is converted into hydrogen ions by the hydrogen electrode and moves to the oxygen electrode side through the conductor film.
At this time, hydrogen emits electrons, which generate a potential difference. Although the potential difference is less than 1 volt per cell, a high voltage can be obtained by stacking many cells and connecting them in series.

In order to improve the output of one cell,
Adhesion between the conductor film and the electrode is required. Further, in order to improve the output of the entire fuel cell stack, it is necessary to improve the degree of adhesion between the cells to prevent power transmission loss at the connection portion, and to provide a desired compressive force to the cell stack. Need to work. For this reason, in the conventional fuel cell stack structure 51 shown in FIG. 4, the front of the top cell 2 of the cell stack 3 is sandwiched by the cell stack 3 in which a plurality of cells 2 stacked on each other are assembled. The end plates 54, 54 are arranged behind the last cell 2 and the last cell 2, respectively, and pressurizing means 55 for pressing the end plates 54, 54 in a direction approaching each other is provided to press the cells in the stacking direction. Here, the outer dimensions of the end plate 54 are formed larger than the outer dimensions of each cell 2, and four holes are formed at positions outside the projection surface of each cell 2 of the end plate 54. Are arranged coaxially with the holes of the end plates facing each other. The pressing means 55 includes a pressing bolt 58 and a nut 59, and the pressing bolt 58
Of the cell stack 3 between the end plates 54, 54 by screwing and fastening a nut 59 to a pressure bolt 58 protruding outside the end plate 54. I'm pressing.

In another conventional fuel cell stack structure 61 shown in FIG. 5, the arrangement of the end plates 64 so as to sandwich the cell stack 3 is the same as that of FIG. 2, a through hole is formed coaxially, a pressure bolt 68 is inserted through the through hole, and a nut 69 is screwed and fastened to the pressure bolt 68 protruding outside the end plate 64, thereby forming an end plate. The cell stack 3 is pressurized between 64 and 64. The configuration in FIG. 5 schematically shows a stack structure described in US Pat. No. 5,484,666.

[0005]

However, in the conventional structure shown in FIG. 4, since four pressure bolts 54 are located outside the outer contour of the cell 2, the entire fuel cell stack structure 51 is formed. In view of the above, the size of the cell 2 in the stacking surface direction increases, and the configuration becomes bulky as a whole. Further, since the pressure bolts 58 are arranged at positions that do not interfere with the cell 2, that is, at the four corners of the end plate 54, the four corners of the end plate 54 are loaded by fastening the nut 59. Therefore, if the rigidity of the end plate 54 is not made sufficiently large, the adhesion at the center of the cell stacking surface 3 becomes low, so that good adhesion between the cells 2 cannot be obtained. In order to increase the rigidity of the end plate 54, it is necessary to increase the thickness of the end plate or to use a material having little elastic deformation. Then, the size or weight of the entire stack structure also increases in the stacking direction.

In the conventional structure shown in FIG. 5, since the area of the stacking surface of the cells 2 is reduced by the through holes, the power generation capacity of each cell 2 is reduced by that amount.

Therefore, the present invention provides a method for forming a uniform structure on the entire stacking surface of a cell without increasing the external dimensions of the entire stack structure in the direction of the stacking surface of the cell and without reducing the power generation capacity of the cell. An object of the present invention is to provide a fuel cell stack structure capable of providing good adhesion between cells by applying a pressing force.

[0008]

In order to achieve the above object, the present invention provides a cell stack in which a plurality of cells stacked on each other are assembled, and a top of the cell stack so as to sandwich the cell stack. Comprising a pair of end plates disposed in front of the last cell and behind the last cell, and pressurizing means for pressing the end plates in a direction approaching each other in order to press the cells in the stacking direction. In the battery stack structure, the pressurizing means includes an external structure and a pressing mechanism, and the external structure includes:
A base extending in the stacking direction along the cell stack, and a pair of upright portions integral with the base and located outside the pair of end plates in the stacking direction and facing the end plates; The pressing mechanism is arranged so as to be able to abut on one end plate facing the at least one standing portion while being supported by at least one of the standing portions, and to connect the one end plate to the other end plate. The present invention provides a fuel cell stack structure that is pressed in a direction.

Here, in the external structure, a connecting portion for integrally connecting the standing portions is provided on a side opposite to the base with respect to the cell laminate, and a plate-like member having an endless cross section as a whole is provided. It is preferable that the width of the plate member is equal to or smaller than the cell width.

It is preferable that the plate-like member surrounds and protects the cell laminate, the end plate and the pressing member in the laminating direction.

Further, it is preferable that the pressing mechanism is provided with a displacement adjusting / fixing means capable of moving in the stacking direction and fixing the position after the movement.

Further, the pressing mechanism preferably includes a pressing force adjusting means capable of adjusting a pressing force for pressing the one end plate toward the other end plate.

[0013] In addition, it is preferable that a plurality of the pressing mechanisms are provided on the at least one end plate, and the plurality of pressing mechanisms are selectively operated.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel cell stack structure according to a first embodiment of the present invention will be described with reference to FIG. The first embodiment shows a basic structure of the present invention. As shown in FIG. 1, the fuel cell stack structure 1 includes a cell stack 3 in which a plurality of cells 2 stacked together are assembled, and a pair of end plates 4 arranged so as to sandwich the cell stack 3. 4 and pressurizing means 5 for pressing the end plates 4 in directions approaching each other in order to press the cells 2 in the stacking direction.

The structure of each cell 2 is the same as that of the conventional cell, and includes a hydrogen electrode, a conductor film disposed between the oxygen electrode and the two electrodes, a hydrogen electrode of one cell and an oxygen electrode of the other cell. It is provided with a separator for partitioning the electrode. As described above, when oxygen and hydrogen are supplied independently of each other to the passage provided in the separator, the hydrogen gas is converted into hydrogen ions by the hydrogen electrode, and moves to the oxygen electrode side through the conductor film. At this time, hydrogen emits electrons to generate a potential difference. The cell stack 3 is formed by stacking adjacent cells 2 and electrically connecting them, and a desired high voltage can be obtained by stacking a large number of cells 2 and connecting them in series.

Each end plate 4 is a plate-like body having a uniform thickness, and has substantially the same outer shape as the outer shape of the cell 2 in the direction of the lamination surface.

The pressing means 5 comprises an external structure 6 and a pressing mechanism 7
The external structure 6 is a bracket having a U-shaped cross section. The base 6A extends in the stacking direction along the cell stack 3 and a pair of end plates 4 integral with the end of the base 6A. 4, a pair of standing portions 6B which are located outside in the stacking direction and face the end plate. Here, the width (width in the direction perpendicular to the paper) of the base 6A and the standing portion 6B is smaller than the width of the cell stacking surface (width in the direction perpendicular to the paper) or is at most the same. In addition, a penetrating female screw for screwing with a bolt 7, 7 described later is formed in the standing portion 6B.

The pressing mechanism 7 is composed of bolts 8, 8 and nuts 9, 9. The bolt 8 is screwed and supported by the female screw of each of the erected portions 6B, 6B. , Projecting from the standing portions 6B, 6B, and screwed with the nut 9. The bolts 8, 8 have a sufficient axial length, and can cope with a case where cells having different thicknesses are arranged in a stack structure or a case where the number of cells changes.

In the above configuration, when the cell laminate 3 is sandwiched between the end plates 4 and 4, the cell laminate 3 is disposed between the upright portions 6 B and 6 B, and the nut 9 is rotated using a wrench or the like (not shown). The inner end of the bolt 8 comes into contact with the central portion of the end plate 4 by the screw advance of the bolt 8, and the end plate 4 is pressed in the direction of the other end plate 4. By adjusting the screw retreat amount of the bolt 8, an optimum pressing force can be applied to the cells even when cells having different thicknesses are arranged in a stack structure or when the number of cells changes. In other words, the combination of the bolt 8 and the nut 9 is capable of moving in the cell stacking direction and functioning as a displacement adjustment fixing means capable of fixing the position after the movement, and one end plate is moved in the other end plate direction. It exerts a function as a pressing force adjusting means capable of adjusting the pressing force applied to the device.

A fuel cell stack structure according to a second embodiment of the present invention will be described with reference to FIG. The fuel cell stack structure 11 according to the second embodiment uses an endless band plate 16 as an external structure. The endless strip 16 surrounds the end plate 4 and the cell stack 3 in the cell stacking direction on the inner peripheral surface. And the width W of the strip 16
Are formed smaller than the width of the cell. Further, the material of the endless band plate body 16 is metal or plastic, and an elastic body such as rubber may be partially used.

The endless strip 16 has a bottom portion 16A corresponding to the base portion 6A and the upright portion 6B of the first embodiment, and an end wall portion 1A.
6B. Further, with respect to the cell stack 3, the bottom 16A
And a connecting portion 16C provided on the opposite side to connect the end wall portions 16B integrally, and has an endless shape by the bottom portion 16A, the end wall portion 16B, and the connecting portion 16C. Here, the end wall portion 16B
The length H of the vertical side is shorter than the vertical side of the end plate 4, and the inclined portion 1 in which both ends of the bottom 16A and the connecting portion 16C are inclined by that length
6D, and is integrally connected to the end wall 16B.
Further, the bolt 8 and the nut 9 constituting the pressing mechanism 7 are provided only on one end wall 16B.

In the above configuration, the cell stack 3 is sandwiched between the end plates 4, 4, and one end plate 4 is in endless contact with the inclined portion 16 D on the end wall side where no pressing mechanism is provided. It is arranged in the space inside the band plate body 16. When the nut 9 is rotated using a wrench or the like (not shown), the inner end of the bolt 8 abuts on the center of the other end plate 4 by screwing the bolt 8 so that the end plate 4 is connected to the one end described above. Pressure is applied in the direction of the plate 4. By adjusting the amount of screw advance / retreat, an optimum pressing force can be applied to the cells even when cells having different thicknesses are arranged in a stack structure or when the number of cells changes.

In the second embodiment, the end plate 4 and the cell stack 3 are formed in an endless shape and are surrounded in the cell stacking direction. The protection effect of the plate 4 is high. In addition, since the external structure is formed of the thin band plate body 16 and the width W of the band plate body 16 is formed smaller than the width of the cell, the entire apparatus becomes compact and lightweight. Because this was an endless shape,
This is because a certain strength can be obtained as compared with the first embodiment.

Next, a fuel cell stack structure according to a third embodiment of the present invention will be described with reference to FIG.
Stack structure 21 of fuel cell according to third embodiment
As in the second embodiment, an endless band plate 26 is used as an external structure, but its cross-sectional shape is rectangular, and its width W is formed slightly larger than the width of the cell. ing. Further, a plurality of (four in the illustrated example) pressing mechanisms 7 are provided on one standing portion 26B. Further, a lid 27 having a rectangular opening end of the endless band plate body 26 and an opening 27a formed in the center is detachably provided. Therefore, the cell stack 3 and the end plate 4 are protected in the endless band plate 26 and the cover 27.

In the above configuration, the cell stack 3 is sandwiched between the end plates 4 and 4 and arranged in the space within the endless band plate 26.
When any or all of the nuts 9 are rotated using a wrench or the like (not shown), the inner ends of the bolts 8 contact the one end plate 4 by screwing of the bolts 8 and the end plate 4 is connected to the other end plate. Press in four directions. By adjusting the screw retreat amount of the bolt 8, an optimum pressing force can be applied to the cells even when cells having different thicknesses are arranged in a stack structure or when the number of cells changes.

In the third embodiment, as compared with the above-described embodiment, not only the protection effect of the cell 2 and the end plate 4 can be further enhanced, but also any one of the plurality of pressing mechanisms 7 or the two. By selectively operating more than one cell, an optimum pressure and pressure distribution can be given to the cell stack 3.

The stack structure of the fuel cell according to the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims.

For example, in the above-mentioned pressurizing mechanism, bolts and nuts are used, but instead of these, a compression spring, a compression rubber, a telescopic hydraulic cylinder can be provided between the standing portion and the end plate. May be arranged.

Further, in the first embodiment, the pressurizing mechanism is provided on both the upright portions 6B, 6B. However, one end plate is brought into direct contact with the upright portion, and the other upright portion is brought into contact with the upright portion. A pressurization mechanism may be provided only to pressurize the cell stack.

Further, in the second embodiment, one pressing mechanism is provided, and in the third embodiment, four pressing mechanisms are provided. However, in order to obtain a desired pressure, Is not limited to these numbers. Further, in the second and third embodiments, the pressurizing mechanism is provided only on one of the upright portions, but the pressurizing mechanism is provided on the other upright portion as necessary. You may.

[0031]

According to the fuel cell stack structure of the first aspect, the pressurizing means is constituted by the external structure and the pressing mechanism, and the external structure extends in the stacking direction along the cell stack. A base, and a pair of uprights, which are integral with the base and are located outside the pair of end plates in the stacking direction and face the end plates, are provided, and the pressing mechanism is supported by at least one of the uprights. In this state, it is arranged so as to be able to abut one end plate facing at least one of the standing portions, and the one end plate is pressed in the direction of the other end plate. Since the pressure means is not located, the stack structure as a whole has a compact shape without greatly exceeding the outer contour of the cell, and since the pressure means does not penetrate the inside of the cell, the power generation capacity of the cell is reduced. It does not lower.

According to the fuel cell stack structure of the second aspect, the outer structure is constituted by a plate-like member having an endless cross section as a whole, and the width of the plate-like member is the same as the cell width or the cell width. Since it is formed smaller than the width, the volume of the entire stack structure can be reduced.

According to the fuel cell stack structure of the third aspect, the plate-like member surrounds the cell stack, the end plate, and the pressing member in the stacking direction. Can be physically protected.

According to the fuel cell stack structure of the fourth aspect, by providing the displacement adjusting and fixing means,
Even if the number of stacks changes, good adhesion can be provided to each cell.

According to the fuel cell stack structure of the fifth aspect, since the pressing force adjusting means is provided, the pressing force can be adjusted arbitrarily, and even if cells having different thicknesses are applied, each cell has a different thickness. Good adhesive strength can be provided.

According to the fuel cell stack structure of the present invention, the number of pressing means and the distribution of the pressing force can be arbitrarily adjusted by selectively operating the plurality of pressing mechanisms. A more uniform pressing force can be applied.

[Brief description of the drawings]

FIG. 1 is a side view showing a fuel cell stack structure according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a fuel cell stack structure according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing a fuel cell stack structure according to a third embodiment of the present invention.

FIG. 4 is a perspective view showing a stack structure of a conventional fuel cell.

FIG. 5 is a perspective view showing another conventional fuel cell stack structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11, 21 Stack structure of fuel cell 2 Cell 3 Cell laminated body 4 End plate 6 Bracket as external structure 16, 26 Endless band plate as external structure 7 Pressing mechanism 8 Bolt of pressing mechanism 9 Pressing mechanism Nuts

Claims (6)

[Claims] 1. A cell stack in which a plurality of cells stacked together are assembled, and a pair of cells arranged in front of a first cell and behind a last cell of the cell stack so as to sandwich the cell stack. In a fuel cell stack structure comprising: an end plate; and pressurizing means for pressing the end plates in a direction to approach each other in order to press the cells in the stacking direction, wherein the pressurizing means comprises an external structure and A press mechanism, wherein the external structure has a base extending along the cell stack in the stacking direction, and the end plate being integral with the base and positioned outside the pair of end plates in the stacking direction. And a pair of upright portions facing the at least one of the upright portions while the pressing mechanism is supported by at least one of the upright portions. Wherein the one end plate is pressed in the direction of the other end plate. Stack structure of the battery. 2. The external structure comprises a plate-like member having an endless cross section as a whole, provided with a connecting portion for integrally connecting the standing portions on a side opposite to the base portion with respect to the cell laminate. 2. The fuel cell stack structure according to claim 1, wherein the width of the plate member is equal to or smaller than the cell width. 3. The fuel cell stack structure according to claim 2, wherein the plate-like member surrounds and protects the cell stack, the end plate, and the pressing member in the stacking direction. 4. The fuel cell stack structure according to claim 1, wherein the pressing mechanism includes a displacement amount adjusting and fixing means which can move in the stacking direction and fix a position after the movement. . 5. The fuel cell according to claim 1, wherein the pressing mechanism includes a pressing force adjusting means capable of adjusting a pressing force for pressing the one end plate toward the other end plate. Stack structure. 6. The fuel cell stack structure according to claim 1, wherein a plurality of said pressing mechanisms are provided on said at least one end plate, and said plurality of pressing mechanisms are selectively operated.