JP4773615B2 - Gasket for fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gasket that is a kind of sealing device, and more particularly to a fuel cell gasket that is incorporated into a fuel cell as one of its components.
[0002]
[Prior art]
Generally, a gasket has a cross-sectional shape that concentrates the repulsive force generated when compressing an elastic body in one place or several places, and can obtain the required surface pressure with a relatively small gasket reaction force. Is formed.
[0003]
Further, in the gasket used on the ion exchange membrane side of the fuel cell, when the ion exchange membrane is held by the gasket, it is necessary to generate a gasket reaction force having a size required for the holding.
[0004]
However, the gasket 51 used for this type of application according to the prior art has a cross-sectional shape formed in a mountain shape or a triangular shape as shown in FIG. When the ion exchange membrane 52 is increased to a level that can hold the ion exchange membrane 52, it is difficult to suppress the surface pressure that increases with the ion exchange membrane 52 within the usable range. Therefore, in this prior art, since the surface pressure of the gasket 51 against the ion exchange membrane 52 or the separator 53 becomes excessive, the ion exchange membrane 52 is damaged, or the ion exchange membrane 52 or the carbon separator 53 is damaged. There are things to do.
[0005]
Further, as another gasket shape, there is a flat plate shape as shown in FIG. 6. In this flat plate gasket 51, the reaction force and the surface pressure rapidly increase with respect to the compression amount of the gasket 51. . Therefore, in order to use in an appropriate reaction force and surface pressure range, it is necessary to strictly manage the compression amount of the gasket 51.
[0006]
[Problems to be solved by the invention]
In view of the above points, the present invention has a reaction force that can hold an ion exchange membrane, while suppressing an excessive increase in surface pressure with respect to the ion exchange membrane or separator, and thus the ion exchange membrane or separator is damaged. It is an object of the present invention to provide a fuel cell gasket capable of preventing the above-described problem.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a gasket for a fuel cell according to the present invention is a gasket interposed between a separator and an ion exchange membrane in a fuel cell, the cross-sectional shape of which is larger than the contact width with the separator. in large set shape towards the contact width with, and the contact width of the separator is gradually larger shape with increasing amount of compression during compression, the separator-side contact surface of the gasket and the ion-exchange membrane side contact Each of the surfaces is a convex surface having an arcuate cross section .
[0008]
In the fuel cell gasket of the present invention having the above-described configuration, the contact area between the gasket and the ion exchange membrane is formed to be relatively large, so that the size required to hold the ion exchange membrane is large. Even if this gasket reaction force is generated, it is possible to keep the surface pressure of the gasket against the ion exchange membrane small. Further, since the contact area between the gasket and the separator gradually increases as the compression amount increases, it is possible to keep the gasket reaction force against the compression amount and the rising gradient of the surface pressure low.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 shows a cross section of a fuel cell gasket 1 according to an embodiment of the present invention in a free state. As shown in FIG. 2, a stack 4 is assembled by the gasket 1, a separator 2 and an ion exchange membrane 3. The gasket 1 is compressed by tightening in the vertical direction in the drawing using a through bolt (not shown), and is elastically deformed as indicated by a chain line in FIG. In the stack 4, the ion exchange membrane 3 is arranged between a pair of upper and lower separators 2, and the gaskets 1 are symmetrically arranged between the separators 2 and the ion exchange membrane 3. The separator 2 is usually formed of a carbon fired product, and the ion exchange membrane 3 is formed with a thickness of about 0.05 mm.
[0011]
The gasket 1 includes a planar separator-side contact surface 1a that contacts the separator 2, a planar ion-exchange membrane-side contact surface 1b that contacts the ion-exchange membrane 3, and ions from the separator-side contact surface 1a. The inner and outer side surfaces 1c are inclined so that the interval gradually increases toward the exchange membrane side contact surface 1b, and is formed in a substantially trapezoidal cross section. It is formed in a trapezoidal shape with the short side and the ion exchange membrane side contact surface 1b as the long side. Each of the four corners of the trapezoid is rounded in a circular arc shape.
[0012]
The gasket 1 is formed by using a rubber-like elastic material such as silicone rubber, EPDM, or fluoro rubber as a molding material.
[0013]
The gasket 1 is formed in a shape in which the cross-sectional shape of the gasket 1 is set such that the contact width B with the ion exchange membrane 3 is larger than the contact width A with the separator 2, and the separator 1 is compressed when compressed. 2 is formed in a shape that gradually increases from A to A ′ (= 1.2 to 2 × A) as the amount of compression increases. The contact width A with the separator 2 is usually set to about 1 to 5 mm, preferably about 1.5 to 3 mm.
[0014]
By using the gasket 1 to assemble the stack 4 as shown in FIG. 2 and tighten the through bolts, the gasket 1 is compressed and elastically deformed as shown by the chain line in FIG. At this time, the reaction force of the gasket 1 is generated at 0.5 to 5 N / mm. However, since the contact width with the separator 2 increases from A to A ′, the generated surface pressure is set to 0. It can be suppressed to about 25 to 2.5 MPa.
[0015]
Therefore, according to the gasket 1 having the above-described configuration, even if a gasket reaction force having a magnitude required for holding the ion exchange membrane 3 is generated, the magnitude of the surface pressure of the gasket 1 against the ion exchange membrane 3 is large. In addition, since the contact area between the gasket 1 and the separator 2 gradually increases as the amount of compression increases, it is possible to keep the gasket reaction force against the amount of compression and the rising gradient of the surface pressure low. Can do. Therefore, it is possible to prevent the separator 2 or the ion exchange membrane 3 from being damaged due to excessive increase in the surface pressure.
[0016]
In addition, regarding the cross-sectional shape of the gasket 1, in the above-described embodiment, the separator-side contact surface 1a and the ion-exchange membrane-side contact surface 1b are both flat (straight), but as shown in FIG. Reference numerals 1a and 1b are convex surfaces having an arcuate cross section , and can provide the same operational effects.
[0017]
Moreover, in the said Example, as shown in FIG. 2, although the upper and lower paired gasket 1 made all the shape of an Example, as shown in FIG. 4, the gasket 1 of one Example shape was made into another shape. It may be used in combination with the gasket 5.
[0018]
【The invention's effect】
The present invention has the following effects.
[0019]
That is, in the fuel cell gasket of the present invention having the above-described configuration, the contact area between the gasket and the ion exchange membrane is formed to be relatively large, so that it is required to hold the ion exchange membrane. Even if a large gasket reaction force is generated, the surface pressure of the gasket against the ion exchange membrane can be kept small, and the contact area between the gasket and the separator gradually increases as the amount of compression increases. Therefore, the gasket reaction force against the compression amount and the rising gradient of the surface pressure can be kept low. Therefore, it is possible to prevent the separator or the ion exchange membrane from being damaged due to excessive increase in the surface pressure. Moreover, since the variation of the gasket compression amount by a separator can be absorbed, the assembly | attachment precision of a stack can be eased.
[0020]
Further, since the ion exchange membrane can be held by the fuel cell gasket of the present invention, a member for fixing the ion exchange membrane can be omitted and the area of the expensive ion exchange membrane can be reduced. Material costs can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a fuel cell gasket according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an assembled state (before tightening) of the fuel cell gasket. FIG. 4 is a cross-sectional view showing another example of the shape. FIG. 4 is a cross-sectional view showing another example of the assembled state of the fuel cell gasket (before tightening). FIG. 5 is an assembled state of the fuel cell gasket according to the conventional example. Sectional view showing (after tightening) [FIG. 6] Cross-sectional view showing the assembled state (after tightening) of a fuel cell gasket according to another conventional example [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel cell gasket 1a Separator side contact surface 1b Ion exchange membrane side contact surface 1c Side surface 2 Separator 3 Ion exchange membrane 4 Stack 5 Gasket

Claims (1)

In the gasket (1) interposed between the separator (2) and the ion exchange membrane (3) in the fuel cell,
The cross-sectional shape is a shape in which the contact width (B) with the ion exchange membrane (3) is set larger than the contact width (A) with the separator (2), and with the separator (2) during compression The contact width (A) is gradually increased as the amount of compression increases ,
A separator for a fuel cell, wherein the separator-side contact surface (1a) and the ion-exchange membrane-side contact surface (1b) of the gasket (1) are both convex surfaces having an arcuate cross section .

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