JPS61143946A - Manifold mounting and sealing of fuel cell - Google Patents

Abstract

PURPOSE:To increase adhering ability of a sealing material by setting a pair of auxiliary sealing members in sealing part, arranging raw fluorine rubber containing foaming agent and curing agent in a space formed by sealing members, tightening the auxiliary sealing members, then flaming and curing the raw rubber. CONSTITUTION:A pair of frame-shaped fitted grooves 5, 5 and a frame-shaped concavity 6 are formed on each sealing surface of a cell frame 3, and a pair of auxiliary sealing members 7, 7 made of cured fluorine resin rubber are fixed by fitting their projections to the grooves 5, 5. A string-shaped raw fluorine rubber containing foaming agent and curing agent, which serves as a main sealing member 8, is filled to the concavity 6 after being coated with fluorine resin grease. Since the raw rubber is expanded, its cross section area is made smaller than the space formed by the concavity. After the auxiliary sealing member are tightened, the raw fluorine rubber is heated to foam and cure. The foamed rubber is pressed against the sealing surface to form the main sealing member. Thereby, sealing ability is increased and gas leak from each sealing part is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a method for attaching and sealing a fuel cell manifold, particularly when attaching an IL contact manifold to a battery stack or attaching a manifold to a battery frame that tightens the battery stack from the outer periphery. The present invention relates to a method of sealing each seal portion.

(b) Conventional techniques As for the attachment of the manifold to the battery stack, there is a well-known method of attaching the manifold (2) directly to the battery stack (1) (see FIG.
As already proposed in No. 97679, the battery stack (1
) is used to indirectly attach the manifold (2) using a battery frame (3) that is tightened from the outer periphery (see Fig. 2).

In either case, the seal part (4) between the battery stack and the seven-fold mounting surface, or each seal part between the battery stack (1) and the battery frame (3), and between this battery frame and the manifold mounting surface. (41) and (42) are tightened and fixed with a heat-resistant and acid-resistant sealing material interposed therebetween.

Vulcanized fluororubber (trade name: Paiton Rubber), which has been widely used as a sealing material, has the strength and elasticity required for a backing, but it has poor flexibility and is difficult to handle due to unevenness or distortion. Since it lacks adhesion to certain sealing surfaces, such as battery stack stacking surfaces and manifold mounting surfaces, it can be used as a double layer with highly flexible unvulcanized fluorine rubber.

However, unvulcanized fluororubber hardens due to the heat generated during battery operation, and the seal portion gradually loosens, reducing sealing performance and causing gas leakage. Therefore, it is necessary to retighten the seal portion after the battery is activated, but as the scale of the battery increases, retightening becomes time consuming and difficult, which poses practical problems.

(c) Problems to be solved by the invention This invention improves the adhesion of the sealing material to effectively prevent gas leakage, eliminates the need to retighten the sealing material, and improves safety and workability. .

(d) Means for Solving the Problems This invention provides a method in which when a manifold is attached to a battery stack directly or indirectly through a battery frame, a pair of auxiliary sealing materials are interposed in each necessary sealing portion, and the sealing material is After arranging the fluorine-based raw rubber containing a foaming agent and a hardening agent in the partitioned space and tightening the auxiliary sealing material, the fluorine-based raw rubber is simultaneously foamed and cured, thereby expanding and foaming in the space. The body constitutes the main sealing material.

(E) Function According to the present invention, the main sealing material is cured by heat and simultaneously foams and expands into an elastic body having closed cells between a pair of auxiliary sealing materials tightened in advance. Even if there are irregularities, it is tightly bonded to the irregularities, resulting in extremely good sealing performance, and the sealing part does not loosen as in the past, eliminating the need for troublesome and difficult retightening work.

(F) Embodiment An embodiment of the present invention will be described with reference to the sealing method in the case of the method shown in FIG.

The battery frame (3) is brought into contact with each circumferential surface of the battery stack (1) via the seal portion (41), and these adjacent frames are elastically connected to each other and the battery stack (1) is tightened from the outer circumference. An example of this elastic connection means is disclosed in the above-mentioned Japanese Patent Application Laid-open No. 58-1.
Since it is disclosed in Japanese Patent No. 97679, its details will be omitted.

Each sealing surface of the battery frame (3) has a pair of frame-shaped engagement grooves (5) (5) and a frame-shaped recess (6) between these grooves, as shown in FIGS. 3 to 5. and a pair of auxiliary sealing materials (7) (7) made of vulcanized fluororubber (Piton rubber).
) is fixed with its protrusion extending into each of the engagement grooves (5) (5).

The fluorine-based raw rubber containing a foaming agent (e.g. ammonium hydrogen carbonate) and a hardening agent (e.g. amine-based material), which becomes the main sealing material (8), is string-shaped as shown in Figure 3, and is attached to the battery frame (3).
(After applying fluororesin grease in advance to the depression (6),
Can be fitted. Since this string-like material expands as will be described later, its cross-sectional area is made smaller than the space formed by the pair of engagement grooves and the recess.

31iA shows the stack side of the battery frame (3), and FIG. 4 also shows a partially enlarged view of the manifold side, but the structure of the seal part is the same.

Seal part (41) between battery stack (1) and battery frame (3)
), due to the elastic connection between adjacent frames as described above,
Also, the seal part (42) between the battery frame (3) and the manifold (2)
), by tightening the bolts (9), a pair of auxiliary sealing materials (7) and (7) are fixed to both sealing surfaces of the frame (3).
7) (7) are pressed against the battery stack surface and the manifold mounting surface, respectively. This state is clearly shown in FIG. 5(a).

Then, as the temperature of the battery stack (1) increases (approximately 130°C), the main sealing material (8), which was initially string-like, simultaneously foams and hardens, as shown exaggeratedly in Figure 5 (b). The foam expands into a foam with closed cells. This foam fills the space formed by the pair of auxiliary sealing materials (7) (7) and the depression (6), and its strong expansion force creates a small gap between the auxiliary sealing material (7), the battery stack surface, and the manifold mounting surface. The main sealing material (8) absorbs the unevenness of each sealing surface and has high airtightness. The pair of auxiliary sealing materials <7) (7) doubles as a temporary seal and a member for suppressing lateral expansion of the main sealing material (8).

Figure 6 is a sectional view of both seal parts (41) and (42).
The figure is a sectional view taken along the line xx in FIG. 6. In these figures, (8') shows the skin layer of the main sealing material (8) after foaming.

The above embodiment has been described for the case of the method shown in FIG. 2, but the sealing method in the case of the method shown in FIG. 1 is also substantially the same as that of the previous embodiment, as shown in FIG. However, only the upper and lower mounting surfaces of this manifold (2) can be fixed with bolts (not shown) that are tightened to the upper and lower end plates (not shown) of the battery stack (1).

(G) Effects of the Invention According to the present invention, when a manifold is attached to a battery stack directly or through a battery frame, each seal part includes a pair of auxiliary sealing materials, a foaming agent inserted between the sealing materials, and a curing agent. The auxiliary sealing material is tightened, and the fluorine-based raw rubber is foamed and cured by heating afterward, and the foamed elastic body with a large expansion force strongly presses against the sealing surface to form the main seal. Since it is made of a material, the sealing properties are significantly improved and gas leakage from each sealing part can be prevented, and the conventional troublesome and difficult retightening after curing is no longer necessary. Further, since the heating is performed during the battery start-up preparation period, that is, when the temperature of the battery stack is increased by circulating heated air, no special heat treatment is required.

[Brief explanation of drawings]

1 and 2 show partial plan views of the battery stack,
Figure 1 shows the case where the manifold is directly attached, and Figure 2 shows the case where it is attached via the battery frame. 3 to 7 show an embodiment of the method of the present invention, and FIG. 3 is a perspective view of the battery frame;
Figure 4 is a cross-sectional view of the main part of the same as above, and Figure 5 (A) (
B) is a schematic diagram showing the state before foaming and after foaming, respectively.
The figure is a cross-sectional view of the seal portion, and FIG. 7 is a cross-sectional view taken along the line XX in FIG. 6. Further, FIG. 8 is a sectional view of a seal portion showing another embodiment of the method of the present invention. 1: Battery stack, 2: Manifold, 3: Battery frame, 4.
4x, 42: Each seal part, 5: Engagement groove, 6: Recess, 7
．． 7: Two pairs of auxiliary sealing materials, 8: Main sealing material.

Claims (1)

[Claims] (1) A pair of auxiliary sealing materials are interposed in the sealing portion between the battery stack and the manifold, or in each sealing portion between the battery stack and the battery frame and between the battery frame and the manifold, and the sealing material is used to partition the sealing portion between the battery stack and the manifold. After placing a fluorine-based raw rubber containing a foaming agent and a hardening agent in the space, and tightening the auxiliary sealing material, the fluorine-based raw rubber is foamed and cured, so that the elastic foam expanded in the space is A method for attaching and sealing a fuel cell manifold, characterized in that it constitutes a main sealing material.