JPH0334840Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention is a fuel cell in which unit cells are stacked in a columnar manner, in particular, a fuel cell in which a reactive gas consisting of a fuel gas and an oxidizing gas is supplied and exhausted from the side of the cell stack. The present invention relates to a gas seal structure between an opening flange surface of a manifold lid and a seal layer provided on a side surface of the battery stack.

[Prior art and its problems]

In a fuel cell, fuel gas and oxidizing gas are supplied to the sides of the cell stack in directions orthogonal to each other.
Manifolds are attached to all sides of the side for exhaust. Leakage from between the seal layer on the side of the battery stack and the opening flange surface of the manifold lid reduces fuel cell efficiency and induces an explosive reaction between hydrogen in the fuel gas and oxygen in the oxidizing gas. Therefore, a sealing structure is required to prevent leakage between the sealing layer of the battery stack and the opening flange surface of the manifold lid, and for this purpose, a sealing structure with a packing interposed has conventionally been used. The prior art will be explained below with reference to the drawings. FIG. 1 is an exploded perspective view of a fuel cell, FIG. 2 is a plan view, and FIG. 3 is a partially enlarged view of a seal structure according to the prior art.

In FIG. 1, an oxidizing gas supply manifold 2 and an exhaust manifold 3 are arranged on opposite sides of the fuel cell stack 1 in which unit cells are stacked in a columnar manner. A fuel gas supply manifold 4 and an exhaust manifold 5 are arranged on the side surfaces in the right angle direction. The battery stack 1 has multiple rows of grooves provided in the directions of arrows A and B, and multiple rows of grooves provided in the directions of arrows C and D perpendicular to these, and oxidation flowing in the directions of arrows A and B. The gas and fuel gas flowing in the directions of arrows C and D undergo an electrochemical reaction within the unit cell to generate electricity.

As shown in FIG. 2, the manifolds 2, 3, 4, and 5 are provided with an oxidizing gas inlet pipe 2a, an outlet pipe 3a, a fuel gas inlet pipe 4a, and an outlet pipe 5, respectively.
a is installed. In FIG. 2, the opening flange surfaces of the manifold lids of the oxidizing gas supply, exhaust manifolds 2 and 3, the fuel gas supply and exhaust manifolds 4 and 5, and the sealing layers of the battery stack 1 are shown. A gasket is interposed between the peripheral edge and the side surface, and the manifold lid and the battery stack 1 are tightened by a tightening member (not shown). FIG. 3 is a partially enlarged view of the packing part, and shows that the packing 7 inserted into the groove of the opening flange surface of the manifold lid of the manifold 3 is between the sealing layer 6 of the battery stack 1 and the opening flange surface. is interposed in. Here, the side surfaces of the battery stack 1 are not smooth because they are made up of a stack of unit cells. Therefore, the sealing layer 6 applied to this side surface
The thickness of each layer of the unit cell will be different.

During operation of the fuel cell, oxidizing gas enters through the inlet pipe 2a and is discharged via the manifold 2, the cell stack 1, the manifold 3, and the outlet pipe 3a. On the other hand, fuel gas enters through the inlet pipe 4a and is discharged via the manifold 4, the battery stack 1, the manifold 5, and the outlet pipe 5a. Therefore, it is necessary to prevent these reactive gases from leaking from the joint between the opening flange surface of the manifold lid and the sealing layer applied to the side surface of the battery stack. For this reason, the sealing layer 6 on the side surface of the battery stack 1 is smoothly surfaced, and close contact with the interposed packing 7 is achieved. Note that the exposed parts of the battery stack 1 that are not covered by the manifolds, for example, the corners of the battery stack 1 that are not covered by the manifolds 3 and 4, are protected by a sealing layer applied to the peripheral edge of the side surface of the battery stack 1. Battery laminate 1
Gas leakage from inside is prevented.

Now, a fuel cell is generally operated at a temperature higher than room temperature, for example, a phosphoric acid fuel cell is operated at a temperature of about 200°C. 4,5
A dimensional change occurs due to the difference in thermal expansion between the opening flange surface of the manifold lid and the opening flange surface of the manifold lid. Therefore, it is necessary to absorb the change due to this difference in thermal expansion by some means, but in the conventional manifold mounting structure, the packing 7 sticks to the sealing layer 6, and when a difference in thermal expansion occurs, the sealing layer 6 Excessive stress and strain occur, and as mentioned above, the thickness of the sealing layer varies from unit cell layer to unit cell layer, resulting in locally excessive stress and strain, and when the heat cycle associated with operation and stop is repeated. Cracks and cracks occur in the sealing layer 6 due to fatigue, resulting in a reduction in airtightness. This was particularly noticeable when the gasket 7 was in the shape of a flat plate frame.

[Purpose of invention]

In view of the above points, this design is able to ensure sufficient airtightness between the battery stack and the manifold lid even when subjected to repeated heat cycles due to the temperature difference between room temperature and operating temperature. The purpose is to provide fuel cells.

[Summary of the idea]

In order to achieve the above object, this invention includes a fuel cell stack in which unit cells are stacked in a columnar manner, a reactant gas supply/discharge manifold having an opening flange, and an opening in the peripheral edge of the side surface of the fuel cell stack. In the fuel cell equipped with a sealing layer provided opposite to the flange, a frame-shaped seat made of a material having substantially the same coefficient of thermal expansion as the fuel cell stack is interposed between the opening flange and the sealing layer. shall be equipped.

[Example of idea]

Embodiments of the present invention will be described below based on the drawings. In addition, the same reference numerals are attached to the same parts in the drawings as in FIGS. 1 to 3. In FIG. 4, the sealing layer applied to the peripheral edge of the side surface of the battery stack 1, the supply of oxidizing gas, and the exhaust manifolds 2 and 3 are shown.
and fuel gas supply and exhaust manifold 4,
A frame-shaped seat 8 made of a material having approximately the same coefficient of thermal expansion as the battery stack 1, such as amber or carbon, is interposed between the opening flange surface of each manifold and the opening flange surface of each manifold. The ring packing 9 is inserted. In this embodiment, which has the structure in which the seat 8 is interposed as described above, the operation of the fuel cell using the reaction gas and the electrochemical reaction are the same as in the prior art.

FIG. 5 shows the battery stack 1 and the manifold 3 separated from each other.
A frame-shaped seat 8 is interposed between the seal layer applied to the peripheral edge of the side surface of the manifold 3 and the opening flange surface 3b of the manifold 3. A ring patch 9 is shown. FIG. 6 is an enlarged perspective view of the circle p in FIG. 4, showing how the frame-shaped seat 8 and O-ring packing 9 are attached.

Now, the sealing between the sealing layer 6 on the side surface of the battery stack 1 and the opening flange surface of each manifold is performed by interposing the frame-shaped seat 8 as explained in the above embodiment. Sealing is therefore performed between the sealing layer 6 and the frame-shaped seat 8 and between the frame-shaped seat 8 and the opening flange surface. Between the former seal layer 6 and the frame-shaped seat 8, airtightness can be maintained by flattening the seal layer 6 and bringing it into close contact with the seat 8. Note that since the seat 8 is made of a material with a coefficient of thermal expansion that is almost the same as that of the battery stack 1, even if the temperature rises due to the operation of the fuel cell, there will be no difference in thermal expansion between the battery stack 1 and the seat 8 due to the temperature difference. Noticeably small. Therefore, no excessive stress or distortion occurs in the seal layer 6.

On the other hand, between the seat 8 and the opening flange surface of each manifold, an O-ring packing 9 inserted into a packing groove provided in the opening flange surface of each manifold is inserted between the seat 8 and the opening flange surface of each manifold. The O-ring packing 9 and the opening flange surface are brought into close contact with the seat 8 to maintain airtightness.
Even if the operating temperature rises due to the operation of the fuel cell and a difference in thermal expansion occurs between the seat 8 and the manifold lid due to the temperature difference from room temperature, the seat 8, O-ring packing 9, and opening flange surface will slide and the difference in thermal expansion will be eliminated. can be absorbed. Furthermore, if the surface of the seat 8 on the opening flange side is coated with a fluorine resin material, the fluorine resin material will reduce friction and further improve the sliding properties to absorb the difference in thermal expansion. Note that when the surface of the seat 8 is coated with a fluorine resin material, the mechanical accuracy of the abutment surface between the seat 8 and the opening flange surface 3b cannot be maintained even if the O-ring packing is removed due to the sealing properties of the fluorine resin material. If the height is increased, airtightness can be maintained sufficiently and at the same time differences in thermal expansion can be absorbed by sliding. In FIG. 4, the O-ring seal 9 is attached to a seal groove on the opening flange surface of the manifold, but a seal groove may be provided in the frame-shaped seat 8 and the O-ring seal may be inserted therein.
Furthermore, it goes without saying that when a flat packing is used, it is not necessarily necessary to provide a packing groove.
Furthermore, as shown in FIG. 7, a flat rubber packing 10 may be interposed between the frame-shaped seat 8 and the battery stack 1. Since the rigidity of the seat is higher than that of the flat rubber packing, the deformation of the flat rubber packing due to thermal expansion follows the deformation of the seat due to thermal expansion. Therefore, even if there is a flat rubber gasket between the seal layer and the seat, as in the embodiment shown in FIG. 7, if there is no difference in thermal expansion between the battery stack and the seat, there will be no excessive stress on the seal layer. Does not occur.

[Effect of idea]

As mentioned above, this idea uses a frame-shaped seat made of a material whose thermal expansion coefficient is approximately the same as that of the fuel cell stack, a sealing layer applied to the side periphery of the battery stack, and an opening flange of the manifold lid. By interposing it between the cell stack and the frame-shaped seat, even if the operating temperature is higher than room temperature during fuel cell operation, for example about 200°C in a phosphoric acid fuel cell, the temperature difference between the cell stack and the frame-shaped seat can be reduced. The difference in thermal expansion due to
Therefore, the stress and strain applied to the seal layer, which has low mechanical strength and is applied to the side surface of the battery, is small. Furthermore, the frame-shaped seat, the packing, and the opening flange surface of the manifold lid absorb the difference in thermal expansion caused by the temperature difference by sliding on their contact surfaces, thereby eliminating the generation of stress. Therefore, even if the fuel cell is subjected to repeated heat cycles caused by the temperature difference between the operating temperature and the room temperature when the fuel cell is started and stopped, cracks or cracks due to fatigue of the seal layer will not occur, and sufficient airtightness can be ensured. .

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing the configuration of a fuel cell in which unit cells are stacked in a columnar manner, with Figure 1 being an exploded perspective view, Figure 2 being a plan view, and Figure 3 being the fuel cell described above. 4 is a partially enlarged perspective view showing a seal structure according to the prior art, and FIG. 4 and subsequent figures are views showing embodiments according to the present invention. FIG.
Fig. 5 is an exploded perspective view showing a state in which the battery stack and the manifold are separated from each other, and Fig. 6 is a partially enlarged perspective sectional view showing the gas seal structure between the battery stack and the manifold with a seat interposed therebetween. , FIG. 7 is a partially enlarged perspective sectional view showing another embodiment of the present invention. 1: Battery stack, 2: Oxidizing gas supply manifold, 3: Oxidizing gas exhaust manifold, 4: Fuel gas supply manifold, 5: Fuel gas exhaust manifold, 6: Seal layer, 8: Seat, 9: O Ring Patsukin.

Claims (1)

[Scope of utility model registration request] A fuel cell stack in which unit cells are stacked in a columnar manner,
A fuel cell comprising a reactant gas supply/discharge manifold having an open flange, and a sealing layer provided on a peripheral edge of a side surface of the fuel cell stack facing the open flange, the fuel cell stack and A fuel cell characterized in that a frame-shaped seat made of a material having substantially the same coefficient of expansion is interposed between the opening flange and the sealing layer.