JPS61285677A - Fuel cell - Google Patents

Abstract

PURPOSE:To obtain a highly safe fuel cell which has high performance and long life and in which the airtightness between the cell stack and the manifold can be sufficiently maintained by using seal packings each of which is folded in at least two. CONSTITUTION:Seal packings 12 and 13 each formed by folding a thin belt-like material are placed on the surfaces of a fluorine resin plate 9 which is placed between the outer surface of a cell stack 6 and the end section 7 of a manifold 8. The seal packing 12 placed between the outer surface of the cell stack 6 and the fluorine resin plate 9 is folded in four. The seal packing 13 placed between the end section 7 of the manifold 8 and the fluorine resin plate 9 is folded in two. Due to the above structure, there is no possibility for reaction gas to leak through the resin layer of the fibrous seal packing material and the airtightness between the cell stack 6 and the manifold 8 is sufficiently maintained. Accordingly, there is no possibility that the output of the fuel cell is reduced or its safety is spoiled.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fuel cell, and in particular improves the structure of a seal between a cell stack and a reactant gas supply and discharge manifold arranged on the outer peripheral surface of the cell stack. related to fuel cells.

[Technical background of the invention]

Fuel cells are conventionally known as devices that directly convert energy contained in fuel into electrical energy. This fuel cell usually has a pair of porous electrodes sandwiched between an electrolyte layer impregnated with an electrolyte, and a fuel gas such as hydrogen is brought into contact with the back surface of one electrode, and oxygen gas or other gas is brought into contact with the back surface of the other electrode. The oxidizing gas of Electrical energy can be extracted with high conversion efficiency.

FIGS. 2 and 3 show an example of the structure of this type of fuel cell in a longitudinal cross-sectional view and a plan view, respectively, and FIG. 4 is a partial cross-sectional view showing the details of the seal part in the same fuel cell. This is shown in . In the figure, 1 is a unit battery,
This unit cell 1 is formed by arranging a pair of porous electrodes made of a carbon material to which a catalyst is added, sandwiching an electrolyte layer in which a matrix is impregnated with an electrolytic solution such as phosphoric acid. An interconnector 2 is arranged on the back side of both electrodes of the unit cell 1, and flow paths for fuel gas and oxidant gas are formed between the unit cell 1 and the interconnector 2.

This interconnector 2 is a plate with ribs made of a mixed bond of graphite and thermosetting resin. A combination of such a unit cell 1 and an interconnector 2 is used as one unit battery, and a plurality of such unit batteries are stacked. A current collecting plate 3 is disposed above and below the current collector plate 3, and a clamping plate 5 is disposed with an insulating spacer 4 interposed therebetween, and is tightened using metal fittings or the like to form a prismatic cell stack 6. Gas flow ports are provided on the outer circumferential surface of the cell stack 6, and mounting edges 7 for attaching to the cell stack 6 are formed on the four outer circumferential surfaces thereof. Four metal manifolds 8 for supplying and discharging reaction gas are attached via sealing materials formed between them. These manifolds 8 form a reaction gas flow path between them and the outer peripheral surface of the cell stack 6, and the sealing material maintains airtightness within the manifold 8 and further seals the cell stack 6 and the manifold 8. The purpose is to maintain safety and corrosion resistance by electrically insulating between the cell stack 6 and the manifold 8, and due to the difference in thermal expansion between the cell stack 6 and the manifold 8, the seal packings 10 and 11 are sandwiched between them. It is configured to slide on the surface of the fluororesin plate 9, and is designed to prevent excessive thermal stress from occurring in the cell stack 6 and manifold 8.

[Problems with the background art] By the way, in such a fuel cell, the cell stack 6
Maintaining electrical insulation and airtightness between the and manifold 8,
Alternatively, the sealing material used to absorb the difference in thermal expansion between the cell stack 6 and the manifold 8 must be able to withstand these usage conditions. on the other hand,
The operating temperature of a fuel cell is approximately 170°C to 200°C in terms of reaction theory.
Since the sealing material reaches extremely high temperatures, a fluororesin-based material is generally used as the sealing material.In particular, the sealing portion has a sliding function to absorb the difference in thermal expansion between the cell stack 6 and the manifold 8. Since this is required, a highly flexible and strong fibrous fluororesin is used for the seal packings 10 and 11 arranged on both sides of the fluororesin plate 9. For example, the product name of this material is GORE-TEX (Japan Vore-Tex Co., Ltd.).
etc.

However, when such m-string-shaped fluororesin is used in the seal packings 10 and 11 in a single layer state as shown in FIG. 4, reaction gas leaks through the resin layer because it is fibrous. In particular, if the tightening pressure of the sealing material decreases due to temperature changes in the cell stack 6 or deformation of the sealing material over time, the amount of leakage of reactant gas will increase, making it impossible to maintain airtightness and causing damage to the fuel cell. There is a risk of reducing output or impairing safety.

[Purpose of the invention]

The present invention was made to solve the above-mentioned problems, and its purpose is to reduce pressure drop, etc. due to sliding due to the difference in thermal expansion between the cell stack and the manifold, and tightening due to aging deformation of the sealing material. An object of the present invention is to provide a high-performance, long-life, and highly safe fuel cell that can sufficiently maintain airtightness between a cell stack and a manifold even under such conditions.

[Summary of the invention]

In order to achieve the above object, the present invention forms a prismatic cell stack by layering a plurality of unit cells, interconnectors, etc. each having a pair of porous electrodes sandwiching an electrolyte layer impregnated with an electrolyte. A manifold for supplying and discharging a reactant gas with a reactant gas flow path formed between the outer circumferential surface of the cell stack and the outer circumferential surface of the cell stack is disposed on the four outer circumferential surfaces of the cell stack, and In a fuel cell in which a combination of a fluororesin plate and a tiAH seal packing is inserted as a sealing material between the parts, the seal packing is bent at least once or more to form a plurality of layers, so that a reaction can be achieved. It is characterized by preventing gas from leaking from the seal packing layer.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention shown in FIG. 1 will be described. Note that the same parts as in FIG. 4 are given the same reference numerals, and the explanation thereof will be omitted, and only the different parts will be described here.

FIG. 1 is a partial sectional view showing an example of the configuration of a seal portion in a fuel cell according to the present invention.

In other words, FIG. 1 shows the sealing gaskets shown in FIG. The seal packings 12 and 13 are made of a plurality of layers formed by bending a single thin band-shaped material made of the same material. In this example, the seal packing 12 inserted between the outer circumferential surface of the cell stack 6 and the fluororesin plate 9 is formed in four folds, and the attachment edge 7 of the manifold 8 and the fluororesin plate 9 are The seal packing 12 inserted between the two is folded in two.

In such a fuel cell, since the seal portion is constructed by bending a single thin strip-shaped material to form the seal packings 12 and 13 in multiple layers, l! No leakage of reactant gas occurs through the resin layer of the fibrous seal backing material. In addition, even if the pressure of the sealing material decreases due to temperature changes in the cell stack 6 or deformation of the sealing material over time, the leakage path for the reactant gas is long, making it extremely difficult for leaks to occur. Even if a leak were to occur, the amount of reaction gas leaked would be such that it would not interfere with fuel cell operation. As a result, the airtightness between the cell stack 6 and the manifold 8 can be sufficiently maintained, and there will be no reduction in the output or safety of the fuel cell.

As described above, in the fuel cell of this embodiment, the cell stack 6
The structure is such that the manifold 8 is attached to the outer circumferential surface of the cell stack 6 by combining the fluororesin plate 9 and seal packings 12 and 13 formed in multiple layers by bending the fluororesin plate 9 to form a sealing material. Even under conditions such as pressure drop, sliding due to the difference in thermal expansion between the cell stack and tightening due to aging deformation of the sealing material maintains sufficient airtightness of the reactant gas between the cell stack and the manifold, and the fuel cell This is highly effective in maintaining properties and safety.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be similarly implemented in the following manner.

For example, the number of times the seal packings 12 and 13 are bent may be selected depending on the material of the seal packing, and the above embodiment shows a case where a commercially available material as described in FIG. 4 is used. It is completely unrelated. In short, the seal packings 12 and 13 may be formed by bending them into a plurality of layers.

In addition, the present invention can be modified and implemented in various ways without departing from the gist thereof.

(Effects of the Invention) As explained above, according to the present invention, a prismatic structure is formed by stacking a plurality of unit cells, interconnectors, etc. each having a pair of porous electrodes sandwiching an electrolyte layer impregnated with an electrolyte. A reactant gas supply in which a cell stack is formed, and reactant gas channels are formed between the four outer peripheral surfaces of the cell stack and the outer peripheral surface of the cell stack.

A discharge manifold is arranged, and a fluororesin plate is placed between the outer peripheral surface of the cell stack and the peripheral edge of the manifold! In a fuel cell in which a combination of seal packings of the form [shaped] are inserted as a sealing material, the seal packings are bent at least once to form a plurality of layers, so that thermal expansion between the cell stack and the manifold is reduced. Sliding caused by differences and tightening caused by deformation of the seal material over time are extremely high-performance and long-life, capable of maintaining sufficient airtightness between the cell stack and manifold even under conditions such as pressure drop. A fuel cell with high safety and reliability can be provided.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing one embodiment of the present invention, FIGS. 2 and 3 are a vertical sectional view and a plan view showing the structure of a fuel cell, respectively, and FIG. 4 is a partial sectional view showing an embodiment of the present invention. FIG. 3 is a partial cross-sectional view showing details of a seal portion of the fuel cell. DESCRIPTION OF SYMBOLS 1... Unit battery, 2... Interconnector, 3... Current collector plate, 4... Insulating spacer, 5... Tightening plate, 6...
・Cell stack, 7... Mounting edge, 8... Manifold, 9... Fluororesin plate, 10.11, 12.13
... Seal Patsukin. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A prismatic cell stack is formed by stacking a plurality of unit cells, interconnectors, etc. in which a pair of porous electrodes are arranged with an electrolyte layer impregnated with an electrolyte layer sandwiched between them, and the cell stack is attached to the outer four sides of the cell stack. A manifold for supplying and discharging a reaction gas with a reaction gas flow path formed between the outer peripheral surface of the cell stack and a fluororesin plate and a fibrous resin plate is disposed between the outer peripheral surface of the cell stack and the peripheral edge of the manifold. What is claimed is: 1. A fuel cell comprising a combination of seal packings inserted as a sealing material, characterized in that the seal packings are bent at least once to form a plurality of layers.