JPH04242076A - Fuel cell - Google Patents

Abstract

PURPOSE:To secure an electric insulating creeping surface not contaminated by the phosphoric acid, and to prevent to earth a cell main body even though the phosphoric acid oozes, by providing a projecting edge projecting from the outer end of a manifold to the outer side on a protective body, in a phosphoric acid type fuel cell. CONSTITUTION:By forming a projecting edge 3c' from the outer end 3a'' of the flange 3a' of a manifold main body 3a at the protective body 3b of a manifold 3, a space 8 for accumulation surrounded by a cell main body 1, the end face 5b of a seal member 5, and the projecting edge 3c' is formed, and at the same time, a sound electric insulating creeping surface which is never contaminated by the phosphoric acid is secured on the side opposite to the side facing the cell main body 1. Consequently, even though the phosphoric acid oozes, the cell main body 1 is never earthed, and a stable operation can be carried out for a long period.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a fuel cell main body formed by stacking a plurality of unit cells each consisting of a matrix supporting an electrolyte and a pair of electrodes sandwiching the matrix, and The present invention relates to a fuel cell comprising a manifold arranged on the side of a fuel cell body for supplying and discharging fuel gas and oxidant gas, respectively, and particularly relates to a fuel cell equipped with a manifold configured to ensure stable operation over a long period of time. . [0002] A fuel cell has a matrix supporting an electrolyte, and a pair of porous holes sandwiching the matrix and having a fuel gas flow path and an oxidant gas flow path through which fuel gas and oxidant gas flow, respectively. A fuel cell main body is constructed by stacking a plurality of unit cells consisting of oxidizing gas diffusion electrodes, and a fuel gas and an oxidant gas are supplied to the fuel cell main body to cause an electrochemical reaction and direct current electricity is generated from both electrodes. It is designed to occur. For example, in a phosphoric acid fuel cell, phosphoric acid is used as the electrolyte, hydrogen-rich reformed gas obtained by steam reforming a hydrocarbon fuel is used as the fuel gas, and air is used as the oxidant gas. It operates at a temperature of approximately 200°C for high efficiency. FIG. 3 is an exploded perspective view showing an example of the structure of a phosphoric acid fuel cell according to the prior art. In FIG. 3, 1 is a fuel cell main body (hereinafter abbreviated as the cell main body), which is held between end plates 2 provided at the upper and lower ends.
A fuel inlet manifold 3 and a fuel outlet manifold 4 are provided on one side surface facing the battery body 1 via a sealing material 5, respectively, and are configured to supply and discharge fuel gas to the battery body 1. Further, on the other side facing the battery body 1, an oxidizing gas inlet manifold 6 and an oxidizing gas outlet manifold 7 are provided via a sealing material 5, respectively, to supply and discharge oxidizing gas to the battery body 1. It is configured like this. By the way, the above phosphoric acid fuel cell
When operating at 0° C., phosphoric acid is carried out of the cell body 1 by the fuel gas and oxidant gas. On the other hand, since the manifold is made of metal because it needs to have sufficient mechanical strength, it is necessary to take measures to protect the metal manifold from the highly corrosive properties of high-temperature phosphoric acid. For this purpose, Japanese Patent Application Laid-Open No. 63-13278 has already been proposed. FIG. 4 is a cross-sectional view showing a manifold 3 as a representative example of the structure of a manifold according to the prior art. Manifolds 4, 6 and 7 also have the same structure. In FIG. 4, 3a is the manifold body, which is made of metal to provide sufficient mechanical strength. 3f is a protector for the manifold body 3a that protects the manifold body 3a from the strong corrosive properties of phosphoric acid, and is made of plastic (e.g. fluorine resin) or synthetic rubber (e.g. fluorine rubber) that has heat resistance, acid resistance and electrical insulation properties.
Made in Japan. In order to airtightly seal between the manifold 3 and the battery body 1 via the sealing material 5, a flange 3a' is formed at the part where the sealing material 5 is pressurized, and the outer end 3a'' of the flange is located at the position of the sealing material. The position is almost the same as the position of the outer end 5b of the fuel gas.
A fuel gas supply system such as a fuel reformer (not shown) is connected to 4, and an oxidizing gas supply system such as an air supply blower (not shown) is connected to manifolds 6 and 7 for supplying and discharging oxidizing gas via metal piping (not shown). It is electrically grounded. The electrical insulation of the battery body 1 from the ground is performed by the sealing material 5 and the protector. [0006] In the phosphoric acid fuel cell according to the prior art described above, the phosphoric acid impregnated and supported in the matrix is exposed to the fuel gas and oxidizing gas during operation of the fuel cell. When supplied, the pressure exerted by these gases is applied to a large surface of the matrix, and a small amount may flow out of the matrix. Further, the leaked phosphoric acid oozes out if there is a seal failure in the seal formed by the manifold and the sealing material. When the outer end of the sealing material and the outer end of the holder are wetted by the seeped phosphoric acid, the battery main body and the metal manifold main body become electrically conductive. As mentioned above, the manifold body is metal-piped and grounded, so as a result, the battery body is grounded at the point where the phosphoric acid oozes out.
There is a risk that the fuel cell will not be able to continue operating. A similar problem may also occur if dust accumulates on the outer ends of the sealing material and the holder. The present invention was developed in view of the problems of the prior art described above, and its purpose is to provide stable operation for a long period of time without the battery body being grounded even if phosphoric acid oozes out or dust accumulates. An object of the present invention is to provide a fuel cell equipped with a manifold capable of performing the following steps. Means for Solving the Problems The above-mentioned objects of the present invention are as follows: 1) A pair of fuel gas flow passages and an oxidant gas flow passage through which fuel gas and oxidant gas flow, respectively. A fuel cell main body is formed by stacking a plurality of unit cells in which a matrix supporting an electrolyte is arranged between gas diffusion electrodes, and fuel gas and oxidant gas are supplied and discharged to and from the gas diffusion electrodes on the sides thereof, respectively. A manifold having a protector made of plastic or synthetic rubber having heat resistance, acid resistance, and electrical insulation is arranged inside the fuel cell, and a sealing material is used to seal between the manifold and the fuel cell main body. In the fuel cell according to the present invention, a projecting edge is formed on the protector outwardly from an outer end of the flange of the manifold,
2) In the means described in item 1 above, the projecting edge portion is formed parallel to the sealing surface of the sealing material;
3) In the means described in item 1 above, this is achieved by forming the projecting edge in a direction perpendicular to the sealing surface of the sealing material. [Operation] In the present invention, by adopting the above-described structure, a space is formed between the protector and the fuel cell body for phosphoric acid and dust to accumulate, and at the same time, the protector is free from phosphoric acid and dust. It is now possible to secure creeping surfaces for electrical insulation that will not be contaminated. This ensures that even if phosphoric acid oozes out of the seal, it remains in the deposition space. On the other hand, the electrically insulating creeping surface is not contaminated by phosphoric acid, and therefore a healthy electrically insulating creeping surface having the required creeping distance can be maintained. As a result, there is no electrical continuity between the battery body and the manifold body. This also applies to dust. [Embodiments] Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a manifold according to an embodiment of the present invention. Components that are the same as those in the conventional example shown in FIG. 4 are given the same reference numerals, and their explanations will be omitted. The difference between FIG. 1 and FIG. 4 lies in the shape of the outer end portion of the protector. In Fig. 1, the outer end 3a'' of the flange portion 3a' of the manifold body 3a
A projecting edge 3c' is formed to extend outward from the flange 3b' of the protector 3b in parallel with the sealing surface 5a of the sealing material 5, and from the outer end 3a'' of the flange of the manifold body to l1. The edge of the protrusion of the protector at a distance of 3
2 is a cross-sectional view of a manifold according to a different embodiment of the present invention. Components that are the same as those in FIGS. 2 is different from FIGS. 1 and 4 in the shape of the outer end portion of the protector. In FIG. A projecting edge 3e' is formed extending from the flange 3d' of the protector 3d in a direction perpendicular to the sealing surface 5a of the sealing material 5, and a protruding edge 3e' extends from the outer end 3a'' of the flange of the manifold body to l2.
The end portion 3e'' of the protruding edge of the protector is provided at a distance of .
For example, in the case of the protector 3b shown in FIG. 1, phosphorus exuding from the sealing surface 5a of the sealing material 5 is present in a space surrounded by the end face of the battery body 1, the end face 5b of the seal 5, and the protruding edge 3c' of the protector. A deposition space 8 for accumulating acid is formed, and the surface of the protruding edge 3c' of the protector opposite to the side facing the battery body 1 is free from staining due to oozing phosphoric acid.
A healthy electrically insulating creepage surface having a creepage distance l1 for ensuring electrical insulation between the battery body 1 and the manifold body 3a can be maintained. This also applies to dust. Moreover, in the case of the protector 3d according to FIG.
A space 8' for depositing phosphoric acid seeped from the sealing surface 5a of the sealing material 5 is formed on the upper surface of the end surface 5b of the sealing material 5 and the projecting edge 3e' of the protector.
The lower surface of e' is not contaminated by oozing phosphoric acid, and a healthy electrically insulating creepage surface with a creepage distance l2 to ensure electrical insulation between the battery body 1 and the manifold body 3a can be maintained. . This also applies to dust. [0016] According to the present invention, as described above, by providing a protrusion on the protector provided inside the manifold on the outside of the outer end of the flange of the manifold, phosphoric acid seeped out from the seal portion can be prevented. The surface of the flange opposite to the side facing the battery body or the lower surface of the flange is free from seepage. It is possible to maintain a healthy electrically insulating creepage surface with the required creepage distance without being contaminated by phosphoric acid or dust. This prevents electrical connection between the battery body and the manifold body even if phosphoric acid oozes out from the seal or dust accumulates.
The battery body is no longer electrically connected, and therefore the battery body can operate stably for a long period of time without being grounded.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a manifold according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a manifold according to different embodiments of the invention.

[Figure 3] Exploded perspective view of a conventional phosphoric acid fuel cell

[Figure 4
] Cross-sectional view of a conventional manifold

[Explanation of symbols]

1 Fuel cell body 3 Manifold 3a Manifold body 3b Protective body 3c’ ridge 5 Seal material

Claims (3)

[Claims] Claim 1: A plurality of unit cells each having a matrix supporting an electrolyte arranged between a pair of gas diffusion electrodes each having a fuel gas flow path and an oxidant gas flow path through which fuel gas and oxidant gas flow, respectively. They are stacked to form a fuel cell main body, the sides of which supply and discharge fuel gas and oxidant gas to the gas diffusion electrode, respectively, and the inside made of plastic or synthetic rubber that has heat resistance, acid resistance, and electrical insulation properties. In a fuel cell configured such that a manifold having a protector is disposed and a sealing material is used to seal between the manifold and the fuel cell main body, the protector has a protrusion outward from the outer end of the flange of the manifold. A fuel cell characterized in that an edge is formed. 2. The fuel cell according to claim 1, wherein the projecting edge is formed parallel to a sealing surface of the sealing material. 3. The fuel cell according to claim 1, wherein the projecting edge is formed in a direction perpendicular to a sealing surface of the sealing material.