JPH07226218A - Fuel cell electrical isolation device - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain an electrical insulation device for a fuel cell that can be used regardless of the operating temperature and operating pressure of the fuel cell. [Structure] An insulating ring 1a inserted between pipe flanges at a connecting portion of a pipe, an insulating outer cylinder 1b coupled to an outer diameter side of the insulating ring 1a and fitted on the outer side of an upstream pipe, and an inner diameter of the insulating ring 1a. Since the insulating flange 1 including the insulating inner cylinder 1c that is connected to the side and extends inside the downstream pipe 7 is provided, and both the pipe flanges 6a and 7a are tightened by the plurality of insulated tightening bolts 2 and nuts 3. The electrical insulation of the cooling water and the electrical insulation of the pipe flange can be maintained regardless of the operating pressure and operating temperature of the fuel cell.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrical insulation device for a water-cooled phosphoric acid fuel cell.

[0002]

2. Description of the Related Art A unit cell constituting a fuel cell is constructed by arranging an oxidizer electrode and a fuel electrode with an electrolyte sandwiched therebetween. Each unit cell is composed of an electrode coated with a platinum catalyst on the surface of a thin porous carbon plate, a matrix that holds phosphoric acid in the electrolyte, and a separator that separates the unit cell, and the battery stack is formed between these unit cells and between them. It is configured by stacking with the inserted cooling plate. In a fuel cell, power is generated by reacting a fuel gas with an oxidant gas.

Generally, it is desirable that the average temperature of the phosphoric acid fuel cell during power generation is 140 ° C. to 190 ° C. The reason is that the temperature of more than 200 ° C. causes the heat deterioration of the electrode constituent material, and the temperature of less than 140 ° C. causes the decrease of the generated voltage due to the wetting phenomenon of the electrode due to the condensate of the reaction product. The electrical insulation of a water-cooled phosphoric acid fuel cell is generally done by electrically insulating it with an electrical insulator in the cooling water piping system. The electrical insulation resistance between the battery and ground is maintained at a specified value. Pure water having a large electric resistance is used as the cooling water.

[0004]

In order to secure the electric insulation resistance of the pipe, the length of the electric insulating hose made of an electric insulator is required based on the inner diameter of the cooling water pipe and the electric conductivity of the water. Therefore, a long cylindrical insulator made of an insulating material is required. Further, it is also necessary to electrically insulate a fastening tool such as a bolt for connecting a pipe made of metal in order to hold an insulator to be connected. Increase in cooling water volume and pipe diameter of cooling water pipes in order to supply cooling water evenly in the plane direction and stacking direction as cell area increases, current density increases, and generation voltage increases. Since the electrical insulation hose to be connected to the cooling water piping system lacks strength at the connection part, it is difficult to use the electrical insulation hose due to the operating temperature, operating pressure and insulation distance of the fuel cell. Has become.

An object of the present invention is to provide an electrical insulation device for a fuel cell which can be used regardless of the operating temperature and operating pressure of the fuel cell.

[0006]

[MEANS FOR SOLVING THE PROBLEMS] In a fuel cell in which cooling water is circulated through an electrode of a cell stack formed by stacking a plurality of unit cells through a pipe, the fuel cell is inserted between pipe flanges of a connecting portion of the pipe. An insulating ring, an insulating outer cylinder coupled to the outer diameter side of the insulating ring, and fitted on the outer side of the upstream pipe, and an inner diameter side of the insulating ring coupled to the insulating outer cylinder in the opposite direction to the downstream pipe. The above object is achieved by providing an insulating flange composed of an insulating inner cylinder extending inward, and fastening both piping flanges with a plurality of insulated tightening bolts and tightening nuts.

If the insulating flange is made of a fluororesin, it is suitable for welding to form the insulating flange.

Further, an annular reinforcing ring is provided on the outer circumference of the insulating inner cylinder, and if this reinforcing ring is made of fluororesin, it is suitable for mounting the reinforcing ring.

[0009]

According to the present invention, the insulating outer cylinder fitted on the outer circumference of the upstream pipe, the insulating inner cylinder inserted inside the downstream pipe, and the insulating ring connecting the insulating outer cylinder and the insulating inner cylinder to each other. Since the insulating flange is attached to the joint of the cooling water pipe, the insulating material is used regardless of the operating pressure of the fuel cell and can withstand the operating temperature, so that it can be used regardless of the operating temperature. The length necessary for the electrical insulation of the cooling water can be kept in the insulating inner cylinder, and the electrical insulation distance of the pipe can be kept in the insulating outer cylinder. If the insulating flange is made of fluororesin, the components can be formed by welding the components to each other. Further, if a reinforcing ring is attached to the outer periphery of the insulating inner cylinder of the insulating flange, the insulating inner cylinder can be reinforced against the contraction phenomenon of the cooling water.

[0010]

1 is a sectional view showing a connecting portion of a pipe using an electric insulation device according to an embodiment of the present invention. In FIG. 1, arrows indicate the flow direction of the cooling water, and an electrical insulating device is attached between the pipe flange 6a of the upstream pipe 6 and the pipe flange 7a of the downstream pipe 7. Insulation ring 1 inserted between the pipe flanges 6a and 7a at the pipe connection
a, an insulating outer cylinder 1b which is coupled to the outer diameter side of the insulating ring 1a and fits on the outer side of the upstream pipe 6, and an inner diameter side of the insulating ring 1a which is coupled in the opposite direction to the insulating outer cylinder 1b. 7, an insulating flange 1 is provided which is composed of a cylindrical insulating inner cylinder 1c having an annular reinforcing rib 1d. To insulate the electric circuit of the water inside the pipe, the length of the insulating inner cylinder is set to the length required for the electric insulation resistance of water. Piping flange 6a, 7a
The electrical insulation distance between them is maintained by the length of the insulating outer cylinder 1b. The insulating ring 1a, the insulating outer cylinder 1b, the insulating inner cylinder 1c, and the reinforcing ring 1d are each made of polyfluoroethylene (trade name: Teflon).
To use. This is because fluororesin has excellent heat resistance, chemical resistance, and electrical insulation and is easy to weld. When the insulating flange 1 is inserted into the pipe, the inner diameter of the downstream pipe 7 becomes narrower and the flow of the cooling water causes a contraction phenomenon, and the insulating inner cylinder 1c tends to move to the center. A plurality of reinforcing rings 1d made of resin are attached by welding. The insulating inner cylinder 1c may be thickened instead of the reinforcing rib 1d. A plurality of tightening bolts 2 are tightened with tightening nuts 3 in order to tighten the pipe flanges 6a and 7a. To insulate the tightening bolt 2, an insulating pipe 4 is attached to the outer circumference of the tightening bolt 2, and an insulating seat 5 is used for the piping flange 7a.

Insulating ring 1 for sealing cooling water
Gaskets 8 were inserted between a and the piping flange 6a and between the insulating ring 1a and the piping flange 7a. Furthermore, in order to maintain the gasket surface pressure, it is desirable to insert a spring (not shown) between the tightening flange and the piping flanges 6a, 7a. According to the present invention, by inserting the insulating flange 1 in the middle of the cooling water pipe and tightening it with the insulated tightening bolt 2 and the tightening nut 3, the electrical insulation resistance required for the cooling water and the space between the pipe flanges are increased. The electrical insulation distance can be maintained, and the pipe flanges 6a and 7a can be electrically insulated.

[0012]

According to the present invention, an insulating flange, an insulating inner cylinder, and an insulating outer cylinder constitute an insulating flange, and the insulating flange is inserted into a connection portion of a cooling water pipe to insulate the pipe flange. Combined with the tightening bolts and nuts,
It is possible to maintain the electrical insulation of the cooling water and the electrical insulation distance between the pipe flanges, as well as the electrical insulation of the tightening bolts.
According to the present invention, the electrical insulation of the cooling water pipe can be maintained regardless of the operating pressure and operating temperature of the fuel cell.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a connecting portion of a pipe using an electric insulation device for a fuel cell according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 1 Insulation Flange 1a Insulation Ring 1b Insulation Outer Cylinder 1c Insulation Inner Cylinder 1d Reinforcing Rib 2 Tightening Bolt 3 Tightening Nut 4 Insulation Pipe 5 Insulating Seat 6 Upstream Piping 6a Piping Flange 7 Downstream Piping 7a Piping Flange 8 Gasket

Claims (3)

[Claims] 1. A fuel cell in which cooling water is circulated through a pipe to an electrode of a cell stack formed by stacking a plurality of unit cells, and an insulating ring inserted between pipe flanges at a connecting portion of the pipe, An insulating outer cylinder coupled to the outer diameter side of the insulating ring and fitted on the outer side of the upstream pipe, and an insulating outer cylinder coupled to the inner diameter side of the insulating ring in a direction opposite to the insulating outer cylinder and extending inside the downstream pipe. An electric insulating device for a fuel cell, comprising: an insulating flange composed of an inner cylinder; and both pipe flanges fastened by a plurality of insulated tightening bolts and tightening nuts. 2. The electric insulating device for a fuel cell according to claim 1, wherein the insulating flange is made of fluororesin. 3. The electric insulation device for a fuel cell according to claim 1, wherein an annular reinforcing ring is provided on the outer periphery of the insulating inner cylinder, and the reinforcing ring is made of fluororesin. .