JPS61230270A - Fuel cell - Google Patents

Abstract

PURPOSE:To prevent generation of leak current flowing from a cooling piping through refrigerate and prevent electrolytic corrosion of cooling piping by forming an insulating film which cuts electricity flow path from refrigerant on the inner surface of cooling piping. CONSTITUTION:Insulating films 27a and 27b which cut electricity flow path from refrigerant are formed on the inner surface of cooling piping 5 and 15, and on the faced surfaces of sealing materials 22a, 22b of flanges 21a, 21b and an insulator 23. Since electricity flow path between cooling water and pipings 5, 15 is cut, generation of leak current caused by electricity flow path through cooling water is prevented even if potential difference is generated between pipings 5 and 15. Therefore, the cooling pipings are prevented from electrolytic corrosion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel cell, and particularly to preventing electrolytic corrosion of cooling piping.

[Background of the invention]

The structure of a conventional fuel cell and its problems will be explained with reference to FIGS. 2 to 4.

FIG. 2 is a longitudinal sectional side view of one fuel cell.

The unit batteries 1 are stacked to form a stacked battery 2.

A combination of a cooler 3 and a cooler holder 4 is inserted into the laminated battery 2 through an insulator, and the heat generated in the laminated battery 2 during power generation is released to the outside and cooled. The cooler 3 is connected to the cooling pipe 5. Furthermore, these are the seal plates 6a.

6b, current collector plates 7a, 7b, and insulating plate 8 are combined and fixed integrally by tightening with tightening fittings 9a, 9b and tightening rod 10. Manifolds 11 for supplying and discharging reactive gases to and from the stacked battery 2 are attached to four side surfaces of the stacked battery 2 via sealing materials 12. Reaction gas supply (or discharge) piping 30 to each manifold IIK is connected to a pressure vessel 2 that houses these after interposing an insulating joint 13, respectively.
0 and is pulled out to the outside. Inside the pressure vessel 20, the cooling pipe 5 is connected to the cooling pipe 16 via an insulating joint 14.
After being disconnected from the pressure vessel 20, it is drawn out through the pressure vessel 20.

The insulating joint 14 is connected to the cooling pipe 5 as detailed in FIG.
．． 97 langes 21a, 21 formed at the ends of 15, respectively.
The sealing materials 22a, 22b and the insulating material 23 are interposed between the parts b, and the parts are connected by bolts made of an insulating material or metal bolts 24 treated with insulation.

Furthermore, an insulating support stand 16 is interposed between the clamping fitting 9b and the pressure vessel 20, and the electromagnetic energy generated in the stacked battery 2 is transferred to the lead wires 17a, 17b and the terminals 1831, 18.
b, and the potential of the lead wire 17a is applied to the manifold 11 and the cooling pipe 5 via the connecting wire 19.

During operation of the fuel cell configured as described above, reactive gas is supplied to and discharged from the stacked battery 2 through the manifold 11 through the stile and piping 30, and the electrical energy generated in the stacked battery 2 is transferred to the lead wire 17a.

17b and terminals 18a and 18b. The specific heat generated in the stacked battery 2 during this power generation is
It is transmitted to the cooling water, which is a refrigerant circulating in the cooler 3, and taken out to the outside through the cooling pipes 5 and 15, thereby cooling the stacked battery 2.

If the desired voltage cannot be obtained with one fuel cell, install a plurality of such fuel cells 31a, 31b, etc. as shown in FIG. Connected in series to form nine configurations. If the generated voltage of one fuel cell 31a is E, n1il is connected in series and from the terminal 18b of the nine final stage fuel cells 31n is n1il.
A voltage of E is obtained.

However, in such a fuel cell facility, the ground potential distribution of the terminals 18a, 18b of each fuel cell 31a... is as shown in Fig. 4(b), and the insulating joints in each fuel cell 31a... 13.14 will also be required to have a high withstand voltage.

However, cooling water flows as a refrigerant in the insulating joint 14, so even if the withstand voltage of the insulating material 23 is increased, the cooling water does not flow between the cooling pipe 5 and the cooling pipe 150 via this cooling water. Nine leakage currents flow according to the electrical resistance of . This leakage current increases as the number of fuel cells 31a connected in series increases. This leakage current has the disadvantage of eroding the inner walls of the cooling pipes 5, 150 by electrolytic corrosion, forming pinholes and thin-walled parts, and damaging them.

In addition, Japanese Patent Application Laid-Open No. 52-1363 was published on technology to prevent galvanic corrosion of cooling piping.
Although this is described in No. 8, it is not possible to prevent the occurrence of the leakage current described above.

[Purpose of the invention]

Therefore, an object of the present invention is to prevent the occurrence of leakage current flowing through the refrigerant in an insulated joint of a cooling pipe, and to prevent electrolytic corrosion of the cooling pipe due to this leakage current.

[Summary of the Invention] The present invention provides an insulating coating on the inner wall of a cooling pipe that disconnects the electrical circuit from the refrigerant, and prevents leakage current from flowing from the cooling pipe through the refrigerant by this insulating coating. It is characterized by

[Embodiments of the invention]

An example in which the present invention is applied to the cooling pipe 5.15 and its insulating joint 14 in the fuel cell described with reference to FIG. 2 will be described with reference to FIG. 1. Note that the same reference numerals are given to the same parts as in the conventional configuration, and detailed explanation thereof will be omitted.

Cooling piping 5, 150 inner wall surface and 7 langes 21a.

Insulating coatings 27a and 27b are provided on the wall surface facing the sealing material 22a* 22b and the insulating material 23 in 21b to interrupt the electric path 1 between them and the refrigerant. The insulating coatings 27a and 27b are formed by coating or molding materials such as PFA and FBP and polymerizing nine tubes.

According to the above configuration, the electric path between the cooling water, which is the refrigerant flowing through the cooling pipes 5 and 15, and these cooling pipes 5 and 15 is blocked by the insulating coatings 27a and 27b.
Even if a potential difference occurs between the cooling pipes 5 and 150, a leakage current using the cooling water as an electric path will not occur as in the conventional case, and therefore the cooling pipes 5 and 15 will not be eroded by electrolytic corrosion.

It is not necessary to provide these insulating coatings 27B, 27b [inside the inner wall of the cooling pipe 5゜15 over the entire length; it is sufficient to provide them within a range that increases the electrical resistance of the cooling water and prevents electrolytic corrosion. A similar effect can be obtained by simply providing it on one side of the pipe 5°15.

〔Effect of the invention〕

As described above, the present invention provides an insulating coating on the inner wall of the cooling pipe to cut off the electrical circuit with the refrigerant, thereby preventing leakage current from flowing from the cooling pipe through the refrigerant. Can prevent eclipse.

[Brief explanation of drawings]

Fig. 1 is a vertical side view of an insulated joint of a cooling pipe in a fuel cell according to the present invention, Fig. 2 is a longitudinal side view of a conventional fuel cell, and Fig. 3 is a longitudinal side view of an insulated joint of a cooling pipe. , Fig. 4 (electrical connection diagram), (b) is a potential distribution characteristic diagram. 2... Laminated battery, 3... Cooler, 5.15... Cooling piping, 20... Pressure. Container, 27a, 27b...insulating coating.

Claims (1)

[Claims] 1. A stacked battery configured by stacking unit batteries, a cooler provided on the stacked battery, a pressure vessel housing these, and a battery drawn out from the cooler, penetrated through the pressure vessel, and drawn out to the outside. What is claimed is: 1. A fuel cell comprising a cooling pipe that is separated by an insulating joint midway through the cooling pipe, characterized in that an insulating coating is provided on the inner wall of the cooling pipe to cut off an electrical circuit with a refrigerant.