JPH0160907B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to electrical insulation of a fuel cell, and particularly to an electrical insulation structure of a stacked fuel cell having a high voltage output and having a plurality of stacked unit cells.

[Background of the invention]

Conventionally, as this type of stacked fuel cell, one having the configuration shown in FIG. 1 is known. FIG. 1a is a front sectional view, and FIG. 1b is a plan sectional view. As shown in FIG. 1, a plurality of power generation sections 2 each formed by stacking a plurality of unit batteries 1 are further stacked in a plurality of stages, and a cooler 3 is installed between each power generation section 2 in order to extract heat loss from the power generation section 2 to the outside. A combination of a cooler holder 4 and a cooler holder 4 are inserted and arranged. A sealing plate 5, current collecting plates 6a, 6b, and insulating plate 7 are arranged in this order on both upper and lower sides, and the whole is fixed by tightening with tightening fittings 8a, 8b and a tightening rod 9. A manifold 10 that supplies or discharges a reactive gas to the power generating section 2 is provided so as to surround each side of the power generating section 2 via a sealing material 11 that prevents leakage of the reactive gas. This manifold 10 is connected to a reaction gas supply/discharge pipe connected to a pressure vessel 13 via an insulating joint 12a, so that reaction gas can be supplied or discharged from the outside via this pipe. Similarly, an insulating joint 12b is provided between the cooler 3 and a refrigerant pipe communicating with the outside of the pressure vessel 13. Furthermore, an insulating support stand 14 is provided on the clamping fitting 8b and the pressure vessel 13. In this way, the pressure vessel 13 that is at ground potential, the power generation section 2 or manifold 10 that is at high potential, the cooler 3, and the clamping fittings 8
b are electrically insulated from each other. The electrical energy generated in the power generation section 2 is transferred to the lead wire 15.
a, 15b, and bushing type terminals 16a, 1
It is adapted to be taken out to the outside via 6b. Further, the manifold 10, the cooler 3, and the clamping fittings 8a, 8b are connected to the lead wire 1 by a connecting wire 19.
5b, and is maintained at the same potential as one electrode potential of the stacked battery.

However, with the above configuration, the unit battery 1
As the number of stacked layers increases, as shown in Figure 2,
The potential difference between the lead wires 15a and 15b is N·E ₀ where E ₀ is the generated voltage per unit battery and N is the number of stacked layers, and increases in proportion to the number of layers N.
For example, when generating a DC output of 250kW, N.
E ₀ is a high potential difference of about 500V. Therefore, in order to prevent short-circuiting of N unit batteries due to this potential difference,
A sealing material 11 provided between the manifold 10 and the power generation section 2 or the sealing plate 5 also serves as an insulating member. On the other hand, as shown in Figure 3,
An insulating material 17 as an insulating member is also provided between the cooler 3 and the cooler holder 4. The dielectric strength of these sealing materials 11 and insulating materials 17 is sufficient N・E ₀
must satisfy. However, when phosphoric acid is used as the electrolyte in the unit battery 1, or when the operating temperature during battery operation is high, around 200°C, the insulation of the sealing material 11 or the insulating material 17 may be damaged by acid or heat. may deteriorate, or the thickness of the sealing material 11 may decrease due to thermal deformation, or cracking may occur, making it impossible to maintain the initial dielectric strength voltage and causing dielectric breakdown due to the potential difference N・E ₀ . There is. For example, if dielectric breakdown occurs in the sealing material 11, a short circuit will be formed in the stacked unit batteries 1 via the manifold 10 and the connecting wire 19, and the output of the battery will decrease or become zero, making it impossible to operate. It has the disadvantage of getting used to it.

Therefore, a method can be considered in which the thickness of the sealing material 11 and the insulating material 17 is increased to prevent a decrease in dielectric strength voltage due to deterioration or thermal deformation. However, increasing the thickness of these members is not only uneconomical, but also has the drawback that increasing the thickness of the insulating material 17 deteriorates heat conduction between the cooler 3 and the unit battery 1, reducing cooling performance. arise.

Furthermore, the conventional electrical insulation structure has the disadvantage that the maximum number of stacked layers _Nnax , that is, the maximum output voltage, is limited due to limitations on the thickness of the insulating member and deterioration of its dielectric strength.

[Object of the invention] An object of the invention is to reduce the thickness of an insulating member,
Moreover, it is an object of the present invention to provide a stacked fuel cell having an electrically insulating structure that can maintain sufficient insulation even if the dielectric strength decreases due to deterioration or thermal deformation, and can increase the number of stacked layers.

[Summary of the invention]

The present invention electrically connects one electrode of the stacked central unit cells to the manifold and the cooler to have the same potential, thereby reducing the potential difference applied to the insulating member to the maximum output voltage. By reducing the thickness to 1/2 or less, the thickness of the insulating member is reduced, the required dielectric strength is reduced, and the number of stacked layers is increased.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on examples.

FIG. 4 shows an overall configuration diagram of an embodiment of the present invention, and FIG. 4 a and b are a front sectional view and a plan sectional view, respectively. Same functions as the conventional example shown in Figure 1.
Components having the same configuration are given the same reference numerals and description thereof will be omitted.

In FIG. 4a, the difference from the conventional example shown in FIG. and that the connecting wire 19 that brings the lead wire 15b and the manifold 10 to the same potential shown in FIG. 1a is removed.
As shown in FIG. 5, the manifold 10 is connected from the lead 15b side to the + electrode of the N _-th unit battery 1 by a connecting wire 19a.
0, the cooler 3, and the clamping fitting 8a are connected by connection lines 19b and 19c, respectively.

Since it is structured in this way, the
N From the _first figure, the maximum potential difference applied to the lower insulating members, that is, the sealing material 11 or the insulating material 17, the insulating plates 7, 18, etc., is N ₁ E ₀ , and the same applies to the upper insulating members. The maximum potential difference is (N
-N ₁ ) is reduced to E ₀ . At this time, the maximum potential difference
N ₁ E ₀ or (N-N ₁ ) E ₀ is set so that it is less than the minimum spark voltage of gas based on Patsien's law.
Select N ₁ . This minimum spark voltage is, for example, 330 V in air as a reaction gas, and 330 V in hydrogen gas.
270V, and 250V in the nitrogen gas inside the pressure vessel 13. In general, N ₁ = (N-N ₁ ) or N ₁
If =1/2N is selected, the maximum potential difference applied to the upper or lower insulating member becomes the same, and the dielectric strength voltage on both sides can be minimized. As a specific example, considering a stacked fuel cell that generates a DC output of 250 kW, the number of stacked layers of the unit cell 1 is approximately 500, and N·E ₀ is approximately 500V. Therefore, if the connecting wire 19a is connected to the + electrode of the central unit battery 1, the maximum potential difference applied to the insulating member will be approximately
This means that it is possible to suppress the generation of spark discharge in any of the above gases.

Therefore, according to this embodiment, the manifold 10
and the power generation section 2 or the seal plate 5, and the cooler 3
Since the potential difference applied between the is maintained stably. Furthermore, the structure including the thickness of the insulating member can be simplified, and in particular, the insulating material 17 between the cooler 3 and the cooler holder 4 can be made thinner, which has the effect of improving cooling efficiency.

In addition, the center stage unit battery 1 in the above embodiment
Detailed structural diagrams of the electrical connection between the manifold 10 and the manifold 10 are shown in FIGS. 6a and 6b, FIGS. 7 and 8. As shown in the perspective view of FIG. 6a, the unit battery 1 is formed by laminating an electrode 20, a matrix 21, and a separator 22.
Terminal 2 connecting the tangent line 19a to opposite corners of
3 is formed. The manifold 10 is designed to be installed as shown by the two-dot chain line in FIG. 6a. This manifold 10 has a sixth
As shown in the plan view of FIG. b, a terminal is formed to which the connecting wire 19a is connected. In addition, the seventh
Even if the manifolds 10 and the separators 22 are connected as shown in the figure, the effect is the same. Although not shown, the cooler 3 or the tightening fittings 8
Connections between a, 8b and the manifold 10 may be formed in the same manner.

8a to 8c show an embodiment in which terminals 23 are formed on separator 22. FIG. Figure a shows a structure in which the separator 22 and the terminal 23 are integrally formed, and figures b and c show a structure in which the terminal 23 or the connecting wire 19a is connected to the separator 22 by adhesive or molding. Also, this pull-out terminal 2
3 has the same effect whether it is attached to the separator 22 or the electrode 20 as described above.

〔Effect of the invention〕

As explained above, according to the present invention, since the thickness of the insulating member can be reduced, the insulating structure is simplified, the cooling efficiency is improved, the dielectric strength voltage is stably maintained, and the number of stacked layers is reduced. This has the effect of increasing the output voltage by increasing the output voltage.

[Brief explanation of drawings]

1A and 1B are front sectional views and plan sectional views of the conventional example, FIG. 2 is a schematic equivalent circuit diagram of the conventional example shown in FIG. 1, and FIG. 3 is a partial detailed view of the conventional example shown in FIG. 4a and b are a front sectional view and a plan sectional view of one embodiment of the present invention, FIG. 5 is a schematic equivalent circuit diagram of the embodiment shown in FIG. 4, and FIGS. 6a and b are respectively FIG. 7. Partial details of the illustrated embodiment, FIGS. 7 and 8 a to c are partial detailed views for explaining modified examples. DESCRIPTION OF SYMBOLS 1... Unit battery, 3... Cooler, 10... Manifold, 11... Sealing material, 17... Insulating material.

Claims (1)

[Claims] 1 Unit cells stacked in multiple stages, a reaction gas supply/discharge manifold integrally formed of a conductive material and attached to the reaction gas supply/discharge port of each unit battery via a first insulating member, and a reaction gas supply/discharge manifold made of a conductive material. A stacked fuel cell comprising: a cooler integrally formed and inserted between the unit cells as appropriate via a second insulating member; and one electrode of the stacked center stage unit cells; A fuel cell characterized in that the manifold and the cooler are electrically connected.