JPH07226192A - Double-framed wall housing - Google Patents

Abstract

PURPOSE: To shorten time for evacution and reduce heat conduction from a thermal insulation material to wall surfaces, by providing, between an inner wall/an outer wall and a thermal insulation material for cavity filling, an intermediate layer composed of a material having a density lower than that material. CONSTITUTION: This installation is suitably used for a high-voltage electrochemical storage battery whose operation temperature is about 300 deg.C. A panel-shaped thermal insulation material 3 composed of ceramics, glass fiber, or a compression-molded granular-type material or the like is provided between a high-temperature inner wall 2 composed of a special steel or the like and an outer wall 1. Further, additional intermediate materials 4, 5 having a density lower than the material 3 are provided in the form of layer between the material 3 and the inner wall 2 and/or the outer wall 1. Accordingly, the intermediate materials 4, 5 has a good thermal insulation property because they are more porous than the material 3 and a diffusion of residual gas is improved. Furthermore, the intermediate materials 4, 5 can be formed of a material of the same quality as the material 3 if only a lower density is available and their shape can be of a mat or corrugation.

Description

Detailed Description of the Invention

The present invention relates to double wall housings.

According to the invention, an inner wall, an outer wall spaced from the inner wall such that a cavity in vacuum is provided between the walls, a heat insulating material at least partially filling the cavity, the inner wall or the outer wall or its A double-walled housing is provided, which comprises a heat-resisting intermediate material with a density lower than that of the heat insulating material, configured as a layer between both and the heat insulating material.

The double-walled housing of the present invention is particularly suitable for high voltage electrochemical storage batteries.

High voltage electrochemical storage batteries, such as Na / NiCl ₂ based batteries, operate at relatively high temperatures, eg, about 300 ° C. To maintain this operating temperature of the accumulator, the battery must have a housing that thermally insulates its cells, and thus itself from the environment.
Vacuum insulation as described in US Pat. No. 5,137,169 has proven to be particularly effective.

According to US Pat. No. 5,137,169, the accumulator housing comprises a thin special steel sheet double-walled casing that is vacuum tightly welded and the space between the walls is evacuated. A heat insulating material in the form of a pre-compression molded panel is located between the two walls.
These panels may be made of ceramic fiber, glass fiber, or commercially available powder material.

The space between the two walls where the heat insulating material is located can be evacuated by means of short tubes attached to the inner or outer wall of the casing. The thermal insulation of the accumulator housing is significantly improved by the vacuum created between the two walls, thus reducing heat loss during operation of the battery.

However, at present, in the manufacture of such battery housings, the evacuation of the battery housing can be time consuming because the insulating material between the two walls provides a significant diffusion resistance to residual gas. I know it. Such long evacuation times, which can take up to 2 days depending on the size of the battery housing, add to the cost of the manufacturing process for the battery housing. Therefore, it is an object of the present invention to provide a configuration that allows the time required for this evacuation to be reduced.

US Pat. No. 5,137,169 also describes a panel having milled grooves that facilitate the suction of residual gas. However, such grooves are only locally effective and most areas of the insulating panel are unaffected by this measure. In such areas, the panel-shaped insulating material completely bonds to the two walls and continues to conduct heat from the insulating material to the casing material. Therefore, another object of the invention is at the same time to reduce this heat transfer from the insulating panel to the casing material.

These objects are met by the double-walled housing according to the invention.

The intermediate layer of relatively low density material has a much higher porosity than the insulating material itself, thus allowing improved diffusion of residual gases and, as a result, reduced vacuum time. . The intermediate material may be the same as the insulating material. However, it is also possible to use different materials, for example glass fiber mats. This relatively low density layer also reduces the transfer of heat from the actual insulating material to the outer wall. At this point, the temperature within the insulating material has already dropped to the room temperature range of the outer wall, so that there is little radiative heat transfer. As a result, heat loss is also reduced.

The invention will be described in detail below with reference to exemplary embodiments shown in the drawings.

[0012]

The drawing shows a sectional view of a part of a double-walled housing of a high-voltage electrochemical storage battery according to the invention, in which an operating temperature of about 300 ° C. is predominant. Therefore, the inner wall 2 of the housing is also substantially at this operating temperature. The outer wall 1 of the housing is enclosed at ambient temperature. Provided between the inner wall 2 and the outer wall 1 is a heat insulating material 3, preferably in the form of a panel. The wall is made of special steel, for example. Said heat insulating material comprises, for example, ceramic fibres, glass fibres, materials of the granular type in the compression molded form, for example.

According to the invention, the additional intermediate material 4, 5 which also has a thermal resistance at the operating temperature of the battery and has a lower density than the heat insulating material 3 is the heat insulating material 3 and the inner wall 2 or the outer wall 1 or its It is provided as a layer between both. The intermediate materials 4, 5 may be matte or corrugated, for example. The intermediate material may be the same material as the heat insulating material 3, but the porosity of the intermediate material is higher than that of the heat insulating material because the density of the intermediate material is lower than the density of the heat insulating material. The intermediate material also has good thermal insulation properties.

These intermediate layers 4, 5 improve the thermal insulation properties of the double-walled vacuum exhaust housing, shorten the vacuum exhaust time, and make the housing easier to manufacture. Since the heat insulating material 3 and the intermediate materials 4 and 5 are formed of a molding material, of course, the atmospheric pressure acts on the outside of the inner wall 2 and the outer wall 1, so that the two walls 1 and 2 are mutually supported. Additional effect can be obtained. This double-walled housing can be considered a type of Dewar.

[Brief description of drawings]

1 shows a sectional view of a part of a double-walled housing of a high-voltage electrochemical storage battery according to the invention.

[Explanation of symbols]

 1 Outer wall 2 Inner wall 3 Thermal insulation material 4 Intermediate material 5 Intermediate material

Claims (6)

[Claims] 1. An inner wall, an outer wall spaced from the inner wall such that a vacuum cavity is provided between the walls, a thermally insulating material that at least partially fills the cavity, and an inner wall and / or an outer wall. A double-walled housing comprising a heat-resisting intermediate material having a density lower than that of the heat-insulating material, configured as a layer between the material and the heat-insulating material. 2. The double-walled housing according to claim 1, wherein the inner wall, the outer wall, or both are made of metal. 3. The double-walled housing of claim 2, wherein the intermediate material has a fiber structure. 4. The double-walled housing of claim 3, wherein the intermediate material is a fiber mat. 5. The double-walled housing of claim 4, wherein the intermediate material is a glass fiber mat. 6. The double-walled housing according to claim 1, wherein the intermediate material is corrugated.