JP2776646B2 - Structure of vacuum insulation box - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a vacuum heat insulating box, and more particularly to a structure of a vacuum heat insulating box suitable for accommodating high-temperature items.

[0002]

2. Description of the Related Art As shown in FIG. 9, for example, a conventional vacuum insulation box is formed by forming an inner box 1 and an outer box 2 into a double-walled box having an opening 3 on one side. A vacuum heat insulating layer 4 is formed between 1 and the outer box 2. In addition, the vacuum insulation layer 4
Of the inner box 1 and the outer peripheral edge of the outer box 2 are connected to each other by a membrane 5 for sealing the inner wall. A vacuum insulation container is formed by covering the flange 7 provided on the open peripheral edge of the outer box 2 with the insulation cover 8. The vacuum heat insulating layer 4 is filled with a powder heat insulating material. The membrane 5 is made of a thin plate, and is configured to reduce heat radiation due to heat conduction and maintain heat insulation properties.

[0003]

However, when a high-temperature article is accommodated in the above-mentioned conventional vacuum insulated box, the inner box 1 rises in temperature and expands toward the membrane by a length Δl as shown in FIG. . Then, in the illustrated end structure, deformation concentrates on the membrane 5 and a large stress is generated in the illustrated a portion.

The cause will be described with reference to FIG. When the inner box 1 expands toward the membrane by Δl, the inner box 1 expands as shown in FIG.
As shown in FIG. 10, a compressive stress and a tensile stress due to bending are generated on the inner surface and the outer surface of the membrane at the portion a in FIG. Further, as the expansion of the inner case 1 and the membrane 5 in the circumferential direction is restrained by the outer case 2, a compressive stress is generated in the cross section of the portion a in FIG. 10 as shown in FIG. For this reason, as shown in FIG.
(a) The total stress of (b) is generated, and a large compressive stress is generated particularly on the surface of the membrane 5 on the vacuum layer side. As a result, when heating and cooling of the inner box 1 are repeated, this part a may be damaged by thermal stress, and there is a problem that the life, that is, the durability of the vacuum insulated box body is reduced.

[0005] Accordingly, an object of the present invention is to solve such a problem and to alleviate the stress acting on the membrane to improve the life of the vacuum heat insulating box.

[0006]

In order to achieve the above object, the present invention forms a double-structured box having an opening on one side by an inner box and an outer box. A vacuum heat insulating layer is formed on the inner side of the inner box and the outer side of the outer box by a membrane that seals the vacuum heat insulating layer. A curved portion is formed to increase the thermal resistance of the inner box in the direction of, and a heat insulating material and a deformation suppressing member for limiting the deformation of the curved portion to a certain range are provided inside the curved portion.

[0007]

In the vacuum heat insulating box having the above-described structure, the curved portion is formed in a portion of the inner box in the vicinity of the membrane, so that the heat transfer path in that portion becomes longer and the thermal resistance increases. Therefore, the temperature of the peripheral portion of the inner box on the opening side and the temperature of the membrane decrease, and the compressive stress (FIG. 11 (b)) due to the expansion of the inner box and the membrane in the circumferential direction decreases. Further, since the deformation suppressing member is provided inside the bending portion, the deformation of the bending portion is restricted, and the stress generated in the bending portion becomes equal to or less than the stress generated in the membrane. As a result, the life of the vacuum insulated box against thermal stress is improved. Furthermore, the heat insulating material inside the curved portion eliminates air gaps to prevent air convection, and increases the thermal resistance of the heat bridge portion to reduce the amount of heat radiation. Therefore, the heat insulating performance of the vacuum heat insulating box is improved.

[0008]

【Example】

(Embodiment 1) As shown in FIG. 1 and FIG. 2, a curved portion 19 for increasing thermal resistance in a direction from the inside of the inner box 1 toward the membrane is provided in a portion of the end wall 6 of the inner box 1 near the membrane. Are formed so as to protrude into the vacuum heat insulating layer 4. The inside of the curved portion 19 is filled with a heat insulating material 20 and, as shown in FIG.
Are inserted at appropriate intervals. In addition, a holding member such as a wire mesh is
By providing the heat insulating material 20 and the deformation suppressing member 21
Are supported so as not to escape from the curved portion 19. Insulation
20 is preferably rock wool, glass wool, ceramic wool, or the like. Further, the deformation suppressing member 21 may be a saddle-shaped frame as shown in FIG.
It is formed in a block shape as shown in FIG. As the material, a calcium silicate molded body having a pressure resistance and a certain degree of heat insulating property, a heat insulating caster, or the like is used.

When a high-temperature article is accommodated in the vacuum insulation box having the above-mentioned structure, the temperature of the inner box 11 rises. At this time, the bending portion 19
Will extend the heat transfer path of the end wall 6 and increase its thermal resistance. Therefore, even if the temperature of the inner box 1 rises,
The temperature of the peripheral portion of the end wall 6 on the opening side and the temperature of the membrane 5 are lower than when the curved portion 19 is not formed. For this reason,
The compressive stress generated at the edge A of the membrane 5 due to the circumferential expansion of the end wall 6 and the membrane 5 (FIG. 11)
(b)) decreases.

Further, since the deformation suppressing member 21 is inserted into the inside of the curved portion 19, the expansion of the inner box 1 toward the membrane due to the temperature rise causes the amount of deformation of the curved portion 19 as shown in FIG. It is absorbed by ΔL and the deformation amount ΔM of the membrane 5. Therefore, the deformation amount ΔM of the membrane 5 is smaller than the deformation amount when the curved portion 19 is not formed, that is, Δl in FIG. 10, and the bending stress generated at the edge portion A due to the expansion of the inner box 1 (FIG. 11A) ) Decreases. At the same time, if the allowable deformation amount ΔL in the bending portion 19 is appropriately set, the bending portion 19
Can be limited to be equal to or less than the stress generated in the membrane 5. In some cases, the deformation suppressing member 21 may be thickened to set the deformation amount ΔL to zero.

As a result, the thermal stress generated in the vacuum insulated box is reduced, and the life of the vacuum insulated box with respect to the repeatedly applied thermal stress is improved. Further, the heat insulating material 20 filled in the inside of the curved portion 19 eliminates a gap in the curved portion 19 to prevent convection of air, and also increases the thermal resistance of the heat bridge portion to reduce the amount of heat radiation. Therefore, the heat insulating performance of the vacuum heat insulating box can be improved.

[0012] Adiabatic boundary indicated by the shaded portion of FIG. 5, the results obtained by heat transfer calculation relation of one-dimensional temperature T _A of the length X and the edge A of the membrane 5 of the bending portion 19, FIG. 6 Is shown in the graph. However, in FIG.
Of length equal to the length L of the membrane 5, 300 ° C. the temperature T _B of the inner portion B of the end wall 6, the temperature T _C of the outer box side edge C of the membrane 5 was 0 ° C.. As can be seen from FIG. 6, if the length X of the curved portion 19 is equal to the length L of the membrane 5, the temperature T _A of the edge A in the case of not forming the curved portion 19 15
Significantly drops from 0 ° C to 100 ° C. Thereby, the edge A
Compressive stress (FIG. 11 (b)) is reduced to about 2/3. In order to make the length X of the bending portion 19 2 L or more, two or more bending portions 19 are formed to cope with this. (Embodiment 2) As shown in FIG. 7, two curved portions 19 in the first embodiment are formed on the end wall 6, and the length of the curved portion 19 is doubled. With such a structure, the compressive stress (FIG. 11 (b)) generated at the edge A of the membrane 5 can be greatly reduced, and the heat insulation performance can be improved. (Embodiment 3) As shown in FIG. 8, the membrane 5 in Embodiment 1 has a three-layer bellows structure to facilitate deformation. As a result, the thermal stress generated at the edge A (FIG. 11)
(c)) can be reduced.

[0013]

As described above, according to the present invention, a curved portion is formed in the vicinity of the membrane of the inner box to increase the thermal resistance in the direction from the inside of the inner box to the membrane.
Even when the temperature of the inner box rises due to the contents, the rise in the temperature of the connection between the membrane and the inner box is suppressed, and the generated stress can be reduced. Further, since the deformation suppressing member provided in the bending portion limits the deformation of the bending portion to a certain range and averages the stress generated in the bending portion and the membrane, the stress generated in the bending portion is limited to a certain value or less. Can be. As a result, the durability of the vacuum insulated box against thermal stress can be improved.

Further, the heat insulating material provided in the curved portion eliminates air gaps to prevent air convection, and increases the thermal resistance of the heat bridge portion to reduce the amount of heat radiation. Can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a vacuum insulated box according to one embodiment of the present invention.

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

FIG. 3 is a sectional view of a modification of the part shown in FIG.

FIG. 4 is a perspective view of a deformation suppressing member in FIG. 3;

5 is an explanatory diagram of an adiabatic boundary modeled for performing heat transfer calculation for the vacuum insulated box of FIG. 1;

FIG. 6 is a graph showing the relationship between the length of a curved portion and the temperature of a membrane obtained by a heat transfer calculation based on the model of FIG.

FIG. 7 is a sectional view of a main part of a vacuum heat insulating box according to another embodiment of the present invention.

FIG. 8 is a sectional view of a main part of a vacuum insulated box according to still another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing an example of a conventional vacuum heat insulating box.

10 is an enlarged sectional view showing an end structure of the conventional vacuum heat insulating box shown in FIG.

FIG. 11 is an explanatory diagram of stress generated in a membrane in a conventional vacuum heat insulating box.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner box 2 Outer box 3 Opening 4 Vacuum heat insulating layer 5 Membrane 19 Curved part 20 Heat insulating material 21 Deformation suppressing member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16L 59/00-59/22 F25D 23/06 F28F 9/00

Claims (1)

(57) [Claims] An inner box and an outer box form a double-structured box having an opening on one side, a vacuum heat insulating layer is formed between the inner box and the outer box, and the vacuum heat insulating layer is sealed. In a vacuum heat-insulating box in which the opening side edges of the inner box and the outer box are connected by a membrane, in a portion of the inner box near the membrane,
A curved portion for increasing the thermal resistance of the inner box in the direction from the inside to the membrane is formed, and a heat insulating material and a deformation suppressing member for limiting the deformation of the curved portion to a certain range are provided inside the curved portion. The structure of a vacuum insulated box characterized by the following.