JPH04266696A - Structure for eliminating thermal extention/contraction of vacuum thermal insulation body - Google Patents

Abstract

PURPOSE:To reduce thermal stress generated on a sealing member of a vacuum thermal insulation body or in the vicinity thereof by utilizing an inexpensive structure easy to manufacture. CONSTITUTION:An end face of a vacuum thermal insulation body 15 formed between inner and outer boxes. 11, 12 is sealed by means of a sealing member 16. The sealing member 16 is composed of a bellows member which can extend/ contract in a thermal extention/contraction direction of the inner box 11. In respect to plates 17 to 19 composing the bellows member, the plate near the inner box 11 gets gradually thicker than the plate on the side of the outer box 12. Stress applied to the plates 17 to 19 is equalized, and thereby generation of excessive stress is prevented, and durability of the vacuum thermal insulation body is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal expansion/contraction absorbing structure for a vacuum heat insulator that keeps objects stored in an interior chamber at a high or low temperature.

0002

[Prior Art] Conventionally, as this type of vacuum insulator,
As shown in FIG. 5, a bottomed box including an inner wall 1 and an outer wall 2 is known. This box body is constructed so that its opening 3 is closed with a lid body 4, and a vacuum insulation part 5 is formed between the inner wall 1 and the outer wall 2, and the end surface on the side of the opening 3 is sealed with a sealing member. It is sealed by 6. Generally, the sealing member 6 is attached to the inner wall 1
It is necessary to create a structure that can absorb the thermal expansion and contraction of vacuum insulation and reduce the thermal stress generated in the vacuum insulation. By the way, as shown in detail in FIG. 6, the illustrated conventional sealing member 6 has a groove-shaped cross-sectional shape, and both side edges of the sealing member 6 are welded to the inner wall 1 and the outer wall 2. However, since this alone cannot absorb the thermal expansion and contraction of the inner wall 1, grooves 7 are formed in the wall surface of the inner wall 1 to absorb this thermal expansion and contraction.

Furthermore, as another example of the sealing member 6, FIG.
and as shown in FIG. In the sealing member 6 shown in FIG. 7, the sealing member 6 has a C-shaped cross-sectional shape, and both ends of the sealing member 6 are welded to the inner wall 1 and the outer wall 2. Therefore, when the inner wall 1 undergoes thermal expansion and contraction, it deforms and absorbs this thermal expansion and contraction. Moreover, in the one shown in FIG. 8, the sealing member 6 is formed in a bellows shape that can be expanded and contracted in the direction of thermal expansion and contraction of the inner wall 1. Here, the three plates 8, 9, and 10 forming the bellows all have the same plate thickness.

0004

[Problems to be Solved by the Invention] However, among the above-mentioned conventional heat expansion/contraction absorption structures, the one shown in FIG. 6 reduces the stress generated near the sealing member 6, but depending on the conditions, Excessive stress may occur. Also, Figure 7
In the case shown in , excessive stress may be generated in the welded portion of the sealing member 6. Furthermore, since the welded portion must be processed with high precision, there is a problem in that it is disadvantageous in terms of manufacturing. Furthermore, what is shown in FIG.
There is a drawback that the stress generated at parts 9 and 10 differs for each plate material, and there are parts with short fatigue life.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve these problems and to reduce the thermal stress generated in the sealing member and its vicinity by using a structure that is easy to manufacture and inexpensive. .

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention has an inner wall and an outer wall, and seals the end face of a vacuum insulation section formed between the inner wall and the outer wall with a sealing member. In the vacuum heat insulating body, the sealing member is made of a bellows material that can expand and contract in the direction of thermal expansion and contraction of the inner wall, and the thickness of the plate material of the bellows material is such that the side of the plate material connected to the inner wall is thicker and the plate material is connected to the outer wall. The thinner the plate material side is, the thinner it is.

[0007]

[Operation] In the heat expansion/contraction absorption structure having the above configuration, the sealing member is made of a bellows material that can expand and contract in the direction of thermal expansion and contraction of the inner wall, so the sealing member smoothly absorbs the thermal expansion and contraction of the inner wall.
Reduces thermal stress generated in vacuum insulation. In addition, the thickness of the plate material constituting the bellows material is made thicker on the side of the plate material connected to the inner wall, that is, the side where a large stress is likely to be generated, and thinner as the plate material side connected to the outer wall, that is, the side where the stress is expected to be smaller. This setting equalizes the stress generated in the bellows material. Therefore, the durability of the vacuum insulation body is increased.

[0008]

[Embodiment] The embodiment shown in FIGS. 1 to 3 is a vacuum heat insulating body.
A vacuum insulated box body that keeps stored items at a high temperature is illustrated. As shown in FIGS. 1 and 2, this vacuum insulated box is a bottomed box including an inner box 11 as an inner wall and an outer box 12 as an outer wall. The opening 13 is closed with a lid 14. A vacuum heat insulating section 15 is formed between the inner box 11 and the outer box 12, and the end surface of the vacuum heat insulating section 15 on the opening 13 side is sealed with a sealing member 16.

Next, the thermal expansion/contraction absorption structure of this vacuum insulated box will be explained. As shown in FIG. 3, the sealing member 16 is made of a bellows member that can expand and contract in the direction of thermal expansion and contraction of the inner box 11, and among the three plate members 17, 18, and 19 forming the bellows,
The thickness of the first layer of plate material 17 welded to the inner box 11 closest to the open end is set to be the thickest. And the second layer plate material 18
The thickness of the third layer plate 19 welded to the outer case 12, which is the innermost layer, is set to be the thinnest.

According to the thermal expansion/contraction absorption structure having the above configuration, when the inner box 11 is expanded due to high temperature, the sealing member 16 having the bellows structure also expands to smoothly absorb the expansion of the inner box 11, and the vacuum insulation box Reduces thermal stress generated in the body. At this time, the amount of deformation, that is, the stress that is going to occur in the three plate materials 17, 18, and 19, is the largest in the plate 17, the intermediate in the plate 18, and the smallest in the plate 19. However, if the plate material 17 is the thickest,
Since the plate material 18 is set to have an intermediate thickness and the plate material 19 is set to be the thinnest, the stress generated in each of the plate materials 17, 18, and 19 is uniform and has a small value.

[0011] As described above, in the vacuum insulated box, the generated thermal stress is small and the stress in the thermal expansion/contraction absorbing structure is made uniform, so that the fatigue life against repeated thermal loads is extended. Moreover, such a heat-stretchable absorbing structure has a simple structure, is easy to manufacture, and is inexpensive.

[0012] Table 1 shows the results of a prototype test conducted by the present inventors on the heat-stretchable absorbent structure of this example.

[0013]

[Table 1]

[0014] However, the stress intensities in the table are the stress intensities determined by FEM analysis in accordance with ASME (=maximum principal stress -
(minimum principal stress), and its value shows the ratio, taking the value of conventional product A as 1. In addition, the vacuum insulation box has internal dimensions of 1400 mm width x 1200 mm height x 2300 mm length.
The thickness of the vacuum insulation part 15 is 60 mm, and the internal temperature is 330 mm.
℃.

As can be seen from the above table, the present invention has superior stress strength and life compared to the conventional one. In the above embodiment, a case has been described in which the stored items are kept at a high temperature. As another example, a thermal expansion/contraction absorption structure for keeping the stored items at a low temperature is shown in FIG. In this case, since the inner box 11 contracts due to low temperature, the plate material 17 to be welded to the inner box 11 is set as the innermost layer and its thickness is set to be the thickest, and the thickness of the intermediate layer plate material 18 is set to the thickness of both plate materials 17 and 17. ,19
The thickness is set to be intermediate, and the plate material 19 to be welded to the outer box 12 is set to be the layer closest to the open end, and its thickness is set to be the thinnest. As a result, the same effects as in the embodiments shown in FIGS. 1 to 3 can be achieved.

[0016]

As described above, according to the present invention, the sealing member is made of a bellows material that can expand and contract in the direction of thermal expansion and contraction of the inner wall, so that the sealing member smoothly absorbs the thermal expansion and contraction of the inner box. Therefore, the thermal stress generated in the vacuum insulated box can be reduced. In addition, the thickness of the plates constituting the bellows material is set to be thicker on the side of the plate connected to the inner wall and thinner on the side of the plate connected to the outer wall, so that the stress generated in each plate can be made uniform. Furthermore, the structure can be simple and manufacturing can be facilitated. Therefore, not only can the durability of the vacuum insulation body against repeated thermal loads be increased, but also it can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a vacuum insulation box using a thermal expansion/contraction absorption structure according to an embodiment of the present invention.

FIG. 2 is a right side view in FIG. 1.

FIG. 3 is an enlarged cross-sectional view of the thermal expansion/contraction absorption structure shown in FIG. 1;

FIG. 4 is an enlarged cross-sectional view of a heat-stretchable absorbing structure according to another embodiment of the present invention.

FIG. 5 is a sectional view of a vacuum insulation box using an example of a conventional thermal expansion/contraction absorption structure.

FIG. 6 is an enlarged cross-sectional view of the thermal expansion/contraction absorption structure shown in FIG. 5;

FIG. 7 is an enlarged sectional view showing another example of a conventional thermal expansion/contraction absorption structure.

FIG. 8 is an enlarged cross-sectional view showing still another example of a conventional thermal expansion/contraction absorption structure.

[Explanation of symbols]

11 Inner box (inner wall) 12
Outer box (outer wall) 15
Vacuum insulation part 16 Sealing member 17, 18, 19 Plate material

Claims (1)

[Claims] 1. A vacuum insulation body having an inner wall and an outer wall, and in which an end face of a vacuum insulation portion formed between the inner wall and the outer wall is sealed with a sealing member, wherein the sealing member is used to control thermal expansion and contraction of the inner wall. A vacuum insulating body comprising a bellows member that can be expanded and contracted in the direction, and the thickness of the plate of the bellows member is set to be thicker on the side of the plate connected to the inner wall and thinner as the side of the plate connected to the outer wall is set. Heat-stretch absorption structure.