JPS5855730B2 - Terminals of cryogenic cables, etc. - Google Patents

Description

Detailed Description of the Invention The present invention provides power supply for cryogenic equipment such as cryogenic cables such as cryogenic resistance cables and superconducting cables or superconducting magnets located across both cryogenic temperature regions and normal temperature regions. This relates to the terminal portion of a conductor (hereinafter referred to as a cryogenic cable, etc.).

At the end of cryogenic cables, etc., there is a large temperature difference between the cryogenic temperature and room temperature, which causes many technical problems.

One of the problems is the shrinkage of the bushing cone.
As shown in Fig. 1a, the cylindrical part 4' of the flange fitting 3' is embedded in a rubber or plastic bushing cone 2 provided around the conductor 1, and the flange part 5' provided around the cylindrical part 4' is used for polarization. At the end of a cryogenic cable or the like in which a low-temperature region 6 and a normal-temperature region 7 are airtightly divided, the bushing cone 2' should be able to slide freely on the conductor 1'. It contracts as shown in Figure 1.

That is, since the coefficient of thermal expansion of the bushing cone 2 is thicker than that of the flange fitting 3', the bushing cone 2' contracts greatly, and the bushing cone 2 on the cryogenic region 6 side in the directions of arrows A and B at both ends of the cylindrical portion 4' It contracts in the direction of arrow C.

However, both ends 12' and 14' of the cylindrical portion 4, that is, the fixing portion between the bushing cone 2' and the flange fitting 3' are not connected to the bushing through the flange fitting 3' not only in the extremely low temperature region side but also in the normal temperature region side. Since the cone 2 is cooled below its embrittlement temperature (generally referred to as the temperature at which flexibility is not lost and elongation is reduced), the bushing cone 2' near the fixing part is When shrinkage stress acts, it becomes impossible to absorb it, and as a result, cracks 1
3.15 is generated and peeled off easily.

When these defects occur, there are problems in that airtightness between the cryogenic temperature region and the room temperature region cannot be maintained, and electrical characteristics deteriorate.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to prevent cracks and conflicts between the bushing cone and the flange fitting even if the bushing cone shrinks.
The purpose is to provide a terminal part for cryogenic cables, etc. that does not cause separation, etc., and the content is that the cylindrical part of the flange fitting is attached to the rubber or plastic bushing cone surrounding the conductor. At the end of a cryogenic cable, etc., which airtightly separates a cryogenic region and a normal temperature region by a flange provided at The cylindrical part in the normal temperature range is connected and fixed to the bushing cone at its end, and the end part, which is cooled in the cryogenic region, has a temperature higher than the embrittlement temperature of the bushing cone material. The feature is that the length of the cylindrical portion is adjusted so that

The present invention will be explained in detail with reference to illustrated embodiments.

FIG. 2 is an example showing a schematic configuration of the terminal part of the cryogenic cable etc. according to the present invention, in which 1 is a conductor, 2 is a bushing cone made of rubber or plastic, and 3 is a cryogenic region 6 and a normal temperature region 7. This is a flange metal fitting that is airtightly divided, and the flange metal fitting 3 has a structure as described below.

In addition, 8 is a refrigerant, 9 is a cooling container, 10 is an insulated pipe provided as necessary, and 11 is a heat insulating material.

FIG. 3 shows the state of connection between the bushing cone 2 and the flange metal fitting 3. The cylindrical part 4 of the flange metal fitting 3 is fitted into the bushing cone 2, and only the end 12 of the cylindrical part 4 on the normal temperature range γ side is connected to the bushing cone 2. A cryogenic region 6 and a normal temperature region 7 are airtightly separated by a flange 5 embedded in the cylindrical portion 4 and provided around the cylindrical portion 4 .

16 is an adhesive, and the end portion 12 is shown in FIGS. 4 a to d, which will be described later.
A hole or step is provided as shown in FIG.
Appropriately determine the distance to reach .

The distance is such that the end portion 12 of the cylindrical portion 4 in the normal temperature region 7, which is cooled by the cryogenic region 6, is at the embrittlement temperature of the bushing cone 2 (generally -100 to -50, although it varies depending on the material).
(°C) or more.

For example, according to experiments, the outer diameter is 48.4 mm and the thickness is 2.8 mm.
If one end of a mm stainless steel tube is immersed in liquid nitrogen at -196°C and the other end is left at room temperature, the temperature will drop approximately 20°C from the liquid level.
It has been confirmed that the temperature almost reaches equilibrium with room temperature at the position IIL, and although it varies depending on the shape and material of the cylindrical part 4,
The distance is about the same value.

It goes without saying that the other parts of the cylindrical part 4 in FIG. 3, except for the end 12, are not embedded and fixed in the bushing cone 2, but are made to be able to slide relative to the bushing 2. .

Next, a specific example of the flange fitting used in the present invention will be explained.

The embodiment shown in FIGS. 4a and 4d is a flange fitting 3 in which a hole or a step is provided at the end 12 of the cylindrical portion 4 at a distance from the collar 5, as described above, and a is the end. A large number of through holes 17 are provided in the portion 12, b is provided with grooves 18 on the outer periphery of the end portion 12, C is provided with a convex strip 19 on the inner periphery of the end portion 12, and d is provided with a protrusion 19 on the inner periphery of the end portion 12.
By providing the protrusions 20 on the outer periphery, the connection with the bushing cone 2 is strengthened.

Further, the embodiment shown in FIGS. 5a and 5b is for the case where the above-mentioned distance cannot be kept sufficiently, and the flange part 5 and the end part 12
A fin-like heat absorbing fin 21 is provided in the cylindrical portion 4 between the two.

In b, a shield ring 2 is further provided around the outer periphery of the fin 21 in order to avoid electrical effects such as discharge of the fin 21.
2 are provided.

In the above embodiment, the end portion 14 of the cylindrical portion 4 on the cryogenic region 6 side was placed along the outer periphery of the bushing cone 2, but in the present invention, It may be configured as shown.

That is, in the embodiment shown in FIG. 6, the end portion 14 is buried in the bushing cone 2, and the material between the end portion 14 and the bushing cone 2 is made of natural or synthetic fiber or synthetic resin such as Teflon, which does not lose its flexibility even at low temperatures. The bushing cone 2 is filled with a cushioning material 23 to prevent stress from acting between the bushing cone 2 and the end 14 even if the bushing cone 2 contracts.

Further, in the embodiment shown in FIG.
The end portion 14 is embedded in the bushing cone 2 with an adhesive 16, and a pleat 24 is formed in the cylindrical portion 4 between the end portion 14 and the flange portion 5, so that the bushing cone 2 contracts and the gap between the cylindrical portion 4 and It is designed to be able to absorb the stress that occurs.

Furthermore, the embodiment shown in FIG. 8 is used when the end portion 14 is buried in the bushing cone 2 as shown in FIGS. In order to further alleviate the stress, a comb-shaped shrinkable absorbing piece 25 is provided at the end portion 14.

Since the present invention has the above-described structure, even if the bushing cone 2 contracts as shown in FIG. 1, no cracks will occur in the bushing cone 2.

That is, in the normal temperature range, the length of the cylindrical part 4 from the flange part 5 to the end part 12 is sufficiently long, or the length of the cylindrical part 4 is made substantially longer by the fins, so that the temperature of the end part 12 connected to the bushing cone 2 is lowered by the bushing cone 2. Since the temperature is set above the embrittlement temperature without losing flexibility, there is no risk of cracking.

Further, since the end portion or step portion is provided, even if the bushing cone 2 contracts, no peeling occurs and airtightness is sufficiently maintained at this portion.

Furthermore, in the extremely low temperature region, since the end portion 14 of the cylindrical portion 4 is made freely contractible by the pleats even in the case of a free end or a fixed portion, cracks do not occur in the bushing cone 2 as well.

As explained above, when the terminal part of the cryogenic cable etc. according to the present invention connects and fixes the flange fitting to the bushing cone, even if the bushing cone has heat shrinkage,
Taking advantage of this effect, we created a connection structure that does not cause cracks, peeling, etc., so even materials with large heat shrinkage can be used satisfactorily as bushing cones, resulting in remarkable technological and economical effects. have

[Brief explanation of the drawing]

FIG. 1a is a partially cutaway cross-sectional view of a bushing cone used in a conventional cryogenic terminal section, FIG. 1 is an explanatory diagram showing a contracted state of the bushing cone shown in FIG. A schematic configuration diagram showing an example of the terminal part of such a cryogenic cable, etc., FIG. 3 is a partially cutaway front view of the bushing cone and flange fitting in FIG. 2, FIG. 4 a = d, and FIGS. 5 a and b are A partially cutaway front view showing an embodiment of the flange metal fitting used in the present invention, FIGS. 6 to 8 show the other side of the terminal part of the present invention, and FIGS. 6 and 7 show the bushing cone and the flange metal fitting. FIG. 8 is a partially cutaway front view of the flange fitting. 1 and 1' are conductors, 2 and 2' are bushing cones, and 3
．． 3' is a flange fitting, 4, 4' are cylindrical parts, 5, 5' are flange parts, 6 is a cryogenic region, 7 is a normal temperature region, 8 is a refrigerant, 12
, 12' is an end, 13 is a crack, 14, 14' is a narrow limit 15 is a crack, 17 is a through hole, 18 is a groove, 19.20 is a protrusion, 21 is a fin, 22 is a shield ring, 23 is a A cushioning material, 24 is a pleat, and 25 is a shrinkable absorbent piece.

Claims (1)

[Scope of Claims] 1. The cylindrical part of the flange fitting is attached to a rubber or plastic bushing cone surrounding the conductor, so that a cryogenic region and a normal temperature region are airtightly separated by a flange provided around the cylindrical part. At the end of the low-temperature cable, etc., the cylindrical part in the cryogenic region of the flange fitting is made to be slidable relative to the bushing cone or contractible by the folds provided in the cylindrical part, and the cylindrical part in the normal temperature region is attached to the end thereof. A cryogenic cable, characterized in that the length of the cylindrical part, etc. is adjusted so that the end part, which is connected and fixed to the bushing cone and cooled by the cryogenic region, has a temperature equal to or higher than the embrittlement temperature of the bushing cone material. Terminal section such as. 2. The terminal of a cryogenic cable or the like according to claim 1, wherein a heat absorbing fin is provided between the end of the cylindrical part in the normal temperature region of the flange fitting and the collar part to adjust the temperature of the end part. Department.