JPS59144317A - electrical insulation fittings - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electrically insulating joint used for joining metal pipes when liquid helium is passed through the metal pipes provided in the superconducting wire to cool the superconducting wire.

Conventionally, methods for cooling superconducting wires include (1) immersing the wires in liquid helium, a coolant;

(2) A method of passing liquid helium (hereinafter abbreviated as LHe) through a pipe provided in a superconducting wire.

Two ways are known.

In method (2) above, an electrically insulating joint is installed in a part of the piping so that the current flowing through the superconducting wire does not flow into the refrigerator system that supplies LHe.

As electrically insulating joints, for example, those made of ceramic and stainless steel (SUS' 304) are known. An example of its structure is shown in FIG.

That is, the insulating joint A used to connect the nodding pipe 1.1 in the superconducting wire is made of ceramic 2 and stainless steel 3, both of which are joined by welding.

However, since the LHe internal pressure of 10 atmospheres or more, which is the operating pressure of the refrigerator, is applied to the welded part of the lever, it is necessary to weld with sufficient airtightness to prevent helium gas from leaking from the welded part to the external vacuum. . -However, the welded joints between ceramic and stainless steel are 1000%
Thermal distortion remains when the temperature is returned to room temperature after being heated above ℃, and the difference in thermal shrinkage when cooled to the LHe temperature may cause welded joints to leak or cause separation in the ceramic. The disadvantage is that it is very difficult to weld together stainless steel and stainless steel.

In view of the above points, the inventor of the present invention has studied the improvement of electrical insulating joints, and has found that they are easy to join with electrical insulators, and there is no leakage to the outside even through LHe, that is, airtightness is achieved. An electrically insulating joint with an excellent structure has been discovered.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an electrically insulating joint according to the present invention will be explained below based on drawings showing one embodiment thereof.

That is, the present invention provides an electrical insulating joint in which the electrical insulator 11 is made of glass fiber reinforced epoxy resin (GFRP), and the metal pipe 12 is made of, for example, Cu, which has smaller thermal shrinkage than GFRP at the LHe temperature. It is.

Both GFRP and Go are first bonded at room temperature with a suitable adhesive (for example, a commercially available epoxy resin adhesive that is strong and does not crack at low temperatures).

In this case, the direction of the glass cloth C in GFRP is as shown in Figure 3, so that it can easily withstand the internal stress 6 from the pith when it is cooled in Ll-1e. It is.

The electrically insulating joint of the present invention has the above-described structure, and since the insulator and metal can be joined at room temperature, there is little heat generation during joining, and when LHe is passed through, the insulator and metal are in the direction of tightening each other. Since the material is thermally shrunk, there is no risk of helium gas leaking, and the effect is that no minute distortion occurs.

Furthermore, because it is a room-temperature bonding process, it requires less time and effort compared to conventional welding and therefore has the advantage of lower manufacturing costs.

This electrical insulation joint can be widely used as an insulation joint for coils using forced cooling superconducting conductors.

Next, the airtightness of the electrically insulating joint of the present invention was examined using an experimental apparatus as shown in FIG. 4, and very good results were obtained.

That is, the superconducting coil 13 is connected to the refrigerator 1 in the vacuum vessel 14.
Attach the LHe inlet pipe 16 and the discharge pipe 16' of 5 or d. The electrical insulation joint 11 according to the present invention was installed at a location in the vacuum vessel 14 of '16'.

Then, 4", 2K L He was flowed from the refrigerator 15 through the LHe introduction pipe 16 at 10 atmospheres into the pipe in the superconducting coil 13 in the vacuum vessel 14, and returned to the refrigerator 15 again at about 6 degrees. When the leakage of helium gas from the electrically insulating joint 17.17 of the present invention was detected by a helium gas leak detector 18 connected to the vacuum vessel 14 and attached outside the vessel, it was confirmed that the leakage occurred vertically, and the electrically insulating joint of the present invention was confirmed to have excellent airtightness.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the structure of a conventional electrical insulation joint;
The figure is a cross-sectional view showing the structure of the electrically insulating joint of the present invention.
The figure is a sectional view showing the laminated state of the glass fiber reinforced epoxy resin insulator and the metal vibrator in the electrically insulating joint of the present invention, and FIG. 4 is a schematic diagram of a measuring device for measuring the performance of the electrically insulating joint. . 11... Electric insulator 12... Metal vibrator 1
3... Superconducting coil 17... Electrical insulation joint, 1
8... Leak detector patent applicant Sumitomo Electric Industries Co., Ltd. Agent Patent attorney Kazu 1) Showai 1
Figure 2 Figure 4 Figure 7

Claims (1)

[Claims] In a method of forcibly cooling a superconducting conductor by passing liquid helium through a passage provided in the superconducting conductor, a metal pipe is used as an electrically insulating joint between the superconducting conductor and a refrigerator system used for cooling, using glass fiber reinforced plastic as an insulating material. An electrically insulating joint characterized by being wrapped around the outside of the pipe and bonded at room temperature.