JPS6115381A - Superconductive switch - Google Patents

Abstract

PURPOSE:To reduce heater power kept at the switch-off state by a method wherein the winding part wound with a superconductive gate wire and a heater wire that heats the gate wire and a coolant path that cools this winding part by thermal conduction are provided to a superconductive switch. CONSTITUTION:In switching ON, a valve 14 is opend and the conduction of a heater 22 is stopped. This enables the winding part 23 to be cooled by thermal conduction with liquid helium passing through the coolant path 13; accordingly, the superconductive gate wire 21 comes into a state of superconduction. In switching OFF, the valve 24 is closed and the heater 22 is conducted. This enables the winding part 23 to be heated by the heater 22; accordingly, the superconductive gate wire 21 comes into a state of normal conduction. Here, when the valve 14 is closed, the coolant path 13 becomes filled with helium gas, and the winding part 23 gets the temperature readily increased by the heater 22. Thereby, switching off is enabled with a small heater power.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a superconducting switch for using a superconducting magnet used in a magnetically levitated train or the like in a persistent current state.

[Technical background of the invention and its problems]

Conventionally, superconducting switches have been used with the switch body immersed in liquid helium, as in the case of a superconducting magnet for a magnetically levitated train shown in FIG. Here, in the figure, 41 is the winding part of the superconducting magnet i to the main body, 42 is 2IaI (liquid helium container) containing liquid helium, and 45 is the superconducting switch main body. In addition, 48 is the switch body 4
5, and is connected to a liquid helium container 42.

However, this type of superconducting magnet 1 has the following problems. That is, since the superconducting switch body 45 is immersed in liquid thulium, a large amount of heater power is required to keep the switch in the OFF state. In addition, as shown in FIG. 4, if the liquid helium space is connected to the magnet 1 in a container independent from the winding part 41, the conducting wire 46 connecting the superconducting wire for the magnet and the superconducting switch gate wire must be vacuum-tight and electrically insulated. Seal portion 47 that also serves as
However, the reliability of this seal portion 47 was insufficient.

[Object of the Invention] An object of the present invention is to provide a superconducting switch that requires less heater power to maintain the switch in the OFF state and does not require an insulating airtight seal on the conductor wire connected to the superconducting wire for a superconducting magnet. .

[Summary of the invention]

The gist of the present invention is to cool the superconducting switch windings by thermal conduction.

That is, the present invention is a superconducting switch comprising a superconducting gate wire, a winding portion around which a heater wire for heating the gate wire is wound, and a refrigerant passage cooling the winding portion by thermal conduction. The switch is turned on by cooling by the heat conduction, and the switch is turned OFF by heating by the heater.

[Effects of the Invention] According to the present invention, the switch body is not directly cooled with liquid helium, but is cooled by heat conduction from the refrigerant passage, so the heater power required to keep the switch in the OFF state is reduced. It can be reduced. Furthermore, since an insulating airtight seal used at extremely low temperatures is not required, evaporation of liquid helium, which is a refrigerant, can be reduced and reliability can be improved.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a sectional view showing a schematic structure of a superconducting magnet according to an embodiment of the present invention. The first part in the figure is a magnet winding part in which a superconducting wire for a magnet is wound. The first winding part is arranged around a liquid helium container 12 and is cooled by the liquid helium in the container. A refrigerant passage 13 is connected to the liquid helium container 12, and this passage 1
Liquid helium is also passed through the interior of the tank. Further, a gate valve 14 is provided in a part of the refrigerant passage 13,
This valve 14 controls the flow of liquid helium within the refrigerant passage 13 .

On the other hand, a superconducting switch main body 15 is attached to the outer periphery of the refrigerant passage 13. This switch body 15 has a superconducting gate wire 2 on the outer periphery of the refrigerant passage 13 as shown in FIG.
1 and heater wire 22 are wound around each other. Then, the superconducting gate wire 21 is cooled by thermal conduction by liquid helium flowing through the coolant passage 13, and the heater wire 21 is cooled by heat conduction.
It is heated by 2. In addition, 16 in the figure
23 is a conductive wire connecting the first winding portion and the superconducting gate wire 21, and 23 is the superconducting gate wire 21 and the heater wire 22.
The figure shows the winding portion of the winding.

In such a configuration, when the switch is turned on, the valve 14 is opened and the heater 22 is de-energized. As a result, the winding portion 23 is cooled by thermal conduction by the liquid helium flowing through the coolant passage 13, and the superconducting gate line 21 enters a superconducting state. On the other hand, the switch OFF'F
When doing so, the valve 14 is closed and the heater 22 is energized. As a result, the winding portion 23 is heated by the heater 22, and the superconducting gate line 21 enters a normal conductive state. Here, when the valve 14 is closed, the refrigerant passage 13 is filled with helium gas, and the temperature of the winding portion 23 is easily raised by the heater 22. Therefore, it is possible to turn off the switch with less heater power. In addition, in the case of this configuration, the superconducting switch main body 15 is not immersed in liquid helium, but is placed on the outer periphery of the refrigerant passage 13 through which liquid helium flows. becomes unnecessary.

As described above, according to this embodiment, the winding portion 23 is not directly cooled with liquid helium, but is cooled by heat conduction of the piping forming the refrigerant passage 13, so that the valve 14 is not cooled directly with liquid helium.
By closing the winding portion 23, the temperature of the winding portion 23 can be easily raised. Therefore, the heater power needed to turn off the switch can be reduced. Further, since an insulating airtight seal used at extremely low temperatures is not required, there are advantages such as reducing evaporation of liquid helium, which is a refrigerant, and improving reliability.

FIG. 3 is a cross-sectional view showing the main structure of another embodiment. This embodiment differs from the previously described embodiments in that a thermal insulation layer 23 is provided between the refrigerant passage 13 and the winding portion 23.

With such a structure, the cooling efficiency of the winding portion 23 due to heat conduction by liquid helium can be reduced, so it is possible to further reduce the heater power required to turn off the switch. Further, for the above-mentioned reason, even if the refrigerant passage 13 does not have the valve 14, the temperature of the winding portion 23 can be easily raised, and the same effects as in the previous embodiment can be obtained.

Note that the present invention is not limited to the embodiments described above. For example, the material of the superconducting gate wire, the material of the piping forming the refrigerant passage, etc. may be determined as appropriate according to the specifications. Further, the valve is not necessarily necessary, and may be removed if the heating from the heater is sufficiently greater than the cooling by the refrigerant flowing through the refrigerant passage. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a schematic structure of a superconducting magnet according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the main structure of a superconducting switch body used in the magnet, and FIG. 3 is a cross-sectional view showing another embodiment. FIG. 4 is a sectional view showing the schematic structure of a conventional superconducting magnet. 1st... Magnet winding part, 12... Liquid helium container, 13... Refrigerant passage, 14... Gate valve,
15...Superconducting switch body, 16...Conducting wire, 21
...Superconducting gate wire, 22...Heater wire, 23...
- Winding part, 24... thermal insulation layer. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A superconducting switch comprising a superconducting gate wire, a winding portion around which a heater wire for heating the gate wire is wound, and a refrigerant passage cooling the winding portion by thermal conduction. . (2) The superconducting switch according to claim 1, wherein the coolant passage communicates with a liquid helium container for cooling the superconducting magnet. (3) The superconducting switch according to claim 1 or 2, wherein the refrigerant passage is equipped with a valve that opens and closes the passage, and this valve is closed when the switch is turned off.