JPH0231511B2 - - Google Patents

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 by immersing the switch body in liquid helium, as in the case of the superconducting magnet for magnetic levitation trains shown in FIG. Here, in the figure, 41 is a winding portion of the superconducting magnet body, 42 is a space in which liquid helium is placed (liquid helium container), and 45 is the superconducting switch body. Further, 48 is a container housing the switch main body 45, and is communicated with the liquid helium container 42.

However, this type of superconducting magnet has the following problems. That is, since the superconducting switch main body 45 is immersed in liquid helium, a large amount of heater power is required to maintain the switch in the OFF state. Further, as shown in FIG. 4, the liquid helium space is connected to the magnet winding section 41
In the case of an independent container structure, a conducting wire 46 connecting the superconducting wire for the magnet and the superconducting switch gate wire
However, the reliability of this seal portion 47 was insufficient.

[Purpose 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 that the windings of a superconducting switch are not directly cooled with a refrigerant, but are cooled through the walls of a cooling pipe.

That is, the superconducting switch according to the present invention includes a cooling pipe through which a refrigerant flows, a superconducting gate wire that is wound around the outer periphery of this cooling pipe and cooled through the wall of the cooling pipe, and this superconducting gate. The heater wire is wound around the outer periphery of the cooling pipe together with the gate wire to selectively heat the gate wire.

〔Effect of the invention〕

According to the present invention, the switch body is not directly cooled with liquid helium, but is cooled by thermal conduction through the tube wall of the cooling pipe, so that the switch body is not directly cooled with liquid helium.
The heater power required to maintain the OFF state 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. 11 in the diagram
is a magnet winding section in which a superconducting wire for magnet is wound; this winding section 11 is arranged around a liquid helium container 12 and is cooled by the liquid helium in the container. Liquid helium container 12
A cooling pipe 13 is connected to the cooling pipe 13, and liquid helium is also passed through the cooling pipe 13. Further, a gate valve 14 is provided in a part of the cooling pipe 13, and the flow of liquid helium within the cooling pipe 13 is controlled by this valve 14.

On the other hand, a superconducting switch body 15 is attached to the outer periphery of the cooling pipe 13. The switch main body 15 is constructed by winding a superconducting gate wire 21 and a heater wire 22 around the outer periphery of a cooling pipe 13, respectively, as shown in FIG. The superconducting gate wire 21 is cooled by thermal conduction by liquid helium flowing through the cooling pipe 13 and heated by the heater wire 22. In the figure, 16 indicates a conducting wire for connecting the winding section 11 and the superconducting gate wire 21, and 23 indicates a winding section around which the superconducting gate wire 21 and the heater wire 22 are wound.

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 cooling pipe 13, and the superconducting gate line 21 enters a superconducting state. On the other hand, when the switch is turned off, 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 cooling pipe 13 is filled with helium gas, and the temperature of the winding portion 23 is easily raised by the heater 22. Therefore, the switch can be turned off with less heater power.
It becomes possible to do so. In addition, in the case of this configuration, the superconducting switch body 15 is not immersed in liquid helium, but is placed on the outer periphery of the cooling pipe 13 through which liquid helium flows, so that an insulating airtight seal used at extremely low temperatures can be used. No longer needed.

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 cooling tube 13, so that by closing the valve 14, , 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 24 is provided between the cooling pipe 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 lowered, 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 cooling pipe 13 does not have the valve 14, the temperature of the winding portion 23 can be easily increased, 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 line, the material of the cooling pipe, etc. may be determined as appropriate according to 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 cooling pipe 13. In addition, various modifications can be made without departing from the gist of the present invention.

[Brief explanation of drawings]

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. DESCRIPTION OF SYMBOLS 11... Magnet winding part, 12... Liquid helium container, 13... Cooling pipe, 14... Gate valve, 15... Superconducting switch body, 16... Conducting wire, 21... Superconducting gate wire, 22... Heater Wire, 23... Winding portion, 24... Heat insulation layer.

Claims (1)

[Claims] 1. A cooling pipe through which a refrigerant flows, a superconducting gate wire that is wound around the outer periphery of this cooling pipe and cooled through the wall of the cooling pipe, and together with this superconducting gate wire. and a heater wire wound around the outer periphery of the cooling pipe to selectively heat the gate wire. 2. The superconducting switch according to claim 1, wherein the cooling pipe communicates with a liquid helium container for cooling the superconducting magnet. 3. Claim 1 or 2, wherein the cooling pipe is provided with a valve that opens and closes a refrigerant passage formed in the cooling pipe, and the valve is closed when a switch is turned off. Superconducting switch described in .