JPH0640530B2 - Superconducting magnet for magnetic levitation train - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a superconducting magnet for a magnetic levitation train, and in particular,
The present invention relates to a superconducting magnet for a magnetic levitation train, which is required for small size, light weight, and low invasion heat property for mobile use.

[Conventional technology]

FIGS. 3 and 4 are schematic cross-sectional views showing a conventional superconducting magnet for a magnetic levitation train, which is shown in P489 of a cryogenic engineering handbook (published by Uchida Lao Tsuruga Shinsha Co., Ltd.).

In the figure, reference numeral (1) is a superconducting coil, (2) is liquid helium in which the superconducting coil (1) is immersed to cool the superconducting coil (1), and (3) is the superconducting coil (1) and the liquid. Helium tank containing helium (2), (4) radiant heat shield surrounding helium tank (3) to shield radiant heat, (5) vacuum tank for constituting vacuum section (7) for heat insulation , (8) show magnetic lines of force generated by the superconducting coil (1). Also,
(10) is a support member for supporting the superconducting coil (1) and the radiant heat shield (4), and (11) is a multi-layer insulation for heat insulation.

Next, the operation of the conventional device will be described.

When a current is passed through the superconducting coil (1) in the permanent current mode,
Depending on the polarity, for example, as shown in FIG. 4, a magnetic field of magnetic force lines (8) is generated.

Liquid helium (2) cools the superconducting coil (1), and the vacuum tank (5), the vacuum section (7), the multilayer insulation (11) and the radiant heat shield (4) are helium tanks. The amount of heat entering (3) is reduced to suppress the vapor of liquid helium (2) to a minimum.

The superconducting coil (1) and the radiant heat shield (4) are supported by a support member (10).

The helium supply / discharge port, the current lead, the permanent current switch, and the like have no particular relation to the present invention, and therefore their explanations are omitted.

Further, usually, austenitic stainless steel is used as a constituent material of the helium tank (3), and an aluminum material or a copper material having a large thermal conductivity is used for the radiant heat shield (4).

Further, in a superconducting magnet for a magnetic levitation train, which is particularly required to have small size, light weight and low penetration characteristics, a helium tank (3)
And the radiant heat shield (4) and the radiant heat shield (4) and the vacuum chamber (5) are very narrow, and depending on the location, there are some portions that are only a few mm apart.

When the superconducting coil (1) undergoes superconducting breakdown (quenching), the current (12) flowing through the superconducting coil (1) shown in FIG. 5 tends to be rapidly attenuated. In this way, when the current (12) flowing through the superconducting coil (1) is attenuated, the magnetic flux generated by the superconducting coil (1) is also attenuated. As a result, according to Faraday's law of electromagnetic induction, an induced voltage is applied to the radiant heat shield (4) arranged outside the superconducting coil (1), and as a result, the magnetic flux attenuation shown in FIG. 5 is prevented. A current (13) flows in any direction. here,
Since the current (12) of the superconducting coil (1) and the current (13) flowing through the radiant heat shield (4) are in the same direction,
The superconducting coil (1) and the radiant heat shield (4) have electromagnetic forces that attract each other. Due to this electromagnetic force, the radiant heat shield (4) having low rigidity is pulled and deformed in the direction of the helium tank (3) which is strongly manufactured by stainless steel.

[Problems to be solved by the invention]

The conventional superconducting magnet for a magnetic levitation train is configured as described above, and when this superconducting coil causes superconducting breakdown during excitation, a large current flows through the radiant heat shield as described above, and the radiant heat shield generated at that time. The radiant heat shield deforms toward the helium tank due to the electromagnetic force applied to
In a superconducting magnet for a magnetic levitation train, where the distance between the radiant heat shield and the helium tank is narrow, the radiant heat shield comes into contact with the helium tank, and as a result, the evaporation amount of liquid helium becomes excessive and it does not function as a superconducting magnet. There was a problem.

To address these problems, widening the distance between the radiant heat shield and the helium tank deteriorates the magnetic performance of the superconducting magnet, and strengthening the structure of the radiant heat shield increases the weight of the entire superconducting magnet. However, if the support of the radiant heat shield is strengthened, the heat that penetrates through the support increases and the amount of helium vaporized increases. Therefore, such measures cannot be taken.

This invention was made in order to solve the above problems, without widening the distance between the radiant heat shield and the helium tank, and without strengthening the support of the radiant heat shield or the radiant heat shield. , To obtain a superconducting magnet for a magnetic levitation train that does not cause deformation of the radiant heat shield when the superconducting is destroyed.

[Means for solving problems]

The superconducting magnet for a magnetic levitation train according to the present invention has a helium tank provided with a conductor forming a closed loop circuit.

[Action]

The superconducting magnet for the magnetic levitation train according to the present invention is
Since a conductor forming a closed loop circuit is provided in the helium tank, in the case of superconducting breakdown, a current flows through the conductor provided in the helium tank, and a large current does not flow through the radiant heat shield, thus adding to the radiant heat shield. Electromagnetic force is small,
As a result, the radiant heat shield does not deform.

On the other hand, a large current flows to the conductor provided in the helium tank and a large electromagnetic force is applied to the conductor, but since the conductor is firmly supported by the helium tank, it is not deformed.

〔Example〕

The present invention will be described below with reference to the drawings showing an embodiment thereof.

In FIG. 1, reference numeral (21) is a copper plating layer provided on the surface of the helium tank (3) which is a conductor forming a closed loop circuit provided in the helium tank (3).

Since the other structures are the same as those of the conventional superconducting magnet shown in FIGS. 3 and 4, the description thereof will be omitted here.

Since the superconducting magnet for a magnetic levitation train according to the present invention is configured as described above, when the superconducting coil (1) causes a superconducting breakdown, a rapid current ( Due to the attenuation of 12), a dielectric voltage is applied to the surrounding members, and a current that tries to prevent the attenuation of the training magnetic flux of the superconducting coil (1) is generated, but this large current (22) is the helium tank (3). Spills on the copper plating layer provided on the surface of the glass, resulting in radiant heat shield (4)
Does not flow a large current. Therefore, the electromagnetic force applied to the radiant heat shield (4) is small, and accordingly, the radiant heat shield (4) does not deform.

In addition, a copper plating layer (21) through which a large current (22) flows
Of course, since it is fixed to the helium tank (3), it does not deform.

In the above embodiment, the conductor forming the closed loop circuit provided in the helium tank (3) is the helium tank and the conductor on which the entire surface of (3) is plated with copper.
Not limited to this, the current (22) flowing through the helium tank (3)
The copper plating may be applied only to the portion along the flow path of, and in this case, it is advantageous in terms of weight.

Further, not only copper but also aluminum plating may be used.

Further, in the above-mentioned embodiment, the installation of the conductor in the helium tank is shown by the plating treatment, but not limited to the plating treatment, the helium tank (3) itself is made of a copper or aluminum cladding plate such as a cladding stainless steel plate. Alternatively, a copper or aluminum plate-like conductor such as a plate or a thin plate or a foil member may be attached to the surface of the helium tank along a path through which the current (22) flows in a closed loop to form a helium tank (3). It may be fixed, and in any of the above cases, the same effect as that of the above embodiment can be obtained.

〔The invention's effect〕

As described above, according to the present invention, since the current path is formed by providing the conductor forming the closed loop circuit in the helium tank, even when the superconducting breakdown occurs, a large current flows through the conductor and a large radiation heat shield is generated. No electric current flows, so that a large electromagnetic force is not applied to the radiant heat shield, and thus the radiant heat shield does not deform, and as a result, it is necessary to increase the distance between the radiant heat shield and the helium tank, or the radiant heat shield. There is no need to strengthen the support and the support thereof, and there is an effect that a superconducting magnet for a magnetic levitation train can be obtained in which the radiant heat shield does not contact the helium tank.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a superconducting magnet according to an embodiment of the present invention, FIG. 2 is an explanatory view of a current generated at the time of superconducting breakdown of FIG. 1, and FIG. 3 is a schematic transverse sectional view of a conventional superconducting magnet. FIG. 4 is a schematic vertical sectional view taken along line IV-IV of FIG. 3, and FIG. 5 is an explanatory diagram of a generated current at the time of superconducting breakdown of FIG. (1) …… Superconducting coil, (2) …… Liquid helium,
(3) …… Helium tank, (4) …… Radiant heat shield,
(5) ... vacuum chamber, (21) ... closed loop circuit conductor (copper plated layer). In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (5)

[Claims] 1. A superconducting magnet for a magnetic levitation train, characterized in that a helium tank containing a superconducting coil immersed in liquid helium is provided with a conductor forming a closed loop current circuit. 2. The superconducting magnet for a magnetic levitation train according to claim 1, wherein the conductor provided in the helium tank is either copper or aluminum. 3. The superconducting magnet for a magnetic levitation train according to claim 1 or 2, wherein the conductor provided in the helium tank is provided by plating. 4. The magnetic levitation train according to claim 1 or 2, wherein the conductor provided in the helium tank is provided by constructing the helium tank by the cladding stainless steel of the conductor. Superconducting magnet. 5. The superconducting magnet for a magnetic levitation train according to claim 1 or 2, wherein the conductor provided in the helium tank is a plate-like conductor fixedly provided in the helium tank.