JPH07297026A - Superconducting coil - Google Patents

Abstract

PURPOSE:To prevent a resin lump from being generated in each radial duct when winding bundles are impregnated with a resin. CONSTITUTION:In a superconducting coil formed into a structure, wherein a superconductive wire is wound on a cylinder part 1A, which is provided with flange parts 1B projecting outward of the radical direction on both ends of the cylinder part 1A, of a spool 1, axial ducts 4A and 4B, which come into contact closely to winding bundles 3A and 3B of this superconductive wire and are turned to the axial direction of the part 1A, and radial ducts 2A and 2B, which come into contact closely to both ends in the axial directions of the bundles 3A and 3B and are turned to the radial direction of the part 1A, are provided in such a way that the ducts 4A and 4B and 2A and 2B are communicated with each other and the winding bundles 3a and 3B are impregnated with a resin, the inner wall, which is located on the opposite side to the bundles, of the duct 2B is slanted to the opposite side to the winding bundles as the inner wall goes outward of the radial direction of the part 1A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC superconducting coil used for energy storage superconducting coils and superconducting transformers.

[0002]

2. Description of the Related Art In order for a superconducting coil to maintain a superconducting state, temperature, current, and generated magnetic flux density are required to be smaller than their respective critical values. These critical values are critical temperature, critical current, and critical magnetic flux density, respectively. It is called. The superconducting state is maintained only when all of the temperature, current, and generated magnetic flux density are below their respective critical values, and if even one exceeds the critical value, the superconducting state transitions to the normal conducting state. Occurs. When the quench occurs, the magnetic energy stored in the superconducting coil is released as Joule heat due to the resistance of the superconducting wire when it is in the normal conducting state, causing a large amount of evaporation of expensive liquid helium as a refrigerant. In addition, the temperature of the superconducting wire forming the superconducting coil rises due to the Joule heat described above,
There is also a risk of burning. For this reason, it is well known that quench is harmful to superconducting coils.

In recent years, AC applications of superconducting coils, especially pulse applications, have been actively carried out in various places. When an alternating current (pulse) current is applied to the superconducting coil, heat is generated due to AC loss and the temperature rises. The AC loss is composed of hysteresis loss, coupling loss, and eddy current loss. The hysteresis loss is proportional to the magnitude of the generated magnetic flux density and does not depend on the changing speed of the generated magnetic flux density. On the other hand, the coupling loss is proportional to the square of the changing speed of the generated magnetic flux density and does not depend on the magnitude of the generated current density. Since the temperature rise due to these AC losses causes quenching of the superconducting coil, various measures have been taken to reduce the AC losses.

First, the hysteresis loss is proportional to the wire diameter of the superconducting element wire constituting the superconducting wire, in addition to the magnitude of the generated magnetic flux density. That is, the thinner the superconducting wire, the more the hysteresis loss can be reduced. Next, the coupling loss is proportional to the twist pitch of the superconducting wire in addition to the change in the generated magnetic flux density. Therefore, the coupling loss can be reduced by reducing the twist pitch as much as possible.

Further, the superconducting wire generally has a structure in which the superconducting element wire is embedded in a stabilizing material in order to bypass the current when it is quenched, but the coupling loss and the eddy current loss are It is also proportional to the electrical resistivity of the stabilizer between the strands. Therefore, in order to reduce the coupling loss and the eddy current loss, a metal having a high electric resistivity (for example, copper-nickel alloy or the like) may be used as the stabilizing material. However, if a metal having a too high electrical resistivity is used as a stabilizing material, when the superconducting wire is quenched and the current is bypassed, the temperature rise is large due to the high resistance value and there is a risk of burning, so it is easy The resistivity cannot be increased. In particular, when the energizing current value is large (1 kA or more), the stabilizing material is limited to copper or aluminum. Therefore, the superconducting wires are covered with copper, and the wires covered with copper are covered with a metal having a relatively high electric resistivity such as a copper-nickel alloy. By having a so-called three-layer structure, coupling loss and eddy current loss can be reduced.

At present, it is common to use a superconducting wire having this three-layer structure as a superconducting wire of an AC superconducting coil. However, there is a limit even if the diameter of the superconducting element wire is reduced or a high resistance metal barrier is inserted. Therefore, in order to realize a superconducting coil that can generate a large and rapidly changing magnetic flux density, liquid helium can flow into the winding by installing insulating materials such as FRP between the layers of the superconducting winding at intervals. The passage of
A method of providing a so-called cooling duct and actively cooling the inside of the superconducting coil to remove heat generation due to AC loss is used.

FIG. 3 is a one-sided sectional view showing the structure of a conventional superconducting coil. Cylindrical part 1 having an axial center at the left end of FIG.
The superconducting wire winding bundles 3A and 3B are wound around a winding frame 1 having flange portions 1B protruding outward in the radial direction at both upper and lower ends of A. The superconducting wire is fixed by impregnating the wound bundles 3A and 3B with resin. Axial ducts 4A, 4B are provided in close contact with the inner circumferential sides of the winding bundles 3A, 3B, and further radial ducts 20A, 20B are provided in close contact with the upper and lower end surfaces of the winding bundles 3A, 3B. There is.

FIG. 4 is a main part perspective view showing the structure of the apparatus shown in FIG. FIG. 4 shows the lower part of the device with the wraps removed for clarity of internal construction. Insulator 70
The radial duct 20B is formed by grooving B at an equal pitch. On the other hand, the axial duct is formed by interposing insulating duct pieces 4AA and 4BB between the winding bundles at equal pitches or between the winding bundle and the winding frame 1.

Returning to FIG. 3, the insulator 70A is also the insulator 70B.
Similarly to the above, grooves are formed at an equal pitch, and the upper and lower parts of the device are completely symmetrically inverted. To that end, the axial ducts 4A, 4B and the radial ducts 20A, 20B
And are in communication with each other. Liquid helium is made to flow from the bottom in the direction of arrow 5 along the route of radial duct 20B, axial ducts 4A and 4B, and radial duct 20A, and bundles 3A and 3B are cooled.

When a current is applied to the superconducting wire, the winding bundles 3A, 3
As the electromagnetic force, a radial force for increasing the radius and an axial force for contracting in the axial direction act on B. Therefore, the winding bundles 3A and 3B are impregnated with resin to prevent the superconducting wire from moving. Since the apparatus shown in FIG. 3 is impregnated with resin, the entire apparatus is once vacuum-impregnated with resin. After that, the resin is removed with the central axis of the device being vertical. The resin in the radial ducts 20A, 20B and the axial ducts 4A, 4B flows in the directions of the arrows 6A, 6B and escapes to the lower portion, where cooling ducts are formed. On the other hand, the resin impregnated in the winding bundles 3A and 3B does not immediately flow out due to the narrow gap in the superconducting wire. If the device is heat-treated in that state, the resin is cured and the winding bundles 3A, 3B
Is firmly solidified.

[0011]

However, the conventional apparatus as described above has a problem that when the resin is impregnated with the resin, the resin is accumulated in the lower radial duct. In FIG. 3, when the impregnated resin is removed, the resin flows downward in the axial ducts 4A and 4B. After that, the resin falls in the lower radial duct 20B and flows outward in the radial direction. However, since the radial duct 20B is horizontally arranged, the resin flow is extremely bad. Therefore, as shown in FIG. 3 or 4, the resin reservoir 9 is likely to be formed near the lower portions of the axial ducts 4A and 4B. When a large amount of this resin reservoir 9 is left as it is and the entire apparatus is heated, the cooling duct is crushed.
As a result, the cooling efficiency of the device with liquid helium decreases, which may be a cause of quenching.

An object of the present invention is to prevent resin accumulation in the device.

[0013]

In order to achieve the above object, according to the present invention, a superconducting wire is wound around a cylindrical portion of a bobbin provided with flange portions projecting radially outward at both ends of the cylindrical portion. The axial duct that is in close contact with the winding bundle of the superconducting wire and faces in the axial direction of the cylindrical portion and the radial duct that is in close contact with both axial ends of the winding bundle and that faces in the radial direction of the cylindrical portion communicate with each other. And the winding bundle is impregnated with resin, at least the inner wall of the radial duct on the side opposite to the side of the winding bundle is inclined toward the side of the non-winding bundle as it goes outward in the radial direction. .

Further, in such a structure, the inner walls of the both side ducts on the non-winding bundle side may be inclined toward the non-winding bundle side as they go outward in the radial direction.

[0015]

According to the structure of the present invention, at least one inner wall of the radial duct on the side opposite to the winding bundle is inclined toward the side opposite to the winding bundle as it goes outward in the radial direction. When the resin impregnated into the device is removed, the central axis of the device is set to be vertical, and the radial duct with the inner wall inclined is located at the bottom of the bundle. As a result, even if the resin in the axial duct falls to the lower radial duct, the radial duct has an inclination,
Smoothly flows radially outward. Therefore, the resin is not accumulated in the radial duct, and the cooling efficiency is significantly improved.

In such a structure, the inner walls of the two radial ducts on the non-winding bundle side are inclined toward the non-winding bundle side as they go outward in the radial direction. The direction in which the device is placed when removing the resin impregnated into the device must be such that its central axis is vertical, but there is no restriction on the vertical relationship of the radial ducts. That is, even if any of the radial ducts is located at the lower part, the inner wall is inclined, so that the resin is not accumulated. Therefore, there is no need to worry about the vertical relationship of the device when removing the resin, and no error occurs. In addition, the same shape of insulator can be used for forming the upper and lower radial ducts, and parts can be shared.

[0017]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is a one-sided sectional view of a superconducting coil according to an embodiment of the present invention. As the upper and lower radial ducts 2A and 2B both go outward in the radial direction, the unwinding bundle 3A,
It has slopes 8A and 8B that are inclined toward the 3B side. FIG. 2 is a perspective view of an essential part showing the configuration of the apparatus shown in FIG. FIG. 2 shows the interior of the device with the wraps removed for clarity and only the bottom of the device is shown. The radial duct 2B is formed by grooving the insulator 7B at an equal pitch.

Returning to FIG. 1, the insulator 7A is also grooved at an equal pitch like the insulator 7B, and the upper and lower parts of the device are completely symmetrically inverted. The other structure is the same as the conventional structure described in FIGS. The same portions will be denoted by the same reference numerals, and repeated description will be omitted. In FIG. 1, when the impregnated resin is removed with the central axis of the device vertical, the resin flows in the directions of arrows 6A and 6B, but the radial duct 2B
Since there is a slope 8B, the resin smoothly flows out to the right. Therefore, no resin accumulation occurs in the radial duct 2B.

The upper radial duct 2A in FIG. 1 also has a slope 8A. When the radial duct 2B is at the bottom, the slope 8A has no function. However, when the device is turned upside down and the radial duct 2A is arranged in the lower part, the slope 8A functions to smoothly flow out the resin. If the slope of the inner wall surface of the radial duct is provided only in the lower portion, if the radial duct having the inclined surface is set as the upper portion and the resin is removed, a resin pool may be formed and a defective product may be produced. Radial ducts 2A, 2B above and below the device
By forming the same slopes 8A and 8B on the first and second sides, it is not necessary to check the direction of the device when removing the impregnated resin, and a mistake never occurs. Further, since the upper and lower parts are composed of the insulators 7A and 7B having the same shape, the parts are made common and the cost is reduced.

Further, in FIG. 1, the larger the angle of the slope 8B (the angle which opens downward in the radial direction), the easier the resin flows, so that the resin accumulation is less likely to occur.
However, considering the workability of the insulator 7B, the angle is preferably 15 to 45 degrees.

[0021]

As described above, according to the present invention, the inner wall of the at least one radial duct on the side opposite to the winding bundle is inclined toward the side opposite to the winding bundle as it goes outward in the radial direction. As a result, the resin is not accumulated in the radial duct, and the cooling efficiency of the device is significantly improved. Further, in such a configuration, the inner wall of each of the radial ducts on the non-winding bundle side is inclined toward the non-winding bundle side as it goes outward in the radial direction. As a result, there is no need to worry about the vertical relationship of the device when removing the resin, and no error occurs. In addition, the insulators for forming the upper and lower radial ducts are also provided with the same shape, so that the parts can be shared and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of a superconducting coil according to an embodiment of the present invention.

FIG. 2 is a perspective view of a main part showing the configuration of the apparatus shown in FIG.

FIG. 3 is a sectional view of one side of a conventional superconducting coil.

FIG. 4 is a perspective view of a main part showing the configuration of the apparatus shown in FIG.

[Explanation of symbols]

1: winding frame, 1A: cylindrical portion, 1B: brim portion, 2A, 2B:
Radial duct, 3A, 3B: Winding bundle, 4A, 4B: Axial duct

Claims (2)

[Claims] 1. A superconducting wire is wound around a cylindrical portion of a bobbin having a collar portion projecting outward in the radial direction at both ends of the cylindrical portion, and the superconducting wire is closely contacted with a bundle of the superconducting wire in the axial direction of the cylindrical portion. The axial duct that faces and a radial duct that closely contacts the axial ends of the winding bundle and that faces the radial direction of the cylindrical portion are provided in communication with each other, and the winding bundle is resin-impregnated, at least A superconducting coil characterized in that the inner wall of the one radial duct on the side opposite to the winding bundle is inclined toward the side opposite to the winding bundle as it goes radially outward. 2. The superconducting coil according to claim 1, wherein the inner walls of the radial ducts on the non-winding bundle side are inclined toward the non-winding bundle side as they go outward in the radial direction.