JP3202389B2 - Superconducting coil device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil device having a winding frame.

[0002]

2. Description of the Related Art Superconducting coil devices are roughly classified into several types according to their structure. Those having a winding frame can also be classified as one type. Many of these types of superconducting coil devices are for large currents.The superconducting coil is formed by directly wrapping the superconducting conductor around the outer periphery of the bobbin. It is known that an element is formed and a coil element is sequentially formed outside a coil element of an innermost layer via a spacer, thereby forming a superconducting coil having a plurality of layers.
In order to prevent eddy currents from being generated in the winding frame for AC or pulse, a winding frame made of glass fiber reinforced plastic (hereinafter abbreviated as GFRP) using an epoxy resin as a matrix is usually used. Have been.

[0003] Such a superconducting coil device is used in a state where the entire superconducting conductor forming the superconducting coil is immersed in a cryogenic liquid represented by liquid helium in order to keep the temperature below the superconducting transition temperature. You.

However, the conventional superconducting coil device having a GFRP winding frame has the following problems. That is, as shown in FIG. 9 (a), the superconducting conductor 2 is wound around
Is immersed in a cryogenic liquid, the glass fiber and the epoxy resin constituting the bobbin 1 have a positive coefficient of thermal expansion.
Is shrunk in the axial direction and also shrunk in the radial direction as shown by thick arrows A and B in the figure. On the other hand, superconducting conductor 2 constituting superconducting coil body 3 is also formed of a metal material having a positive coefficient of thermal expansion. For this reason, the superconducting coil main body 3 contracts in the axial direction and contracts in the radial direction as shown by thick arrows C and D in the figure. As described above, when the superconducting coil device 4 is simply immersed in the cryogenic liquid, the bobbin 1 and the superconducting coil main body 3 are thermally contracted in the same form, so that there is no possibility that the connection between them becomes loose. Absent.

However, when a current is applied to the superconducting coil main body 3 in a state where the superconducting coil main body 3 is cooled to a very low temperature, the superconducting coil main body 3 is moved by thick arrows C 'and E in FIG. As shown, the amount of contraction in the axial direction is further increased, and the contraction in the radial direction is reversed. For this reason, the superconducting coil main body 3 is loosened in the fixed state with respect to the winding frame 1. When loosening occurs, the whole or a part of superconducting coil main body 3 becomes easy to move during energization. Even slight movement generates frictional heat. Since the cryogenic liquid represented by liquid helium has an extremely small specific heat, it becomes difficult to quickly absorb frictional heat with the cryogenic liquid, and as a result, the superconducting conductor 2 undergoes a normal conduction transition (quenching). there were.

[0006]

SUMMARY OF THE INVENTION As described above, GFRP
In the conventional superconducting coil device equipped with a winding frame made of
There was a problem that quenching cannot be essentially avoided. Therefore, an object of the present invention is to provide a superconducting coil device that can solve the above-described problems.

[0007]

In order to achieve the above object, a typical example of the present invention comprises a winding frame and a superconducting coil body formed by winding a superconducting conductor around the outer periphery of the winding frame. In the superconducting coil device used at extremely low temperatures, the winding frame orients the roving of the high-strengthened polyethylene fiber in a range of ± 40 degrees to ± 80 degrees with respect to the axis of the superconducting coil body. It is characterized by being formed of a fiber reinforced plastic.

[0008] As the polyethylene fiber subjected to the high-strength treatment, for example, a polyethylene filament containing a solvent for polyethylene is subjected to a stretching treatment at a temperature between the swelling point and the melting point of polyethylene to increase the strength. Although the thing etc. can be used, the thing strengthened by other methods may be used.

[0009]

The detailed method for producing a high-strength polyethylene fiber is described in, for example, JP-A-55-137506 and JP-A-56-15408.

The high-strength polyethylene fiber (hereinafter abbreviated as DF) has a unique property that, unlike ordinary glass fiber or ceramic fiber, elongates in the fiber direction as the temperature becomes lower. ing. That is, the fiber-reinforced plastic molded body made of this DF is
As shown in FIG. 2, the fiber has a negative coefficient of thermal expansion in the fiber direction, and has a positive coefficient of thermal expansion in the radial direction. In addition,
FIG. 2 shows the relationship between the temperature and the amount of heat shrinkage of various fiber-reinforced plastics unidirectionally reinforced (UD).

The roving of this DF is wound using an epoxy resin as a matrix, and as shown in FIG.
For example, when a cylindrical plastic molded body (hereinafter abbreviated as DFRP molded body) 5 reinforced with
The dimensional change of the DFRP molded body 5 in the radial direction and the axial direction with respect to the temperature depends on the winding angle θ as shown in FIG.

FIG. 4 shows the relationship. X in the figure
a indicates the thermal expansion coefficient of the DFRP molded body in the axial direction, and Xr
Indicates the coefficient of thermal expansion of the DFRP molded body in the radial direction. In FIG. 4, as a reference example, the thermal expansion coefficient in the axial direction of the GFRP molded body is indicated by Ya, and
The coefficient of thermal expansion in the radial direction of the compact is indicated by Yr.
As can be seen from FIG. 4, in the case of the DFRP molded body, even if the matrix used has a positive coefficient of thermal expansion,
Due to the characteristics of the DF, when the winding angle θ is in the range of ± 40 degrees to ± 80 degrees, the coefficient of thermal expansion in the radial direction of the DFRP molded body is a large negative value, and conversely, the coefficient of thermal expansion in the axial direction is a large positive value. Becomes Therefore, in the DFRP molded body in which the winding angle θ is set in the above range, the DFRP molded body expands (expands) largely in the radial direction and contracts largely in the axial direction as the temperature decreases.

On the other hand, in the case of a GFRP molded body, the GF itself has a positive coefficient of thermal expansion in any direction. For this reason, no matter what value the winding angle θ is set to, the thermal expansion coefficients in the radial and axial directions of the GFRP molded body are positive, and the characteristics of the DFRP molded body cannot be obtained.

In the superconducting coil device according to the present invention, the DF roving having the above-described characteristics is wound by a DFRP formed by orienting the roving of the DF in a range of ± 40 degrees to ± 80 degrees with respect to the axis of the superconducting coil body. A frame is used. Therefore, the winding frame can exhibit ideal characteristics for preventing quench.

FIG. 5 is a diagram for explaining the reason. That is, as shown in FIG. 5 (a), the superconducting conductor 1 is placed on a DFRP winding frame 11 in which the winding angle θ is set in the above range.
When the superconducting coil device 14 in which the superconducting coil body 13 is formed by winding the superconducting coil 2 is immersed in a cryogenic liquid, the bobbin 11 shrinks greatly in the axial direction as shown by the thick arrows J and K in the figure and simultaneously Inflates significantly. on the other hand,
The superconducting coil main body 13 contracts in the axial direction and contracts in the radial direction as indicated by thick arrows C and D in the figure.

As described above, the winding frame 11 and the superconducting coil main body 13 expand and contract in a radially opposite relationship, and the amount of contraction of the winding frame 11 in the axial direction exceeds that of the superconducting coil main body 13. Therefore, when immersed in the cryogenic liquid as described above, the bonding strength between the bobbin 11 and the superconducting coil main body 13 is in a greatly enhanced state as compared with the time of manufacture.

When a current is applied to the superconducting coil body 13 in a state where the superconducting coil body 13 is cooled to an extremely low temperature as described above, the superconducting coil body 13 is moved by the electromagnetic force generated by the current as shown in FIG.
As shown by bold arrows C 'and E, the amount of contraction in the axial direction further increases, and expands in the radial direction. That is, the superconducting coil body 13 contracts and expands in a direction in which the coupling strength between the winding frame 11 and the superconducting coil body 13 is reduced.

However, since the bonding strength between the bobbin 11 and the superconducting coil body 13 is greatly enhanced at the stage of being immersed in the cryogenic liquid, even if the superconducting coil body 13 contracts or expands, The coupling strength between the frame 11 and the superconducting coil main body 13 only returns to the same level as at the time of manufacture. Therefore, even if a current is applied to the superconducting coil main body 13, the winding
There is no looseness in the connection between the superconducting coil body 1 and the superconducting coil body 13, and eventually, it is possible to suppress the occurrence of quench caused by the looseness.

[0019]

【Example】

Embodiment 1 FIG. 1 shows a superconducting coil device according to one embodiment of the present invention. This superconducting coil device is roughly divided into
It comprises a winding frame 21 and a superconducting coil body 23 formed by winding a superconducting conductor 22 around the winding frame 21.

The bobbin 21 is formed of DFRP, has flanges 24a and 24b at both ends, and has a spiral groove 25 on the outer surface of a portion located between the flanges 24a and 24b. The flanges 24a, 24
b, on the outer surface of the portion located between
A plurality of flow grooves 26 extending in the axial direction are formed in the circumferential direction, and each of the flow grooves 2 is formed in the flanges 24a and 24b.
6 is formed with a hole 27 communicating with the end. The superconducting conductor 22 is wound in a solenoid shape with a certain tension so that a part thereof is fitted into the spiral groove 25.

Here, a specific example will be described. First, an ultra high molecular weight polyethylene fiber (Dyneema, SK-60, manufactured by Toyobo Co., Ltd.) having a strength of 35 g / d was prepared as a filament, and an epoxy resin was prepared as a matrix, as shown in FIG. 3 (b). DF was impregnated with a resin and wound around a mandrel such that the winding angle θ was ± 65 degrees to form a cylindrical body. This one
After holding at 00 ° C. for 2 hours, it was held at 130 ° C. for 3 hours to cure, and the fiber volume content was 65% as shown in FIG.
% DFRP molded article was obtained.

Next, flanges 24a and 24b are formed on both ends of the DFRP molded body by machining, and the outer surface of a portion located between the flanges 24a and 24b has a depth of 3 mm, an opening angle of 90 degrees and a V-shaped cross section. Spiral grooves 25 are formed at a pitch of 8 mm, followed by a flow groove 26 deeper than the spiral grooves 25, having a depth of 4 mm, a width of 4 mm, and extending in the axial direction.
Are formed at a pitch of 10 degrees in the circumferential direction, and holes 27 are formed in the flanges 24a and 24b at the ends of the respective flow grooves 26 in a one-to-one relationship.

Thus, the inner diameter is 80 mm and the outer diameter is 10 mm.
A winding frame 21 having a length of 0 mm and a length of 150 mm in the axial direction was obtained. In order to be accommodated in the spiral groove 25 of the winding frame 21, the wire diameter is 1.
An 8 mm superconducting conductor 22 was spirally wound with a tension of 50 kg to complete a superconducting coil device.

On the other hand, as a reference example, a GFRP bobbin having the same dimensions and the same shape was prepared, and a wire diameter of 1.8 was also used.
The superconducting coil device was completed by winding a superconducting conductor having a thickness of 50 mm with a tension of 50 kg.

The two superconducting coil devices thus obtained were immersed in liquid helium, and the quench currents were measured. As shown in FIG. 6, in the reference example using a GFRP winding frame, 1000 A was used. Quenched with However, in the present embodiment using the DFRP winding frame in which the winding angle θ is set in the above relation, the winding angle θ is 30% larger than the reference example.
Electricity could be supplied up to 300A.

Also, when the strain generated in the bobbin during cooling was measured, the bobbin made of GFRP was 0.27 mm in the radial direction.
While it contracted 0.25 mm in the axial direction, it was confirmed that the winding frame made of DFRP expanded 1.2 mm in the radial direction and contracted 0.82 mm in the axial direction.

As described above, when the winding frame made of DFRP in which the winding angle θ is set in the relationship described above is used, at extremely low temperatures,
The bobbin can be contracted in the axial direction and expanded in the radial direction, and the contraction and expansion can prevent loosening of the connection between the bobbin and the superconducting coil body. As a result, occurrence of quench caused by loosening can be reduced.

As in this embodiment, a spiral groove 25 having a V-shaped cross section is provided on the outer peripheral surface of the winding frame 21.
5, the superconducting conductor 22 is wound around the bobbin 21 so that the superconducting conductor 22 can be automatically positioned at the center of the V-shape at the time of winding, and the winding operation can be facilitated. Also, it is possible to make the displacement less likely to occur. Further, by setting the pitch of the spiral groove 25 larger than the diameter of the superconducting conductor 22,
Electrical insulation between the superconducting conductors 22 can be reliably ensured. Embodiment 2 FIG. 8 shows a superconducting coil device according to another embodiment of the present invention.

This superconducting coil device is roughly divided into
The winding frame 31 includes a superconducting coil body 34 formed by winding a superconducting conductor 33 around the winding frame 31 via a spacer 32 in a two-layer structure.

The bobbin 31 is formed by DFRP manufactured under the same conditions as the bobbin of the first embodiment. Flanges 35a and 35b are formed at both ends of the winding frame 31, and a plurality of axially extending flow channels 36 are formed in the outer surface of a portion located between the flanges 35a and 35b in the circumferential direction. Holes 37 are formed in the flanges 35a and 35b so as to communicate with the ends of the respective flow grooves 36 and the gaps between the spacers 32 which are spaced apart in the circumferential direction.

The superconducting coil main body 34 has an innermost layer 39 formed by winding a superconducting conductor 33 and an insulating dummy wire 38 around the outer peripheral surface of the winding frame 31 together with a constant tension in a parallel solenoid shape. The inner layer 39 is composed of a next layer 40 formed by winding a superconducting conductor 33 and an insulating dummy wire 38 together with a constant tension on a peripheral surface of the innermost layer 39 via a spacer 32 in a parallel solenoid shape.

As each of the spacers 32, a unidirectional reinforced prepreg using a DF having an epoxy resin as a matrix is prepared in advance and alternately formed at ± 65 degrees, for example, 25 degrees.
After laminating the layers and winding them, the mold is formed.
After being held at a temperature of 130 ° C. for 2 hours, a material cured at a temperature of 130 ° C. for 3 hours is used.

With this configuration, when cooled to an extremely low temperature, the bobbin 31 contracts in the axial direction, and the bobbin 31 and the spacer 32 expand in the radial direction. Due to the contraction and expansion, it is possible to prevent the loosening of the connection between the winding frame 31 and the superconducting coil main body 34 and the connection between the innermost layer 39 and the next layer 40. As a result, the occurrence of quench caused by loosening can be reduced.

The present invention is not limited to the embodiment described above. That is, in the embodiment shown in FIG. 8, the spacers separated in the circumferential direction are used. However, when cooling can be sufficiently ensured, the unidirectional reinforced prepreg formed by DF on the outer peripheral surface of the innermost layer 39 is taken into consideration in the orientation. A plurality of layers may be stacked and cured to form a spacer.

[0035]

As described above, according to the present invention, the superconducting coil main body can be firmly fixed by effectively utilizing the thermal deformation of the bobbin or the bobbin and the spacer that occurs at an extremely low temperature, and the quench can be achieved. Can be reduced.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view of a superconducting coil device according to one embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA in FIG.

FIG. 2 is a graph showing the amount of heat shrinkage of a fiber-reinforced plastic molded article made of a polyethylene fiber and various fibers subjected to a high strength treatment (however, a metal has its own characteristics).

FIG. 3A is a perspective view showing an example of a DFRP molded body,
(b) is a diagram for explaining the winding angle when manufacturing the same molded body.

FIG. 4 is a diagram showing a relationship between a winding angle of a DFRP molded body and a GFRP molded body and a coefficient of thermal expansion.

FIG. 5 is a diagram for explaining the operation of the superconducting coil device according to the present invention.

FIG. 6 is a diagram for explaining a quench characteristic of the superconducting coil device according to the present invention.

FIG. 7 is a diagram showing a magnetic field dependence of a critical current and a load curve of a coil of the superconducting coil device according to the present invention.

8A is a longitudinal sectional view of a superconducting coil device according to another embodiment of the present invention, and FIG. 8B is a sectional view taken along line BB in FIG.

FIG. 9 is a diagram for explaining a problem of a conventional superconducting coil device using a winding frame made of GFRP.

[Explanation of symbols]

21, 31 ... winding frame 22, 33 ... superconducting conductor 23, 34 ... superconducting coil body 25 ... spiral groove 32 ... spacer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiro Kashima 2-1-1 Katata, Otsu-shi, Shiga Prefecture Inside Toyo Spinning Co., Ltd. (72) Inventor Hidetomo Inui 2-1-1 Katata, Otsu-shi, Shiga Prefecture (72) Toichi Okada, Inventor Toichiichi Okada 8-1-1 Mihogaoka, Ibaraki City, Osaka Prefecture (72) Inventor Shigehiro Nishijima 3-50, Hirono Gongen, Hatano-cho, Kameoka-shi, Kyoto (56) References JP-A-4-179103 (JP, A) JP-A-60-173808 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 6/00-6/06

Claims (5)

(57) [Claims] A superconducting coil body formed by winding a superconducting conductor around an outer periphery of the winding frame, wherein the winding frame is made of high-strength polyethylene. A superconducting coil device comprising a fiber reinforced plastic in which fiber rovings are oriented within a range of ± 40 degrees to ± 80 degrees with respect to an axis of the superconducting coil main body. 2. A winding frame, and a superconducting conductor is wound around an outer periphery of the winding frame to form a coil element of an innermost layer, and a coil element is sequentially formed outside of the coil element of the innermost layer via a spacer. A superconducting coil device comprising a superconducting coil body having a multi-layer structure and used at cryogenic temperatures, wherein the bobbin and the spacer are formed by roving high-strength polyethylene fibers with respect to the axis of the superconducting coil body. A superconducting coil device formed of a fiber reinforced plastic oriented in a range of 40 degrees to ± 80 degrees. 3. The superconducting coil device according to claim 1, wherein the high-strength polyethylene fiber has a negative coefficient of thermal expansion (elongates as the temperature decreases). 4. The superconducting coil device according to claim 1, wherein the winding frame has a spiral groove for accommodating and fixing the superconducting conductor on an outer peripheral surface portion. 5. The winding frame according to claim 1, further comprising a passage for guiding a cryogenic liquid for cooling the superconducting conductor on an outer peripheral surface portion. Superconducting coil device.