Superconducting coil

Abstract

A superconducting coil (10) comprises: a coil body (12) that is formed by winding a superconducting wire (18); and an impregnation material (16) that contains a photocurable resin material, at least a portion of the coil body (12) being impregnated with the impregnation material (16). The superconducting wire (18) is provided with a light-transmitting coating (18b) that transmits at least some light for curing the photocurable resin material when irradiated with said light. Additionally or alternatively, the superconducting coil (10) comprises a winding frame (14) around which the superconducting wire (18) is wound, at least a portion of the wiring frame (14) being formed from a light-transmitting material that transmits at least some light for curing the photocurable resin material when irradiated with said light.

Description

superconducting coil

[0001] The present invention relates to a superconducting coil.

[0002] A superconducting coil is formed by winding a superconducting wire. The wound superconducting wire is impregnated with a synthetic resin material to fix the superconducting wire and to improve the mechanical strength of the superconducting coil.

[0003] Japanese Patent Application Publication No. 4-91407

[0004] Generally, a thermosetting resin is used to impregnate the wound superconducting wire. The thermosetting process can take, for example, several hours to several tens of hours or more. Therefore, the manufacturing of a superconducting coil takes a long time.

[0005] An exemplary object of an embodiment of the present invention is to provide a superconducting coil that can be manufactured in a short period of time.

[0006] According to one aspect of the present invention, a superconducting coil includes a coil body formed by winding a superconducting wire, and an impregnating material containing a photocurable resin material and impregnating at least a portion of the coil body. The superconducting wire includes a light-transmitting coating that transmits at least a portion of light when irradiated with light that cures the photocurable resin material.

[0007] According to one aspect of the present invention, a superconducting coil comprises a coil body formed by winding superconducting wire, an impregnating material containing a photocurable resin material and impregnating at least a portion of the coil body, and a reel around which the superconducting wire is wound, at least a portion of which is formed from an optically transparent material that transmits at least a portion of light when irradiated with light that hardens the photocurable resin material.

[0008] According to the present invention, it is possible to provide a superconducting coil that can be manufactured in a short time.

[0009] Fig. 2(a) is a diagram schematically showing a superconducting coil according to an embodiment. Fig. 2(a) is a diagram schematically showing a hardening process of an impregnating material in a superconducting coil according to a comparative example, and Fig. 2(b) is a diagram schematically showing a hardening process of an impregnating material in a superconducting coil according to an embodiment. Fig. 2(b) is a diagram schematically showing a superconducting coil according to another embodiment. Fig. 2(c) is a diagram schematically showing a hardening process of an impregnating material in a superconducting coil according to another embodiment. Fig. 3 is a diagram schematically showing a modified example of the superconducting coil according to the embodiment of Fig. 3.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description and drawings, identical or equivalent components, parts, and processes are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. The scale and shape of each part shown in the drawings are set for convenience to facilitate explanation, and should not be interpreted as limiting unless otherwise specified. The embodiments are merely examples and do not limit the scope of the present invention in any way. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0011] FIG. 1 is a schematic diagram showing a superconducting coil 10 according to a first embodiment. The superconducting coil 10 is configured to generate a strong magnetic field when current is applied while the superconducting coil 10 is cooled to an extremely low temperature below the superconducting transition temperature. The superconducting coil 10 may be a known superconducting coil, for example, a low-temperature superconducting coil. Alternatively, the superconducting coil 10 may be a high-temperature superconducting coil. The superconducting coil 10 is installed in high-magnetic field equipment (not shown), for example, as a magnetic field source for accelerators such as NMR systems, MRI systems, cyclotrons, high-energy physics systems such as nuclear fusion systems, or other high-magnetic field equipment, and can generate the high magnetic field required for the equipment.

[0012] 1 shows a schematic cross section of the superconducting coil 10 taken along a plane including a center line C of the superconducting coil 10. The superconducting coil 10 includes a coil body 12, a bobbin 14, and an impregnating material 16.

[0013] The coil body 12 is formed by winding the superconducting wire 18. In the illustrated example, the coil body 12 is a cylindrical coil formed by aligned multilayer winding, but is not limited to this. As another example, the coil body 12 may be a saddle-shaped coil. The coil body 12 may be formed by any other winding method and may have any other shape.

[0014] When the coil body 12 is a cylindrical coil, the bobbin 14 has a hollow cylindrical shape. The outer peripheral surface of the bobbin 14 is used as a winding surface 14a. The coil body 12 is formed by winding the superconducting wire 18 around the winding surface 14a. The bobbin 14 may also have a flange 14b. The flange 14b extends radially outward from both ends of the bobbin 14 in the direction of the center line C over the entire circumference. The flange 14b is adjacent to both ends of the coil body 12 in the direction of the center line C. The bobbin 14 may have another shape. When the coil body 12 has another winding method and / or another shape, the bobbin 14 may have a shape that is compatible with the winding method and / or shape of the coil body 12.

[0015] The reel 14 may be made of a non-magnetic metal material such as stainless steel, aluminum alloy, etc. Alternatively, the reel 14 may be made of a fiber reinforced plastic (FRP) such as glass fiber reinforced plastic (GFRP), or other non-magnetic, non-metallic material. In this example, the reel 14 may be made of an opaque material that does not transmit light.

[0016] The impregnating material 16 is impregnated into at least a portion of the coil body 12. In the illustrated example, the impregnating material 16 is filled into a recess surrounded by the winding surface 14a and flange portion 14b of the bobbin 14, the entire coil body 12 is impregnated with the impregnating material 16, and the coil body 12 is fixed to the bobbin 14.

[0017] The impregnating material 16 contains a photocurable resin material, and in this example, is made of a photocurable resin material. The photocurable resin material may be a known UV-curable resin material, such as an acrylic UV-curable resin material or an epoxy UV-curable resin material. Alternatively, the photocurable resin material may be a visible light-curable resin material.

[0018] The superconducting wire 18 includes a core 18a including a superconductor and an optically transparent coating 18b that coats the core 18a. When the superconducting coil 10 is a low-temperature superconducting coil, the core 18a may include a superconductor formed of a superconducting material such as a niobium-titanium alloy (NbTi) or a niobium-tin alloy (NbSn). When the superconducting coil 10 is a high-temperature superconducting coil, the core 18a may include a superconductor formed of, for example, magnesium diboride, a bismuth-based superconductor, a copper oxide superconductor, or another high-temperature superconducting material.

[0019] The light-transmitting coating 18b is formed of a material that transmits at least a portion of the light when irradiated with light that cures the photocurable resin material. When the impregnating material 16 is an ultraviolet-curable resin material, the light-transmitting coating 18b is transparent to ultraviolet light having a wavelength that cures the ultraviolet-curable resin material. When the impregnating material 16 is a visible-light-curable resin material, the light-transmitting coating 18b is transparent to visible light having a wavelength that cures the visible-light-curable resin material. The transmittance of the light-transmitting coating 18b for the light that cures the photocurable resin material is adjusted so that the light transmits in an amount sufficient to cure the photocurable resin material impregnated in the coil body 12. In addition to the above-mentioned light transparency, the light-transmitting coating 18b also has insulating properties to insulate adjacent superconducting wires 18 in the wound coil body 12.

[0020] As an example, the light-transmitting coating 18b may comprise a glass braid, i.e., a braided body of glass fibers. Generally, glass braids are transparent to ultraviolet and visible light. As another example, the light-transmitting coating 18b may comprise a braided body of synthetic fibers, such as polyester. Alternatively, the light-transmitting coating 18b may comprise a thin layer of a synthetic resin material, such as polyimide.

[0021] To increase the light transmittance of the superconducting wire 18, the thickness of the light-transmitting coating 18b may be at least 1% of the diameter of the superconducting wire 18. From the practical viewpoint of the superconducting coil 10, namely, to avoid an excessive decrease in the area occupied by the core material 18a in the cross section of the superconducting wire 18, the thickness of the light-transmitting coating 18b may be within 20% of the diameter of the superconducting wire 18. For example, when the superconducting wire 18 has a diameter of 1 mm, the thickness of the light-transmitting coating 18b may be 0.01 mm or more and 0.2 mm or less.

[0022] FIG. 2(a) is a diagram schematically showing the hardening process of the impregnating material 116 in the superconducting coil 110 according to the comparative example, and FIG. 2(b) is a diagram schematically showing the hardening process of the impregnating material 16 in the superconducting coil 10 according to the embodiment.

[0023] The superconducting coil 110 according to the comparative example includes a coil body 112 made of superconducting wire 118, a bobbin 114, and an impregnating material 116 containing a photocurable resin material. Not only the core material but also the insulating coating of the superconducting wire 118 is made of an opaque material that does not transmit light 22 that cures the photocurable resin material.

[0024] In the manufacturing process of the superconducting coil 110, a superconducting wire 118 is wound around the outer peripheral surface of a bobbin 114, and a coil body 112 is formed around the bobbin 114. An impregnating material 116 is filled into or applied to the coil body 112, and the coil body 112 is impregnated with the impregnating material 116. Then, in the curing process, light 22 that cures the photocurable resin material of the impregnating material 116 is irradiated from a light source 20. The light source 20 irradiates the light 22 onto the outer peripheral surface of the coil body 112 from outside the bobbin 114.

[0025] The impregnating material 116 on the outer peripheral surface of the coil body 112, which is directly hit by the light 22 from the light source 20, is hardened by the light 22. However, because the superconducting wire 118 is opaque to the light 22, the light 22 from the light source 20 is difficult to reach the impregnating material 116 in the portion of the coil body 112 that is hidden by the superconducting wire 118, as can be seen from FIG. 2( a ), due to the superconducting wire 118 acting as an obstacle. For example, the light 22 from the light source 20 is most difficult to reach the winding surface 114 a of the bobbin 114 around which the coil body 112 is wound and the impregnating material 116 in the vicinity thereof, because the superconducting wire 118 blocks the light. Therefore, the impregnating material 116 in such a portion of the coil body 112 may not be sufficiently hardened.

[0026] In contrast, in the superconducting coil 10 according to the embodiment, the light-transmitting coating 18b of the superconducting wire 18 is formed of a material that transmits at least a portion of the light 22 that cures the photocurable resin material of the impregnating material 16. Therefore, as can be seen from FIG. 2B , when light 22 is irradiated from the light source 20 during the curing process, the light-transmitting coating 18b serves as a transmission path for the light 22, allowing the light 22 to reach the impregnating material 16. The light 22 from the light source 20 can reach not only the incident surface of the coil body 12, such as the outer circumferential surface of the coil body 12, and its surrounding areas, but also inner areas of the coil body 12 that are distant from the incident surface, such as the winding surface 14a of the bobbin 14 around which the coil body 12 is wound, and the impregnating material 16 in its vicinity, through the light-transmitting coating 18b. Therefore, according to the embodiment, the impregnating material 16 can be cured more widely or entirely than in the comparative example.

[0027] If the coil body 12 is wound in multiple layers, the impregnating material 16 may be applied to each layer, and the entire coil body 12 may be impregnated with the impregnating material 16. The light 22 may be irradiated each time a layer is wound, and the impregnating material 16 impregnated in that layer may be hardened. The coil body 12 may be manufactured by repeating this process of winding, irradiating, and hardening each layer. Alternatively, the light 22 may be irradiated after all layers have been wound, and the impregnating material 16 may be hardened all at once.

[0028] As mentioned at the beginning of this book, existing superconducting coils generally use thermosetting resins as impregnation materials. The thermosetting process can take, for example, several hours to several tens of hours or longer, making the manufacture of superconducting coils long. In particular, in the impregnation method, also known as "paint winding," in which the resin material is applied while the superconducting wire is being wound around a bobbin, a thermosetting resin with a relatively long curing time is sometimes intentionally used to prevent the thermosetting resin material from interfering with the winding of the superconducting wire around the bobbin. In this case, the thermosetting process takes even longer.

[0029] In contrast, in the superconducting coil 10 according to the embodiment, a photocurable resin material is used as the impregnating material 16. The photocurable resin material typically requires a photocuring process of only a few minutes at most. Therefore, the manufacturing time of the superconducting coil 10 according to the embodiment can be dramatically reduced compared to that of existing superconducting coils.

[0030] Moreover, it is easy to selectively apply the light 22 to a local region of the coil body 12. It is also easy to apply the light 22 at any timing while the superconducting wire 18 is being wound around the bobbin 14. In contrast, the thermal curing process has a small degree of freedom in this regard.

[0031] The photocuring process offers a high degree of freedom in determining the irradiation location and timing, making it suitable for manufacturing coils with more complex shapes, such as saddle-shaped coils. Unlike circular coils, complex-shaped coils can present manufacturing challenges, such as the tension acting on the wire during the process of winding the wire around the bobbin causing the wire to shift, making it difficult to maintain the desired coil shape. However, according to the embodiment, by hardening the impregnating material at a specific location at a desired timing during the wire winding process, the wire can be temporarily fixed in place during the winding, allowing the wire to be wound while maintaining the desired coil shape. Therefore, the superconducting coil 10 according to the embodiment is advantageous for winding coils with complex shapes.

[0032] In one embodiment, the portion of the superconducting wire 18 that is pulled out from the coil body 12 (for example, the pull-out wiring 18c that extends from the coil body 12 to the electrode of the superconducting coil 10 for connecting the superconducting coil 10 to a power source) may be fixed to the reel 14 with a photocurable resin material.

[0033] Fig. 3 is a diagram schematically showing a superconducting coil 10 according to another embodiment. Fig. 4 is a diagram schematically showing a hardening process of the impregnating material 16 in the superconducting coil 10 according to another embodiment.

[0034] Similar to the above-described embodiment, the superconducting coil 10 includes a coil body 12 of superconducting wire 18, a bobbin 14 supporting the coil body 12, and an impregnating material 16 containing a photocurable resin material. The superconducting wire 18 includes a core material 18a including a superconductor and a light-transmitting coating 18b covering the core material 18a. The light-transmitting coating 18b is formed of a material that transmits at least a portion of light 22 when irradiated with light 22 that cures the photocurable resin material of the impregnating material 16.

[0035] At least a portion of the reel 14 is formed from a light-transmitting material that transmits at least a portion of the light 22 when irradiated with the light 22 that cures the photocurable resin material of the impregnation material 16. In this example, the entire reel 14 is formed from the light-transmitting material. The reel 14 may be formed from the same material as the light-transmitting coating 18b, or from a different material. The reel 14 may be formed from, for example, glass fiber reinforced plastic (GFRP). Alternatively, the reel 14 may be formed from another fiber-reinforced plastic such as carbon fiber reinforced plastic (CFRP), or a synthetic resin material such as polyimide.

[0036] In the manufacturing process of the superconducting coil 10, the superconducting wire 18 is wound around the winding surface 14a of the bobbin 14, and the coil body 12 is formed around the bobbin 14. The impregnating material 16 is filled or applied to the coil body 12, and the coil body 12 is impregnated with the impregnating material 16. Then, as shown in FIG. 4 , in the curing process, light 22 is irradiated from a light source 20 to cure the photocurable resin material of the impregnating material 16. The light source 20 irradiates the inner peripheral surface of the bobbin 14 from inside the bobbin 14 with light 22. Because the bobbin 14 is made of a light-transmitting material, the light 22 passes through the bobbin 14 and can reach the winding surface 14a and the impregnating material 16 nearby. Furthermore, the light 22 can reach the outer peripheral surface of the coil body 12 and the impregnating material 16 nearby, using the light-transmitting coating 18b of the superconducting wire 18 as a transmission path for the light 22. In this way, the impregnating material 16 can be hardened by the light 22 .

[0037] Alternatively, the light source 20 may be positioned above or below the coil body 12 and irradiate the flange 14b of the bobbin 14 with light 22. In this case, the light 22 can pass through the flange 14b and reach the impregnating material 16. In this way, the impregnating material 16 may be cured by the light 22. Furthermore, as shown in Figures 2(a) and 2(b), the light source 20 may be positioned outside the bobbin 14 and irradiate the light 22 onto the outer circumferential surface of the coil body 12, thereby curing the impregnating material 16.

[0038] 3, the superconducting wire 18 may be provided with an opaque coating made of an opaque material that does not transmit the light 22 that cures the photocurable resin material, instead of the light-transmitting coating 18b. The opaque coating of the superconducting wire 18 may be, for example, a polyvinyl fluoride (PVF) coating or an enamel coating.

[0039] Fig. 5 is a diagram schematically illustrating a modification of the superconducting coil 10 according to the embodiment of Fig. 3. As illustrated, a portion of the bobbin 14 may be formed of a light-transmitting material that transmits at least a portion of the light 22 when the light 22 that cures the photocurable resin material of the impregnation material 16 is irradiated. For example, the bobbin 14 may include a light-transmitting portion 14c adjacent to the coil body 12 and formed of a light-transmitting material.

[0040] The light-transmitting portion 14c is formed on the outer peripheral surface of the spool 14 and is interposed between the coil body 12 and the spool 14. Therefore, the winding surface 14a of the spool 14 corresponds to the outer peripheral surface of the light-transmitting portion 14c. The light-transmitting portion 14c may be a sheet of a light-transmitting material, and the thickness thereof may be at least 0.1 mm, for example. The thickness of the light-transmitting portion 14c may be within 10 mm, or within 1 mm, for example. The light-transmitting material may be a synthetic resin material such as polyimide.

[0041] When light 22 is irradiated, the light-transmitting portion 14c can be used as a transmission path for the light 22. The light 22 can reach the winding surface 14a and the impregnating material 16 in the vicinity thereof while being reflected at the interface between the light-transmitting portion 14c and the main body of the reel 14. In this way, the impregnating material 16 can be hardened by the light 22.

[0042] The present invention has been described above based on examples. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that various design changes and modifications are possible, and that such modifications are also within the scope of the present invention. Various features described in relation to one embodiment can also be applied to other embodiments. A new embodiment created by combining embodiments will have the combined effects of the respective combined embodiments.

[0043] In the above-described embodiment, the impregnating material 16 is made of a photocurable resin material, but the impregnating material 16 may contain other materials in addition to the photocurable resin material. For example, the impregnating material 16 may be a mixture of a photocurable resin material and another synthetic resin material, such as a thermosetting resin material or a thermoplastic resin material. In this case, the impregnating material 16 may be cured by both irradiating the coil body 12 with light 22 from the light source 20 and heating the coil body 12.

[0044] In the above embodiment, the case where the photocurable resin impregnating material 16 is impregnated into the entire coil body 12 has been described as an example, but the photocurable resin may be impregnated into only a portion of the coil body 12. In other words, the photocurable resin impregnating material 16 may be applied locally to the coil body 12. Another portion (e.g., the remaining portion) of the coil body 12 may be impregnated with a thermosetting resin or thermoplastic resin impregnating material.

[0045] The present invention has been described using specific terms based on the embodiments, but the embodiments merely illustrate one aspect of the principles and applications of the present invention, and many modifications and changes in arrangement are permitted to the embodiments as long as they do not deviate from the concept of the present invention as defined in the claims.

[0046] The present invention can be used in the field of superconducting coils.

[0047] 10 Superconducting coil, 12 Coil body, 14 Spool, 16 Impregnated material, 18 Superconducting wire material, 18a Core material, 18b Light-transmitting coating, 22 Light.

Claims

1. A superconducting coil comprising: a coil body formed by winding a superconducting wire; and an impregnating material containing a photocurable resin material and impregnating at least a part of the coil body, wherein the superconducting wire includes a light-transmissive coating that transmits at least a part of the light when the light for curing the photocurable resin material is irradiated.

2. The superconducting coil according to claim 1, wherein the light-transmissive coating includes a braided body.

3. The superconducting coil according to claim 1, wherein the impregnating material is made of the photocurable resin material.

4. The superconducting coil according to any one of claims 1 to 3, further comprising a winding frame around which the superconducting wire is wound, and at least a part of the winding frame is formed of a light-transmissive material that transmits at least a part of the light when the light for curing the photocurable resin material is irradiated.

5. The superconducting coil according to claim 4, wherein at least a part of the winding frame is formed of the light-transmissive material so that the light transmits from the inner peripheral surface to the outer peripheral surface of the winding frame.

6. The superconducting coil according to claim 4, wherein the winding frame is formed of the light-transmissive material on the outer peripheral surface of the winding frame and includes a light-transmissive portion interposed between the coil body and the winding frame.

7. The superconducting coil according to claim 4, wherein the light-transmissive material includes a glass fiber reinforced plastic.

8. The superconducting coil according to any one of claims 1 to 3, further comprising a winding frame around which the superconducting wire is wound, and a portion of the superconducting wire drawn out from the coil body is fixed to the winding frame with a photocurable resin material.

9. A superconducting coil comprising: a coil body formed by winding a superconducting wire; an impregnating material containing a photocurable resin material and impregnating at least a part of the coil body; and a winding frame around which the superconducting wire is wound, and at least a part of the winding frame is formed of a light-transmissive material that transmits at least a part of the light when the light for curing the photocurable resin material is irradiated.

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