Magnetic field generating coil and method for manufacturing the same

Abstract

To provide a magnetic field generating coil that reliably prevents insulation failure between adjacent turns of tape-shaped wire. [Solution] The magnetic field generating coil 10 has a first tape-shaped wire 11 with a first insulating layer 31 on one side and a first conductive layer 21 on the other side, and a second tape-shaped wire 12 with a second insulating layer 32 on one side and a second conductive layer 22 on the other side, and is formed by winding the first tape-shaped wire 11 and the second tape-shaped wire 12 together with the first insulating layer 31 and the second insulating layer 32 together.

Description

Technical Field

[0001] Embodiments of the present invention relate to a magnetic field generating coil configured with a tape-shaped wire material.

Background Art

[0002] In recent years, research on magnetic field generating coils using high-temperature superconducting wire materials has been actively conducted. As this high-temperature superconducting wire material, a REBCO wire material composed of (RE)Ba₂Cu₃O₇ containing rare earth (RE) is widely known. The tape-shaped high-temperature superconducting wire material wound together with an insulating layer having a thickness of about 50 to 100 μm has a characteristic of large current capacity under a high magnetic field.

[0003] By bringing out the characteristics of high-temperature superconducting wire materials such as higher current density and higher allowable stress, realization of a magnetic field generating coil that generates a high magnetic field is expected. Most of the currently commercially available high-temperature superconducting wire materials are generally bare conductors without an insulating layer provided around the copper stabilization layer. When manufacturing a magnetic field generating coil by winding such a bare conductor high-temperature superconducting wire material, insulation between coil turns is essential.

[0004] As described above, for insulation between turns of a magnetic field generating coil, a method is known in which an insulating tape formed by making an insulating material into a tape shape is overlapped and wound around a high-temperature superconducting wire material. As the material of such an insulating tape, plastics such as polyimide and fluororesin are used.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of Invention

Problems to be Solved by Invention

[0006] When insulating tape is wound over high-temperature superconducting wire, the relative positions of the insulating tape and the high-temperature superconducting wire in the tape width direction may shift. This could lead to direct contact between adjacent turns of high-temperature superconducting wire, potentially causing insulation failure.

[0007] In particular, insulating tapes made of plastics such as polyimide and fluororesin are softer and more easily deformed than metal high-temperature superconducting wires. When unintended external forces are applied to the insulating tape, deformation such as bending, folding, and twisting can occur, causing it to become entangled in the superconducting coil. This reduces the effective cross-sectional area of ​​the insulating tape, potentially leading to direct contact between adjacent high-temperature superconducting wires and resulting in insulation failure.

[0008] To reduce the probability of such insulation failures, one possible solution is to simply increase the thickness of the insulating tape. However, when such a measure is taken, the spacing between the high-temperature superconducting wires located on either side of the insulating tape widens as the thickness increases. While this reduces the probability of insulation failures between adjacent high-temperature superconducting wires, it presents the problem of a decrease in the packing factor of the superconducting wires and a resulting decrease in current density.

[0009] Furthermore, to prevent insulation failures between adjacent turns, one possible measure is to cover the entire circumference of the high-temperature superconducting wire with an insulating layer. While this would prevent insulation failures with a very high probability, challenges remain in terms of cooling the high-temperature superconducting wire. Specifically, applying an insulating layer to the surface of the high-temperature superconducting wire increases the thermal resistance between the high-temperature superconducting wire and the surrounding heat transfer medium, reducing the cooling efficiency of the high-temperature superconducting wire.

[0010] Another possible measure to prevent insulation failure between adjacent turns is to cover the entire circumference of the metal reinforcing wire wound together with the high-temperature superconducting wire with an insulating layer. However, even in this case, the thermal resistance between the reinforcing wire and the surrounding heat transfer medium increases, reducing the cooling efficiency of the high-temperature superconducting wire.

[0011] Therefore, measures are being considered to provide an insulating layer only on the tape surface of the reinforcing wire or high-temperature superconducting wire. By limiting the area of ​​the insulating layer to the tape surface rather than the entire circumference of the reinforcing wire in this way, the thermal resistance between the reinforcing wire and the surrounding heat transfer medium can be minimized.

[0012] However, in this case, if the reinforcing wire or high-temperature superconducting wire is wound with a misalignment in the tape width direction, the side ends of the reinforcing wire or high-temperature superconducting wire, which do not have an insulating layer, come into contact with the tape surface of the high-temperature superconducting wire in the adjacent turn, causing insulation failure.

[0013] Embodiments of the present invention have been made in consideration of these circumstances, and aim to provide a magnetic field generating coil that reliably prevents insulation failure between adjacent turns of a tape-shaped wire. [Means for solving the problem]

[0014] The magnetic field generating coil according to the embodiment comprises a first tape-shaped wire having a first insulating layer on one side and a first conductive layer on the other side, and a second tape-shaped wire having a second insulating layer on one side and a second conductive layer on the other side, characterized in that the first tape-shaped wire and the second tape-shaped wire are wound around each other with the first and second insulating layers together. [Effects of the Invention]

[0015] Embodiments of the present invention provide a magnetic field generating coil that reliably prevents insulation failure between adjacent turns of a tape-shaped wire. [Brief explanation of the drawing]

[0016] [Figure 1] An explanatory diagram of the manufacturing method for a magnetic field generating coil according to the first embodiment. [Figure 2] An enlarged radial cross-sectional view of the magnetic field generating coil according to the first embodiment. [Figure 3] An explanatory diagram of the manufacturing method for a magnetic field generating coil according to the second embodiment. [Figure 4] An enlarged radial cross-sectional view of the magnetic field generating coil according to the second embodiment. [Figure 5] A perspective view showing a radial cross-section of the magnetic field generating coil according to the third embodiment. [Figure 6] (A)(B)(C)(D) Enlarged cross-sectional views of the magnetic field generating coil according to the third embodiment. [Figure 7] An explanatory diagram of the method for manufacturing the magnetic field generating coil according to the fourth embodiment. [Mode for Carrying Out the Invention]

[0017] (First Embodiment) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of the manufacturing method of the magnetic field generating coil 10A (10) according to the first embodiment. This FIG. 1 shows the X-Y plane of a coordinate system in which the rotation axis of the winding drum 15 of the magnetic field generating coil 10A is set to the Z axis. FIGS. 2(A), (B), and (C) are enlarged radial cross-sectional views (Z-X cross-sectional views) of the magnetic field generating coil 10A (10).

[0018] The steps of the method for manufacturing the magnetic field generating coil 10A include a step of feeding out the first tape-shaped wire 11 having the first insulating layer 31 on one side and the first conductive layer 21 on the opposite side, a step of feeding out the second tape-shaped wire 12 having the second insulating layer 32 on one side and the second conductive layer 22 on the opposite side, and a step of winding the first tape-shaped wire 11 and the second tape-shaped wire 12 in a state where the first insulating layer 31 and the second insulating layer 32 are brought into contact with each other.

[0019] As shown in the embodiment, the structure of the magnetic field generating coil 10, in which a plurality of wires 11 and 12 having conductive layers 21 and 22 are bundled and wound around the winding drum 15, the respective conductive layers 21 and 22 are combined to form the n-th turn (n=1 to N) through which current circulates, is referred to as a bundle structure. The magnetic field generating coil 10A has a bundle number of 2 formed by combining two wires (the first conductive layer 21 and the second conductive layer 22), and is wound up to the n-th turn (n=1 to N).

[0020] The first conductive layer 21 and the second conductive layer 22 can utilize either normal conductivity or superconductivity. In the conductive layers 21 and 22 that utilize superconductivity, although not shown in the figures, they are generally formed into a tape shape by laminating multiple thin film layers. Such conductive layers 21 and 22 are, for example, REBCO wires made of (RE)Ba2Cu3O7 containing rare earth elements (RE).

[0021] The first insulating layer 31 and the second insulating layer 32 are integrally formed with the first conductive layer 21 and the second conductive layer 22, respectively. Preferably, the tape width of the first insulating layer 31 and the second insulating layer 32 is about the same as the tape width of the first conductive layer 21 and the second conductive layer 22.

[0022] Furthermore, the materials constituting the first insulating layer 31 and the second insulating layer 32 can be any insulating material, such as polyvinyl formal, polyvinyl butyral, polyester, polyurethane, polyamide, polyamide-imide, polyimide, epoxy, acrylic, fluororesin, or metal oxide. The thickness of these insulating layers 31 and 32 can be, for example, 1 to 10 μm.

[0023] As shown in the enlarged cross-sectional view of ZX in Figure 2, the inner circumference of the magnetic field generating coil 10A can be in two states: (A) when the first insulating layer 31 is in contact with the winding drum 15, and (B) when the second conductive layer 22 is in contact with the winding drum 15. Similarly, the outer circumference of the magnetic field generating coil 10A can be in two states: (A) when the second insulating layer 32 is exposed, and (B) when the first conductive layer 21 is exposed. In total, there are four possible combinations, but in all cases, the combination of the first tape-shaped wire 11 and the second tape-shaped wire 12 is defined as the nth turn (n=1 to N). The boundary of each nth turn (n=1 to N) is insulated from the adjacent (n-1)th and (n+1)th turns by the two first insulating layers 31 and the second insulating layer 32.

[0024] In Figure 1, the first tape-shaped wire 11 and the second tape-shaped wire 12 are pre-wound onto the first reel 16 and the second reel 17, respectively. Although the first conductive layer 21 and the second conductive layer 22 are shown facing inward, they may also be wound onto the first reel 16 and the second reel 17 with the first insulating layer 31 and the second insulating layer 32 facing inward. Furthermore, the manufacturing method shown in Figure 1 is merely an example illustrating the concept and does not limit the process of winding the first tape-shaped wire 11 and the second tape-shaped wire 12.

[0025] Furthermore, although the first tape-shaped wire 11 and the second tape-shaped wire 12 are shown as identical examples in Figures 1 and 2, they may be different. In other words, the first conductive layer 21 and the second conductive layer 22, or the first insulating layer 31 and the second insulating layer 32, may be combined with the same specifications or with different specifications, depending on their respective specifications.

[0026] Furthermore, while a circular pancake shape was given as an example for the shape of the magnetic field generating coil 10, it is not limited to this and can also be applied to non-circular shapes such as saddle-shaped or elliptical shapes. Also, the radially enlarged ZX cross-section shown in Figure 2 is just one example and does not limit the configuration of the magnetic field generating coil 10A.

[0027] The first tape-shaped wire 11, a component of the magnetic field generating coil 10A, is pre-fabricated with a first insulating layer 31 on one side and a first conductive layer 21 on the other. Similarly, the second tape-shaped wire 12, also a component, is pre-fabricated with a second insulating layer 32 on one side and a second conductive layer 22 on the other. The magnetic field generating coil 10A is constructed by winding the first tape-shaped wire 11 and the second tape-shaped wire 12 together with the first insulating layer 31 and the second insulating layer 32 attached.

[0028] In this way, the first insulating layer 31 and the second insulating layer 32 are wound together, resulting in twice the thickness of each individual layer, which contributes to improving the insulation of each of the nth turns (n=1 to N). The first conductive layer 21 and the second conductive layer 22 are also wound together to form each of the nth turns (n=1 to N). As a result, each of the nth turns (n=1 to N) has twice the thickness of the individual conductive layers 21 and 22, which contributes to improving the current capacity.

[0029] Next, we will describe the mechanism for avoiding insulation failure in the magnetic field generating coil 10 of this embodiment. In the magnetic field generating coil 10, as shown in Figures 2(A) and 2(B), it is ideal for adjacent first tape-shaped wires 11 and second tape-shaped wires 12 to be wound with their ends aligned in the vertical direction shown. However, in reality, as shown in Figure 2(C), adjacent first tape-shaped wires 11 and second tape-shaped wires 12 may be wound with their ends offset in the direction of the rotation axis Z. Alternatively, although not shown in the illustration, the first tape-shaped wires 11 and second tape-shaped wires 12 may be wound in a state where they are not parallel to each other.

[0030] According to this embodiment, even if the first tape-shaped wire 11 and the second tape-shaped wire 12 are wound in a misaligned state, the first insulating layer 31 and the second insulating layer 32 located on both sides of the nth turn (n=1 to N) of each will not be misaligned with respect to the corresponding first conductive layer 21 and the second conductive layer 22. Therefore, even if the first tape-shaped wire 11 and the second tape-shaped wire 12 are compressed in the radial direction of the coil by the winding tension and are misaligned, short circuits of the conductive layers 21 and 22 are unlikely to occur between the adjacent n+1th turn, nth turn, and n-1st turn. In other words, when the first tape-shaped wire 11 and the second tape-shaped wire 12 are wound together, the first insulating layer 31 and the second insulating layer 32 are in contact with each other. Therefore, even if either the first tape-shaped wire 11 or the second tape-shaped wire 12 is in contact at an oblique angle, it is unlikely that the first conductive layer 21 and the second conductive layer 22 will be short-circuited.

[0031] Because insulation failure is avoided by this mechanism, insulation can be maintained even with thin first insulating layer 31 and second insulating layer 32. As a result, the packing factor of the first conductive layer 21 and second conductive layer 22 in the magnetic field generating coil 10 can be improved, and the current density can be increased.

[0032] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to Figure 3. Figure 3 is an explanatory diagram of the manufacturing method of the magnetic field generating coil 10B(10) according to the second embodiment. Figure 4 is an enlarged radial cross-sectional view of the magnetic field generating coil 10B(10). In Figures 3 and 4, parts having the same configuration or function as those in Figures 1 and 2 are indicated by the same reference numerals, and redundant explanations are omitted.

[0033] As shown in Figure 3, the manufacturing method for the magnetic field generating coil 10B of the second embodiment further includes a step of feeding out the third tape-shaped wire 13, which is pre-wound on the third reel 18, so that it is sandwiched between the first tape-shaped wire 11 and the second tape-shaped wire 12, in addition to the manufacturing method of the first embodiment. Note that the manufacturing method shown in Figure 3 is a conceptual example and does not limit the winding process of the third tape-shaped wire 13.

[0034] As shown in Figure 4, the magnetic field generating coil 10B of the second embodiment has a configuration in which a third tape-shaped wire 13 is further added between the first conductive layer 21 of the first tape-shaped wire 11 and the second conductive layer 22 of the second tape-shaped wire 12, as in the configuration of the first embodiment described above.

[0035] In the magnetic field generating coil 10B(10) shown in Figure 4, the third tape-shaped wire 13 is made of the same material as the first conductive layer 21 or the second conductive layer 22, but the two may be conductive layers with different specifications. Furthermore, the third tape-shaped wire 13 is not limited to being a solid conductive layer, but may also include a composite material of a conductive layer and an insulating layer, or a reinforcing wire 26, which will be described later.

[0036] The magnetic field generating coil 10B is made by combining three wires (first conductive layer 21, third tape-shaped wire 13, and second conductive layer 22) to form a bundle of 3, with n turns (n=1 to N) wound around it.

[0037] In the magnetic field generating coil 10B, the first insulating layer 31 and the second insulating layer 32 are wound together, resulting in twice the thickness of each individual layer, contributing to improved insulation for each of the nth turns (n=1 to N). When the third tape-shaped wire 13 is the same as the first conductive layer 21, the first conductive layer 21, the third tape-shaped wire 13, and the second conductive layer 22 are also combined to form each of the nth turns (n=1 to N). As a result, each of the nth turns (n=1 to N) has three times the thickness of the insulating layers 31 and 32 individually, contributing to improved current capacity.

[0038] In the second embodiment, the case where the number of bundles is 3 was illustrated, but any number of bundles m can be achieved by adding a third tape-shaped wire 13 and an additional m-th tape-shaped wire (4≦m) between the first tape-shaped wire 11 and the second tape-shaped wire 12.

[0039] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to Figures 5 and 6. Figure 5 is a perspective view showing a radial cross-section of the magnetic field generating coil 10C(10) according to the third embodiment. Figures 6(A), (B), (C), and (D) are enlarged cross-sectional views of the magnetic field generating coils 10C(10C1, 10C2, 10C3, 10C4) according to the third embodiment. In Figures 5 and 6, parts having the same configuration or function as those in Figures 1 and 2 are indicated by the same reference numerals, and redundant explanations are omitted.

[0040] The magnetic field generating coil 10C of the third embodiment has a configuration in which an adhesive layer 25 is interposed between the contact surfaces of the first tape-shaped wire 11 and the second tape-shaped wire 12, as described above in the configuration of the first embodiment. By winding the coil with the adhesive layer 25 interposed in this way, the first tape-shaped wire 11 and the second tape-shaped wire 12 are fixed together, improving the thermal conductivity and mechanical strength of the magnetic field generating coil 10C. Note that the interposed adhesive layer 25 has voids in some places on the contact surface and therefore does not electrically insulate the first conductive layer 21 and the second conductive layer 22.

[0041] Furthermore, an insulating sheet 27 is provided on the side surface of the magnetic field generating coil 10C to insulate it from other magnetic field generating coils (not shown) that are stacked in the winding axis Z direction. Epoxy resin or fiber-reinforced plastic is preferably used for this insulating sheet 27. The adhesive layer 25 is also filled not only on the contact surface of the tape-shaped wires 11 and 12 but also between the insulating sheets 27.

[0042] The first tape-shaped wire 11 and the second tape-shaped wire 12 shown in Figures 6(A), (B), and (D) are identical, but the first tape-shaped wire 11 and the second tape-shaped wire 12 shown in Figure 6(C) are different. Also, the third tape-shaped wire 13 shown in Figure 6(B) is made of the same material as the first conductive layer 21 or the second conductive layer 22, but the third tape-shaped wire 13 shown in Figure 6(D) is made of a different material than the first conductive layer 21 or the second conductive layer 22.

[0043] (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to Figure 7. Figure 7 is an explanatory diagram of the manufacturing method of the magnetic field generating coil 10D(10) according to the fourth embodiment. In Figure 7, parts that have the same configuration or function as those in Figure 1 are indicated by the same reference numerals, and redundant explanations are omitted.

[0044] The magnetic field generating coil 10D of the fourth embodiment has a configuration in which a metal reinforcing wire 26 is provided on one side of the first conductive layer 21 and the second conductive layer 22 of the first or second embodiment described above. Alternatively, it is conceivable that the second conductive layer 22 in the first and second embodiments may be replaced entirely with the reinforcing wire 26.

[0045] Examples of reinforcing wires 26 include high-strength metal materials such as nickel-based alloys, stainless steel, or copper, but are not limited to these; any material with a higher Young's modulus than the conductive layers 21 and 22 is preferably used. The purpose of winding the reinforcing wires 26 together with the conductive layers 21 and 22 is to integrate them to improve rigidity and reinforce mechanical strength. Furthermore, the reinforcing wires 26 also have the effect of reducing circumferential strain when circumferential tensile stress (hoop stress) is applied to the magnetic field generating coil 10 by electromagnetic force. In addition, the effects of the first to third embodiments are carried over to the magnetic field generating coil 10D of the fourth embodiment.

[0046] According to the magnetic field generating coil 10 of at least one embodiment described above, by winding the first tape-shaped wire 11 and the second tape-shaped wire 12 with the first insulating layer 31 and the second insulating layer 32 together, it is possible to reliably prevent insulation failure between adjacent turns of the tape-shaped wire.

[0047] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, modifications, and combinations are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0048] 10 (10A, 10B, 10C, 10D)... Magnetic field generating coil, 11... First tape-shaped wire, 12... Second tape-shaped wire, 13... Third tape-shaped wire, 15... Winding drum, 16... First reel, 17... Second reel, 18... Third reel, 21... First conductive layer, 22... Second conductive layer, 25... Adhesive layer, 26... Reinforcement wire, 27... Insulating sheet, 31... First insulating layer, 32... Second insulating layer.

Claims

1. A first tape-shaped wire having a first insulating layer on one side and a first conductive layer on the other, A second tape-shaped wire having a second insulating layer on one side and a second conductive layer on the other, It has, A magnetic field generating coil formed by winding the first tape-shaped wire and the second tape-shaped wire with the first insulating layer and the second insulating layer together.

2. In the magnetic field generating coil according to claim 1, A magnetic field generating coil in which a third tape-shaped wire is provided between the first conductive layer of the first tape-shaped wire and the second conductive layer of the second tape-shaped wire.

3. In the magnetic field generating coil according to claim 2, The third tape-shaped wire is a magnetic field generating coil made of the same material as the first conductive layer or the second conductive layer.

4. In a magnetic field generating coil according to any one of claims 1 to 3, A magnetic field generating coil in which the first tape-shaped wire and the second tape-shaped wire are the same.

5. In a magnetic field generating coil according to any one of claims 1 to 3, A magnetic field generating coil in which an adhesive layer is interposed between the contact surfaces of the first tape-shaped wire and the second tape-shaped wire.

6. In a magnetic field generating coil according to any one of claims 1 to 3, A magnetic field generating coil having a metal reinforcing wire provided on one side of the first conductive layer and the second conductive layer.

7. In a magnetic field generating coil according to any one of claims 1 to 3, The second tape-shaped wire is a magnetic field generating coil in which the second conductive layer is replaced with a metal reinforcing wire.

8. A process of supplying a first tape-shaped wire having a first insulating layer on one side and a first conductive layer on the other side, A process of supplying a second tape-shaped wire, in which one side is the second insulating layer and the other side is the second conductive layer, A method for manufacturing a magnetic field generating coil, comprising the step of winding the first tape-shaped wire and the second tape-shaped wire while the first insulating layer and the second insulating layer are combined.

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