Stacked high-temperature superconducting coil device

Abstract

To provide a stacked high temperature superconducting coil device that suppresses deformation of a superconducting coil due to compressive stress in the axial direction even when high electromagnetic force is generated due to a strong magnetic field.SOLUTION: A high temperature superconducting coil device according to an embodiment includes pancake coils with multiple layers stacked in the axial direction, each of which includes a pancake-shaped superconducting coil made by concentrically winding high-temperature superconducting tape wire around an insulating winding frame, and a reinforcing wire wound around the outermost circumference of the superconducting coil, and an axial reinforcing member disposed on the outer circumferential surface of the reinforcing wire in the radial direction, and the reinforcing wires adjacent in the axial direction connect at least parts of their respective outer circumferential surfaces via the axial reinforcing member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a stacked-type high-temperature superconducting coil device in which a plurality of high-temperature superconducting coils, each of which is formed by winding a high-temperature superconducting wire around a bobbin, are stacked. [Background technology]

[0002] A stacked-type high-temperature superconducting coil device, in which multiple superconducting coils, each made by winding high-temperature superconducting wire around a bobbin, are stacked in the central axis direction, is subjected to electromagnetic forces due to the self-magnetic field when current is applied and external magnetic fields. These electromagnetic forces generate hoop stress, which is electromagnetic stress in the direction that expands the superconducting coil radially, and axial compressive stress, which deforms the winding portion of the superconducting coil radially and axially. If such hoop stress or axial compressive stress exceeds the allowable stress of the superconducting wire, the superconducting characteristics will deteriorate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-219196 Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, a configuration has been considered in which a retaining ring made of reinforcing wire such as metal tape is placed on the outer surface of the superconducting coil to suppress radial deformation of the superconducting coil, thereby reducing the hoop stress acting on the superconducting wire and preventing deterioration of the superconducting properties.

[0005] However, with this configuration, the width of the reinforcing wire is limited by the height of each pancake coil, so it is not possible to reduce axial compressive stress or suppress deformation. Therefore, when a strong magnetic field generates a high electromagnetic force, the axial compressive stress may degrade the superconducting characteristics. Furthermore, if the superconducting coils move even slightly due to axial deformation, the imbalance in electromagnetic force can destroy mechanically weak points, such as the connections between the superconducting coils, and in the worst case, cause them to burn out.

[0006] The problem to be solved by the present invention is to provide a stacked high-temperature superconducting coil device that suppresses deformation of the superconducting coil due to axial compressive stress, even when a high electromagnetic force is generated due to a strong magnetic field. [Means for solving the problem]

[0007] In order to solve the above problems, the stacked high-temperature superconducting coil device of the embodiment has a pancake-shaped superconducting coil formed by concentrically winding high-temperature superconducting tape wire around an insulating winding frame, and a reinforcing wire wound around the outermost periphery of the superconducting coil, and is equipped with multiple pancake coils stacked in the axial direction, and axial reinforcing members arranged on the radial outer peripheral surfaces of the reinforcing wire, and at least portions of the outer peripheral surfaces of the reinforcing wires adjacent in the axial direction are connected via the axial reinforcing members. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B show a stacked high-temperature superconducting coil device according to a first embodiment, in which (a) is a cross-sectional view thereof and (b) is an enlarged view of part A in (a). [Figure 2] 3A and 3B show a superconducting coil according to the first embodiment, in which (a) is a perspective view, (b) is a cross-sectional view, and (c) is an enlarged view of part B in (b). [Figure 3] 1 is a schematic perspective view of a superconducting tape wire according to a first embodiment. [Figure 4] FIG. 10 is a cross-sectional plan view of a stacked high-temperature superconducting coil device according to a second embodiment. [Figure 5] 10A and 10B show a stacked high-temperature superconducting coil device according to a third embodiment, in which (a) is a cross-sectional view thereof and (b) is an enlarged view of part C in (a). [Figure 6] 10A and 10B show a stacked high-temperature superconducting coil device according to a fourth embodiment, where (a) is a cross-sectional view thereof and (b) is an enlarged view of part D in (a). DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (First embodiment) The first embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 shows a stacked high-temperature superconducting coil device according to this embodiment, where (a) is a cross-sectional view and (b) is an enlarged view of part A in (a).

[0011] The stacked high-temperature superconducting coil device 10 of this embodiment includes a bobbin 20, superconducting coils 30, reinforcing wires 40, and an axial reinforcing member 50. A plurality of superconducting coils 30 are stacked in the direction of the central axis of the superconducting coils 30 (hereinafter also referred to as the axial direction), and a reinforcing wire 40 is wound around the outermost periphery of each superconducting coil 30. Furthermore, the axial reinforcing member 50 is provided on the outer periphery in the radial direction of the reinforcing wires 40 so that the outer periphery of each of the reinforcing wires 40 adjacent in the central axis direction of the superconducting coil 30 in the radial direction (hereinafter also referred to as the radial direction) of the superconducting coil 30 is connected via the reinforcing member 50 in the axial direction.

[0012] Here, when distinguishing between the stacked reinforcing members 40, they are referred to with subscripts such as reinforcing wire 40a, reinforcing wire 40b, etc. Furthermore, the outline arrows in the drawings indicate radial and axial electromagnetic forces, with the solid arrow indicating the radial direction and the dashed-dotted arrow indicating the central axis of the superconducting coil 30, respectively.

[0013] 2, superconducting coil 30 is formed by overlapping superconducting tape wire 30a and insulating tape wire 30b and spirally winding them around insulating bobbin 20 made of insulating material such as glass fiber reinforced plastic or reinforced PTFE (polytetrafluoroethylene) to form winding portion 31. Furthermore, when multiple superconducting coils 30 are stacked, insulating layers 32 are formed on the top and bottom surfaces of winding portion 31 to insulate and protect winding portion 31 from winding portions in other layers.

[0014] The superconducting coil 30 is integrally impregnated and hardened with a resin such as epoxy (not shown), which suppresses mechanical movement of the superconducting tape wire 30a and maintains its strength when the superconducting coil 30 is in use. It also provides insulation protection between the turns of the superconducting tape wire 30a and prevents quenching, which is a state in which the superconducting state of the superconducting coil 30 is destroyed.

[0015] 3, the superconducting tape wire 30a has a tape substrate 33, an intermediate layer 34, and a superconducting layer 35, both surfaces of which are covered with stabilizing layers 36. An orientation layer 37 may be provided between the tape substrate 33 and the intermediate layer 34, and a protective layer 38 may be provided between the superconducting layer 35 and the stabilizing layer 36.

[0016] The tape substrate 33 is provided for the purpose of maintaining the strength of the superconducting tape wire 30a, and is made of a material such as a high-strength metal, such as Hastelloy (registered trademark) or a Ni-based alloy such as NiW.

[0017] The intermediate layer 34 is a diffusion prevention layer and is made of a material such as cerium oxide, yttria-stabilized zirconia (YSZ), magnesium oxide, yttrium oxide, ytterbium oxide, or barium zirconia, and is formed on the tape substrate 33.

[0018] The superconducting layer 35 is made of a superconductor thin film having, for example, an RE123-based composition (RE1B2C3O7, etc.). Note that "RE" in "RE1B2C3O7" represents at least one of a rare earth element (e.g., neodymium (Nd), gadolinium (Gd), holmium (Ho), samarium (Sm), etc.) and an yttrium element, "B" represents barium (Ba), "C" represents copper (Cu), and "O" represents oxygen (O).

[0019] The stabilization layer 36 is provided for the purpose of preventing the superconducting layer 35 from burning when an excessive current flows through the superconducting layer 35, and is made of, for example, conductive silver.

[0020] The orientation layer 37 is provided for the purpose of orienting the intermediate layer 34 on the tape substrate 33, and is made of, for example, magnesium oxide (MgO), etc. Note that this can be omitted when an oriented substrate is used.

[0021] Protective layer 38 is provided for the purpose of preventing superconducting layer 35 from being deteriorated due to contact with moisture in the air, and is made of, for example, silver. Like stabilizing layer 36, protective layer 38 also plays a role in preventing superconducting layer 35 from burning when an excessive current flows through superconducting layer 35.

[0022] The superconducting tape wire 30a having such multiple layers has a tape width w of, for example, 4 to 12 mm and a thickness t of 0.1 to 0.2 mm. The superconducting tape wire 30a has excellent mechanical strength in the longitudinal direction, but is characterized by being vulnerable to tensile stress (peeling stress) in the direction perpendicular to the tape surface.

[0023] The superconducting tape wire 30a may be coated with an insulating material such as polyimide or polyimide amide to form an insulating coated superconducting tape wire.

[0024] The reinforcing wire 40 is preferably made of a high-strength metal such as a copper alloy, an aluminum alloy, stainless steel, or a nickel-based alloy.

[0025] The axial reinforcing member 50 is preferably made of a material having a Young's modulus equal to or greater than that of the reinforcing wire material 40. Furthermore, a non-magnetic material that is not magnetized by the magnetic field generated by the stacked high-temperature superconducting coil device 10 is preferable, and suitable examples include high-strength metals such as copper alloys including high-strength brasses such as CuNi, CuBe, and C6782, aluminum alloys such as Al-Mg-based A5083 and Al-Zn-Mg-based A7024 and A7003, stainless steel, and nickel-based alloys such as Inconel (registered trademark) and Hastelloy (registered trademark), and these may also be used in combination.

[0026] The axial reinforcing member 50 can be formed by fitting a ring-shaped member to the superconducting coil 30, or by winding a plate material having a width that matches the stacking height of the superconducting coil 30. Alternatively, the axial reinforcing member 50 may be formed by connecting and integrating ring-shaped members that are divided in the axial direction.

[0027] For ease of manufacturing, the axial reinforcing member 50 and the reinforcing wire 40, and the turns of the plate material when it is wound, may be non-glued, but for structural integration, they may be fixed via an adhesive layer such as a synthetic resin such as epoxy, an adhesive, or solder (not shown).

[0028] Next, the operation of the stacked high-temperature superconducting coil device 10 will be described.

[0029] In the stacked high-temperature superconducting coil device 10 of this embodiment configured as described above, the reinforcing wires 40 a and 40 b adjacent in the axial direction are connected via the axial reinforcing member 50 .

[0030] With this configuration, even if the superconducting coil 30 attempts to deform in the axial direction due to electromagnetic force, the axial reinforcing member 50 suppresses the axial deformation of the superconducting coil 30. Furthermore, even in cases where a strong electromagnetic force is generated due to a strong magnetic field, suppressing the deformation of the superconducting coil 30 reduces the axial compressive stress acting on the superconducting tape wire 30a, thereby enabling stable current flow without deteriorating the superconducting properties.

[0031] In addition, the thermal contraction rate of the axial reinforcing member 50 may be set to be greater than the thermal contraction rate of the superconducting coil 30 equipped with the reinforcing wire 40, thereby more firmly integrating the axial reinforcing member 50 and the reinforcing wire 40 due to the difference in thermal contraction.

[0032] The same effect can be expected when a double-pancake shaped superconducting coil is used for the superconducting coil 30, and a single-pancake shaped superconducting coil and a double-pancake shaped superconducting coil may be combined and stacked. The shape of the superconducting coil 30 is not limited to a circular shape, and the same effect can be obtained with a non-circular coil consisting of straight portions and arc portions, an elliptical coil, or a three-dimensional coil wound three-dimensionally, such as a saddle coil.

[0033] As described above, according to this embodiment, the reinforcing wires 40 that are provided on the outer periphery of the superconducting coil 30 and that are adjacent in the axial direction are connected to each other via the axial reinforcing member 50. With this configuration, even when a strong electromagnetic force is generated due to a strong magnetic field, it is possible to suppress the deformation of the superconducting coil 30 in the axial direction, and to enable stable current flow without deteriorating the superconducting characteristics.

[0034] (Second embodiment) The second embodiment will be described with reference to Fig. 4. The same components as those in the first embodiment are given the same reference numerals, and detailed description will be omitted. Fig. 4 is a plan cross-sectional view of a stacked high-temperature superconducting coil device according to the second embodiment. As shown in Fig. 4, in this embodiment, the axial reinforcing member 50 is divided into two in the circumferential direction of the superconducting coil 30, and the two axial reinforcing members 50a, 50b are connected at a portion of the circumferential direction by fastening bolts and nuts 51.

[0035] In this embodiment configured as described above, by fastening the bolts and nuts 51, the outer periphery of the reinforcing wire 40 can be compressed in the radial direction by the two axial reinforcing members 50a and 50b.

[0036] With this configuration, the outer periphery of the reinforcing wire 40 can be compressed in the radial direction, thereby more firmly integrating the axial reinforcing member 50 and the reinforcing wire 40. Therefore, compared to the first embodiment, the axial deformation of the superconducting coil 30 can be further suppressed, and even in cases where a strong electromagnetic force is generated by a strong magnetic field, current can be stably passed through the coil without deteriorating the superconducting characteristics.

[0037] The connection method is not limited to the bolt and nut method, but may be performed by welding or pressure welding, in which case the two axial reinforcing members 50a, 50b may be connected in a state in which the outer periphery of the reinforcing wire 40 is separately compressed. Furthermore, although the embodiment has been described with reference to an example in which the axial reinforcing member 50 is divided into two pieces in the circumferential direction, it is of course possible to divide it into three or more pieces in some cases.

[0038] (Third embodiment) The third embodiment will be described with reference to Fig. 5. The same components as those in the first and second embodiments are given the same reference numerals, and detailed descriptions will be omitted. Fig. 5 shows a stacked high-temperature superconducting coil device according to the third embodiment, with (a) being its cross-sectional view and (b) being an enlarged view of part C in (a).

[0039] In this embodiment, as shown in Figure 5, the axial reinforcing member 50 further includes an extension portion 52 extending radially inward of the superconducting coil 30 so as to axially connect at least a portion of the surfaces of the opposing axial end portions of the reinforcing wires 40c and 40d.

[0040] In the present embodiment configured as described above, the gap between the opposing axial end portions of the reinforcing wires 40c and 40d is filled with the extensions 52 of the axial reinforcing member 50.

[0041] With this configuration, the gap between the opposing axial ends of the reinforcing wires 40c and 40d is filled and connected by the extensions 52 of the axial reinforcing member 50, so that the axial deformation of the superconducting coil 30 due to electromagnetic force can be further suppressed compared to the first and second embodiments. Therefore, even when a strong electromagnetic force is generated due to a strong magnetic field, current can be stably passed through the coil without deteriorating the superconducting characteristics.

[0042] The extension 52 need only be continuously connected to the axial reinforcing member 50, and does not have to be formed by cutting; the extension 52 may be manufactured separately and then integrated.

[0043] (Fourth embodiment) The fourth embodiment will be described with reference to Fig. 6. The same components as those in the first to third embodiments are given the same reference numerals, and detailed descriptions will be omitted. Fig. 6 shows a stacked high-temperature superconducting coil device according to this embodiment, with (a) being its cross-sectional view and (b) being an enlarged view of part D in (a).

[0044] In this embodiment, as shown in Fig. 6, the radial thickness of the axial reinforcing members 50 provided on the radial outer peripheral surfaces of the reinforcing wires 40e, 40f varies depending on the axial position, and the thickness at the positions closer to the axial center is relatively thicker than the thickness at the axial ends. Here, the axial center refers to the axial center of the superconducting coil 30 to be stacked.

[0045] The compressive stress in the axial direction of the superconducting coil 30 is highest near the axial center of the superconducting coil 30. In other words, when a plurality of superconducting coils 30 are stacked, the compressive stress acting on the superconducting coil 30 located in the center is the highest. In this embodiment configured as above, the radial thickness of the axial reinforcing member 50 becomes relatively thicker near the axial center where the compressive stress in the axial direction is higher.

[0046] With this configuration, it is possible to further suppress axial deformation of the superconducting coil 30, which is provided near the axial center of the stacked superconducting coils 30 and is subjected to high compressive stress, compared to the first to third embodiments. Therefore, even in the case where a high electromagnetic force is generated by a strong magnetic field, it is possible to stably pass current without deteriorating the superconducting characteristics.

[0047] According to at least one of the embodiments described above, reinforcing wires that are provided on the outer periphery of the superconducting coil and adjacent in the axial direction are connected to each other via an axial reinforcing member. With this configuration, even when a high electromagnetic force is generated due to a strong magnetic field, it is possible to suppress axial deformation of the superconducting coil and enable stable current flow without deteriorating the superconducting characteristics.

[0048] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0049] 10...Stacked high-temperature superconducting coil device, 20...winding frame, 30...superconducting coil, 30a...superconducting tape wire, 30b...insulating tape wire, 31...winding portion, 32...insulating layer, 33...tape substrate, 34...intermediate layer, 35...superconducting layer, 36...stabilizing layer, 37...orientation layer, 38...protective layer, 40, 40a, 40b, 40c, 40d, 40e, 40f...reinforcing wire material, 50, 50a, 50b...axial reinforcing member, 51...bolt nut, 52...extension portion.

Claims

1. a pancake coil including a pancake-shaped superconducting coil formed by concentrically winding a high-temperature superconducting tape wire around an insulating bobbin, and a reinforcing wire wound around the outermost periphery of the superconducting coil, the pancake coil being stacked in the axial direction; an axial reinforcing member disposed on a radially outer peripheral surface of the reinforcing wire, The reinforcing wires adjacent in the axial direction are connected to each other at least in part of their outer circumferential surfaces via the axial reinforcing member, The axial reinforcement member further has an extension portion extending in an inner circumferential direction so as to axially connect at least a portion of the surfaces of the opposing axial end portions of the axially adjacent reinforcing wires via the axial reinforcement member.

2. 2. The stacked high-temperature superconducting coil device according to claim 1, wherein the axial reinforcing member is formed by winding a metal plate material.

3. 3. The stacked high-temperature superconducting coil device according to claim 1, wherein the axial reinforcing member is formed by connecting a plurality of members.

4. 4. The stacked high-temperature superconducting coil device according to claim 1, wherein the thermal contraction rate of the front axial reinforcing member is greater than the thermal contraction rate of the superconducting coil.

5. 5. The stacked high-temperature superconducting coil device according to claim 1, wherein the front axial reinforcing member is made of a high-strength metal containing at least one of a copper alloy, an aluminum alloy, a stainless steel, and a nickel-based alloy.

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