Patent Grant
9552913
Field of the Invention
The present invention relates to a superconducting coil and a superconducting device, and in particular, to a superconducting coil that includes a plurality of laminated pancake coils and is used in a superconducting device, such as a superconducting magnet or a superconducting rotary machine, and a superconducting device including the superconducting coil.
Description of the Related Art
In a superconducting device, such as a superconducting magnet or a superconducting motor, a plurality of laminated pancake type superconducting coils may be used. Various structures, such as a structure in which laminated pancake type superconducting coils are cooled by heat conduction from a freezing machine or a structure in which laminated pancake type superconducting coils are cooled by coolant such as helium gas, have been suggested.
As a conventional example of a pancake type superconducting coil, a superconducting coil impregnated with resin for electromagnetic force reinforcement and a superconducting coil integrated by curing a glass fiber reinforced sheet, which is interposed between laminated pancake coils and contains semi-cured resin, is known (refer to Japanese Unexamined Patent Application, First Publication No. H6-151168).
In the conventional superconducting coil 100 in which the glass fiber reinforced sheet 108 and the pancake coil 105 are integrated as shown in
In particular, when a rare earth element-based oxide superconducting wire is used, it is generally difficult to detect the occurrence of the quench. For this reason, if a part of the superconducting wire that forms the pancake coil 105 is burnt, the entire superconducting coil 100 should be remanufactured. Therefore, there is a problem in that serious damage is caused in terms of time and cost.
In view of the damage in terms of time and cost, it is also possible to adopt the superconducting coil 100 in which the glass fiber reinforced sheet 108 and the pancake coil 105 are not integrated. However, in order to ensure the mechanical strength of the superconducting coil 100 and increase the thermal stability of the entire coil, it is desirable to integrate the pancake coil 105 impregnated with resin and the glass fiber reinforced sheet 108.
The present invention has been made in view of the above, and it is an object of the present invention to provide a superconducting coil, which includes a plurality of pancake coils formed by winding a superconducting wire and has a structure in which, even if a problem occurs in one or more of the assembled pancake coils for some reason, the pancake coil in which the problem has occurred can be replaced, and a superconducting device including the superconducting coil.
In order to solve the above-described problem, a superconducting coil according to a first aspect of the present invention includes: first and second pancake coils that are formed by winding a superconducting wire, are stacked in a thickness direction, and are adjacent to each other; and a cooling substrate that is provided in contact with an end surface of the first pancake coil and is separable into a plurality of cooling plates.
According to the superconducting coil described above, since the cooling substrate disposed on the end surface of the pancake coil can be separated into a plurality of cooling plates, the laminated pancake coils can be separated from each other by separating the plurality of cooling plates that form the cooling substrate from each other. For this reason, it is possible to remove a pancake coil in which a problem has occurred and replace the pancake coil with another new pancake coil. That is, it is possible to repair the superconducting coil without wasting a pancake coil in which no problem has occurred. Therefore, compared with the conventional technique in which all pancake coils are replaced when a problem occurs in one or more of the pancake coils, it is possible to repair the superconducting coil at low cost without creating waste.
In addition, a bonding element may be further provided. The cooling substrate may be interposed between the first and second pancake coils. The bonding element may bond the cooling substrate and the first pancake coil to each other and bond the cooling substrate and the second pancake coil to each other. The first and second pancake coils may be separable from each other by separation between the plurality of cooling plates.
In this case, even if the cooling plate and the pancake coil are bonded and integrated by the resin impregnated in the pancake coil in contact with the cooling plate, the laminated pancake coils can be easily separated from each other by separating the cooling plates from each other since the stacked cooling plates can be separated. For this reason, it is possible to ensure good thermal conductivity between the pancake coil and the cooling plate and to replace only the pancake coil in which a problem has occurred. Therefore, it is possible to minimize the damage in terms of time and cost of the superconducting wire and the pancake coil.
In addition, the first pancake coil and at least a pair of upper and lower cooling plates may be fixed by the bonding element, and the second pancake coil and at least a pair of upper and lower cooling plates may be fixed by the bonding element.
In addition, a freezing machine connected to the cooling substrate through a heat transfer member and a heat transfer connection member, which is provided in each of the plurality of cooling plates and is connected to the heat transfer member, may be further provided.
In this case, each plurality of cooling plates that forms the cooling substrate can be cooled by the freezing machine through the heat transfer connection member. For this reason, even in a structure in which cooling plates are simply laminated so as to overlap each other, each cooling plate can be efficiently cooled by the freezing machine, and each pancake coil connected to the cooling plate through the heat transfer connection member can be cooled efficiently. Therefore, it is possible to provide a superconducting coil having the same cooling efficiency as a conventional superconducting coil.
In addition, a bobbin including a pair of upper and lower flange portions, between which the first and second pancake coils are interposed in the thickness direction, and a body portion, which is provided between the pair of upper and lower flange portions and is inserted in the first and second pancake coils, may be further provided. Thermal expansion coefficients of the flange portions and the body portion may be larger than thermal expansion coefficients of the first and second pancake coils and a thermal expansion coefficient of the cooling substrate.
In addition, a bobbin including a pair of upper and lower flange portions, between which the first and second pancake coils are interposed in the thickness direction, and a body portion, which is provided between the pair of upper and lower flange portions and is inserted in the first and second pancake coils, may be further provided. The first and second pancake coils and the cooling substrate may be interposed between the pair of upper and lower flange portions so as to be compressed in the thickness direction by an amount larger than an amount of shrinkage in the thickness direction of the first and second pancake coils and the cooling substrate during cooling of the first and second pancake coils by the cooling substrate.
A superconducting device according to a second aspect of the present invention includes: the superconducting coil described above; an inner container surrounding the superconducting coil; a vacuum container surrounding the inner container; and a freezing machine passing through the vacuum container and the inner container. The cooling substrate is connected to a tip of the freezing machine, which extends to an inside of the inner container, through a heat transfer member. According to the superconducting device described above, it is possible to provide a superconducting device which includes a superconducting coil having a plurality of laminated pancake coils and in which the pancake coil can be cooled through the cooling substrate provided in contact with the pancake coil.
In addition, since the cooling substrate disposed on the end surface of the pancake coil is configured to include a plurality of cooling plates, the laminated pancake coils can be separated from each other by separating the plurality of stacked cooling plates from each other. That is, it is possible to remove only a pancake coil, in which a problem has occurred, among the assembled pancake coils and replace the pancake coil with another new pancake coil. For this reason, it is possible to minimize the damage in terms of time and cost of the superconducting wire and the pancake coil and to minimize the number of steps of remanufacturing the pancake coil. Therefore, according to the superconducting device according to this aspect, compared with the conventional technique in which all pancake coils should be replaced, it is possible to repair the superconducting coil quickly at a low cost.
According to the aspects of the present invention described above, since the cooling substrate disposed on the end surface (a top surface or a bottom surface) of the pancake coil includes a plurality of cooling plates, the laminated pancake coils can be separated from each other by separating the cooling plates from each other. For this reason, it is possible to remove only a pancake coil in which a problem has occurred and replace the pancake coil with another new pancake coil. Accordingly, it is possible to minimize the damage in terms of time and cost required for replacement of the superconducting wire and the pancake coil and to minimize the number of steps required for remanufacturing the pancake coil. Therefore, according to the aspect of the present invention described above, compared with the conventional technique in which all pancake coils should be replaced, it is possible to repair the superconducting coil quickly at a low cost.
Hereinafter, a superconducting magnet device including a superconducting coil according to an embodiment of the present invention will be described with reference to the diagrams. The present invention is not limited to the embodiment described below.
A superconducting magnet device 1 shown in
The freezing machine 8 has a two-stage structure including first and second stages 8A and 8B. A cooling plate 11A of the superconducting coil 5 is connected to a heat transfer body 9, which extends to the distal end of the second stage 8B and is formed in a rod shape, through three heat transfer members 15. Accordingly, the superconducting coil 5 is configured so as to be able to be cooled to the critical temperature or lower by the conduction cooling of the freezing machine 8.
In the example shown in
In the structure shown in
Although the pancake coil interposed between the upper and lower cooling plates is a double pancake coil in the present embodiment, a single pancake coil may be used, or a single pancake coil may be stacked in three or more layers.
The cooling plate 11A is formed of a metal material having good thermal conductivity, and has a thickness of approximately one severalth millimeter to several millimeters. The metal material that forms the cooling plate 11A is not particularly limited, and can be appropriately changed. For example, the cooling plate 11A is formed of copper, such as oxygen-free copper, tough pitch copper, and brass, a copper alloy, aluminum, or an aluminum alloy.
The superconducting coil 5 shown in
In addition, the number of cooling plates 11A fixed to the pancake coil 14 is not limited to two, and may be three or more as long as the cooling plates 11A can be separated from each other.
A protruding portion 11a that protrudes to the side of the pancake coil 14 is formed at one end (end close to the second stage 8B of the freezing machine 8) of the cooling plate 11A. A pair of heat transfer connection members 13 formed in a plate shape, between which distal portions of the protruding portions 11a of the cooling plates 11A overlapping each other in the vertical direction are interposed in the vertical direction, are provided on the uppermost surface and the lowermost surface in the distal portions of the protruding portions a. The heat transfer member 15 extending from the heat transfer body 9, which is present at a position close to the second stage 8B that forms the freezing machine 8, is interposed between a pair of heat transfer connection members 13. The heat transfer member 15 is connected to the second stage 8B of the freezing machine 8 through the heat transfer body 9 in order to perform conduction cooling from the second stage 8B that forms the freezing machine 8.
Although not shown in the diagram, a pair of heat transfer connection members 13, between which the protruding portions 11a are interposed in the vertical direction, and the protruding portions 11a are integrated by the bolt passing through the protruding portion 11a and the pair of heat transfer connection members 13 and the nut screwed to the bolt. The protruding portions 11a are interposed at one end of the pair of heat transfer connection members 13, and the heat transfer member 15 is interposed at the other end. By the bolt passing through the heat transfer member 15 and the pair of heat transfer connection members 13 and the nut screwed to the bolt, the pair of heat transfer connection members 13 and the heat transfer member 15 are integrated. The connection between the cooling plate 11A and the pair of heat transfer connection members 13 is not limited to the connection using the bolt and the nut, and it is also possible to use other connection structures.
The heat transfer body 9, the heat transfer connection member 13, and the heat transfer member 15 are formed of a metal material having good thermal conductivity. The metal material that forms the heat transfer body 9, the heat transfer connection member 13, and the heat transfer member 15 is not particularly limited, and can be appropriately changed. For example, the heat transfer body 9, the heat transfer connection member 13, and the heat transfer member 15 can be formed of copper, such as oxygen-free copper, tough pitch copper, and brass, a copper alloy, aluminum, or an aluminum alloy.
By connecting the protruding portion 11a formed in the cooling plate 11A to the second stage 8B thermally sufficiently through the pair of heat transfer connection members 13, the heat transfer member 15, and the heat transfer body 9 as described above, conduction cooling of the pancake coil 14 can be efficiently performed by the second stage 8B that forms the freezing machine 8.
In a conventional device, the cooling substrate 11 is formed using a single metal plate. On the other hand, in the present embodiment, the cooling substrate 11 is formed using the two cooling plates 11A. If the thickness of the cooling plate 11A is approximately ½ of the thickness of one metal plate in a conventional device, the total thickness of the superconducting coil 5 including the two stacked cooling plates 11A is the same as the total thickness of the superconducting coil having a conventional structure. For example, if the cooling plate 11A having a thickness of ½ of the thickness of the cooling substrate in a superconducting coil having a conventional structure is used, the current density of the entire superconducting coil 5 (=applied current×number of turns/cross-sectional area of the coil) is the same. Therefore, there is no influence on the coil characteristics, such as a reduction in the central magnetic field of the coil. In addition, even if the thickness of the cooling plate 11A is slightly larger than ½ of the thickness of the cooling substrate in a superconducting coil having a conventional structure, the influence on the thickness of the entire superconducting coil 5 is small. For this reason, a change in the coil current density due to the change in the coil height can also be slightly suppressed.
In the superconducting magnet device 1, external connection terminals 17 and 18 for supplying a current are formed so as to penetrate the flange portion 6. Lower ends of the external connection terminals 17 and 18 are pulled into the outer container 2, and are connected to an upper end of a current lead 19. A lower end of the current lead 19 is connected to an oxide superconducting wire (not shown) that forms each pancake coil 14 in the superconducting coil 5.
The outer container 2 is connected to a vacuum pump (not shown), so that the inside of the outer container 2 can be decompressed to the desired degree of vacuum. The external connection terminals 17 and 18 are connected to a power source (not shown), which is disposed outside the superconducting magnet device 1, through a current lead line, so that a desired magnetic field can be generated by the application of current from the power source to the superconducting wire in the superconducting coil 5.
As an example of the superconducting wire wound around the pancake coil 14, it is possible to use any superconducting wire that is generally referred to as a high-temperature superconducting wire, such as a rare earth element-based oxide superconducting wire, a Bi-based oxide superconducting wire, or an MgB2 superconducting wire.
As the rare earth element-based oxide superconducting wire, a superconducting wire formed in a tape shape by laminating an intermediate layer, an oxide superconducting layer, a protective layer, and a stabilization layer on a metal-tape substrate can be illustrated.
The intermediate layer can have a multi-layer structure including a diffusion barrier layer or a bed layer as a base layer. As an alignment layer that is the main body of the intermediate layer, it is possible to use a thin film with good crystal orientation that is formed using a physical vapor deposition method, such as an ion beam assisted deposition method (hereinafter, abbreviated as an IBAD method). In order to obtain better crystal orientation, it is possible to provide a cap layer on the alignment layer.
When a thin film formed of rare earth element-based oxide superconductor is applied to the intermediate layer, REBa2Cu3Oy (RE indicates rare earth elements, such as Y, La, Nd, Sm, Er, and Gd), specifically, Y123 (YBa2Cu3Oy), Gd123 (GdBa2Cu3Oy), or the like can be illustrated.
The protective layer formed so as to cover the surface of the oxide superconducting layer can be formed of Ag or an Ag alloy, and the stabilization layer laminated on the protective layer can be formed of Cu or a Cu alloy having good conductivity.
As an example of the Bi-based oxide superconducting wire, it is possible to use a superconducting wire that is formed in a tape shape by mixing a sintered body that can be expressed as BiSrCaCuO, such as a 2223 phase, inside a metal sheath formed of metal having good conductivity, such as Ag, and performing rolling.
As an example of the MgB2 superconducting wire, it is possible to use a superconducting wire that is formed in a tape shape or a linear shape by including the powder of MgB2 inside a metal pipe and forming multiple cores using a powder-in-tube method for reducing the diameter.
The superconducting magnet device 1 shown in
The superconducting magnet device 1 shown in
In the superconducting magnet device 1, the cooling substrate 11 includes the two cooling plates 11A. The two cooling plates 11A simply overlap each other. For this reason, there is a possibility of the deterioration of thermal contact between the cooling plates 11A. However, the protruding portion 11a formed in the cooling plate 11A is integrated with a pair of heat transfer connection members 13 between which 11a is interposed in the vertical direction. That is, two cooling paths through a pair of heat transfer connection members 13 disposed on the uppermost surface and the lowermost surface of the protruding portions 11a are provided. Therefore, it is possible to separately perform conduction cooling of the cooling plate 11A from the heat transfer member 15 through the pair of heat transfer connection members 13. Accordingly, heat transfer efficiency of the cooling plate 11A is not reduced.
In addition, it is preferable to set the thickness of the cooling plate 11A to approximately ½ of the thickness of one cooling substrate in a conventional structure. However, when the cooling plate 11A is formed thicker, the thickness of the entire superconducting coil 5 is increased, but an increase in the thickness of the cooling plate 11A with respect to the thickness of the entire superconducting coil 5 is small. For this reason, a decrease rate of the number of windings in the oxide superconducting wire caused by the increase in the thickness of the superconducting coil 5 is very small, and a reduction in the current density of the superconducting coil 5 is small. Therefore, there is no adverse effect on the performance of the superconducting coil 5.
In the superconducting magnet device 1, when a problem occurs in the oxide superconducting wire, only the pancake coil 14 in which the problem has occurred in the superconducting wire between the two laminated pancake coils 14 shown in
For this reason, it is not necessary to replace the entire superconducting coil 5. Therefore, the pancake coil 14 in which no problem has occurred in the superconducting wire is not needlessly discarded.
Incidentally, although the superconducting coil 5 shown in
In addition, although the superconducting coil 5 shown in
In addition, although the superconducting coil 5 shown in
The superconducting coil 20 shown in
The superconducting coil 20 shown in
The superconducting coil 20 shown in
A plurality of superconducting coils 35 are attached around a central portion of a rotary shaft 33. A plurality of normal conduction coils 36 formed by copper coils supported by the inner wall of the container 31 are disposed around the plurality of superconducting coils 35.
A plurality of pipes for inflow and outflow of cooling gas are provided inside the rotary shaft 33. Therefore, the superconducting coil 35 can be cooled to the critical temperature or lower by the cooling gas that is introduced from a refrigerant supply device (not shown), which is separately provided outside the superconducting motor 30, into the container 31 through the plurality of pipes. Although the superconducting coil 35 is cooled to the critical temperature or lower, the normal conduction coil 36 is held at room temperature.
As shown in
The superconducting motor 30 shown in
When a problem occurs in a superconducting wire assembled in any of the superconducting coils 35 for some reason during the use of the superconducting motor 30 shown in
The bobbin B shown in
It is preferable that the thermal expansion coefficients of the flange portion B1 and the winding drum (body portion) B2, which form the bobbin B shown in
As shown in
A superconducting coil having a structure shown in Table 1 below was manufactured.
An oxide superconducting wire having a total thickness of approximately 0.23 mm configured to include a tape-shaped substrate having a width of 5 mm and a thickness of 0.1 mm that was formed of Hastelloy C276 (product name of U.S. Haynes Co.) and a diffusion barrier layer of Al2O3 having a thickness of 100 nm, a bed layer of Y2O3 having a thickness of 30 nm, an alignment layer of MgO having a thickness of 10 nm, a cap layer of CeO2 having a thickness of 500 nm, an oxide superconducting layer of GdBa2Cu3O7-x having a thickness of approximately 2 μm, a protective layer of Ag having a thickness of 10 μm, and a copper-bonded tape having a thickness of 100 μm, which were provided on the surface of the substrate, was prepared.
A pancake coil was formed by turning the above-described superconducting wire 100 turns around the winding drum and a winding portion was impregnated with epoxy resin and was cured, thereby forming a superconducting coil. Then, the superconducting coil was immersed into liquid nitrogen and a critical current was measured. Then, the superconducting coil was assembled into the superconducting magnet device having the structure shown in
The specification is shown in Table 1 below.
From the result shown in Table 1, a result was obtained in which the value of the central magnetic field and characteristics as a superconducting magnet device were the same between the conventional superconducting coil and the superconducting coil of this example. According to the structure of this example, two cooling plates that form the cooling substrate can be separated from each other. Accordingly, when a problem occurs in one of the pancake coils, only the pancake coil in which the problem has occurred is replaced. Therefore, since it is not necessary to replace all pancake coils in the superconducting magnet device of this example, the superconducting magnet device of this example is advantageous when fixing the superconducting magnet device compared with a superconducting magnet device having a conventional structure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-049411 | Mar 2012 | JP | national |
This application is a continuation application based on a PCT Patent Application No. PCT/JP2013/056129, filed Mar. 6, 2013, whose priority is claimed on Japanese Patent Application No. 2012-049411, filed on Mar. 6, 2012, the entire content of which are hereby incorporated by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5396205 | Takahashi et al. | Mar 1995 | A |
| 20100148625 | Okazaki et al. | Jun 2010 | A1 |
| Number | Date | Country |
|---|---|---|
| 6-151168 | May 1994 | JP |
| 11-176629 | Jul 1999 | JP |
| 11-186025 | Jul 1999 | JP |
| 2007037343 | Feb 2007 | JP |
| 2009-44013 | Feb 2009 | JP |
| 2009-188065 | Aug 2009 | JP |
| 2010-171152 | Aug 2010 | JP |
| 2109361 | Apr 1998 | RU |
| Entry |
|---|
| Machine Translation of JP 2009-044013, pp. 1-9. |
| Machine Translation of JP2010-171152, pp. 1-12. |
| Machine Translation of JP2009-188065, pp. 1-12. |
| Machine Translation of JP11-186025, pp. 1-13. |
| Takao T et al: “Mechanical Loss and Bobbin Materials in AC Superconducting Coil Under AC Magnetic Field”, IEEE Transactions on Applied Superconductivity, vol. 21, No. 3, Jun. 1, 2011, pp. 2420-2423, DOI:10.1109/TASC.2010.2091240. |
| Communication dated Nov. 5, 2015 from the European Patent Office in counterpart application No. 13758274.8. |
| Communication dated Dec. 8, 2015 from the Russian Patent Office in counterpart application No. 2014136146/07. |
| Communication dated Aug. 25, 2015 from the European Patent Office in counterpart European Application No. 13758274.8. |
| Communication dated Mar. 17, 2015 from the Japanese Patent Office in counterpart application No. 2014-503880. |
| International Search Report for PCT/JP2013/056129 dated Jun. 18, 2013 [PCT/ISA/210]. |
| Written Opinion for PCT/JP2013/056129 dated Jun. 18, 2013 [PCT/ISA/237]. |
| Communication dated May 6, 2016, from the Russian Patent Office in counterpart application No. 2014136146. |
| Communication dated Nov. 18, 2014 from the Japanese Patent Office in counterpart application No. 2014-503880. |
| English-language translation of JP 2010171152 of record, 2015. |
| English-language translation of JP 2009188065 of record, 2015. |
| English-language translation of JP 11186025 of record, 2015. |
| Number | Date | Country | |
|---|---|---|---|
| 20140357492 A1 | Dec 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2013/056129 | Mar 2013 | US |
| Child | 14460991 | US |
