JP2560561C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting coil device having improved stability and improved quench resistance of a closely wound superconducting coil. 2. Description of the Related Art Conventionally, as a method for preventing coil quenching due to disturbance on a winding surface of a closely wound superconducting coil, as described in Japanese Patent Application Laid-Open No. 1-1194308, a superconducting coil and a refrigerant are incorporated. There is known a method of inserting a spring member between coiled containers to suppress the movement of the coil due to vibration, thereby preventing quench of the superconducting coil due to frictional heat. Further, as described in JP-A-57-124406 and JP-A-57-178306, a low friction material is inserted between the superconducting coil and the insulating material on the inner surface of the coil container to reduce the generation of frictional heat. As described in JP-A-57-63809, a heat insulating member composed of an insulator having a small friction coefficient and a low thermal conductivity is provided at predetermined intervals on the surface of a superconducting coil, and the coil is supported on a coil container. A superconducting coil is fixed to an inner container via a metal pipe through which a cryogenic refrigerant flows, as described in JP-A-57-63808. Thus, there is known a method of preventing quenching due to intrusion of frictional heat from the surface of the superconducting coil. [0003] The above-mentioned prior arts are all methods for reducing disturbance which causes the quench of the superconducting coil and making it difficult to transmit heat generated by the disturbance to the superconducting coil. In reality, the quench resistance of the closely wound superconducting coil has hardly been improved. That is, it is understood that none of the conventional techniques is still sufficient to prevent the quench of the superconducting coil. [0004] An object of the present invention is to provide a superconducting coil device which eliminates the above-mentioned disadvantages of the prior art and has improved quench resistance. [0005] The superconducting magnetic levitation train has a superconducting coil on the upper side of the car and a normal-conducting short-circuit coil on the ground side, and electromagnetic induction is provided between the superconducting coil and the ground coil when the vehicle is running. Is caused by the repulsive force generated by On the other hand, the propulsion of the vehicle is a linear synchronous motor system, and the propulsion of the same coil is obtained by reversing the current of the propulsion coil by the interaction between the normal conduction propulsion coil separately provided on the ground side and the superconducting coil on the vehicle Things. A superconducting coil used in a superconducting maglev train generally has a race track shape as shown in FIG. 5, and is mounted on a vehicle, so that it is required to be as light and small as possible from the viewpoint of economy. . For this purpose, it is required to make the superconducting coil winding part as compact as possible and to increase the coil current density. Therefore, as shown in FIG. 6, the refrigerant such as liquid helium is placed in the space 3 formed by the refrigerant container 1 and the insulator 2, and the coil winding part 4 has a close-wound structure without the refrigerant directly in contact with the superconducting wire. In addition, a so-called low copper ratio superconducting wire in which the volume other than the portion where the current is applied, for example, the volume of the stabilizing material or the like is minimized is used. On the other hand, a superconducting coil for a magnetic levitation train requires a high degree of reliability and stability to transport passengers safely. For this purpose, it is essential that the stability margin of the superconducting coil is larger than the disturbance energy. This stability margin is the minimum energy required to quench the superconducting coil. However,
The tightly wound low copper ratio superconducting coil has a small stability margin and may cause quench with a small amount of disturbance energy. In particular, since the superconducting coil for a magnetically levitated train is used in a high-speed running state, it is subjected to severe disturbing energy due to movement of the superconducting coil due to mechanical vibration, impact load due to tunnel or train passing, wind pressure, vibration and the like. Used under appropriate conditions. However, a specific method for stably operating a tightly wound superconducting coil, as well as a stabilization theory for a tightly wound superconducting coil, which can easily specify from which part in the coil winding the quench occurs, has not yet been established. The present inventors have found that the above problem can be solved by locally increasing the stability margin of the coil winding portion which is easily quenched. That is, it has been clarified that the quenching resistance of the superconducting coil can be greatly improved by increasing the stability margin of only the winding surface portion so as not to quench from the winding surface. More specifically, the quench resistance of the superconducting coil can be improved by making the stability margins at both ends of the coil winding larger than the stability margins of other portions of the coil winding. [0013] Furthermore, even if the stability margin of the entire coil winding surface is increased so as not to quench from the coil winding surface, the quench resistance of the superconducting coil can be greatly improved. As a means for changing the stability margin between the coil winding surface and other portions, there is a method of changing a stabilizing base material of a superconducting wire to be used. That is, this is achieved by making the cross-sectional area of the superconducting wire on the winding surface larger than the cross-sectional area of the superconducting wire in the other part. It is also achieved by actively introducing high-purity aluminum. On the other hand, as means for improving the stability of the coil winding surface, it is not always necessary to use a superconducting wire having a high stability margin on the winding surface. The stability margin may be increased. Another point of interest of the present invention is based on this idea, in which a normal conductive metal such as copper or aluminum is wound on the surface of the coil winding of the superconducting wire, and a stability margin is formed between the surface of the coil winding and other parts. May be changed. The superconducting coil for a magnetically levitated train is subjected to various disturbances such as movement of the superconducting coil due to electromagnetic force and mechanical vibration during high-speed running, shock load due to a tunnel or train passing, wind pressure, vibration, and the like. A place where the superconducting coil is easily quenched is in the coil winding or on the surface of the coil winding. The winding of the superconducting coil has a tightly wound structure,
Since the superconducting wire is impregnated with the epoxy resin, the movement of the superconducting wire due to the electromagnetic force or the like can be largely suppressed, so that quenching is difficult. On the other hand, the coil winding surface is easily quenched by disturbance caused by heat generated by friction between the insulator and the coil winding. Therefore, if the stability margin of the entire coil winding surface is increased so as not to quench from the coil winding surface, the quench resistance of the superconducting coil can be greatly improved. As shown in FIG. 6, the winding cross section of the superconducting coil for a magnetic levitation train is generally rectangular, and the coil winding 4 has both ends 7 of the coil winding and other portions 5 of the coil winding.
Can be roughly divided into When a magnetic levitation train runs at high speed, the coil is analyzed for complex vibration modes such as rolling, pitching, and yawing, as described later, and quenching is suppressed by increasing the stability margin of the coil winding surface at the required points. it can. As a means of changing the stability margin between the surface of the coil winding and other parts, there is a method of changing the amount of the stabilizing base material of the superconducting wire to be used. This is achieved by making the cross-sectional area larger.
It is also achieved by actively introducing high-purity aluminum. That is, high-purity aluminum has an electrical resistivity of about 1 /
It is excellent as a stabilizing base material because it is difficult to form hot spots because it is as small as 10 and the thermal conductivity is about 6.4 times that of high-purity copper, and aluminum is lighter because aluminum has a lower specific gravity than copper. It has characteristics. Therefore, by coating the required amount of high-purity aluminum on the surface of the superconducting wire using copper as a stabilizing base material on the surface of the coil winding, it is possible to locally increase the stability margin. Further, considering a case where the superconducting coil is operated in the permanent current mode like a magnetic levitation train, it is more stable and current decay rate of the coil to have no connection portion of the superconducting wire in the coil winding. It is also preferable from the viewpoint of. This is achieved by coating the required amount of high-purity aluminum on the surface of the connection-free superconducting wire using copper as a stabilizing base material. In particular, in the case of a magnetically levitated train, when traveling at high speed, the superconductivity can be calculated by taking orthogonal coordinates with the origin of the coil of the superconducting coil mounted on the vehicle as the origin and the propulsion direction of the train as the x axis and the upward direction as the z axis. Propulsion force (Fx) and guide force (Fy) between the coil and the ground coil
, A vertical force (Fz) acts. On the other hand, rolling moments (Mx) and pitching moments (M
y), the force of the yawing moment (Mz) acts. The magnetic levitation train is now 500k
As a result of analyzing the force and moment applied to the superconducting coil by the current induced by the levitating coil when traveling at a constant speed of m / h and obtaining the ratio, the F
x: Fy: Fz = 1: 0.9: 2.4, Mx: My: Mz = 1: 2.1: 1.4,
All were found to have the same order value. Therefore, the combined force of these forces and each moment acts on the superconducting coil, causing relative displacement between the superconducting coil and its coil container, generating frictional heat.As described above, the same frictional heat is generated on all coil winding surfaces. I found out. Therefore, in order to make the magnetic levitation train run more stably, it is preferable to increase the stability margin of all coil winding surfaces. Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 1 shows a cross-sectional configuration of a superconducting coil in an apparatus according to the present invention.
In FIG. 1, a coil winding part 4 is composed of a winding central part 9 and a winding surface part 8, is fixed to a refrigerant container 1 via an insulating material 2, and is cooled by a liquid helium 3 as a refrigerant. Example 1 First, a superconducting wire B was formed on both sides 8 of the winding in FIG. 1 and a superconducting wire A was formed on the other part 9 of the winding as shown below. That is, the superconducting wire A is obtained by embedding 1748 NbTi filaments having a diameter of 27 μm embedded in high-purity copper at a twist pitch of 21 mm by a known method and processing it to an outer dimension of 1.1 mm × 1.9 mm. 40
A superconducting wire insulated with μm polyvinyl formal and having a copper ratio (= stabilized copper amount / superconductor amount) of 1.0. On the other hand, the superconducting wire B is formed by coating the surface of the superconducting wire A with 99.999% high-purity aluminum by an extrusion method to a thickness of 0.3 mm to form an outer dimension of 1.7 mm × 2.5 mm, and then forming a 25 μm thick One polyimide tape
/ 2 overlapped each other for insulation. The superconducting wire A and the superconducting wire B are wound while being connected by soldering so that both ends 8 of the winding form four layers from the coil surface in the configuration of FIG. After a circular superconducting coil having a length of about 210 mm, a length of about 90 mm, 36 layers, a total number of turns of 1170, and an inductance of 0.165 Henry was closely wound, an epoxy resin was impregnated in a vacuum to obtain a superconducting coil P. The coil section of the obtained superconducting coil was configured such that its dimensions and cooling conditions were substantially the same as those of the superconducting coil for a magnetic levitation train. A heater formed by winding a silk-wrapped manganin wire non-inductively over a conductor longitudinal direction of 1 cm is embedded at both ends 8 of the coil. In order to experimentally verify the stability of the superconducting coil according to the present invention, the above copper ratio of 1.0 was used.
Using only the superconducting wire A, and wound and immersed in epoxy resin so as to have the same specifications as the superconducting coil P as much as possible. The inner diameter is 100 mm, the outer diameter is 192 mm, and the length is 68 mm.
The number of layers, the number of turns, the number of turns, 1170, and the inductance 0.163 Henry's close-wound superconducting coil Q was separately manufactured. In this superconducting coil Q, a heater is embedded similarly to the superconducting coil P. When the superconducting coil P and the superconducting coil Q were immersed in liquid helium and DC-excited, all could excite up to 100% of the magnetic field-critical current characteristics of the superconducting wire. Further, in order to compare the stability of the superconducting coil with respect to disturbance due to friction or the like on the coil winding surface, a heater pulse of about 10 ms was applied to the heater of the superconducting coil P and the superconducting coil Q, and the stability margin was measured. As a result, the stability margin at a coil current load factor of 70% was 22 mJ / cm for the superconducting coil P, whereas the stability margin for the superconducting coil Q was 3.0 mJ / cm. Has a stability margin about 7 times higher than that of the superconducting coil Q. Example 2 The superconducting wire A and the superconducting wire B shown in Example 1 were prepared, and the superconducting wire B was replaced with the superconducting wire B so that the winding surface 10 constituted four layers from the coil surface in the configuration of FIG. Wound. On the other hand, the superconducting wire A is wound while being connected by soldering so as to form a portion 11 other than the winding surface 10 in FIG. 2, and the same processing as that of the superconducting coil R of the first embodiment is performed. A coil R was obtained. In this superconducting coil R, the same heater as that described in the first embodiment is embedded in the winding surface 10. When the stability margin was measured in the same manner as in Example 1, the superconducting coil P described in Example 1 was measured.
A similar stability margin was obtained. Example 3 652 NbTi filaments having a diameter of 45 μm were buried in high-purity copper at a twist pitch of 36 mm, the outer dimensions were 1.92 mm × 2.8 mm, and the surface was insulated with polyvinyl formal of about 40 μm. A 3.9 superconducting wire C was separately manufactured. A superconducting coil R ′ having substantially the same specifications as the coil shown in the first embodiment, using the superconducting wire A described in the first embodiment in the center portion 11 of the winding and the superconducting wire C in the winding surface 10 in FIG. Was made. The same heater as that described in the first embodiment is embedded in this superconducting coil R '. When the stability margin of the superconducting coil R ′ at a current load factor of 70% was measured in the same manner as in Example 1, it was about 7.8 mJ / cm, and the copper ratio described in Example 1 was 1.0. Has a stability margin about 2.4 times higher than that of the superconducting coil Q using the superconducting wire A. Fourth Embodiment High-purity aluminum is reduced to 0 at a predetermined position on the surface of a superconducting wire A shown in the first embodiment by the same method as in the first embodiment so that the same specifications as the superconducting coil P of the first embodiment are obtained. A non-connected superconducting wire D wound in a length direction covered with a thickness of 0.3 mm is impregnated with an epoxy resin in a vacuum, and a superconducting coil S having substantially the same specifications as the superconducting coil P described in Example 1 is obtained. Was. When a stability margin was measured using a heater having the same specifications as in Example 1, a stability margin equivalent to that of the superconducting coil P described in Example 1 was obtained. Further, a superconducting-superconducting connection was made to the superconducting coil S and a separately manufactured permanent current switch to form a closed loop, and the apparatus was operated in a permanent current mode at a current of 500 A for about 200 hours, but was operated stably without quenching. When the time constant of the current decay at this time was evaluated, it was about 5 × 10 ¹¹ seconds. Fifth Embodiment A superconducting wire A shown in a first embodiment is prepared in advance, and a method similar to that of the first embodiment is provided at a predetermined position located on the coil winding surface 10 in FIG. , A non-connected superconducting wire E in the length direction was formed by coating high-purity aluminum having a purity of 99.999% with a thickness of 0.3 mm. This superconducting wire E is wound so as to have the coil cross-sectional configuration shown in FIG. 2 of the second embodiment, and then impregnated with an epoxy resin in a vacuum, and is stabilized by a heater having substantially the same specifications as the superconducting coil P described in the first embodiment. When the margin was measured, a stability margin equivalent to that of the superconducting coil S described in Example 4 was obtained. The superconducting coil U and the permanent current switch separately manufactured were connected to each other by superconducting-superconducting connection to form a closed loop, and were operated in a permanent current mode at a current of 500 A for about 200 hours, but operated stably without quench. When the time constant of current decay at this time was evaluated, a result equivalent to that of the example was obtained. Embodiment 6 The same superconducting wire A and superconducting wire B used for the superconducting coil P shown in Embodiment 1 are used to make the superconducting coil have the same winding cross-sectional structure as the superconducting coil R of Embodiment 2. The wire A and the superconducting wire B were wound while performing superconducting-superconducting connection, and then subjected to an impregnation treatment, thereby producing a superconducting coil V having substantially the same specifications as the superconducting coil of Example 2. The superconducting coil V also has a heater embedded in the same place as the superconducting coil P. When the stability margin of the superconducting coil V was evaluated by the same method as in Example 1, a value similar to that of the superconducting coil P was obtained. The time constant of the current decay of the superconducting coil V measured using the method shown in the fourth embodiment was almost the same as that of the fourth embodiment. Embodiment 7 The same superconducting wire A and superconducting wire B as those used for the superconducting coil P shown in Embodiment 1 are used so that the superconducting coil has the same winding cross-sectional structure as the superconducting coil R of Embodiment 2. The wire A and the superconducting wire B were wound while performing superconducting-superconducting connection, and then subjected to an impregnation treatment, thereby producing a superconducting coil W having substantially the same specifications as the superconducting coil of Example 2. The superconducting coil W also has a heater embedded in the same place as the superconducting coil R. When the stability margin of the superconducting coil W was evaluated by the same method as in Example 1, a value similar to that of the superconducting coil R was obtained. Using the method shown in the fourth embodiment, the time constant of the current decay of the superconducting coil W was almost the same as that of the fourth embodiment. Example 8 A copper wire having the same outer diameter and insulation as the superconducting wire A described in detail in Example 1 was manufactured in advance. Two normal-conducting metal wire winding portions 13 (13 in FIG. 3) formed by winding two layers using this copper wire and impregnating with an epoxy resin were prepared. Further, a superconducting winding section 12 (12 in FIG. 3) formed by winding the superconducting wire A shown in the first embodiment so as to have almost the same specifications as the superconducting coil Q is prepared, and the copper wire is used. After being arranged so as to constitute FIG. 3 together with the normal-conducting metal wire winding portion 13, the superconducting coil X was manufactured by further impregnating epoxy resin in a vacuum. The heater described in the first embodiment is similarly buried in the normal conducting wire metal winding 13 using the copper wire. As in Example 1, energy was applied to the heater up to 30 mJ / cm at a coil current load rate of 70%, but the superconducting coil operated stably without quenching. Example 9 A high-purity 99.999% aluminum wire having the same dimensions as the copper wire of Example 8 was manufactured, and a 25 μm-thick polyimide tape was overlapped on the surface thereof by 1/2 for insulation. I prepared something. This was used in place of the copper wire of Example 8 to produce a superconducting coil X. A heater similar to that of the eighth embodiment is embedded in the normal conducting metal wire winding portion 13 using the high-purity aluminum wire. As in Example 1, energy was applied to the heater up to 40 mJ / cm at a coil current load factor of 70%, but the superconducting coil operated stably without quenching. Example 10 A copper wire having the same outer diameter and insulation as the superconducting wire A described in detail in Example 1 was manufactured. After that, two layers of the copper wire are wound around a coil winding frame to form a normal conducting metal wire winding portion 14 (14 in FIG. 4), and then the superconducting wire A described in detail in the first embodiment is connected to the superconducting coil Q. The superconducting winding part 10 (10 in FIG. 4) was wound so as to have almost the same specifications. Further, the copper wire was wound around this outside in two layers to form a normal conducting metal wire winding portion 15 (15 in FIG. 4). Further, two normal-conducting metal wire winding portions 13 (13 in FIG. 4) formed by winding the copper wire in two layers and impregnating with epoxy resin were prepared. After arranging these components as shown in the figure, epoxy resin was further impregnated in a vacuum to produce a superconducting coil Z. The normal conductive metal wire winding portion 13 using the copper wire has
The heater described in detail in the first embodiment is similarly buried. As in Example 1, energy was applied to the heater up to 30 mJ / cm at a coil current load rate of 70%, but the superconducting coil operated stably without quenching. Example 11 A high-purity 99.999% aluminum wire having the same dimensions as the copper wire of Example 8 was manufactured, and a 25 μm-thick polyimide tape was overlapped on the surface by 1/2 for insulation. I prepared something. This was used in place of the copper wire of Example 10 to produce a superconducting coil Z '. A heater similar to that of the eighth embodiment is embedded in the normal-conducting metal wire winding portion 13 (13 in FIG. 4) using a high-purity aluminum wire. As in Example 1, energy was applied to the heater up to 40 mJ / cm at a coil current load factor of 70%, but the superconducting coil operated stably without quenching. In the above-mentioned embodiments 8 to 11, the embodiment using the copper wire and the aluminum wire has been described. However, instead of the above-described normal metal wire, a normal conductive metal plate such as copper and aluminum having a penetrating portion is used. May be configured. According to the present invention, a compact superconducting coil device having high stability, high reliability, and high current density and a magnetic levitation train device using the same can be obtained. The social ripple effect is great.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional configuration diagram of a superconducting coil showing one embodiment of the present invention. FIG. 2 is a cross-sectional configuration diagram of a superconducting coil showing another embodiment of the present invention. FIG. 3 is a sectional structural view of a superconducting coil showing another embodiment of the present invention. FIG. 4 is a sectional configuration diagram of a superconducting coil showing another embodiment of the present invention. FIG. 5 is a perspective view schematically showing a general race track type superconducting coil. 6 is a sectional view taken along the line AA 'of FIG. [Description of Symbols] 1 ... refrigerant container, 2 ... insulator, 3 ... refrigerant, 4 ... superconducting coil winding, 5 ... inner circumference of coil winding, 6 ... outer circumference of coil winding, 7, 8 ... coil Both ends of winding, 9: winding part, 10: coil winding surface, 11: other part of coil winding surface, 12: superconducting wire winding part, 13, 14, 15 ... normal superconducting metal wire winding part .

Claims (1)

Claims: 1. A coil winding in which a superconducting wire and a refrigerant are in contact with each other via an interposition, a cooling container surrounding the coil winding, and insulation between the coil winding and the cooling container. In a closely wound superconducting coil made of a material, the stability margins at both ends of the coil winding are made larger than those of other parts, and copper is used as a stabilizing material for the superconducting wire on the surface of the coil winding, and A superconducting coil device comprising a wire coated with aluminum. 2. A dense coil comprising: a coil winding in which a superconducting wire and a refrigerant are in contact with each other via an interposition; a cooling container surrounding the coil winding; and an insulator between the coil winding and the cooling container. In a wound superconducting coil, the stability margin of the entire surface of the coil winding is made larger than other portions of the coil winding, and copper is used as a stabilizing material for the superconducting wire on the surface of the coil winding. A superconducting coil device coated with aluminum. 3. The superconducting coil device according to claim 1, wherein a cross-sectional area of the superconducting wire on the surface of the coil winding is larger than other portions. 4. A dense coil comprising a coil winding in which a superconducting wire and a refrigerant are in contact with each other via an intervening member, a cooling container surrounding the coil winding, and an insulator between the coil winding and the cooling container. In the wound superconducting coil, the stability margins at both ends of the coil winding are made larger than other parts, and the surface of the coil winding and the other parts of the coil winding are connected to each other with different stability margins. A superconducting coil device characterized by being wound with a superconducting wire. 5. A dense coil comprising: a coil winding in which a superconducting wire and a refrigerant are in contact with each other via an interposition; a cooling container surrounding the coil winding; and an insulator between the coil winding and the cooling container. In the wound superconducting coil, the stability margin of the entire surface of the coil winding is made larger than that of the other part of the coil winding, and the surface of the coil winding and the other part of the coil winding are each provided with a stability margin. A superconducting coil device characterized by being wound by a different unconnected superconducting wire. 6. A dense coil comprising: a coil winding in which a superconducting wire and a refrigerant are in contact with each other via an interposition; a cooling vessel surrounding the coil winding; and an insulator between the coil winding and the cooling vessel. In the wound superconducting coil, the stability margins at both ends of the coil winding are made larger than other portions, copper is used as a stabilizer for the superconducting wire on the surface of the coil winding, and the superconducting wire is coated with aluminum. A superconducting coil device, wherein the surface of the coil winding and the other part of the coil winding are wound by unconnected superconducting wires having different stability margins.