JP2007089345A - Cooling structure of superconducting motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small/lightweight cooling structure of a superconducting motor which can be manufactured easily and maintained easily. <P>SOLUTION: The cooling structure of a superconducting motor comprising a rotor rotating about a shaft and a stator in which a superconducting coil generating a magnetic field for rotating the rotor is arranged comprises a mechanism 2 for conduction cooling the superconducting coil 3 wherein the superconducting coil 3 arranged in the stator is at least one of a field coil and an armature coil. The conduction cooling mechanism 3 has a refrigerating machine 20, and a conduction cooling terminal 21 connected with the refrigerating machine 20 and the superconducting coil 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling structure for a superconducting motor. In particular, the present invention relates to a cooling structure for a superconducting motor in which conduction cooling is applied to the cooling structure.

  Recently, it has been proposed to use a superconducting coil for a field coil or an armature coil which is a constituent member of a motor. When the superconducting coil is applied to the motor, it is possible to compensate for the drawbacks of the normal conducting material such as energy loss due to electric resistance. Moreover, since the conducting wire which comprises a superconducting coil has remarkably large electric power transmission per unit cross-sectional area compared with the conducting wire made from the normal conducting material, the high output of a motor is realizable.

  As a conventional superconducting motor to which a superconducting coil is applied as described above, for example, the one described in Patent Document 1 can be cited. A conventional superconducting motor uses a superconducting material for a coil disposed on a stator (stator), and a cryogenic refrigerant (for example, liquid nitrogen, liquid hydrogen, etc.) is circulated in the stator so that the superconducting coil is used. A cooling structure for cooling is provided. Recently, a cooling structure has been proposed in which a superconducting coil is disposed also in a rotor (rotor), a refrigerant is circulated in the rotor, and the superconducting coil is cooled. In the cooling structure that circulates the refrigerant, there is no refrigerant holding section that holds the refrigerant and a double section of a vacuum holding section that covers the outer periphery of the refrigerant holding section and holds a vacuum and suppresses the temperature rise of the refrigerant. Don't be.

  Here, when the sealing of the refrigerant holding section is broken, the refrigerant leaks from the refrigerant holding section, and there is a possibility that the superconducting state cannot be maintained in a relatively short time. On the other hand, when the sealing of the vacuum holding section is broken, the heat insulation performance between the two sections is rapidly lowered, and there is a possibility that the superconducting state cannot be maintained as in the case where the sealing of the refrigerant holding section is broken. Therefore, these refrigerant | coolant holding | maintenance division and vacuum holding | maintenance division are comprised by the sealed structure which has high airtightness.

JP-A-2005-57935

  However, in the cooling structure of the superconducting motor as described above, the outlet of the connecting wire between the superconducting motor such as a power line for supplying power to the superconducting coil and the outside must be provided in both the refrigerant holding section and the vacuum holding section. In addition, the cooling structure of the superconducting motor becomes complicated and takes time to manufacture. Moreover, in addition to providing the refrigerant holding section in the superconducting motor, such a cooling structure must be provided with a tank for storing the refrigerant outside the superconducting motor and a pump for circulating the refrigerant, It is difficult to reduce the size and weight of superconducting motors including these cooling structures. Further, the maintenance opportunity increases by the amount of the refrigerator, tank, and pump, and when the motor is repaired, the refrigerant must be extracted from the refrigerant holding section of the motor, which is very laborious. Further, the superconducting motor is not easily broken due to vibration when the motor is operated, such as the sealing at the outlet of the connecting wire described above is easily broken, and the refrigerant is vibrated by the vibration accompanying the rotation of the motor and the circulation of the refrigerant is hindered. It may not be possible to drive stably.

  Accordingly, a main object of the present invention is to provide a cooling structure for a superconducting motor capable of cooling a superconducting coil without using a fluid refrigerant.

  Another object of the present invention is to provide a cooling structure for a superconducting motor that can be easily manufactured in a small size and light weight and is easy to maintain.

  Furthermore, another object of the present invention is to provide a superconducting motor cooling structure that is resistant to vibrations of the motor itself and external shocks and can stably operate the superconducting motor.

  The present invention achieves the above object by conducting and cooling a superconducting coil of a superconducting motor without using a fluid refrigerant and disposing the superconducting coil only on a stator.

  The present invention is a superconducting motor cooling structure having a rotor that rotates about an axis and a stator in which a superconducting coil that generates a magnetic field for rotating the rotor is disposed. The superconducting motor cooling structure includes a conduction cooling mechanism that cools the superconducting coil by conduction cooling, and the superconducting coil disposed in the stator of the superconducting motor is at least one of a field coil or an armature coil. It is characterized by.

  Hereinafter, the present invention will be described in more detail.

  The superconducting motor used in the cooling structure of the superconducting motor of the present invention is not particularly limited as long as it is a superconducting motor using a superconducting coil only for the stator. As such a superconducting motor, for example, a superconducting field coil may be arranged on the stator and a normal conducting armature coil may be arranged on the rotor, or a superconducting field magnet may be used as will be described later. Both the coil and the superconducting armature coil may be arranged on the stator and the rotor may be provided with an inductor. Whatever structure the motor is selected, a superconducting coil constructed using a superconducting material is cooled by conduction cooling.

  A conduction cooling mechanism for carrying out conduction cooling includes a refrigerator and a conduction cooling terminal connected to a cold head of the refrigerator (a part of the structure of the refrigerator that actually cools the target). The conduction cooling terminal is also connected to a superconducting coil disposed on the stator of the superconducting motor. At this time, by superposing the superconducting coil, the cold head of the refrigerator and the conduction cooling terminal in a vacuum, the structure of the superconducting motor can be simplified and the vacuum can be efficiently maintained. become.

  Among the conductive cooling mechanisms described above, an existing refrigerator can be used. As the refrigerator, for example, a GM refrigerator, a Stirling refrigerator, a pulse tube refrigerator, or the like can be suitably used.

  On the other hand, the conduction cooling terminal connected to the refrigerator is made of a material having high thermal conductivity such as aluminum and copper. The shape of the conduction cooling terminal may be appropriately selected in consideration of the positional relationship between the superconducting motor (superconducting coil) and the refrigerator and the margin of the arrangement space. Of course, the conductive cooling terminal may have a different shape or a different material, with the portion connected to the cold head of the refrigerator and the portion contacting the superconducting coil as separate members.

  Of the conduction cooling terminal, the shape of the portion that contacts the superconducting coil is preferably a shape that can increase the contact area with the superconducting coil. For example, it can be formed in a plate shape, a line shape, or a block shape. When the conductive cooling terminal is formed in a plate shape or a block shape, the conductive cooling terminal is easily arranged as will be described later. Here, when the conductive cooling terminal is formed in a plate shape or a block shape, when the coil disposed on the stator is an armature coil, the magnetic field generated by the armature coil is an alternating magnetic field. An eddy current is generated on the surface and heat is generated. Accordingly, the conduction cooling terminal used for conduction cooling of the armature coil is preferably formed in a shape that divides the current path of the eddy current, for example, in a linear shape. Note that, even when formed in a plate shape or a block shape, for example, a non-conductive material and a conductive material may be configured to be striped to suppress the generation of eddy currents.

  The method for connecting the above-described conduction cooling terminal to the superconducting coil is not particularly limited. For example, a plate-shaped conduction cooling terminal may be wound so as to cover the outer periphery of the superconducting coil, or a block-shaped conduction cooling terminal having a shape along the outer shape of the coil may be contacted along the outer shape of the coil. Absent. In addition, it is preferable to insert a plate-like, wire-like, or block-like conductive cooling terminal between the layers of the coil around which the conductive wire is wound, so that the contact area between the coil and the conductive cooling terminal can be increased. When inserting a conductive cooling terminal between the coil layers, if using a plate-like conductive cooling terminal, wrap the plate-shaped conductive cooling terminal so as to cover the surface of the layer with the coil. The next layer of the coil is formed on the conductive conduction cooling terminal. Moreover, if a linear thing is used for a conduction cooling terminal, for example, it winds with the pitch different from the pitch of the conducting wire which forms a coil, or arrange | positions a linear conduction cooling terminal in parallel with the coil winding axis | shaft. .

  As described above, by applying conduction cooling to the superconducting coil, it is not necessary to circulate the refrigerant inside the superconducting motor as in the conventional superconducting motor, so it is necessary to provide a highly airtight section for circulating the refrigerant. There is no. Therefore, in the cooling structure of the superconducting motor of the present invention, it is sufficient if there is only one section (vacuum holding section) for maintaining a vacuum for heat insulation as the section having high airtightness.

  The vacuum holding section only needs to be of a material and shape having such strength that it will not be damaged when the inside of the vacuum holding section is evacuated. Examples of the material for the vacuum holding compartment include alloys such as stainless steel.

  In addition, the vacuum holding section is not limited as to where it is provided as long as it can exhibit heat insulation performance that maintains the superconducting coil at a desired temperature. The vacuum holding section may be provided so as to cover at least the outer periphery of the superconducting coil. For example, all the superconducting coils existing inside the superconducting motor may be covered with the vacuum holding section. Whatever configuration is selected when providing the vacuum holding section, it is preferable that the superconducting coil, the conductive cooling terminal, and the cold head of the refrigerator be arranged in a vacuum. By the way, when all the superconducting coils existing inside the superconducting motor are arranged in a vacuum, the conductive cooling terminals connected to each superconducting coil are gathered together and connected to the cold head of the refrigerator. be able to. That is, all the superconducting coils in the superconducting motor can be cooled by one refrigerator. Moreover, since the alloy vacuum holding section can be moved away from the superconducting coil, eddy current loss can be reduced.

  In addition, it is preferable to arrange a heat insulating member (super insulation) for reflecting radiation rays inside the vacuum holding section. Here, although it has already been described that it is not necessary to provide double airtight compartments, a heat insulating material holding compartment for holding the above-described heat insulating material may be provided along the internal shape of the vacuum holding compartment. Since this heat insulating material holding section is provided to hold the heat insulating material, it does not need to be airtight and therefore does not correspond to a conventional refrigerant holding section.

By employing the configuration of the present invention, it is not necessary to use a refrigerant for cooling the superconducting coil, and it is only necessary to provide one highly airtight section for maintaining a vacuum. Accordingly, the following effects are obtained.
[1] Since the structure of the superconducting motor including the heat insulating structure becomes simple, the superconducting motor can be easily manufactured.
[2] A tank for storing the refrigerant and a pump for circulating the refrigerant need not be provided, and the superconducting motor including the cooling structure can be reduced in size and weight.
[3] Since the structure is less than that of the conventional cooling structure, maintenance opportunities can be reduced and maintenance is facilitated.
[4] Since there are fewer places to maintain airtightness, the possibility of breaking the seal can be reduced.
[5] Due to vibration when the superconducting motor is operated, the refrigerant does not vibrate, and problems such as a decrease in the circulation amount of the refrigerant do not occur.

<Example>
Hereinafter, an embodiment of the present invention will be described by taking as an example a cooling structure of a superconducting motor in which both a field coil and an armature coil are disposed as superconducting coils in a stator and an inductor is disposed in a rotor. First, an outline of the cooling structure of the superconducting motor and the connection relationship between the conduction cooling mechanism used in this cooling structure and the superconducting motor will be described. Next, superconductivity using a superconducting coil connected to the conduction cooling mechanism The motor will be described.

  FIG. 1 is a schematic explanatory view showing the cooling structure of the superconducting motor of this embodiment. The cooling structure of the superconducting motor of this example includes a superconducting motor 1 and a conduction cooling mechanism 2 (a refrigerator 20 and a conduction cooling terminal 21). In this conduction cooling mechanism 2, one end of the conduction cooling terminal 21 was connected to the cold head 20c of the refrigerator 20, and the other end was connected to the superconducting coil 3. As will be described later, the superconducting coil 3 includes a field coil and an armature coil, which are respectively fixed and arranged inside the superconducting motor 1. Further, the vacuum holding section 4 was formed so as to include the superconducting coil 3, the conductive cooling terminal 21, and the cold head 20c of the refrigerator 20, and the inside of the section 4 was evacuated.

  In this example, the conductive cooling terminal 21 is a set of a plurality of flat braided wires insulated from each other. One end side of the assembled flat braided wire was connected to the cold head of the refrigerator, and the other end side was branched and connected to each superconducting coil. The flat braided wire is flexible and has a high degree of freedom in wiring. Further, since this flat braided wire also has the effect of suppressing the generation of eddy currents, it is difficult to degrade the performance of the superconducting motor even in the vicinity of the location where the AC magnetic field is generated (specifically, the armature coil). . Therefore, by using a flat braided wire for the conduction cooling terminal 21, the conduction cooling terminal 21 is connected to the superconducting coil 3 so as not to obstruct the operation of the superconducting motor 1 inside the vacuum holding section 4 shown in FIG. can do.

  The connection between the conduction cooling terminal 21 in the form of a flat braided wire and the superconducting coil 3 is made by inserting this flat braided wire between the conductors of the superconducting coil 3, that is, between adjacent layers of the conductors wound in multiple layers. Performed. In the following, only the structure and forming process of the armature coil will be described as a specific example, but also in the field coil, the use of a flat braided wire as a conduction cooling terminal, and this flat braided wire is inserted between the layers of the coil. The thing is the same as the armature coil.

  FIG. 2 is a diagram showing a process of disposing a conductive cooling terminal (flat braided wire 210) on the superconducting coil 3 (an armature coil described later). First, the conductive wire 100 was wound around the coil winding drum to form the first layer c1 of the coil. Next, an assembly of flat braided wires extending from the cold head of the refrigerator is branched, and this branched flat braided wire 210 is substantially parallel to the axial direction of the coil winding drum on the first layer c1. Placed in multiple. The flat braided wires 210 were arranged uniformly at intervals in the circumferential direction so as to cover the entire first layer c1 of the coil. In FIG. 2, each flat braided wire 210 is shown with a constant length, but actually it extends continuously from the end of the flat braided wire 210 shown in the figure, and finally the cold braid of the refrigerator. Connected to the head. After arranging the flat braided wire 210 as described above, the conductive wire 100 was wound on the flat braided wire 210 to form the second layer c2 of the coil. The third and subsequent layers were also formed so that the flat braided wire 210 (conductive cooling terminal) was inserted between the coil layers as described above. Of course, a sufficient cooling effect can be obtained without inserting the flat braided wire 210 between all the layers, and there may be a layer in which the flat braided wire 210 is not inserted. Although not shown in FIG. 2, there is actually a magnetic body magnetized by the coil inside the cylindrical coil winding drum.

  A superconducting motor was created using the superconducting coil to which the conductive cooling terminal was connected as described above. The structure of the superconducting motor will be described below.

  FIG. 3 is a schematic configuration diagram showing a superconducting motor used in this example. The main part of this superconducting motor is configured by arranging the field side stator 11, the rotor 12, the armature side stator 13, the rotor 14, and the field side stator 15 in the rotation axis direction of the shaft 16. Of the main parts, the field side stators 11 and 15 are provided with one field 110 and 150, respectively, and the armature side stator 13 is provided with six armatures 130. In addition, eight inductors 120 and 140 are arranged on the rotors 12 and 14, respectively. The inductors 120 and 140 are attracted and repelled by the action of the magnetic fields generated by the field magnets 110 and 150 and the armature 130 to rotate the rotors 12 and 14. As the rotors 12 and 14 rotate, the rotational power is transmitted to the outside through the shaft 16 fixed to the rotors 12 and 14. Here, the field side stators 11 and 15 are the same member and are arranged to face each other. The rotors 12 and 14 are also the same member, and the arrangement of the inductors 120 and 140 shown in the drawing is different because the same member is viewed from another surface.

  Next, the structure and positional relationship of the field 110, the armature 130, and the inductor 120 will be described with reference to FIG. In FIG. 4, a part of the inductor 120 and the armature 130 is omitted.

  The field 110 is a cylindrical member configured such that a magnetic pole face (S pole face 111, N pole face 119) that generates a steady magnetic field is formed on the surface thereof. At the center of the cylinder, a rotation shaft hole 110h through which the shaft 16 serving as the rotation shaft of the superconducting motor can be passed is provided. Further, an annular groove coaxial with the rotation axis was formed in the field 110, and a field coil 110c was disposed in the circular groove. When a direct current is applied to the field coil 110c, the S pole surface 111 is formed on the surface where the field coil 110c is exposed on the radially inner side of the field coil 110c (the portion having the rotation shaft hole 110h). An N pole surface 119 is formed radially outward from the magnetic coil 110c.

  The armature 130 is a member disposed on the armature side stator 13 so as to generate an alternating magnetic field for attracting and repelling and rotating the inductor 120 disposed on the rotor 12. Specifically, in the armature-side stator 13, six armatures 130 (4 are omitted in FIG. 4) are arranged at equal intervals on the circumference concentric with the rotation shaft of the superconducting motor. An AC magnetic field is generated on the end face of the armature-side stator 13 (the face facing the end face of the rotor 12). The armature 130 is provided with a cylindrical iron core and a coil (armature coil 130c) formed by winding a conducting wire around the central portion of the side wall of the iron core. The magnetic pole changes. That is, an AC magnetic field can be generated on the end face of the armature side stator 13 by applying an AC current to the armature coil 130c. These armature coils 130c are not always energized, and are appropriately energized or the direction of current is changed so that the rotor 12 described later can be rotated. Specifically, the current flowing through the armature coil 130c is controlled so that the rotor 12 having the inductor 120, which will be described later, rotates in one direction. The pole portion 131 is formed. Further, the armature side stator 13 is provided with a rotation shaft hole (not shown) through which the shaft 16 which is the rotation shaft of the superconducting motor is penetrated similarly to the field 110.

  The rotor 12 was configured by embedding eight (not shown in FIG. 4, four are shown) iron bars (inductors 120) in a disc-shaped insulating member. At this time, the inductor was exposed at both end faces of the insulating member. The inductor 120 is magnetized by the S-pole surface 111 and the N-pole surface 119 of the field 110 described above, and has a constant magnetic field. The inductor 120 is attracted and repelled by the alternating magnetic field generated by the armature coil 130 described above. Since the inductor 120 is fixed and arranged on the insulating member of the rotor 12, the rotor 12 rotates as a result of the suction and repulsion of the inductor 120. Here, the inductor 120 is arranged so as to be inclined with respect to the rotation axis, and the arrangement of the inductor 120 exposed on the surface of the rotor 12 is a surface facing the field 110 and a surface facing the armature 130. And made it different. Specifically, the end face of each inductor 120 facing the armature 130 is disposed so as to coincide with the circumference where the armature 130 is disposed. On the other hand, the end faces of the inductor 120 facing the field 110 are alternately arranged so as to coincide with the N pole face 119 and the S pole face 111 of the field 110. By doing so, the inductor 120 is magnetized by the field 110, and the N-pole inductor 129 and the S-pole inductor 121 are alternately arranged in the circumferential direction. As a result, the inductor 120 is attracted and repelled by the N pole portion 139 and the S pole portion 131 of the armature 130 adjacent to the inductor 120, so that the rotor 12 in which the inductor 120 is disposed has the shaft 16 Rotate to center.

  Of the superconducting motor configuration shown in FIG. 3, if there are three of the field side stator 11, the rotor 12, and the armature side stator 13, the motor functions. However, as shown in this example, the motor output can be increased by adding the rotor 14 and the field-side stator 15. Of course, a field side stator / rotor / armature side stator may be further added in the axial direction of the shaft 16.

  As described above, by applying the conduction cooling mechanism to the superconducting coil, a small and light superconducting motor could be manufactured. Note that the conduction cooling mechanism of the present invention can also be applied to a superconducting motor in which either a field coil or an armature coil is disposed on a stator.

  The present invention can be suitably used for a superconducting motor that needs to be reduced in size and weight. In particular, the present invention can be suitably used for electric vehicles, ship screws, and the like that are required to be small and light and easy to maintain.

FIG. 1 is a schematic configuration diagram illustrating a positional relationship between the superconducting motor and the conduction cooling mechanism described in the embodiment. FIG. 2 is a diagram illustrating a positional relationship between the armature coil and the conduction cooling terminal described in the embodiment. FIG. 3 is a schematic configuration diagram of the superconducting motor described in the embodiment. FIG. 4 is a schematic configuration diagram illustrating a relationship among a field, an armature, and an inductor of the superconducting motor described in the embodiment.

Explanation of symbols

1 Superconducting motor 2 Conductive cooling mechanism 3 Superconducting coil
4 Vacuum holding compartment 16 Shaft
100 Lead wire c1 Coil first layer c2 Coil second layer
210 Flat braided wire (conduction cooling terminal)
20 Refrigerator 20c Cold head 21 Conduction cooling terminal
11,15 Field side stator 13 Armature side stator
12,14 Rotor 120,140 Inductor
110,150 Field 110c Field coil 111 S pole face 119 N pole face
121 S pole inductor 129 N pole inductor 110h Rotating shaft hole
130 Armature 130c Armature coil 131 S pole 139 N pole

Claims (6)

A superconducting motor cooling structure having a rotor that rotates about a rotation axis and a stator in which a superconducting coil that generates a magnetic field for rotating the rotor is disposed,
With a conduction cooling mechanism that cools the superconducting coil by conduction cooling,
A superconducting motor cooling structure, wherein the superconducting coil is at least one of a field coil and an armature coil.   The superconducting motor cooling structure according to claim 1, wherein the conduction cooling mechanism includes a refrigerator having a cold head and a conduction cooling terminal connected to the cold head to conduct and cool the superconducting coil.   3. The superconducting motor cooling structure according to claim 2, wherein at least the superconducting coil, the conduction cooling terminal, and the cold head are held in a vacuum.   4. The superconducting motor cooling structure according to claim 2, wherein a part of the conduction cooling terminal is inserted between the conductors of the superconducting coil.   The cooling structure for a superconducting motor according to claim 2, wherein at least a part of the conduction cooling terminal is a braided wire.   6. The superconducting motor cooling structure according to claim 1, wherein a field coil and an armature coil are disposed on the stator, and an inductor is disposed on the rotor.

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