JP2011041403A - Rotor core and cooling method of the rotor core, and superconductive rotating machine equipped with the rotor core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor core which efficiently and uniformly cools an superconductive coil without causing low-temperature brittleness even in an extremely low temperature zone, a cooling method of the rotor core, and a superconductive rotating machine equipped with these constitutions. <P>SOLUTION: The rotor core RC is constituted of a substantially-hollow cylindrical body of a non-magnetic material having an annular space which penetrates in the axial direction. The rotor core is cooled by a helium gas flowing toward a terminal end side from a base end side of the rotor core RC, and a helium gas flowing toward the base end side from the terminal end side of the rotor core RC. In other words, since the helium gases being refrigerants are fed to opposing directions from the base end side and the terminal end side of the rotor core RC, the lengthy rotor core RC extending in the axial direction is uniformly cooled. By this, the superconductive coil is efficiently and uniformly cooled. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a structure of a rotor core of a superconducting rotating machine, a method for cooling the rotor core, and a superconducting rotating machine including the rotor core.

  In general, a superconducting rotating machine includes a stator and a rotor that are electromagnetically coupled. The rotor includes a multipolar rotor core and one or more field coil windings attached to the rotor core. The rotor core is made of a magnetically permeable solid member extending in the direction of the rotation axis, and is usually made of a ferromagnetic material such as iron (see, for example, Patent Document 1).

  On the other hand, in order to keep the superconducting coil attached to the rotor core in a superconducting state, the superconducting coil is cooled to about 30K by conduction cooling, for example. The cooling technology for this superconducting coil (rotor core) is generated by immersing the superconducting coil in a refrigerant such as liquid helium or liquid nitrogen and cooling it, or by bringing the cold head of the refrigerator into contact with the superconducting coil. A technique for cooling the superconducting coil by solid-state heat conduction using the amount of cold heat thus produced is known (for example, see Patent Documents 2 to 4).

JP 2003-125573 A JP-A-6-302869 Japanese Patent Laid-Open No. 10-9696 JP 2003-151822 A

  In the rotor core disclosed in Patent Document 1, since it is a heavy object formed of a solid member, it has a large heat capacity, and it takes time to uniformly cool the entire rotor core to a predetermined temperature. In addition, when a superconducting coil is used as an electromagnet, the generated magnetic field is high, and a magnetic material such as iron is saturated and cannot be used. Furthermore, as described above, in order to keep the superconducting coil in the superconducting state, it is necessary to cool the superconducting coil to, for example, about 30K. However, when carbon steel such as iron is used in an extremely low temperature range of 30K, the temperature is low. Since brittleness occurs, to avoid this, it is necessary to form the rotor core with a material that does not cause low-temperature brittleness.

  Further, the superconducting coil (rotor core) cooling technology disclosed in Patent Documents 2 to 4 has the following problems. That is, in the technology of immersing and cooling a superconducting coil in a refrigerant such as liquid helium or liquid nitrogen, the superconducting coil is cooled by sending a cryogenic refrigerant (liquid helium or liquid nitrogen) into the coil holding container. Therefore, various facilities for handling cryogenic refrigerants and special care are required, which is not only disadvantageous in terms of equipment space, equipment cost and handling, but also it is difficult to adjust the cooling temperature range There were difficulties.

  In the technology of cooling the superconducting coil by solid heat conduction by bringing the cold head of the refrigerator into contact with the superconducting coil, the rotor core is a rotating body. Therefore, when the refrigerator is attached to the rotor core, the refrigerator rotates together with the rotor core. Will be. In this case, there is a problem that a torque for rotating the refrigerator is required, and a large space for rotating the refrigerator is required. In addition, in order to continuously supply, for example, high-pressure helium gas which is a cold heat source, it is necessary to provide a rotating seal mechanism in the rotating refrigerator. However, in practice, it is difficult to obtain a rotating seal mechanism with excellent sealing performance, and thus a cooling technique for bringing a cold head of a refrigerator into contact with a superconducting coil is not realistic.

  Therefore, the present invention has been made to solve the above-mentioned problems, and the object is to efficiently and uniformly superconducting coils without causing low temperature brittleness even in an extremely low temperature range. It is an object of the present invention to provide a rotor core that can be cooled, a method for cooling the rotor core, and a superconducting rotating machine that includes these configurations.

  A rotor core of a superconducting rotating machine according to the present invention is a rotor core of a superconducting rotating machine, and is composed of a substantially hollow cylindrical body of a nonmagnetic material having a cylindrical space penetrating in the axial direction in the rotor core of the superconducting rotating machine. The outer peripheral surface has a plurality of recesses for placing the superconducting coil, and at least two or more refrigerant passages penetrating from the proximal end side to the distal end side of the hollow cylindrical body are formed in the vicinity of the outer peripheral portion of the cylindrical space.

  A solid member extending in the axial direction coaxially with the refrigerant passage may be provided in the refrigerant passage with a predetermined space.

  It is preferable that a convex portion for forming a turbulent flow of the refrigerant distributed in the circumferential direction is formed on the inner wall surface of the refrigerant passage or the outer peripheral surface portion of the solid member.

  The cooling method in the rotor core of the superconducting rotating machine according to the present invention is the cooling method in the rotor core of the superconducting rotating machine according to any one of claims 1 to 3, wherein the base side of one refrigerant passage of the rotor coil The refrigerant is supplied from the terminal side to the terminal side, and the refrigerant is supplied from the terminal side of the other refrigerant passage of the rotor coil to the base side.

  The superconducting rotating machine according to the present invention includes a rotor core of the superconducting rotating machine according to any one of claims 1 to 3, wherein the rotor core includes an electromagnetically coupled stator and rotor.

  According to the rotor core of the superconducting rotating machine according to the present invention, it is composed of a substantially hollow cylindrical body of a non-magnetic material (for example, austenitic stainless steel such as SUS316), so that it is lightweight and has an extremely low value of, for example, 30K. It is possible to provide a rotor core of a superconducting rotating machine excellent in strength without causing low-temperature brittleness even in a temperature range.

  Further, according to the cooling method in the rotor core of the superconducting rotating machine according to the present invention, since the refrigerant is supplied in the direction facing the base end side and the terminal end side of the rotor core, the long rotor core extending in the axial direction Can be cooled uniformly. Further, a solid member extending in the axial direction coaxially with the refrigerant passage in the refrigerant passage is internally provided with a predetermined space, and is provided on the outer peripheral surface portion of the solid member facing the inner wall surface of the refrigerant passage or the inner wall surface of the refrigerant passage. The heat exchange efficiency is further improved by forming the recess that forms the turbulent flow of the refrigerant. As a result, there is an effect that the superconducting coil can be efficiently and uniformly cooled.

It is the schematic block diagram which showed the whole system of the superconducting motor. It is the perspective view which showed typically the structure of the rotor core which concerns on embodiment of this invention. It is a perspective view which shows the state which mounted | wore with the racetrack type superconducting coil in the rotor core. It is the perspective view which showed the flow direction (a supply path | route and a return path | route) of the refrigerant | coolant of the rotor core which concerns on embodiment of this invention. It is the cross-sectional view which showed the detailed structure of the refrigerant path arrange | positioned in the rotor coil.

  Hereinafter, a rotor core according to the present invention, a cooling method of the rotor core, and a superconducting rotating machine including the rotor core will be described with reference to the accompanying drawings. In the following description, terms including “base end”, “terminal end”, and terms thereof are used for the sake of convenience, but these terms are for facilitating understanding of the invention, and the terms are within the technical scope of the present invention. Should not be interpreted in a limited way.

  In this specification, the position of each component of the rotor core is defined as “base end (side)” on the refrigerant supply / discharge device side, and “terminal (side)” on the output shaft side of the superconducting motor.

  FIG. 1 is a schematic configuration diagram showing an entire system of a superconducting motor, FIG. 2 is a perspective view schematically showing the structure of a rotor core according to an embodiment of the present invention, and FIG. 3 is a race track on the rotor core. It is a perspective view which shows the state which mounted | wore the type | mold superconducting coil. 4 is a perspective view showing the flow direction (supply path and return path) of the refrigerant in the rotor core according to the embodiment of the present invention, and FIG. 5 is a view of the refrigerant path arranged in the rotor coil. It is the cross-sectional view which showed the detailed structure.

1. Configuration of Rotor Core As shown in FIG. 1, the rotor core RC of the present embodiment is incorporated in a superconducting motor. Then, the entire rotor core RC is cooled by a refrigerant such as helium gas supplied from the refrigerant supply / discharge device (hereinafter, described as “helium gas” in the present embodiment), and the rotor core is cooled by conduction cooling. The superconducting coil attached to the RC is cooled to, for example, about 30K and held in the superconducting state.

  As described in [Summary of Invention], the material of the rotor core RC of the present embodiment is as follows: (1) When a superconducting coil is used as an electromagnet, the magnetic field generated is high, and the magnetic field is saturated in a magnetic material such as iron. . (2) When carbon steel is used in an extremely low temperature range of 30K, for example, low temperature brittleness occurs. For these reasons, for example, SUS316, which is a non-magnetic material and has excellent low-temperature characteristics, is used.

  Since this rotor core RC needs to be incorporated into a superconducting motor to transmit a large torque, a solid cylindrical forging material made of SUS316 is cut into a substantially hollow cylindrical body. By forming the rotor core RC into a substantially hollow cylindrical body, the weight of the rotor core RC main body can be reduced. Further, since the weight can be reduced, the heat capacity can be reduced as compared with the conventional rotor core.

  As shown in FIG. 2, the rotor core RC has flange portions 10 and 11 on the proximal end side and the distal end side, and a cylindrical space 20 penetrating in the direction of the central axis 100 is formed. Further, in the vicinity of the outer peripheral portion of the cylindrical space 20, refrigerant passages 30a, 30b and 40a, 40b penetrating from the proximal end side to the distal end side of the rotor core RC are spaced by 90 degrees in the circumferential direction of the cylindrical space 20. Open and formed. Further, a refrigerant supply pipe 50 and a refrigerant return pipe 51 are inserted into the cylindrical space 20 from the base end side to the terminal end side of the rotor core RC. The helium gas flow direction (supply path and return path) in which helium gas supplied from the refrigerant supply pipe 50 is returned to the refrigerant return pipe 51 via the refrigerant passages 30a, 30b and 40a, 40b is shown in FIG. Will be described in detail with reference to FIG.

  As shown in FIG. 4, the refrigerant supply pipe 50 is branched into a supply pipe 530 and a supply pipe 540. The supply pipe 530 branches to the refrigerant inlet pipes 530a and 530b by the joint 55a on the refrigerant supply / discharge device side, that is, the base end side of the rotor core RC. The refrigerant inlet pipe 530a is connected to the proximal end side of the refrigerant passage 30a, and the refrigerant inlet pipe 530b is connected to the proximal end side of the refrigerant passage 30b.

  A refrigerant outlet pipe 531a is connected to the end side of the refrigerant passage 30a, and a refrigerant outlet pipe 531b is connected to the end side of the refrigerant passage 30b. The refrigerant outlet pipe 531a and the refrigerant outlet pipe 531b are assembled by a joint 55b on the motor output shaft side, that is, on the terminal side of the rotor core RC, and are connected to a return pipe 531 penetrating through the cylindrical space 20 of the rotor core RC. .

  On the other hand, the supply pipe 540 is provided penetrating through the cylindrical space 20 of the rotor core RC, and branches to the refrigerant inlet pipes 540a and 540b by the joint 56a on the motor output shaft side, that is, on the terminal end side of the rotor core RC. The refrigerant inlet pipe 540a is connected to the end side of the refrigerant passage 40a, and the refrigerant inlet pipe 540b is connected to the end side of the refrigerant passage 40b.

  A refrigerant outlet pipe 541a is connected to the base end side of the refrigerant passage 40a, and a refrigerant outlet pipe 541b is connected to the base end side of the refrigerant passage 40b. The refrigerant outlet pipe 541a and the refrigerant outlet pipe 541b are assembled by a joint 56b on the refrigerant supply / discharge device side, that is, the base end side of the rotor core RC, and are connected to the return pipe 541. The return pipe 531 and the return pipe 541 serve as the refrigerant return pipe 51 that merges at a predetermined position on the proximal end side of the rotor core RC.

  Thus, the refrigerant passages 30a and 30b facing the rotor core RC form a pair of refrigerant passages in which the helium gas supply direction flows from the refrigerant supply device side to the motor output shaft side (from the base end side to the terminal end side of the rotor core RC). The refrigerant passages 40a and 40b facing each other form a pair of refrigerant passages in which the supply direction of the helium gas flows from the motor output shaft side to the refrigerant supply device side (from the terminal end side to the base end side of the rotor core RC).

  That is, the rotor core RC of the present embodiment includes a helium gas passage supplied to the rotor core RC that branches radially at the proximal end side of the rotor core RC and flows to the distal end side of the rotor core RC, The outer periphery of the cylindrical space 20 of the rotor core RC is formed so as to pass through the cylindrical space 20 and alternately branch into the radial direction at the distal end side of the rotor core RC and flow to the proximal end side of the rotor core RC. A plurality of parts are arranged in the part. In other words, since helium gas, which is a refrigerant, is supplied in a direction facing the base end side and the terminal end side of the rotor core RC, the long rotor core RC extending in the axial direction can be uniformly cooled.

  In the present embodiment, the four refrigerant passages 30a, 30b, 40a, 40b are arranged in the outer peripheral portion of the cylindrical space 20 of the rotor core RC. However, the present invention is not limited to this, and six or eight are provided. Two refrigerant passages may be formed.

  Next, the internal structure of the refrigerant passages 30a, 30b, 40a, 40b will be described with reference to FIG. 5 (note that FIG. 5 shows the internal structure of the refrigerant passages 30a, 30b, and the refrigerant passages 40a, 40b The flow direction of the helium gas G is opposite to that in the figure).

  As shown in FIG. 5, a solid cylindrical core 90 extending in the axial direction coaxially with the refrigerant passage 30a (30b) is provided inside the refrigerant passage 30a (30b) with a predetermined space. Yes. A plurality of ring-shaped convex portions 95 are formed on the outer peripheral portion of the core 90 at equal pitches in the axial direction. The core 90 is not limited to a solid cylinder, but may be a hollow cylinder obtained by processing a pipe-like member.

  The reason why a plurality of ring-shaped convex portions 95 are formed on the outer peripheral portion of the core 90 is that when the helium gas G flows in the refrigerant passage 30a (30b) and there is no ring-shaped convex portion 95, the refrigerant passage 30a. This is because a boundary layer is formed on the inner wall surface of (30b), and this boundary layer hinders heat transfer and lowers heat exchange efficiency. With such a configuration, the formation of the boundary layer on the inner wall surface of the refrigerant passage 30a (30b) is suppressed, and the generation of turbulent flow is promoted so that the main flow of helium gas G, which is the refrigerant, flows into the refrigerant passage 30a (30b). Heat exchange efficiency can be improved by contacting the wall surface.

  In the present embodiment, as one method for improving the heat exchange efficiency, a plurality of ring-shaped convex portions 95 are formed at an equal pitch in the axial direction on the outer peripheral portion of the core 90. For example, a plate member may be attached to the outer peripheral portion of the core 90 in a spiral shape, or many random recesses may be formed in the outer peripheral portion of the core 90. Further, for example, protrusions distributed over the entire circumferential surface of the inner wall surface of the refrigerant passage may be formed, and various modifications are possible as long as the above-described boundary layer formation is suppressed.

  Returning to FIG. 2, four notches 60 are formed in the radial direction of the flange portion 11 of the rotor core RC. A coil mounting recess 70 for placing a racetrack superconducting coil is formed on the outer periphery of the rotor core RC corresponding to each notch 60, and each coil mounting recess 70 is isolated by a rib 80. ing.

  By placing the superconducting coil on the bottom 71 of the coil mounting recess 70, the state shown in FIG. 3 is obtained. Thereby, the cold heat of the helium gas flowing through the refrigerant passages 30a, 30b, 40a, 40b is conducted from the entire rotor core RC including the bottom 71, and the superconducting coil can be cooled to a predetermined temperature.

2. Cooling operation of the rotor core Next, the cooling operation of the rotor core RC having the above structure, FIGS. 2, 3, 4 and 5 (mainly 4, 5) will be described with reference to. First, for example, helium gas cooled to a predetermined temperature by a two-stage refrigerator is supplied to the refrigerant supply pipe 50 via a refrigerant supply / discharge device (both not shown). As shown in FIG. 4, the helium gas supplied to the refrigerant supply pipe 50 penetrates the supply pipe 530 branched at a predetermined position on the base end side of the rotor core RC and the cylindrical space 20 of the rotor core RC. And is supplied to a supply pipe 540 arranged in a line.

  The helium gas flowing through the supply pipe 530 branches on the proximal end side of the rotor core RC, is divided into refrigerant inlet pipes 530a and 530b extending in the radial direction, and flows into the interior from the refrigerant passages 30a and 30b. As shown in FIG. 5, the helium gas G flowing into the refrigerant passages 30a and 30b collides with a plurality of convex portions 95 of the core 90 disposed in the refrigerant passages 30a and 30b. As a result, the formation of the boundary layer on the inner wall surface of the refrigerant passages 30a and 30b is suppressed, and the generation of turbulent flow is promoted. Thereby, the main flow of helium gas G which is a refrigerant can be brought into contact with the inner wall surfaces of the refrigerant passages 30a and 30b, and the rotor core RC main body can be efficiently cooled.

  The helium gas G exchanged in the refrigerant passages 30a and 30b is discharged from the refrigerant passages 30a and 30b, and gathers on the rotor core end via the refrigerant outlet pipe 531a and the refrigerant outlet pipe 531b. The refrigerant is returned to the refrigerant return pipe 51 through a return pipe 531 penetrating the inside of the cylindrical space 20.

  On the other hand, the helium gas flowing through the supply pipe 540 branches on the terminal side of the rotor core RC, is divided into refrigerant inlet pipes 540a and 540b extending in the radial direction, and flows into the inside from the terminal side of the refrigerant passages 40a and 40b. The helium gas G that has flowed into the refrigerant passages 40a and 40b efficiently cools the rotor core RC main body by the same action as described above.

  The helium gas G exchanged in the refrigerant passages 40a and 40b is discharged from the base end side of the refrigerant passages 40a and 40b, and gathers on the base end side of the rotor core via the refrigerant outlet pipe 541a and the refrigerant outlet pipe 541b. Returned to the return pipe 51.

  As described above, the rotor core RC of the present embodiment is cooled by the helium gas flowing from the base end side to the terminal end side of the rotor core RC and the helium gas flowing from the terminal end side of the rotor core RC toward the base end side. The That is, since helium gas, which is a refrigerant, is supplied in a direction facing the base end side and the terminal end side of the rotor core RC, the long rotor core RC extending in the axial direction can be uniformly cooled.

  As a result, the cooling heat of the helium gas flowing through the refrigerant passages 30a, 30b and 40a, 40b is conducted from the entire rotor coil RC including the bottom 71 to the superconducting coil placed on the bottom 71 of the coil mounting recess 70, and the superconducting coil Can be cooled to a predetermined temperature uniformly and efficiently.

  The embodiment disclosed this time is an example, and the present invention is not limited to this. The present invention is defined by the scope of the claims rather than the scope described above, and all modifications that are equivalent in meaning and scope to the claims are intended.

DESCRIPTION OF SYMBOLS 10 Flange part 11 Flange part 20 Cylindrical space 30a, 30b Refrigerant passage 40a, 40b Refrigerant passage 50 Refrigerant supply pipe 51 Refrigerant return pipe 60 Notch 70 Coil mounting recessed part 71 Bottom part 80 Rib 90 Core 95 Protrusion part 100 Center axis RC Rotor core

Claims (5)

In the rotor core of a superconducting rotating machine,
It consists of a substantially hollow cylindrical body of a non-magnetic material having a cylindrical space penetrating in the axial direction,
It has a plurality of recesses for placing a superconducting coil on the outer peripheral surface of the hollow cylindrical body,
A rotor core of a superconducting rotating machine, wherein at least two or more refrigerant passages penetrating from a proximal end side to a distal end side of the hollow cylindrical body are formed in the vicinity of an outer peripheral portion of the cylindrical space.   2. The rotor core of a superconducting rotating machine according to claim 1, wherein a solid member extending in the axial direction coaxially with the refrigerant passage is provided in the refrigerant passage with a predetermined space.   The convex part which forms the flow of the refrigerant | coolant distributed in the circumferential direction into a turbulent flow is formed in the inner wall surface of the said refrigerant path, or the outer peripheral surface part of the said solid member. Item 3. The rotor core of the superconducting rotating machine according to Item 2. A method for cooling a rotor core of a superconducting rotating machine according to any one of claims 1 to 3,
Supplying the refrigerant from the base end side to the terminal end side of one refrigerant passage of the rotor coil;
A cooling method for a rotor core of a superconducting rotating machine, wherein the coolant is supplied from the distal end side to the proximal end side of another refrigerant passage of the rotor coil.   A superconducting rotating machine including a stator and a rotor that are electromagnetically coupled to each other, wherein the rotor core of the superconducting rotating machine according to any one of claims 1 to 3 is provided.