Cooling structure of superconducting motor
In a cooling structure of a superconducting motor in which a superconducting coil is attached to a rotor, grooves are concavely provided on an outer surface of a rotating shaft that penetrates and is fixed to the rotor. A refrigerant is circulated through a refrigerant circulation pipe disposed inside the grooves to that the superconducting coil is cooled by the refrigerant.
1. A cooling structure of a superconducting motor having a superconducting coil attached to a rotor, the cooling structure comprising:
a rotating shaft penetrating through and fixed to the rotor; and
a refrigerant circulation tube through which a refrigerant for cooling the superconducting coil circulates,
wherein a groove is formed on an outer surface of the rotating shaft, and the refrigerant circulation tube is disposed inside the groove,
wherein the refrigerant circulation tube includes:
a first pipe having a first outgoing path section and a first returning path section that are coupled to a supply source of the refrigerant for cooling the superconducting coil;
a second pipe having a second outgoing path section communicated with the first outgoing path section of the first pipe and a second returning path section communicated with the first returning path section of the first pipe, wherein the second pipe is fixed to an axial end of the rotating shaft and is rotatably coupled to the first pipe; and
a refrigerant circulation pipe having a third outgoing path section communicated with the second outgoing path section of the second pipe and a third returning path section communicated with the second returning path section of the second pipe.
2. The cooling structure of the superconducting motor according to claim 1 , wherein the groove includes a first longitudinal groove section, a second longitudinal groove section, and a coupling groove section,
the first longitudinal groove section and the second longitudinal groove section are formed along an axial direction of the rotating shaft at symmetric positions with respect to an axis of the rotating shaft, and
the coupling groove section is formed along a circumferential surface of the rotating shaft at a front end position of the rotor,
wherein the refrigerant circulation pipe further has a turnaround section which is disposed inside the coupling groove section and couples the third outgoing path section and the third returning path section.
3. The cooling structure of the superconducting motor according to claim 1 , wherein circumferential surfaces of the first pipe and the second pipe are surrounded by heat-insulating means.
4. The cooling structure of the superconducting motor according to claim 3 , wherein the heat insulating means includes an outer tube surrounding the first pipe and the second pipe, the outer tube providing a vacuum heat-insulation.
5. The cooling structure of the superconducting motor according to claim 1 , further comprising a first flange projected from a coupling end of the first pipe and a second flange projected from a coupling end of the second pipe, the first and the second flanges being rotatably in contact with each other; and
spring means for biasing the first and the second flanges in respective contacting directions.
6. The cooling structure of the superconducting motor according to claim 1 , wherein the refrigerant includes liquid nitrogen, neon, or helium.
7. The cooling structure of the superconducting motor according to claim 1 , wherein the superconducting motor is of an axial type or a radial type.