| 摘要 |
PROBLEM TO BE SOLVED: To absorb the thermal extension of a retaining ring for preventing the oscillation of a rotating rotor from changing suddenly and being bent by heat and a permanent magnet from being peeled off, by fixing the retaining ring disposed on the surface of the permanent magnet on a shaft at a plurality of points in an axial direction, and forming a supporting structure having elasticity in the axial direction at one of the points disposed on one side in the axial direction. SOLUTION: End rings 4a, 5 clamp a permanent magnet 3 in an axial direction and are shirinkingly fitted to a shaft 1 so that a prescribed narrow space may be left to the paramount magnet 3. The end ring 4a is formed so that thickness in the axial direction may become thin to decrease axial rigidity thereof and have elasticity in the axial direction. In the meantime, the end ring 5 has high rigidity in the axial and radial directions. A retaining ring 6 is fitted and fixed on the outer peripheral surfaces of the end rings 4a, 5. When a rotor 7A is rotated at high speed, the end ring 4a elastically deforms and absorbs windage loss generated on the outer-peripheral surface of the retaining ring 6 and the thermal elongation of the retaining ring 6 due to a temperature rise caused by eddy current or the like.
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