| 摘要 |
PROBLEM TO BE SOLVED: To enhance reliability during operation by fitting a holding ring over a shaft at one axial position thereby preventing thermal elongation or bend of the holding ring. SOLUTION: A holding ring 6 is fitted over a shaft 1 only at one position of a protrusion 6a on the inner diameter side and it can thermally elongate freely to the left and right from the fitting part when the gaps between the shaft 1, a permanent magnet 3, end rings 4, 5 and the holding ring 6 are not filled with an elastic member 8. Even when each gap is filled with the elastic member 8, the holding ring 6 can thermally elongate freely to the left and right from the fitting pant through elastic deformation of the elastic member 8. Since abrupt change in the oscillation or thermal bend of a rotor 7A due to thermal elongation of the elastic member 8 is eliminated, the rotor 7A can be rotated stably at high speed while preventing it from being damaged or scattered.
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