| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small cored motor which is thin and less expensive and whose long life can be obtained by providing a ball bearing whose balls are held by two tapered parts and a shaft. SOLUTION: A bearing housing 14 is formed in such a way that its diameter becomes stepwise smaller from both end parts. The surface inner circumference of a first annular ball holder 18, whose bottom face is supported by a first doughnut-shaped leaf spring 17 and which is housed so as to be capable of being slid in the second step hole 14b of the bearing housing 14, is formed to be a conical taper 18a. Consequently, since the bottom face of the first ball holder 18 is energized by the doughnut-shaped leaf spring 17, the first ball holder 18 is slid moderately in the second step hole 14b, balls 19 are pressed to a shaft 10 in cooperation with a taper part 14c, and the balls are positioned and held in three points. In the same manner, a second ball holder 22 presses balls 21 to the shaft 10 in cooperation with a free-end-side taper part 14h, and they are positioned and held in three points. As a result, it is possible to obtain this small cored motor which is thin and low-cost, whose shaft runout is not generated even in a high-speed rotation and whose long life is obtained.
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