| 摘要 |
PROBLEM TO BE SOLVED: To maintain the rotation property of a motor by preventing the pre- load given to a bearing from being ineffective even in case that thermal expansion arises in each member constituting the motor at high temperature of the motor, in a spindle motor for driving a recording disk equipped with a ball bearing using a ball made of ceramic. SOLUTION: In a spindle motor for driving a recording disk where a pair of ball bearings 6 and 8 where a plurality of ball bearings 6c and 8c made of ceramic are interposed between inner rings 6a and 8c and outer rings 8b and 8b are arranged apart in axial direction between a rotor hub 10 and a shaft 4, at least one axial end face each of the inner rings 6a and 8a abuts on the axial end of a circular member such as the outward projection 4a or the like of the shaft 4 larger in thermal expansion coefficient than the shaft 4 and the rotor hub 10, and the inner projection 4a thermally expands at high temperature of the motor, and the inner ring 6a and/or 8a abutting on this is pressed in axial direction, whereby the axial space between the inner rings 6a and 8a of the ball bearings 6 and 8 is adjusted, which prevents pre-load from being ineffective. |
