| 摘要 |
PROBLEM TO BE SOLVED: To substantially stabilize bearing rigidity over a wide temperature range with a simple structure, in a liquid dynamic pressure bearing having at least a shaft member, a sleeve member receiving the shaft member, and lubricating oil charged in minute clearances including bearing clearance, and a spindle motor having the same. SOLUTION: A cylindrical member 2a made of material of large linear expansion coefficient is externally fitted to a lower side of a flanged shaft member 1 as a shaft member. A radial dynamic pressure generation groove is formed on an outer peripheral surface of the cylindrical member 2a. A cylindrical member 4a made of material of large linear expansion coefficient is internally fitted to a small diameter cylindrical part on a lower side of a stepped cylindrical sleeve member 4. With such a setup, range of automatic adjustment is increased in respect to clearance of the bearings according to temperature variation. It is thus possible to compensate variation of bearing rigidity due to viscous coefficient of lubricating oil by the variation of the bearing rigidity due to bearing clearance for a wide temperature range.
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