FLUID DYNAMIC-PRESSURE BEARING MECHANISM, MOTOR AND RECORDING-DISK DRIVING DEVICE

摘要

PROBLEM TO BE SOLVED: To stably circulate lubricating oil in a fluid dynamic-pressure bearing mechanism.;SOLUTION: Internal flow paths and openings are filled with lubricating oil in a bearing mechanism 2. Lubricating oil is held by a first tapered sealing section 271 formed on the outer periphery of a sleeve 21 and a second tapered sealing section 272 formed between an upper cap 25 fitted to the upper section of the sleeve 21 and a shaft 22. The flow-path sectional areas of flow paths 266 and 267 connecting the first tapered sealing section 271 and the second tapered sealing section 272 are expanded between the upper cap 25 and the sleeve 21 by the groove-shaped recessed section of the internal side face of the upper cap 25 and the projecting section of the underside of an upper section. Accordingly, the flow-path resistances of the flow paths 266 and 267 are made smaller than the flow path 265 connecting a thrust opening 262 and the first tapered sealing section 271, and the leakage of lubricating oil is prevented in the first tapered sealing section 271. An interface is thereby lowered by the second tapered sealing section 272, and the mixing of bubbles is prevented.;COPYRIGHT: (C)2009,JPO&INPIT