| 摘要 |
In a thrust dynamic-pressure bearing that through pump-in type spiral grooves generates dynamic pressure, a simple configuration to eliminate at the bearing exterior air bubbles liable to build up nearby the central portion of the bearing, yielding stabilized axial bearing force. The configuration lends superior endurance and reliability to the thrust bearing, and to a spindle motor furnished with the bearing. The configuration makes the circularly symmetrical dynamic pressure distribution, created by spiral grooves formed circularly symmetrical with respect to the bearing axial center, asymmetrical by the addition of an asymmetrical auxiliary groove(s). Air bubbles building up near the center of the spiral grooves are thus shifted to the area where the spiral grooves are formed. In the area where the spiral grooves are formed, the more inward the oil the higher the dynamic pressure. Therefore, because air bubbles will tend to shift from a region of high to a region of low oil pressure, the air bubbles get pushed out to the outer circumferential margin of the spiral grooves.
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