| 摘要 |
To prevent air from being trapped inside a bearing and causing the bearing to have oil film rupture and NRRO to deteriorate. In a hydrodynamic bearing, a first lubricant reservoir is provided in a gap between a lower surface of a hub and a sleeve, and a second lubricant reservoir is provided in a gap between an outer peripheral surface of the sleeve and an inner peripheral surface of the hub or an inner peripheral surface of a stopper member fixed to the hub. If air enters inside such a hydrodynamic bearing, the air has to be discharged. For this purpose, the relationship in widths of the radial bearing gap, the maximum gap of the first lubricant reservoir under the lower surface of the hub and the maximum gap of the second lubricant reservoir on the sleeve outer peripheral surface, or the relationship in magnitudes of capillary forces thereof is adjusted. The principle that air tends to move toward the portion having smaller capillary pressure is utilized to make it difficult for the air to be trapped inside the bearing and to smoothly discharge the air from a gas-liquid interface of the second lubricant reservoir.
|
