| 摘要 |
PROBLEM TO BE SOLVED: To suppress precession generated between a shaft and a sleeve rotating relative to one another, without increasing the size of a dynamic pressure fluid bearing.SOLUTION: A conical supporting protrusion 18 is formed in the center of the bottom face of a truncated cone-shaped concave part 5 so as to protrude along the central axis of a shaft 2. A conical recess 20 that accommodates the conical supporting protrusion in a manner that allows relative rotation is formed in the center of the tip surface of a truncated cone-shaped convex part 3. A shaft-retaining surface 37, which faces the base end face 13 on the maximum-diameter side of the truncated cone-shaped convex part with a slight gap therebetween, and which restricts the sliding movement of the shaft, is formed in a cover member 10. A dynamic-pressure-generating groove 38 that generates dynamic pressure when the shaft rotates is formed in the shaft-retaining surface. When the shaft is rotating, precession between the shaft and a sleeve 4 is suppressed by dynamic pressure generated in the dynamic-pressure-generating groove and aligning function generated in an engaging part of the conical supporting protrusion and the conical recess. |
