| 摘要 |
PROBLEM TO BE SOLVED: To provide a fluid dynamic pressure bearing that can exhibit desired bearing performance while being capable of being manufactured at low cost.SOLUTION: A fluid dynamic pressure bearing device 1 comprises: a bearing sleeve 8 fixed to an inner periphery of a cylindrical housing 7 with a closed bottom; a shaft member 2 detachably inserted into an internal periphery of the bearing sleeve 8; an annular member 9 having an inner peripheral surface 9a that provides a radial gap Ga between the inner peripheral surface 9a and an outer peripheral surface 2a of the shaft member 2; radial bearing portions R1, R2 supporting the shaft member 2 in a radial direction; and a thrust bearing portion T supporting one end of the shaft member 2. A bottom gap Gb housing at least a radial bearing gap Gr of the radial bearing portions R1, R2 and the thrust bearing portion T is filled with a lubricating oil 11. An air gap is provided in an interior space of the housing 7, and the relational expression: 30d≤d≤250dis satisfied, provided that a gap width of the radial bearing gap Gr is represented as d, and a gap width of the radial gap Ga is represented as d. The air gap is constituted of at least a part of a communication path 12 that allows communication between the radial gap Ga and the bottom gap Gb. |
