| 摘要 |
A fluid dynamic bearing device (1) including: a bearing sleeve (8) fixed to an inner periphery of a housing (7); a shaft member (2) removably inserted along an inner periphery of the bearing sleeve (8); an annular member (9) having an inner peripheral surface (9a) for defining a radial gap (Ga) together with an outer peripheral surface (2a) of the shaft member (2); and radial bearing portions (R1, R2) and a thrust bearing portion (T) for supporting the shaft member (2). At least the radial bearing gap (Gr) at each of the radial bearing portions (R1, R2), and a bottom gap (Gb) having the thrust bearing portion (T) received therein are filled with lubricating oil (11). A void section is formed in an interior space of the housing (7). Assuming that d 1 represents a gap width of the radial bearing gap (Gr) and d 2 represents a gap width of the radial gap (Ga), a relationship of 30d 1 ‰¤d 2 ‰¤250d 1 is satisfied. |
