| 摘要 |
PROBLEM TO BE SOLVED: To level a holding amount of lubricant held at each bearing part for rotating stably when a pair of radial dynamic pressure bearing parts separated by an air intervening part and a pair of thrust dynamic pressure bearing parts next to the radial dynamic pressure bearing parts respectively are constituted. SOLUTION: Each of the pair of radial dynamic pressure bearing parts 28a, 28b is placed next to each of the pair of thrust dynamic pressure bearing parts 32a, 32b respectively. The pair of thrust dynamic pressure bearing parts is functioned such that each of them is pumped to the adjoining radial dynamic pressure bearing part side for the lubricant 24 held in thrust small gaps respectively. An expanding gap part 19a of which a gap size between an outer circumferential face of a thrust plate 4a and a plate facing inner circumferential face 18c changes circumferentially and continuously and an opening is made outward in an axial direction is formed in a part, in a circumferential direction at a gap in a radial direction of an outer circumference of the thrust plate 4a. At least one lubricant communicating passage 34 adapted to communicate between each of outer circumferential end parts of the pair of thrust small gaps is formed on a sleeve body 6a.
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