| 摘要 |
PROBLEM TO BE SOLVED: To prevent fluid from leaking out to the outside during high speed rotation, in a motor having a thrust bearing formed out of a pair of thrust plates. SOLUTION: A ring-shaped gas-filled part is formed around a part, where a communicating hole is open in a shaft 4. With a fluid retained at the axially- upper and lower parts of an air-interposed part of a minute gap which is formed by the shaft 4 and a rotor 6 facing in the radial direction, a herringbone-shaped groove 24 having an axially unbalanced shape is formed on at least one of the shaft or the rotor, so that the fluid can be press-fed in the direction counterpoising the gas-filled part, thereby forming a pair of radial bearing parts 26, 28. With the fluid retained continuously from the fluid held in the radial bearing parts in a minute gap formed by a pair of thrust plates 4a, 4b and the rotor 6 facing in an axial direction, a spiral-shaped groove 14 having a shape with the fluid capable of being press-fed in the radially inward direction is formed on at least one of a pair of thrust plates and the rotor.
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