| 摘要 |
It is an object of the invention to provide a thrust dynamic pressure bearing in which complex small holes or the like are not disposed so that the production cost is not increased, and negative-pressure suction which may be caused at start of rotation is prevented from occurring, thereby enabling the bearing to correctly function as a thrust dynamic pressure bearing.In solving means for the above, a rotor 1 in which thrust dynamic pressure generating grooves are formed in an end face, and a housing 2 which accommodates the rotor 1 in a hermetically sealed state with forming small gaps 3 and 4 therebetween are disposed. The gaps are filled with a working fluid L for generating a dynamic pressure. Pockets (1p, 2P) which serve as spaces for accumulating the working fluid are formed in the end face 1a of the rotor 1 and an end face 2a of the housing 2 that is opposed to the end face 1a, respectively. A total of capacities of the pockets is 50 times or more the capacity of the bearing gap 3 between the end face of the rotor 1 and the end face of the housing 2. Furthermore, the bearing gap 3 is inclinedly reduced as moving toward a radially outer side.
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