Patent ID: 6971798
Filing Date: 2005-12-06
Classification: F16C,G11B

Abstract:
1. A gas dynamic pressure bearing unit comprising: a stationary part having a cylindrical outer peripheral surface, and a flat surface extending in a radial direction of the cylindrical outer peripheral surface; a rotary part having a hole with a cylindrical inner peripheral surface, and a flat surface extending in a radial direction of the cylindrical inner peripheral surface, said bearing hole into which said stationary part is inserted such that the stationary part and the rotary part can rotate relatively each other; a radial bearing including radial bearing surfaces formed on said outer peripheral surface and said inner peripheral surface, a radial dynamic-pressure-generating groove row formed on one or both of the bearing surfaces, a radial micro-gap formed in between these bearing surfaces, and gas filling said micro-gap; and a thrust bearing including thrust bearing surfaces respectively formed on said flat surface of said stationary part and said flat surface of said rotary part, a thrust dynamic-pressure-generating groove row formed on one or both of the thrust bearing surfaces, an axial micro-gap formed in between these thrust bearing surfaces, and gas filling said micro-gap, wherein: said radial micro-gap is connected to said axial micro-gap through an annular micro-gap portion; said thrust bearing increases a pressure of said gas toward said annular micro-gap portion during relative rotation of said stationary part and said rotary part; said radial bearing increases a pressure of said gas toward said annular micro-gap portion during relative rotation of said stationary part and said rotary part; a portion of said radial micro-gap where the pressure of said gas is lowered comparing to the pressure of the gas at said annular micro-gap portion is in communication with a portion of said axial micro-gap where the pressure of said gas is lowered comparing to the pressure of the gas at said annular micro-gap portion; and at least one particle catching hole is formed in said stationary part, which extends in radial direction of said cylindrical outer peripheral surface, opens to said annular micro-gap portion, the opening being adjacent to an end of one of grooves which constitute said dynamic-pressure-generating groove row.