Patent ID: 6951025

Claim:
A gas dynamic pressure bearing, comprising: a shaft; a hollow cylindrical sleeve in which the shaft is disposed such that it can freely rotate relative thereto; a first thrust dynamic pressure bearing, the thrust dynamic pressure bearing comprising a first thrust bearing surface on the shaft, a first thrust bearing surface on the sleeve which faces the first thrust bearing surface on the shaft across a gap in an axial direction, and dynamic pressure generating grooves formed in at least the first thrust bearing surface on the shaft or the first thrust bearing surface on the sleeve; and a radial dynamic pressure bearing comprising an inner circumferential surface of the sleeve, an outer circumferential surface of the shaft which faces the inner circumferential surface of the sleeve across a gap in a radial direction, dynamic pressure generating grooves formed in at least the inner circumferential surface of the sleeve or the outer circumferential surface of the shaft, and a flat region having no dynamic pressure generating grooves formed on an end portion of the radial dynamic pressure bearing near the thrust dynamic pressure bearing; wherein: when the shaft rotates relative to the sleeve, the dynamic pressure generating grooves of the thrust dynamic pressure bearing produce a pressure differential in gas disposed in the gap of the thrust dynamic pressure bearing so that the pressure of the gas increases in the radial direction, and the dynamic pressure generating grooves of the radial dynamic measure bearing produce a pressure differential in gas disposed in the gap of the radial dynamic pressure bearing so that the pressure of the gas increases in the axial direction; an end portion of the gap of the thrust dynamic measure bearing where the pressure of the gas therein is increased is connected to an end portion of the gap of the radial dynamic pressure bearing where the pressure of the gas therein is increased; and a portion of the gap of the thrust dynamic measure bearing where the pressure of the gas therein is reduced is in gaseous communication with a portion of the gap of the radial dynamic measure bearing where the pressure of the gas therein is reduced via a gaseous communication means.