Patent ID: 6870289

Claim:
A hydrodynamic bearing, comprising: a column-like shaft; a hollow cylindrical sleeve being fitted on an outer circumferential surface of said shaft so as to achieve relative rotation among the two; and a thrust plate being directly or indirectly attached to or integrated with either one of said shaft and said sleeve, which thrust plate being faced with a plane formed at one end of the other one of said shaft and said sleeve perpendicular to an axis of said bearing, wherein hydrodynamic pressure in a radial direction being generated at a radial bearing portion formed by an outer circumferential surface of said shaft and an inner circumferential surface of said sleeve, and hydrodynamic pressure in a thrust direction being generated at a thrust bearing portion formed by said thrust plate and said plane which is faced with said thrust plate and formed at said one end of said other member perpendicular to said axis, the hydrodynamic bearing is characterized in that either one of the surfaces forming said radial bearing portion is provided with a groove or grooves configured to generate a force in a thrust direction via a fluid located in the radial bearing portion so as to cause an axial movement of either one of the shaft and the sleeve through relative rotation therebetween, said relative rotation being in a direction that causes axial movement of the sleeve or the shaft in a direction that reduces a gap between the two facing members at said thrust bearing portion, and either one of the surfaces of said two facing members at said thrust bearing portion is provided with a groove or grooves which generate hydrodynamic pressure in said thrust direction.