Patent ID: 7134791
Filing Date: 2006-11-14
Classification: F16C,G11B,H02K

Abstract:
1. A dynamic pressure bearing device comprising a base, a shaft fixed to the base, and a sleeve rotatably arranged around the shaft, characterized in that: a circular thrust plate, which is provided on the shaft and has a diameter larger than that of the shaft portion, and the shaft are formed integrally of a stainless steel into a shaft member; the sleeve is formed of an aluminum silicon alloy containing aluminum and silicon as components, the sleeve having an inner diameter ranging from 0.6 to 3 mm; the shaft member has a coefficient of linear expansion of 17×10 the sleeve has a coefficient of linear expansion of 14×10 a thrust plate portion has an axial thickness of 0.15 to 0.35 mm; a hardness of the sleeve is lower than that of the shaft, with a radial bearing dynamic pressure groove being provided in a portion of the sleeve, which is a softer member, opposed to the shaft; and a counter plate is provided at a position opposed to the thrust plate so as to cover the thrust plate and to close a central hole of the sleeve, a first thrust dynamic pressure groove for a thrust bearing is provided at a position of the counter plate opposed to the thrust plate, and a second thrust dynamic pressure groove is provided in a portion of the sleeve opposed to a surface opposite to the surface of the thrust plate opposed to the first thrust dynamic pressure groove.