| 摘要 |
<P>PROBLEM TO BE SOLVED: To drive a rotating body at a high speed, and stabilize the friction torque thereof. <P>SOLUTION: A bearing device 8 includes: a sleeve 27 having a protrusion integrally formed at a center of an inside face and protruding toward the center, and two ball bearings 25, 26 each having an axial end of an outer ring in contact with a step section formed at both sides of the protrusion. The material of the sleeve is a heat-treated aluminum silicon alloy including an aluminum of 60 to 90 wt.%, a silicon of 9 to 39 wt.%, and other metallic materials of 1 to 5 wt.%, where they total 100 wt.%. The density thereof is 2.52 to 2.66 g/cm<SP>3</SP>. A shaft 21 having a linear expansion coefficient smaller than that of the sleeve is inserted to the ball bearings. <P>COPYRIGHT: (C)2009,JPO&INPIT |
