SPINDLE MOTOR FIR STABILIZING A SYSTEM WHEN OIL VISCOSITY IS CHANGED CORRESPONDING TO TEMPERATURE WITH DIFFERENT COEFFICIENTS OF LINEAR EXPANSION OF A ROTATION SHAFT AND A SLEEVE

摘要

PURPOSE: A spindle motor is provided to allow a sleeve to have different coefficients of linear expansion, thereby preventing decrease of rigidity or increase of driving current when oil viscosity is changed corresponding to temperature.;CONSTITUTION: Oil is injected between a rotation shaft and a sleeve. A coefficient of linear expansion of the rotation shaft is larger than a coefficient of linear expansion of the sleeve. Rigidity of a hydrodynamic bearing is not degraded corresponding to reduction of a gap between the rotation shaft and the sleeve. Friction and driving current are not increased corresponding to enlargement of the gap between the rotation shaft and the sleeve.;COPYRIGHT KIPO 2013;[Reference numerals] (AA,DD) Temperature decrease; (BB) Oil viscosity decrease; (CC) Gap between a rotation shaft and a sleeve become narrow; (EE) Oil viscosity increase; (FF) Gap between the rotation shaft and the sleeve become wide