| 摘要 |
PROBLEM TO BE SOLVED: To prevent the pre-load given to a ball bearing from being ineffective even in case that thermal expansion occurs in each member constituting a motor at high temperature of the motor, by making the ball used for the ball bearing out of ceramic. SOLUTION: In a spindle motor for driving a recording disk, where a rotor hub 4 to mount a recording disk is supported rotatably through a pair of ball bearings 6a and 6b equipped with ceramic balls and the material of the outer rings of the pair of the ball bearings 6a and 6b is smaller in thermal expansion coefficient than the material of the rotor hub 4, a cylinder 4a to engage and fix the pair of the ball bearings 6a and 6b, a boss part 4c to abut on the inner end faces of the several facing outer rings of the pair of ball bearings 6a and 6b, and vacant space parts 4d1 and 4d2 provided outward in diametrical direction of the fixing part 4e1 and 4e2 of the cylinder 4a to the pair of ball bearings 6a and 6b are made at the rotor hub 4. |
