Patent ID: 6307291
Filing Date: 2001-10-23
Classification: F16C,G11B,H02K

Abstract:
A fluid dynamic pressure bearing, comprising:a fixed shaft having at least one of a pair of ends fixedly mountable to an apparatus;a rotary sleeve having an inner peripheral surface arranged adjacent to an outer peripheral surface of the fixed shaft to provide a first fine gap between the inner peripheral surface of the rotary sleeve and the outer peripheral surface of the fixed shaft;a fixed sleeve having an inner peripheral surface arranged adjacent to an outer peripheral surface of the rotary sleeve to provide a second fine gap between the inner peripheral surface of the fixed sleeve and the outer peripheral surface of the rotary sleeve; anda holding member for holding the fixed shaft and the fixed sleeve arranged adjacent to a lower end surface of the rotary sleeve to provide a third fine gap between the holding member and the lower end surface of the rotary sleeve;wherein at least one of the first fine gap and the second fine gap is formed with radial dynamic pressure producing grooves and the third fine gap is formed with a thrust dynamic pressure producing groove, and the first, second and third fine gaps are filled with a lubrication oil so that the rotary sleeve is supported to undergo rotational movement with respect to the fixed shaft and the fixed sleeve; andwherein the first fine gap and the second fine gap each have one open end which is in contact with air outside the bearing and one closed end which is not in contact with the air, and the closed ends of the first and second fine gaps are in communication with each other through the third fine gap.