Patent ID: 6686674
Filing Date: 2004-02-03
Classification: F16C,G11B,H02K

Abstract:
A fluid dynamic bearing motor, comprising:a shaft including a truncated cone shaped side wall diminishing its diameter toward a free end of the shaft; a sleeve having an inner wall forming a conical concavity accommodating the shaft and surrounding the side wall and the free end of the shaft, the inner wall opposing the wall of the shaft with a clearance; electric magnetic means for causing relative movement of the shaft and the sleeve; lubricant filled in the clearance; a single series of herringbone grooves, formed on one of the side wall of the shaft and the inner wall of the sleeve, each of the grooves being composed of a pair of pumping out grooves inclined to pump out the lubricant when the shaft and the sleeve move relative to each other and a pumping in groove inclined to pump in the lubricant when the shaft and the sleeve move relative to each other, the pair of the grooves being inclined to form a substantially V-shape to increase the pressure between the pair of grooves and exert a force perpendicular to the plane of the side wall of the shaft, the perpendicular force causing a moment around the imaginary fulcrum of the cone; and magnetic means for causing an attractive force counter balancing vertical component of the force caused by the groove.