Hydrodynamic pressure bearing, spindle motor in which it is utilized, and disk-drive device furnished with the spindle motor

Abstract

Spindle-motor hydrodynamic bearing configuration having conical taper seals on the thrust-bearing ends. The spindle motor shaft is supported in a bore through the rotor by neighboring radial and thrust hydrodynamic bearings constituted through radial micro-gaps cylindrically between the shaft and rotor, axial micro-gaps between thrust plates on either shaft end and recesses endwise in the rotor bore, dynamic-pressure-generating grooves in the micro-gap forming surfaces, and lubricant retained continuously in the radial and axial micro-gaps. The thrust plates are at least partially conical, tapering axially outward. A ring fitted in each rotor bore recess has a conical inner peripheral surface corresponding to the opposing conical surface of the thrust plate, forming a taper seal sloped with respect to the rotational axial center of the motor. The gap clearance dimension gradually expands heading axially outward, wherein the lubricant forms an axial-end gas-liquid interface to function as a taper seal.