Patent ID: 6040648
Filing Date: 2000-03-21
Classification: F16C,H02K

Abstract:
A spindle motor comprising: a housing; a rotating shaft mounted to the housing to undergo rotational movement, the rotating shaft having a rotor supporting portion, a thrust bearing portion, and a radial bearing portion; a rotor fixed to the rotor supporting portion of the rotating shaft to undergo rotational movement therewith; a magnet mounted to the rotor; a stator having a stator coil fixed to the housing to oppose the magnet and to generate a magnetic force in cooperation with the magnet to cause the rotor and the rotating shaft to undergo rotation; a liquid dynamic pressure bearing comprising opposing surfaces of the housing and the rotating shaft; the thrust bearing portion of the rotating shaft comprising a disk-shaped member formed at an intermediate portion of the rotating shaft between the rotor supporting portion and the radial bearing portion, and having a larger diameter than said other portions of the rotating shaft, the radial bearing portion and the rotor supporting portion being formed at opposite axial ends of the rotating shaft; a cylindrical hole formed in the housing in which the thrust bearing portion and the radial bearing portion of the rotating shaft are supported to undergo rotational movement, the cylindrical hole having a first portion with a first diameter in which the radial bearing portion is disposed and a second portion with a second diameter larger than the first diameter in which the thrust bearing portion is disposed; lubricant oil filled in a portion of the cylindrical hole surrounding the thrust bearing portion and the radial bearing portion; and a presser ring fixed to the housing to cover the cylindrical hole around the rotating shaft to seal the lubricant oil in the housing; wherein the rotor has a boss portion formed at a center thereof, the boss portion having an inner peripheral surface which contacts and is fixed to the rotor supporting portion of the rotating shaft, and wherein a magnetic center of the magnet in the axial direction of the rotating shaft and a magnetic center in the same direction of the stator coil are substantially matched.