Hydraulic dynamic pressure bearing motor

A hydraulic dynamic pressure bearing motor comprising:

• a rotational shaft mounted to undergo rotation about a rotational axis, the rotational shaft having a shaft section and a flange section;
• a rotor having a hub for supporting a rotational member thereon and connected to the rotational shaft for rotation therewith about the rotational axis;
• a stator for generating a force to rotate the rotor by an interactive electromagnetic action between the rotor and the stator;
• a sleeve having a cavity for receiving the rotational shaft so that a preselected portion of the shaft section extends out of the cavity through an open end thereof;
• a cover member disposed over the open end of the sleeve cavity and having a through-hole through which the preselected portion of the shaft section of the rotational shaft extends when the rotational shaft is disposed in the cavity of the sleeve, the through-hole having an inner peripheral surface and a diameter greater than a diameter of the preselected portion of the shaft section;
• and
• a hydraulic dynamic pressure bearing disposed between the rotor and the stator and comprised of outer surface portions of the shaft section and the flange section of the rotational shaft, inner surface portions of the sleeve and the cover member, a plurality of minute radial and thrust clearances disposed between the outer surface portions of the shaft and flange sections of the rotational shaft and the inner surface portions of the sleeve and the cover member, and a lubricating fluid disposed in the minute radial and thrust clearances, the minute radial and thrust clearances being dimensioned so that during a non-rotational state of the rotational shaft, the flange section of the rotational shaft contacts preselected inner surface portions of the sleeve and the cover member while the shaft section of the rotational shaft does not contact any portion of the sleeve and the inner peripheral surface of the cover member.