Abstract: A fluid dynamic pressure bearing has an annular dynamic pressure generating face having a dynamic pressure generating groove, which draws a working fluid toward a midway position in the radial direction from the inside and outside of a thrust bearing plate in the radial direction when a shaft and a housing are rotated relative to each other. The dynamic pressure generating groove is provided on thickness direction end faces of the thrust bearing plate or on an inner surface of the housing, and an inner groove section is located on an inner peripheral side of the dynamic pressure generating face on the end faces and is recessed more than the dynamic pressure generating face in the thickness direction. A through-hole extends through the thrust bearing plate in the thickness direction so as to open to the dynamic pressure generating face, and a communicating cavity connects the opening portion of the through-hole and the inner groove section.

Abstract: The generation of bubbles can be suppressed by enabling a stable supply of working fluid to a dynamic pressure generating groove, and oscillation at the time of rotation and leakage of working fluid can be prevented effectively by efficiently releasing any bubbles generated. There is provided a fluid dynamic pressure bearing 1 provided with an annular dynamic pressure generating face 17 made by forming a dynamic pressure generating groove, which draws a working fluid 14 toward a midway position in the radial direction from the inside and outside of a thrust bearing plate 13 in the radial direction, when a shaft 10 and a housing 11 are rotated relative to each other about the axis, on thickness direction end faces 13a, 13b of the thrust bearing plate 13, or on an inner surface of the housing 11, and an inner groove section 16, which is located on an inner peripheral side thereof and that is depressed more than the dynamic pressure generating face 17 in the thickness direction, on the end faces 13a, 13b.

Abstract: In a hydraulic bearing motor, by means of dynamic pressure generating grooves provided on a thrust shaft with a larger diameter not only on the end face thereof but also on the shaft surface thereof, pressures generated in oil when rotating a shaft body are made to be applied not only in the axial direction but also in the radial direction with high magnitude. This can provide the hydraulic bearing motor as being capable of satisfying features of exhibiting small NRRO, and vibration and shock resistance even with a thinned hydraulic bearing motor.

Abstract: A hydraulic dynamic pressure bearing motor has a rotational shaft mounted to undergo rotation about a rotational axis and having a shaft section and a flange section. A sleeve has a cavity for receiving the rotational shaft. A cover member is disposed over an open end of the sleeve cavity. A hydraulic dynamic pressure bearing includes minute radial and thrust clearances disposed between outer surface portions of the shaft and flange sections of the rotational shaft and inner surface portions of the sleeve and the cover member. A lubricating fluid is disposed in the minute radial and thrust clearances. The minute radial and thrust clearances are 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 an inner peripheral surface of the cover member.

Abstract: In a spindle motor, a core with a specified thickness is formed by laminating thinnest possible magnetic steel sheets to allow consumed current to be reduced. For example, by providing a structure of a core of a spindle motor with seven 0.2 mm thick steel sheets being laminated, it becomes possible to make consumed current smaller than that for a core laminated with four 0.35 mm thick steel sheets. Thus, a spindle motor is provided as being suited for downsizing an HDD and possible to reduce consumed power.

Abstract: In a thin dynamic pressure hydraulic bearing motor used for a compact HDD device which motor is provided with a thin hydraulic dynamic pressure bearing comprising a flanged rotary shaft comprising a shaft and a flange, a sleeve into which the flanged rotary shaft is rotatably inserted, a ring-like lid 35, and lubricating oil filling minute clearances formed by those bearing components, the thrust clearance c is determined as being equal to or less than a value for which a product md of the maximum vertical shift m at a rim of a magnetic disk and a diameter d of the flange of the flanged rotary shaft is divided by 4r, four times a radius r of the magnetic disk. Thus, even when no bearing stiffness is provided for the hydraulic dynamic pressure bearing motor at rest, the magnetic disk is made so as not to contact with a head supporting system such as a head loading arm.

Abstract: In a hydraulic bearing motor, by means of dynamic pressure generating grooves provided on a thrust shaft with a larger diameter not only on the end face thereof but also on the shaft surface thereof, pressures generated in oil when rotating a shaft body are made to be applied not only in the axial direction but also in the radial direction with high magnitude. This can provide the hydraulic bearing motor as being capable of satisfying features of exhibiting small NRRO, and vibration and shock resistance even with a thinned hydraulic bearing motor.