Nidec Corporation

Shinya Tokunaga

Kaoru Uenosono

Hideki Nishimura

Yoshito Oku

Harushige Osawa

Ming Feng

Mitsuhiro Kurino

Itsuo Murata

In a radial minute gap between a substantially columnar shaft and an inner peripheral face of a substantially cylindrical sleeve, oil is retained and a radial dynamic pressure bearing is formed. A plurality of recessed portions are arranged in a circumferential direction on at least one of an outer peripheral face of the shaft and the inner peripheral face of the sleeve and a first hill portion is provided to an axial end portion of each the recessed portion. Thus, it is possible to achieve a dynamic pressure bearing with which sufficient radial shaft support can be obtained in spite of a short axial length.

Fluid dynamic pressure bearing and recording disk drive device comprising the same

In a spindle motor, in an upper portion of a stator bearing surrounding wallof a bearing housing, a flangeprojecting outward in the radial direction from the stator bearing surrounding wallis provided, and a tapered faceobtained in such a manner that the outer diameter of the bearing housinggradually decreases downward from the flangeis formed in the outer face of the stator bearing surrounding wall. A rotorhas a yokefacing the bearing housingin the radial direction and the air-fluid boundary is formed in a fifth clearancebetween the tapered faceand the inner face of the yoke. By the yokeand the flangewhich are fit to each other in a non-contact state, a detachment preventing structure is constructed.

Spindle motor and recording disk driving apparatus having the spindle motor

In a spindle motor utilizing dynamic-pressure bearings having a full-fill structure, a bearing configuration that balances and sustains at or above atmospheric pressure the internal pressure of the bearing oil. Thrust and radial bearing sections are configured within oil-filled bearing clearances in between the rotor, the shaft, and a shaft-encompassing hollow bearing member. A communicating passage one end of which opens on, radially inwardly along, the thrust bearing section is formed in the bearing member. Either axial ends of the bearing clearance in between the bearing member and shaft communicate through the passage. The communicating passage enables the oil to redistribute itself within the bearing clearances. Pressure difference between the axial upper and lower ends of the oil retained in between the bearing member and the shaft is compensated through the communicating passage, preventing incidents of negative pressure within the oil and of over-lift on the rotor.

Spindle motor and disk drive furnished therewith

Spindle motor utilizing a dynamic-pressure bearing device having a full-fill structure and capable of discharging air bubbles from the lubricating oil after it is charged into the bearing device, as well as air bubbles appearing in the oil due to cavitation in handling. Thrust and radial bearing sections are configured within bearing clearances in between the rotor, the shaft, and a shaft-encompassing hollow bearing member. A communicating passage enabling the oil to redistribute itself within the bearing clearances is formed in the bearing member. At least one ray-like groove that reaches from the radially inward edge of dynamic-pressure-generating grooves in the thrust bearing section to the rim of the shaft-encompassing hollow is furnished in the bearing member. When the motor rotates the air bubbles are stirred and minced by the ray-like groove, and migrate toward release at the single oil-air interface.

Spindle motor that has high rotational precision and is manufacturable at low cost, and that can be applied even in miniature, low-profile recording-disk drives. The spindle motor includes a shaft having a cone portion, a conic-shaped cavity into which the cone portion is inserted, and only a single dynamic-pressure bearing, formed on the lateral face of the cone portion. The working fluid is oil, and the oil fills without interruption a clearance between the shaft's cone portion and the conical cavity.

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Koga-gun, Japan

Shinya Tokunaga