Minebea Mitsumi Inc.

Kazuo Ota

Hideaki Showa

Daigo Nakajima

A fluid dynamic bearing device prevents an oleophobic agent from wetting and spreading to a tapered seal portion, including lubricating oil C filled in a condition in which the oil is separated sandwiching a separator portionholding a gas layer arranged between two conical bearing members, and two primary tapered seal portionseach connecting to one of both ends along an axial direction of the separator portion, wherein width in a radial direction of the two primary tapered seal portiondecreases as each approaches toward the two conical bearing members, a gas-liquid interface of the lubricating oil C is located each of the two primary tapered seal portions, an oleophobic agent blocking portionis arranged at each of both ends in an axial direction of the separator portion, a separator central portionis arranged between the oleophobic agent blocking portionsof the separator portions, and an oleophobic coating is formed at least at the separator central portionof the separator portion

Fluid dynamic bearing device, spindle motor, and hard disk drive device

A fluid dynamic pressure bearing includes a conical bearing member having a conical bearing surface forming a first gap between a member constituting the rotor. A second gap connected to one end of the first gap and provided over the entire periphery of the shaft is formed between the conical bearing member and the shaft. A tapered seal portion is formed between the conical bearing member and the rotor. The conical bearing member is provided with a circulation hole that communicates the second gap and the tapered seal portion. The circulation hole communicates to another end of the first gap through a part of the tapered seal portion, so that the circulation hole and the other end of the first gap are spaced apart.

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Komoro, Japan

Kazuo Ota