Patent ID: 8876386
Filing Date: 2014-11-04
Classification: F16C,H02K

Abstract:
1. A fluid dynamic bearing device, comprising: a fixed member having a bearing member, a rotational member having a shaft member which is inserted at an inner periphery of the bearing member and comprises a shaft and a flange portion, and a radial bearing gap formed between the bearing member and the shaft member, the rotational member being supported by a film of a fluid formed in the bearing gap, wherein the bearing member is an injection-molded article having an electroformed part as a metal plated portion and a retainer which retains the electroformed part and is formed by the injection-molding integrally with the electroformed part, the electroformed part has a first axial end surface and a second axial end surface orthogonal to a central axis of the electroformed part, the retainer has an adherence face at an inner periphery of the retainer, a first engaging portion, and a second engaging portion, the adherence face adheres to an outer circumferential surface of the electroformed part, the first engaging portion extends inwardly from the adherence face and engages the first axial end surface of the electroformed part, the second engaging portion extends inwardly from the adherence face and engages the second axial end surface of the electroformed part, and the bearing member having a small-diameter inner circumferential surface which forms the radial bearing gap between the small-diameter inner circumferential surface and an outer circumferential surface of the shaft, a large-diameter inner circumferential surface positioned on an outer diameter side of the flange portion, and an attachment surface attachable to a base member, the small-diameter inner circumferential surface is constituted by an inner circumferential surface of the electroformed part, the large-diameter inner circumferential surface is constituted by an inner circumferential surface of the retainer, the inner circumference surface of the retainer is provided on a position different from the adherence face in the axial direction of the retainer, the attachment surface is formed on an outer circumferential surface of the fluid dynamic bearing device, and the outer circumferential surface of the fluid dynamic bearing device is constituted by an outer circumferential surface of the retainer.