Fluid dynamic pressure bearing device

Abstract

Desired bearing performance may be maintained stably with a fluid dynamic pressure bearing device supporting relative rotation both in normal and reverse directions. A fluid dynamic pressure bearing device (1) comprises: a first portion (B1) in which a dynamic pressure groove portion (B) where a plurality of axially inclined dynamic pressure grooves (4) are arranged in a circumferential direction is disposed at an outer circumferential surface (2a) of a shaft member (2) or an inner circumferential surface (3a) of a bearing member (3) forming a radial bearing clearance, and the dynamic pressure groove portion (B) generates fluid pressure at the radial bearing clearance when the bearing member (3) and the shaft member (2) rotate relatively in the normal direction; and a second portion (B2) generating fluid pressure at the radial bearing clearance when the bearing member (3) and the shaft member (2) rotate relatively in the reverse direction. An annular convex portion (6), which is closer to the shaft member (2) than to a fillet of the dynamic pressure groove (4), is disposed at a portion forming an edge of a side open to the atmosphere of the radial bearing clearance in the dynamic pressure groove portion (B) disposed in the inner circumferential surface (3a) of the bearing member (3).

Description

technical field [0001] The present invention relates to hydrodynamic bearing devices. Background technique [0002] The fluid dynamic pressure bearing device uses the dynamic pressure of the dynamic pressure groove to generate fluid pressure in the radial bearing gap between the bearing member and the shaft member inserted into the inner circumference of the bearing member, and uses this pressure to make the shaft member and the bearing member move radially. The direction is relatively rotatable and non-contact bearing device. Such a fluid dynamic pressure bearing device can support a shaft member that rotates relatively at high speed with high precision and stably, so it can be well used in spindle motors of disk devices such as HDDs, CD-ROMs, and DVD-ROMs, as well as polygons of laser printers. Bearings for small motors mounted in information equipment such as scanner motors and fan motors for PCs. [0003] In the above-mentioned small motors mounted on information equip...

AI Technical Summary

Problems solved by technology

However, if the bearing device used to support the shaft member for relative rotation in one direction is directly used to support the shaft member for relative rotation in two directions, when the shaft member rotates relative to the opposite direction, the radial bearing may be damaged. Negative pressure is generated in a part of the gap or the oil film formed in the radial bearing gap is broken, so it is difficult to support the shaft member in a non-contact manner in a desired manner.

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