Bearing unit and rotation and drive device

Abstract

The present invention provides a bearing unit. A bearing unit rotatably supporting a shaft (2), comprising a radial bearing (4) rotatably supporting the shaft (2) and a resin housing member (6) holding the radial bearing (4), wherein the housing member (6) is formed of a material having a coefficient of heat contraction larger than that of a material used for the radial bearing (4). Where the radial thickness of the radial bearing (4) is m and the radial thickness of the housing body part of the housing member (6) covering the outer periphery of the radial bearing is n, the requirement of m > n is satisfied. Thus, effect by heat contraction in molding can be prevented from being applied to the radial bearing.

Description

technical field [0001] The present invention relates to a bearing assembly and a rotary driving device using the bearing assembly, in particular to a bearing assembly with maintained mechanical precision and improved reliability and a rotary driving device using the bearing assembly. [0002] This application claims priority based on Japanese Patent Application No. 2003-056696 filed in Japan on March 4, 2003, which is incorporated herein by reference. Background technique [0003] Conventionally, as a bearing unit that supports a rotating shaft with high precision and has excellent durability, there are, for example, bearing units for cooling fans used to cool heat-generating devices such as CPUs (Central Processing Units), recording and reproducing devices using tape-shaped recording media, etc. The bearing assembly of the motor used in the drive of the rotating drum. As such a bearing assembly, a bearing assembly using a fluid dynamic pressure bearing as described in JP-A...

AI Technical Summary

Problems solved by technology

[0005] For example, in a bearing assembly using metal housing members, it is difficult to completely bond or connect the constituent parts, and it is difficult to reliably prevent the leakage of lubricating oil.

Moreover, the work of uniformly applying a polymer packing material such as an adhesive to the entire peripheral surface of the connecting part is complicated and expensive, and it is difficult to obtain an inspection method for confirming whether there is no gap and is completely sealed. As a result, , or cannot obtain sufficient reliability, or require expensive equipment

[0006] Furthermore, in a bearing assembly using a resin housing member, for example, when the housing member is formed of a material with a higher heat shrinkage rate than that used for radial bearings, the thermal shrinkage of the housing member may cause Stress toward the inner diameter affects radial bearings

That is, the required distance between the shaft and the radial bearing cannot be secured sufficiently, which may make it difficult to maintain mechanical accuracy

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