JPH04197057A - Bearing structure for motor - Google Patents

Abstract

PURPOSE:To suppress vibration of a high speed motor easily by placing a viscoelastic material between the outer periphery of the outer ring part of a free side bearing having a gap for absorbing differential thermal expansion with respect to a motor housing and the inner periphery of the motor housing. CONSTITUTION:A bearing 14 has inner ring secured to an output shaft 10 and an outer ring fit tightly to the inner surface of a bearing housing 16. Thermal expansion of the output shaft 10 and the bearing section also takes place in the radial direction thereof and thereby each member is dimensioned to provide a gap of about 50nm between the inner peripheral surface 12a and the outer ring part so that the outer ring part of the bearing does not come into press contact with the inner peripheral surface 12a of the housing 12. A viscoelastic member, e.g. a liquid gasket, is then filled in the gap. Essential characteristic of the viscoelastic member are non-drying, oil resistant and heat resistant upto 70-80 deg.C. The viscoelastic material can be filled by simply applying it onto the outer periphery of the bearing housing 16.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a bearing structure for an electric motor for vibration reduction.

[Conventional technology]

Generally, the output shaft bearing of an electric motor is at a higher temperature than the electric motor housing, so it is necessary to absorb elongation due to thermal expansion of the output shaft. For this reason, the output shaft often has a fixed side bearing in which the outer ring of one of the front and rear bearings is fixed to the motor housing in the axial direction, and a free side bearing that is free in the axial direction.

Examples of the structure of the free side bearing portion are shown in Figs. 2 and 3. The outer ring of the bearing 14 on the rear side of the output shaft 10 is integrated with a bearing housing 16.
is set to have, for example, a gap of about 2 nm in the axial direction with respect to the motor housing 12, and a gap of about 5 Qnm in the radial direction.

The gap is elastically filled in the axial direction by the unib washer 22, and the gap is filled in the radial direction by the coil spring 18 and the ball 20. Further, in the case of FIG. 3, in the radial direction, pressure oil is supplied to the gap region surrounded by the pair of O-rings 24, thereby elastically filling it.

[Problems to be Solved by the Invention] However, in any of the above methods, although it is possible to release the thermal expansion of the shaft, it is almost impossible to absorb vibrations during high-speed rotation. Even if it is possible to provide a vibration damping effect by controlling the strength of the coil spring and the hydraulic pressure, the structure and device become complicated. Furthermore, if the spring pressure or oil pressure is made too strong, the life of the bearing during high-speed rotation will be shortened.

Therefore, an object of the present invention is to reduce the vibration of a high-speed rotating electric motor using a simple letter.

[Means for Solving 5 Problems] In view of the above object, the present invention provides a bearing for an output shaft of an electric motor, and provides an outer ring portion of a free side bearing having a gap between it and the electric motor housing to accommodate a difference in thermal expansion. Provided is a bearing structure for an electric motor, characterized in that a viscoelastic body is interposed between the outer periphery of the motor housing and the inner periphery of the electric motor housing.

[For production]

The viscous action of the viscoelastic body reduces the vibration of the free side bearing, and it is easy to intervene because it can be interposed simply by applying it.

〔Example〕

The present invention will be described in more detail below based on embodiments shown in the accompanying drawings. FIG. 1 is a sectional view of the rear end of the electric motor, showing the free side bearing. Therefore, the stationary side bearing is provided at the front of the electric motor. The inner ring of the bearing 14 is fixed to the output shaft 10, and the outer ring is tightly fitted to the inner surface of the bearing housing 16.

A ring member 28 covers the inside in the axial direction. The bearing housing 16 constitutes the outer ring portion of the bearing 14, and an axial clearance 32 is provided between the bearing housing 16 and the electric motor housing 12 in order to release the axial extension due to thermal expansion of the output shaft 10. It is held elastically with a washer 22 interposed therebetween.

Furthermore, the thermal expansion of the output shaft 10 and the bearing portion also extends in the radial direction, and the outer ring portion of the bearing comes into pressure contact with the inner circumferential surface 12a of the motor housing 12, impeding the aforementioned axial extension of the output shaft 10. To prevent this, the dimensions of each member are designed to provide a gap of approximately 5Q nm between the inner circumferential surface 12a and the outer ring portion. In the present invention, for example, a liquid manufactured by Three Pond Company is used in the above-mentioned gap.
Fill with a viscoelastic material such as (trade name). The required properties of this viscoelastic body include non-drying, oil resistance, and 70 to 80%
It has heat resistance up to ℃. The filling method is
It is easy to simply apply it to the outer periphery of the bearing housing 16 during assembly. In this way, since a viscoelastic body having an appropriate viscosity exists between the bearing outer ring portion and the motor housing, vibration of the output shaft 10 can be reduced.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, vibrations of the electric motor can be easily reduced.

[Brief explanation of the drawing]

FIG. 1 is a rear sectional view of an electric motor having a bearing structure according to the present invention, FIG. 2 is a sectional view showing one example of a conventional structure, and FIG. 3 is a sectional view showing another example of the conventional structure. 10... Output shaft, 12... Electric motor housing,
14...Bearing, 16...Bearing housing, 2
2... Unibu washer, 30... Viscoelastic body.

Claims (1)

[Claims] 1. A bearing for the output shaft of an electric motor, in which a viscoelastic body is provided between the outer circumference of the outer ring portion of the free side bearing, which has a gap between it and the electric motor housing to absorb the difference in thermal expansion, and the inner circumference of the electric motor housing. A bearing structure for an electric motor characterized by interposing.