JPH0882362A - Idler pulley - Google Patents

Abstract

PURPOSE: To suppress the sound of an idler pulley, especially noise during cold time. CONSTITUTION: Two annular grooves 2b2 and 2b2 are formed in the outside diameter surface 2b1 of an outer wheel 2b and a damping material 3 having resiliency is arranged. The damping material 3 is formed of synthetic resin and molded integrally with the annular groove 2b2. The outside diameter surface 2b1 of the outer wheel 2b is pressed in the inside diameter of the inside diameter cylinder part 1b of a pulley body 1 with a given interference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an idler pulley,
In particular, the present invention relates to an idler pulley that is locked to a timing belt of an automobile engine and a belt for driving auxiliary equipment.

[0002]

2. Description of the Related Art For example, in order to reduce the weight of an idler pulley for an automobile, a pulley main body 11 and a ball bearing 12 as shown in FIG. The pulley body 11 is made of a press-formed steel plate, and has an outer diameter cylindrical portion 11a for hanging a belt (not shown) and an inner diameter cylindrical portion 11 for fitting the outer ring 12b of the ball bearing 12.
b and. The ball bearing 12 is of a deep groove type and has an inner ring 12a fitted to a shaft (not shown), an outer ring 12b fitted to the inner diameter cylindrical portion 11b of the pulley body 11, and raceway surfaces of the inner and outer rings 12a, 12b. A plurality of balls 12 interposed between
c, a cage 12d made of synthetic resin for holding the balls 12c at equal intervals around the circumference, and a seal 12e for sealing grease. In this idler pulley, when the pulley body 11 is rotated by receiving a rotational driving force from the belt, the outer ring 12b of the ball bearing 12 fitted therein rotates together with the pulley body 11.

[0003]

By the way, when the above idler pulley is operated in cold weather, an abnormal sound may be generated. The cause of this abnormal noise during cold weather, so-called abnormal noise during cold weather, has not been clarified yet.
Moreover, idler pulleys used in automobiles etc.
Since it is operated at high speed and under high load, and its durability is also an important characteristic, it is not possible to take measures to reduce durability. For this reason,
The actual situation is that no effective means to determine the noise of the idler pulley when it is cold is provided.

Conventionally, as a measure against abnormal noise during cold, a grease having excellent low temperature characteristics (an oil film is formed evenly in the contact portion between the rolling elements and the raceways of the inner and outer rings even in cold weather) Is being considered for use. This countermeasure is intended to suppress the generation of abnormal noise during cold by improving the lubrication performance of grease during cold weather, and can be expected to have a considerable effect. However, since the viscosity of grease becomes low, there is concern about lubrication performance at high temperatures,
It may lead to a decrease in durability.

It has also been reported that the generation of abnormal noise during cold is suppressed by increasing the radius of curvature of the raceway surfaces of the inner and outer rings and increasing the bearing clearance. The increase in clearance results in amplification of angular runout of the pulley body, which may impair the function of the idler pulley.

Furthermore, a case (a rubber-like elastic body) having a sound absorbing effect is attached to the outer diameter surface of the boss portion (the portion corresponding to the inner diameter cylindrical portion 11b in FIG. 3) of the pulley body (actual flat blade 3-).
No. 41247), or an example in which an elastic body is interposed between the inner diameter of the pulley body and the outer diameter surface of the bearing case into which the rolling bearing is fitted (Actual No. Sho 62-91056).
issue). However, in the former configuration, since the member having the sound absorbing effect is exposed in the atmosphere, it is necessary to use an expensive material in consideration of rust resistance, high temperature resistance, and chemical resistance in some cases, and the cost is a problem. Becomes In the latter configuration, the angular runout of the pulley body may be amplified by the elastic deformability of the elastic body interposed between the inner diameter of the pulley body and the outer diameter surface of the bearing case.

Therefore, the present invention intends to provide means for effectively suppressing the abnormal noise at the time of cold, while ensuring the durability of the idler pulley and the function as the pulley, while also considering the cost. Is.

[0008]

In the present invention, an annular groove is provided on the outer diameter surface of the outer ring of the rolling bearing, and an elastic vibration absorbing material is arranged in this annular groove. Pressed into the inner diameter.

[0009]

[Function] At the time of cooling, unevenness of the oil film due to increase in viscosity of the grease is likely to occur. If there is unevenness or unevenness of the oil film, the friction coefficient between the rolling elements and the raceways of the inner and outer rings causes a minute periodic change, which causes self-excited vibration of the rolling elements. In particular, when there is an oil film cut portion, the rolling element causes a stick slip at that portion, and the state change of rolling / sliding is periodically repeated, so that the amplitude / frequency of the self-excited vibration of the rolling element becomes larger. Then, such self-excited vibration of the rolling element is transmitted to the pulley main body through the outer ring, resonates with the natural vibration of the pulley main body, is amplified, and appears as a resonance sound (cold noise).

According to the present invention, a vibration absorbing material having elasticity is arranged in the annular groove provided on the outer diameter surface of the outer ring, and the self-excited vibration of the rolling element is absorbed by the elasticity of the vibration absorbing material. It tries to prevent it from being transmitted to.

Since the outer diameter surface of the outer ring is press-fitted into the inner diameter portion of the pulley body, the elasticity of the vibration absorbing material is constantly applied to the outer ring and the pulley body (when the self-excited vibration of the rolling element does not reach the resonance region). It does nothing at all. However, when the self-excited vibration of the rolling element approaches the resonance region and the vibrations of the outer ring and the inner diameter portion are amplified, the relative displacement between the two causes a slight elastic deformation of the inner diameter portion, etc. Partial reduction occurs in the interference (press-fit interference). Then, from the time when this interference is partially changed from zero to minus (there is a state with a gap), the elasticity of the vibration absorbing material acts on the outer ring and the pulley body, and the rolling element that tries to be transmitted to the pulley body via the outer ring. It absorbs self-excited vibration.

As described above, the vibration-absorbing material is always a non-existent structure, and when the self-excited vibration of the rolling element approaches or reaches the resonance region that causes the abnormal noise at cold, Only that is what it does. Therefore, amplification of angular runout of the pulley body due to mounting of the vibration absorbing material is avoided, and the function as a pulley is ensured. Further, since the vibration absorbing material is not exposed to the atmosphere, the durability can be secured without using an expensive material in consideration of rust resistance, high temperature resistance, chemical resistance and the like.

[0013]

Embodiments of the present invention will be described below.

The idler pulley shown in FIG. 1 is used for an accessory drive belt of an automobile or the like. The idler pulley includes a pulley body 1 made of a steel plate press and a ball bearing 2 fitted in the inner diameter of the pulley body 1.

The pulley body 1 includes an outer diameter cylindrical portion 1a for hanging a belt (not shown), an inner diameter cylindrical portion 1b located on the inner diameter side of the outer diameter cylindrical portion 1a, an outer diameter cylindrical portion 1a and an inner diameter cylindrical portion. It is a ring body having a substantially U-shaped cross section, which has a connecting portion 1c for connecting 1b and one end surface side. The belt comes into contact with the outer diameter surface of the outer diameter cylindrical portion 1a to serve as an idler.

The ball bearing 2 includes an inner ring 2a fitted to a shaft (not shown), an outer ring 2b press-fitted into an inner diameter cylindrical portion 1b of the pulley body 1, and raceway surfaces of the inner and outer rings 2a, 2b. It is composed of a plurality of balls 2c incorporated, a cage 2d that holds the balls 2c at equal intervals around the circumference, and a pair of seals 2e that seals grease.

As shown in the enlarged view of FIG. 2, two annular grooves 2b2, 2b2 are formed on the outer diameter surface 2b1 of the outer ring 2b, and the elastic vibration absorbing material 3 is arranged in each of these annular grooves 2b2. Has been done. In this embodiment, the vibration absorbing material 3 is made of synthetic resin and is integrally formed with the annular groove 2b2.
A protrusion P is provided on one of the groove shoulders of the annular groove 2b2 to prevent the vibration absorbing material 3 from falling out of the annular groove 2b2 when the outer ring 2b is press-fitted. The inclination angle θ of the projection P is about 30 degrees, and the corners of the groove bottom are rounded surfaces with radii of curvature R1 and R2, respectively. The outer diameter surface 2b1 of the outer ring 2b is press-fitted into the inner diameter of the inner diameter cylindrical portion 1b of the pulley body 1 with a predetermined tightening margin.

The vibration absorbing material 3 may be formed of synthetic resin in an annular shape and fitted in the annular groove 2a1. Further, the vibration absorbing material 3 is not limited to the synthetic resin, and for example, a rubber material integrally molded in an annular groove, a rubber ring such as an O ring fitted in the annular groove, a semi-solid material such as grease, or the like. It may be something like plastic grease.

[0019]

According to the present invention, an annular groove is provided on the outer surface of the outer ring of the rolling bearing, and an elastic vibration absorbing material is arranged in the outer groove, and the outer surface of the outer ring is press-fitted into the inner diameter of the pulley body. Since it has the above-mentioned configuration, it has the following unique effects as the idler pulley.

(1) Since the self-excited vibration of the rolling element caused by the stick slip of the ball or the like at the time of cold is absorbed by the vibration absorbing material and is prevented from being transmitted to the pulley body, the abnormal noise at the time of cold is effectively generated. Can be prevented.

(2) Since the vibration absorbing material is arranged in the annular groove provided on the outer diameter surface of the outer ring, it is not exposed to the outside, and especially considering rust resistance, high temperature resistance, chemical resistance and the like. The durability can be secured without using the expensive material. Therefore, an inexpensive material can be selected as the vibration absorbing material, which is advantageous in terms of cost.

(3) Since the outer diameter surface of the outer ring is press-fitted into the inner diameter of the inner diameter cylindrical portion, the function as a pulley can be ensured by arranging a vibration absorbing material without inconvenience of amplifying angular runout of the pulley body. .

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view (FIG. A) showing the outer ring in FIG.
It is an expanded sectional view (figure b) which shows the annular groove of an outer ring.

FIG. 3 is an enlarged sectional view showing a conventional idler pulley.

[Explanation of symbols]

 1 pulley body 2 ball bearing 2b1 outer diameter surface 2b2 annular groove 3 vibration absorber

Claims (1)

[Claims] 1. An idler pulley comprising a pulley main body and a rolling bearing fitted to the inner diameter of the pulley main body, wherein an outer groove of the outer ring of the rolling bearing is provided with an annular groove, and the annular groove is elastic. With the vibration absorbing material having
An idler pulley in which the outer diameter surface of the outer ring is press-fitted into the inner diameter of the pulley body.