JP2000337365A - Thrust ball bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of the service life of a thrust ball bearing by eliminating inconvenience such as increase of bearing when a ball contacts with the central projecting part side of a groove recessed part in setting a diameter of a groove bottom pitch circle of orbit grooves smaller than eccentric quantity of turning motion in the thrust ball bearing formed by interposing the ball between the opposed orbit grooves and forming the annular orbit grooves at a constant pitch in opposed positions of a pair of bearing rings relatively making eccentric turning motion. SOLUTION: In this thrust ball bearing, and in a shape of orbit grooves 3 of a bearing ring 1, the groove depth (a) of the outer peripheral end 14 of a groove recessed part 13 is set same as the groove depth (b) of the inner peripheral end 14' of the groove recessed part 13 or larger than this. A cross-sectional shape of the groove recessed part 13 is constituted in a shape different in curvature in the same angle θ between normals viewed from one point P on the normals stood on the groove bottom (c) of the groove recessed part 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust ball bearing interposed between two members that relatively perform eccentric orbiting motion, such as a orbiting scroll member and a stationary scroll member in a scroll compressor.

[0002]

2. Description of the Related Art As a thrust ball bearing used in a scroll compressor, for example, one disclosed in Japanese Patent Application Laid-Open No. 10-89350 is known. As shown in FIGS. 4 (a) and 4 (b), the thrust ball bearing in this case is provided with a required number of annular rings at a constant pitch at opposing positions of a pair of bearing rings 1, 2 which relatively perform eccentric turning movements. The track grooves 3 and 4 are formed, and a ball 5 is interposed between the opposed track grooves 3 and 4.

The above-mentioned one orbital ring 1 is attached to a frame 8 fixed to a stationary scroll member 7, and the other orbital ring 2 is attached to the orbiting scroll member 6 so as to face the above-mentioned orbital ring 1. Can be

[0006] The orbiting scroll member 6 and the stationary scroll member 7 are provided with spiral partition walls 9 and 10 which fit into each other. The partition walls 9 and 10 and the scroll members 6 and
A compression chamber 11 is formed between the compression chamber 11 and the bottom plate 7.

[0005] An eccentric orbiting shaft 12 which rotates by an eccentric amount e is connected to the orbiting scroll member 6 described above. The groove bottom pitch circle diameter d of the track grooves 3 and 4 is set substantially equal to the eccentricity e. Each of the races 1 and 2 is usually formed by press molding.

[0006] The above-described thrust ball bearing supports the thrust load accompanying the compressing action, and the orbiting scroll member 6.
It has a function to prevent the rotation of

[0007]

FIG. 5 (a) is an enlarged view of the above-mentioned raceway ring 1, and a shoulder 15 is formed outside the outer peripheral end 14 of the groove recess 13 forming the annular raceway groove 3. FIG. A central projection 16 is formed inside the inner peripheral end 14 '.

The conventional groove shape is a part of a circle having the same curvature when viewed from both sides from a normal line on the groove bottom, or a part of an ellipse having a short axis parallel to the normal line. . The eccentricity e of the scroll member and the groove bottom pitch circle diameter d have a relationship of e ≧ d, and the ball rolls on the shoulder side of the raceway groove 3 to reduce the contact surface pressure and extend the life.

An elliptical contact mark on the raceway groove 3 generated by contact with the ball 5 under load is referred to as a contact ellipse. However, a design in which the contact ellipse runs over the shoulder portion 15 and the central convex portion 16 must be avoided. Must.

For this reason, it is effective to set the diameter d smaller than the eccentricity e in order to keep the deviation of the diameter d from the eccentricity e small and not to shorten the bearing life. There is a proposal. According to this method, the ball 5 rolls off to the shoulder 15 side of the raceway groove 3 and separates from the central convex portion 16 side, so that the contact ellipse A
Is prevented from riding on the central convex portion 16.

[0011] However, as shown in FIG.
If the pair of races 1 and 2 is misaligned, the ball 5 may roll not between the shoulders 15 but between the central convex portions 16 (see the contact ellipse B in FIG. 5A). The surface pressure is higher than in the case of rolling between the 15 members, which causes a short life of the bearing.

An object of the present invention is to reduce the contact ellipse by increasing the contact ellipse by decreasing the curvature of the groove concave portion constituting the raceway groove on the side of the central convex portion smaller than the curvature of the shoulder portion. It is to extend the life.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention forms a required number of annular race grooves at mutually opposing positions of a pair of race rings which perform a relatively eccentric turning movement. And a ball is interposed between the opposed raceway grooves,
In a thrust ball bearing in which the groove bottom pitch circle diameter of each of the track grooves is set smaller than the eccentric amount of the turning motion, the groove depth a of the outer peripheral end of the groove recess forming the track groove is determined by changing the groove depth of the groove recess. The groove depth b of the inner peripheral end was set to be equal to or larger than this, and the shape of the cross section of the groove recess was viewed from one point on the normal set on the groove bottom of the groove recess, and both sides of the normal were viewed. In this configuration, two points having the same angle have different curvatures.

The groove depth a at the outer peripheral end is set to a size such that the contact ellipse of the ball under load does not deviate outside the groove recess.

[0015] Further, the above-mentioned groove concave portion may be formed by a compound arc curve in which the curvature from the groove bottom to the outer peripheral end is larger than the curvature from the inner peripheral end, or the groove bottom within the range of the groove concave portion. It is possible to adopt a configuration formed by a part of an ellipse having a minor axis that intersects at a position other than.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The thrust ball bearing according to the embodiment is provided with a required number of annular race grooves 3 at a constant pitch at opposing positions of a pair of races 1 and 2 as in the conventional case.
4 is formed, and a ball 5 is interposed between the opposing raceway grooves 3 and 4.

The above-described thrust ball bearing is a conventional case (FIG. 4).
(See (a)), used in scroll compressors,
The bearing ring 1 is attached to a member integral with the stationary scroll member, and the bearing ring 2 is attached to the orbiting scroll member. The bearing ring 1 is eccentrically turned with respect to the bearing ring 2 by an eccentric amount e. The diameter d of the groove bottom pitch circle of the above-mentioned track grooves 3 and 4
Is set to a size smaller than the eccentricity e by a required amount (for example, 0 to 5%).

FIG. 2 is an enlarged view of a portion of the raceway groove 3 of one raceway ring 1, and shows an outer peripheral end 1 of a groove recess 13 of the annular raceway groove 3.
The groove depth at 4 is represented by a, and the groove depth at the inner peripheral end 14 'is represented by b. The outer peripheral end 14 is formed in the groove recess 1.
3 and an inflection point between the groove shoulder 15 and the inner peripheral end 1
4 ′ is an inflection point between the groove recess 13 and the central projection 16.

The groove depth a and the groove depth b are set to be equal or the former is set to be larger than the latter (that is, a ≧ b).
The size of the above-mentioned groove depth a is determined by the ball 5 under load.
Is set to a size that does not deviate outside the outer peripheral end 14 of the groove recess 13.

As the shape of the groove recess 13 (the shape between the outer peripheral end 14 and the inner peripheral end 14 '), there are shapes as shown in FIGS. 3 (a) and 3 (b). Generally speaking, the curvature is different at two points at the same angle θ when viewing both sides of the normal L from a point P on the normal L formed on the groove bottom c of the groove recess 13.

In the case of FIG. 3A, from the groove bottom c to the outer edge 14
Is an arc of curvature R, and a range from the groove bottom c to the inner peripheral end 14 'is an arc of curvature r (<R). Also, in the case of FIG.
3 is a shape formed by a part of an ellipse having a minor axis that intersects at a position other than the groove bottom c within the range of the groove bottom c.

Although the above description has been made with respect to one race 1, the same can be said of the other race 2.

With the above configuration, the ball 5 travels outside the groove bottom pitch circle with a diameter of the eccentricity e when the load is applied, but the groove depth a on the outer peripheral end 14 side of the groove recess 13 is reduced. Since it is formed relatively large, it is possible to prevent the contact ellipse A from deviating to the outside of the outer peripheral end 14.

[0024]

As described above, according to the present invention, the groove bottom pitch circle diameter d of a required number of annular race grooves provided on a pair of race rings which perform eccentric rotation is smaller than the eccentric amount e of eccentric rotation. In the case where the bearing life is extended by setting, the problem that the contact surface pressure increases due to the occurrence of misalignment and the like, and the ball rolling position is shifted toward the center convex side of the groove concave portion, has a problem that the contact surface pressure increases. The problem is solved by changing the curvature of the groove on the side of the central convex portion and the shoulder portion of the groove so that the central convex portion side is reduced. Therefore, according to the present invention, it is possible to prevent the life of the bearing from being shortened due to the occurrence of misalignment or the like.

[Brief description of the drawings]

FIG. 1A is a partially enlarged cross-sectional view of a thrust ball bearing according to an embodiment. FIG.

FIG. 2 is a partially enlarged cross-sectional view and a partially enlarged plan view of the thrust ball bearing of the embodiment.

3 (a) and 3 (b) are explanatory diagrams of the shape of a track groove.

FIG. 4A is a sectional view of a conventional example in use, and FIG.

5A is a partially enlarged cross-sectional view and a partially enlarged plan view of a conventional thrust ball bearing. FIG. 5B is a partially enlarged cross-sectional view of the same.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 raceway ring 2 raceway ring 3 raceway groove 4 raceway groove 5 ball 6 orbiting scroll member 7 stationary scroll member 8 frame 9 spiral partition 10 spiral partition 11 compression wall 12 eccentric rotation shaft 13 groove recess 14 outer peripheral end 15 inner peripheral end 16 central convex Department

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Jiro Iizuka F-term (reference) 3J101 AA02 AA42 AA53 AA62 BA55 FA31 GA29 in Sanden Co., Ltd. 20 Kotobukicho, Isesaki-shi, Gunma

Claims (4)

[Claims] A pair of orbital rings that perform relatively eccentric turning motions have a required number of annular orbital grooves formed at positions facing each other, and a ball is interposed between the opposing orbital grooves. In a thrust ball bearing in which the groove bottom pitch circle diameter of the raceway groove is set to be smaller than the eccentric amount of the above-mentioned swiveling motion, the groove depth a of the outer peripheral end of the groove concave part forming the above-mentioned raceway groove is defined by the inner periphery of the groove concave part The depth of the groove is set to be equal to or greater than the groove depth b at the end, and the cross-sectional shape of the groove recess is the same angle when viewing both sides of the normal from a point on the normal set to the groove bottom of the groove recess. 2
A thrust ball bearing having a shape having different curvatures at points. 2. The thrust ball bearing according to claim 1, wherein the depth a of the groove at the outer peripheral end is set to a size such that the contact ellipse of the ball under load does not deviate out of the groove recess. . 3. The groove according to claim 1, wherein the shape of the groove recess is formed by a compound arc curve in which the curvature from the groove bottom to the outer peripheral end is larger than the curvature from the inner peripheral end. Thrust ball bearing. 4. A groove according to claim 1, wherein the shape of the groove recess is formed by a part of an ellipse having a short diameter that intersects a position other than the groove bottom within a range of the groove recess. A thrust ball bearing according to item 1.