JP2007271040A - Fixed type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed type constant velocity universal joint for reducing the contact bearing pressure of a ball on a guide groove. <P>SOLUTION: The sectional shape of at least one of guide groove 2, 5 of inner and outer rings 3, 6 of the constant velocity universal joint is constituted by a plurality of partial ellipses A-D, E-H connected to one another via at least three folding points. Thus, at least one of the guide grooves 2, 5 of the inner and outer rings has contact with the ball 7 at its four points or more to reduce the bearing pressure of the contact face of the ball. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a fixed type constant velocity universal joint used for automobiles and various industrial machines.

The guide groove shape of a conventional barfield type constant velocity joint in which the ball rolls in a plurality of guide grooves is an angular contact shape composed of a part of an ellipse in which the ball contacts the inner ring and the outer ring at two points ( AC) is common. As another example of the guide groove shape, there is a combination of a curve and a straight line so that the ball contacts the inner ring and the outer ring at three points. In addition, there are a total of five contact points between the ball and the guide groove, that is, three points for the inner ring guide groove and two points for the outer ring side guide groove (see, for example, Patent Document 1).
German Patent Publication DE 196 33 216 C1

As for the conventional guide groove shape of the inner and outer rings, the contact point of the ball is at most three as in Patent Document 1. For this reason, the contact surface pressure with a ball | bowl is comparatively high, and the fatigue and peeling by a repetitive load arise, and there existed a possibility of causing the fall of durability.
In view of such circumstances, the present invention provides a novel inner and outer guide groove shape that reduces the contact surface pressure with the ball.

  In order to solve the above problems, the invention of claim 1 is directed to an outer member in which a plurality of guide grooves are formed on the inner spherical surface along the axial direction in the circumferential direction, and a guide groove of the outer member on the outer spherical surface. Torque is transmitted by interposing an inner member in which a plurality of paired guide grooves are formed along the axial direction in the circumferential direction, and between the guide groove of the outer member and the guide groove of the inner member. A fixed type constant velocity universal joint comprising a plurality of balls and a cage for holding the balls interposed between an inner spherical surface of the outer member and an outer spherical surface of the inner member. It is characterized in that at least one guide groove of the guide groove of the member has a groove shape that contacts the ball at four or more points. As an example of the cross-sectional shape of such a guide groove, a groove shape constituted by a plurality of partial ellipses connected via at least three bending points is proposed. In this way, by forming at least one guide groove in the shape of a guide groove that makes contact with the ball at four or more points, the load on the guide groove at the contact point with the ball can be dispersed, and the surface per contact point The pressure can be reduced. This can reduce the occurrence of fatigue and peeling due to repeated loading of the guide groove, and improve the durability of the fixed type constant velocity universal joint.

In the present invention, since the guide groove of at least one of the guide grooves of the outer member and the inner member has a groove shape that contacts the ball at four or more points, the guide groove load at the contact point with the ball is dispersed. And the surface pressure per contact point can be reduced. Thereby, the occurrence of fatigue and peeling due to repeated loading of the guide groove can be reduced, and the durability of the fixed type constant velocity universal joint can be improved.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. The fixed type constant velocity universal joint of FIG. 1 is a bar field type, and an outer ring 3 as an outer member in which a plurality of guide grooves 2 are formed on the inner spherical surface 1 at equal intervals in the circumferential direction, An inner ring 6 as an inner member in which a plurality of guide grooves 5 paired with the guide groove 2 of the outer ring 3 are formed in the outer spherical surface 4 along the axial direction at equal intervals in the circumferential direction, and the guide groove 2 of the outer ring 3 A plurality of balls 7 which are interposed between the guide grooves 5 of the inner ring 6 and transmit torque, and a cage 8 which is interposed between the inner spherical surface 1 of the outer ring 3 and the outer spherical surface 4 of the inner ring 6 and holds the balls 7. And. The plurality of balls 7 are accommodated in pockets 9 formed in the cage 8 and arranged at equal intervals in the circumferential direction. The present invention is not limited to the bar field type and can be applied to other types of fixed constant velocity universal joints including an undercut free type.

This fixed type constant velocity universal joint, to a structure capable of having a large operating angle, and a curvature center O ₂ of the guide groove 5 of the center of curvature O ₁ and the inner ring 6 of the guide grooves 2 of the outer ring 3, the ball center O The joint center plane P is offset in the axial direction by an equal distance f. By providing the track offset in this way, each of the guide grooves 2 and 5 is shallow from the axial center to the bottom side of the outer ring and deep at the opening side of the outer ring, and as a result, from the bottom side of the outer ring 3. A wedge-shaped ball track in which the radial interval gradually increases toward the opening side is formed.

  When this type of constant velocity universal joint is used for, for example, a drive shaft of an automobile, the outer ring 3 is connected to a driven shaft, and a drive shaft extending from a sliding type constant velocity universal joint attached to the inner ring 6 on a differential on the vehicle body Are connected by spline fitting. In this constant velocity universal joint, when an operating angle is provided between the outer ring 3 and the inner ring 6, the ball 27 accommodated in the cage 8 is always within the bisector of the operating angle at any operating angle. It is maintained and constant velocity of the joint is ensured.

The outer ring 3 and the inner ring 6 constituting a part of the constant velocity universal joint of this embodiment are each a single unit having the above-mentioned curvature centers O ₁ and O ₂ in the cross section along the axial direction on each of the inner spherical surface 1 and the outer spherical surface 4. It has a structure in which guide grooves 2 and 5 having one circular arc shape are formed. FIG. 2 is a cross-sectional view showing the guide groove 2 formed on the inner spherical surface 1 of the outer ring 3 and the guide groove 5 formed on the outer spherical surface 4 of the inner ring 6. As shown in the figure, the cross-sectional shape of each guide groove 2, 5 has four partial ellipses AD formed by machining or cold forging with a radius of curvature R larger than the radius r of the ball 7. It is comprised by the combination of ~ H. The partial ellipses A and B on the right side of the outer ring 3 and the partial ellipses C and D on the left side are symmetrical with respect to the guide groove center line. Similarly, the right partial ellipses G and H and the left partial ellipses E and F of the inner ring 6 are symmetrical with respect to the guide groove center line. The partial ellipses A to D and E to H are connected at a bending point. The ball 7 comes into contact with each other at the contact point in the center in the width direction of these partial ellipses AD.

That is, the ball 7 is in contact with the four points (a, b, c, d) of the guide groove 2 of the outer ring 3, and the ball 7 is in contact with the four points (e, f, g, h) of the guide groove of the inner ring 6. The ball 7 and the guide grooves 2 and 5 are in contact with the contact angle α from the track center line at points b, c, f, and g, and at the contact angle β at points a, d, e, and h. The four partial ellipses A to D or E to H constitute the guide grooves 2 and 5, and the curvature radii R of the partial ellipses A to D and E to H are the same as the conventional ones. As a result, the ball contact rate (R / r) is equivalent. (R is the radius of the ball).
In this embodiment, the contact point between the inner and outer rings 3 and 6 and the ball 7 is doubled as compared with the conventional Gothic arch-shaped guide groove that makes an angular contact with the ball 7 at two points. As a result, the surface pressure per contact point can be reduced, fatigue due to repeated load and occurrence of peeling can be reduced, and the durability of the fixed type constant velocity universal joint is improved. Further, the curvature radius R is not necessarily equal, and may be changed within a range in which the surface pressure can be reduced as compared with the conventional one.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above embodiment, both the inner and outer rings have four points on the ball 7, but only one of the inner and outer rings is in contact with the ball 7 at four points or more, and the other is in contact with less than four points. May be. Further, the ball 7 may be brought into contact with any of the inner and outer rings at four or more points.

The longitudinal cross-sectional view of the fixed type constant velocity universal joint which concerns on this invention. The cross-sectional view of the inner and outer ring guide grooves of the fixed type constant velocity universal joint according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner spherical surface 2, 5 Guide groove 3 Outer ring 4 Outer spherical surface 6 Inner ring 7 Ball 8 Cage 9 Pockets A to D Partial ellipse E to H Partial ellipse

Claims (2)

  An outer member in which a plurality of guide grooves are formed on the inner spherical surface along the axial direction in the circumferential direction, and a plurality of guide grooves that are paired with the guide grooves of the outer member on the outer spherical surface in the circumferential direction. An inner member formed along the outer member, a plurality of balls which are interposed between the guide groove of the outer member and the guide groove of the inner member, and transmit the torque, and the inner spherical surface and the inner member of the outer member A fixed type constant velocity universal joint provided with a cage that is interposed between an outer spherical surface of an outer member and holds the ball, wherein at least one guide groove of the outer member and the inner member is provided with respect to the ball. A fixed type constant velocity universal joint characterized by having a groove shape that contacts at least four points.   2. The fixed type constant velocity universal joint according to claim 1, wherein a cross sectional shape of the guide groove is constituted by a plurality of partial ellipses connected via at least three bending points.

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