GB2115523A

GB2115523A - Universal joints

Info

Publication number: GB2115523A
Application number: GB08304740A
Authority: GB
Inventors: Werner Krude
Original assignee: Uni Cardan AG
Current assignee: GKN Automotive GmbH
Priority date: 1982-02-23
Filing date: 1983-02-21
Publication date: 1983-09-07
Also published as: DE3206436C2; IT8207152V0; JPS58152934A; JPS6260567B2; IT8205262A0; FR2522096A1; GB8304740D0; IT1158484B; GB2115523B; DE3206436A1; FR2522096B1

Abstract

A universal joint comprises a first member 1 with an inwardly facing part circular groove 2 centred on the rotational axis 3 of the joint member, and a second joint member 5 affording a transverse bore 8 containing balls 4, 9 engaged in the groove 2. A further ball, a roller 10, or at least three smaller balls are disposed between the torque transmitting balls 4, 9 to facilitate rolling of the latter along the groove 2 when the joint is articulated. The first joint member affords a part-spherical guiding surface 18 engaged by the second joint member so that the torque transmitting balls are relieved of the necessity of centring the joint members relative to one another. Frictional resistance to joint articulation is thus minimal. <IMAGE>

Description

SPECIFICATION Universal joint This invention relates to a universal joint for torque transmission, comprising two joint members adapted to be joined to shafts or other rotary elements to be connected, with the first joint member affording a part circular groove whose centre line occupies a plane containing the rotational axis of the joint member and whose centre of curvature lies on such axis, and the second joint member having at least'two roller elmenets engaging diametrically opposed parts of the groove. Such a universal joint will hereafter be referred to as a universal joint of the kind specified.

One form of universal joint of the kind specified is disclosed in U.S. Patent Specification 1 763206.

In that joint, the roller elements comprise balls which occupy recesses on opposite sides of the second joint member. When the joint articulates, there is relatively high frictional resistance to sliding of the balls along the groove, which places high demands on lubrication of the joint. A more complex joint has been proposed in U.S. Patent Specification 1836095, which utilities an intermediate member somewhat in the shape of a star, and a large number of balls for torque transmission. However, this joint is complex and expensive to produce.

It is the object of the present invention to provide a joint of relatively simple, and thus economical, configuration, enabling relatively low friction to be achieved.

According to the invention, we provide a universal joint of the kind specified wherein the first joint member includes a part spherical guiding surface whose centre of curvature lies on the axis thereof, the second joint member has corresponding supporting engaging therewith, and the roller elements are disposed at opposite ends of a transverse bore in the second joint member wherein there is provided roller means between the roller elements to support same.

An advantage of such a joint arises from the guidance of the two joint members relative to each other by engagement between the part spherical guiding surface of the first joint member and the corresponding surfaces of the second member. The torque transmitting roller elements do not therefore have to take part in such guidance, and, because of the intermediate roller means between them, they can roll the groove in the first joint member when the joint articulates.

The inner joint member make comprise a tubular component providing said bore, held by its external surface by a supporting component. The joint thus utilises low cost components of simple design.

The torque transmitting roller elements may comprise balls whose diameter corresponds to the diameter of said bore, and the roller means may comprise a further ball of the same diameter disposed between them. Alternatively, at least three smaller balls may be disposed between them.

The use of a further ball or balls between the torque transmitting balls ensures that, when the joint is articulated, the torque transmitting balls roll in the correct relative direction, and can roll along the groove to produce minimal friction.

Alternatively, a roller may be disposed between the torque transmitting balls. Again, this provides for correct rolling of the balls when the joint articulates. To prevent high point contact loads between the balls and roller, the latter may have circumferetial groove of cross-sectional shape having a radius of curvature equal to the radius of the balls.

The invention will now be described by way of example with reference to the accompanying drawings, of which FIGURE 1 is a longitudinal section through one form of universal joint according to the invention, on the line B-B of Figure 2.

FIGURE 2 is a further section through the universal joint.

FIGURE 3 is a further section corresponding to Figure 2, but with the joint in the articulated condition.

FIGURE 4 is a section on the line A-A of Figure 2.

FIGURES 5 and 6 are sections corresponding to part of Figure 4, showing alternative components of the joint.

FIGURES 7 and 8 show the manner in which the universal joint can be assembled.

Referring firstly to Figures 1 2 and 3 of the drawings, the illustrated universal joint comprises a first joint member 1 rotatable about an axis 3.

This This joint member affords an inwardly facing part circular groove 2 whose centre line occupies a plane which also contains the axis 3, and whose centre of curvature in such plane lies on the axis 3.

The joint further comprises a second joint member 5 having a flange 6 for connecting it to a shaft, the joint member 5 taking the form of a yoke with spaced limbs which support a tubular member 7 extending transversly of the axis of rotation of the joint member 5. The tubular member 7 defines a bore 8, which contains two balls 4, 9 which engage in diametrically opposed parts of the groove 2 for torque transmission between the joint members. Between the balls is disposed a roller 10 which supports the balls, and facilitates their rotation in the same direction.

Around the groove 2, the joint member 1 affords a part spherical guiding surface 1 8 whose centre of curvature lies on the axis 3. The ends of tubular component 7 are correspondingly shaped, so that the joint members are always guided relative to one another such that their axes of rotation intersect. The torque transmitting balls thus do not take any part in such guiding.

The configuration of the joint member 5 supporting tubular member 7 is clearly shown in Figure 2 of the drawings.

In Figures 1 and 3, the joint is shown in the articulated condition. In Figure 1, the balls 4 and 9 have rolled along the groove 2 in the joint member 1, during which articulation the rolling of the balls has been facilitated by the intermediate roller 10.

In Figure 3, the joint member 5 has pivoted about the balls relative to the joint member 1, at an articulation angle indicated by arc 11. The kinematics of this joint correspond to those of a Hookes universal joint.

In the cross-section of Figure 4, the arrangement of balls 9 at opposite ends of the bore 8 provided by joint member 5 is clearly seen.

The flange 6 has bores 12 for receiving bolts by which it is secured to a shaft element. The roller 10 has a groove 1 3 whose cross sectional shape matches the curvature of the torque transmitting balls, so that high point loads between balls and roller are avoided. The ends of roller 14 are curved with a radius of curvature which matches the radius of the bore 8, so that the roller 1 0 can rotate within the bore 8.

As an alternative to the use of roller 10, a ball 1 5 of size equal to that of balls 9 may be used.

This is shown in Figure 5. As a further alternative, Figure 6, three or smaller balls 16 may be used between the torque transmitting balls.

To assemble the universal joint, the joint member 5 is introduced axially to the joint member 1, with its axis at right angles to the axis 3 of the joint member 1. Balls 9 and roller 10 can then be introduced into the tubular component 7, in the direction of axis 3. Thereafter, the joint member 5 can be moved angularly to its operative position whereupon it cannot be removed from the joint member 1.

Claims

1. A universal joint comprising two joint members adapted to be joined to shafts or other rotary elements to be connected, with the first joint member affording a part circular groove whose centre line occupies a plane containing the rotational axis of the joint member and whose centre of curvature lies on such axis, and the second joint member having at least two roller elements engaging diametrically opposed parts of said groove, wherein said first joint member includes a part spherical guiding surface whose centre of curvature lies on said axis, said second joint member has corresponding supporting surfaces engaging therewith, and said roller elements are disposed at opposite ends of a transverse bore in said second joint member wherein there is provided roller means between said roller elements.

2. A universal joint according to Claim 1 wherein said second joint member comprises a tubular component providing said bore and held by its external surface relative to a supporting component.

3. A universal joint according to Claim 1 or Claim 2 wherein said roller elements comprise balls of diameter corresponding to the diameter of said bore.

4. A universal joint according to Claim 3 wherein said roller means comprises a further ball of the same diameter as said balls.

5. A universal joint according to Claim 3 wherein said roller means comprises at least three smaller balls disposed between said balls.

6. A universal joint according to Claim 3 wherein said roller means comprises a roller disposed between said balls.

7. A universal joint according to Claim 6 wherein said roller has a circumferential groove of cross-sectional shape having a radius of curvature equal to the radius of said balls.

8. A universal joint substantially as hereinbefore described with reference to the accompanying drawings.