GB2102894A

GB2102894A - Bearings for hookes' joints

Info

Publication number: GB2102894A
Application number: GB08220522A
Authority: GB
Inventors: Miloslav Petrzelka; Herbert Taureg
Original assignee: Uni Cardan AG
Current assignee: GKN Driveline International GmbH
Priority date: 1981-08-08
Filing date: 1982-07-15
Publication date: 1983-02-09
Also published as: BR8203981A; IT8205183A0; IT8207021V0; ES272870Y; ES272870U; JPS5828018A; DE3131481A1; IT1157555B; FR2511097A1; SE8203330L

Abstract

A hookes universal joint wherein the bearing bushes 7 which support the journals of the cross-member in the yokes of the joint through needle rollers, or the bores in the limbs of the yokes, are chamfered to provide a gap between each bush and bore which increases with increasing distance from the centre of the cross-member. There may be two diametrically opposed chamfered portions 12 for each bearing bush or bore, of part- cylindrical form, and the plane containing the centre lines of the journals of the cross-member extends through the gaps defined by the chamfers. Alternatively the chamfers may extend around the entire circumference of the bearing bushes or bores. <IMAGE>

Description

SPECIFICATION Hookes universal joints This invention relates to a hookes universal joint, comprising two yokes each having spaced limbs with opposed aligned bores, and a crossmember having journals received in the bores of the yoke limbs, with the intermediary of bearing bushes, to connect the yokes for universal pivotal movement.

One problem which arises with hookes universal joints is that there is a tendency for uneven loading of the bearings supporting the journals of the cross-member during torque transmission. In a joint with needle rollers between the bearing bushes and journals, the load may not be evenly distributed along the lengths of the needle rollers. It has been proposed, in German Patent Specification 1,122,781, that the bearing surfaces of the journals or bushes can be tapered so that under conditions of slight distortion during torque transmission the needle rollers are evenly loaded. Whilst this is effective, it has the disadvantage that a tapered, frustoconical, surface is difficult to produce on the bearing surfaces of journals or bushes.It has also been proposed, in British Patent Specification 1,580,718, that the bearing surfaces of the journals or bushes can be ground to a slightly elliptical profile, so that the loading is shared between a greater number of needle rollers that would be the case otherwise. However, it is again difficult to manufacture such bearing surfaces.

It is the object of the present invention to provide a more economical way of achieving optimum utilization of the bearing capacity of a joint.

According to the present invention, we provide a hookes joint wherein at least part of the outer surface of each bearing bush or the inner surface of each bore is chamfered to provide a gap between each bush and bore, such gap increasing with increasing distance from the centre of the cross-member, and the plane containing the centre lines of the journals of the cross-member passing through such gaps.

By this means, the possibility of elastic deformation of the bearing bush is increased, so that the bearing bushes can be more evenly loaded during torque transmission.

There may be two diametrically opposite chamfered portions on each bearing bush or in each bore. Alternatively, there may be a continuous, preferably frusto-conical, chamfered surface extending circumferentially around each bush or bore.

When there are two diametrically opposed chamfered portions for each bush or bore, such chamfered portions may be part cylindrical in form. To ensure that the possibility of elastic deformation of the bearing bushes exists for the entire range of articulation angles of the joint, the invention provides that the circumferential extent of the chamfered portions for each bush or bore is at least double the maximum articulation angle of the joint, except when the chamfered portion extends around the entire circumference.

These and other features of the invention will now be described by way of example with reference to the accompanying drawings, of which: Figure 1 is a view of a drive-shaft having universal joints; Figure 2 is a section through a bearing bush of a universal joint according to the invention; Figure 3 is a plan of the bearing bush of Figure 2; Figure 4 is a section of part of one yoke of a universal joint according to the invention; Figure 5 is a plan view of the joint yoke of Figure 4.

Referring firstly to Figure 1, this shows a drive shaft having two shaft portions 1, 2 joined by a universal joint 3. The shaft portion 2 includes a splined section with a solid externally splined shaft portion 5 fitting within an internally splined tubular portion 6, to permit alteration in length of the shaft portion 2. At the other end of shaft portion 2 there is another universal joint. The universal joints comprise yokes with spaced limbs 8 having opposed bores therein, receiving journals of a cross-member 9.

The journals of the cross-member are received in the bores in the yoke arms with the intermediary of bearing bushes 7 with a cylindrical internal surface in which are received needle roller bearings, not shown. The bearing bushes are cup shaped, with end walls 13. As shown in Figures 2 and 3, the external surface of each bearing bush has a frusto-conical chamfered surface 12, which is of increasing depth with increasing distance from the centre of the cross-member, and extends axially of the bush for a distance 1 5 leaving a cylindrical portion of the external wall of the bush at its end which is innermost in the assembled joint.

In the plan of the bearing bush shown in Figure 3, the cylindrical outer surface of the bearing bush is shown at 11 and the frusto-conically chamfered surface at 12. 14 is the plane which contains the centre lines of the journals of the cross-member of the bearing.

Referring now to Figures 4 and 5, this shows an arm 8 of one of the yokes of a universal joint, with a bore 1 6 having a centre line 1 7. The bore has a frusto-conical chamfer 12 of very small apex angle, so that it is not cylindrical and a cylindrical sided bush received therein defines a circumferential gap which increases the distance from the centre of the cross-member of the joint.

By virtue of the provision of the chamfer on the external surface of each bearing bush, or within each bore, under torque loading each bush can be elastically deformed so that load on the needle roller bearings therein is evened out over their length. This enables optimum utilization of the theoretical bearing capacity of the joint.

The advantages of the invention may also be achieved if each bearing bush or bore is chamfered over part of its circumference only, such chamfered portion containing the plane of the centre lines of the journals of the crossmember. Since a universal joint typically is required to operate in both directions of rotation, each bush or bore preferably has two diametrically opposed chamfered portions, and the circumferential extent thereof around each bush or bore is preferably at least twice the maximum articulation angle of the joint.

The chamfered portions may be part cylindrical, and, if provided on the bushes, may have a radius of curvature greater than the radius of the unchamfered outer surface portion of the bush. If the chamfered portions are in the bores, they may be part cylindrical of a radius of curvature less than the radius of the unchamfered bore.

Claims

1. A hookes universal joint comprising a pair of yokes each having spaced limbs with opposed bores in which are received, with the intermediary of bearing bushes, journals of a cross-member to connect the yokes for universal pivotal movement, wherein at least part of the outer surface of each bearing bush or the inner surface of each bore is chamfered to provide a gap between the bush and bore, such gap increasing with increasing distance from the centre of the cross-member, and the plane containing the centre lines of the journals of the cross-member passing through such gaps.

2. A universal joint according to Claim 1 wherein said chamfered portion defines a continuous circumferential gap between each bearing bush and bore.

3. A joint according to Claim 1 wherein a chamfered portion is provided on opposite sides of the external circumference of each bearing bush.

4. A universal joint according to Claim 1 wherein a chamfered portion is provided on opposite sides of each bore.

5. A universal joint according to Claim 3 or Claim 4 wherein said chamfered portions are part frusto-conical.

6. A universal joint according to Claim 3 wherein said chamfered portions are partcylindrical, of a radius of curvature greater than the radius of the unchamfered outer surface of the bush.

7. A universal joint according to Claim 4 wherein said chamfered portions are part cylindrical of a radius of curvature less than the radius of the unchamfered bore.

8. A universal joint according to any one of Claims 3 to 7 wherein the circumferential extent of each chamfered portion of the bushes or bores is at least twice the maximum articulation of the joint.

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