GB2310476A

GB2310476A - Tripot universal joint

Info

Publication number: GB2310476A
Application number: GB9603542A
Authority: GB
Inventors: Michel Jean Allain; Claude Alain Mosnier
Original assignee: Delphi Automotive Systems France
Current assignee: Delphi Automotive Systems France
Priority date: 1996-02-20
Filing date: 1996-02-20
Publication date: 1997-08-27
Anticipated expiration: 2016-02-20
Also published as: GB9603542D0; GB2310476B

Abstract

A tripot universal joint (10) comprises a substantially annular outer housing (16) connectable to a shaft and having three grooves (54) formed therein which extend longitudinally and a substantially annular inner race (18) having three longitudinal slots (30) positioned inside the outer housing and connectable to another shaft. A spider member (26) is positioned inside the inner race and has three trunnions (28) each extending radially through one of the slots and into one of the grooves. The spider member is pivotable relative to the inner race. A roller (34) is rotatable on each trunnion and slidable in the respective slot. A roller bearing (24) is positioned around each trunnion and within the respective groove and comprises balls (58) engageable with opposed surfaces of the respective groove (54) to allow the roller bearing and the spider member to translate in a longitudinal direction relative to the outer housing.

Description

TRIPOT UNIVERSAL JOINT This invention relates to a universal joint of the tripot type for the transmission of torque between two rotatable shafts. The present invention has particular application in motor vehicles, and in particular for providing drive to steerable driven wheels on a motor vehicle.

It is well known to provide a universal joint of the tripot type between two rotatable shafts.

A tripot joint typically comprises an outer housing or race connectable to one shaft, three radially extending trunnions connectable to the other shaft by way of a spider member which is splined to the other shaft, and rollers rotatable on the trunnions and axially slidable in channels in the outer housing. In such a tripot joint, numerous needle bearings are typically provided between each trunnion and its associated roller to provide the required stroking and angulation function between the two shafts. This arrangement has disadvantages in terms of the dynamic interaction between the stroking and angulation functions. Examples of prior art arrangements can be found in EP-A-0244064; EP-A-0279127; and EP-A-0290142.

The present invention is a modification of the tripot universal joint shown in GB-A-2283801.

It is an object of the present invention to provide a universal joint which overcomes the above disadvantages.

To this end, a tripot universal joint for transmitting torque between two rotatable shafts in accordance with the present invention comprises a substantially annular outer housing connectable to one of the shafts, the inner surface of the outer housing having three grooves formed therein which extend longitudinally; a substantially annular inner race positioned inside the outer housing and connectable to the other of the shafts, the inner race having three slots therein which extend longitudinally; a spider member positioned inside the inner race and having three trunnions each of which extend in a radial direction through one of the slots and into one of the grooves, the spider member being pivotable relative to the inner race; a roller ball rotatable on each trunnion and slidable in the respective slot; a roller bearing positioned around each trunnion and within the respective groove, each roller bearing comprising a plurality of balls engageable with opposed surfaces of its respective groove in the outer housing, the balls being rotatable to allow the roller bearing and the spider member to translate in a longitudinal direction relative to the outer housing.

The present invention provides the required stroking and angulation of a standard tripot universal joint, but minimises the interaction between these two functions by allowing the spider member to pivot relative the said other shaft, and allowing the spider member to easily translate relative to the outer housing. Compared to previously known designs, the present invention reduces the generation and transmission of vibrations.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a tripot universal joint in accordance with the present invention, with the shaft connected to the inner race being omitted and the longitudinal axes of the inner race and outer housing being substantially aligned; Figure 2 is a cross-section of the tripot universal joint of Figure 1 with the inner race being pivoted relative to the outer housing; Figure 3 is a cross-section on the line III-III of Figure 1; and Figure 4 is a cross-sectional view of an alternative arrangement for the grooves in the outer housing.

Referring to Figures 1 to 3, a tripot universal joint 10 in accordance with the present invention is usable for transmitting torque between two rotatable shafts 12, 14. The tripot universal joint 10 comprises a substantially annular or cylindrical outer housing 16 integrally connected to one shaft 12 by an end wall 17, and a substantially annular or cylindrical inner race 18 connected to the other shaft 14 by way of a splined connection 20. A C-clip 22 secures the connection between the other shaft 14 and the inner race 18 as is well known in the art. With this arrangement, the outer housing 16 and the shaft 12 are rotatable together about the longitudinal axis A of the shaft 12, and the inner race 18 and the other shaft 14 are rotatable together about the longitudinal axis B of the other shaft 14.

The inner race 18 is positioned inside the outer housing 16.

The tripot universal joint 10 further comprises a spider member 26 which is positioned inside the inner race 18, but which has three radially extending trunnions 28 which are substantially equidistantly spaced. The trunnions 28 extend through slots 30 formed in the inner race 18, and each is positioned at its free end 32 within a roller bearing 24. The slots 30 in the inner race 18 extend longitudinally substantially parallel to the longitudinal axis B of the other shaft 14. A roller ball 34 is positioned on each trunnion 28, is rotatable thereabouts and slidable thereon, and is in contact with the walls 36 which define the corresponding slot 30. With this arrangement the inner race 18 can pivot relative to the spider member 26, the roller bearing 24, and the outer housing 16.

Consequently, the shaft 12 can pivot relative the other shaft 14.

The spider member 26 has a part-spherical surface 38 either formed integrally thereon or defined by a button member 40 secured thereto. The part-spherical surface 38 makes contact with a corresponding concave surface 42 formed on the end 44 of the other shaft 14 or integrally formed on the inner race 18. A spring retaining clip 46 comprising three arms 47 and a central portion 50 is secured by the arms to the inner race 18 at its end 48 remote from the other shaft 14. The central portion 50 of the spring retaining clip 46 engages the spider member 26 on the opposite side 52 to the part-spherical surface 38 to bias the part-spherical surface into contact with the concave surface 42. This arrangement retains the spider member 26 in the inner race 18 but allows the relative pivotal movement between the spider member 26 and the inner race 18.The opposite side 52 of the spider member 26 is preferably identical to the part-spherical surface 38 for ease of assembly of the tripot universal joint 10, and so as not to restrict the relative pivotal movement.

The outer housing 16 has three internal grooves 54, formed therein. The grooves 54 extend longitudinally substantially parallel to the longitudinal axis A, with the opposed sides 56, 58 thereof preferably having arcuate or curved (concave) surfaces. The grooves 54 are substantially equidistantly spaced apart in a circumferential direction, with the trunnions 28 positioned substantially centrally within the grooves 54, as can be seen in Figure 3.

Each roller bearing 24 is located within one of the grooves 54 and comprises an outer cage 60, an inner bearing race 62, and a number of balls 64. The inner bearing race 62 has a centrally located aperture 66 within which the trunnion 28 is located. The inner bearing 62 has a circumferential surface 68 directed away from the trunnion 28 in a radial direction which is arcuate or curved (concave) . The balls 64 are located in engagement with the curved circumferential surface 68 of the inner bearing race 62 and are rotatable relative thereto. The balls 64 are also engageable with the curved surfaces 56, 58 of the respective groove 54 and are rotatable relative thereto.The outer cage 60 is shaped (that is, has curved ends 70 directed in the longitudinal direction of the respective groove 54) to retain the balls 64 in position, but to allow the balls to rotate relative thereto. With this arrangement the balls 64 are trapped between curved surface 68 and curved surface 56, between curved surface 68 and curved surface 58, and between curved surface 68 and curved ends 70.

However, the balls 64 are free to translate around the inner bearing race 62. Preferably, each trunnion 28 can rotate and translate within the aperture 66 relative to the respective roller bearing 24. Each roller bearing 24 has an axial length X which is less than the axial length Y of the outer housing 16. Each roller bearing 24 is retained in its respective groove 54 in the outer housing 16 by the end wall 17 and a retaining ring 80. This arrangement allows each roller bearing 24, the spider member 26, and the inner race 18 to translate relative to the outer housing 16 in a direction substantially parallel to the longitudinal axis A, to provide a telescopic relative movement between the shafts 12,14.

With the present invention, the rotational devices of the joint are substantially self-positioned to minimise the interaction between stroking and angulation of the joint. This has benefits in terms of minimising vibration. Although the surface 56, 58 are shown as curved, flat surfaces may be used, or flat surfaces 56', 58' with a curved channel 80 (within which the balls 64 can roll) therein may be used as shown in Figure 4. The curved surfaces 56, 58 can, if required, allow limited tilting of the roller bearings 24 on the trunnions 28.

Claims

Claims:

1. A tripot universal joint for transmitting torque between two rotatable shafts comprising a substantially annular outer housing connectable to one of the shafts, the inner surface of the outer housing having three grooves formed therein which extend longitudinally; a substantially annular inner race positioned inside the outer housing and connectable to the other of the shafts, the inner race having three slots therein which extend longitudinally; a spider member positioned inside the inner race and having three trunnions each of which extend in a radial direction through one of the slots and into one of the grooves, the spider member being pivotable relative to the inner race; a roller ball rotatable on each trunnion and slidable in the respective slot; a roller bearing positioned around each trunnion and within the respective groove, each roller bearing comprising a plurality of balls engageable with opposed surfaces of its respective groove in the outer housing, the balls being rotatable to allow the roller bearing and the spider member to translate in a longitudinal direction relative to the outer housing.

2. A tripot universal joint as claimed in Claim 1, wherein each roller bearing is rotatably and/or slidably mounted on its respective trunnion.

3. A tripot universal joint as claimed in Claim 1 or Claim 2, wherein the opposed surfaces of each groove have a concave configuration.

4. A tripot universal joint as claimed in Claim 1 or Claim 2, wherein the opposed surfaces of each groove are substantially flat with a longitudinally extending curved channel therein within which the balls can roll.

5. A tripot universal joint as claimed in any one of Claims 1 to 4, wherein each roller bearing comprises an inner bearing race having a circumferential surface with a concave configuration around which the balls can rotate.

6. A tripot universal joint as claimed in any one of Claims 1 to 5, wherein a retaining ring retains the roller bearing in its respective groove.

7. A tripot universal joint as claimed in any one of Claims 1 to 6, wherein the spider member is retained in the inner race by a spring retainer clip which clips to the inner race.

8. A tripot universal joint as claimed in Claim 7, wherein the spring retainer clip biases the spider member into contact with the inner race of the said other shaft.

9. A tripot universal joint as claimed in Claim 8, wherein the spider member has a part-spherical surface which contacts a corresponding concave surface on the inner race or an end of the said other shaft.

10. A tripot universal joint as claimed in Claim 9, wherein the part-spherical surface is defined by separate button member attached to the spider member.

11. A tripot universal joint substantially as herein described with reference to, and as shown in, the accompanying drawings.