GB2246835A

GB2246835A - Tripode universal joint

Info

Publication number: GB2246835A
Application number: GB9116561A
Authority: GB
Inventors: Norbert Hofmann; Friedhelm John; Hans-Heinrich Welschof
Original assignee: Loehr and Bromkamp GmbH
Current assignee: GKN Driveline Deutschland GmbH
Priority date: 1990-08-02
Filing date: 1991-08-01
Publication date: 1992-02-12
Anticipated expiration: 2011-08-01
Also published as: DE4024534A1; JPH06341447A; GB9116561D0; GB2246835B

Abstract

A tripode universal joint comprising an outer joint member (1) in the form of a sleeve having in its interior three axis- parallel recesses (2) with circumferentially opposed track pairs (3, 4), and an inner joint member having three arms (6) extending outwardly into the recesses of the outer joint member, each arm having a respective swivelling head (8) which is movable angularly on the arm and lengthwise thereof, and a plurality of rolling members (11, 12) engaging the swivelling heads and arranged so that a number of the rolling members in linear disposition engage each of the tracks in a guide groove (13, 14) thereof so that the swivelling heads are constrained to axial movement relative to the outer joint member at a fixed orientation relative therto, wherein the rolling members in each individual track are held in respective guide means (23, 24) providing a closed continuous path for the rolling members. <IMAGE>

Description

Title: Tripode Universal Joint

Description of Invention

This invention relates to a tripode type of universal joint, comprising an outer joint member in the form of a sleeve having in its interior three recesses extending parallel to the rotational axis of the joint member, each recess comprising a pair of tracks opposed circumferentially of the joint member to one another, and an inner joint member having three arms which extend outwardly into the recesses of the outer joint member, each arm carrying a respective swivelling head which is relatively movable angularly on the arm and lengthwise thereof, and a plurality of rolling members engaging the swivelling heads and arranged so that a number of the rolling members in linear disposition engage each of the tracks in a guide groove thereof so that the swivelling heads are constrained to axial movement at a fixed orientation and radial position relative to the outer joint member. Such a tripode joint will hereafter be referred to as a tripode joint of the kind specified.

Tripode joints in which annular rollers run on the arms and roll directly in the tracks in the outer joint member are known. To reduce friction between the rollers and the arms on which they are received, needle bearings have been interposed therebetween. In the case of plunging tripode joints where the tracks extend parallel to the rotational axis of the outer joint member, rotation of the joint in the articulated condition results in a mixture of sliding and rolling movements of the rollers relative to the tracks, as well as in movements radially of the joint of the needle roller bearings on the arms. The frictional resistance to such movements on all three arms of the joint causes the excitation of axial forces and vibrations. Another known form of tripode joint is called the Triplan joint and comprises rolling members disposed in cages extending axially of the outer joint member, supported by way of intermediate pieces on the arms of the inner joint member which have external part-spherical surfaces. The cages 1 i 1 2 are guided in the tracks of the outer joint member to move parallel thereto. In this case, too, rotation of a joint in the articulated condition leads to combined rolling and sliding movements between the rolling members and the intermediate pieces, with the disadvantages referred to above.

US 4,768,990 discloses a joint in which the arms of the inner joint member have external part-spherical surfaces and each carries a swivelling member to be angularly movable thereon, with needle roller elements rolling on the tracks of the outer joint member and supported on the swivelling member. A sheet metal cage surrounding the swivelling member is provided to hold the needle rolling elements. In this case, too, radial movement of the swivelling member relative to the tracks of the outer joint member takes place as sliding movement of the needle rollers relative to the tracks. This design of joint is extremely complicated.

JP-59-40016A discloses a joint of the kind specified wherein balls are held in continuous guiding means annularly enclosing the swivelling head. During rotation of the joint in the articulated condition, the balls on one side of each arm, when loaded with the joint transmitting torque, are subjected to full load in the direction of rotation and roll as the joint rotates. However, the balls on the opposite side of each arm, from which the load is partially removed, rest against at least one groove shoulder. The balls rolling in the fully loaded condition displace them around the swivelling head in the direction of the movement of the swivelling head in the outer joint member, and the result is that there are significant frictional forces causing excitation of vibration in the joint.

It is the object of the present invention to provide a tripode joint of the kind specified which is economical to produce and provides an improvement in respect of the exdtation of vibrations when the joint rotates in the articulated condition.

According to the invention, we provide a joint of the kind specified wherein the rolling members in each individual track are held in respective guide means providing a continuous closed path for the rolling members.

. 1 i i 1 i i i 1 1 1 1 i 1 1 i 1 i 1 1 3 If a joint according to the invention is articulated during rotation while transmitting torque, the balls on both sides of each swivelling head are able to roll. Because of the separate guiding means, there is no need to provide any returning or centring means for the balls. The same effect is achieved if an articulated joint rotates when not subject to torque, where despite indifferent contact of the balls with the tracks, accurate rolling of the balls is always ensured so that the resulting excitation of vibration is minimised.

There are several possible ways in which the required simultaneous angular movement and movement radially of the joint between each arm and its swivelling head may be accommodated. In a first embodiment, each arm may be cylindrical and carry a member thereon for relative movement radially of the joint, such member having an external part-spherical surface which engages an internal part-spherical recess in the respective swivelling head. In this way it is possible to ensure a large contact area between both the arm and intermediate member and between the intermediate member and swivelling head. Such a large contact area leads to low bearing pressures and optimisation of lubricating conditions.

In a second possibility, each arm may have a part-spherical surface, e.g. provided by a forming or pressing operation thereon, and the swivelling head have a cylindrical bore which fits on the part-spherical surface. An advantage of this design is that a number of components is reduced, while the tapering gap between the components provides good lubrication conditions.

For both the above mentioned designs, it is important that relative axial movement between the inner joint member and outer joint member, which is the significant movement as far as axial excitation of vibrations in the joint is concerned, occurs in the form of pure rolling movements on the part of rolling members guided in grooves.

According to a third possibility, each arm may have a head portion having a first pair of surfaces which are part-cylindrical about an axis extending tangentially and spaced from the rotational axis of the inner joint member, and 4 a second pair of surfaces which are part-cylindrical about an axis extending parallel to the rotational axis of the inner joint member, such part-cylindrical surfaces being in contact with end faces and lateral faces respectively of a rectangular recess in the swivelling head. Ile swivelling head is thus able to move radially and simultaneously about two axes relative to the arm.

The rolling members used may comprise balls or rollers, arranged in a line at each side of each swivelling head so that their centres He in one plane at each arm.

Two lines of rolling members may be disposed in two parallel lines on each side of each swivelling head, so that their centres lie in two planes at each arm. This measure permits rolling members of smaller size to be used.

The rolling members associated with each track may be guided to be movable in a closed path around the respective swivelling head. They may be held in a sheet metal or plastics cage.

In view radially of the outer joint member, each swivelling head may be of square, rectangular, or even oval shape with parallel Rank parts adjacent the tracks.

The invention will now be described by way of example with reference to the accompanying drawings, of which:

Figure 1 is a cross-section through part of a first embodiment of joint according to the invention; Figure 2 is a view on the line A-A of Figure 1; Figure 3 is a cross-section through part of a further embodiment of joint according to the invention; Figure 4 is a section on the line B-B of Figure 3.

Referring firstly to Figures 1 and 2 of the drawings, the joint there illustrated comprises an outer joint member 1 in the form of a hollow sleeve provided in its interior with three equally circumferentially spaced axially extending recesses 2. Each recess has a pair of opposed tracks 3, 4 facing one another in the direction circumferentially of the joint member. Within the outer 1 i i 1 1 i 1 1 1 1 joint member is disposed an inner joint member 5 which has three arms 6 spaced equally from one another about the axis of the inner joint member and extending radially outwardly into the recesses 2 in the outer joint member. Each arm 6 has a head portion 7 which has a part-spherical surface, guided within an internally cylindrical opening of a swivelling head 8. Each swivelling head is thus able to pivot universally on its arm 6, and to move lengthwise of the arm, i.e. radially of the joint as a whole, relative thereto.

The swivelling head 8 is provided on opposite sides with tracks 9, 10 which face guide grooves 13, 14 respectively provided in the tracks 3, 4 of the outer joint member. A plurality of rolling members, in this case balls 11, are provided engaging in the facing track 9 and guide grooves 13. Adjacent the facing track 9 and guide groove 13, the swivelling head is provided with guide means indicated generally at 23, comprising a pair of sheet metal dish-like elements 25, 26 secured by rivets 29 to the swivelling head. The guide means 23 provides a continuous closed path for a plurality of balls 11, around which path the balls can circulate as they roll along the facing track 9 and guide groove 13.

At the opposite side of the swivelling head, balls 12 are disposed in facing track 10 and guide groove 14, and constrained by guiding means 24 comprising sheet metal dish-like elements 27, 28 connected by rivets 30 to the swivelling head.

The sheet metal elements forming the guiding means have rail portions 35, 36, 37, 38 which constrain the rolling members in the guide grooves 13, 14.

Tbus the swivelling head is constrained to axial movement relative to the outer joint member at a fixed orientation relative thereto and a constant distance from the axis of rotation of the outer joint member. Low friction movement of the swivelling head relative to the outer joint member is provided whatever conditions of torque transmission prevail in the joint.

Referring now to Figures 3 and 4 of the drawings, these show a joint which has certain similarities of construction and operation to the joint of Figures 1 and 2, and therefore the same reference numerals are applied to parts of i i i 1 6 corresponding or analogous function or configuration. Thus, the joint of Figures 3 and 4 comprises an outer joint member 1 with circumferentially spaced recesses 2 having opposed tracks 3, 4. An inner joint member 5 has three radial arms 6 which extend into the recesses 2 in the outer joint member, and have part- spherical head portions 7 received in openings in swivelling heads 8. Each swivelling head 8 comprises oppositely facing tracks 9, 10, facing guide grooves 13, 14 in the tracks 3, 4 in the outer joint member, and balls 11, 12 are received in such facing tracks and guide grooves. The swivel heads 8 are of rectangular shape as viewed radially of the joint.

The outer joint member is provided with bores 31, 32 extending longitudinally thereof, parallel to and spaced from the guide grooves 13, 14. Sheet metal parts 33, 34 connected to the outer joint member extend in generally part-toroidal configuration to connect the bores to the guide grooves, and continue in rails 35, 36, 37, 38 extending along the guide grooves 13, 14, to define respective closed continuous paths for the balls 11, 12, with the balls filling such paths. The rails 35-38 hold the balls in the guide grooves in the portions thereof where they are not engaged by the swivelling head. Thus, when the swivelling head moves axially relative to the outer joint member, the balls circulate through such paths. Therefore, as in the embodiment of Figure 1, axial freedom of movement of the swivelling heads relative to the outer joint member is provided with minimal frictional resistance.

- Modifications in the configuration of the swivelling heads, the tracks and guide grooves, and the mode of engagement between the swivelling heads and the arms of the inner joint member, may be provided as above referred to.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

i 1 z 1 7

Claims

1. A tripode universal joint comprising an outer joint member in the form of a sleeve having in its interior three recesses extending parallel to the rotational axis of the joint member, each recess comprising a pair of tracks opposed circumferentially of the joint member to one another, and an inner joint member having three arms which extend outwardly into the recesses of the outer joint member, each arm carrying a respective swivelling head which is relatively movable angularly on the arm and lengthwise thereof, and a plurality of rolling members engaging the swivelling heads and arranged so that a number of the rolling members in linear disposition engage each of the tracks in a guide_ groove thereof so that the swivelling heads are constrained to axial movement at a fixed orientation and radial position relative to the outer joint member, wherein the rolling members in each individual track are held in respective guide means providing a continuous closed path for the rolling members.

2. A joint according to Claim 1 wherein the guide means are provided in association with the swivelling heads and include portions extending parallel to the guide grooves.

3. metal elements.

A joint according to Claim 2 wherein the guide means comprise sheet

4. A joint according to Clahn 2 or Claim 3 wherein the guide means are fixed to the swivelling heads.

5. A joint according to Claim 1 wherein the guide means are provided in the outer joint member and include portions extending parallel to the guide grooves.

8

6. A joint according to Claim 5 wherein the guide means comprise bores in the outer joint member.

7.

A joint according to any one of the preceding claims wherein the rolling members comprise balls.

8. A joint according o any one of Claims 1 to 6 wherein the rolling members comprise rollers.

9. A joint according to any one of the preceding claims wherein two or more parallel guide grooves are provided in each of the tracks in the outer joint member, the centres of the rolling members therein being guided in two or more parallel planes.

10. A joint according to any one of the preceding claims wherein, viewed radially of the joint, each swivelling head of the joint is of rectangular shape.

11. A joint according to any one of the preceding claims wherein the arms of the inner joint member each comprise a part-spherical head portion which engages a cylindrical opening in the respective swivelling head.

12. A joint according to any one of Claims 1 to 10 wherein the arms of the inner joint member are each cylindrical and carry a respective member thereon for relative movemen t radially of the joint, such member having an external part spherical surface which engages an internal part-spherical recess in the respective swivelling head.

13. A joint according to any one of Claims 1 to 10 wherein each arm has a head portion having a first pair of surfaces which are part-cylindrical about an axis extending tangentially and spaced from the rotational axis of the inner joint i i 1 1 i 1 1 1 9 member, and a second pair of surfaces which are part-cylindrical about an axis extending parallel to the rotational axis of the joint member, such part-cylindrical surface being in contact with end faces and lateral faces respectively of a rectangular recess in the respective swivelling head.

14. A joint substantially as hereinbefore described with reference to Figures 1 and 2, or Figures 3 and 4, of the accompanying drawings.

15. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.

1 Published 1992 at The Patent Office. Concept House. Cardiff Road. Newport. Gurent NP9 I Mi. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point. Cwinfelinfach. Cross Keys. Newport. NPI 7HZ. Printed ky Muluplex techniques lid. St Mary Cray. Kent-