GB1600797A

GB1600797A - Universal joint sealing elements

Info

Publication number: GB1600797A
Application number: GB6312/78A
Authority: GB
Original assignee: Loehr and Bromkamp GmbH
Current assignee: GKN Driveline Deutschland GmbH
Priority date: 1977-02-25
Filing date: 1978-02-17
Publication date: 1981-10-21
Also published as: DE2708137C2; IT7707144U1; IT1090121B; FR2381951A1; FR2381951B1; DE2708137B1

Description

(54) IMPROVEMENTS IN OR RELATING TO UNIVERSAL JOINT SEALING ELEMENTS (71) We, LOHR & BROMKAMP GmbH, a Company organised and existing under the Federal Republic of Germany, of Postfach 166, 6050 Offenbach/Main 1 Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to means for sealing the bearings of a universal joint of the type hereinafter referred to as of the type described comprising relatively angularly movable members, a plurality of bearing bushes and a trunnion having stub arms, each stub arm extending axially into a respective one of said bushes, rollers being provided between each stub arm and the bush.

A sealing element is disclosed in British Patent Specification No. 1,559,113 which describes and claims a seal for the bearing between the cross piece stub arm and a yoke of a universal joint, the seal being of generally U shaped cross section having a first limb adapted to engage the yoke or bearing member received thereby, and a face on the stub arm extending perpendicular to the axis thereof, the second limb sealingly engageable with the stub arm and web portion interconnecting the first and second limbs and adapted to retain bearing elements in the bearing.

Difficulties arise since with such a seal unless the diameter of the face on the stub arm extending perpendicular to the axis of the stub arm is at least as great as the internal diameter of the bush or the stepped surface formed therein, the axial support provided by the sealing element may not be adequate.

In some cases it is required that such a face or shoulder around the stub arm should have a diameter less than the internal diameter of the bush.

It is an object of the present invention to provide a universal joint having a plurality of sealing elements that overcomes or reduces that above mentioned problem and in addition provides a labyrinth seal which can ensure effective sealing action relative to the trunnion even if the diameter of the stub arm shoulder is less than the internal diameter of the bush.

According to the present invention we provide a universal joint of the type described including a plurality of elastomeric sealing elements, each sealing element comprising a first part located in the respective bush and providing axial support for the rollers, the first part having a circumferential outer surface engaging the bush, a second part extending axially from the first part and having a circumferential outer surface spaced radially inwardly from the circumferential outer surface of the first part, the second part having a radially inwardly directed sealing lip circumferentially embracing the stub arm and having a portion extending axially beyond the sealing lip for engagement with a supporting surface on the trunnion substantially normal to the stub arm axis.

Preferably the portion of each sealing element that extends axially beyond the sealing lip for engagement with the supporting surface on the trunnion is the only portion of the sealing element that engages a surface on the trunnion substantially normal to the stub arm axis.

Such a sealing element is suitable for deepdrawn bushes or joint yoke liners which do not normally include outer step or shoulder formations.

The sealing element is fully protected against external influence even during assembly. The part of the sealing element which engages with the walls of the bore wherein it is received serves to support and secure the element in the bush or liner. By contrast, the inwardly situated limb of the element carries the actual sealing lip and the extension of this limb not only provides support for the sealing element but also forms an antechamber to keep out coarse dirt. The lubricant between the sealing lip and the antechamber keeps the sealing lip permanently lubricated so that it cannot run dry. The cushion of lubricant further protects the bearings against moisture penetration.

The sealing element also provides support and hold for the rollers. Since this supporting function is assigned to the inwardly situated limb of the sealing element, the latter may also be used in situations where the diameter of the shoulder radius of the stub arms is less than the internal diameter of the bearing bush. No sheet metal parts are required for securing purposes.

Arising from its special configuration the sealing element presents the advantage of being capable of being produced with the aid of a simple two part tool such as an injection mould thereby allowing the use of hard wearing elastomeric materials for example polyethylene, polyamide, polyurethane.

According to a further provision of this invention the sealing element may be accomodated in a step in the bush. This ensures a very precise seal between the bearing bush and the sealing element. In view of the latter being introduced into the step in the bush under force there is hardly any risk of lubricant escaping at this point to the exterior. Consequently the lubricant is forced to flow past the sealing lip which means that there is no danger of "running dry".

The sealing element may be substantially U configuration, comprising a second limb for secure engagement in the step of the bearing bush. This additional limb is adapted to be securely retained in the bush or in the bore step by virtue of its special form or shape, for example the exterior surface thereof may be tapered, the exterior surface may have a larger external diameter than the internal diameter of the bush or step therein, thus ensuring a press-fit of the sealing element relative to the bush or bore and thus providing a particularly advantageous means of fixation.

The sealing element prevents unduly high pressure arising from, or during greasing.

The extension part of the limb which engages with a bearing surface on the trunnion piece is provided with recesses or cut outs. This allows the lubricant to advance during the greasing operation without opposing pres sure from the bearing interior into the antechamber past the sealing lip which subsequently springs back to its former position. This permanently open channel and the low resistance offered by the sealing lip together prevent internal pressure build up which could create additional stress loads for the joint.

The arrangement also enables visual control during the greasing process to ensure that all stub arms are evenly and adequately supplied with lubricant.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings wherein: FIGURE 1 shows a cardanshaft with universal joints at both ends thereof.

FIGURE 2 shows a universal joint, in section taken in the plane of the stub arms, FIGURE 3 is a section along A-A in Figure 1, FIGURE 4 is an axial section of stub arm with needle bearings, bearing bush and sealing element, FIGURE 5 shows a sealing element basically as in Figure 4 but not requiring a step or shoulder in the receiving bore for its securing, FIGURE 6 shows a sealing element of substantially L-configuration.

The cardanshaft shown in Figure 1 comprises two co-axial shaft ends I and 2, each fitted with a universal joint 3, 4 at its outer end. The inner end of shaft 1 is a solid shaft end 5 whilst the cgrresponding end of shaft 2 is a hollow shaft end 6. The solid shaft end 5 and hollow shaft end 6 are relatively nonrotatably but axially slidably connected by splining 7.

Figures 2 and 3 illustrate a universal joint whereof the main body of the trunnion is shown at 8, bearing bushes 11 and 12 are arranged on each of the four stub arms 9 and 10 and the associated yokes being shown at 13 and 14. The trunnion body 8 is a forging.

The bearing bushes 11, 12 are received in bores of the yokes 13 and 14. Through the stub arms 9, 10 of the trunnion 8, lubrication bores 17 are formed which bores all connect with a central cavity 18. This cavity 18 is closed by a grease nipple 19. During greasing any excess of lubricant may escape outwards past the sealing element 20, but no dirt or water can enter from the outside into the bearing interior.

The sealing element 20 shown in Figure 4 comprises a first part having a limb portion 21 which engages the stepped surface 16 of the bearing bush 11, 12 and web part 25 having an end face 26 which gives support to the bearing rollers 27, and a second part 23 which is provided with a sealing lip 24.

The sealing lip 24 sub-divides the interior of the bearing cavity into two lubricant chambers 28 and 29.

The stored lubricant in these two chambers prevents the sealing lip running dry because the sealing lip 24 is permanently surrounded by lubricant. Any water or dirt which may have penetrated from the outside will collect in the antechamber 29 and cannot enter into the actual bearing interior 28.

The seal 20 is fitted and secured in place simply by being firmly pressed into the step 16 in the bearing bush 11 or 12; consequently the seal 20 is protected against damage during transport and assembly. In the course of a greasing operation the lubricant which advances past the bearing rollers 27 into the chamber 28 is forced past the sealing lip 24 into the antechamber 29 whence any excess lubricant may escape to the outside through openings 22 in the extension part 30 of the limb 23. Once the lubricant has moved on, the sealing lip 24 springs elastically back to its former position. The openings 22 are spaced over the circumference of the limb 23.

Figure 5 shows a modified seal element 29 which is basically the same as that shown in Figure 4 modified in that, instead of being fitted in a step, the limb 21 is here press fitted directly into the walls 31 of the bearing bush 11, 12. This form of execution is primarily applicable to deep-drawn bearing bushes.

Figure 6 shows yet another embodiment of the invention wherein a seal 20 is provided which is also press fitted in a step 16 as in Figure 4. However, this seal element 20 has a single limb portion 23 and has a wider or strengthened web portion 25. The actual sealing lip 24 corresponds to the earlier described forms of execution.

WHAT WE CLAIM IS: 1. A universal joint of the type described including a plurality of elastomeric sealing elements, each sealing element comprising a first part located in the respective bush and providing axial support for the rollers, the first part having a circumferential outer surface engaging the bush, a second part extending axially from the first part and having a circumferential outer surface spaced radially inwardly from the circumferential outer surface of the first part, the second part having a radially inwardly directed sealing lip circumferentially embracing the stub arm and having a portion extending axially beyond the sealing lip for engagement with a supporting surface on the trunnion substantially normal to the stub arm axis.

2. A universal joint of the type described wherein the portion of the second part extending axially beyond the sealing lip for engagement with a supporting surface on the trunnion substantially normal to the stub arm axis is the only portion of said sealing element which engages the surface of said trunnion substantially normal to the stub arm axis.

3. A universal joint of the type described as claimed in claim I or claim 2 wherein the bush is stepped and the sealing element engages the surface of the step.

4. A universal joint of the type described as claimed in any one of the preceding claims wherein the sealing element is of substantially U configuration, the first part comprising the inter connecting part between the two limbs of the U and the outer limb of the U which is adapted to engage with the inner surface of the bush.

5. A universal joint of the type described as claimed in any one of the preceding claims wherein the surface of said extended portion of each sealing element which engages with a supporting surface on the trunnion is discontinuous.

6. A universal joint of the type described including a plurality of sealing elements substantially as hereinbefore described with reference to and as illustrated in Figures 2, 3, 4 and 5 of the accompanying drawings.

7. A universal joint of the type described including a plurality of sealing elements substantially as hereinbefore described with reference to and as illustrated in Figure 6 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

16 in the bearing bush 11 or 12; consequently the seal 20 is protected against damage during transport and assembly. In the course of a greasing operation the lubricant which advances past the bearing rollers 27 into the chamber 28 is forced past the sealing lip 24 into the antechamber 29 whence any excess lubricant may escape to the outside through openings 22 in the extension part 30 of the limb 23. Once the lubricant has moved on, the sealing lip 24 springs elastically back to its former position. The openings 22 are spaced over the circumference of the limb 23.

Figure 5 shows a modified seal element 29 which is basically the same as that shown in Figure 4 modified in that, instead of being fitted in a step, the limb 21 is here press fitted directly into the walls 31 of the bearing bush 11, 12. This form of execution is primarily applicable to deep-drawn bearing bushes.

Figure 6 shows yet another embodiment of the invention wherein a seal 20 is provided which is also press fitted in a step 16 as in Figure 4. However, this seal element 20 has a single limb portion 23 and has a wider or strengthened web portion 25. The actual sealing lip 24 corresponds to the earlier described forms of execution.

WHAT WE CLAIM IS: 1. A universal joint of the type described including a plurality of elastomeric sealing elements, each sealing element comprising a first part located in the respective bush and providing axial support for the rollers, the first part having a circumferential outer surface engaging the bush, a second part extending axially from the first part and having a circumferential outer surface spaced radially inwardly from the circumferential outer surface of the first part, the second part having a radially inwardly directed sealing lip circumferentially embracing the stub arm and having a portion extending axially beyond the sealing lip for engagement with a supporting surface on the trunnion substantially normal to the stub arm axis.
2. A universal joint of the type described wherein the portion of the second part extending axially beyond the sealing lip for engagement with a supporting surface on the trunnion substantially normal to the stub arm axis is the only portion of said sealing element which engages the surface of said trunnion substantially normal to the stub arm axis.
3. A universal joint of the type described as claimed in claim I or claim 2 wherein the bush is stepped and the sealing element engages the surface of the step.
4. A universal joint of the type described as claimed in any one of the preceding claims wherein the sealing element is of substantially U configuration, the first part comprising the inter connecting part between the two limbs of the U and the outer limb of the U which is adapted to engage with the inner surface of the bush.
5. A universal joint of the type described as claimed in any one of the preceding claims wherein the surface of said extended portion of each sealing element which engages with a supporting surface on the trunnion is discontinuous.
6. A universal joint of the type described including a plurality of sealing elements substantially as hereinbefore described with reference to and as illustrated in Figures 2, 3, 4 and 5 of the accompanying drawings.
7. A universal joint of the type described including a plurality of sealing elements substantially as hereinbefore described with reference to and as illustrated in Figure 6 of the accompanying drawings.