GB2095369A

GB2095369A - Sealing universal joints

Info

Publication number: GB2095369A
Application number: GB8205292A
Authority: GB
Original assignee: Uni Cardan AG
Current assignee: GKN Automotive GmbH
Priority date: 1981-03-21
Filing date: 1982-02-23
Publication date: 1982-09-29
Also published as: GB2095369B; FR2502271A1; IT1157501B; BR8200898A; JPS57157825A; DE3111211C2; ES273310U; IT8205109A1; IT8205109A0; ES273310Y; DE3111211A1; JPS6129414B2; IT8206907V0

Abstract

A universal joint has an outer member 1, an inner member 2, and means for sealing between the members. The sealing means comprises a disc 10 of an elastic material, secured to the outer joint member 1 and having a central aperture whose free diameter is less than the diameter of a shaft 9 which is connected to the inner joint member. The disc material thus is stretched to fit the shaft 9, to provide a cylindrical portion 13 embracing the shaft and a transition portion 12, which together enable articulation and plunge of the joint without a gap appearing between the elastic disc and shaft. In another embodiment the disc engages a ring which has sealing lips that slidingly engage the shaft. <IMAGE>

Description

SPECIFICATION Universal joint This invention relates to means for establishing a sealing connection between the inner and outer member of a rotary constant velocity ratio universal joint, for retaining lubricant in the joint and excluding dirt therefrom.

The means which is used to seal between the outer and inner member of a universal joint is sub jest to the entire relative movement which occurs between the outer and innerjoint member. This relative movement comprises articulation, and, if the joint is a plunging joint, relative axial movement between the joint members.

A sealing means has been proposed, in German patent specification 336,487, which comprises a disc guided for radial movement in a groove in a rigid member which surrounds the universal joint. A shaft passes through an aperture in the centre of the disc.

However, only small angles of articulation are possible with this arrangement. The universal joint is a hookestype of universal joint, and not a constant velocity ratio joint. Lip seals which engage shafts are well-known, but are not suitable for use in connection with the universal joints, where articulation is involved.

It is an object of the present invention to provide an effective seal for a constant velocity ratio universal joint, which requires minimum space but permits relatively high rotational speeds and angles of articulation.

According to the invention, we provide a constant velocity ratio universal joint, comprising an outer member, an inner member, means for transmitting torque between said members, and means for establishing a sealing connection between said outer and inner joint members, such means comprising a disc of an elastic material secured to said outer joint member and having a central aperture through which a shaft part of or associated with said inner joint member extends, the free diameter of said aperture being less than the diameter of said shaft part.

By the free diameter of said aperture, we mean the diameter thereof when not stretched to have said shaft part fitted through it. This ensures that the disc fits sufficiently tightly to the shaft part to prevent loss of lubricant. The sealing means does not occupy much space axially of the shaft, as compared with a sealing gaiter or the like, and thus reduces to a minimum damage resulting from impact of stones or even gnawing damage caused by martens. If the joint is a plunging joint, plunge is permitted by the sliding of the disc along the shaft.

The material of the disc may be rubber or a plastics material. Such a disc may be manufactured by punching from a sheet of the material.

The disc may be secured to the outer joint member by a metal cap. This protects against escape of lubricant.

The diameter of the central aperture in the disc may be selected such that when fitted there is a cylindrical portion of the disc material embracing the shaft part, and a transition portion thereof.

The presence of a cylindrical portion and transition portion ensures that when the joint is articulated there is sufficient of the material of the disc to prevent a gap appearing between the shaft and disc. In the case of plunge of the joint, a certain amount is accommodated by deformation of the transition portion of the disc material, whereas greater plunging movement cause the disc material to slide on the shaft part.

The cylindrical part of the disc material may extend into the interior of the joint. Such part is then not subject to external influences such as ozone, ultra-violet rays, etc.

The invention will now be described by way of example with reference to the accompanying drawings, of which: Figure lisa section through a universal joint incorporating sealing means according to the invention; Figure 2 is a section through a slightly modified universal joint incorporating the invention; Figure 3 shows part of the universal joint of Figure 1 or Figure 2; Figure 4 is a sectional view of a further form of universal joint incorporating sealing means according to the invention; Figure 5 shows a modification of the joint of Figure 4; Figure 6 is a sectional view of a universal joint having yet a further form of sealing means according to the invention.

Referring firstly to Figure 1 of the drawings, there is shown a universal joint comprising an outer joint member 1 and an inner joint member 2 disposed within the hollow interior of the outer joint member.

The outer and inner joint members are provided with opposed axially extending grooves 5, 6, respectively, and each pair of grooves 5, 6 receives a ball 3 so that the joint members are connected for torque transmission. The balls 3 lie in apertures in an annular cage 4 disposed between the outer and inner joint members, the cage having a part spherical outer such face. The inner joint member 2 has a splined bore which receives a splined end portion 7 of a drive shaft 9, the shaft being held within the inner joint member by a securing ring 8.

A sealing connection is established between the outer and inner joint members at the end thereof from which the drive shaft 9 extends. A disc 10 of a elastic material such as rubber or a suitable plastics material is secured to the outer joint member by a metal cap 11, in such a manner as to prevent escape of lubricant. The disc 10 has a central aperture which in its free state is of smaller diameter than the diameter dl of the drive shaft. Thus the material of the disc adjacent its aperture is stretched when fitted to the shaft 9, so that there is formed a cylindrical portion 13 which embraces the shaft 9 and a transition portion 12 leading into the part of the disc 10 which extends radially. The length of the cylindrical portion 13 is determined by the size of the aperture in the disc.

In Figure 2 there is shown a universal joint with a sealing means which in principle is the same as that of Figure 1 with the diirc..c a 'n t Iindrcal portion 13 of the CiiSC m3 > 3i ial extends a:-;ay the interior of the joint instead of to\fE to as Eds in Figure 1.

When articulation of the joint occurs, the provision of the cylindrical portion 13 ensures that a gap does not open up between the elastic disc 10 and the shaft, to permit escape of lubricant or ingress of dirt.

For smail plunging movements, i.e. relative axial displacement between the inner and outer joint members, the transition portion 12 will be deformed, and for longer movements the cylindrical portion 13 will slide along shaft 9.

The disc 10 is shown in greater detail in Figure 3, with Figure 3a showing the disc in section and Figure 3b in plan. This shows the diameter d2 of the aperture 14 in the disc when not installed, which must be smaller than the diameter dl of the shaft. The outer diameter of the disc 10 corresponds approximately to the diameter of the outer joint member 1. The disc 10 is of a rubber or plastics material, and may be manufactured by punching from a sheet of such material.

Figure 4 shows a universal joint in which the sealing disc 10 engages the drive shaft associated with the inner joint member in the same manner as for the joint of Figure 2, with an outwardly turned cylindrical portion 13. However, fixing of the disc 10 to the outer joint member is effected by a steel ring 15 and clamping bolts. The disc 10 is provided with apertures 16 through which the clamping bolts extend. To ensure that the disc 10 is correctly held, intermediate packing rings 20 are utilized beneath the heads of the clamping bolts, and the axial dimension of the packing rings 20 may be obtained, for example, by adding the thicknesses of the steel ring 15 and elastic disc 10, minus 0.3 mm. Such an axial thickness of the packing rings 20, shown as dimension a in Figure 4, will ensure that the elastic disc 10 is compressed by 0.3 mm for proper sealing.

In Figure 5 there is shown an embodiment in which the disc 10 of elastic material has its cylindrical portion 13, of length L, turned inwardly to the interior of the universal joint. The disc 10 is secured to the outer joint member by a clamping ring 15, clamp bolts 18, and a spacer ring 17. The spacer ring spaces the disc 10 away from the joint so that the length L necessary for plunge of the joint can be accommodated towards the interior of the joint.

Figure 6 shows an embodiment similar two Figure 2, but in which the disc 10 engages a ring 19 slidable on the shaft 9, instead of directly on the shaft. The ring 19 is provided with sealing lips which engage the surface of the shaft.

Claims

1. A rotary constant velocity ratio universal joint, comprising an outer member, an inner member, means for transmitting torque between said members, and means for establishing a sealing connection between said outer and inner joint members, such means comprising a disc of elastic material secured to said outer joint member and having a central aperture through which a shaft part of or associated with said inner joint member extends, the free diameter of said aperture being less than the diameter of said shaft part.

2. A universal joint according to Claim 1 wherein said disc is of a rubber or plastic material.

3. A universal joint according to Claim 1 or Claim 2 wherein said disc is fixed to the outer joint member by a metal cap.

4. A universal joint according to any one of the preceding Claims wherein the free diameter of said aperture in the disc is such that there is a cylindrical portion of the disc material embracing said shaft part, and a transition portion of such material.

5. A universal joint according to Claim 4 wherein said cylindrical portion of the material of the disc extends towards the interior of the joint.

6. A universal joint according to Claim 4 wherein said cylindrical portion of the material of the disc extends away from the joint.

7. A universal joint according to any one of the preceding Claims wherein said disc engages said shaft part through the intermediary of a ring slidable on said shaft part.

8. A universal joint substantially as hereinbefore described with reference to and as shown in Figure 1, Figure 2, Figure 4, Figure 5 or Figure 6 of the accompanying drawing.