GB2216631A

GB2216631A - Telescopic universal joint shaft

Info

Publication number: GB2216631A
Application number: GB8905932A
Authority: GB
Inventors: Reinhard Bretzger
Original assignee: JM Voith GmbH
Current assignee: JM Voith GmbH
Priority date: 1988-03-22
Filing date: 1989-03-15
Publication date: 1989-10-11
Anticipated expiration: 2009-03-15
Also published as: FR2629156B1; GB2216631B; FR2629156A1; DE8816516U1; GB8905932D0; JPH01283434A

Abstract

The invention relates to a telescopic universal joint shaft of a particularly short design. This is achieved by the joint halves (2, 4, 12, 14) being disposed radially inside one another and being connected to one another via an annular intermediate element (3, 13). As a result space is created for a length adjustable part (5), which requires a particularly short overall length in a tripod adjustment mechanism (6) therefor. The invention provides a universal joint shaft which is particularly short, is suitable for high torques and has a length adjustment with low shearing strength. Such a shaft is particularly suitable for drives in tracked vehicles. <IMAGE>

Description

A Telescopic universal-joint The invention relates to a universal-3oint shaft having a length-adjustable shat part and also two universal joints, which respectively consist of two joint halves connected via an intermediate element. A universal-joint shaft of this type is known from German Offenlegungsschrift 28 09 665 (U.S. Specification 4271 685).

The universa-joint shafts used in motor vehicles normally have to bridge a r=-latively great distance, e.c. between the gearing and the driving axle. At the same time it is usually necessary to compensate for height variations and changes in Fosition during operation by varying net loads and the play of the spring. As a result the joints have to be exposed to great angles of fiexure and length adjust- ment. This results in joints and shafts having great axial overall length. There is usually adequate space for such shafts. Difficulties arise particularly if large joint diameters also have to be taken into consideration for high torques.

In special cases, e.g. with the drive of tracked vehicles, the conditions regarding space are different. Usually there is only a short mounting length available for the universaljoint shaft, whereas a greater joint diameter does not cause any problems with respect to space. A typical application is the drive of a wheel set in a transverse traction motor. In this case the important factors are the relatively slight angle of flexure in operation, the high torque load and the axial length adjustment under load.

These requirements are not met by the universal-joint shafts normally used in the construction of motor vehicles.

In particular the length adjustment mechanism constructed as a splined shaft is very susceptible to friction and does not offer the expected durability and reliability. With the known universal-joint shaft a reduction in length has already been achieved, but the joint bearings and ' the length adjustment mechanism of the design chosen are weak.

The object of the invention is to create a short universaljoint shaft suitable for high torques in continuous operation with a small maximum angle of flexure, with the length adjustment mechanism also having a low resistance under load.

This object is achieved in accordance with the characterising features of Claim 1 in that a joint design is chosen with which the joint halves are not moved apart in the axial direction, but are disposed radially inside one another. The intermediate element connecting the joint halves is constructed as a circle and is connected radially outwards with one joint half and radially inwards with the other joint half. The length adjustment mechanism is constructed, as is per se alone known, in a tripod design with roller elements which connect a shaft part and and hub part to one another in a form-locking way.

With this combination of features there is obtained a universal-joint shaft with a particularly short overall length, because the joints only occupy as small space axially and give room for the arrangement of the length adjustment mechanism partly inside the joint itself. The length adjustment mechanism using roller elements requires less overall length than a splined shaft of equal bearing strength and has the advantage of low axial reaction forces on the bearings of the drive components to be connected (motor, gears). The slight overall length of the joints and of the length adjustment mechanism results in a minimal total length using the radial space available.

Further refinements of the invention are given in the subordinate claims.

An exemplified embodiment of the invention is described in more detail below with reference to the drawings.

Figure 1 shows a longitudinal section through a univer sal joint shaft through the region of the joint bearings; Figure 2 shows a cross section through the shaft joint; Figure 3 shows a cross section through the second joint in the region of the bearings and roller bod ies.

Figure 1 shows a universal joint shaft having two universal joints 1 and 11, which are connected to other drive components (not shown). Each joint 1, 11 consists of a first joint half 2, 12 and a second joint half 4, 14. which are connected to one another via an intermediate element 3, 13. The second joint half 4 of one joint 1 is continued in a central shaft part 5 with a stub shaft 7. The second joint half 14 of the other joint 11 is continued in a hub part 8, which surrounds the stub shaft 7 in a tubular shape. Between the hub part 8 and the stub shaft 7, there are rollers 9, which are supported on bolts 10 preferably via roller bearings and are jointly secured in the stub shaft 7. Three rollers 9 are preferably provided, and they engage in radial grooves 15 with axial extensions on the inside of the hub part 8 and. produce a form-locking axially movable rotating connection.On the front side of the hub part 8 nearer to the first joint 1 there is a centering bush 16 for guiding the hub part 8 on the shaft 5. This centering bush, which is important for achieving adequate bending strength and smooth running, also has a seal 17 and can serve as an end stop for the longitudinal displacement of the rollers 9 to one side. On the other side of the hub part 8 there is a cover 23, which forms the other end stop and seals the interior of the hub part 8 to prevent the leakage of lubricant. The length adjustment mechanism 6 is shown in a central position with a path of displacement a to both sides.

From Fig. 2 it can be seen that the shaft 5 together with the second joint half 4 forms one unit and has two aligning journals 18. -These journals are connected to the annular intermediate element 3 via bearings 20. The intermediate element 3 is connected via two further aligning journals 19 via bearings 21 with the first joint half 2. As can be seen from Fig. 1, the bearings 21 can be disposed in a bearing block 22, which in turn is secured to the first joint half 2 in a known way. The axes of the journals 18 and 19 are at right angles to one another and preferably lie in a single plane.

Fig. 3 shows a section through the hub part 8 in the region of the rollers 9 and the joint bearings of the other universal joint 11. The second joint half 14 of this joint 11 is directly formed by the hub part 8, and, similar to the design of joint 1, has two journals 18. The kinematic coupling by means of the annular intermediate element 13 corresponds to that of joint 1 as shown in Fig. 2. By the radially outward arrangement of bearings 20 and 21, in the centre of the joint there is created enough space so that the hub part 8 can extend right into the plane of the journal axes or even further to the first joint half 12.

As a result there is a clear reduction in the total length.

The annular intermediate element 3, 13 can be oval, as is also seen in Fig. 2. As a result the external diameter of the first joint halves 2, 12 can be reduced so that the bearings 20, 21 are approximately the same distance from the axis of rotation. As is customary, the journals 18 on the hub part 8 are preferably disposed in the same plane as the journals 18 on the shaft part 5 so as to avoid errors in the angle of rotation. The bearings 20 and 21 can be lubricated via grease nipples 24.

The exemplified embodiment described shows a tripod length adjustment mechanism 6, in which the rollers 9 are secured via journals 10 to the stub shaft 7. With this shaft design it is also possible to secure the rollers to the hub part via journals and to perform the rotational drive via longitudinal grooves on the stub shaft.

Claims

1. A telescopic universal-joint shaft having a lengthadjustable shaft part (5) and also two universal joints (1, 11), which respectively consist of two joint halves (2, 4, 12, 14) connected via an intermediate element (3, 13), characterised by the combination of the following features: a) at least one of the intermediate elements (3, 13) on the universal joints (1, 11) is constructed as a circle, b) the length-adjustable shaft part (5) has a per se alone known tripod adjustment mechanism (6) with a central stub shaft (7) and a hub part (8) enclosing said stub shaft in a cylindrical shape, with the stub shaft (7) and the hub part (8) being in form-locking rotational connection via roller elements (9).

2. A universal joint shaft according to Claim 1, characterised in that the roller, elements (9) are securely supported on radially directed bolts (10) on the stub shaft (7) and are guided in paraxial grooves (15) on the hub part (8).

3. A universal joint shaft according to Claim 1 or 2, characterised in that the hub part (8) is guided and centred on the shaft part (5) so that it slides and fits tightly.

4. A universal joint shaft according to one of Claims 1 to 3, characterised in that the interior of the hub part (8) is sealed with respect to the outside and is filled with a lubricant.

5. A universal joint shaft according to one of Claims 1 to 4, characterised in that the annular intermediate element (3, 13) has two aligning journals (19) directed radially outwards and is connected to one of the joint halves (1, 2, 11, 12) via bearings (21).

6. A universal joint shaft according to one of Claims 1 to 4, characterised in that at least one of the annular intermediate elements (3, 13) has two mutually coaxial journals (19) extending radially outwards and - displaced from these by 900 - has two mutually coaxial bores for receiving two journal bearings (20) for journals (18) of the associated joint half (4, 14 or 8 respectively).

7. A universal joint shaft according to Claim 6, characterised in that the annular intermediate element (3, 13) has a substantially oval shape when seen in the axial direction.

8. A universal joint shaft according to one of Claims 1 to 7, characterised in that the shaft part (5) and/or the hub part (8) has aligning journals (18) directed radially outwards, which from the radially inward direction are connected to the annular intermediate element (3, 13) via bearings (18), with the axes of the journals 18 and 19 being at right angles to one another.

9. A universal joint shaft according to Claim 8, characterised in that the axes of the journals (18, 19) on the intermediate element (3, 13) lie in one plane.

10. A universal joint shaft according to Claim 8, characterised in that the grooves (15) in the hub part (8) extend axially at least into the region of the journals (18) directed radially outwards.

11. A universal joint shaft according to Claim 5, characterised in that the bearings (21) are enclosed by a bearing block (22), which is secured to the first joint half (2, 12).

12. A universal joint shaft constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as shown in the accompanying drawings.