FORM 2
THE PATENT ACT 1970 (39 of 1970)
&
The Patents Rules, 2 003 COMPLETE SPECIFICATION (See Section 10, and rule 13)
1. TITLE OF INVENTION BALL JOINT
2. APPLICANT(S)
a) Name : ZF FRIEDRICHSHAFEN AG b.) Nationality : GERMAN Company c) Address : 8803 8 FRIEDRICHSHAFEN
GERMANY
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to, be performed : -

The invention relates to a ball-and-socket joint according to the preamble of claim 1.
A ball-and-socket joint for a motor vehicle with a housing and a ball pivot supported rotatably and pivotably in the housing as well as with a sealing bellows is disclosed by DE195 45 567 Al. According to the disclosure content of this printed publication, the sealing bellows is mounted in a sealing manner with a first sealing bellows edge on the ball pivot and with a second sealing bellows edge on the housing, wherein the sealing bellows, executed as a whole in one piece, has at least two sections of different geometry between its sealing bellows edges, of which sections a first section forms a bellied contour and a second section has an extension along the outer surface and in the direction of the longitudinal axis of the housing.
With a ball-and-socket joint formed in such a way, it is possible compared with other designs to achieve a very large angular rotation of the ball pivot supported in the housing relative to the housing without in this case fearing damage to the sealing bellows sealing the internal joint components. This comparatively enlarged angular rotation is achieved in that the sealing bellows extends with its second section along the outer surface and lying close to the housing. If the ball pivot is pivoted in this case by means of the joint ball formed on it in the housing, the sealing bellows configured according to the printed publication is able to yield to this pivoting movement. On the side of the sealing bellows located in the pivot direction of the ball pivot, the second section of the sealing bellows is lifted from the housing, because an axial load is exerted on this second section and the sealing bellows has elastic properties. On the opposite side, the second section of the sealing bellows is loaded by a tensile stress. On account of the parts of this sealing bellows lying close to the housing, it is able to compensate for this tensile stress, however. In the ball-and-socket joint described in DE 195 45 567 Al, a lubricating grease is provided for lubricating the internal joint components. The sealing bellows serves in this case as a lubricant reservoir. According to experience, however, it tends on account of the lubricating grease present to adhere to the housing outer surface in the area of its

second section lying close to the housing. This circumstance is to be observed to a greater degree the older the lubricating grease present in the ball-and-socket joint. The function that is to be achieved by the second section and its lying close to the housing, namely the lifting and thus the relieving of the sealing bellows that is to be moved, is thus no longer fulfilled, however. The sealing bellows tends to wear prematurely, therefore, even in the case of such a design of a ball-and-socket joint. Due to the enlarged angular rotations realised by the ball-and-socket joint compared with known ball-and-socket joint designs, undue stress is namely placed on the sealing bellows. If it is then no longer capable of lifting off the housing, this leads in the fold sections forming to a tendency to crack, which ultimately leads to permanent damage to the sealing bellows.
The object of the invention is to provide a ball-and-socket joint for a motor vehicle, the sealing bellows of which joint reliably facilitates large angular rotations of the ball pivot over a long life cycle without thereby being subject to enhanced wear.
The invention achieves this object with the features of claim 1.
Further configurations of the invention are reproduced in the following sub-claims.
A ball-and-socket joint for a motor vehicle with a housing and a ball pivot supported rotatably and pivotably in the housing as well as with a sealing bellows, which lies in a sealing manner with a first sealing bellows edge on the ball pivot and with a second sealing bellows edge on the housing, wherein the one-piece sealing bellows has at least two sections of different geometry between its sealing bellows edges, of which sections a first section forms a bellied contour and a second section has an extension along the outer surface and in the direction of the longitudinal axis of the housing, was developed according to the invention so that the inner surface of the second section of the sealing bellows and/or the outer surface of the housing

corresponding hereto has a surface geometry with a varying direction of progression.
With the configuration of a ball-and-socket joint according to the invention it is possible to significantly reduce the contact surface between second section of the sealing bellows and housing surface overall. Due to the smaller contact surface, the sealing bellows no longer has a tendency in the second section to bind with the housing surface and adhere to this. This is also the case if a lubricating grease is used in the ball-and-socket joint and the sealing bellows is used in this case as a lubricating grease reservoir. Even stubborn lubricating grease materials that tend to resinify or should be subject to such a change on account of thermal or other influences can no longer cause an adhesive connection between sealing bellows and housing outer surface in a configuration of the ball-and-socket joint according to the invention. On the whole the service life of a ball-and-socket joint could thus be improved and premature wear of the sealing bellows avoided due to the invention. A ball-and-socket joint arranged in such a way is capable of implementing large angular rotations of the ball pivot relative to the housing without causing damage to the sealing bellows. In trials, angular rotations of the ball pivot of more than 50° relative to the housing could be achieved in long-term loading oi the ball-and-socket joint without damage to the sealing bellows occurring.
According to a first embodiment of the invention, the varying direction of progression can be a wave contour. This wave contour can be formed both on the inner surface of the second section of the sealing bellows and on the outer surface of the housing corresponding thereto. A wave contour is advantageous for the realisation of the inventive idea, because it facilitates an alternation of wave crests and wave troughs without sharp-edged transitions leading to damage to the sealing bellows. A sinusoidal wave contour is preferred, but this is not absolutely necessary for the realisation of the invention.

Apart from a wave-shaped contour, it is also possible to provide cam-like bumps on the inner surface of the sealing bellows in the area of its second section. These camlike bumps can run distributed over the entire inner surface of the second section of the sealing bellows or also be arranged collected in groups. Due to the cam-like bumps, punctiform contact is achieved between housing outer surface and inner surface of the sealing bellows. These contact points between the surfaces, which points are very small in cross-section, make lifting of the second section of the sealing bellows easier on pivoting of the ball pivot due to low friction between the surfaces.
In addition, however, it is also possible in reverse to provide cam-like bumps on the outer surface of the housing corresponding to the second section of the sealing bellows. Since the cost outlay for manufacturing a ball-and-socket joint according to the invention is influenced by the manufacturing technology outlay to produce the cam-like bumps or a wave contour, it can thus be decided whether the cam-like bumps are provided on the inner surface of the second section of the sealing bellows or on the outer surface of the housing.
A further variant of a ball-and-socket joint according to the invention consists further in the second section of the sealing bellows having linear bumps at least on sections on its inner surface. As already described earlier in connection with the cam-like bumps, the arrangement can be realised singly or collected in groups. A linear contact between the surfaces also leads to the effect that the sealing bellows no longer adheres to the housing surface,
By analogy with this, it is also possible that linear bumps are present at least on sections of the outer surface of the housing corresponding to the second section of the sealing bellows.

Sealing bellows for ball-and-sockets joints are usually given a bellied contour. To keep the geometrical dimensions of the sealing bellows as a whole within limits, it is proposed that the second section of the sealing bellows is attached directly to the first section of the sealing bellows. Elaborate transitions between the sections of the sealing bellows are thus avoided. The sealing bellows can be executed very compactly and according to the requirements placed on it. Furthermore, a material saving is thus achieved and the costs of manufacturing the ball-and-socket joint can be reduced.
To be able to achieve angular rotations of the ball pivot relative to the housing that are as large as possible, the aim of a further development of the invention is that the second section of the sealing bellows extends, viewed in the direction of the longitudinal axis of the housing, along a substantial part of the outer surface of the housing. Due to this relatively long extension of the second section of the sealing bellows on the outer surface of the housing, sufficient material is made available to be able to realise the large angular rotations mentioned at the beginning without damage to the sealing bellows arising.
A specific embodiment of this development of the invention can be seen in the fact that the second section of the sealing bellows extends, viewed in the direction of the longitudinal axis of the housing, over at least 2/3 of the housing along the outer surface of the housing. With an execution of this kind, the possibility is created of realising the aforementioned angular rotations.
The invention is explained in greater detail below with reference to the enclosed drawing. The practical example shown does not represent any restriction of the variant illustrated, but serves purely to explain the principle of the invention. To be able to demonstrate the mode of operation according to the invention, only one considerably simplified schematic diagram is show in the figure, in which components that are not essential to the invention have been omitted. This does not

mean, however, that such components are not present in a solution according to the invention.
Figure 1 shows a view in perspective of a ball-and-socket joint in partial section and
Figure 2 shows an illustration, enlarged in part, of the second section of the sealing bellows.
The ball-and-socket joint shown in figure 1 has a housing 1. Supported rotatably and pivotably in the housing 1 is a ball pivot 2. To improve the bearing properties, the ball-and-socket joint according to the illustration has a bearing shell 12, which takes up the joint ball of the ball pivot 2 with its inner circumferential surface and is inserted with its outer circumferential surface directly into the housing 1 of the ball-and-socket joint The ball-and-socket joint also has a sealing bellows 3, which lies with a first sealing bellows edge 4 in a sealing manner directly on the pin-shaped section of the ball pivot 2. On the side opposite this first sealing bellows edge 4, the sealing bellows 3 has a second sealing bellows edge 5, which is inserted into a corresponding groove-shaped recess in the housing 1, forming a seal, and is fixed on the housing 1 by a clamping ring, which is not described in further detail. The first sealing bellows edge 4 is likewise fixed on the ball pivot 2 by means of a clamping ring. The sealing bellows 3, which is executed as a whole in one piece, has two sections 6 and 7 that differ from one another in their geometry. In the lower area assigned to the pin-shaped part of the ball pivot 2, the sealing bellows has the first section 6, which here has a bellied contour. Directly adjacent thereto, the first section 6 of the sealing bellows 3 passes over into a second section 7, which extends along the outer surface of the housing 1 lying close to it. It is also evident from the illustration in figure 1 that the axial extension of the second section 7 of the sealing bellows 3 takes place over a substantial part of the housing 1. Where axial extension is referred to here, the direction of the components in the direction of the

longitudinal axis 9 of the housing 1 is always meant. In the representation in figure 1, this longitudinal axis 9 coincides with the longitudinal centre line of the non-deflected ball pivot 2. In the transitional area between the pin-shaped section and the joint ball of the ball pivot 2, this has a ball pivot neck 13, which is slightly reduced in cross-section relative to the pin-shaped section of the ball pivot 2 and here has a slightly conical progression.
The special feature according to the invention emerges more clearly from the enlarged detail illustration in figure 2. This detail illustration shows in part the area of the second section 7 of the sealing bellows 3 at the transition from the first section 6 of the sealing bellows 3. The sealing bellows 3 here has an inner surface 10, which is provided with a plurality of cam-like bumps 11. These cam-like bumps 11 come directly into contact with the outer surface 8 of the housing 1 with their highest elevation. Due to this contact pairing, the cam-like bumps 11 have a punctiform contact in each case with the outer surface 8 of the housing 1, so that only a very small surface is in direct contact. Adhesion of the second section 7 of the sealing bellows 3 is thus avoided, even if a lubricating grease is used in the sealing bellows 3 to lubricate the inner joint components. The large angular rotation of the ball pivot 2 achievable in this way inside the housing 1 is possible without the fear of damage to the sealing bellows 3 over the lifetime of the ball-and-socket joint.

Reference symbol list
1 Housing
2 Ball pivot
3 Sealing bellows
4 First sealing bellows edge
5 Second sealing bellows edge
6 First section of the sealing bellows
7 Second section of the sealing bellows
8 Outer surface of the housing
9 Longitudinal axis
10 Inner surface of the sealing bellows
11 Bumps
12 Bearing shell
13 Ball pivot neck

WE CLAIM:
1. Ball-and-socket joint for a motor vehicle with a housing (1) and a ball pivot (2) supported rotatably and pivotably in the housing (1) as well as a sealing bellows (3), which lies in a sealing manner with a first sealing bellows edge (4) against the ball pivot (2) and with a second sealing bellows edge (5) against the housing (1), wherein the one-piece sealing bellows (3) has at least two sections (6, 7) of different geometry between its sealing bellows edges (4,5), of which sections a first section (6) forms a bellied contour and a second section (7) has an extension along the outer surface (8) and in the direction of the longitudinal axis (9) of the housing (1), characterised in that the inner surface (10) of the second section (7) of the sealing bellows (3) and/or the outer surface (8) of the housing (1) corresponding hereto has a surface geometry with varying direction of progression.
2. Ball-and-socket joint according to claim 1, characterised in that the varying direction of progression forms a wave contour.
3. Ball-and-socket joint according to claim 1, characterised in that the second section (7) of the sealing bellows (3) has cam-like bumps (11) on its inner surface (10).
4. Ball-and-socket joint according to claim 1, characterised in that cam-like bumps (11) are present on the outer surface (8) of the housing (1) corresponding to the second section (7) of the sealing bellows (3).
5. Ball-and-socket joint according to claim 1, characterised in that the second section (7) of the sealing bellows (3) has linear bumps (11) at least on sections on its inner surface (10).

6. Ball-and-socket joint according to claim 1, characterised in that linear bumps (11) are present at least on sections on the outer surface (8) of the housing (1) corresponding to the second section (7) of the sealing bellows (3).
7. Ball-and-socket joint according to one of the preceding claims, characterised in that the second section (7) of the sealing bellows (3) is executed directly adjacent to the first section (6) of the sealing bellows (3).
8. Ball-and-socket joint according to one of the preceding claims, characterised in that the second section (7) of the sealing bellows (3) extends, viewed in the direction of the longitudinal axis (9) of the housing (1), along a substantial part of the outer surface (8) of the housing (1).
9. Ball-and-socket joint according to one of the preceding claims, characterised in that the second section (7) of the sealing bellows (3) extends, viewed in the direction of the longitudinal axis (9) of the housing (1), over two-thirds of the housing (1) along the outer surface (8) of the housing (1).