FORM 2
THE PATENT ACT 1970 (39 Of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION [See Section 10, and rule 13


TITLE OF INVENTION BALL JOINT

APPLICANT(S)
a) Name
b) Nationality
c) Address

ZF FRIEDRICHSHAFEN AG GERMAN Company 88038 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 joint for a motor vehicle, comprising a ball pin that is accommodated rotatably and pivotably in a single- or multi-part bearing shell, which is fixed by means of a cover ring in a housing. Between the cover ring and the housing there is situated in the assembled state of the ball joint a metal deformation element that performs a sealing function.
Such a ball joint is already known from EP 1 432 920 Bl. The ball joint disclosed in the said document has a deformation element, which is referred to in the document as a "compression element" and which may be disposed either on the cover ring or on a face of the housing that is suitable for this purpose. During assembly of this ball joint the deformation element is compressed, i.e. plastically deformed. In order to be able to achieve this plastic deformation, the choice of material for such constructions is very restricted because one of the corresponding components (cover ring or housing) has to be made of a relatively soft material and the other from a more rigid material. The correct choice of material pairing also has to be observed with regard to the development of electrochemical contact corrosion. Thus, for example frequent use is made of aluminium, which does admittedly offer considerable advantages also on account of its low weight. Aluminium however is a cost-intensive material. What is more, the manufacturing outlay of the known ball joints is relatively high because a considerable expenditure of force is needed to compress the deformation element. This in turn means that it takes additional time and energy to manufacture the ball joint.
The inventors have set themselves the object of further developing a known ball joint in such a way that the sealing of the inner joint components is improved on the whole, while at the same time providing an economical design.
This object of the invention is achieved by the features of claim 1. Special constructions of the invention are indicated in the appended sub-claims.

The inventors have recognized that for a ball joint of a motor vehicle, comprising a ball pin that is accommodated rotatably and pivotably in a single- or multi-part bearing shell, which is fixed by means of a cover ring in a housing, wherein disposed between cover ring and housing is a metal deformation element that in the assembled state of the ball joint performs a sealing function, it is particularly advantageous if during assembly of the ball joint the deformation element is elastically deformed and is disposed on the housing and/or on the cover ring.
By designing the deformation element as an elastic member an optimum sealing of the inner joint components of the ball joint may be achieved. As a result of the elastic properties of the deformation element tolerances caused by external influences, such as for example temperature within the sealing region may be compensated without difficulty. The renunciation of a plastic deformation of the deformation element in favour of an elastic deformation therefore represents a substantial improvement of the ball joint according to the present invention. What is more, there are now almost no restrictions on the choice of material for the cover ring and the housing. This has the advantage that both components may be manufactured for example from a high-strength material such as steel. This not only allows a reduction of the cost of manufacture. It also makes it possible for such a ball joint according to the invention to have smaller dimensions combined with increased mechanical strength properties.
According to a refinement of this inventive idea it is proposed that the deformation element is formed integrally on the housing and/or on the cover ring. By virtue of forming the deformation element integrally on the housing and/or on the cover ring, the deformation element may be produced without additional manufacturing outlay during manufacture of the respective component. In this way, it is possible also to realize any desired cross-sectional geometries.
According to a development of the invention the inventors further propose that the deformation element prior to its deformation has a saw-tooth-like cross-sectional
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contour. As the cover ring of the ball joint in the course of fitting is moved into the housing, wherein the deformation element is deformed, a saw-tooth-like cross-sectional contour of the deformation element is particularly suitable for promoting the elastic deformation.
For further improving a directed deformation of the deformation element it is further proposed that a contact face associated with the deformation element has a contour that during assembly of the ball joint promotes the directed deformation of the deformation element. Thus, the surfaces that correspond with one another are, on the one hand, the contact face and, on the other hand, the inclined surface of the saw-tooth-like cross-sectional contour of the deformation element. Thus, during the axial feed movement of the cover ring into the housing a purposeful and predefinable deformation of the deformation element may be realized as a result of the design of the faces that are in mutual contact.
The deformation element after its deformation accordingly preferably has an arc-shaped portion. The originally saw-tooth-like cross-sectional contour of the deformation element is therefore deformed elastically into an arc-shaped portion. This arc-shaped portion has turned out to be a particularly advantageous sealing face because, in addition to optimum elasticity, it also provides a sealing face of adequate width.
The arc-shaped portion of the deformation element together with the corresponding contact face forms a seal. In this case, a sealing face is formed, which is circumferential after the elastic deformation of the deformation element. Thus, by means of the deformation element according to the invention it is easily possible to realize a circumferential ring seal between the cover ring and the housing of the ball joint and thereby avoid the drawbacks of the prior art.
Further features and advantages of the invention arise from the sub-claims and the following description of a preferred embodiment with reference to the drawings.
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These show in particular:
Figure 1: a cross section through a ball joint having the features according to the invention;
Figure 2; the enlarged representation of the detail II from Figure 1 during assembly of the ball joint;
Figure 3: a detail enlargement of the sub-region II of a ball joint represented in Figure 2 for a fully assembled ball joint.
The embodiment of a ball joint according to the invention shown in Figure 1 presents in cross section a cutting course along the longitudinal centre line of the non-deflected ball pin 1. The ball pin 1 is mounted rotatably and pivotable inside the housing 3. To improve the bearing properties between the ball pin 1 and the housing 3 there is a bearing shell 4, which almost completely surrounds the joint ball 8 formed on the ball pin 1 and is inserted into the housing 3. A cover ring 2 is used to fix the bearing shell 4 inside the housing 3. The cover ring 2 has on its outer surface a saw-tooth-like structure, by means of which it may be fixed in an as such known manner in the housing 3. The cover ring 2 is used likewise to receive the edge region of a bellows-type seal 10. A clamping ring 11 is used to fix this edge region of the bellows-type seal 10. The other end of the bellows-type seal 10 is fixed by its edge region directly on the ball pin 1 of the ball joint. Here too, a clamping ring 12 is used to fix the bellows-type seal edge of the bellows-type seal 10. The bellows-type seal 10 therefore seals the housing opening 9 disposed at one end of the housing 3.
In order also to enable optimum sealing against the penetration of moisture and impurities into the interior of the ball joint in the region of the connection between housing 3 and cover ring 2, the solution according to the invention is described in detail below with reference to the enlarged detail II from Figure 1.
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Figure 2 shows, as an enlarged detail, the sub-region II from Figure 1. The ball pin 1 is accommodated by its joint ball 8 in the manner already described above rotatably and pivotably in a bearing shell 4. The bearing shell 4 is in turn inserted into the housing 3. To fix the bearing shell 4 inside the housing 3 the cover ring 2 is used. The cover ring 2 is moved into the housing 3 during assembly of the ball joint. In this case, the saw-tooth-like contour formed on the outer surface of the cover ring 2 engages progressively into the corresponding surface of the housing 3 that is provided for this purpose. Thus, a first fixing of the position of the cover ring 2 inside the housing 3 may be achieved. The cover ring 2 is initially moved far enough into the housing 3 for the deformation element 5, which is disposed on the cover ring 2, to come into abutment with the contact face 6 of the housing 3 that lies opposite it. In a subsequent step, through the application of an increased inward-pressing force the deformation element 5, which up to this point still had a saw-tooth-like cross section, is elastically deformed. In this case, the shaping of the contact face 6 promotes a directed movement of the deformation of the deformation element 5. A sealing face is formed between the cover ring 2 and the housing 3. The housing opening edge portion 15 surrounding the housing opening 9 is then deformed in the direction of the joint ball 8 of the ball pin 1 in such a way that it comes into abutment with the flange 14 formed on the cover ring 2. Thus, the cover ring 2 is finally fixed in position. Any impurities or liquids penetrating in the region between flange 14 and housing opening edge region 15 are reliably retained by the deformed deformation element 5, which now forms a sealing face. In interaction with the bellows-type seal 10, which is inserted into the groove 13 of the cover ring 2, an optimized sealing of the ball joint according to the invention arises as a whole.
Figure 3 shows, once again as an enlarged detail, a sectional representation that shows the state of the ball joint after completion thereof. Here, in particular the arc-shaped portion 7 of the deformation element 5 is important because it forms the previously already described sealing face with the corresponding contact face 6 of the housing 3. Also evident from Figure 3 is the deformed housing opening edge region 15 that immediately abuts the flange 14 of the cover ring 2.
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It is also self-evident that the previously described features of the invention are usable not only in the combination indicated in each case but also in other combinations or individually without departing from the scope of the invention. It is likewise within the scope of the invention to effect a mechanical reversal of the functions of the individual mechanical elements of the invention.
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List of reference characters

1 ball pin
2 cover ring
3 housing
4 bearing shell
5 deformation element
6 contact face
7 arc-shaped portion
8 joint ball
9 housing opening
10 bellows-type seal
11 clamping ring
12 clamping ring
13 groove
14 flange
15 housing opening edge region

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WE CLAIM:
1. Ball joint for a motor vehicle, comprising a ball pin (1) that is accommodated
rotatably and pivotably in a single- or multi-part bearing shell (4), which is
fixed by means of a cover ring (2) in a housing (3), wherein disposed between
cover ring (2) and housing (3) is a metal deformation element (5) that in the
assembled state of the ball joint performs a sealing function,
characterized in that
the deformation element (5), which is elastically deformed during assembly of the ball joint, is disposed on the housing (3) and/or on the cover ring (2).
2. Ball joint according to claim 1,
characterized in that
the deformation element (5) is formed integrally on the housing (3) and/ or on the cover ring (2).
3. Ball joint according to one of claims 1 to 2,
characterized in that
the deformation element (5) prior to its deformation has a saw-tooth-like cross-sectional contour.
4. Ball joint according to one of claims 1 to 3,
characterized in that
a contact face (6) associated with the deformation element (5) has a contour that during assembly of the ball joint promotes the directed deformation of the deformation element (5).
5. Ball joint according to one of claims 1 to 4,
characterized in that
the deformation element (5) after its deformation has an arc-shaped portion
(7)-
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6. Ball joint according to claim 4 and 5,
characterized in that
the arc-shaped portion (7) of the deformation element (5) together with the contact face (6) forms a seal.
7. Ball joint according to one of claims 1 to 6,
characterized in that
the deformation element (5) after its deformation has a circumferential sealing
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face.