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

TITLE OF INVENTION
MOUNTING METHOD FOR AN ARTICULATION
SYSTEM FOR MOTOR A VEHICLE AXLE

SYSTEM AND ARTICULATION

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -
ZF FRIEDRICHSHAFEN AG GERMAN Company 88038 FRIEDRICHSHAFEN GERMANY

Declaration

Client Reference:
Title:
Parallel Reference:
Source Language:
Target Language:

EPT/57122GEN1
PCT/DE2006/002094
2804119
German
English

I, the undersigned, translator to Parallel Translations Limited of 15 Freemantle Business Centre, 152 Millbrook Road East, Southampton SO 15 1JR, hereby declare that I am conversant with the source and target languages and certify that, to the best of my knowledge and belief, the following is a true translation of the accompanying source document.



Description
The invention relates to a method of assembling a joint arrangement for a wheel control, in particular for a steerable, for example driven, axle of a motor vehicle, of the type defined in claim 1, and a joint arrangement of the type outlined in the introductory part of claim 10.
Joint arrangements of the above-mentioned type are used in so-called split wheel supports of McPherson axles, spring strut axles or wishbone axles, for example, although by no means exclusively. Such split wheel supports are distinctive due to the fact that a part of the wheel support that is sprung but can not effect a steering movement is provided with a pivotable insert, in particular a steering stub axle, which is specifically responsible for the actual steering movement of the wheel.
The particular advantage of such split wheel supports is that the essentially vertical steering axis about which the wheel is pivoted during the steering movement can be disposed at a smaller spread angle and closer to the mid-plane of the wheel without causing an undesirably high and/or positive steering roll radius at the same time as a result. This reduces disruptive knock-on effects of the driving and braking torque in particular, as well as the influence which uneven roads, wheel imbalances or transverse forces have on the steering of the vehicle. It also offers a way of better optimising the entire axle geometry, in particular the interaction of inclination, steering roll radius, track width and camber as well as tracking, thereby ensuring optimum vehicle control and a sensitive steering ability free of reaction forces under all driving conditions and within as large as possible a steering angle range.
A two-part, split wheel support of this type is known from publication DE 603 00 085 T2, for example. This known wheel support comprises a ball and socket joint and a roller bearing, and the interaction of these two joints determines the steering axis or pivot axis of the steerable steering stub axle relative to the stationary part of the wheel support. According to the teaching of this publication, the steering stub axle can therefore be pivoted about the steering axis defined by the two joints relative to a fork-type joint arrangement of the wheel support, which is sprung but stationary with respect to steering movements, as a result of which the steering movement is imparted to the corresponding wheel of the vehicle.
The wheel control joint formed by the two joints must therefore be designed as a fixed bearing/ loose bearing combination in order to be able to absorb unavoidable manufacturing and assembly tolerances and deformations of the joint and axle components which occur during operation. This is all the more important given that wheel supports or wheel control joints of this type have to be provided with an end-to-end orifice, especially in the case of driven axles, to provide the passage needed for the drive shaft of the wheel. The open and fork-shaped design of such a wheel support results in additional elasticity, however, causing the universal joint fork, the steering stub axle and the respective bearing support to deform as soon as the wheel control joint is subjected to reaction forces such as the effect of the road surface as well as driving, braking and centrifugal forces.
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Consequently, such reaction forces also unavoidably lead to certain static and/or dynamic misalignments and axial shifts between the pivotable steering stub axle and the stationary wheel support in the region of the two bearings.
To absorb such misalignments or axial shifts on the bearing side, a fixed bearing/oose bearing combination is generally used in wheel control joints known from the prior art and a rotatable and pivotable ball and socket joint is used as the fixed bearing. The loose bearing used for simultaneously absorbing any misalignments and axial shifts between the pivotable steering stub axle and stationary wheel support in the prior art is either a slide bearing with two different bearing surface areas for rotation/pivoting and axial displacement capacity, or a roller bearing with an additional axial and additional pivot angle degree of freedom is used, for example a toroidal roller bearing.
Known wheel control joints of this type with a fixed bearing and loose bearing are complex to produce and in particular assemble, however. This is primarily attributable to the fact that the stationary wheel support known from the prior art, which is usually designed as a universal joint fork, must be of a two part design so that the two bearing points, i.e. the fixed bearing and the loose bearing, can actually be fitted between the wheel support and steering stub axle, and the pivotable steering stub axle fitted through the opening of the two-part universal joint fork. In other words, at least one of the fork ends of the stationary wheel support or its universal joint fork must be designed as a separate component which can be connected to the wheel support or universal joint fork in order to accommodate one of the two pivot bearings, as may be seen in particular from Figures 2 and 4 of said publication DE 603 00 085 T2.
In the prior art, the steering stub axle and universal joint fork are therefore assembled by firstly connecting the pivotable steering stub axle and the stationary universal joint fork to one another by means of the top fixed bearing, provided in the form of a ball and socket joint. The bottom loose bearing is then fitted on the pivotable steering stub axle. Finally, having pivoted the steering stub axle into the two-part, stationary wheel support, the universal joint fork formed by it is closed, thereby resulting in the intrinsically pivotable unit comprising pivotable steering stub axle and stationary wheel support or universal joint fork.
In the first place, however, this necessarily two-part design known from the prior art is already complex in terms of its construction and thus tends to be cost-intensive. In addition, the two-part design of the wheel support increases the number of components and hence the complexity involved in assembling the wheel support, steering stub axle and pivot bearing. As a result, the non-sprung masses of the wheel suspension which make a decisive contribution to the driving properties and cushioning comfort are also undesirably increased.
Another decisive disadvantage of the split or two-part wheel support known from the prior art, however, resides In the fact that due to the large number of components associated with the universal joint fork of a two-part design, problems can arise in
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keeping to the intended narrow tolerances in the region of the pivot bearing between the stationary wheel support and pivotable steering stub axle.
For the loose bearing to be able to absorb misalignments and/or axial shifts which can occur during operation, as described above, the centre position of the bearing elements of the loose bearing in which the force-free state will be assumed must be very accurately observed when assembling the wheel support. However, due to the large number of individual components needed for universal joint forks known from the prior art - especially due to the two-part design - there is an unfavourable string of interlinked tolerances in this respect, which is why the centre position of the loose bearing of joint arrangements known from the prior art can often be set to only an inadequate degree of accuracy, which means that it can be only inadequately reproduced on a mass production scale.
If the tolerance position of the individual components is not as good as it should be, situations may even arise in which the axially displaceable loose bearing is already disposed at the limit of its permissible operating range in terms of axial displacements after assembly. The expansions of the universal joint fork and/or steering stub axle which then occur, particularly in driving mode, due to the effects of the driving dynamics or also due to the effects of temperature, can then no longer be absorbed by the pivot bearing of the steering stub axle in the form of pivoting movements and/or axial displacements of the loose bearing. This can lead to uncontrolled tensions between the steering stub axle and wheel support or universal joint fork, however, which can then lead to premature failure of the two pivot bearing points of the steering stub axle due to excessive strain on the bearing.
Against this background, the objective of this invention is to propose a joint arrangement for a wheel control and a method of assembling such a joint arrangement, whereby said disadvantages can be overcome. In particular, the method and the joint arrangement should guarantee an exact centre position of the loose bearing with reliable operation and processes and should do so on a reproducible basis. The joint arrangement should also be designed to have as low a mass as possible, be compact and have a long service life whilst also permitting cost-effective and faster production and assembly.
This objective is achieved on the basis of a method of assembling a joint arrangement incorporating the characterising features of claim 1 and by a joint arrangement as defined in claim 10.
Preferred embodiments are defined in the dependent claims.
The method proposed by the invention relates to the assembly of a joint arrangement for a wheel control, in particular for a driven axle of a motor vehicle, for example. Accordingly, the joint arrangement comprises a universal joint fork which can be fitted on a vehicle axle or on a transverse control arm or connected to an axle steering system - also referred to as a static wheel support - and a steering stub axle supporting the actual wheel bearing and assuming the steering function. The static
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