FORM 2
THE PATENT ACT 1970 (39 of 1970)
&
The Patents Rules, 2003 COMPLETE SPECIFICATION
(See Section 10, and rule 13]
1. TITLE OF INVENTION
JOINT ARRANGEMENT AND/OR BEARING ARRANGEMENT

2. 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 : -

Description
The invention relates to a joint- and/or bearing arrangement according to the preamble of claim 1 as well as to a motor vehicle having one or more of such joint-and/or bearing arrangements, in particular in chassis- and/or steering parts.
EP 0 505 719 Bl discloses a joint arrangement comprising a joint body, which in sections is spherical and in the fitted state is movable in a joint socket. This is prevented from being pulled out by means of thrust collars at its axially outer ends. Such joint arrangements may be used for high specifications with radial external tolerances of a few hundredths of a millimetre and may be press-fitted with high axial forces of typically ten to fifteen KN into an outer sleeve body, for example an end region of a steering knuckle or MacPherson strut unit. Even an equally precise manufacture of the sleeve body may still lead to an overlap with a radially inwardly acting force, which because of the direct abutment of the joint socket with the inner wall of the joint housing is transmitted from this joint housing directly to the joint socket. Particularly when for this joint socket a comparatively hard and brittle high-performance plastics material is used, for example a PEEK plastics material, which meets high pressure/heat requirements and is therefore often to be preferred to a POM plastics material that tends to flow above ca. 80°C, this leads to an adverse influencing of the joint properties as a result of e.g. greater force of pressure upon the joint body, this varying the torque for movement of the joint body and hence the driving comfort in a vehicle, or even to fractures or cracks in the joint socket.
The underlying problem of the invention is to avoid damage or operating restrictions owing to the action of a radial inward force during the press-fitting operation.
The invention solves this problem by means of a joint arrangement having the features of claim 1 as well as by a motor vehicle having the features of claim 15.
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With regard to advantageous refinements! and developments of the invention, reference is made to the further claims 2 to 14.
By means of a force-equalizing element according to the invention a loading of the joint socket by radial force during the press-fitting operation is at least almost entirely avoided. Owing to deformation of at least a sub-region of the force-equalizing element the radial force is kept away from the joint socket, thereby allowing the joint socket to remain uninfluenced even when it itself is of a very brittle and thin-walled design.
When the force-equalizing element is effective uniquely during the operation of press-fitting the joint- and/or bearing arrangement into a sleeve body, this prevents the occurrence during routine operation of excessively high excursion tolerances even without external force loading in the joint arrangement. The tolerance compensation effective only during the press-fitting operation may be realized in particular by a plastic deformability upon the introduction of radial force.
In this case, the inner wall of the housing may participate in the deformation in that the deformable region upon loading of the housing with a radially inwardly directed force presses into the inner wall of the housing. The deformable region may then itself have a high strength that is in particular at least as great as that of the joint socket in order to prevent a new weak point being formed by the force-equalizing element.
In this case, in a particularly advantageous manner the deformable region may take the form of at least one outwardly protruding annular or annular segment projection, so that this projection serves as a support on the inner wall and the rest of the force-equalizing element at least in the unloaded state does not rest with its full surface on the inner wall but may pivot slightly about this support during the press-fitting operation.
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The force-equalizing element is disposed between joint housing and joint socket and may be in large-area contact both with an inner wall of the joint housing and with an outer wall of the joint socket and therefore keep radially inwardly acting force away from the joint socket. In particular, the force-equalizing element may surround the joint socket like a sleeve over almost the entire length of the joint arrangement, so that at no point is the joint socket in direct contact with the inner wall of the joint housing. The outside of the joint housing - as well as the inside of the sleeve body provided for receiving the fully assembled joint arrangement - may be designed with parallel walls without conicality.
Alternatively, for example two force-equalizing elements may be provided axially spaced apart from one another, wherein, in this case also, in the intermediate region the joint socket is required to have no contact with the joint housing in order to prevent a transmission of radial force from the housing to the joint socket. Should there be contact of the joint socket with the inner wall of the housing in the clearance space, the joint socket may be of an elastically resilient design there and for example at the side facing the joint body have an annular channel as a lubricant reservoir, which simultaneously provides a radially inwardly directed deformation path.
In addition to the plastic deformation, an elastic deformation of the force-equalizing element is possible, which also allows a spring force in the force-equalizing element.
A joint arrangement according to the invention is capable of being subject both to torsional stress about the pin axis in the manner of a bearing and to bending stress and is therefore usable in many ways, for example inside chassis- and/or steering parts of motor vehicles, for example to connect MacPherson strut units or to support wheels by means of more or less transversely disposed control arms in multiple control arm shafts.
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Further advantages and features of the invention arise from embodiments of the subject matter of the invention that are illustrated in the drawings and described below.
The drawings show:
Fig. 1 a longitudinal sectional view of a first construction of a joint according to
the invention having two force-equalizing elements axially spaced apart from one another and rounded in the direction of the joint socket,
Fig. 2 a view similar to Fig. 1 having two force-equalizing elements extending
rectilinearly obliquely in the direction of the joint socket,
Fig. 3 a view similar to Fig. 2 having two force-equalizing elements configured
as polygons relative to the joint socket,
Fig. 4 a view similar to Fig. 3 having two force-equalizing elements separated
in a spring-like manner and by terminating rings,
Fig. 5 the detail V in Fig. 3,
Fig. 6 the detail VI in Fig. 5,
Fig. 7 a view similar to Fig. 6 with complete course of a force-equalizing
element,
Fig. 8 a view similar to Fig. 7 of a construction having an intermediate layer,
Fig. 9 a view similar to Fig. 8 of a construction having three protruding annular
mouldings on the force-equalizing element,
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Fig. 10 a view similar to Fig. 8 of a construction having a wave profile on the force-equalizing element.
The joint arrangement 1 illustrated in Figure 1 comprises an axially extended joint body 2 having a protuberance 3 that is substantially spherical in the axially central region. This protuberance is held movably in a - frequently slotted - joint socket 4, wherein the radial outer surface 5 of the joint socket 4 according to Fig. 1 in section forms a curvature that extends three-dimensionally around the axis 6. The inner surface 7 of the joint socket 4 is in this example approximated in section by a polygon, wherein at the kink points lubricant reservoirs 8 extending round in an annular manner arise, this not being mandatory. To save costs and weight, the joint socket 4 may be made entirely of plastics material, wherein increasingly in order to meet high pressure/temperature requirements relatively hard and brittle PEEK plastics materials are used instead of POM plastics materials, which are softer but tend to flow at high temperatures.
The space between the joint body 2 and the joint socket 4 is filled here at least partially with a lubricant that is used to reduce the friction between the contact surfaces. The lubrication may in particular be provided for the whole planned service life of the joint 1.
The movement of the joint body 2 may be both an excursion in the direction of the arrows a, b and a rotation about the axis 6 of the pin 2. Thus, such a joint arrangement 1 may act also like a bearing and is referred to here also generally as a joint- and/or bearing arrangement.
The joint socket 4 is surrounded radially further out by a sleeve-shaped joint housing 9, the axial ends 10 of which after assembly of the joint 1 may be closed for example by means of a roll forming operation. Such a joint 1 may therefore as a whole be described also as a sleeve joint and, in a step following its assembly, may be pressed with an interference fit with an axial pressing force of typically several to several
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tens KN axially into a surrounding sleeve body - not illustrated here - e.g. into a through-bore formed by an end region of a steering knuckle or MacPherson strut unit receiver. The sleeve joint 1 may be manufactured with diameter tolerances in the region of several hundredths of a millimetre, as may the internal dimension of the receiving sleeve body.
According to the invention, there is disposed radially between the surrounding joint housing 9 and the joint socket 4 at least one force-equalizing element against radial loading, according to Fig. 1 two axially mutually spaced-apart force-equalizing elements 11, 12. These are in contact both with the radially inner wall of the joint housing 9 and with the outer wall of the joint socket 4. The force-equalizing elements 11, 12 are effective in the event of an overlap between the surrounding sleeve body and the joint 1 to be press-fitted and in this case ensure that a radially inwardly acting force is kept away from the joint socket 4. Alternatively, it would also be possible for an axially continuous force-equalizing element to surround the joint socket 4 like a sleeve over the entire length thereof.
The region 13, 14 to be deformed of the fundamentally identical-type force-equalizing elements 211, 212 according to Fig. 3 are illustrated in detail in Figures 5 and 6: in the event of a force acting radially in the direction of the arrow c, depending on the material selection and material pairing two effects may occur to differing degrees of intensity: on the one hand the annular region 14, which in section projects in a lug-like manner, plastically or elastically deforms, on the other hand this region 14 may dig into the inner wall of the surrounding joint housing 9, with the result that the joint housing 9 participates in the deformation. In either case, external force is kept, without any significant change of excursion, away from the joint socket 4 situated further in. The joint socket 4 therefore, given a sufficiently accurate fit of joint 1 and sleeve body, remains free of deformation. The torque therefore remains at least almost independent of the press-fit overlap. The comfort and the response characteristic of for example an axle equipped with joints according to the invention are therefore increased. It therefore becomes possible to
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construct plastic joint sockets 4 with very thin walls (of for example 0.8 millimetres) and hence save material, this on the one hand saving material costs but on the other hand also leading to a reduced material elasticity and hence a steeper force-excursion curve of the joint 1. Consequently, the result in the event of a low or even no introduction of force is also no mobility of parts 4, 2 of the joint 1 in the direction of the arrows a or b. The joint 1 does not shake and may retain its parameters very precisely even throughout continuous operation. In addition, as a side effect, because of the digging-in the ball tear-out force is increased and a further sealing against the penetration of water or oil is moreover effected. Equally, the force-equalizing elements 11, 12 outside of the regions 13, 14 may remain free of deformation, wherein the gap 15 between the elements 11,12 and the joint housing 9 may reduce as a result of the radial force. The regions 13,14 then serve as a support, about which in the event of introduction of a radial force the elements 11, 12 may pivot slightly inwards and act in a similar manner to a spring.
Thus, even after radial loading in the event of a press-fit overlap it is ensured that the joint 1 retains its exact tolerances of the joint socket 4 and without introduction of an external force no change of excursion of parts occurs in the joint 1. In the case of a plastic deformation of the regions 13, 14, this is guaranteed particularly when the force-equalizing elements 11,12 have at least the strength of the joint socket 4 and so even outside of the deformable regions 11, 12 offer a stable support of the joint socket 4 that is not influenced by the press-fit force.
As is evident from Fig. 1, the force-equalizing elements 11, 12 may be formed integrally with terminating rings, which effect in each case an axial securing and which engage into grooves 16 of the joint housing 9 and are secured against being pulled out axially by virtue of the roll-forming of the edge regions 10. This integral design reduces the number of parts to be used.
In the joint 101 according to a second embodiment (Fig. 2) the bearing shell 104 has a rectilinearly extending outer surface but its inner surface 7 is the same as in Fig. 1.
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The force-equalizing elements 111, 112 too are merely adapted to the altered external contour of the joint socket 4, without any alteration in their function.
The same applies to a joint 201 according to a third embodiment according to Fig. 3: here, the outer surface 205 of the joint socket 204 is, like the inner surface 7, of a polygon-like design. The force-equalizing elements 211, 212 are adapted thereto.
The joint 301 according to the further embodiment according to Fig. 4, on the other hand, shows as force-equalizing elements 311, 312 two spring washers, which as a whole are elastically deformable and do not require separate deformable regions 13, 14. Here, the force-equalizing elements are designed separately from the axial terminating rings 317, 318. However, in this case too, they might alternatively be of an integral design. The deformation of the force-equalizing elements 311, 312 here is effected elastically and may therefore be effective also during routine operation.
Otherwise, it is advantageous when the force-equalizing elements 11, 12, 111, 112, 211, 212 take up radial force only during the press-fitting operation and during subsequent operation execute no radial excursions that would flatten the force-excursion curve of the joint.
According to a further construction according to Fig. 8, the force-equalizing element 412 is provided with an elastically deformable intermediate layer relative to the wall of the joint housing 9. Such an intermediate layer ensures that even without the introduction of an external force an excursion of the parts 2, 204 in the direction of the arrows a, b is possible and to said extent makes the force-excursion curve very flat. On the other hand, the curve even throughout high loading remains almost constant, so that the quality of the joint in this case does not alter.
In the last two embodiments according to Figures 9 and 10, the deformable regions again take the form of protuberances of the force-equalizing elements 512, 612, here
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namely three saw-tooth-like annular protuberances 514 and three annular wave crests 614 respectively. These need not moreover be the same height in each case.
In each case, either, as illustrated here, the joint socket 4,104, 204, 304 over its entire axial shape has either no contact with the inner wall of the surrounding joint housing 9 or at a possible contact surface - not illustrated - may yield radially inwards e.g. by virtue of a bead at the opposite side facing the joint body 2. A radial inward force upon the joint housing 9 therefore never restricts the function of the joint socket 4, 104, 204, 304. The joint socket is not reduced in width and therefore does not exert an increased pressure on the joint body 2.
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List of reference characters

1 joint arrangement/joint/sleeve joint
2 joint body
3 protuberance
4 joint socket
5 outer surface
6 axis
7 inner surface
8 lubricant reservoirs
9 joint housing
10 axial ends/edge regions
11,12 force-equalizing elements
13,14 region
15 gap
101 joint
104 bearing shell
111, 112 force-equalizing elements
201 joint
204 joint socket
205 outer surface
211, 212 force-equalizing elements
301 joint
304 joint socket
311, 312 force-equalizing elements
317,318 terminating rings
412 force-equalizing element
512, 612 force-equalizing elements
514 annular protuberances
614 wave crests
A direction arrow
B direction arrow
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WE CLAIM:
1. Joint- and/or bearing arrangement (1; 101; 201; 301) for press-fitting into a surrounding sleeve body, in particular into an end region of a steering knuckle or MacPherson strut unit, wherein the joint- and/or bearing arrangement (1; 101; 201; 301) comprises a joint body (2), which is movable relative to a joint socket (4; 104; 204; 304), and a joint housing holding the joint socket (4; 104; 204; 304), characterized by at least one force-equalizing element (11,12; 111,112; 211,212; 311,312; 412; 512; 612), by means of which a force acting with a radial component upon the joint housing (9) during the press-fitting operation is kept away from the joint socket (4; 104; 204; 304) by deformation of at least one sub-region (13,14; 412a; 514; 614).
2. Joint- and/or bearing arrangement according to claim 1, characterized in that the force-equalizing element (11,12; 111,112; 211,212; 311,312; 412; 512; 612) is effective uniquely during the operation of press-fitting the joint- and/or bearing arrangement into a sleeve body.
3. Joint- and/or bearing arrangement according to one of claims 1 or 2, characterized in that the force-equalizing element (11,12; 111,112; 211,212; 311,312; 412; 512; 612) is in contact both with an inner wall of the joint housing (9) and with an outer wall of the joint socket (4; 104; 204; 304).
4. Joint- and/or bearing arrangement according to one of claims 1 to 3, characterized in that the region (13,14; 514; 614) that is deformable upon introduction of a radial force is plastically deformable.
5. Joint- and/or bearing arrangement according to one of claims 1 to 4, characterized in that the deformable region (13,14; 514; 614) upon introduction of a radial force presses into the inner wall of the joint housing (9).
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6. Joint- and/or bearing arrangement according to one of claims 4 or 5, characterized in that the deformable region (13,14; 514; 614) takes the form of an outwardly protruding annular or annular-segment projection.
7. Joint- and/or bearing arrangement according to one of claims 1 to 3, characterized in that the deformable region (311,312; 412a) is elastically deformable.
8. Joint- and/or bearing arrangement according to claim 7, characterized in that the deformable region (311,312; 412a) counters its deformation with a spring force.
9. Joint- and/or bearing arrangement according to one of claims 1 to 8, characterized in that the force-equalizing element surrounds the joint socket (4; 104; 204; 304) like a sleeve over almost the entire length thereof.
10. Joint- and/or bearing arrangement according to claims 1 to 8, characterized in that two force-equalizing elements (11,12; 111,112; 211,212; 311,312; 412; 512; 612) are provided, which are disposed spaced axially apart from one another between joint socket (4; 104; 204; 304) and joint housing (9).
11. Joint- and/or bearing arrangement according to claim 10, characterized in that the force-equalizing element (11,12; 111,112; 211,212; 311,312; 512; 612) is made of at least as strong a material as the joint socket (4; 104; 204; 304).
12. Joint- and/or bearing arrangement according to one of claims 1 to 11, characterized in that it is capable of being subject both to torsional stress about the longitudinal axis (6) of the joint body (2) and to bending stress.
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13. Joint- and/or bearing arrangement according to one of claims 1 to 12, characterized in that inner wall and outer wall of the joint socket (4; 104; 304) at least in sections do not run parallel to one another and on the inner wall lubricant reservoirs (8) are formed opposite the joint body (2).
14. Joint- and/or bearing arrangement according to one of claims 1 to 13, characterized in that the axial force for press-fitting the fully assembled joint-and/or bearing arrangement (1; 101; 201; 301) into a sleeve body is above eight KN.
15. Motor vehicle having at least one joint- and/or bearing arrangement (1) according to one of claims 1 to 14, in particular inside chassis- and/or steering parts.
Dated this 30th day of April, 2007
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ABSTRACT
In a joint- and/or bearing arrangement (1; 101; 201; 301) for press-fitting into a surrounding sleeve body, in particular into an end region of a steering knuckle or MacPherson strut unit, wherein the joint- and/or bearing arrangement (1; 101; 201; 301) comprises a joint body (2), which is movable relative to a joint socket (4; 104; 204; 304), and a joint housing holding the joint socket (4; 104; 204; 304), at least one force-equalizing element (11,12; 111,112; 211,212; 311,312; 412; 512; 612) is provided, by means of which a force acting with a radial component upon the joint housing (9) during the press-fitting operation is kept away from the joint socket (4; 104; 204; 304) by deformation of at least one sub-region (13,14; 412a; 514; 614).
To,
The Controller of Patents,
The Patent Office,
Mumbai
15
Figure 1