Title of Invention

CENTRAL COUPLING FOR A WISHBONE OF VEHICLES

Abstract Central coupling 1 for a wishbone of vehicles, in particular commercial vehicles, with a ball pivot 6 accommodated in a coupling housing 3, wherein the coupling housing 3 is formed from a coupling housing body 4 and a coupling housing floor 5, and the ball pivot 6 is formed from a turret-shaped ball pivot body 8 and a coupling ball 7 mounted on the ball pivot body 8, and the ball pivot 6 is swivellably and rotatably mounted in a bearing shell 24 secured in the coupling housing 3. The invention is characterised in that the coupling housing 3 is formed in one piece from the coupling housing body 4 and the coupling housing floor 5.
Full Text 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
CENTRAL JOINT FOR AN A-ARM OF MOTOR VEHICLES

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

ZF FRIEDRICHSHAFEN AG GERMAN Company 88038 FRIEDRICHSHAFEN GERMANY

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

The present invention relates to a wishbone bearing for guiding rear axles, in particular of commercial vehicles, and preferably relates to the central bearing of the wishbone on the rear axle.
Such wishbones are used in particular to guide rear axles of commercial vehicles, wherein two struts are connected at one end in an articulated manner to the structure of the vehicle and are connected at their other end, by means of a central coupling, in an articulated manner to the rear axle of the vehicle. At the same time the two struts are connected via a common coupling housing, in which is swivellably accommodated a coupling ball that is fixedly connected via a ball pivot to the axle.
Such an arrangement is shown for example in DE 2350087 Al, in which a bearing for the swivellable mounting is arranged between the coupling housing and coupling ball. The ball pivot consists in this connection of a coupling ball with a conical recess that co-operates with a similarly conical surface of a ball pivot body. The coupling ball and ball pivot body are joined by means of a bolt connection, the bolt being guided through an offset through hole of the coupling ball and engaging in a thread arranged in the ball pivot body. Because the bolt connection is from the coupling ball side, it is necessary to arrange a cover in the coupling housing in order to provide access to the bolt connection. The floor of the coupling housing is thus formed by a separate structural part. This has the disadvantage that additional structural parts, such as, for example, additional sealing and connection elements are necessary, which complicate the installation and increase the costs, and moreover form a possible leakage site of the central coupling.
The object of the invention is accordingly to develop and improve a central coupling for a wishbone, so that the construction and thus the installation is simplified and in addition an improved sealing function of the central coupling is provided.
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This object is achieved by a central coupling for a wishbone of vehicles having the feature of the main claim. Advantageous modifications and developments are given in the sub-claims.
For a central coupling for a wishbone of vehicles, in particular commercial vehicles, with a ball pivot swivellably and rotationally mounted in a coupling housing, wherein the coupling housing is formed from a coupling housing body and a coupling housing floor and the ball pivot is formed from a turret-shaped ball pivot body and a coupling ball mounted on the ball pivot body, as well as from a bearing shell fixed in the bearing housing, it is proposed according to the invention to form the coupling housing body and the coupling housing floor in one piece. In this way separate structural parts as well as separation joints in the region of the coupling housing are avoided, so that the installation can be considerably simplified compared to the prior art and in addition a sealed coupling
housing can be ensured on account of the absence of sealing joints. Particularly in the case of commercial vehicles, the region where the wishbone joins onto the shaft is seriously affected by dirt and moisture, so that the sealing function is even more important.
In an advantageous modification the coupling ball and the ball pivot body are connected to one another by means of a bolt connection, in which the ball pivot body is cylindrically shaped at its end facing towards the coupling ball and this end is inserted into a similarly cylindrical recess in the coupling ball. The diameter of the cylindrical end of the ball pivot body is at the same time larger than the internal diameter of the cylindrical recess of the coupling ball, so that between the coupling ball and the ball pivot body a uniform surface compression is exerted over the region of the common bearing surface, with a lower degree of distortion of the press-fit assembly and without any significant stress peaks, whereby the allowable operating loads can be considerably increased compared for example to a ball press-fit assembly. There is thus also no notch action, which could have the effect of reducing the service life of the turret-shaped ball pivot. Furthermore, due to the uniform
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surface compression the coupling ball is also uniformly expanded in the radial direction, so that no non-uniformed distortions can arise in the sliding pair consisting of the bearing shell and coupling ball. Instead, the bearing shell is uniformly prestressed.
By means of the bolt connection the coupling ball engages against a stop means, the stop means being formed by a, for example, face-turned surface of the cylindrical end of the turret-shaped ball pivot body. This stop means in conjunction with a stop means surface within the cylindrical recess of the coupling ball advantageously forms a defined and repeatedly accurate measurement for the bearing of the coupling ball with respect to the ball pivot body.
The bolt connection is advantageously formed by means of a threaded pin, which passes through a through hole in the ball pivot body, co-operates at one end with a threaded bore in the coupling ball, and on the side facing away from the coupling ball is secured by means of a threaded nut to the ball pivot body. The threaded bore in the coupling ball advantageously has in this connection a shoulder via which the threaded pin is screwed into the threaded bore, wherein the threaded bore is arranged within a thickened portion of material formed in the floor of the coupling ball, the said thickened portion being situated, in the installed state of the coupling ball, within a recess in the cylindrical end of the ball pivot body. The threaded nut is in turn advantageously arranged in the installed state likewise in a recess that is located on the side, facing away from the cylindrical end, of the ball pivot body. The threaded nut also has an extended load-bearing threaded region for a simplified installation and dismantling of the central coupling, the said threaded region in a preferred embodiment being located within an expanded region of the through hole. This arrangement permits a reduced installation space as regards height, since the bolt connection is arranged substantially completely within the structural parts to be joined, and in addition the coupling
ball has an enlarged overlapping with the turret-shaped ball pivot body. The extended load-bearing threaded region also advantageously increases the load-
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carrying capacity of the bolt connection. Furthermore, in an advantageous manner in the axial extension of the bearing shell there is a complete radial overlapping of the bearing surface between the bearing shell and coupling ball, with the contact surface of the coupling ball and the ball pivot body.
In order to improve the sliding properties between the bearing shell and coupling ball, a sliding layer, for example of plastics material, can be arranged between the bearing shell and the coupling ball.
Advantageously the bearing shell is arranged free of play in the coupling housing by means of a securement ring conically shaped on at least one side, which securement ring engages in the housing in a groove having a conical shape on at least one side.
The invention will be described in more detail hereinafter with the aid of an embodiment, and with reference to the accompanying drawing, in which:
Fig.l is a sectional view of a central coupling for a wishbone for a vehicle.
Fig. 1 is a sectional view of a central coupling 1 of a wishbone, which connects two struts 2 (here only one strut is shown) together via a coupling housing 3. The coupling housing 3 constructed of a coupling housing body 4 and a coupling housing floor 5 is formed as one piece, for example of a cast metal material. A ball pivot 6 is rotatably and swivellably arranged in the coupling housing 3, the ball pivot 6 comprising a coupling ball 7 and a ball pivot body 8. The ball pivot body 8 has a cylindrical end 9 that is inserted into a similarly cylindrical recess 10 of the coupling ball 7. In this connection the cylindrical end 9 of the ball pivot body 8 has a larger diameter than the cylindrical recess 10 of the coupling ball 7, so that a press fit exists between the coupling ball 7 and the ball pivot body 8. Instead of the cylindrical shape of the recess 10 and of the end 9 of the ball pivot body 8, any other interlocking-type connection can also be chosen, for example a polygonal (hexagonal, octagonal, etc.) interlocking-type connection.
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The coupling ball 7 and the ball pivot body 8 are joined to one another by means of a bolt connection 11. The bolt connection 11 is in this case formed from a threaded pin 12 that passes through a through hole 13 of the ball pivot body 8 and is screwed into a threaded bore 14 in the coupling ball 7 until it strikes a stop means 15 within the threaded bore 14, as well as from a threaded nut 16, which, on the side of the ball pivot body 8 facing away from the coupling ball 7, is screwed onto the threaded pin 12 and bolted against the ball pivot body 8. The coupling ball 7 is thus mounted on the ball pivot body 8, and specifically in such a way that the coupling ball 7 together with its coupling ball floor 17 comes to rest against a, for example, face-turned front surface 18 of the cylindrical end 9 of the ball pivot body 8. In this way an always
repeatable and very accurately measurable installation is ensured.
The threaded nut 16 has an extended load-bearing threaded region 19, which in the installed state is arranged in a region 20 of enlarged diameter of the through bore 13.
The threaded bore 14 is arranged within a thickened portion of material 21 of the coupling housing floor 17, the thickened portion of material 21 in turn, in the assembled state, being arranged within a recess 22 of the ball pivot body 8. In the installed state the threaded nut 16 is arranged in a further recess 23 of the ball pivot body 8, arranged on the side of the ball pivot body 8 facing away from the recess 22. Since the threaded pin 12 is not longer than the structure of the ball pivot body 8 and the coupling ball 7, the whole bolt connection 11 is arranged within the ball pivot 6, whereby overall a very compact structure is formed.
For the swivellable bearing of the ball pivot 6 in the coupling housing 3, a bearing shell 24, which in this embodiment preferably consists of a metallic material, is arranged between the coupling ball 7 and the coupling housing body 4. In order to improve the sliding properties an additional sliding layer 25, preferably of a plastics material, is provided on the bearing 24 and acts between the bearing 24 and the coupling ball 7. The bearing shell 24 is held by means of a conically shaped
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securement ring 26 in the coupling housing 3. The securement ring 28 engages in a groove 27 and has a conical outer surface 28 facing away from the bearing shell 24, which co-operates with a similarly conically shaped inner wall 29 of the groove 27, so that the bearing shell 24 is held free of play in the coupling housing 3.
The ball pivot body 8 has a flange 30 on which furthermore is arranged a centering shoulder 31 for the accurate positioning of the central coupling 1 on an axle. A sealing bellows 32 is furthermore provided between the flange 30 and coupling housing 3. The space 33 enclosed by the sealing bellows 32, as well as the space 34 remaining between the coupling ball floor 17 and the coupling housing floor 5, can be filled with a lubricant.
Since the cylindrical end 9 of the ball pivot body 8 penetrates a long way into the recess 10 of the coupling ball 7, and more specifically as far as the pivot ball floor 17, in the axial extension there is a radial overlapping of the working surface and frictional surface between the bearing shell 24 and the coupling ball 7, with the contact surface between the coupling ball 7 and the cylindrical end 9 of the ball pivot body 8. This contributes to an improved transmission of the acting forces between the coupling housing 3 and the ball pivot 6. In addition, due to this type of connection of the coupling ball 7 and ball pivot body 8, the coupling ball 7 is radially uniformly expanded for example by a uniform press-fit connection over the axial extension of the cylindrical connection, so that the pretensioning between the bearing shell 24 and the coupling ball 25 is also uniformly distributed over the area of the bearing shell 24.
In a first work stage the sliding layer 25 is mounted, for example bonded, to the bearing shell 24. The thus prefabricated bearing shell 24 is then reverse drawn over the coupling ball 7 and pressed against the coupling ball 7, so that the bearing shell 24 rests against the coupling ball 7. The bearing shell 24 is then shaped onto the coupling ball 7. This forming operation may for example however also only take
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place when the bearing shell 24 together with the coupling ball 7 is inserted into the coupling housing 3. In a next work stage a heat treatment is carried out, in which the sliding layer 25, consisting in this embodiment of a plastics material, is "baked out", i.e. the sliding layer 25 receives, at certain temperatures depending on the parameters of time and pressure, its final strength, frictional and wear resistance properties.
The thus pre-assembled unit consisting of coupling ball 7 and bearing shell 24 is now pressed into the coupling housing 3 until it rests against a bearing on a housing shoulder 35. The bearing shell 24 is then fixed in a play-free manner in the coupling housing by means of the conically shaped securement ring 26 inserted into the groove 27. First of all the threaded pin 12 is now screwed into the threaded bore 14 as far as the stop means 15, which is formed for example by a deformation of the threads, and in a further work stage the sealing bellows 32 are fastened to the coupling housing 3, if necessary with further ancillary means such as for example securement rings or clamps, which are not shown in more detail here.
The ball pivot body 8 is now inserted over the threaded pin 12. The threaded nut 16 is next screwed onto the threaded pin 12 until it comes to rest against the ball pivot body 8. This work stage may be carried out for example manually. When the threaded nut 16 is turned on the threaded pin 12, first of all the extended threaded region 19 of the threaded nut 16 is screwed onto some threads on the threaded pin 12. The threaded pin 12 in the case where the ball pivot body 8 is simply attached to the threaded ball 7, is still located completely in the through bore 13, and only the end of the threaded pin 12 facing towards the threaded nut 16 comes to rest in the region 20 of greater diameter, of the through bore 13, so that the threaded nut 16 can engage the threaded pin 12. The threaded nut 16 is now turned further using a tool, so that the ball pivot body 8 is drawn into the recess 10 of the coupling ball 7 until the front surface 18 of the ball pivot body 8 comes to rest against the coupling ball floor 17. Here the threaded nut 16 is tightened, after allowing for torque. Finally, the sealing bellows 32 are secured by means of, for example, a clamp (not shown
8

here) to the flange 30 of the ball pivot body 8 and the central coupling 1 is if necessary filled with a lubricant.
On account of the extended threaded region 19 of the threaded nut 16, which in the installed state is arranged within the ball pivot body 8, the threaded pin can be made extremely short. In this way it is possible to keep the installation height of the central coupling 1 low, and to assemble the central coupling 1 overall in an extremely compact manner.
The thus assembled central coupling 1 forms together with the struts 8 a structural unit that can be mounted via the centering shoulder 31 on an axle.
The installation sequence described here expressly represents only one possible sequence of the work steps for assembling the central coupling 1. Installation sequences differing from this may obviously be conceived and can also be implemented.
Due to the one-piece design of the coupling housing 3, in the region of the coupling housing floor 5 no sealing problems arise as regards the coupling housing body 4, since there are no sealing joints in this region. Also, additional structural parts, for example connecting elements such as bolts or rivets and sealing rings, can be completely avoided. The casting of the coupling housing 3 illustrated in the embodiment is simply one possible variant of the one-piece implementation. In addition it is obviously also conceivable to connect the coupling housing floor 5 to the coupling housing body 4 by means of a weld joint, or to machine the coupling housing 3 in one piece or to forge the housing.
9

References

1 Central coupling
2 Strut
3 Coupling housing
4 Coupling housing body
5 Coupling housing floor
6 Ball pivot
7 Coupling ball
8 Ball pivot body
9 Cylindrical end of the ball pivot body
10 Cylindrical recess
11 Bolt connection
12 Threaded pin
13 Through bore
14 Threaded bore
15 Stop means
16 Threaded nut
17 Coupling ball floor
18 Front surface
19 Extended threaded region
20 Region of enlarged diameter
21 Thickened portion of material
22 Recess
23 Recess
24 Bearing shell
25 Sliding layer
26 Securement ring
27 Groove
28 Conical outer surface
29 Conical inner wall
10

30 Flange
31 Centering shoulder
32 Sealing bellows
33 Space
34 Space
35 Housing shoulder

11

WE CLAIM:
1. Central coupling (1) for a wishbone of vehicles, in particular commercial
vehicles, with a ball pivot (6) accommodated in a bearing housing (3), wherein
the bearing housing (3) is formed of a bearing housing body (4) and a
bearing housing floor (5), and
the ball pivot (6) is formed of a turret-shaped ball pivot body (8) and a
coupling ball (7) mounted on the ball pivot body (8), and
the ball pivot (6) is swivellably and rotatably mounted in a bearing
shell (24) fixed in the coupling housing (7),
characterised in that
the coupling housing (3) is formed in one piece from the coupling
housing body (4) and the coupling housing floor (5).
2. Central coupling for a wishbone according to claim 1, characterised in that the coupling ball (7) is connected to the ball pivot body (8) by means of a bolt connection (11).
3. Central coupling for a wishbone according to claim 1 or 2, characterised in that the ball pivot body (8) is cylindrically formed on its end (9) facing towards the coupling ball (7) wherein this end (9) is inserted into a similarly cylindrically shaped recess (10) of the coupling ball (7).
4. Central coupling for a wishbone according to claim 1 or 2, characterised in that the ball pivot body (8) and the coupling ball (7) are in mutual engagement via an interlocking connection, in particular a notched tooth profile or a polygonal profile.
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5. Central coupling for a wishbone according to claim 3, characterised in that the cylindrical end (9) of the ball pivot body (8) with a front surface (18) forms a stop means for accommodating the coupling ball (7).
6. Central coupling for a wishbone according to claim 3, characterised in that the diameter of the cylindrical end (9) of the ball pivot body (8) is larger than the internal diameter of the cylindrical recess (10) of the coupling ball (7).
7. Central coupling for a wishbone according to claim 3 or 4, characterised in that a press-type connection acts between the ball pivot body (8) and the coupling ball (7).
8. Central coupling for a wishbone according to claim 2, characterised in that the bolt connection (11) is formed by a threaded pin (12) which passes through a through bore (13) of the ball pivot body (8), co-operates at one end with a threaded bore (14) in the coupling ball (7) and is secured, on the side of the ball pivot body (8) facing away from the coupling ball (7), with a threaded nut (16) to the ball pivot body (8).
9. Central coupling for a wishbone according to claim 8, characterised in that the threaded bore (14) in the coupling ball (7) has a stop means (15), against which is screwed the threaded pin (12) in the threaded bore (14).
10. Central coupling for a wishbone according to claim 8, characterised in that the threaded bore (14) is arranged in the region of a thickened portion of material (21) of a coupling ball floor (17) of the coupling ball (7), wherein the ball pivot body (8) has at its cylindrical end (9) a recess (22) within which the thickened portion of material (21) is preferably arranged in the installed state.
11. Central coupling for a wishbone according to claim 8, characterised in that the threaded nut (16) has an extended threaded region (19).
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12. Central coupling for a wishbone according to claim 8 or 11, characterised in that the threaded nut (16) in the assembled state is arranged substantially within a recess (23) of the ball pivot body (8).
13. Central coupling for a wishbone according to claim 2, characterised in that the extended load carrying threaded region (19) of the threaded nut (16) in the assembled state is arranged within a region of expanded diameter (20) of the through bore (13).
14. Central coupling for a wishbone according to claim 1, characterised in that the ball pivot (6) has at its end facing away from the coupling ball (7), a flange (30) with a centering shoulder (31).
15. Central coupling for a wishbone according to claim 1, characterised in that a sliding layer (25), preferably of a plastics material, is arranged between the bearing shell (24) and the coupling ball (7).
16. Central coupling for a wishbone according to claims 1 to 12, characterised in that the bearing shell (7) is arranged in a manner free of play in the coupling housing (3) by means of a securement ring (26), formed having a conically shaped outer surface (28) on at least one side, which ring engages in the coupling housing (3) in a groove having an inner wall (29) that is conically shaped on at least one side.
Dated this 11th day of December, 2006.
HIRAL CHANDRAKANT JOSHI - AGENT FOR
ZF FRIEDRICHSHAFEN AG
14

Abstract
Central coupling 1 for a wishbone of vehicles, in particular commercial vehicles, with a ball pivot 6 accommodated in a coupling housing 3, wherein the coupling housing 3 is formed from a coupling housing body 4 and a coupling housing floor 5, and the ball pivot 6 is formed from a turret-shaped ball pivot body 8 and a coupling ball 7 mounted on the ball pivot body 8, and the ball pivot 6 is swivellably and rotatably mounted in a bearing shell 24 secured in the coupling housing 3. The invention is characterised in that the coupling housing 3 is formed in one piece from the coupling housing body 4 and the coupling housing floor 5.
To
The Controller of Patents
The Patent Office
Mumbai

Documents:

1520-mumnp-2006-abstract(05-03-2008).doc

1520-mumnp-2006-abstract(05-03-2008).pdf

1520-mumnp-2006-abstract.doc

1520-mumnp-2006-abstract.pdf

1520-mumnp-2006-cancelled pages(05-03-2008).pdf

1520-mumnp-2006-claims(granted)-(05-03-2008).doc

1520-mumnp-2006-claims(granted)-(05-03-2008).pdf

1520-mumnp-2006-claims.doc

1520-mumnp-2006-claims.pdf

1520-mumnp-2006-correspondence(05-03-2008).pdf

1520-mumnp-2006-correspondence(ipo)-(08-09-2008).pdf

1520-mumnp-2006-correspondence-received.pdf

1520-mumnp-2006-description (complete).pdf

1520-mumnp-2006-drawing(05-03-2008).pdf

1520-mumnp-2006-form 1(05-03-2008).pdf

1520-mumnp-2006-form 18(12-12-2006).pdf

1520-mumnp-2006-form 2(granted)-(05-03-2008).doc

1520-mumnp-2006-form 2(granted)-(05-03-2008).pdf

1520-mumnp-2006-form 26(12-03-2007).pdf

1520-mumnp-2006-form 3(05-03-2008).pdf

1520-mumnp-2006-form 5(05-03-2008).pdf

1520-mumnp-2006-form-1.pdf

1520-mumnp-2006-form-18.pdf

1520-mumnp-2006-form-2.doc

1520-mumnp-2006-form-2.pdf

1520-mumnp-2006-form-3.pdf

1520-mumnp-2006-form-5.pdf

1520-mumnp-2006-form-pct-ib-301.pdf

1520-mumnp-2006-form-pct-ib-304.pdf

1520-mumnp-2006-form-pct-ib-311.pdf

1520-mumnp-2006-form-pct-isa-210(05-03-2008).pdf

1520-mumnp-2006-form-pct-isa-237.pdf

1520-mumnp-2006-form-pct-ro-101.pdf

1520-mumnp-2006-pct search report.pdf

abstract1.jpg


Patent Number 223216
Indian Patent Application Number 1520/MUMNP/2006
PG Journal Number 06/2009
Publication Date 06-Feb-2009
Grant Date 08-Sep-2008
Date of Filing 12-Dec-2006
Name of Patentee ZF FRIEDRICHSHAFEN AG
Applicant Address 88038 FRIEDRICHSHAFEN, GERMANY
Inventors:
# Inventor's Name Inventor's Address
1 KUNZE RALF KIRCHBREITE 12, 49152 BAD ESSEN, GERMANY
2 KNOPP SOREN GROSSE HEIDE 26, 49179 OSTERCAPPELN GERMANY
3 BUHL MANFRED FELDSTRASSE 30, 49143 BISSENDORF, GERMANY
PCT International Classification Number F16C11/06
PCT International Application Number PCT/DE05/001010
PCT International Filing date 2005-06-08
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 102004029581.6 2004-06-18 Germany