Support arrangement for radius arms

A support arrangement for radius arms has an outer support arrangement part, an inner support arrangement part, an elastomer body located between the outer and inner support arrangement parts and a stop located at one end of one of the support arrangement parts to limit relative motions of the outer and inner support arrangement parts in one direction of a support arrangement center line. The stop has a centering surface concentric with the center line of the support arrangement part carrying the stop and facing towards the support arrangement part arranged to be brought into contact therewith. The centering surface, in a predetermined position of the support arrangement parts, is at a distance from the end of the adjacent support arrangement part.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a support arrangement for radius arms, 
and, more particularly, to a support arrangement comprising an outer 
support arrangement part, an inner support arrangement part, an elastomer 
body located between the outer and inner support arrangement parts and 
having a stop located at one end of one of the support arrangement parts 
to limit relative motions of the outer and inner support arrangement parts 
in one direction of a support arrangement center line, which stop has a 
centering surface concentric with the center line of the support 
arrangement part carrying the stop and facing towards the support 
arrangement part arranged to be brought into contact therewith, which 
centering surface, in a predetermined position of the support arrangement 
parts, is at a distance from the end of the adjacent support arrangement 
part. 
Support arrangements are shown in DE 40 17 275 A1 and DE 34 18 006 C2. An 
elastomer body provides these support arrangements with stiffness such 
that, when the vehicle is being driven, there is effective damping of 
wheel longitudinal vibrations and shocks acting on the vehicle wheel in 
the longitudinal direction of the vehicle. The stop associated with one 
end of the inner support arrangement part is used to limit the axial 
displacement in the direction of travel of the inner and outer support 
arrangement parts relative to one another in the case of extremely severe 
impacts directed onto the vehicle wheel in the longitudinal direction of 
the vehicle. If the side forces to which such support arrangements are 
matched are exceeded, such support arrangements permit an unallowable 
elastokinematic change to the axle half affected. 
In addition to the configuration shown in the patent publications already 
mentioned, which configurations form the starting point for the present 
invention, support arrangements with a stop having a centering surface are 
also known from DE-AS 23 42 990 and JP 2-38118 (A). In these arrangements, 
however, the stop and one of the support arrangement parts support 
themselves on one another continuously so that, under the action of 
extreme longitudinal and transverse forces, no mutual displacement of the 
two support arrangement parts such as to provide a positive correction to 
their radial displacement will occur. Also, FIGS. 12 and 13 of DE 36 19 
755 A1 finally show further technological background of the present 
invention. 
It is an object of the present invention to provide an elastic support 
arrangement of a configuration of the type mentioned at the outset which, 
even under the effects of extreme force at right angles to the support 
arrangement center line, permits only such elastokinematic changes to the 
axle half as are still desirable or defined and which, in the case of 
corresponding, mutually superimposed longitudinal and lateral forces, 
operates so as to correct the mutual displacement, resulting from these 
forces, of the two support arrangement parts relative to one another. 
The foregoing object has been achieved in accordance with the present 
invention by providing the centering surface of the stop has an annular 
groove narrowing conically inwardly and accommodating an end of the 
support arrangement part to be centered, and a groove bottom of the 
annular groove forms a centering bed. 
Equipping the stop with an annular groove formed in the centering surface 
and forming a centering bed offers the advantage that a relative radial 
displacement between the two support arrangement parts can then only take 
place to a defined extent under the action of lateral or radial forces. 
If, in addition to forces acting at right angles to the support arrangement 
center line, axially directed forces are also transmitted to the support 
arrangement, the end of one support arrangement part, which is being 
displaced in the direction towards the stop, is caused to be displaced 
during this axial displacement by the outer peripheral surface of the 
inwardly conically narrowing annular groove in the stop so as to align the 
two support arrangement parts coaxially relative to one another in a 
direction opposed to the effective force directed transversely to the 
support arrangement center line. 
Given a sufficiently large axial force, complete compensation will then be 
provided by the centering bed of the annular groove for any initial radial 
displacement of the two support arrangement parts relative to one another 
(i.e., track stabilization).

DETAILED DESCRIPTION OF THE DRAWINGS 
The support arrangement 10 of FIG. 1 is used to support a radius arm 12, 
for example a transverse arm, semi-trailing arm or trailing arm of an 
independent wheel suspension, on the superstructure. The support 
arrangement can be of any known type and can, for example, be configured 
as a torsional support arrangement or a sliding support arrangement. In 
the embodiment of FIG. 1, it is deemed advantageous to make it a hydraulic 
support arrangement. 
The arrangement includes an outer cylindrical support arrangement part 14 
fastened to the radius arm 12, an inner support arrangement part 18 
located on a hinge pin (not shown for clarity) which is accommodated in a 
support frame 16 fixed to the superstructure, and a rubber body 24 with, 
for example, two mutually opposite chambers 20, 22 connected by at least 
one damping passage (not shown) and containing damping fluid. The rubber 
body 24 is vulcanized between the sleeve-shaped, inner support arrangement 
part 18 and a sheet-metal cover 26 pressed into the outer support 
arrangement part 14. 
A metal sleeve 32 penetrated by window-type openings 28, 30 is also 
vulcanized in known manner into the rubber body 24 in the region of its 
two chambers 20, 22. At one of the ends of the support arrangement, the 
metal sleeve 32 has a flange 34 which protrudes radially beyond the end of 
the support arrangement and is supported on the end of the outer support 
arrangement part 14 to form an assembly stop. 
The inner, sleeve-shaped support arrangement part 18 is fixed in the axial 
direction between the arms 36, 38 of the U-shaped support frame 16 by a 
hinge pin formed in conventional manner by a clamping bolt (not shown for 
clarity) whereas the outer support arrangement part 14, together with the 
radius arm 12, is flexibly held axially and radially relative to the inner 
support arrangement part 18 via the rubber body 24. 
The outer support arrangement part 14 is associated with a stationary stop 
40 formed by a shaped disc placed on one end of the inner, cylindrical 
support arrangement part 18 and is axially fixed between the latter and, 
for example, the arm 36 of the support frame 16. This arrangement provides 
a substantially larger support base compared with the comparable end of 
the inner support arrangement part 18. In order to create a 
correspondingly large support base at the other end of the inner support 
arrangement part 18, a support disc 42 is preferably also applied to this 
other end of the inner support arrangement part 18, where it is clamped 
between the support arrangement part 18 and the arm 38 of the support 
frame 16. 
On its end facing towards the support arrangement 10, the shaped disc 
forming the stop 40 has, formed concentrically within it, an annular 
groove 44 whose groove walls 46, 48 form, together with the groove bottom 
50, a centering surface 52. 
The annular groove 44 permits the stop 40 to fit over the end 14', facing 
towards the stop 40, and, in the initial or design position of the two 
support arrangement parts 14, 18 (FIG. 1), the surface parts formed by the 
outer and inner groove walls 46, 48 of the centering surface 52, on the 
one hand, and the end 14' of the outer support arrangement part 14, on the 
other hand, are spaced apart laterally and radially. 
The annular groove 44 narrows conically towards the inside and its groove 
bottom 50 forms a bed for centering the end 14' of the outer support 
arrangement part 14. The end 14' which has to be centered preferably forms 
an annular bead curved convexly in the direction of the shaped disc. 
It is assumed that the support arrangement 10 is used for hinging to the 
superstructure the radius arm 12 forming a transverse arm and that the 
superstructure-end geometrical center line 58 of the support arrangement 
extends in the longitudinal direction of the vehicle. 
If the arrangement involves, for example, a lower transverse arm, the outer 
support arrangement part 14 of the radius arm support arrangement 10 at 
the superstructure end is displaced radially in the direction of the arrow 
F1 (FIG. 2) during vehicle braking procedures because of a moment caused 
by the braking force at the hinge point of the transverse arm 12 at the 
wheel support end. This support arrangement part 14 simultaneously 
experiences a displacement in the axial direction of the support 
arrangement against the direction of travel shown by arrow F. 
The contour shown in the support arrangement longitudinal section of the 
disc-shaped stop 40 ensures that these displacements can only take place 
to a defined extent. The radial motion of the transverse arm 12 is 
initially limited at the support points 60, 62. A motion of the outer 
support arrangement part 14 caused by the centering surface 52 can take 
place simultaneously, depending on the longitudinal force, so that the 
bead-shaped end 14' of the support arrangement can be guided into the 
centering bed formed by the groove bottom 50 until it is again centered, 
relative to the inner support arrangement part 18, on the groove bottom 50 
(FIG. 3). The outer support arrangement part 14 is therefore forced into 
its original center line position by the effects of braking forces. The 
support arrangement 10 has, in consequence, a self-correcting action. 
In order to minimize the friction between the end 14' of the support 
arrangement part and the corresponding wall parts of the annular groove 44 
during braking and movements of the suspension system and to prevent the 
entry of impurities, an annular, flexible sealing element 56 is inserted 
into the end wall part 54 of the stop 40 formed by a shaped disc, the part 
54 forming the radially outer limit of the annular groove 44. This 
flexible sealing element 56 surrounds the end 14', configured as an 
annular bead, at its periphery so as to provide a seal. It is therefore 
possible to fill the space between the end 14' of the support arrangement 
part and the annular groove 44 with a lubricant. 
As a modification to the embodiment of FIG. 1, the stop 40 can also be 
provided on the outer support arrangement part 14 and the end of the 
support arrangement part interacting with its centering surface 52 can be 
provided on the inner support arrangement part 18. 
Furthermore, in the case of triangular or semi-trailing arms, it is 
possible for only one or both of their radius arm support arrangements to 
have the configuration according to the invention at the superstructure 
end. Finally, in the case of double transverse arm wheel suspensions, the 
support arrangement configuration according to the present invention can 
be provided on the lower or the upper transverse or semi-trailing arm or 
on both transverse or semi-trailing arms. 
In the support arrangement embodiment shown in FIG. 4, the stop 40 is 
arranged so as to be axially displaceable on a hollow cylindrical end 
piece 80' of the inner bush-type support arrangement part 80 protruding 
from the torsional support arrangement 78 fixed axially in the support 
frame 16. The stop 40 is supported, at one end, on an elastic support ring 
82 at the support arrangement end and, at the other end by an end collar 
84 on an adjusting nut 86 which is rotatable on a threaded bush 88 axially 
fixed on the end piece 80' of the inner support arrangement part 80. The 
adjusting nut 86 is arranged so that it can be fixed by a fixing screw 90 
which protrudes into the collar 84. 
The adjusting nut 86 permits the vehicle stability to be improved in an 
optimum manner during braking procedures by way of a variable path 
limitation of the outer support arrangement part 81. In addition, this 
adjustment possibility permits the radial support arrangement stiffness to 
be increased by reducing the axial path of the outer support arrangement 
part 78. 
A further improvement to the radius arm support arrangement equipped with 
an axially adjustable stop 40 can be seen in FIG. 4. This consists in 
arranging the axial and radial motion limitations of the outer support 
arrangement part 81 as a function of brake pressure. 
For this purpose, an inner section of the stop collar 84 forms, together 
with the end piece 88' of the threaded bush 88 (which end piece 88' 
protrudes into the stop collar 84 so as to form a seal), a pressure space 
92 which is filled with brake fluid and is connected to a main brake 
cylinder 98 via a connecting conduit 94 with a pressure reducing valve 96 
fitted between. 
A certain fluid pressure can, for example, be branched off from the braking 
system of the motor vehicle via the pressure reducing valve 96 and after 
the conclusion of the braking procedure, this pressure can be reduced 
again by a reservoir 100 of the brake circuit. 
During a braking procedure, some of the brake fluid is forced via the 
pressure reducing valve 96 between the stop 40 and the bush end piece 88', 
the stop 40 being displaced axially in the direction of travel F and the 
radius arm 12 carrying the support arrangement 78 being displaced axially 
against the direction of travel F. 
Because that the brake hydraulic system will reacts substantially more 
rapidly than the radius arm 12 overcomes the support arrangement 
stiffnesses, the displacement time is shortened and the stop 40 is 
correspondingly displaced axially in the direction towards the support 
arrangement. As a result, the radius arm displacement is correspondingly 
and prematurely shortened axially and radially and the desired 
stabilization of the vehicle is correspondingly further improved. 
Brake fluid from both the front axle circuit and the rear axle circuit can 
be diverted for the generation of pressure in the annular pressure space 
92. 
In the design position of the radius arm support arrangement 78, the 
support ring 82 forming a soft rubber buffer provides compensation for 
tolerances between the stop 40 and the inner support arrangement part 80 
and this simultaneously prevents impact noises during axial displacement 
of the stop 40. 
FIG. 5 shows a way of hydraulically controlling the stop arrangement 
(explained using the embodiment of FIG. 4) as a function of one or more 
vehicle operating parameters in addition, if need be, to its being 
controlled as a function of brake pressure. The stop 40 can be controlled 
by an auxiliary pressure source indicated overall by 102. For example, the 
pressure source 102 includes a pressure reservoir 106 which is connected 
to the pressure outlet 104, charged to a minimum pressure level and 
configured as a hydro-pneumatic spring. The pressure reservoir 106 can be 
charged by a reservoir charging pump 108 via a non-return valve 110, 
controlled by a pressure monitor 112. The maximum output pressure of the 
pressure reservoir 106 and of the auxiliary pressure source 102 is limited 
by a pressure limiting valve 114. 
A supply conduit 116 which can be connected to the pressure space 92 is the 
outlet 104 and a control valve 120 (3/2-way valve), which can be triggered 
by a control device 118, is connected into this supply conduit 116. A 
return conduit 122 leads from this control valve 120 to an unpressurized 
reservoir 124 of the auxiliary pressure source 102. 
The control device 118 can, for example, process a plurality of control and 
vehicle operating parameters to provide control signals for triggering the 
control valve 120. These parameters are determined by sensors installed in 
the vehicle. As examples, a sensor 126 can determine the braking 
deceleration, a sensor 128 can determine the vehicle speed and a sensor 
130 can determine the steering rate or steering angle. 
Individual control parameters can be processed in the control device 118 or 
a plurality of control parameters appearing in the control device 118 can 
be processed simultaneously by association of control signals. 
The stop 40 is therefore, for example, automatically displaced 
appropriately in the direction of travel F when the vehicle is travelling 
around a curve so that in the case of transverse or semi-trailing arms, 
complete compensation is provided, if necessary, for the radial 
displacement of the outer support arrangement part 81 taking place as a 
function of the side force and the vehicle can be stabilized because with 
the control valve 120 driven into the through position shown, the radius 
arm radial path is immediately shortened appropriately by the stop 40. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.