FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION (See Section 10, and RULE13
1. TITLE OF INVENTION
WHEEL-GUIDING STABILISER DEVICE

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 : -


Description
The invention relates to a stabiliser device for a vehicle axle with a roll stabiliser according to the preamble of Claim 1.
Vehicle axles according to the preamble, in the case of which the roll stabiliser is actuated directly by a wheel control arm connected to the roll stabiliser, for example by a torsion strut or a compression strut of the wheel suspension, are in the first place advantageous in so far as a stabiliser transmission ratio of 1:1 in particular can be achieved in this way. In other words, this means that the deflection movements of the wheel are not converted just proportionally, but rather in each case fully into a corresponding torsional movement of the stabiliser, which is why, for example, stabilisers which are correspondingly thinner or have thinner walls and are therefore lighter can be used. Moreover, the mounting of the stabiliser can thus also be of a more flexible and therefore comfortable design, yet without impairing the response behaviour.
Furthermore, this type of design lacks both the usual articulations of the stabiliser ends in each case via an individual pendulum support with two ball-and-socket joints and also the usual angular stabiliser legs, whereby weight is also saved and in addition a considerable amount of valuable construction space is liberated.
However in the case of the wheel-controlling stabiliser devices according to the preamble, as are known, for example, from DE 10 2004 020 073 Al or from EP 1 564 041 A2, significant structural conflicts of goals occur in the region of the connection between the chassis-side end of the wheel control arm and the respective associated end of the stabiliser. For it is precisely in this region that contradictory structural requirements of the otherwise separate components "wheel control arm" or "tension strut/compression strut" and "roll stabiliser", which a stabiliser according to the preamble still has to fulfil, meet one another.
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The functions and requirements which are relevant in this respect include in particular the most direct conversion possible of the deflection movements of the wheel into corresponding torsional movements of the stabiliser, also the transmission of force from the wheel carrier to the chassis or to the axle carrier, as well as the flexibility and vibration damping, specifically required in each case, over the distance between the wheel carrier and axle carrier or chassis.
The particular problem which arises when combining the stabiliser and the wheel control arm to form the wheel-controlling stabiliser device according to the preamble is that, although soft rubber bearings and correspondingly high flexibility in the region of the chassis-side connection of the wheel control arm to the axle carrier are advantageous for a comfort mounting with good acoustic damping, at the same time they have disadvantageous effects on the response behaviour of the stabiliser. With regard to the coupling of the wheel control arm to the stabiliser end, a further aggravating factor is that the rotational axis of the stabiliser extends in the transverse direction of the vehicle, while the rotational axes of wheel control arms, in particular the rotational axes of the tension struts or compression struts in question, generally extend at an acute angle to the longitudinal axis of the vehicle.
The connecting region between the stabiliser end, the chassis-side end of the wheel control arm and the chassis or axle carrier must therefore guarantee, as far as possible, that the wheel forces are introduced into the chassis with a defined softness and vibration damping, although also a direct conversion, undamped as far as possible, of the wheel deflection into the stabiliser twisting, while at the same time also permitting the angular variations between the longitudinal axis of the wheel control arm and the rotational axis of the stabiliser occurring upon deflection.
Against this background, the object of the present invention is to provide a wheel-controlling stabiliser device with which the above-mentioned advantages which are found in the prior art are overcome. The stabiliser device should in this respect in particular lead to advantages regarding comfort properties, acoustics and structure-
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borne sound isolation of the running gear with a direct response of the stabiliser at the same time. A further aim is to achieve improvements in terms of the construction space required for the stabiliser device, with regard to weight saving as well as in relation to improved modularity in connection with use in wheel suspensions and axle systems.
This object is achieved by a stabiliser device having the features of Claim 1.
Preferred embodiments constitute the subject matter of the subclaims.
In a manner which is in the first place known per se the stabiliser device according to the invention is intended for use on a vehicle axle with a roll stabiliser, wherein the axle has at least one wheel control arm for each wheel. In this respect, in a manner which is likewise known per se, the chassis-side articulation of the wheel control arm is connected to the associated end region of the roll stabiliser such that twisting actuation of the roll stabiliser takes place through deflection movements of the wheel control arm.
According to the invention, however, the stabiliser device is distinguished by the fact that the roll stabiliser is accommodated at the ends in a respective shaft which is connected to the wheel control arm and is at least partly hollow. Here this hollow shaft is mounted in a chassis-side bearing carrier, the bearing carrier being resiliently connectable to the vehicle, for example to an axle carrier of the vehicle.
The accommodation of the stabiliser ends in each case in a hollow shaft resiliently mounted on the chassis side is in the first place advantageous in so far as in this way the stabiliser no longer has to be bent, in particular not in the region of its ends. On account of the hollow shaft, which, according to the invention, takes over the function of connecting the stabiliser end to the vehicle-side end of the wheel control arm, the ends of the stabiliser can in this way rather be of bar-shaped straight construction, whereby the stabiliser device according to the invention is in
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particular, although by no means exclusively, suitable for the very light, although structurally exacting, tube stabilisers.
In addition, on account of the hollow shaft, the entire length of the stabiliser - or the entire width of the stabiliser device - can also be fully utilised in a structurally desirable manner as the effective stabiliser torsional length. This also results in an arrangement of the mounting of the hollow shaft and of the connection between the stabiliser end and the wheel control arm which in particular saves construction space overall.
Moreover, on account of the bearing carrier, optimum isolation of the entire module consisting of the stabiliser, hollow shaft and wheel control arm in relation to vibrations and the transmission of sound with respect to the vehicle chassis can take place, although at the same time the wheel control arm acts inflexibly on the hollow shaft or on the stabiliser and therefore guarantees a direct response of the stabiliser during deflection movements of the wheel.
Finally, even further advantages are achieved which relate in particular to the possibility of simple manufacture and uncomplicated assembly of the entire stabiliser device as an axle part module on the vehicle.
The invention is in the first place implemented irrespective of the structural form of the resilient connection of the bearing carrier to the vehicle chassis or axle carrier. According to one preferred embodiment, however, the resilient connection of the bearing carrier has an at least twice as high spring rate in the z direction (that is along the vertical axis of the vehicle) as in the x direction (longitudinal axis of the vehicle) or y direction (transverse axis of the vehicle). Good comfort properties relating to the undesirable transmission of sound and vibrations occurring in particular along the longitudinal axis of the wheel control arm are in this way achieved, with a direct response of the stabiliser being guaranteed at the same time on account of the high spring rate in the z direction,
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In this respect the bearing carrier is preferably resiliency connected to the axle carrier or to the vehicle chassis by elastomer bearings or hydro bearings, which have to a large extent proved successful for the purpose of vibration damping and sound absorption at the vehicle.
According to one particularly preferred embodiment of the invention, the elastomer bearings or hydro bearings are disposed centrosymmetrically in relation to the point of intersection of the longitudinal axes of the wheel control arm and the hollow shaft. This results in an optimally uniform introduction and distribution of the wheel forces from the wheel control arm into and among the individual bearing points. Since, according to this embodiment, the bearing points are disposed centrosymmetrically in relation to the effective force introduction point - which is located at the point of intersection of the longitudinal axes of the wheel control arm and the hollow shaft or stabiliser - no secondary moments are produced and therefore there is also no kind of undesirable tilting of the bearing carrier with respect to the chassis or with respect to the axle carrier upon the introduction of force.
The invention can be implemented irrespective of the specific form of the roll stabiliser, as long as the end regions of the stabiliser can be accommodated in the hollow shaft. According to one particularly preferred embodiment, however, the roll stabiliser is substantially formed by a straight bar or by a straight tube. This results in particularly inexpensive manufacture and the lowest possible weight as well as optimum utilisation of material, as in this way the entire length of the stabiliser is subject to a completely uniform torsional load. Moreover, the stabiliser device can this way be controlled particularly accurately in structural terms, and the stabiliser device is in addition easily assembled as a modular unit.
In a further embodiment of the invention the roll stabiliser consists of two separate stabiliser halves. In this case an actuator for active relative twisting of the stabiliser halves with respect to one another can be disposed between the stabiliser halves. In
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this way controlling torques or controlling forces can be produced between the wheel suspension and the vehicle structure or introduced into the wheel suspension in the direction of the active running gear. It is thus possible, for example, for active roll stabilisation of the vehicle to take place when taking a corner, or the effective hardness of the roll stabiliser can be varied in accordance with the running condition of the vehicle.
However the term "stabiliser halves" selected for reasons of descriptiveness should not in this respect be interpreted in a limiting sense to the effect that the two stabiliser halves must of necessity be of the same length. For the stabiliser halves can just as well be of different lengths, without the effectiveness or overall characteristic of an active roll stabiliser of this kind being changed by this.
Furthermore, in order to implement the invention, it is in the first place of no importance how the vehicle-side end of the wheel control arm and the hollow shaft are coupled together, as long as reliable transmission of torque with simultaneous variability of the angle between the longitudinal axis of the wheel control arm and the rotational axis of the hollow shaft is guaranteed.
According to one preferred embodiment of the invention, however, the wheel control arm is connected to the hollow shaft by means of two ball-and-socket joints. This is of advantage in so far as a play-free transmission of movement between the wheel control arm and the hollow shaft, or between the wheel control arm and the roll stabiliser, can thereby take place by means of the spherical head technique, which has proved successful in wheel suspensions. At the same time the degree of freedom of the swivelling movement between the wheel control arm and the hollow shaft, which is required during deflection or steering movements, is in this way provided with ease. Furthermore, a connection of this kind between the wheel control arm and the hollow shaft can be effectively controlled.largely maintenance-free as well as in structural terms while having a long service life.
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In this respect the centre points of the balls of the ball-and-socket joints are particularly preferably disposed on a diametral straight line of the hollow shaft. In this way an optimal introduction of torque with the lowest possible load on the ball-and-socket joints and at the same time with the optimal lever arm between the ball-and-socket joints and the hollow shaft is achieved.
According to a further, likewise preferred embodiment of the invention, the joint housings of the ball-and-socket joints are formed by the actual wheel control arm. This embodiment can in particular be in the form of a one-piece fork-like formation of the vehicle-side end region of the wheel control arm, in which case the joint housings of the ball-and-socket joints are formed by corresponding bores in the two fork ends of the wheel control arm, or are accommodated by these bores. An advantageous, cost-saving combination of functions accompanied by high stiffness and a small construction space requirement is in this way achieved.
According to the invention, the hollow shaft can in the first place be mounted in the bearing carrier in any desired manner, as long as the occurring wheel forces can be reliably transmitted from the wheel control arm via the hollow shaft to the bearing carrier. According to one preferred embodiment of the invention, however, the hollow shaft is mounted in the bearing carrier by means of a fixed/movable mounting. It is in this way possible to guarantee smooth operation and freedom from stress of the mounting under all temperature and load conditions, while a long service life which can be accurately controlled in structural terms can also be achieved through an appropriate design of the fixed/movable mounting.
The fixed bearing of the hollow shaft is in this case preferably formed by a sleeve joint. Sleeve joints are inexpensive and proven in the field of axle systems of motor vehicles. They are distinguished by a high load-bearing capacity, low-maintenance requirement, space-saving structure and in particular by problem-free accommodation of angular errors and shaft deflections.
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According to a further, particularly preferred embodiment of the invention, the wheel control arm connected to the roll stabiliser is a tension strut or compression strut of a wheel suspension. On account of the acute angle between the longitudinal axis of the strut and the direction of travel, tension struts and compression struts of wheel suspensions are particularly suitable for actuating the stabiliser, as in this way an almost 1:1 transmission ratio between the deflection-induced angular movement of the tension strut or compression strut and the corresponding twisting of the roll stabiliser can be achieved.
The invention is illustrated in detail in the following on the basis of drawings which simply represent embodiments and in which:
Fig.l
shows in a schematic representation the connection between the wheel control arm and the stabiliser end in an embodiment of a stabiliser device according to the invention in a plan view;
Fig. 2
shows in an isometric representation a schematic example of a wheel control arm for a stabiliser device according to the invention; and
Fig. 3 shows the connection between the wheel control arm and the stabiliser end according to Figure 1 in a vertical section.
Fig. 1 shows the connection between a wheel control arm 1 and the associated stabiliser end 2 in an embodiment of a stabiliser device according to the present invention in a plan view. The stabiliser end 2 on the left-hand side, related to the direction of travel, and the chassis-side end region of the associated wheel control arm 1 are represented in Figure 1. Here the direction of travel of the associated vehicle extends upwards in the drawing, as indicated by the dashed arrow D.
Figure 1 in the first place shows - in particular viewed together with Figure 3 - the end region on the left-hand side, related to the vehicle, of the roll stabiliser 2, here
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formed as a tube stabiliser, of the vehicle; also the chassis-side end region of a wheel control arm 1, which is likewise only represented in part and which in the present case is a tension strut of the wheel suspension of the left-hand front wheel of a motor vehicle.
The end of the roll stabiliser 1 which is represented in Figures 1 and 3 is accommodated in a bearing carrier 3 which is connected via two bearing points 4, 5 to the vehicle chassis, or to an axle carrier, which is not represented, of the vehicle. For the purpose of a light-weight construction, the bearing carrier 3 is in the form of a one-piece component of a light metal die casting and bears at 4 and 5 in each case a bearing point formed as an elastomer bearing or hydro bearing for connection to the vehicle chassis or to the axle carrier of the vehicle.
Whereas the entire arrangement consisting of the roll stabiliser 2 and the wheel control arm 1 is isolated from the vehicle chassis in terms of vibrations by means of the elastomer bearings 4, 5, a direct response of the roll stabiliser 2 is at the same time guaranteed on account of the inflexible connection, which is described in detail in the following, between the wheel control arm 1 and the roll stabiliser 2. In this respect it is in particular possible to tune the elastomer bearings 4, 5 to be soft in the x-y plane - i.e. in the plane of the drawing according to Figure 1 - in the sense of a comfort mounting, as it is in particular in this plane that the undesirable vibrations and transmission of sound occur, starting from the wheel carrier (not represented) and transmitted primarily in the longitudinal direction of the wheel control arm 1. However the elastomer bearings 4, 5 can at the same time be tuned to be a multiple harder in the z direction, i.e. along the vertical axis of the vehicle, than in the x-y plane, practically without any loss of comfort, in order thus to guarantee a particularly direct response of the roll stabiliser 2 upon the wheel executing deflection movements.
The mounting of the stabiliser end 2 is shown particularly clearly in the sectional representation according to Figure 3, which is turned through 90° with respect to the
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longitudinal axis of the roll stabiliser 2 in comparison with the representation according to Figure 1. The viewing direction in the representation according to Figure 3 therefore extends horizontally in the direction of travel of the motor vehicle. It can be seen on the basis of the sectional representation in Figure 3 that the end of the roll stabiliser 2, which is in the form of a hollow tube, is in turn accommodated in a hollow shaft 6. In the represented embodiment the rotationally rigid connection between the hollow shaft 6 and the stabiliser end 2 is in the form of a circular ring-shaped weld seam 7, which is disposed at the outermost end of the stabiliser 2 and connects the stabiliser end 2 and the hollow shaft end 6 together.
This in the first place means that the entire length of the roll stabiliser 2 is uniformly available for the intended twisting deformation of the stabiliser 2. This enables the roll stabiliser 2 to be of optimal design in structural terms, whereby a linear response behaviour of the stabiliser 2 precisely with the intended torsional stiffness can be achieved, accompanied by the lowest possible stabiliser weight.
In the represented embodiment the mounting of the hollow shaft 6 and therefore also of the roll stabiliser 2 with respect to the bearing carrier 3 is in the form of a fixed/movable mounting, in which a needle bearing 8 on the left-hand side, related to the drawing, as a movable bearing, is combined with a fixed mounting 9 disposed on the right-hand side, related to the drawing. Here the fixed mounting is in the form of a sleeve joint 9, whereby misalignments and shaft deflections of the stabiliser 2, for example due to dynamic wheel forces, in particular can be easily accommodated.
In the represented embodiment the connection between the hollow shaft 6 and the chassis-side end of the wheel control arm 1 or the tension strut 1, formed by the wheel control arm, of the wheel suspension is effected by means of two ball-and-socket joints 10,11, as can be seen in particular from Figure 3. Here the ball heads of the two ball-and-socket joints 10,11 are connected to two fastening projections 12,13 which are formed on the hollow shaft 6 and lie opposite one another, while the joint
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housings of the two ball-and-socket joints are disposed in the fork-shaped chassis-side end of the wheel control arm or the tension strut 1, or are formed by the end of the actual tension strut 1.
This is also shown schematically in the representation according to Figure 2, in which a correspondingly fork-shaped chassis-side end of a tension strut 1 with the ball-and-socket joints 10, 11 disposed in the two fork ends can be seen by way of example.
As emerges from a combined view of Figures 1 and 3, the arrangement according to the invention of the straight stabiliser or stabiliser end 2, hollow shaft 6 and bearing carrier 3 permits in particular a separation of functions, disposed in a row in the axial direction of the stabiliser 2, between the various functions "stabiliser mounting", "introduction of force" from the wheel control arm 1 into the stabiliser 2 and "connection" of the stabiliser device to the chassis or axle carrier. This creates not only an extremely assembly-friendly stabiliser device structure which is robust in operation, but also saves a considerable amount of valuable construction space when compared with other solutions which are proposed in the prior art. In addition, the represented stabiliser device can be attached to the vehicle chassis in the simplest manner as a complete, pre-assembled unit, while at the same time the connection of the entire arrangement solely via the elastomer bearings 4, 5 results in an advantageous, tolerance-insensitive assembly process.
As a result, it therefore becomes clear that, due to the invention, a stabiliser device is created which, with respect to the prior art, provides considerable advantages regarding comfort properties and structure-borne sound isolation of the running gear while maintaining the direct stabiliser response. In this respect, when compared with the prior art, significant improvements are in addition achieved in relation to the construction space required and regarding the modularity in structure and assembly.
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The invention therefore provides a considerable contribution regarding the structural improvement and with regard to simplifications in the assembly of wheel-controlling stabiliser devices, in particular for use with axle systems of an exacting nature in terms of "vehicle movement dynamics.
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List of reference numbers

1 wheel control arm, tension strut
2 roll stabiliser
3 bearing carrier
4,5 bearing point, elastomer bearing
6 hollow shaft
7 weld seam
8 movable bearing, needle bearing
9 fixed bearing, sleeve joint
10,11 ball-and-socket joint
12,13 fastening projection
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WE CLAIM:
1. Stabiliser device for an axle of a motor vehicle/ the axle having a roll stabiliser (2) and at least one wheel control arm (1) for each wheel, wherein the chassis-side articulation of the wheel control arm (1) is connected to an end region of the roll stabiliser (2) such that twisting actuation of the roll stabiliser (2) takes place through a deflection movement of the wheel control arm (1), characterised in that the roll stabiliser (2) is in each case accommodated at the ends in a hollow shaft (6) which is connected to the wheel control arm (1) and is hollow at least in regions, wherein the hollow shaft (6) is mounted in a chassis-side bearing carrier (3) which can be resiliently connected to the vehicle.
2. Stabiliser device according to Claim 1, characterised in that the resilient connection of the bearing carrier (3) to the vehicle has an at least twice as high spring rate in the z direction (vertical axis of the vehicle) as in the x direction or y direction.
3. Stabiliser device according to Claim 1 or 2, characterised in that the bearing carrier (3) is resiliently connected to the vehicle by elastomer bearings (4, 5) or hydro bearings (4, 5).
4. Stabiliser device according to Claim 3, characterised in that the elastomer bearings (4, 5) or hydro bearings (4, 5)
are distributed centrosymmetrically in relation to the point of intersection of the longitudinal axes of the wheel control arm (1) and the hollow shaft (6).
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Stabiliser device according to any one of Claims 1 to 4, characterised in that the roll stabiliser (2) is essentially formed by a straight bar or by a straight tube.
Stabiliser device according to any one of Claims 1 to 5, characterised in that the roll stabiliser (2) consists of two separate stabiliser halves, wherein an actuator for relative twisting of the stabiliser halves with respect to one another can be disposed between the stabiliser halves.
Stabiliser device according to any one of Claims 1 to 6, characterised in that the wheel control arm (1) is connected to the hollow shaft (6) by means of two ball-and-socket joints (10,11).
Stabiliser device according to Claim 7, characterised in that the centre points of the balls of the ball-and-socket joints (10, 11) are disposed on a diametral straight line of the hollow shaft (6).
Stabiliser device according to Claim 7 or 8, characterised in that the joint housings of the ball-and-socket joints (10,11) are formed by the wheel control arm (1).
Stabiliser device according to any one of Claims 1 to 9, characterised in that the hollow shaft (6) is mounted in the bearing carrier (3) by means of a fixed/movable mounting (8, 9).
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11. Stabiliser device according to Claim 10, characterised in that the fixed bearing (9) of the hollow shaft is formed by a sleeve joint (9).
12. Stabiliser device according to any one of Claims 1 to 11, characterised in that the wheel control arm (1) is a tension strut or compression strut of a wheel suspension.
Dated this 4th day of August, 2008

HIRAL CHANDRAKANT JOSHI AGENT FOR ZF FRIEDRICHSHAFEN AG
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