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 WHEEL SUSPENSION


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 : -


The invention relates to a wheel suspension according to the preamble of Claim 1.
The wheel suspension is a construction unit which is decisive for the fulfilment of the safety and comfort requirements. Therefore interfering influences which act on the wheel suspension must be compensated in the best possible way. For example, the inclination of a vehicle wheel relative to the road surface changes due to lateral force influences on the vehicle wheels, as arise when driving round a bend, or the rolling of the vehicle body. The camber which thus occurs at the vehicle wheel leads to a change in the tyre contact area, so that the vehicle wheel loses valuable grip on the undersurface.
Double wishbone axles known until now compensate for this tendency to camber by specifically influencing the wheel position by producing an opposed, negative camber which can be achieved through different lengths and/or orientations of the wishbones. However this leads to disadvantages while the motor vehicle is moving straight ahead, that is when individual vehicle wheels deflect on one side, as occurs when travelling over uneven ground, for example. Furthermore, undesirable tyre wear occurs and valuable lateral force potential of the tyre is lost in the case of double wishbone wheel suspensions of this kind.
EP 1 070 609 Bl describes a wheel suspension which is constructed as a double wishbone axle. The particular feature of this solution lies in the fact that a compensating means in the form of a steering rocker is used which establishes a flexible connection of the ends of an upper and a lower link which are on the vehicle body side. Here both link ends are disposed on a common steering rocker. The opposite ends, i.e. on the wheel side, of these wishbones are in each case fastened to a wheel carrier.
A further wheel suspension for a motor vehicle is known from US 6,929,271 B2. This wheel suspension has stabilisers as compensating means for the correction of wheel positions, such as, for example, the wheel camber, in which case both a connection of
2
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two mutually opposite wheels, i.e. the wheels of both vehicle sides, and a coupling of front to rear wheels are provided. In this solution double-acting piston-cylinder units, which are integrated into the stabiliser of the motor vehicle, are used as compensating means, which units, for example, compensate for undesirable wheel movements when driving round a bend. The wheel suspension which is known from US 6,929,271 Bl has a wishbone which is flexibly coupled to a wheel carrier bearing a vehicle wheel.
A feature which is common to these known solutions is that the forces acting on the vehicle wheels and the resultant displacements of the vehicle wheels are compensated by coupling a plurality of vehicle wheels together, with compensating means which are adapted for this being used.
DE 10 2006 006 513 Al also discloses a wheel suspension for a motor vehicle in which at least one first and at least one second link are in each case flexibly connected to a wheel carrier bearing a vehicle wheel. The wheel suspension comprises compensating means for correcting wheel positions, each of the links comprising a compensating means or being connected to a compensating means and the compensating means of a vehicle wheel in each case being connected to one another by at least one coupling member. This solution provides a force-regulated, passive camber adjustment of the vehicle wheels. Here the tracking behaviour of the vehicle wheel under the influence of a lateral force can also be passively regulated, depending on the design of the construction.
In addition, US 2005/0236797 Al discloses a wheel suspension with a wheel carrier bearing a vehicle wheel and constructed in two parts, with a first part of the wheel carrier being flexibly connected to a second part of the wheel carrier. Compensating means of a complex form are provided to connect the first part of the wheel carrier to the second part of the wheel carrier.
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The object of the invention is to provide a wheel suspension for a motor vehicle with which a camber and/or track adjustment of the individual vehicle wheels is possible with simple means.
The invention achieves this object with the features of Claim 1. Further configurations of the invention are reproduced in the subsequent subclaims.
A wheel suspension with a wheel carrier bearing a vehicle wheel and formed in two parts, in which a first part of the wheel carrier is flexibly connected to a second part of the wheel carrier, has been further developed so as to use compensating means to connect the first part of the wheel carrier to the second part of the wheel carrier.
In this respect compensating means are understood to be components parts or sub¬assemblies which compensate for or transmit movements.
In a certain sense, with regard to the solution, it is possible to speak of a "force-regulated" or, better: "force-controlled" construction, which means that a lateral force acting on the vehicle wheel changes the camber and/or the track of the vehicle wheel and, according to the invention, this change is followed by an opposed compensation of camber and/or track.
A solution of this kind now also enables the principle of a passive camber and track adjustment to be applied not just to a limited number of wheel suspensions, but to use this for all wheel suspensions known until now, in which case the term "passive" is to be understood to the effect that no "active" elements which influence the camber or the track of the vehicle wheel by supplying external energy are used here. In this connection the passive camber adjustment is integrated into the actual wheel carrier. According to the invention, this consists of two parts. By dividing the wheel carrier into two individual components, the wheel carrier parts can be moved relative to one another. Track and camber corrections can therefore be realised in the best possible way. A significant increase in the safety of a motor vehicle can be
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achieved with the invention. The wheel carrier according to the solution which is presented here can be used both for steered and for unsteered wheel suspensions.
Through this arrangement it is also possible to produce an additional negative camber of the vehicle wheel in relation to the vehicle body which significantly increases the lateral force potential of the tyre. In other words, the grip between the roadway and the tyre is improved when taking a corner. The invention thus allows the required movements of the components only to take place in the "wheel carrier system", which is why it can be used in different axle systems. Apart from the increased lateral force potential, a reduction of the tyre wear can also advantageously be achieved.
Rotatable links can be used as compensating means, in which case, according to one configuration of the invention, a rotatable link can be understood to be, for example, triangular links which comprise at least three joints. By connecting the two wheel carrier parts via the above-mentioned compensating means, these are indirectly coupled together. The triangular links have in particular proved successful as compensating means, as they have three joint points. As a result, not only can an indirect coupling of the two wheel carrier parts be achieved, but a further joint point is also available at each of the triangular links, by means of which joint point the triangular links are coupled together according to the invention by a coupling member which is adapted for this purpose.
Furthermore, according to one development of the invention, it is proposed that the joints can be ball-and-socket joints, pivot joints or elastomer bearings. In this respect elastomer bearings are understood to be joints with at least one elastomer layer. Elastomer bearings of this kind have the advantage that, depending on the structure, they can produce a certain restoring moment which is based on the elastic properties of the elastomer material. In the simplest case the elastomer bearings can be hinge joints with damping properties.
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Different dimensioning of the rotatable links lies within the scope of the invention. In this respect the dimensioning of the rotatable links can be selected so that a lateral force occurring at the wheel contact point initially gives rise to a movement of the lower point of rotation of the first part, i.e. on the wheel side, of the wheel carrier in the direction of the lateral force. This movement is transmitted via the rotatable links and at least one coupling member to the upper point of rotation of the wheel carrier. A greater movement of the upper point of rotation in the direction of the lateral force then occurs to produce a negative camber.
A first preferred geometric design of the rotatable links can be seen, for example, in that on the side of a vehicle wheel the distance between the upper fastening point, related to the motor vehicle, on the vehicle wheel side and the lower fastening point of an upper rotatable link is greater than the distance between the upper fastening points on the vehicle wheel side and the associated lower fastening points of the other, lower rotatable links.
The ratio of the distance of the upper fastening point, related to the motor vehicle, on the vehicle wheel side of an upper rotatable link to the distance of the upper fastening point on the vehicle body side of the same upper rotatable link can equally be greater than the ratio of the distance of the upper fastening points on the vehicle wheel side to the distance of the upper fastening points on the vehicle body side of the other, lower rotatable links.
Design variants of this kind can of course also be used in combination with one another.
The invention is illustrated in detail in the following on the basis of the accompanying drawings. The embodiments which are shown do not represent a restriction to the represented variants, but serve solely to illustrate several principles of wheel suspensions according to the invention. Here components which are identical or of the same type are marked with the same reference numbers. In order
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to be able to illustrate the mode of operation according to the invention, the figures only show highly simplified basic representations in which component parts which are not essential for the invention have been omitted. However this does not mean that components of this kind are not found in a wheel suspension according to the invention.
In the drawings:
Figure 1: shows a simplified basic representation of a first constructional variant of the solution according to the invention on the basis of a non-deflected vehicle wheel,
Figure 2: shows the wheel suspension according to Figure 1 with a deflected vehicle wheel,
Figure 3: shows a simplified basic representation of a second variant of a wheel suspension according to the invention on the basis of a non-deflected vehicle wheel,
Figure 4: shows the representation according to Figure 3 with a deflected vehicle
wheel and
Figure 5: shows a simplified basic representation of a third embodiment of a wheel suspension according to the invention with a view of this wheel suspension partly in three dimensions.
The first variant which is shown in Figures 1 and 2 of a solution according to the invention comprises a vehicle wheel 1 which is rotatably fastened to a wheel carrier marked as a whole by 2. The difference between the representations in Figures 1 and
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2 consists solely in the fact that a non-deflected vehicle wheel 1 is represented in Figure 1 and a deflected vehicle wheel 1 is represented in Figure 2.
The wheel carrier 2 consists of a first part 3 and a second part 4 which is connected to the latter. The connection between the parts 3 and 4 of the wheel carrier 2 is established via two rotatable links 5 and 6 which are constructed as triangular links. The triangular links 5 and 6 in each case comprise three joint points 5a, 5b, 5c and 6a, 6b and 6c, respectively. At least one of the above-mentioned joint points 5a, 5b, 5c and 6a, 6b and 6c, respectively, comprises an elastomer bearing or consists overall of an elastomer bearing of this kind.
The first part 3 of the wheel carrier 2 is connected via a respective joint 5b, 6b to the triangular links 5 and 6. On the other hand, the second part 4 of the wheel carrier 2 is connected to the triangular links 5 and 6 via the joint points 5a and 6a. The triangular links 5 and 6 are also connected together via the joint points 5c and 6c and by a coupling member 11 which is constructed as a pendulum support. The triangular links 5 and 6 execute a movement in the same direction through the pendulum support 11.
The represented wheel suspension for a motor vehicle can be used both for a steerable vehicle wheel and for an unsteerable vehicle wheel. In the case of a steerable vehicle wheel the steering system would be mounted on the second part 4 of the wheel carrier 2.
As can be seen from the representations in Figures 1 and 2, the triangular links 5 and 6 have different geometries. Due to this different geometric design of the triangular links 5 and 6, the sequence of movements between the parts 3 and 4, which can move relative to one another, of the wheel carrier 2 can be specifically controlled. Thus the wheel suspension which is represented in Figures 1 and 2 can be used for a force-regulated or force-controlled, mechanical, passive camber adjustment.
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Links 9 and 10 serve to connect the wheel carrier 2 and therefore to connect the vehicle wheel 1 to the vehicle body 8. These links 9 and 10, which in the present case are formed as wishbones, are connected to the joint points 5a and 6a, respectively. If the vehicle wheel 1 is deflected, for example in consequence of a lateral force Fs acting on this, as is represented in Figure 2, the lower triangular link 6 is pivoted in the direction of the arrow A in Figure 2. In this case the rotational movement of the triangular link 6 takes place about the joint point 6b. This movement is transmitted according to the arrow A in Figure 2 through the coupling member 11 constructed as a pendulum support to the upper triangular link 5, so that this is also forcibly pivoted about the joint point 5b in the direction of the arrow A. As can clearly be seen from the representation in Figure 2, the parts 3 and 4 of the wheel carrier 2 have different angular positions in space when the vehicle wheel 1 is in a deflected position. This provides the desired additional negative camber when taking a corner. The vehicle safety is also increased by the accompanying increased grip between the tyres and the roadway.
The parts 3 and 4 of the wheel carrier 2 are coupled together by a spring 13 in order to produce a restoring force. Here the spring 13 only symbolically represents an element which makes this restoring force possible. It is equally possible to use equivalent means such as spriivg-damper units or other components here.
A further constructional variant of the invention is represented in Figures 3 and 4. The vehicle wheel 1 is held by a wheel carrier 2 in this case as well. As before, this wheel carrier 2 consist of two parts 3 and 4. The first part 3 of the wheel carrier 2 is connected to a triangular link 5 and 6, respectively, at the joint points 5b and 6b. The joint points 5a and 6a of the triangular links 5 and 6 represent a fastening for the second part 4 of the wheel carrier 2 and the links 9 and 10. The links 9, 10 are constructed as wishbones.
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This variant of a wheel suspension according to the invention also has a pendulum support 11 as the coupling member which connects the joint points 5c and 6c of the triangular links 5 and 6.
A McPherson wheel suspension with a spring-damper unit 12 for a non-deflected vehicle wheel is represented in Figure 3. Unlike Figure 3, Figure 4 shows the otherwise identical wheel suspension from Figure 3 for a deflected vehicle wheel. Here a lateral force Fs acts on the vehicle wheel 1, so that this is deflected. The vehicle wheel 1 inclines through a certain angle, which results in the lower triangular link 6 being pivoted about the joint 6b in the direction of the arrow B in Figure 4. Due to the triangular links 5 and 6 being coupled via the pendulum support 11, the movement which is introduced to the triangular link 6 is transmitted directly to the upper triangular link 5 located above. This likewise pivots about the joint point 5b in the direction of the arrow B in Figure 4.
Figure 5 shows another variant of a wheel suspension according to the invention which is presented here. A wheel suspension of this kind enables both the camber and the track to be passively adjusted. The adjustment takes place mechanically and in a force-regulated or force-controlled manner. An additional triangular link 7 is provided for this purpose.
As already explained in connection with the representations in Figures 1 and 2, this wheel suspension also comprises an upper triangular link 5 and a lower triangular link 6.
Two wishbones 9 and 10 connect the triangular link 5 and 6, respectively, from the joint points 5a and 6a, respectively, to the vehicle body 8. The first part 3 of the wheel carrier 2 is coupled to the respective associated triangular link 5 and 6 at the joint points 5b and 6b. The second part 4 of the wheel carrier 2 is fastened at the joint points 5a and 6a of the triangular links 5 and 6. There is a coupling connection consisting of a pendulum support 11 between the triangular links 5 and 6. This acts
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on the joint points 5c and 6c of the triangular links 5 and 6. In this respect the embodiment which is shown in Figure 5 is identical with the variant of Figures 1 and 2. The difference consists in the triangular link 7 which is additionally present and which likewise comprises three joint points 7a, 7b and 7c. This is disposed laterally-next to and in a different vertical position from the lower triangular link 6 and the upper triangular link 5. Here there is a coupling to the second part 4 of the wheel carrier 2 at the joint point 7a. The third triangular link 7 is connected to the first part 3 of the wheel carrier 2 at the joint point 7b. The joint 7c serves to fasten a coupling member 14, which also consists of a pendulum support in this wheel suspension, the opposite end of which support acts on the joint point 6c of the lower triangular link 6. The result of coupling the triangular link 6 to the triangular link 5 and the triangular link 7 via the respective pendulum support 11 and 14 is a synchronous movement of the triangular links 5 and 7, provided that the triangular link 6 is pivoted about the joint point 6b when the vehicle wheel 1 deflects. As already mentioned previously, at least one of the joints is constructed as an elastomer bearing or this comprises an elastomer bearing in this construction as well.

11

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List of reference characters
1 Vehicle wheel
2 Wheel carrier
3 First part of the wheel carrier
4 Second part of the wheel carrier
5 Compensating means (rotatable link)
6 Compensating means (rotatable link)
7 Compensating means (rotatable link)
8 Vehicle body
9 Link
10 Link
11 Coupling member (pendulum support)
12 Spring-damper unit
13 Spring
14 Coupling member (pendulum support)

12

1 4 MAY 2009.

CLAIM:
1. Wheel suspension with a wheel carrier (2) bearing a vehicle wheel (1) and
constructed in two parts, wherein a first part (3) of the wheel carrier (2) is
flexibly connected to a second part (4) of the wheel carrier (2),
characterised in that
compensating means (5, 6, 7) formed as rotatable links are provided to connect the first part (3) of the wheel carrier (2) to the second part (4) of the wheel carrier (2), wherein at least one coupling member in the form of a pendulum support (11, 14) forms a connection between two respective rotatable links (5 and 6, respectively 7 and 6).
2. Wheel suspension according to Claim 1,
characterised in that
the rotatable links (5, 6, 7) are triangular links which in each case comprise at least three joints (a, b, c).
3. Wheel suspension according to Claim 2,
characterised in that
the joints (a, b, c) are ball-and-socket joints, pivot joints or elastomer bearings.
4. Wheel suspension according to any one of Claims 1 to 3,
characterised in that
the pivot joints (5,6, 7) are of different dimensions.
5. Wheel suspension according to any one of Claims 1 to 4,
characterised in that
the distance between the upper fastening point (5a), related to the motor vehicle, on the vehicle wheel side and the lower fastening point (5b) of an upper rotatable link (5) is greater than the distance between the upper fastening points (6a, 7a) on the vehicle wheel side and the associated lower fastening points (6b, 7b) of the other, lower rotatable links (6,7).
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6. Wheel suspension according to any one of Claims 1 to 5,
characterised in that
the ratio of the distance of the upper fastening point (5a), related to the motor vehicle, on the vehicle wheel side of an upper rotatable link (5) to the distance of the upper fastening point (5c) on the vehicle body side of the same upper rotatable link (5) is greater than the ratio of the distance of the upper fastening points (6a, 7a) on the vehicle wheel side to the distance of the upper fastening points (6c, 7c) on the vehicle body side of the other, lower rotatable links (6,7).
7. Wheel suspension according to any one of the preceding Claims,
characterised in that
the parts (3, 4) of the wheel carrier (2) are coupled together by a spring (13) in order to produce a restoring force.
14 i1 4 MAY 2009
Dated this 11th day of May, 2009