Abstract:
A motor vehicle wheel suspension is stiff for transverse forces and elastic for longitudinal forces by defining a steering axle for steering movements between wheel and structure using the lower ball joint, the upper coupler bearing, and the upper ball joint.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is related to PCT International Application PCT/EP2013/001370, filed May 8, 2013, a national stage application of which is assigned U.S. Application Number ______. 
     
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    Exemplary embodiments of the present invention relate to a wheel suspension for a motor vehicle for the support of a wheel of the vehicle on the structure of the vehicle, as well as a motor vehicle equipped with at least one such wheel suspension. 
         [0003]    European patent document EP 1 870 263 B1 discloses a wheel suspension having a wheel carrier for the coupling to a vehicle wheel as well as a lower trapezoidal link having, on the inside, a rear guide bearing for the coupling to a vehicle structure and a front guide bearing for the coupling with the vehicle structure and which is coupled to the wheel carrier on the outside via a lower ball joint. Furthermore, the wheel suspension comprises an upper camber link which has, on the inside, an upper guide bearing for coupling to the vehicle structure and which is coupled to the wheel carrier on the outside via an upper ball joint. Furthermore, the known wheel suspension is equipped with a coupler link coupled to the trapezoidal link via a lower coupler bearing and to the wheel carrier via an upper coupler bearing. The known wheel suspension is provided for an unsteered rear wheel. Nevertheless, it is equipped with a tie rod coupled on the outside to the wheel carrier via a footstep bearing and is connected on the inside to an actuator, with the help of which a toe angle as well as a camber angle are able to be changed depending on the operational state of a vehicle equipped with the wheel suspension. Finally, the known wheel suspension is furthermore equipped with a damper, which is supported with a lower damper support on the upper camber link, and a spring, which is supported via a lower spring support on the trapezoidal link in the region of a connection line, which connects the front guide bearing to the lower ball joint. 
         [0004]    Exemplary embodiments of the present invention provide an improved embodiment for a wheel suspension of the type described above or for a related vehicle, which is distinguished in that it enables an unburdening of the coupler link. Furthermore, the wheel suspension can be comparatively stiff and precise in the vehicle transverse direction, while being comparatively elastic or flexible in the vehicle longitudinal direction. Furthermore, exemplary embodiments provide a high-quality noise damping. 
         [0005]    The present invention is based on the general thought of defining a steering axle for steering movements between wheel and structure with the lower ball joint and the upper ball joint and of arranging the upper coupler bearing in the region of this steering axle. Due to this configuration, the coupler link is continuously unburdened during statically stable driving states. 
         [0006]    The wheel suspension presented here can be designed particularly simply as a wheel suspension for a steerable vehicle wheel. In particular, the wheel suspension can be provided for a rear wheel. Furthermore, the wheel suspension can be an independent wheel suspension 
         [0007]    Advantageously, an inner connection line, which connects the rear guide bearing to the front guide bearing, extends, in particular for a wheel suspension conceived as a rear wheel suspension, frontwards, upwards, and outwards from the rear guide bearing to the front guide bearing. This is achieved, in an assembled state on the structure by a corresponding spatial arrangement of the rear guide bearing and of the front guide bearing. This spatial alignment of the inner connection lines defines a longitudinal pole for the respective vehicle wheel, around which the respective wheel is mounted to be able to swivel by means of the wheel suspension, and leads to an improved start-up support. In the ideal case, the longitudinal pole lies in the direction of a resulting reaction force arising during start-up and engaging with the respective wheel such that this reaction force is orientated substantially by the longitudinal pole and thus substantially cannot generate torque on the wheel such that the wheel substantially does not decompress during start up. A corresponding behavior is set in a driven wheel, also in a propulsion operation as well as in a load change, such that also a propulsion support as well as a load change support can be considerably improved. Finally, it is particularly interesting in the case that a recuperation operation is implemented via the driven wheel, preferably in connection to the electromotor, which can lead to comparatively strong load changes on the wheel. The improved support increases the driving comfort and stabilizes the driving behavior of the vehicle. 
         [0008]    In another advantageous embodiment, the rear guide bearing is situated behind a wheel pivot, while the front guide bearing is situated in front of the wheel pivot. Optionally, it can furthermore be provided that, in a projection characterized by a vertical projection direction and a horizontal projection plane, a rear connection line that connects the rear guide bearing to the lower ball joint is at an acute angle with the wheel pivot. Due to these measures, a transverse support of the vehicle wheel with regard to a pneumatic trail can be improved in such a way that the transverse support occurs extensively via the rear guide bearing, while the front guide bearing is unburdened extensively from these transverse forces. In the ideal case, a distance of the rear guide bearing from the wheel pivot is coordinated with the usual pneumatic trail. This embodiment of the wheel suspension leads, in particular, to a significant unburdening of the front guide bearing such that this can be conceived to be weaker, whereby the wheel suspension overall has a weaker or more elastic effect for the longitudinal forces. 
         [0009]    According to an advantageous embodiment, the wheel suspension can be equipped with a tie rod coupled to the wheel carrier on the outside via a footstep bearing, wherein the upper coupler bearing is arranged between the upper ball joint and the footstep bearing is arranged on the wheel carrier. The selected positioning leads to a comparably long coupler link that enables a stable support between wheel carrier and trapezoidal link. Thus, the stiffening of the wheel suspension can be improved with regard to transverse forces. 
         [0010]    According to another advantageous embodiment, a wheel bearing can be provided, with the help of which the respective vehicle wheel can be fixed to the wheel suspension. This wheel bearing is fixed to the wheel carrier. Furthermore, according to an advantageous development, a drive shaft can drive a wheel hub of the wheel bearing. Thus, the wheel suspension presented here can be used for a driven wheel. The drive shaft can therein be connected in a usual manner to a drive train of the vehicle. Likewise, it is possible to couple the drive shaft to an electromotor allocated to the respective vehicle wheel. 
         [0011]    Provided that the driven wheel is furthermore a steerable wheel, the drive shaft can expediently have a drive joint. Particularly advantageous now is an embodiment in which the drive joint lies in the region of the steering axle. Due to this measure, forces occurring during steering and/or during compressing and decompressing of the wheel carrier in the drive joint can be reduced. Furthermore, due to this measure, slide paths occurring on a further, inner bearing during steering, via which the respective drive shaft is connected to be driven to the drive train or to the respective electro motor can be reduced. 
         [0012]    In another advantageous embodiment, the camber link can lie in the region of a horizontal wheel central plane in which a wheel pivot lies. Hereby the lever available for the transfer of steering forces is particularly large, whereby the forces to be applied via the tie rod can be reduced accordingly and in particular the tie rod can be dimensioned to be lighter. 
         [0013]    According to another advantageous embodiment, a damper can be provided that is supported via a lower damper support on the trapeze bearing and which is able to be supported via an upper damper support or on the structure. The lower damper support is preferably arranged in the region of a lower connection line connecting the lower guide bearing to the lower ball joint. In this way, damping forces have an effect substantially only in the region of this lower connection line, whereby toques are avoided or reduced on the lower guide bearing. In this way, in particular the front guide bearing can be conceived as an elastomer bearing designed to be particularly weak. 
         [0014]    According to another advantageous embodiment, a spring can be provided that is supported via a lower spring support on the trapezoidal link and which can be supported via an upper support or on the vehicle structure. Expediently, the lower spring support can now lie in the region of a lower connection line connecting the lower guide bearing to the lower ball joint. Thus, spring forces have an effect fundamentally only on this lower connection line, which means an unburdening of the front guide bearing, whereby this for example, can be conceived to be particularly weak. 
         [0015]    A combination of both embodiments named above is particularly advantageous such that both the damper and the spring lie in the region of the rear connection line over their respective lower support. Therein, damper and spring can be arranged separately and eccentrically to each other such that the lower damper support and the lower spring support are not arranged coaxially but next to each other and at a distance to each other. As far as the damper and spring are implemented separately, it can be preferred to arrange the lower spring support further inside, so proximally to the lower guide bearing, while the lower damper support is then arranged expediently proximally to the lower ball joint. Alternatively, a coaxial arrangement of damper and spring is fundamentally conceivable, for example in the form of a combined damper and spring strut. 
         [0016]    According to another advantageous embodiment, an inner connection line connecting the rear guide bearing to the front guide bearing can run, in a projection having a vertical projection direction and a horizontal projection plane, substantially in parallel to an outer connection line connecting the lower coupler bearing to the lower ball joint. Due to the parallel direction of these connection lines, the guiding of the wheel carrier can be improved during compression and decompression, which affects the angled suspension advantageously and also improves the directional stability of the related wheel during compression and decompression. The formulation “substantially” therein does not exclude an angle between the inner connection lines and the outer connection lines in the projection plane, wherein this angle, however, is not greater than 20°, is preferably not greater than 15°, is preferably not greater than 10°, is preferably not greater than 5°. 
         [0017]    According to a particularly advantageous embodiment, a front connection line, which connects the front guide bearing to the lower ball joint, can run substantially perpendicularly to the inner connection lines in the projection mentioned above. Due to this measure, a direct force support can be implemented on the front guide bearing. Furthermore, a compact construction is supported by this geometry. Also, the formulation “substantially” does not exclude deviations from a right angle between the front connection lines and the inner connection lines in said horizontal projection plane. These deviations are, however, smaller than 20°, preferably smaller than 15°, preferably smaller than 10°, preferably smaller than 5°. 
         [0018]    According to another advantageous embodiment, the wheel suspension can be equipped with a stabilizer, which is coupled to the coupler link via a pendulum strut. Due to this measure, on the one hand a direct coupling is prevented between stabilizer and wheel carrier, whereby the freedom of design for the wheel carrier is considerably improved, which in particular considerably simplifies the design of the wheel suspension for a steerable wheel. On the other hand, the coupler link is coupled directly to the wheel carrier with regard to its movements such that an operative connection between the wheel carrier and the stabilizer that responds well or directly is also able to be achieved via the pendulum strut. In particular, the stabilizer can hereby be hinged within the wheel suspension comparably far on the outside, whereby the stabilizer works sensitively and can be designed overall to be lighter. 
         [0019]    According to another advantageous embodiment, the wheel suspension can include a steering stop having a first stop contour and a second stop contour, which abut onto each other on reaching the predetermined maximum steering angle between wheel and structure, wherein the first stop contour is formed on the wheel carrier while the second stop contour is formed on the coupler link. As the coupler link is adjusted analogically to the wheel carrier by its direct coupling with the wheel carrier, hardly any relative movements occur during steering and/or during compression or decompression between wheel carrier and coupler link, whereby the wear can be considerably reduced in the steering stop. Furthermore, the geometries of the stop contours can be designed considerably more simply as the coupler link and the wheel carrier are hardly moved relative to each other during compression and decompression. 
         [0020]    According to another advantageous embodiment, a wheel contact point and wheel pivot lie on the steering axle in a projection with a horizontal projection direction and a vertical projection plane. Hereby additional forces can be reduced in the wheel suspension during steering of the wheel. 
         [0021]    The vehicle according to the invention is characterized by a structure, by several wheels and by at least one wheel suspension of the type described above, with the help of which one of the wheels is supported on the structure. 
         [0022]    Further important features and advantages of the invention arise from the drawings and the corresponding description of the figures by means of the drawings. 
         [0023]    It is understood that the features that are named above and are still to be illustrated below are not only able to be used in the respectively specified combination, but also in other combinations or individually, without exceeding the scope of the present invention. 
         [0024]    Preferred exemplary embodiments of the invention are depicted in the drawings and illustrated in greater detail in the description below, wherein the same reference numerals refer to the same or similar or functionally identical components. 
         [0025]    In the general description above and in the description of the figures below, the used relative terms “lower”, “upper”, “rear”, “front”, “inner” and “outer” are to be understood in the view of the installed state of the wheel suspension on the vehicle. Thus “lower” is facing a subsurface on which the wheel of the vehicle stands. Accordingly “upper” is facing away from the subsurface. The term “rear” means in the direction of the vehicle rear. The term “front” means in the direction of the vehicle front. The term “inner” points transversely to the vehicle longitudinal direction to the center of the vehicle. The term “outer” points transversely to the vehicle longitudinal direction away from the vehicle center. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0026]    Herein are shown, schematically respectively, 
           [0027]      FIG. 1  a view of a wheel suspension from behind in a longitudinal direction (X axis) of a thus equipped vehicle, 
           [0028]      FIG. 2  a view in a vertical direction (Z axis) from above onto the wheel suspension, 
           [0029]      FIG. 3  a view from the outside in a transverse direction (Y axis) of the thus equipped vehicle. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    According to  FIGS. 1 to 3 , a wheel suspension  1 , which serves, in the case of a motor vehicle (not illustrated), to support a wheel of the vehicle (not illustrated) on a structure of the vehicle (not illustrated), comprises a wheel carrier  2 , a lower trapezoidal link  3 , an upper camber link  4 , a coupler link  5 , a tie rod  6 , a stabilizer  7 , a drive shaft  8 , a damper  9  and a spring  10 . Here, the wheel suspension  1  is preferably conceived as an individual wheel suspension for a steerable and driveable rear wheel of a motor vehicle, preferably of a passenger motor vehicle. 
         [0031]    For improved orientation, in  FIGS. 1 to 3  for an installed state of the wheel suspension  1 , in the vehicle, a vehicle longitudinal direction X, a vehicle transverse direction Y, and a vehicle vertical axis Z are indicated by double arrows. The X axis and the Y axis span a horizontal X-Y plane. The X axis and the Z axis span a vertical X-Z plane. The Y axis and the Z axis span a further vertical Y-Z plane. 
         [0032]    The wheel carrier  2  serves for the coupling to the wheel. For this purpose, a wheel bearing  11  is fixed on the wheel carrier  2 , which mounts a wheel hub  12  rotatably around a wheel pivot  13 . For improved understanding, the wheel carrier  2  in  FIG. 3  is depicted transparently and with a dashed line. 
         [0033]    The trapezoidal link  3  has, on the inside, a rear guide bearing  14  as well as a front guide bearing  15 , via which the trapezoidal link  3  can be coupled respectively to the vehicle structure. On the outside, the trapezoidal link  3  is coupled to the wheel carrier  2  via a lower ball joint  16 . 
         [0034]    The camber link  4  is able to be connected to the structure on the inside with the help of an upper guide bearing  17 . On the outside, the camber link  4  is coupled to the wheel carrier  2  via an upper ball joint  18 . 
         [0035]    The coupler link  5  is coupled to the trapezoidal link  3  via a lower coupler bearing  19  and to the wheel bearing  2  via an upper coupler bearing  20 . 
         [0036]    The lower ball joint  16 , the upper coupler bearing  20  and the upper ball joint  18  define a steering axle  21  for steering movements between the wheel and the structure. The steered wheel can thus swivel around this steering axle  21  relative to the structure. 
         [0037]    The tie rod  6  is coupled on the outside to the wheel carrier  2  via a footstep bearing  22 . Therein the footstep bearing  22  is expediently arranged behind the wheel carrier  2 , such that the tie rod  6  is introduced here from behind the wheel suspension  1 . The tie rod  6  is coupled on the inside expediently to a steering device (not illustrated), with the help of which steering movements can be introduced into the wheel carrier  2 . The upper coupler bearing  20  is now arranged between the upper ball joint  18  and the footstep bearing  22  on the wheel carrier  2 . The footstep bearing  22  is arranged in a region of a horizontal wheel central plane  23 , in which the wheel pivot  13  lies. 
         [0038]    The drive shaft  8  is connected to be driven to the wheel hub  12  of the wheel bearing  11 , whereby the vehicle wheel fixed on the wheel bearing  11  can be driven. While the drive shaft  8  is connected to be driven on the outside to the wheel hub  12 , the drive shaft  8  can be connected on the inside to a drive train of the vehicle (not illustrated). Alternatively, an embodiment is also conceivable in which a separate electromotor is allocated the respective wheel of the respective wheel suspension  1 , the electromotor driving the wheel hub  12  via the drive shaft  8  and thus the related wheel. It is clear that the drive shaft  8  can then have a different appearance than in the figures shown here. The drive shaft  8  has a drive joint  24  which, in the views shown here, is enclosed by a cuff  25  and is thus covered. The drive joint  24  is, however, arranged in the region of the steering axle  21 , so in particular lies on this steering axle  21 . 
         [0039]    The damper  9  is supported on the trapezoidal link  3  via a lower damper support  26 . The damper  9  can be supported, for example, on the structure via an upper damper support  27 . The lower damper support  26  is arranged in the region of a rear connection line  28 . The rear connection line  28  connects the rear guide bearing  14  to the lower ball joint  16 . The rear connection line  28  encloses an acute angle with the wheel pivot  13  of approximately  15 ° which can also be moved in an angle range of  5 ° to  30 ° . In any case, the rear guide bearing  14  is thus situated behind the wheel pivot  13  and indeed preferably approximately in the region of a pneumatic trail which concentrates the transverse support of the wheel suspension  1  on the rear guide bearing  14  and thus unburdens the front guide bearing  15  accordingly. 
         [0040]    The spring  10  is supported via a lower spring support  29  on the trapezoidal link  3  and can be supported, for example, on the vehicle structure via an upper support  30 . The lower spring support  29  likewise lies in the region of the rear connection lines  28 . 
         [0041]    In the case of the embodiments shown here, the damper  9  and the spring  10  are conceived as separate components and are arranged eccentrically to each other. According to this, the lower damper support  26  and the lower spring support  29  are arranged next to each other and at a distance to each other on the trapezoidal link  3  in the region of the rear connection lines  28 . Therein, the spring  10  is arranged further inside than the damper  9 . In particular, the spring  10  is supported on the trapezoidal link  3  approximately centrally between rear guide bearing  14  and lower ball joint  16 . 
         [0042]    The top view according to  FIG. 2  represents a projection having a vertical project direction (Z axis) and a horizontal projection plane (X-Y plane). In this projection or in this projection plane, an inner connection line  31  and an outer connection line  32  run substantially parallel to each other. In particular, their orientations deviate from each other by less than 5°. The inner connection line  31  connects the rear guide bearing  14  to the front guide bearing  15 . The outer connection line  32  connects the lower coupler bearing  19  to the lower ball joint  16 . In this projection of  FIG. 2 , a front connection line  33  stands substantially perpendicularly on the inner connection lines  31  and thus likewise substantially perpendicularly on the outer connection lines  32 . Here, deviations from the right angle are also expediently smaller than 5°. The front connection line  33  connects the front guide bearing  15  to the lower ball joint  16 . In  FIG. 2 , furthermore a further connection line  34  is depicted which connects the front guide bearing  14  to the lower coupler bearing  19 . In the projection of  FIG. 2 , this further connection line  34 , the inner connection line  31 , the front connection line  33  and the outer connection line  32  define a trapeze, that gives it name to the trapezoidal link  3 . In the shown particular case, this trapeze has two mostly right angles. 
         [0043]    The side view according to  FIG. 3  represents a projection having a horizontal projection direction (Y axis) and a vertical projection plane (X-Z plane). In this projection or in this projection plane, the wheel pivot  13  lies on the steering axle  21 . Furthermore, a wheel contact point not shown here, via which the respective wheel contacts a subsurface or a road, likewise lies on the steering axle  21 . Furthermore, the steering axle  21  extends in this projection mostly in parallel to the Z axis. In other words, the steering axle  21  lies in the Y-Z plane. 
         [0044]    According to  FIG. 1 , the steering axle  21  can have an incline, which can lie in a range, for example, from 5° to 30°, compared to the vertical direction (Z axis). 
         [0045]    The stabilizer  7  is coupled to the coupler link  5  inside of the wheel suspension  1  via a pendulum strut  35 . Therein the pendulum strut  35  is coupled to the coupler link  5  via a lower pendulum bearing  36 . The lower pendulum bearing  36  is therein arranged on the coupler link  5  between the lower coupler bearing  19  and the upper coupler bearing  20 . Furthermore, the lower pendulum bearing  36  lies on a connection line  37  connecting the lower coupler bearing  19  to the upper coupler bearing  20 . The pendulum strut  35  is furthermore coupled to the stabilizer  7  via an upper pendulum bearing  38 . This upper pendulum bearing  38  is arranged approximately in the height region of the upper coupler bearing  20  with regard to the Z axis. 
         [0046]    The vehicle suspension  1  is furthermore equipped with a steering stop  39  having a first stop contour  40  and a second stop contour  41 . The two stop contours  40 ,  41  come to rest on each other on achieving a predetermined, maximum steering angle between the wheel and the structure. The first stop contour  40  is formed here on the wheel carrier  2  and indeed expediently in the region of the upper coupler bearing  20 . The second stop contour  41  is formed on the coupler link  5  and indeed likewise in the region of the upper coupler bearing  20 . In the embodiment shown here, the two stop contours  40 ,  41  are formed integrally on the wheel carrier  2  or integrally on the coupler link  5 . Alternatively, an embodiment is also conceivably in which the first stop contour  40  is formed by a separate stop body that is attached to the wheel carrier  2 . Additionally or alternatively, the second stop contour  41  can be formed by a separate stop body, which is attached to the coupler link  5 . Expediently, the stop contours  40 ,  41  are designed for surface contact, whereby force peaks can be reduced on achieving the maximum steering angle. 
         [0047]    The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.