Abstract:
The invention relates to a wheel suspension for a motor vehicle, comprising a wheel-side carrier part ( 12 ) holding a vehicle wheel ( 1 ) in a rotatable manner, and an axle-side guiding part ( 14 ) between which mutually rotating rotary parts ( 16, 18 ) are arranged. The guiding part ( 14 ), the rotary parts ( 16, 18 ) and/or the carrier part ( 12 ) interact with first and second effective areas ( 18   a,    36   a;    18   b,    16   b;    16   a,    54   a ) facing each other. According to the invention, the first effective area radially defines a conical or spherical hollow profile into which the corresponding second effective area protrudes in an essentially form-fitting manner.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2010/002427, filed Apr. 21, 2010, which designated the United States and has been published as International Publication No. WO 2010/130329 and which claims the priority of German Patent Application, Serial No. 10 2009 021 093.8, filed May 13, 2009, pursuant to 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The invention relates to a wheel suspension of a motor vehicle. 
     In so-called active steering systems, especially for the rear axle of vehicles, the wheel camber or the wheel toe can be adjusted via an actuator so that handling of the motor vehicle can be influenced by controlling the actuator. 
     DE 10 2004 049 296 A1 discloses a generic wheel suspension for a motor vehicle. It includes a hub unit which rotatably supports the vehicle wheel, and an axle-side guide part, with rotary parts being disposed between the hub unit and the guide part. The rotary part facing the hub unit is a cylindrical adjusting ring having cylindrical inner and outer effective areas which interact with corresponding effective areas of the other rotary part and the hub unit. The rotation axes of both rotary parts are aligned at a slant in relation to one another. When the two rotary parts are rotated, the wheel toe or the wheel camber can be adjusted. 
     Both rotary parts can be rotated in any relation to one another by servo drives. The desired toe-in/camber adjustment can be established in dependence on the combination of the rotation angles. In the extreme case, the resultant diffraction angle may be in the order of several angle degrees. This means that the carrier part can be positioned at a slant at an angle of several angle degrees in relation to the guide part which is mounted with further suspension arms to the vehicle body. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object to provide a wheel suspension which allows a reliable support of encountered radial forces and axial forces. 
     The object is solved by a wheel suspension for a motor vehicle, including a wheel-side carrier part rotatably supporting a vehicle wheel, and an axle-side wide part between which rotary parts are arranged and rotatable in relation to one another, with the guide part, the rotary parts and/or the carrier part interacting with facina first and second effective areas, wherein the facing effective areas between the guide part, the rotary part and/or the carrier part of the wheel suspension are not configured cylindrically but a first effective area may radially delimit a conical or spherical hollow profile in which the second facing effective area is able to at least substantially engage formfittingly. 
     The inventive idea may conceivably include different variants of the two facing effective areas: For example, both facing effective areas may have conical configuration, or a first one of the effective areas may be configured as spherical cup whereas the second effective area may have a corresponding spherical configuration to engage this spherical cup. As an alternative, the first effective area can be conical whereas the second effective area is a surface in the shape of a spherical disk to thereby establish a conical socket/spherical disk bearing. 
     According to a preferred embodiment, the two rotary parts placed between guide part and carrier part may form an actuator for adjusting a toe angle and/or camber angle. The facing effective areas can hereby be dimensioned between the two rotary parts in such a way as to slantingly position the rotation axis of the one rotary part in relation to the rotation axis of the other rotary part by an inclination angle. 
     In accordance with a variant, the facing effective areas can contact one another directly or through intervention of a friction-reducing coating so as to provide overall a cost-efficient and durable slide bearing between both effective areas. 
     As an alternative, the facing effective areas can be connected to one another via a roller bearing. This may be a tapered roller bearing when the effective areas have a conical configuration. 
     According to the invention, three bearing points are established between the four-part wheel carrier comprised of carrier part, the two rotary parts and the guide part. In order to reliably absorb axial and radial forces, it is of advantage to configure each of the bearing points with tapered roller bearings. 
     As described above, the second rotary part has an effective area which faces the first rotary part and an effective area which faces the guide part. For a particularly compact construction that is stable in axial direction, these two effective areas may be expanded in opposite directions to one another on the second rotary part. 
     As described above, the first rotary part has in contrast thereto an effective area which faces the carrier part and an effective area which faces the second rotary part, with both effective areas being expanded in a same direction in a conical or spherical manner. 
     In light of this background, the second rotary part may include in axial direction on both sides a conical or spherical hollow profile, respectively, for engagement of the first rotary part on one hand and also the guide part on the other hand. The carrier part can be further arranged with its effective area radially inwards of the first rotary part for better use of installation space. 
     The wheel-side carrier part and the axle-side guide part can be fixed by a restraining means. In particular, the restraining means can apply a biasing force to maintain the guide and carrier parts under tension in the axial direction. As a result of such a securement or bracing of the carrier and guide parts, the bearing points can be exposed to loads, in particular axial compressive forces and radial forces, while axial pulling forces may be absorbed by the restraining means itself. 
     With regard to assembly, it is beneficial to interconnect the four parts of the wheel carrier, comprised of carrier part, the rotary parts and the guide part, in an assembly direction roughly by a plug-in connection, without the need for an undercutting construction to axially fix the parts. The assembly may be implemented by simply plugging the parts together. For structural reasons, it is furthermore preferred when the restraining means connects the guide part and the carrier part with one another, wherein the restraining means can be arranged radially outside the rotary parts. 
     The restraining means may at the same time act as a coupling between the carrier part and the guide part. The coupling can again transmit as a torque bridge a torque, such as a braking torque, from the carrier part onto the guide part and thus to the vehicle body. The restraining means may hereby be configured preferably as cardan joint or metal bellows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention will now be described with reference to several exemplified embodiments. 
       It is shown in: 
         FIG. 1  a basic representation of the device for adjusting toe and camber angles of a wheel suspension for motor vehicles with a multi-part wheel carrier; 
         FIG. 2  a concrete implementation of the device according to  FIG. 1 , having a carrier part which carries a wheel, a guide part which is articulated on wheel guide elements of the wheel suspension, and two pivotable rotary parts which can be adjusted by electric servomotors; 
         FIG. 3  the device according to  FIG. 2  by way of an enlarged illustration of the arrangement and pivotal support of the rotary parts and the carrier and guide parts; 
         FIG. 4  a greatly simplified view of the device for illustration of the adjustment mechanism; and 
         FIGS. 5   a  to  5   c  various variants of the effective areas between the two rotary parts. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     For a theoretical explanation of the invention,  FIG. 1  shows a rough basic representation of a wheel carrier  10  of a wheel suspension for motor vehicles, which carrier is subdivided for adjustment of the camber and/or toe of the vehicle wheel as follows: 
     The wheel carrier  10  has a carrier part  12  in which the wheel and the brake element (brake disk, brake drum) of a service brake of the motor vehicle is rotatably supported. It should be noted that any functional parts of the wheel suspension that have not been described can be of conventional structure. 
     The wheel carrier  10  further includes a guide part  14  which interacts with the wheel suspension or optionally may form part of the wheel suspension. 
     Two substantially rotation-symmetrical rotary parts  16 ,  18  are provided as actuators between the carrier part  12  and the guide part  14  and are connected for rotation with the carrier part  12  and the guide part  14 , respectively, via respective rotation axes  20 ,  22 . Both rotation axes  20 ,  22  are oriented coaxially in the figures and extend in the wheel rotation axis. 
     Whereas the contact surfaces of the rotary parts  16 ,  18  directly adjacent to the carrier part  12  and the guide part  14  are configured rotation-symmetrically, the rotary parts  16 ,  18  bear upon one another via slanted surfaces  16   b ,  18   b  in such a way that the rotary part  16  pivots about a rotation axis  24  which is inclined upwards in  FIG. 1 . The rotation axis  24  is thus oriented, as shown, perpendicular to the slanted surfaces  16   b ,  18   b  and inclined at a defined angle x in relation to the rotation axis  22 . 
     In  FIG. 1 , the center axis  20  of the carrier part  12  is oriented in coaxial relation to the rotation axis  22  of the guide part  14  so that the vehicle wheel, held on the carrier part  12 , is set without camber and toe angles.  FIG. 4 , which is being described further below, indicates in addition also the center axis  20 ′. The shown angular disposition of the center axis  20 ′ is established as the rotary parts  16 ,  18  pivot about a rotation angle of 180°. 
     Provided on the carrier part  12  and the guide part  13  are electric servomotors  26 ,  28 , respectively, which are connected in driving relationship with the rotary parts  16 ,  18  in the basic representation via toothed belts  30 . The rotary parts  16 ,  18  can be rotated by the servomotors  26 ,  28  in same direction or in opposite direction in both rotational directions so that the carrier part  12  executes a pivoting motion or a wobbling motion in order to accordingly change the toe angle and/or the camber angle of the wheel. 
       FIGS. 2 and 3  show a longitudinal section of a concrete embodiment of the wheel carrier  10  along the rotation axis  22  of the wheel of the wheel suspension. 
     As described above, the wheel carrier  10  is comprised of the guide part  14  which is articulated to wheel guide elements such as suspension arms etc., the carrier part  12  which supports the wheel, and the rotation-symmetrical rotary parts  16 ,  18 . 
     The guide part  14  has a support flange  34  which supports a radially inwardly arranged bearing ring  36 . According to  FIG. 3 , the conical effective area  36   a  of the bearing ring  36  faces the conical effective area  18   a  of the radially outwardly arranged rotary part  18 . The bearing ring  36  forms via bearing rollers  38  with the radially outwardly arranged rotary part  18  a first tapered roller bearing which is defined by a rotation axis in coincidence with the rotation axis  22 . 
     The rotary part  18  has an outer circumference provided with a gear rim  18   c  which interacts in driving relationship with an invisible drive gear of the electric servomotor  28 . The servomotor  28  is also mounted to the support flange  34  of the guide part  14 . 
     According to  FIG. 3 , the carrier part  12  has a radially aligned flange portion  40  and an axially extending hub portion  42 . The hub portion  42  extends radially within the two rotary parts  16 ,  18  up to a level with the bearing ring  36  of the support flange  34 . 
     Provided within the flange portion  40  is a wheel bearing  44  as pivot bearing for a wheel flange  46  which has a hub portion  48  which projects likewise axially to the hub portion  42  also roughly up to the bearing ring  36 . 
     The wheel or the wheel rim  32  and the brake disk  52  of a disk brake are fastened to the wheel flange  46  by wheel bolts  50  (shown also partially). The caliper of the disk brake is fastened to the flange portion  40  of the carrier part  12  in a manner which is not apparent. 
     Furthermore, the rotary part  16  is rotatably supported on the hub portion  42  via an inner bearing ring  54  and a tapered roller bearing  56 , with the rotation axis of the hub portion also coinciding with the wheel rotation axis  22 . The inner bearing ring  54  and the radially outer rotary part  16  have facing conical effective areas  54   a  and  16   a  between which the tapered roller bearing  56  is provided. 
     The rotary part  16  is further rotatably supported in the rotary part  18  via a third tapered roller bearing  58  with bearing rollers. The relevant conical effective areas  16   b ,  18   b  are hereby slantingly configured in relation to the rotation axis  22  so that a rotation causes adjustment of the camber angle and/or toe angle of the wheel from the neutral position in a range of about 5°. 
     According to  FIG. 3 , the rotary part  16  engages into an axial groove  40   a  of the flange portion  40  and supports an outer gear rim  16   c  which is connected in driving relationship with the servomotor  26  via a hidden drive gear and through a recess in the flange portion  40 . The servomotor  26  is respectively fastened to the flange portion  40  of the carrier part  12 . 
     The wheel flange  46  is operated via a cardan shaft  60 , shown only in part by way of its bell-shaped joint housing  62  and the sleeve-shaped driving journal  64  for the sake of simplicity. The driving journal  64  is inserted via a spline  64   a  into the hub portion  48  of the wheel flange  46  and tightened by a locking bolt  66  with a locking sleeve  68  against the wheel flange  46 . A distance sleeve  69  is supported between a ring shoulder of the bell-shaped joint housing  62  and the wheel bearing  44  and arranged in coaxial relationship to and in radial direction between the hub portions  42 ,  48  of the carrier part  12  and the wheel flange  46 . The locking bolt  66  thus braces the assembly comprised of locking sleeve  68 , wheel flange  46 , wheel bearing  44 , distance sleeve  69 , and cardan shaft  60 . 
     According to  FIGS. 2 and 3 , a cardan ring  72  is provided radially outside the rotary parts  16 ,  18  as restraint against rotation between the guide part  14  and the carrier part  12  and is guided on the flange portion  40  of the carrier part  12  in circumferential direction in a formfitting manner via, for example, axial catches which project into the cardan ring  72 . The cardan ring permits only angular deflections but no relative rotation. 
     The device for adjustment of the wheel camber and/or toe, as described above, is sealed radially to the outside against environmental impacts such as moisture and dirt by a rubber-elastic bellows  74  (cf.  FIG. 2 ). The bellows  74  is respectively fastened to ring-shaped projections  40   a ,  34   a  of the flange portion  40  of the carrier part  12  and the support flange  34  of the guide part  14 . 
     As an alternative, as shown in  FIG. 4 , the bellows  74  may be configured as thin-walled metallic bellows which is sufficiently torsionally rigid to provide restraint against rotation but yet is sufficiently flexible as to lastingly accommodate the mentioned adjustment angles while sealing the radially inwardly arranged functional parts. The described cardan ring  72  can then be omitted. 
     A radial inner sealing of the rotary parts  16 ,  18  and their roller bearings etc. is provided between the bearing ring  36  on the support plate  34  of the guide part  14  and the hub portion  42  of the carrier part  12  in the region of the bell-shaped joint housing  62  of the cardan shaft  60 . It should be noted in this context that the carrier part  12  executes a wobbling motion with a pivot center in the middle of the cardan joint at M ( FIG. 4 ) so that sufficient clearance should be provided at the annular gap between the bell-shaped joint housing  62  and the bearing ring  36 . 
     A sleeve-shaped sealing ring  76  is supported on the hub portion  42  for axial displacement to ensure reliable sealing and has on its end face a spherical portion  76   a  which interacts with a concavely shaped recess  36   b  in the bearing ring  36 . 
       FIG. 4  shows in a greatly simplified way the adjustment mechanism of the wheel suspension according to the invention. Therefore, the servomotors  26 ,  28  within the metal bellows  74  are operatively connected with the rotary parts  16 ,  18  which are indicated by the arrows. As already described with reference to  FIG. 3 , the rotary part  18  has two effective areas  18   a  and  18   b . The effective areas  18   a ,  18   b  are expanded conically in mutually opposite directions. 
     The effective areas  18   b  and  16   b  of both rotary parts  16 ,  18 , which areas are relevant for camber and toe adjustment are inclined upwards at a slant to the rotation axis  22  by a cone angle (y+x) and (y−x), respectively. The conical effective areas  54   a ,  16   a  between the bearing ring  54  and the rotary part  16  are hereby nested within one another in axial direction. 
       FIGS. 5   a  to  5   c  schematically show further variants of the invention. The arrangement shown in  FIG. 5   a  corresponds in its basic structure and mode of operation to the preceding devices. The difference to the preceding devices resides in  FIG. 5   a  in the provision between the rotary parts  16 ,  18  of a slide bearing in which the conical effective areas  16   b ,  18   b  are in direct contact. The rotary parts  16 ,  18  are moreover in rotating connection with the carrier part  12  and the guide part  14  via not shown radial and axial bearings. 
     In contrast to  FIG. 5   a , the slide bearings illustrated in  FIGS. 5   b  and  5   c  between the rotary parts  16 ,  18  are not realized using corresponding conical effective areas  16   b ,  18   b . Rather, the effective area  16   b  of the rotary part  16  is configured in  FIG. 5   b  roughly in the shape of a sphere and in sliding contact with an effective area  18   b  of the rotary part  18  of concave shape. In contrast thereto, the effective area  16   b  of the rotary part  16  in  FIG. 5   c  is configured as a surface in the shape of a spherical disk and projects into an effective area  18   b  configured as a surface in the shape of a conical socket.