Abstract:
A wheel suspension assembly for a vehicle is operable to travel across a ground surface. The wheel suspension assembly includes a first suspension member, a second suspension member, a wheel rotatably coupled to the first suspension member and a ball stud interconnecting the first and second suspension members. The ball stud includes a ball and a tapered shaft. The tapered shaft extends along a longitudinal axis. One of the first and second suspension members includes a ball socket in receipt of the ball. The other of the first and second suspension members includes a tapered bore in the receipt of the tapered shaft. The longitudinal axis of the tapered shaft is oriented substantially parallel to the ground surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation-in-part of U.S. patent application Ser. No. 11/029,960 filed on Jan. 5, 2005. The disclosure of the above application is incorporated herein by reference. 
     
    
     BACKGROUND AND SUMMARY OF THE INVENTION  
       [0002]     The present invention generally relates to a wheel suspension assembly for a vehicle and, more particularly, to a wheel suspension assembly having a horizontally aligned ball joint assembly.  
         [0003]     A wheel suspension assembly for a vehicle typically includes a knuckle or a spindle that rotatably supports one of the front and/or rear wheels of the vehicle. A tie rod, control arm or other suspension member may be rotatably coupled to the knuckle with a ball stud. The ball stud has a shank portion with a tapered external surface at one end and a substantially spherically shaped ball at the other end. Typically, the ball stud is vertically oriented relative to the ground. Because the stud is retained using a taper fit, it is difficult to accurately locate the center of the ball at a desired distance from the horizontally extending axis about which the wheels rotate.  
         [0004]     The positioning problem exists because the taper is typically a small angle. As such, even a small dimensional change in stud diameter or tapered hole size results in a relatively large variation in the position of the center of the ball stud relative to the wheel axis of rotation. Some independent rear suspensions require very accurately positioned ball joints to maintain the desired vehicle handling characteristics.  
         [0005]     One solution to the present issue would be to reduce the tolerances on the tapered surfaces of the knuckle and the ball stud to position the ball within a desired tolerance. However, the cost of manufacturing such assemblies may be prohibitive. Accordingly, it is desirable to manufacture a wheel suspension assembly having an accurately positioned ball in an economically feasible manner.  
         [0006]     The present invention relates to a wheel suspension assembly for a vehicle operable to travel across a ground surface. The wheel suspension assembly includes a first suspension member, a second suspension member, a wheel rotatably coupled to the first suspension member and a ball stud interconnecting the first and second suspension members. The ball stud includes a ball and a tapered shaft. The tapered shaft extends along a longitudinal axis. One of the first and second suspension members includes a ball socket in receipt of the ball. The other of the first and second suspension members includes a tapered bore in the receipt of the tapered shaft. The longitudinal axis of the tapered shaft is oriented substantially parallel to the ground surface.  
         [0007]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0009]      FIG. 1  is a fragmentary side view of a prior art wheel suspension assembly having a vertically oriented ball stud;  
         [0010]      FIG. 2  is a fragmentary side view of a wheel suspension assembly constructed according to the principles of the present invention;  
         [0011]      FIG. 3  is a fragmentary side view depicting an alternate embodiment wheel suspension assembly;  
         [0012]      FIG. 4  is a side view depicting an alternate embodiment knuckle and ball stud assembly;  
         [0013]      FIG. 5  is a fragmentary, cross-sectional view of an alternate embodiment wheel suspension assembly taken along line  5 - 5  shown in  FIG. 4 ;  
         [0014]      FIG. 6  is an end view of the knuckle and ball stud assembly shown in  FIG. 4 ;  
         [0015]      FIG. 7  is a top view of the knuckle and ball stud assembly shown in  FIG. 4 ;  
         [0016]      FIG. 8  is a fragmentary, cross-sectional view of an alternate embodiment wheel suspension assembly; and  
         [0017]      FIG. 9  is a fragmentary, cross-sectional view of an alternate embodiment wheel suspension assembly.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0019]      FIG. 1  depicts a portion of a prior art wheel suspension assembly  10  including a knuckle  12  and a control arm  14 . Knuckle  12  is rotatably coupled to control arm  14  with a ball stud  16  and a nut  18 . Ball stud  16  includes a tapered shank  20  and a ball  22 . Tapered shank  20  includes an external surface  24  engaged with a surface  26  of a tapered aperture  28  formed in knuckle  12 . Due to the relatively small angle of the taper, small dimensional variations in the size of tapered shank  20  and/or the size of tapered aperture  28  result in a multiplied variation in the position of a center  30  of ball  22  relative to a centerline  32  of a wheel  33 . Based on a standard taper of 4.8 degrees, a dimension  34  varies at a multiplied rate of 6 to 1. For example, a change in the size of tapered shank  20  of 0.010 inches results in a 0.060 inch variance in dimension  34 . As described above, a positional variance of this magnitude is unacceptable in certain suspension applications.  
         [0020]      FIG. 2  depicts a wheel suspension assembly  50  constructed in accordance with the teachings of the present invention. Wheel suspension assembly  50  includes a knuckle  52  and a control arm  54  rotatably interconnected by a ball stud  56 . Knuckle  52  is operable to rotatably support a wheel  57  for rotation about an axis  58 . Axis  58  extends substantially parallel to a ground surface  60  over which a vehicle equipped with wheel suspension assembly  50  may travel. Knuckle  52  includes a tapered aperture  62  having a tapered wall surface  64 .  
         [0021]     Ball stud  56  includes a substantially spherical ball  66  integrally formed with a tapered shank portion  68  and a threaded portion  70 . Threaded portion  70  is formed at an end opposite ball  66 . A nut  72  is in threaded engagement with threaded portion  70 . Nut  72  reacts against a face  74  of knuckle  52  to draw tapered shank portion  68  into engagement with tapered wall surface  64  of tapered aperture  62 . Ball stud  56  includes a longitudinal axis  76  about which tapered shank portion  68  is formed.  
         [0022]     Control arm  54  includes a socket  78  in receipt of ball  66 . Socket  78  is sized and shaped to retain ball  66  within socket  78  while allowing control arm  54  to rotate relative to knuckle  52 . Axis  76  extends substantially parallel to axis  58  and ground surface  60 . In this manner, geometrical variations in the size of tapered shank portion  68  and/or tapered aperture  62  do not vary a distance  80  measured from the wheel rotation axis  58  and the center of ball  66 .  
         [0023]     During the manufacture of knuckle  52 , a tool (not shown) is positioned distance  80  from axis  58  and translated along axis  76  to form tapered aperture  62 . Accordingly, the centerline of aperture  62  is properly positioned distance  80  from axis  58 . Therefore, variations in the size of aperture  62  or the size of tapered shank portion  68  will not vary the distance between the center of ball  66  and axis  58 .  
         [0024]      FIG. 3  depicts an alternate embodiment wheel suspension assembly  100 . Wheel suspension assembly  100  is substantially similar to wheel suspension assembly  50  except that a knuckle  102  includes a substantially spherical socket  104  and a control arm  106  includes a tapered aperture  108 . Ball stud  56  rotatably interconnects knuckle  102  and control arm  106 . Based on the horizontally aligned axis  76  of ball stud  56 , wheel suspension assembly  100  provides substantially similar advantages over the prior art as wheel suspension assembly  50 . Accordingly, like elements will retain their previously introduced reference numerals and wheel suspension assembly  100  will not be described in further detail.  
         [0025]      FIGS. 4-7  depict an alternate embodiment rear wheel suspension assembly  200 . Rear wheel suspension assembly  200  is substantially similar to wheel suspension assembly  100 . Accordingly, like elements will retain their previously introduced reference numerals. Furthermore, rear wheel suspension assembly  200  functions substantially similarly to wheel suspension assembly  100  in that ball stud  56  rotatably interconnects a knuckle  202  and a control arm  204 . Ball stud  56  is horizontally aligned substantially parallel to the ground  60 . In the embodiment shown in  FIGS. 4-7 , wheel  57  is not steerable but is rotatably coupled to rear wheel suspension assembly  200 . Rear wheel suspension assembly  200  is part of an independent-type suspension not shown in complete detail.  
         [0026]     Knuckle  202  includes a body portion  206 , an upper arm  208 , a lower arm  210 , a socket  212  and a dust shield  214 . Each of the portions numbered  206  through  214  are integrally formed with one another. It is contemplated that knuckle  202  may be formed by casting or forging materials such as magnesium, aluminum, cast iron or the like.  
         [0027]     Knuckle  202  is configured to accept a spindle (not shown) for rotatably supporting a hub (not shown) and wheel  57  for rotation about axis  58 . The spindle may be mounted to body portion  206 . Body portion  206  includes an aperture  216  extending therethrough. A stub shaft (not shown) may be drivingly coupled to a power source and may extend through aperture  216  to allow wheel  57  to be driven. One skilled in the art will appreciate that knuckle  202  may also be used in conjunction with non-driving axles without departing from the scope of the present invention.  
         [0028]     Upper arm  208  extends from body  206  and includes an aperture  218 . A suspension member (not shown) may be coupled to upper arm  208  with a fastener extending through aperture  218 . Similarly, lower arm  210  extends from body  206  and includes an aperture  220  extending therethrough. A suspension member (not shown) may be coupled to lower arm  210  via a fastener extending through aperture  220 .  
         [0029]     Socket  212  is formed in a boss  222 . Socket  212  has a center  223  and is sized to rotatably support ball stud  56  at a location substantially aligned with the wheel rotation axis  58 . More specifically, and as shown in  FIG. 4 , wheel rotation axis  58  and center  223  of socket  212  are aligned on a vertical centerline  224 . Vertical centerline  224  perpendicularly intersects the ground  60 . Dust shield  214  extends from body  206  and defines a semi-circular outer periphery. In this manner, dust shield  214  may be positioned proximate to wheel  57  without interfering with the wheel. Dust shield  214  functions to resist ingress of contamination to a brake (not shown) mounted on knuckle  202 .  
         [0030]      FIG. 8  depicts an alternate embodiment wheel suspension assembly  300 . Wheel suspension assembly  300  is substantially similar to the wheel suspension assemblies previously described except that the longitudinal axis  76  of ball stud  56  extends longitudinally along the length of the vehicle instead of transversely as previously depicted in  FIGS. 2-7 . Because the components included within wheel suspension assembly  300  are substantially similar to the wheel suspension assemblies previously described, like elements will retain their previously introduced reference numerals.  
         [0031]      FIG. 8  depicts ball  66  including a center  302  aligned along a vertical axis  304  passing through wheel rotation axis  58 . The forward vehicle direction of travel is indicated by arrow  306 . Accordingly, control arm  106  is located behind knuckle  102 . It should be appreciated that longitudinal axis  76  of ball stud  56  extends substantially parallel to ground surface  60  and is positioned a known distance  80  from wheel rotation axis  58 . In this manner, geometrical variations in the size of tapered shank portion  68  and/or tapered aperture  108  do not vary the distance  80 .  
         [0032]      FIG. 9  illustrates another alternate embodiment wheel suspension assembly  400 . Wheel suspension assembly  400  is substantially similar to wheel suspension assembly  300 . Accordingly, like elements will retain their previously introduced reference numerals. Wheel suspension assembly  400  differs from wheel suspension assembly  300  in that control arm  106  is positioned ahead of knuckle  102  with reference to vehicle forward direction  306 . Wheel suspension assembly  400  also includes longitudinal axis  76  of ball stud  56  being positioned substantially parallel to ground surface  60 . Accordingly, distance  80  is maintained much more accurately than is possible with a vertically oriented stud as previously described.  
         [0033]     Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.