Abstract:
The present invention relates to an independent rear vehicle suspension that comprises a fore/aft link with first and second ends, where a bracket pivotally supports the first end of the fore/aft link from a vehicle frame member. The fore/aft link has an air bag spring located between the fore/aft link&#39;s second end and the frame member. A lateral link pivotally connects between the fore/aft link&#39;s second end and the vehicle frame. A wheel upright, with an axle aperture extending through it, is rigidly attached near to the second end of the fore/aft link and located above the fore/aft link. An upper control rod is pivotally connected to the wheel upright and pivotally mounted to the frame member.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an independent rear vehicle suspension. More particularly, the present invention relates to a short and long arm independent rear vehicle suspension that utilizes air bag springs.  
       BACKGROUND OF THE INVENTION  
       [0002]     Those skilled in the art know that a vehicle has a suspension for supporting the upper part of the vehicle on the vehicle&#39;s axles. In some vehicles, a suspension on one side is independent from a suspension on the other side. Also, some suspensions utilize short and long mechanical arms (SLA), and/or air bag springs to provide support for the upper part of the vehicle.  
         [0003]     Examples of relevant art involving vehicle suspensions are as follows. U.S. Pat. No. 3,630,541 to Carlson et al. teaches a vehicle axle suspension having a bracket  16  attached to a frame member  12 . The bracket has a pivotal connection  18  for supporting a trailing arm  17 . The axle is bolted to the trailing arm by two U-bolts. An air spring unit  19  is located between the trailing arm  17  and the frame.  
         [0004]     U.S. Pat. No. 4,858,949 to Wallace et al. provides for a trailing arm suspension having a frame bracket assembly  18  attached to a frame member. A trailing arm  16  is pivotally attached to the frame bracket assembly  18 . A clamping assembly  28  secures the axle below the trailing arm with a plurality of elongated bolts. An air spring assembly  22  is secured to the rear of the trailing arm between the trailing arm and the frame. A track bar  115  is attached to the frame to resist side-to-side motion. The track bar is not attached to the trailing arm.  
         [0005]     However, a vehicle would benefit from a light weight and inexpensive independent rear suspension that utilizes SLA technology with an air bag spring.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention relates to a vehicle suspension that comprises a fore/aft link having a first end and a second end, a bracket for pivotally supporting the first end of the fore/aft link, from a portion of a vehicle frame, an air bag spring located between the second end of the fore/aft link and the vehicle frame, a lateral link pivotally connected proximate the second end of the fore/aft link and a portion of the vehicle frame, and a wheel upright having an axle aperture extending therethrough above the fore/aft link, rigidly attached proximate the second end of the fore/aft link.  
         [0007]     Further advantages of the present invention will be apparent from the following description and appended claims, reference being made to the accompanying drawings forming a part of a specification, wherein like reference characters designate corresponding parts of several views.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a top view of a vehicle in accordance with the present invention;  
         [0009]      FIG. 2  is a side elevation view of a rear suspension of the vehicle of  FIG. 1 ;  
         [0010]      FIG. 3  is a rear view of the vehicle suspension of  FIG. 2 ; and  
         [0011]      FIG. 4  is a top view of the vehicle suspension of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]     It is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions, directions or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless the claims expressly state otherwise.  
         [0013]      FIG. 1  illustrates a vehicle  11  having front wheel assemblies  22 a, b and an engine  12  that drives a transmission  13 , which drives a main drive shaft  14  that is coupled to a rear wheel differential  15 . In turn, the rear wheel differential  15  drives left and right half axles  16   a, b  that, respectively, independently drive left and right rear wheel assemblies  17   a, b.    
         [0014]     Also shown in  FIG. 1  are individual short and long mechanical arms (SLA) rear vehicle suspensions  10   a, b  (i.e., one for each side of the vehicle  11 ). The suspensions  10   a, b  support the rear upper part (not shown) of the vehicle  11  by way of respective frame members  18   a, b,  where each of the rear suspensions  10   a, b  is independent of the other suspension  10   b, a.  Even though shown separately in  FIG. 1 , the frame members  18   a, b  may be one frame.  
         [0015]     Although  FIGS. 2-4  illustrate the suspension  10   b,  the individual rear suspensions  10   a, b  are essentially the same. Specifically referring to  FIG. 2 , there is shown a side view of a preferred embodiment of the suspension  10   b.  A hanger bracket  19   b,  which has a pivot aperture  23   b  therethrough, is disposed on a frame member  18   b.  A fore/aft link  21   b  is pivotally supported at a first end  26   b  at the bracket pivot aperture  23   b,  where a bracket bushing  41   b  is disposed.  
         [0016]     An air bag spring  20   b  (which may have an internal jounce bumper spring(s) that is not shown) is located between a second end  27   b  of the fore/aft link  21   b  and the frame member  18   b.  Those skilled in the art understand that another type of spring, such as a coil spring, may alternately be utilized. A lateral link  28   b  is pivotally connected at the second end  27   b  of the fore/aft link  21   b.  It is a discovery of the present invention that, in combination, the fore/aft link  21   b  and the lateral link  28   b  effectively form a lower control arm, which is known in the art as a long arm. A wheel upright  24   b  (shown in cross-section) is rigidly attached near the second end  27   b  of the fore/aft link  21   b,  where the wheel upright  24   b  has a second half axle aperture  25   b  that allows the second half axle  16   b  to rotate therethrough.  
         [0017]      FIG. 3  depicts a rear view of the suspension  10   b  between the rear wheel differential  15  and the rear wheel assembly  17   b.  An upper control rod  33   b  (a short arm that is a simple radius rod, with upper control rod bushings  42   b  and  43   b  disposed therein) is pivotally connected to the wheel upright  24   b  (shown in cross-section) and pivotally mounted to the frame member  18   b.  Also shown in  FIG. 3  is the lateral link  28   b  connected at the second end  27   b  of the fore/aft link  21   b.  The lateral link  28   b  (with lateral link bushings  44   b  and  45   b  disposed therein) is also attached to the frame member  18   b.  For the sake of clarity, several brackets and cross members needed to mount the suspension and drive mechanisms have been omitted. However, these brackets and cross members would be of standard construction.  
         [0018]     The rear wheel differential  15  drives the independent second half axle  16   b,  which rotates the stub shaft  31   b,  thereby rotating wheels  30   b  and tires  29   b,  and moving the vehicle  11 . Also shown is a brake drum  32   b  that is utilized for slowing and stopping the vehicle  11 .  
         [0019]      FIG. 4  provides a top view of the suspension  10   b.  The hanger bracket  19   b  is shown supporting the first end  26   b  of the fore/aft link  21   b  from the frame member  18   b.  Also shown is the air bag spring  20   b  located between the second end  27   b  of the fore/aft link  21   b  and the frame member  18   b,  and the lateral link  28   b  that is connected at the second end  27   b  of the fore/aft link  21   b.    
         [0020]     It is a discovery of the instant invention that a lower control arm pivot axis  35   b  is thereby formed by the combination of the fore/aft link  21   b  and the lateral link  28   b.  The pivot axis  35   b  extends from a center point  36   b  of the pivot aperture  23   b  to a center point  38   b  of a lateral link attachment at the frame member  18   b.    
         [0021]     As a result of the pivot axes  35 , the present invention allows for the fore/aft links  21  to be robust so as to carry large spring loads from the air bag springs  20  (and accompanying jounce bumper springs), and yet at the same time laterally stabilize the suspensions  10   a, b  with light weight (and less expensive) lateral links  28 . Additionally, it is felt that the upper control rods  33  can be of simple, low cost, and light in weight, with the single outboard and inboard bushings  42 - 43 . These control rods  33  would be in contrast to the conventional triangular shaped upper control rods with two inboard bushings.  
         [0022]     Further, the lower links (i.e., the fore/aft links  21  and lateral links  28 ) spread out lower link loads on the frame members  18 . The fore/aft links geometry, as shown in  FIGS. 2-4 , allows the air bag springs  20  a motion ratio that reduces the spring load required from the air bag springs  20 . Therefore, a single air bag spring  20  per side (left or right) is utilized. A minimum number (e.g., five per side) of the bushings  41 - 45  are utilized to connect the wheel uprights  24  and the frame members  18  to the suspension links  21 ,  28 ,  33 .  
         [0023]     The frame loading in the present invention is similar to traditional suspension frame loading, however, good lateral stability is obtained with the use of the lateral links  28 . Good braking and drive torque reaction are obtained with the long distance pivot axes  35 .  
         [0024]     Thus, the fore/aft links  21  and the lateral links  28  allow a beneficial motion ratio for the air bag springs  20  and shock absorbers (not shown), allow a wide based frame member load distribution, and allow a cost effective construction. The outer bushing attachments of the wheel uprights  24  to the suspensions  10   a, b  are reduced to only one outboard bushing  42  per side, and the wheel uprights  24  are rigidly attached to the fore/aft links  21 .  
         [0025]     In the present invention, as the wheels  30  travel in jounce and rebound, the wheel uprights  24  follow a path determined by the radius of the upper control rod  33  and the lateral links  28 , in combination with the bushing deflection compliances. Camber is controlled due to the positioning of the upper control rod  33  and lower control arm  21 ,  28 , shown in the rear view (i.e.,  FIG. 3 ), and the effective length of the lower lateral links  28  relative to the axle lateral center line (refer to  FIG. 4 ).  
         [0026]     The present invention embodies an independent rear suspension (IRS) (see first and second half axles  16   a, b ), which does not have a rigid beam axle construction. The fore/aft link  21  carries a bending load from the air bag spring loads and wheel loads that are then stabilized laterally with the lateral links  28 . Due to the design of the combination of the lower links  21 ,  28  and the upper links  33 , the present invention results in significantly different kinematics than a dependent rear vehicle suspension.  
         [0027]     In accordance with the provisions of the patent statutes, the principles and modes of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that the invention may be practiced otherwise than specifically explained and illustrated without departing from its spirit or scope.