Patent Publication Number: US-7216879-B2

Title: Reconfigurable strut assembly

Description:
This application is a Divisional of U.S. patent application Ser. No. 10/349,726 filed on Jan. 23, 2003 now U.S. Pat. No. 6,997,467. 

   BACKGROUND OF THE INVENTION 
   This invention relates to a suspension system for a passenger vehicle, and more particularly, the invention relates to a reconfigurable strut assembly including an integrated strut cylinder and knuckle for use on at least two and preferably all of the corners of a vehicle. 
   Vehicle suspension designs typically use an individual knuckle at each corner of a vehicle to allow for various lower suspension geometry. Specifically, the orientation and attachment of the brakes, steering components, struts relative to the vehicle body, and other features are particular to each corner of the vehicle such that a unique strut and knuckle is required at each corner of the vehicle. That is, the front and rear struts and knuckles are different, and the left and right struts and knuckles are different. Furthermore, the knuckle designs are often specific only to one vehicle line. The lack of interchangeability of struts and knuckles within a vehicle line and with other vehicles adds significant tooling costs to the suspension component. Therefore, what is needed is an interchangeable strut assembly that may be used on more than one corner of a vehicle and across vehicle lines. 
   SUMMARY OF THE INVENTION AND ADVANTAGES 
   The present invention provides a vehicle with front and rear suspension systems. The vehicle includes front left and right strut assemblies respectively including front left and right knuckles. Rear left and right strut assemblies respectively include rear left and right knuckles. The knuckles are common with one another with each knuckle having a common lower attachment boss. The front left and right knuckles respectively receive front left and right connection members at the lower attachment boss. The lower attachment boss is respectively interconnected to the front left and right suspension components. The rear left and right knuckles respectively receive rear left and right connection members at the lower attachment boss respectively interconnected to rear left and right suspension components. The overall suspension for the vehicle is designed by determining the left knuckle position parameters such as suspension member, brake, and wheel assembly attachment points. Similarly, the right knuckle position parameters are determined. Alternatively and/or additionally, front and rear knuckle portion parameters may be determined. Common vehicle attachment points on the knuckles are then calculated for the vehicle. Several iterations of the above design process may take place to commonize the suspension for a particular vehicle or across particular vehicle lines. 
   Accordingly, the above invention provides an interchangeable strut assembly that may be used on more than one corner of a vehicle and across vehicle lines. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages of the present invention can be understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
       FIG. 1  is a top elevational schematic view of a front and rear suspension system for a vehicle; 
       FIG. 2  is a side elevational view of a common front strut assembly for the vehicle shown in  FIG. 1 ; 
       FIG. 3  is a side elevational view of a rear strut assembly for the vehicle shown in  FIG. 1 ; and 
       FIG. 4  is a block diagram of the present invention design process for designing and manufacturing interchangeable strut assemblies for a vehicle or between vehicle lines. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention provides a single integrated strut and knuckle casting that can be used on different corners of a particular vehicle and even across vehicle lines by commonizing the basic structure of the strut-knuckle and various bolt-on attachments. The attachments provide for several lower geometry configurations providing the ability of the knuckle to be used on all four corners of the vehicle as well as across vehicle lines. 
   A vehicle  10  is shown in  FIG. 1 . The vehicle  10  includes a front suspension system  12  and a rear suspension system  14 . The front suspension system  12  includes front left  18  and front right  20  strut assemblies each supporting wheels  16 . Although the suspension components for a particular vehicle may be different than shown, the depicted front suspension system  12  utilizes a McPherson strut geometry. The front left strut assembly  18  includes a left lower control arm  22  connected to the vehicle frame  11  by left pivotal frame connections  26 , as is known in the art. Similarly, the front right strut assembly  20  includes a right lower control arm  24  pivotally connected to the vehicle frame  11  by a right pivotal frame connections  28 , as is known in the art. The strut assemblies  18  and  20  are connected between the vehicle frame  11  and are attached to the lower control arms  22  and  24  typically by a ball joint, which is discussed in more detail below. 
   The rear suspension system  14  includes left rear  32  and right rear  34  strut assemblies. The rear suspension system  14  is of an independent trailing arm configuration. The left rear strut assembly  32  is connected to the vehicle frame  11  at the upper portion and is supported at the lower portion by a pair of spaced apart left lateral links  36  and  38 . A longitudinal link  40  is connected between the lower portion of the strut assembly and the vehicle frame  11 . The lateral  36 ,  38  and longitudinal  40  left links are pivotally supported on the vehicle frame  11  respectively by a pair of left lateral  42  and a forward  44  pivotal frame connections. Similarly, the right rear strut assembly  34  is supported by the vehicle frame  11  at an upper portion. The lower portion of the right rear strut assembly  34  is supported by a pair of spaced apart right lateral links  46  and  48 . A longitudinal link  50  is interconnected between the lower portion of the strut assembly  34  and the vehicle frame  11 . The right lateral links  46  and  48  and longitudinal link  50  are pivotally supported on the vehicle frame  11  respectively by a pair of right lateral  52  and a forward  54  pivotal frame connections. 
   The front suspension system  12  and rear suspension system  14  described above is merely illustrative of two suspension configurations to which the present invention may apply. That is, the reconfigurable strut assembly described in further detail below may be used for suspension configurations other than those described above or depicted in the figures. 
   A rear strut assembly is depicted in  FIG. 2 . The strut assembly includes an integrated strut cylinder  51  and knuckle  53 . The integrated strut cylinder  51  and knuckle  53  may be manufactured of a single metal casting. The strut assembly includes an upper attachment point  57  that may include fasteners  55  for attaching the upper portion of the strut assembly to the vehicle frame  11 . A spring  59  is shown arranged between the upper attachment point  57  and the cylinder  51 , although an air bag may also be used. The knuckle  53  includes a lower attachment boss  56  to which a connection member  58  may be attached using fastening elements. It is most desirable that the strut cylinder  51 , knuckle  53 , and lower attachment boss  56  be common for both sides of the rear strut assemblies, and preferably the strut assemblies for both the front and rear of the vehicle. Alternatively, these may be interchangeable between strut assemblies on only one side. The connection member  58  may provide a plurality of attachment points  60 ,  61  and  62  specific to the left or right side of the rear suspension system  14 . For a strut assembly common to both the front and rear suspension system, a connection member may be provided for each side of the front suspension system, as will be discussed relative to  FIG. 3  below. 
   With continuing reference to  FIG. 2 , the knuckle  53  includes a brake attachment feature  64  and wheel assembly attachment feature  66  that are common to both sides of the rear suspension system and preferably all four corners of the vehicle. In this manner, the strut cylinder  51  and knuckle  53  may be oriented differently for the front and rear and left and right side of the vehicle. The attachment features  64  and  66  and lower attachment boss  56  may be generally coplanar so that they may be rotated 180° from one side to the other. 
   The damping characteristics of the strut assembly may be tailored for the front or rear suspension of a vehicle or between vehicle lines by providing an external valve housing  68  extending from a portion of the strut cylinder  51 . Depending upon the desired damping for the application, a particular valve assembly  70  may be installed within the external valve housing  68  to provide the desired damping characteristics for the application. In this manner, the reconfigurable strut assembly may be more specifically tailored for the desired application so that the flexibility using the common design of the present invention is not sacrificed. 
   Referring to  FIG. 3 , a front suspension strut assembly is shown. A different connection member  72 , such as a ball joint may be secured to the lower attachment boss  56  to provide the particular attachment feature typically used for a McPherson strut configuration. A different valve assembly  74  may be installed in the external valve housing  68  to provide a damping characteristic for the front suspension that is different than the rear suspension. Components such as the upper attachment point  57  and the spring element  59  may also be varied. 
   Referring to  FIG. 4 , the design process for the present invention reconfigurable strut assembly requires the consideration of various design features for the left and right sides and front and rear sides of a particular vehicle and potentially between or across vehicle lines. First, the desired attachment points such as brake attachment features, wheel assembly attachment features, and upper and lower attachment points must be determined, as indicated in block  76 . The vehicle attachment points must then be commonized by calculating the most desirable attachment points for the strut assemblies, as shown at block  78 . Several iterations of the design process depicted in  FIG. 4  may be required to obtain the desired common strut assembly. 
   The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.