Abstract:
A sway bar assembly has a tubular bar extending between two mounts. A pair of brackets mount the center section of the tubular bar to a vehicle. A first solid bar extends from the first mount to one of the brackets and a second solid bar extends from the second mount to the other bracket. The solid bars provide a redundancy of back-up features for the sway bar assembly.

Description:
FIELD 
       [0001]    The present disclosure relates to sway bars. More particularly, the present invention relates to a sway bar which includes a redundancy or backup safety feature. 
       BACKGROUND 
       [0002]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0003]    Sway bars or anti-roll bars are used in vehicles to adjust the torque of the suspension which then influences the roll rate. Sway bars are typically torsional springs which act across an axle to introduce resistance to relative changes in the displacement of one wheel on the axle compared to the displacement of the other wheel on the same axle. The sway bar or torsion spring is constrained both radially and axially and it is connected to the suspension member by a lever arm or by a linkage. The torsional spring rate or the sway bar contributes to the roll stiffness for the vehicle. 
         [0004]    Roll stiffness is important to both the ride comfort and the cornering ability of the vehicle. Too little roll stiffness results in excess body roll or lean and slow response to the rotation of the steering wheel by the driver. On the other hand, too much roll stiffness creates an uncomfortable ride and can cause a sudden loss of traction and the ability of the tires to stick to the road during cornering maneuvers. 
         [0005]    Sway bars are increasingly being required to withstand higher loads and stresses. Sway bars are typically formed from a bar or a tube having a generally circular cross-section. The bar is bent into the required shape to form arm sections and to fit and function in the particular vehicle application. Multi-piece sway bars are also known where a central bar is attached to a pair of spring elements or arm sections by welding or other means known in the art. The ends of the arm section of the sway bar connect to each end of the axle near the wheel typically with the bushings, ball joints, prop links or other methods known in the art. The center section is attached to the vehicle frame or other support structure using pivot connections. 
       SUMMARY 
       [0006]    The present disclosure provides a sway bar which has a redundancy (fail safe) or backup feature to hold the sway bar together should a component fail at a position outside the pivot connections for the center section. In the prior art, if a failure occurs in the position outside the pivot connections, the result is a complete loss of function of the sway bar and partial loss of axle stability typically requiring the immediate removal of the vehicle from service. The redundant or backup feature of the present disclosure will provide a limited function of the sway bar allowing the vehicle to continue to be driven prior to replacement or repair of the sway bar. 
         [0007]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0008]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0009]      FIG. 1  is a perspective view of the installation of a sway bar in accordance with the present disclosure; 
           [0010]      FIG. 2  is a perspective view of the sway bar and center section mounts illustrated in  FIG. 1 ; 
           [0011]      FIG. 3  is a perspective view, partially cross-section of the sway bar and center section mounts illustrated in  FIG. 1 ; and 
           [0012]      FIG. 4  is a cross-sectional view of one of the end assemblies of the sway bar illustrated in  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The following description is merely exemplary in nature and is not intended to limit the patent disclosure, application or uses. 
         [0014]    Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is illustrated in  FIG. 1  a typical vehicle suspension system  10 . Vehicle suspension system  10  comprises a frame or support member  12  (sprung component), a pair of axle assemblies (unsprung component)  14 , a plurality of springs  16 , a plurality of shock absorbers  18  and a pair of sway bar assemblies  20 . While sway bar assemblies  20  are illustrated in conjunction with a typical truck suspension, it is within the scope of the present disclosure to utilize sway bar assemblies  20  in any vehicle suspension system. 
         [0015]    Frame or support member  12  supports a fifth-wheel  30  which is utilized for the attachment of a trailer or other component to a cab (not illustrated) also supported by frame or support member  12 . Each axle assembly  14  supports a plurality of road wheels  32  as is well known in the art. Frame or support member  12  is attached to each of the axle assemblies  14  using four springs  16 . Springs  16  are illustrated as air springs but is within the scope of the present disclosure to utilize any type of spring in suspension system  10 . A pair of shock absorbers  18  extend between frame or support member  12  and each axle assembly  14  to dampen the motion between frame or support member  12  and axle assembly  14 . 
         [0016]    Each sway bar assembly  20  is attached between a respective axle assembly  14  and frame support member  12 . As illustrated in  FIG. 1 , a mounting bracket  34  mounts the center portion of each sway bar assembly  20  to each side of frame or support member  12  (only one side illustrated in  FIG. 1 ) and the ends of each sway bar assembly  20  are mounted to opposite sides of a respective axle assembly  14  adjacent a respective road wheel  32 . 
         [0017]    Referring now to  FIGS. 2 and 3 , sway bar assembly  20  and mounting brackets  34  are illustrated in greater detail. Sway bar assembly  20  comprises a pair of mounts in the form of bushing assemblies  40 , a pair of inner solid rods  42  and an outer tubular rod  44 . 
         [0018]    Each inner solid rod  42  is attached at one end to a respective bushing assembly  40  and its opposite end extends through mounting bracket  34  such that mounting bracket  34  supports the end of inner solid rod  42 . While inner solid rod  42  is illustrated as a solid rod, inner solid rod  42  can also be a tubular rod. Also, while sway bar assembly  20  is being illustrated as having two identical inner solid rods  42 , it is within the scope of the present disclosure to utilize two different inner solid rods to accommodate a specific application. 
         [0019]    Outer tubular rod  44  is attached at one end to one of the bushing assemblies  40  and is attached at its opposite end to the other bushing assembly  40 . Outer tubular rod  44  extends through both mounting brackets  34  such that the center section of the sway bar assembly  20  is supported by each mounting bracket  34 . Thus, as illustrated in  FIGS. 2 and 3 , each mounting bracket  34  supports both inner solid rod  42  and outer tubular rod  44 , both of which extend through mounting bracket  34  in a co-axial manner. Outer tubular rod  44  is designed to be press fit over inner solid rod  42 . 
         [0020]    Referring now to  FIG. 4 , one bushing assembly  40  is illustrated in greater detail. While sway bar assembly  20  is illustrated using two identical bushing assemblies  40 , it is within the scope of the present invention to utilize two different bushing assemblies to accommodate a specific application. Bushing assembly  40  comprises an outer member  50 , an inner member  52  and an elastomeric member  58  disposed between outer member  50  and inner member  52 . 
         [0021]    Outer member  50  includes a cylindrical housing  60  and an attachment cylinder  62  extending radially outward from cylindrical housing  60 . Inner member  52  extends through cylindrical housing  60  and it defines two holes  64  which are used to attach sway bar assembly  20  to axle assembly  14 . Elastomeric member  58  is disposed between inner member  52  and cylindrical housing  60  of outer member  50 . Inner solid rod  42  is attached to attachment cylinder  62  of the outer member  50  by welding or by other means known in the art. As illustrated in  FIG. 4 , attachment cylinder  62  is a solid cylindrical member which is welded to inner solid rod  42  as indicated at  66 . Outer tubular rod  44  is attached to cylindrical housing  60  of outer member  50  by welding or by other means known in the art as indicated at  68 . As illustrated in  FIG. 4 , attachment cylinder  62  is inserted into outer tubular rod  44 . 
         [0022]    Outer tubular rod  44  is designed to be the primary torsional member. During typical loading conditions, the stresses in outer tubular rod  44  will be significantly higher than the stresses in inner solid rod  42 . This will ensure that the backup feature, inner solid rod  42 , will remain intact should there be a failure of the primary member, outer tubular rod  44 . By having outer tubular rod  44  being designed as the primary torsional member, any failure of outer tubular rod  44  can be detected through routine inspection. Should outer tubular rod  44  fail, sway bar assembly  20  will remain intact due to inner solid rod  42  being held by mounting bracket  34  and extending to bushing assembly  40 . 
         [0023]    As illustrated, the welding of inner solid rod  42  to bushing assembly  40  and the welding of outer tubular rod  44  to bushing assembly  40  are staggered in the axial direction. The two welds can be in the same plane at the same axial position but the staggering of the two welds allows the weld between inner solid rod  42  and bushing assembly  40  to be supported by outer tubular rod  44  which is press fit over attachment cylinder  62  and inner solid rod  42 . 
         [0024]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.