Patent Publication Number: US-2004046336-A1

Title: Vehicle suspension system having a torsion spring assembly

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
     [0001] The present application claims priority of U.S. Provisional Application No. 60/405,136 filed Aug. 21, 2002, the entire disclosure of which is incorporated herein by reference. 
    
    
     
       TECHNICAL FIELD  
       [0002] The present invention relates generally to vehicle suspension systems, and more particularly to a vehicle suspension system having a torsion spring assembly.  
       BACKGROUND OF THE INVENTION  
       [0003] Conventional vehicle suspension systems include those having a vehicle suspension system lower control arm and a torsion spring assembly. The lower control arm has a first portion attached to the vehicle frame by a first bushing, a second portion attached to the frame by a second bushing, and a third portion attached to a knuckle by a ball joint. The torsion spring assembly includes a torsion tube and a torsion bar disposed within and radially spaced apart from the torsion tube. A first end of the torsion bar is attached to a first end of the torsion tube. A second end of the torsion bar extends beyond a second end of the torsion tube and is attached to the first bushing. The first or second end of the torsion tube is immobilized with respect to the vehicle frame to react torsional forces by being rigidly attached to the vehicle frame. A rotary damper assembly is operably connected to the torsion tube and the torsion bar. The vehicle has a lower control arm, an upper control arm, a torsion spring assembly, and a rotary damper assembly for each wheel. Such a vehicle suspension system carries spring vibrations to the occupants of the vehicle, as can be appreciated by those skilled in the art.  
       [0004] What is needed is an improved vehicle suspension system having a torsion spring assembly.  
       SUMMARY OF THE INVENTION  
       [0005] In a first expression of an embodiment of the invention, a suspension system for a vehicle includes a vehicle suspension system control arm, a torsion spring assembly, and a moment bar. The vehicle has a knuckle and a frame. The vehicle suspension system control arm has a first portion attachable to the frame by a first control-arm bushing, has a second portion attachable to the frame by a second control-arm bushing, and has a third portion attachable to the knuckle by a ball joint. The torsion spring assembly has a torsion tube and a torsion bar positioned within the torsion tube. A first end portion of the torsion bar is attached to a first end portion of the torsion tube, a second end portion of the torsion bar extend portions beyond a second end of the torsion tube and is attached to the control arm, and no portion of the torsion tube is immobilized with respect to the frame. The moment bar has a first end portion attached to the torsion tube and has a second end portion attachable to the frame.  
       [0006] A second expression of an embodiment of the invention is identical to the above first expression with the addition of a rotary damper assembly which is operably connected to the torsion tube and the torsion bar.  
       [0007] A third expression of an embodiment of the invention is identical to the above first expression with the addition of a controllable rotary damper assembly which is operably connected to the torsion tube and the torsion bar and which is operably connectable to an electronic control unit of a vehicle suspension control system.  
       [0008] Several benefits and advantages are derived from one or more of the expressions of an embodiment of the invention. Having a damper assembly, having no portion of the torsion tube be immobilized with respect to the frame, and having a moment bar with a first end portion attached to the torsion tube and a second end portion attachable to the frame lessens the effect of spring vibrations on the occupants of the vehicle. Having, in one example, the second end portion of the moment bar be attached to the torsion tube of an additional torsion spring assembly allows the torque on the moment bar from one side of the vehicle to be reacted by the other side of the vehicle through the additional torsion spring assembly and an additional rotary damper assembly of the other side of the vehicle greatly reducing the effect of spring vibrations on the occupants of the vehicle. Having the rotary damper assembly be a controllable rotary damper assembly provides controllable vehicle suspension while reducing the effect of spring vibrations on the occupants of the vehicle. 
     
    
    
     SUMMARY OF THE DRAWINGS  
     [0009]FIG. 1 is a schematic top planar view of an embodiment of the suspension system of the invention including a front-left-side lower control arm, a front-right-side lower control arm, and a moment bar;  
     [0010]FIG. 2 is longitudinal cross-sectional view of a portion of the suspension system of FIG. 1 including a portion of the front-left-side lower control arm;  
     [0011]FIG. 3 is an exploded perspective view of a portion of the suspension system of FIG. 1 including the front-left-side lower control arm and the addition of a front-left-side upper control arm; and  
     [0012]FIG. 4 is a longitudinal cross-sectional view of an alternate embodiment of the moment bar of FIG. 1. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0013] Referring now to the drawings, wherein like numerals represent like elements throughout, FIGS.  1 - 3  show an embodiment of the present invention. A first expression of the embodiment of FIGS.  1 - 3  is for a suspension system  10  for a vehicle  12 , wherein the vehicle  12  has a knuckle  14  and a frame  16 . Only a portion or portions of the vehicle  12  and the frame  16  are shown in the figures. The suspension system  10  includes a vehicle suspension system control arm  24 , a torsion spring assembly  26 , and a moment bar  28 . The control arm  24  has a first portion  30  attachable to the frame  16  by a first control-arm bushing  32 , has a second portion  34  attachable to the frame  16  by a second control-arm bushing  36 , and has a third portion  38  attachable to the knuckle  14  by a ball joint  40 . The torsion spring assembly  26  has a torsion tube  42  and a torsion bar  44  disposed within the torsion tube  42 . A first end portion  46  of the torsion bar  44  is attached to a first end portion  48  of the torsion tube  42 . A second end portion  50  of the torsion bar  44  extend portions beyond a second end  52  of the torsion tube  42  and is attached to the control arm  24 . No portion of the torsion tube  42  is immobilized with respect to the frame  16 . The moment bar  28  has a first end portion  54  attached to the torsion tube  42  and has a second end portion  56  attachable to the frame  16 . It is noted that the term “attached” includes directly attached or indirectly attached, and that the term “attachable” includes directly attachable or indirectly attachable.  
     [0014] In one example of the first expression of the embodiment of FIGS.  1 - 3 , the vehicle  12  has a longitudinal axis  18  dividing the frame  16  into a first side  20  and a second side  22 , wherein the first portion  30  is attachable to the first side  20  by the first control-arm bushing  32 , and wherein the second portion  34  is attachable to the first side  20  by the second control-arm bushing  36 . The longitudinal axis  18  runs front to back through the middle of the vehicle dividing it into a left half and a right half. The expression “first side” includes any and all portions of the vehicle frame that are located to one side (e.g., the left or the right) of the longitudinal axis. Likewise, the expression “second side” includes any and all portions of the vehicle frame that are located to the other side of the longitudinal axis.  
     [0015] In one arrangement of the first expression of the embodiment of FIGS.  1 - 3 , the knuckle  14  is associated with the left-front wheel  58  of the vehicle  12 . In one assemblage, the suspension system  10  also includes a vehicle suspension system same-side control arm  60  (seen only in FIG. 3) which is attachable to the knuckle  14 . In one variation, a damper assembly  62  is operably connected to the control arm  24  (seen in FIGS. 1 and 2) or the same-side control arm  60  (seen only in FIG. 3). In one modification, the control arm  24  is a lower control arm, and the same-side control arm  60  is an upper control arm. In one design, the moment bar  28  is a substantially transversely extending moment bar, and the first end portion  54  of the moment bar  28  is attached to the torsion tube  42  proximate the second end  52  of the torsion tube  42  (such as being indirectly attached via a connecting member  64 ).  
     [0016] In one enablement of the first expression of the embodiment of FIGS.  1 - 3 , the suspension system  10  includes a vehicle suspension system additional control arm  66  which is a substantial mirror image about the longitudinal axis  18  of the control arm  24 . In this enablement, the suspension system  10  also includes an additional torsion spring assembly  68  which is a substantial mirror image about the longitudinal axis  18  of the torsion spring assembly  26 . In this enablement, the second end portion  56  of the moment bar  28  is indirectly attached to the second side  22  by being attached to the torsion tube  70  of the additional torsion spring assembly  68 . The vehicle&#39;s right-front wheel  72  is shown in FIG. 1 in association with the additional control arm  66 .  
     [0017] In one construction of the first expression of the embodiment of FIGS.  1 - 3 , the moment bar  28 , shown in FIGS. 1 and 2, is not a telescoping moment bar and has no outer portion and slideable inner portion. FIG. 4 shows an alternate embodiment of a moment bar  74 . In FIG. 4, the moment bar  74  includes an outer portion  76  and an inner portion  78  disposed coaxially and slideably within the outer portion  76 . In this embodiment, the first end portion  80  of the moment bar  74  is an end portion of the outer portion  76 , and the second end portion  82  of the moment bar  74  is an end portion of the inner portion  78 . In one variation, the moment bar  74  includes an elastomer  84  disposed between the inner and outer portions  78  and  76 . In one modification, the elastomer  84  forms a press fit with the inner and outer portions  78  and  76 .  
     [0018] In one illustration of the first expression of the embodiment of FIGS.  1 - 3 , the torsion tube  42  and the moment bar  28  lie substantially in a horizontal plane when the vehicle  12  is horizontal. In one variation, the torsion spring assembly  26  and the additional torsional spring assembly  68  are associated with the corresponding left and right front wheels  58  and  72  of the vehicle  12 , are substantially parallel to the longitudinal axis  18 , and extend toward the rear of the vehicle  12  as shown in FIG. 1.  
     [0019] A second expression of the embodiment of FIGS.  1 - 3  is for a suspension system  10  for a vehicle  12 , wherein the vehicle  12  has a knuckle  14  and a frame  16 . The suspension system  10  includes a vehicle suspension system control arm  24 , a torsion spring assembly  26 , a moment bar  28 , and a rotary damper assembly  86 . The control arm  24  has a first portion  30  attachable to the frame  16  by a first control-arm bushing  32 , has a second portion  34  attachable to the frame  16  by a second control-arm bushing  36 , and has a third portion  38  attachable to the knuckle  14  by a ball joint  40 . The torsion spring assembly  26  has a torsion tube  42  and a torsion bar  44  disposed within the torsion tube  42 . A first end portion  46  of the torsion bar  44  is attached to a first end portion  48  of the torsion tube  42 . A second end portion  50  of the torsion bar  44  extends beyond a second end  52  of the torsion tube  42  and is attached to the control arm  24 . No portion of the torsion tube  42  is immobilized with respect to the frame  16 . The moment bar  28  has a first end portion  54  attached to the torsion tube  42  and has a second end portion  56  attachable to the frame  16 . The rotary damper assembly  86  is operably connected to the torsion tube  42  and the torsion bar  44 .  
     [0020] In one implementation of the second expression of the embodiment of FIGS.  1 - 3 , the rotary damper assembly  86  includes a cylinder  88  surrounding the torsion bar  44  and attached to the second end  52  of the torsion tube  42  and having radially-inwardly extending plates  90 . In this implementation, the rotary damper assembly  86  also includes radially-outwardly extending plates  92  attached to the torsion bar  44  and interleaved with the radially-inwardly extending plates  90 . The rotary damper assembly  86  further includes a damping fluid (not shown) and seals (not shown). In one option, the rotary damper assembly  86  is a passive rotary damper assembly (not shown). It is noted that the examples, variations, modifications, etc. of the first expression of the embodiment of FIGS.  1 - 3  are equally applicable to the second expression.  
     [0021] A third expression of the embodiment of FIGS.  1 - 3  is for a suspension system  10  for a vehicle  12 , wherein the vehicle  12  has a knuckle  14  and a frame  16 . The suspension system  10  includes a vehicle suspension system control arm  24 , a torsion spring assembly  26 , a moment bar  28 , and a controllable rotary damper assembly  94 . The control arm  24  has a first portion  30  attachable to the frame  16  by a first control-arm bushing  32 , has a second portion  34  attachable to the frame  16  by a second control-arm bushing  36 , and has a third portion  38  attachable to the knuckle  14  by a ball joint  40 . The torsion spring assembly  26  has a torsion tube  42  and a torsion bar  44  disposed within the torsion tube  42 . A first end portion  46  of the torsion bar  44  is attached to a first end portion  48  of the torsion tube  42 . A second end portion  50  of the torsion bar  44  extends beyond a second end  52  of the torsion tube  42  and is attached to the control arm  24 . No portion of the torsion tube  42  is immobilized with respect to the frame  16 . The moment bar  28  has a first end portion  54  attached to the torsion tube  42  and has a second end portion  56  attachable to the frame  16 . The controllable rotary damper assembly  94  is operably connected to the torsion tube  42  and the torsion bar  44  and is operably connectable to an electronic control unit  96  of a vehicle suspension control system  98  (only the electronic control unit portion of which is shown in the figures).  
     [0022] In one example of the third expression of the embodiment of FIGS.  1 - 3 , the controllable rotary damper assembly  94  is an MR (magnetorheological) rotary damper assembly. Other examples include, without limitation, MSR (manually selectable ride) rotary damper assemblies and RTD (real time damping) rotary damper assemblies. It is noted that the examples, variations, modifications, etc. of the first and/or second expressions of the embodiment of FIGS.  1 - 3  are equally applicable to the third expression.  
     [0023] Several benefits and advantages are derived from one or more of the expressions of an embodiment of the invention. Having a damper assembly, having no portion of the torsion tube be immobilized with respect to the frame, and having a moment bar with a first end portion attached to the torsion tube and a second end portion attachable to the frame lessens the effect of spring vibrations on the occupants of the vehicle. Having, in one example, the second end portion of the moment bar be attached to the torsion tube of an additional torsion spring assembly allows the torque on the moment bar from one side of the vehicle to be reacted by the other side of the vehicle through the additional torsion spring assembly and an additional rotary damper assembly of the other side of the vehicle greatly reducing the effect of spring vibrations on the occupants of the vehicle. Having the rotary damper assembly be a controllable rotary damper assembly provides controllable vehicle suspension while reducing the effect of spring vibrations on the occupants of the vehicle.  
     [0024] The foregoing description of several expressions and embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.