Abstract:
A torsion bar suspension for an automotive vehicle includes powered means for remotely adjusting the trim height of the vehicle by varying the torque applied to the torsion bars. Height adjustment may be up or down or both from a normal running height. The suspension may be made capable of lowering vehicle height to allow entry into or passage through a low clearance location, such as a parking garage or overpass. Alternatively, the suspension could be capable of raising the vehicle height for passage over rough terrain. Various embodiments of adjusting mechanisms are disclosed including, for example, lever and wheel type torsion adjusting means with linear or rotary actuators.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/143,792, filed Jul. 14, 1999. 
    
    
     TECHNICAL FIELD 
     This invention relates to vehicle suspensions and, more particularly, to a torsion bar type suspension with power trim height adjusting means. 
     BACKGROUND OF THE INVENTION 
     It is known in the art to provide a vehicle suspension including torsion bars as the vehicle-supporting spring elements. In a typical embodiment, a torsion bar is connected with the lower control arm connecting an associated one of the vehicle wheels with the vehicle body. The torsion bar typically extends longitudinally, having an opposite end supported in a frame or body cross member. The cross member supported end is attached to a torsion lever which applies a predetermined torsion force for supporting the vehicle. An adjusting screw mounted in either the cross member or the lever engages the other for manually adjusting the lever to provide the desired torque setting of the torsion bar. 
     SUMMARY OF THE INVENTION 
     The present invention provides power adjustable means for remotely varying the torque applied to the torsion bars of a vehicle torsion bar suspension so that the trim height of the suspension may be remotely controlled by the vehicle operator. The height adjustment may be up or down from a normal running height. The suspension may be made capable of lowering vehicle height to allow entry into or passage through a low clearance location, such as a parking garage or overpass. Alternatively, the suspension could be capable of raising the vehicle height for passage over rough terrain. Various forms of adjusting mechanisms may be utilized including, for example, lever and wheel type torsion adjusting means with linear or rotary actuators. 
     For example, the torsion member may be a torsion lever similar to that of the manually adjusted prior art embodiment. A linear actuator is provided between the torsion lever and the vehicle cross member to adjust the torsion lever in response to an operator initiated signal. The linear actuator may be of any suitable type, such as a pneumatic or hydraulic cylinder or device, or an electric motor driven actuator, such as a powered screw or the like. The actuator is adjustable to at least two positions and rotates the torsion lever between these positions to establish either a high or low height position of the vehicle suspension in which the vehicle can be operated. 
     For some types of actuators, such as a hydraulic cylinder or bag, position locks may be required to fix the associated torsion levers in their adjusted positions so that the spring rates of the torsion bar suspension will not be changed by the effect of the pneumatic actuator applied as part of the system. To adjust the mechanism, the locks would first be released so that the actuators could move the torsion levers to another position after which the locks would again be applied, if required. 
     A feature of these embodiments of the invention is that they may be relatively easily applied to an existing torsion bar suspension system that does not have a remotely adjustable trim height feature. The modifications to the existing system would only affect a part of the vehicle to which the torsion bars are anchored and would involve packaging of the lever arm actuator and lock/latch mechanism, if required. 
     In other embodiments of the invention, the torsion member could be a wheel, such as a sprocket, gear or the like, driven by a power drive of any suitable type, One example is an electric motor driven worm drive connected to a chain drive sprocket. The drive sprocket is connected by chain connectors with driven adjuster sprockets on both of the torsion bars supporting one end of a vehicle. Remotely controlled operation of the worm drive actuates both driven sprockets to adjust both torsion bars simultaneously to vary the vehicle trim height at the associated vehicle end. 
     These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is an exploded pictorial view of a suspension according to the invention and intended for use at one end of a vehicle; 
     FIG. 2 is a fragmentary exploded pictorial view of an actuating mechanism for an alternative embodiment; 
     FIG. 3 is a cross-sectional rear view showing the mechanism of FIG. 2 in a lowered trim height position; 
     FIG. 4 is a view similar to FIG. 3 showing the mechanism in a raised trim height position; 
     FIG. 5 is a view similar to FIG. 2 showing another alternative embodiment; and 
     FIGS. 6 and 7 are views similar to FIGS. 3 and 4 showing, respectively, the mechanism of FIG. 5 in lowered and raised trim height positions; 
     FIG. 8 is a rear cross-sectional view of a fourth embodiment of the invention; 
     FIG. 9 is an exploded rear pictorial view of a fifth embodiment; and 
     FIG. 10 is a side view of associated drive sprockets in the embodiment of FIG.  9 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1 of the drawings in detail, numeral  10  generally indicates a first embodiment of torsion bar suspension with power height adjustment for an automotive vehicle. Suspension  10  includes a body cross member  12  which is preferably attached to longitudinal frame or body members, not shown. The embodiment of FIG. 1 represents various forms of torsion bar suspensions which may be used as front or rear suspensions of a vehicle. 
     In the illustrated embodiment, suspension  10  is applied to an independent suspension which is typically the front suspension of a vehicle, although it could be equally well be used in an independent rear suspension. The suspension shown includes a pair of longitudinal torsion bars  14 . In the particular embodiment illustrated, the torsion bars  14  have hexagonal front ends  16  which are received within hexagonal openings  18  in lower control arms  20  of a vehicle front suspension. The control arms  20  have inner ends  22  which are conventionally pivotally attached to the vehicle frame or body, not shown, and outer ends  24  which each connect with or support a spindle, not shown, of an associated wheel of the vehicle. 
     Torsion bars  14  also have opposite rear ends  26  which extend into openings  28  in the cross member  12 . The rear ends  26  are also hexagonally shaped and are received in hexagonal openings  30  of torsion levers  32  that are carried within the cross member  12  in alignment with the openings  28 . The torsion levers have outer ends  34  distal from the openings  30  and extending beneath outer ends  36  of the cross member  12 . 
     Linear actuators  38  are mounted between the outer ends  36  of the cross member and the outer ends of the corresponding torsion levers extending therebelow. The linear actuators  38  may be of any suitable type, such as pneumatic, hydraulic, electrically actuated screw or the like, and are operable to extend or contract in order to rotate the torsion levers around the axes of the torsion bars to which they are connected and between upper and lower positions of the outer ends of the torsion levers. 
     The suspension may also include, as illustrated, locks  40  which are pivotally mounted on pins  42  in openings  44  of the cross member  12 . The locks  40  have outwardly facing notches  46  which are engagable with lock protrusions  48  extending from the torsion bars at inner ends adjacent their openings  30 . A lock release mechanism, such as cables attached to the lower ends of the lock members, may be required for disengaging them from the lock protrusions when a change in the adjusting position is required. Any suitable form of lock release devices, not shown, may be utilized. 
     Operation of the suspension mechanism as above described will be discussed subsequently in connection with a slightly modified alternative embodiment illustrated in FIGS. 2-4. In these figures, numeral  50  generally indicates the slightly modified embodiment, only a portion of which is shown. Suspension  50  is carried by a longitudinal member  52  of the frame or body of an associated vehicle. A cross member  54 , one end of which is shown, is attached to the longitudinal member  52  and to a like member on the other side of the vehicle body. The cross member includes, at the illustrated end, openings  28  which are formed in the sides of a U-shaped portion of the cross member  54  having a downwardly facing open side. 
     The inner end  56  of a torsion lever  58  is received in the U-shaped portion with a hexagonally shaped opening  30  aligned on the axis of openings  28 . The lever  58  extends outward to an outer end  60  which is attached to a linear actuator  62  that also engages an outer end of the cross member  54 . A torsion bar  14  of the suspension includes a hexagonally shaped rear end  26 , as in the first described embodiment. The torsion bar is twisted to provide the desired torque, after which the rear end  26  is inserted through one of the openings  28  into the hexagonal opening  30  of the torsion lever. This locks the torsion bar in place and applies a desired torque to the associated control arm at the other end of the torsion bar which thereby lifts the vehicle body to a predetermined desired trim height. 
     The linear actuators  62  may be of any desired type but, in the embodiment of FIGS. 2-4, as illustrated, the use of hydraulic or electrically actuated mechanical screw type actuators might be preferable. Suitable power supply means for operating the actuators  62  are, of course, required but are not shown since they may be of any suitable type. 
     Operation of the embodiment of FIG.  1  and the similar but slightly modified embodiment of FIGS. 2-4 will now be described. After assembly of the torsion bar  14  with its front end engaged with the lower control arm and its rear end engaged with the associated torsion lever  32  or  58 , the torque applied to the torsion bars by the positioning of the associated torsion lever maintains the vehicle ride height at a desired value. As shown in FIG. 3, the linear actuator  62  is compressed to its shortest length which maintains the torque on the torsion bar at the lowest desired level. This results in the trim height of the vehicle being maintained at the lowest desired level so that the vehicle rides relatively close to the ground. In order to increase the trim height so that the vehicle body rides higher from the ground, the linear actuator  62  is extended as shown in FIG.  4 . This rotates the torsion lever  58  (or  32 ) clockwise as shown in the drawing, increasing the torque applied to the torsion bar  14  through its end  26  and thus increasing the supporting force of the torsion bar. The vehicle body is thus raised to a new higher trim height of the vehicle body above the ground as compared to that of the low trim height established by the arrangement of FIG.  3 . To return to the low trim height, it is only necessary to retract the linear actuator  62  to the original position shown in FIG. 3 so that the vehicle body is lowered to the low trim height position. 
     The embodiment of FIGS. 2-4 is suitable particularly for use with mechanical actuators using a screw which holds its adjusted position or hydraulic actuators which have low compressibility of the hydraulic fluid, since these devices do not comprise compressible spring-like members added in series with the suspension force provided by the torsion bars  14 . Thus, the spring rate of the torsion bars is not affected by provision of the linear actuators in the suspension assembly. However, if a pneumatic cylinder or air bag is provided as a linear actuator for moving the torsion lever, as may be the case in the embodiment of FIG. 1, the pneumatic device being a compressible member acts in series with the resilient bar  14  to provide a new combined spring rate which may adversely affect the ride quality of the associated vehicle. 
     This may be overcome by use of locks  40 , shown in FIG. 1, which include notches  46  that are engaged by protrusions or tongues  48  of the associated torsion levers  32 . The notches are arranged so that the lever engages the lower notch when the suspension is in the lower trim height position and the lever engages the upper notch when the lever  32  is in the high trim height position with its linear actuator extended. In either position, the notches and associated protrusions are so configured that they lock the levers in their adjusted positions until the lock members  40  are released by a suitable cable or other type of release mechanism, not shown. Release of the locks is thus required prior to power adjustment of the suspension between the high and low trim height positions. Otherwise, the operation of the embodiment of FIG. 1 is the same as that of the embodiments of FIGS. 2-4. The lock members lock out the pneumatic actuators  38  from acting as springs in series with the torsion bars  14  and thus return the torsion bar suspension to the originally intended spring rate. 
     Referring now to FIGS. 5-7, a third alternative embodiment of power adjustable torsion bar suspension  66  is illustrated which is similar in many respects to the embodiment of FIGS. 2-4 and wherein like numerals indicate like parts. Suspension  66  includes a longitudinal member  52  with a modified cross member  68 . The cross member includes a slot  70  in the U-shaped portion above the openings  28  and an actuator mount  72  spaced inwardly from the slot  70  on the upper side of the cross member  68 . A modified torque lever  74  has a lever arm  76  that extends up through the slot  70  when the body of the lever is received within the cross member U-shaped portion and the hexagonal opening  30  is engaged by the rear end  26  of the torsion bar  14 . The linear actuator  62  is connected with the end of lever arm  76  and extends between the lever arm and the mount  72  on the cross member. 
     When the linear actuator  62  is retracted, as shown in FIG. 6, the torsion force on the torsion bar is maintained at its minimum level so that the body of the vehicle is maintained in its low trim height position. To raise the body, the actuator  62  is extended to the position shown in FIG. 7 which rotates the torsion lever clockwise and increases the torque on the torsion bar. The vehicle body is thus raised to the high trim height position established by the change in position of the torque lever that increases the torsion bar force to a predetermined higher level. 
     FIG. 8 illustrates a fourth and somewhat different embodiment of power adjustable torsion bar suspension in accordance with the invention and generally indicated by the numeral  78 . The adjusting mechanism for suspension  78  is contained within an enclosed cross member  80 . An electric motor  82  mounted within the cross member  80  drives a worm  84  that engages a worm gear  86 . The worm gear  86  connects with a sprocket  88  that in turn engages dual chains  90 ,  92 . Chain  90  is wrapped counterclockwise around a sprocket  94  connected with a right hand torsion bar  14  and chain  92  is wrapped clockwise around a sprocket  96  connected with a left hand torsion bar  14 . 
     When the electric motor  82  is stationary, the worm gearset and the chains maintain the torsion bars  14  at a fixed torque setting to maintain the trim height position of the vehicle in a predetermined setting, such as a low height position as shown in the position of the mechanism in FIG.  8 . In order to raise the vehicle trim height, the electric motor is actuated to rotate the sprocket  88  clockwise, which in turn rotates sprocket  94  clockwise and sprocket  96  counterclockwise. The torsion bars  14  are thus both further twisted to increase their torque settings, thereby increasing the lifting force on the vehicle body and raising the body to the high trim height established by the suspension setting. Lowering of the trim height is accomplished similarly by reversing the direction of rotation of the electric motor to reduce the torsion force on the torsion bars. 
     FIGS. 9 and 10 illustrate a fifth embodiment of suspension  98  similar to that of FIG. 8 but with certain modifications. Sprockets  94  and  96  are carried on bearings  99  and engaged by the hexagonal rear ends  26  of torsion bars  14 . Electric motor  82  is connected with a transmission  100  having an angled output drive shaft  102 . The outer end of drive shaft  102  is splined and is supported by a bearing  104  mounted in the cross member  80 . The splined end of the drive shaft engages a keyed drive sprocket  106  which is connected by a chain, not shown, with the adjuster sprocket  94 . A floating drive sprocket  108  is mounted for free rotation on the drive shaft  102  and is connected by a chain, not shown, with the other adjuster sprocket  96 . An adjusting bolt  110  mounted in a protrusion  112  from the keyed drive sprocket  106  is positioned to engage an abutment  114  on the floating drive sprocket  108 . 
     Adjustment of the bolt  110  varies the relative rotational positions of the two drive sprockets  106 ,  108  and thereby varies the relative torque on the left and right side torsion bars  14  so as to obtain a proper balance or equalization of the torque forces on the torsion bars. 
     While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.