Patent Document

CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This Continuation-In-Part Application claims the benefit of Provisional Patent Application 60/477,473 filed Jun. 9, 2003 entitled STEERING WITH TRIPLE LINKAGE SUSPENSION HAVING STEERING ADJUSTED CAMBER; and Non-Provisional patent application Ser. No. 10/864,557 filed Jun. 8, 2004 entitled STEERING WITH TRIPLE LINKAGE SUSPENSION HAVING STEERING ADJUSTED CAMBER (the “Parent Application”). 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates to steering of automobiles. Specifically, this invention relates to a mechanical steering linkage which cants steered wheels during a turn to provide for evenly distributed tire distribution during high speed turns, typically encountered by racing cars making turns. In this application, mechanical steering linkage for adapting linkage to McPherson suspension and double wishbone suspension is disclosed.  
         [0003]     In four-wheel, steered vehicles, so-called double linkage or “wishbone” suspensions for the steered forward wheels of such vehicles are well known. In understanding the double linkage suspensions, conventional steering will first be described. Thereafter, the interaction of a double linkage on such conventional steering will be set forth.  
         [0004]     In conventional steering, a wheel hub is mounted for rotation in a vertical plane about and normal to a horizontally disposed steering spindle. This steering spindle is in turn connected by a vertical kingpin to a steering knuckle. Rotation of the steering spindle and the steering knuckle on the vertical kingpin occurs through a steering linkage assembly. The steering linkage assembly includes a tie rod arm fixed to and rotating with the steering spindle and a tie rod actuated by the vehicle steering wheel. Movement of the tie rod causes rotation of the tie rod arm with rotation of the steering spindle about the vertical kingpin. As the steering spindle rotates, the generally vertical plane of wheel hub rotation turns to steer the vehicle.  
         [0005]     The double linkage suspension of conventional steering is well known. Upper and lower arms (or links) are utilized to support the steering knuckle. The outer ends of such arms are typically pinned to the steering knuckle. The inner ends of such arms are attached to the vehicle. Thus, the steering knuckle can move upwardly and downwardly with respect to the vehicle body while being maintained in the generally vertical relationship relative to the vehicle. Preferably, at least one of the arms is connected by a suspension system to the vehicle. This suspension system supports the vehicle and expands and contracts to isolate and absorb shock transmitted to the steering knuckle through the wheel. Thus, shock at the wheel is prevented from reaching the vehicle by the shock absorbing suspension system.  
         [0006]     Sometimes, such double arm suspension systems are characterized by the term “wishbone”. When the arms are viewed from above towards the ground over which the vehicle travels, the arms have a generally triangular shape. The apex end of such triangularly-shaped arms is attached to the steering knuckle. The base end of such triangularly-shaped arms is attached to the vehicle. This triangular shape imparts structural rigidity to the steering suspension. The upper and lower arms of “wishbone” suspensions in modern production cars have either triangular or linear forms, depending on the space available within the body of the car. This serves as the connection to the vehicle suspension system. Open-wheel racecars typically do not have such space restraints, and therefore both the upper and lower arms assume the traditional double “wishbone” configuration.  
         [0007]     The upper and lower arms can vary in length between the steering knuckle and the vehicle. Where these arms are other than even in length, the vertical disposition of the steering knuckle and the vertical kingpin can change with up-and-down movement. Consequently, the steering spindle will vary from the horizontal. This variance from the horizontal imparts to the plane of wheel rotation the variance from the vertical. This variance of the plane of wheel rotation from the vertical is known as “camber”.  
         [0008]     It is important to note that in such systems variance of the camber is solely a function of the change of position of the steering knuckle relative to the vehicle. This change of position of the steering knuckle relative to the vehicle is in turn controlled by the suspension between the arms and the vehicle. It is especially important to note for the purposes of this disclosure that this prior art change of camber is in no way responsive to this steering of the vehicle.  
         [0009]     In the usual case, when the vehicle is steered and in the absence of dynamic forces on the arms and the suspension, the plane of rotation of the wheel remains vertical. No camber is imparted to the steered wheel. Thus, for four-wheel vehicles, the steered wheels only change in camber responsive to changing weight dynamics on the steered wheels.  
         [0010]     The camber of a conventionally steered four-wheel vehicle is to be contrasted with a two-wheel vehicle, such as a motorcycle. As is well-known, two-wheel vehicles “lean into” their turns. Thus, the camber of the wheels changes responsive to steering (and speed) of such vehicles. In the usual case, this change of camber is highly advantageous. Specifically, the tires of such two-wheel vehicles are designed with curvilinear cross-sections so that this changing camber produces an optimum footprint with respect to the road to enable a maximum grip relative to the road.  
         [0011]     The function of this grip can be easily understood.  
         [0012]     When a motorcycle travels on a straight-line path, only the vertical weight of the motorcycle on the steered and driven motorcycle wheels reacts through the tires to the motorcycle. The motorcycle wheels are conventionally, vertically loaded. When a motorcycle turns on a curved path, the vertical weight of the motorcycle on the steered and driven motorcycle wheel has added the dynamic forces generated when turning the motorcycle. Simply stated, when a motorcycle turns, centrifugal force must be overcome in turning. Thus, the wheels lean into the turn and react both to the vertical weight of the motorcycle and the centrifugal force necessary to turn the motorcycle.  
         [0013]     I have discovered that it would be highly desirable to vary the camber of the steered front and rear wheels of a four-wheel vehicle in a manner analogous to the wheels of a steered motorcycle.  
         [0014]     The Parent Application discloses a double linkage steering system for a four-wheel vehicle which changes the linkage length relative to the vehicle responsive to steering. Specifically, upon the wheel turning toward the inside of the vehicle, the tie rod of the steering system extends to turn the wheel plane of rotation toward the inside of the vehicle. At the same time, the steering pulls the upper linkage toward the vehicle causing this steering knuckle to tilt toward the vehicle. The horizontal disposition of the wheel spindle changes with the steering knuckle tilt. Camber angles of the steered wheels are altered with the plane of wheel rotation, tilting at the top toward or away from the vehicle. This same camber angle can be imparted to rear non-steered wheels. As a result, wheel camber responsive to wheel steering analogous to that of a two-wheel vehicle occurs.  
         [0015]     The steering suspension disclosed in the Parent Application is not applicable to McPherson suspensions in which a chassis-affixed strut supports the upper end of the kingpin. Motion of the top of the kingpin towards and away from the chassis is not possible.  
         [0016]     Further, the Parent Application applicable to the double wishbone suspension did not provide a chassis-connected support point that would accept the loading required by a vehicle under the dynamics of high speed turns, such as those encountered in racing.  
       SUMMARY OF THE INVENTION  
       [0017]     A McPherson strut system and double wishbone suspension system is adapted to provide adjustable camber of the suspended wheel that is responsive to steering of the vehicle. The upper member of a McPherson strut or the upper arm of a double wishbone has a slide permitting horizontally supported freedom of movement with respect to the chassis. By providing a link via the slide to the axis of steering knuckle turning, camber adjustment responsive to steering motion is attained for McPherson and double wishbone suspensions.  
         [0018]     In a vehicle steering system having a McPherson suspension, the wheel to be steered is mounted on a steering spindle so that the wheel can be steered for rotation about a generally vertical line. A steering knuckle is attached to the steering spindle. A strut assembly has an upper end attached to the vehicle chassis and a lower end supporting the steering knuckle. A lower arm of the suspension is pivoted at a first end to the steering knuckle and pivoted at a second end to the vehicle. A steering linkage assembly includes a tie rod for a movement with the vehicle steering system and a tie rod arm for rotating the steering knuckle with the steering spindle about the strut assembly. Movement of the tie rod by the vehicle steering system correspondingly moves the steering knuckle in rotation about the strut assembly to steer the vehicle. The vehicle steering system includes a slide on the upper strut support which enables movement of the strut assembly to change the camber of the strut assembly. A linkage between the vehicle steering system through the slide changes the camber of the strut assembly relative to the vehicle responsive to vehicle steering so that the camber of a wheel is changed responsive to steering.  
         [0019]     Another aspect of the invention relates to vehicle steering systems having a double wishbone suspension where a wheel to be steered is conventionally mounted to a spindle projecting from a steering knuckle for rotation about a generally vertical plane. An upper link is attached to the upper end of the steering knuckle and to a point on the vehicle chassis. A lower link is pivoted at a first end to the steering knuckle and at a second end on the vehicle chassis. The steering knuckle is pivotal about a steering axis. A steerage linkage assembly includes the tie rod for a movement with the steering system and a tie rod arm for rotating with the steering knuckle about the steering axis. This enables movement of the tie rod by the vehicle steering system and correspondingly moves the steering knuckle in rotation to steer the vehicle. A strut assembly is supported on the vehicle chassis at an upper end and pivoted to the steering knuckle at the lower end to provide the major support link to the chassis. A chassis-supported slide on the upper linkage permits movement of the linkage to change the camber of the axis about which steering knuckle rotates. A linkage between the vehicle steering system through the slide changes the camber of the steering axis relative to the vehicle responsive to vehicle steering so that the camber of a wheel is changed responsive to steering.  
         [0020]     The foregoing results in suspensions which improve car control during high speed turns and provides superior turning, braking and acceleration by maximizing the road-contacting patch of a tire. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1A  is a prior art front elevation view of a conventional double linkage vehicle suspension system;  
         [0022]      FIG. 1B  is a prior art plan view of the conventional double linkage vehicle suspension system shown in  FIG. 1A ;  
         [0023]      FIG. 2A  is a rear elevation of one wheel of the steering system of this invention illustrating the steering tie rod and upper linkage imparting vertical camber to a spindle-mounted hub on the steering system;  
         [0024]      FIG. 2B  is a rear elevation of one wheel of the steering system of this invention according to  FIG. 2A  illustrating the suspension system experiencing a vertical load, such as a bump or a dip in the road, with no steering input or lateral load imposed and no change in camber allowing the wheel to remain normal to the road, maximizing the tire&#39;s contact patch for this condition;  
         [0025]      FIG. 2C  is a rear elevation of the outboard, laden wheel of the steering system of this invention according to  FIG. 2B  illustrating the suspension system experiencing a vertical and lateral load such as a change in direction with steering tie rod turning the spindle-mounted hub by extending away from the vehicle and pulling the upper steering linkage in towards the vehicle to both increase the turn and increase the camber angle, leaning the bottom of this steered wheel to the outside of the turn;  
         [0026]      FIG. 3A  is a front elevation of one wheel of the steering system of this invention illustrating the steering tie rod and upper linkage imparting vertical camber to a spindle-mounted hub on the steering system;  
         [0027]      FIG. 3B  is a front elevation of one wheel of the steering system of this invention according to  FIG. 3A  illustrating the suspension system experiencing a vertical load, such as a bump or a dip in the road, with no steering input or lateral load imposed in this condition, and no change in camber, which allows the wheels to remain normal to the road, maximizing the tire&#39;s contact patch for this condition;  
         [0028]      FIG. 3C  is a front elevation of the outboard, laden wheel of the steering system of this invention according to  FIG. 3B  illustrating the suspension system experiencing a vertical and lateral load such as a change in direction with steering tie rod turning the spindle-mounted hub by extending away from the vehicle and pulling the upper steering linkage in towards the vehicle to both increase the turn and increase the camber angle, leaning the bottom of this steered wheel to the outside of the turn;  
         [0029]      FIG. 3D  is a perspective front elevation similar to  FIG. 3C  changing the angle of view of the wheel club to illustrate steered deflection and changed camber;  
         [0030]      FIG. 3E  is a rear elevation of the inboard, unladen wheel of the steering system of this invention according to  FIG. 3B  illustrating the suspension system experiencing a vertical and lateral load such as a change in direction with the steering tie rod turning the spindle-mounted hub by pulling it towards the vehicle and extending the upper steering linkage away from the vehicle to both increase the turn and increase the camber angle, leaning the bottom of this steered wheel to the outside of the turn;  
         [0031]      FIG. 4  is a plan view of the invention shown in  FIGS. 2A-2D  and  3 A- 3 E;  
         [0032]      FIG. 5A  is an elevation of the front left and right suspensions according to  FIG. 3C  and  FIG. 3E  illustrating the suspension system experiencing a change in direction to the right with the suspension system leaning the tires into the corner, much like a motorcycle;  
         [0033]      FIG. 5B  is an elevation of the rear elevation of the rear left and right suspensions illustrating the suspension system experiencing a change in direction to the right with the suspension system leaning the tires into the corner, much like a motorcycle;  
         [0034]      FIG. 5C  is a rear view of the front and rear suspensions illustrating the suspension system experiencing a change in direction to the right with the front and rear suspension systems working in tandem to lean the tires into the corner, much like a motorcycle;  
         [0035]      FIG. 6A  is a prior art front elevation diagram of a conventional double linkage vehicle suspension system and plan views of the tires&#39; contact patches, showing the vehicle at rest and the contact patches displaying the maximum surface area;  
         [0036]      FIG. 6B  is a prior art front elevation diagram of a conventional double linkage vehicle suspension system and plan views of the tires&#39; contact patches according to  FIG. 6A  showing the vehicle under vertical loading, and the contact patches displaying a compromised tire contact patch due to the negative camber built into the prior art design;  
         [0037]      FIG. 6C  is a prior art front elevation diagram of a conventional double linkage vehicle suspension system and plan views of the tires&#39; contact patches according to  FIG. 6A  showing the vehicle under vertical loading and lateral loading, and the laden wheel displaying a maximum contact patch due to the negative camber and the bending and distortion of the linkages and tire caused by lateral forces, while the unladen wheel is displaying a compromised tire contact patch due to the negative camber built into the prior art design;  
         [0038]      FIG. 6D  is a front elevation suspension diagram of this invention and plan views of the tires&#39; contact patches, showing the vehicle at rest and the contact patches displaying the maximum surface area;  
         [0039]      FIG. 6E  is a front elevation suspension diagram of this invention and plan views of the tires&#39; contact patches according to  FIG. 6D  showing the vehicle under vertical loading, and the contact patches displaying no change in camber, thus providing the maximum contact patch;  
         [0040]      FIG. 6F  is a front elevation suspension diagram of this invention and plan views of the tires&#39; contact patches according to  FIG. 6D  showing the vehicle under vertical loading and lateral loading, and both wheels displaying maximum contact patches due to the cambers favorably generated to counteract any bending and distortion of the linkages and tire caused by lateral forces;  
         [0041]      FIG. 7A  is a front elevation of a McPherson suspension improved with a horizontal slide on the strut for permitting wheel camber change responsive to steering;  
         [0042]      FIG. 7B  is a top plan view of the McPherson suspension of  FIG. 7A  illustrating the construction of the slide that is part of the camber adjustment system;  
         [0043]      FIG. 8  is a front elevation of a double wishbone suspension improved with a horizontal slide supported from the chassis and affixed to the upper strut for permitting wheel camber change responsive to linkage extension during steering;  
         [0044]      FIG. 9A  is a plan view of the embodiment of the present invention suitable for use on vehicles on which the steering linkage is in front of the vehicle, the top of the figure being the front of the vehicle;  
         [0045]      FIG. 9B  is a front elevation of the embodiment shown in  FIG. 9A ;  
         [0046]      FIG. 9C  is a front elevation similar to  FIG. 9B  but shows the wheel turning to the right relative to the vehicle; and  
         [0047]      FIG. 9D  is a front elevation similar to  FIG. 9C  but shows the wheel turning to the left. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0048]     Referring to prior art  FIGS. 1A and 1B , wheel  14  is shown rotating about spindle  16  at a hub  15 . Spindle  16  extends from steering knuckle  18  which is pivotable about a kingpin  20  for steering the vehicle. Spindle  16  has upper arm  26  linked to lower arm  28 . Tie rod  32  is responsive to the vehicle&#39;s steering system and moves towards and away from vehicle  10 . Since spindle  16  is substantially horizontal, wheel  14  rotates in a generally vertical plane.  
         [0049]     Referring to  FIG. 1A , upper arm  26  and lower arm  28  can be seen extending between steering knuckle  18  and vehicle  10 . The arms  26 ,  28  have essentially the same length. As is shown in  FIG. 1B , lower arm  28  is triangular in plan with the apex end of the arm pinned to the lower portion of the steering knuckle  18 . Suspension  30  interconnects lower arm  28  and vehicle  10 . It provides for the support of this steered wheel  14  relative to the vehicle  10 .  
         [0050]     In the system of  FIGS. 1A and 1B , the camber of wheel  14  is essentially constant with up-and-down movement of steering knuckle  18 . That is to say, the camber can only be changed substantially by changing the lengths of the upper arm  26  and lower arm  28  with respect to one another. Further, camber will not change in response to the steering of vehicle  10 .  
         [0051]     Addressing the present invention and referring to  FIGS. 2A and 3A , wheel  14  has been removed, exposing hub  15  on spindle  16 , which is shown in phantom. Steering mechanism  40  of vehicle  10  is shown in the form of star wheel  40 . Star wheel  40  has two linkages attached thereto. A tie rod  24  is connected to the lower portion of the star wheel for turning spindle  15  conventionally about vertical kingpin  20 , and conventional steering of hub  15  (and spindle  16 ) occurs. Further, an upper link  26  has its ends attached to an upper portion of star wheel  40  and to steering knuckle  18 . Upon pivotal movement of star wheel  40  in the clockwise ( FIG. 2A  front elevation) direction, tie rod  24  is moved to the left as seen in  FIG. 2A  and hub  15  will turn towards the vehicle  10 . At the same time, upper link  26  is pulled toward vehicle  10  and pulls knuckle  18  with it, which leans the top portion of the knuckle towards the vehicle (not shown in this view). This causes the bottom of hub  15  to move away from vehicle  10 . The result is a change in the camber of hub  15 . These movements can be observed in  FIGS. 2C, 3C  and  3 D.  
         [0052]     Wide variations in the proportional movement and direction of the respective linkages can occur. For example, the length of the lower link  28  can be very responsive to the movement of tie rod  24 . Further, the lever arm of star wheel  40  for both tie rod  24  and upper link  26  can be altered to virtually any desired ratio to vary the proportional relationship between the steering and camber adjusting movements. Additionally, as shown here, variation of the camber of the steered wheel is responsive to movement of the steering mechanism. This same mechanism for variation of camber can also be applied to the driven rear wheels of a four-wheel vehicle. This is illustrated schematically in  FIGS. 5A, 5B  and  5 C, it being noted that although changes in camber are shown, a linkage between the steered wheels and the rear, non-steered wheels is omitted. The reader will understand that virtually any linkage will do. For example, by placing a star wheel  40  adjacent the non-steered wheels and linking to the front star wheel  40 , camber can be imparted to the rear steered wheels. Similarly, servos and the like can impart the desired camber. As can be seen in  FIGS. 5A, 5B  and  5 C, the respective rear wheels are labeled  14   r , and upper link  26   r  and lower link  28   r , in the drawings.  
         [0053]     Further, the steering mechanism here shown in the form of star wheel  40  is exemplary only. All kinds of steering mechanisms can respond to the linkage here shown. For example, rack and pinion steering could as well be used. These and other variations of this invention can occur.  
         [0054]     Referring to the prior art  FIG. 6A , wheel assembly T 1  is shown to be connected to vehicle  10  by linkage assembly L 1 . Likewise, wheel assembly T 2  is shown to be connected to vehicle  10  by linkage assembly L 2 . Vehicle  10  is shown to be at rest or traveling at a constant velocity with no vertical or lateral loading. Contact patches P 1  and P 2  are the surface areas of tires T 1  and T 2  respectively, making contact with road surface G as seen from below, as if road surface G were transparent. T 1  and T 2  are shown to be normal to the road surface, that is, zero camber, and contact patches P 1  and P 2  are shown to have the maximum surface area making contact to road surface G.  
         [0055]     Referring to the prior art  FIG. 6B , wheel assembly T 1  is shown to be connected to vehicle  10  by linkage assembly L 1 . Likewise, wheel assembly T 2  is shown to be connected to vehicle  10  by linkage assembly L 2 . Vehicle  10  is shown to be experiencing a vertical load. Contact patches P 1  and P 2  are the surface areas of tires T 1  and T 2  respectively, making contact with road surface G as seen from below, as if road surface G were transparent. T 1  and T 2  are shown to be imparting negative camber, consequently altering contact patches P 1  and P 2  to triangular-shaped surface areas making contact to road surface G, reducing the total surface area and thus providing less grip.  
         [0056]     Referring to the prior art  FIG. 6C , wheel assembly T 1  is shown to be connected to vehicle  10  by linkage assembly L 1 . Likewise, wheel assembly T 2  is shown to be connected to vehicle  10  by linkage assembly L 2 . Vehicle  10  is shown to be experiencing a lateral load to the left. Contact patches P 1  and P 2  are the surface areas of tires T 1  and T 2  respectively, making contact with road surface G as seen from below, as if road surface G were transparent. Tire T 1  is laterally loaded and is shown to be imparting negative camber, and because of the distortions of tire T 1 &#39;s cross-section and bending of linkage L 1  caused by the lateral load and the subsequent rolling of the vehicle  10  by angle R 0 , contact patch P 1  has a rectangular-shaped surface area making contact to road surface G, maximizing the grip for tire assembly T 1 . Tire T 2  is unloaded and is shown to be imparting negative camber, altering contact patch P 2  to a triangular-shaped surface area making contact to road surface G, reducing the maximum grip for tire assembly T 2 .  
         [0057]     Referring to  FIG. 6D  of this invention, wheel assembly T 1  is shown to be connected to vehicle  10  by linkage assembly L 1 . Likewise, wheel assembly T 2  is shown to be connected to vehicle  10  by linkage assembly L 2 . Vehicle  10  is shown to be at rest or traveling at a constant velocity with no vertical or lateral loading. Contact patches P 1  and P 2  are the surface areas of tires T 1  and T 2  respectively, making contact with road surface G as seen from below, as if road surface G were transparent. T 1  and T 2  are shown to be normal to the road surface, that is, zero camber, and contact patches P 1  and P 2  are shown to have the maximum surface area making contact to road surface G.  
         [0058]     Referring to  FIG. 6E  of this invention, wheel assembly T 1  is shown to be connected to vehicle  10  by linkage assembly L 1 . Likewise, wheel assembly T 2  is shown to be connected to vehicle  10  by linkage assembly L 2 . Vehicle  10  is shown to be experiencing a vertical load. Contact patches P 1  and P 2  are the surface areas of tires T 1  and T 2  respectively, making contact with road surface G as seen from below, as if road surface G were transparent. T 1  and T 2  are shown to be normal to the road surface, that is, zero camber, and therefore contact patches P 1  and P 2  are unaffected and are shown to have the maximum surface area making contact to road surface G, providing the maximum possible grip.  
         [0059]     Referring to  FIG. 6F  of this invention, wheel assembly T 1  is shown to be connected to vehicle  10  by linkage assembly L 1 . Likewise, wheel assembly T 2  is shown to be connected to vehicle  10  by linkage assembly L 2 . Vehicle  10  is shown to be experiencing a lateral load to the left. Contact patches P 1  and P 2  are the surface areas of tires T 1  and T 2  respectively, making contact with road surface G as seen from below, as if road surface G were transparent. Tire T 1  is laterally loaded and is shown to be imparting negative camber, and because of the distortions of tire T 1 &#39;s cross-section and bending of linkage L 1  caused by the lateral load and the subsequent rolling of the vehicle  10  by angle R 0 , consequently alters contact patch P 1  to a rectangular-shaped surface area making contact to road surface G, maximizing the grip for tire assembly T 1 . T 2  is unloaded and is shown to be imparting positive camber, and because of the distortions of tire T 2 &#39;s cross-section and bending of linkage L 2  caused by the lateral load and the subsequent rolling of the vehicle  10  by angle R 0 , consequently alters contact patch P 1  to a rectangular-shaped surface area making contact to road surface G, maximizing the grip for tire assembly T 2 .  
         [0060]     The change of camber of the wheels effectively changes the stability of a car to which this system is attached. When the tire is standing perpendicular or normal to the road surface, it has 0° of camber. This is shown in  FIG. 6A . When the top of the tire is tilted in towards the car, it is said to have negative camber. This is shown in  FIG. 6B . When the top of the tire tilts away from the center of the car, it has positive camber. This is shown on T 2  of  FIG. 6F . When the tire experiences lateral loading, the tire&#39;s coefficient of friction, or CF, varies with the change in camber, because of the cross-sectional distortion it experiences. See  FIG. 6F . For the outboard loaded or laden tire, the CF increases from 0° camber to negative camber, and decreases from zero to positive camber. When the tire is subjected to lateral loading with 0° camber, the contact patch distorts from the optimum surface area because of the deflection and bending of the suspension components and the distortion of the tire&#39;s cross-section itself. Thus creating negative camber corrects the contact patch&#39;s distortion, and restores the patch to optimum surface area, only on the laterally loaded tire. This is the reason for the increase in the CF with negative camber. Note this change in the CF relative to camber only applies to lateral loading and not vertical loading conditions. An optimum operation of the contact patch is shown in  FIG. 6F .  
         [0061]     On vertical loading conditions, the tires must remain normal to the road surface, and any degree of camber is unfavorable, as it reduces the contact patch of the tires, thus reducing the grip capabilities of the tire. Specifically, each tire—either steered or non-steered—has a “contact patch” relative to the road. The contact patch is that portion of the tire that makes contact with the road. Moreover, most racing tires have a rectilinear cross-section at their periphery and point of contact to the road. Accordingly, and with a tire of rectilinear section, even a slight change of camber of the tire will shift the contact patch to the side of the tire and away from the center of the tire. The present invention&#39;s ability to favorably change the camber angles depending on the tires&#39; loading condition maximizes the amount of grip the tires can generate. Improved steering, stability and, most important, maximum grip will result.  
         [0062]     The combined steering/camber adjustment system described above is particularly suitable for cars on which the steering linkage is aft (as viewed in the travel direction of the vehicle) of the wheel suspension. It makes use of space available in front of the suspension for placing the camber adjustment mechanism. When the steering linkage is in front of the wheel suspension and axle or spindle about which the wheel rotates, the embodiments of the invention shown and described in connection with  FIGS. 9A-9D  are particularly suitable.  
         [0063]      FIG. 7A  illustrates a steered wheel  14  with a McPherson suspension  102 . The wheel is mounted on a spindle  16  carried by a knuckle  104  with a lower extension  106  that is pivotally connected to a lower arm  108  which generally extends inwardly (towards the vehicle) and has an inner end  110  that is pivotally connected to a chassis  112  of the vehicle. The chassis includes a support wing  114  that is disposed some distance above the axis of wheel  14  and includes an aperture  116  through which a plunger  118  of a strut  120  (that includes a shock absorber) extends. A lower end  122  of the strut is conventionally fixed to knuckle  104  via a bracket  124  or the like. A conventional coil spring  126  surrounds the strut, and its ends are suitably supported by chassis wing  114  and knuckle bracket  124 .  
         [0064]     A head  128  of strut plunger  118  is located above the upper surface of chassis wing  114  and is pivotally connected to a camber adjustment link  130  of a camber adjusting system  132  constructed in accordance with the present invention. A linear slide bearing  134 , shown in more detail in  FIG. 7B , includes a mounting plate  80  that is rigidly secured, e.g. bolted, to the chassis wing so that an elongated slot  83  overlies aperture  116  in the chassis wing. A slide plate  85  of the bearing is movable along elongated tracks, such as grooves,  81 ,  82  in the mounting plate, and linear bearing units  86 ,  87  are interposed between the mounting and slide plates so that the latter can linearly move relative to the former in a direction parallel to slot  83 . Slide plate  85  includes a tubular section  136  through which plunger  118  of strut assembly  120  extends past plates  80 ,  83  and aperture  116  in chassis wing  114 . A linear bearing suitable for use with the present invention can be obtained from HIWIN Corp. of Mount Prospect, Ill. 60056 (LG Series).  
         [0065]     Linear slide bearing  134  is secured, e.g. bolted, to chassis wing  114 , and tracks  81 ,  82  of the mounting plate are oriented perpendicular to the horizontal camber pivot or tilt axis  127  between lower extension  106  of knuckle  104  and lower arm  108  so that, by moving strut head  128  to the left or the right, as indicated by the arrow in  FIG. 7A , the wheel  14  is tilted about the camber pivot axis to thereby adjust the camber of the wheel positively or negatively, depending on the direction of movement.  
         [0066]     To induce such pivotal motions of the knuckle and change the camber, the inward end of link  130  is pivotally connected to an actuator  138  that is used for steering wheel  14 , as is further described below. Actuator  138  pivotally moves about a pivot point  99  and includes arms  100  that extend in both directions from pivot point  99 . One of the arms is pivotally connected to link  130 .  
         [0067]     The other arm  100  is pivotally connected to a tie rod  140  that is part of a steering linkage  142  for the wheel. The other end of the tie rod is conventionally connected to knuckle  104  so that inboard or outboard movement of the tie rod, as indicated by the arrows immediately above it, causes wheel  14  to turn in one direction or the other.  
         [0068]     In operation, turning of steering actuator  138 , for example in a clockwise direction, pushes camber adjustment link  130  in an outboard direction (towards wheel  14 ) while it pulls steering linkage  142  in an inboard direction. This results in turning wheel  14  about a vertical turning axis (not shown in  FIG. 7A ) while it tilts wheel  14  about tilt axis  127  and gives the wheel the desired camber. Moreover, the greater the degree of steering, i.e. the more the wheel is turned, the greater is the camber because the camber is established as a function of the degree of turning since actuator  138  proportionally moves link  130  of the camber adjusting system  132  and tie rod  140  of the steering linkage  142 . As actuator  138  is turned, camber adjusting link  130  linearly moves the top of strut  120  as guided by linear slide bearing  134 . The proportional relationship between the turning of the wheel for steering and tilting it to give it a camber can be changed, for example by providing actuator arms with multiple holes over its length, as shown in  FIG. 2A  for star wheel  40 , and changing the attachment points for the tie rod  140  and/or link  130 .  
         [0069]     Further, depending on whether actuator  138  rotates in the clockwise or counterclockwise direction, wheel  14  is turned to the right or the left by the desired degree, while both wheels  14  (only one is shown in  FIG. 7A ) are tilted to establish the desired camber proportionally to the degree by which the wheel is turned.  
         [0070]      FIG. 8  shows another embodiment of the present invention applied to a wishbone suspension  144  for steering wheel  14 . It has a steering knuckle  146  from which spindle  16  for wheel  14  extends and includes upwardly and downwardly extending legs  148 ,  150 . The lower leg  150  is pivotally connected at  152  to an outboard end of a lower arm  154 , the inboard end of which is pivotally connected to a chassis  156 , as is well known to those skilled in the art. A strut assembly including a shock absorber and a helical compression spring is conventionally attached to the lower leg  150  of the wishbone connection and an upper wing portion of chassis  156 .  
         [0071]     The upper leg  148  of knuckle  146  is pivotally connected to a link  160  of a camber adjustment system  162 . The link defines an assembly made up of first and second link sections  160   a ,  160   b  which are interconnected by a pivot connection  164  that is supported by a linear slide assembly  166 . In a preferred embodiment of the invention, the outer link section  160   b  is formed by an arm of the upper wishbone.  
         [0072]     The inboard end of link section  160   a  is pivotally attached to a pivotable actuator  168  which has arms  170  extending in opposite directions.  
         [0073]     When actuator  168  is pivoted about its axis, it pushes or pulls link  160 , depending on the direction of rotation, thereby pivoting knuckle  146  about camber pivot  152 , which tilts wheel  14  relative to the vertical and imparts a camber to the wheel.  
         [0074]     A tie rod  172  of a steering mechanism  174  has its inboard end pivotally attached to the other arm  170  of actuator  168 . The outboard end of the tie rod is pivotally attached to a tie rod arm  176  of knuckle  146  so that, upon pivoting of actuator  168 , the tie rod is pushed outwardly or pulled inwardly and the wheel is turned or steered accordingly about a vertical steering axis  178 .  
         [0075]     In operation, when turning is desired, the steering system of the vehicle will pivotally move actuator  168  in one direction or the other. This results in an outward push on camber adjustment link  160  and an inward pull of steering tie rod  172  in proportional amounts. The outward push (or inward pull when the actuator is turned in the other direction) of link  160  causes knuckle  146 , and therewith wheel  14 , to be tilted about camber pivot  152  relative to the vertical to establish the desired wheel camber in the desired direction. Thus, the more wheel  14  is turned, the greater is the camber that is imparted to the wheel, and vice versa.  
         [0076]      FIG. 8  only shows one steered wheel. The combined steering mechanism and camber adjustment system are applied equally to the other steered wheel (not shown in  FIG. 8 ).  
         [0077]     Moreover, the combined steering and tilting mechanism of the present invention can also be adapted to cause camber in the non-steered, e.g. rear, wheels (not shown in  FIGS. 7A and 8 ) should that be desirable.  
         [0078]     In many production cars, the steering mechanism, and in particular the tie rod which connects to the knuckle for steering the wheel about a vertical steering axis, is located behind the wheel in the driving direction of the car. The embodiments of the invention described above are principally useful for such arrangements of the steering mechanism. However, when the steering mechanism, and in particular the steering tie rod, is located in front of the wheel, that is, in front of the wheel axle (spindle) and its suspension, the geometric configuration of the available space makes it difficult to mount the link for activating the camber system at the ends of opposite arms of the pivotal actuator or star wheel as described above.  FIGS. 9A-9D  show embodiments of the invention best suited for such applications.  
         [0079]     Referring to  FIGS. 9A-9D , in another embodiment of the present invention, the tie rod  180  of a steering mechanism  182  and the link  184  of a camber adjustment system  186  have their outboard ends coupled to knuckle  188  as described above. However, both the tie rod and the link are located forward of the wheel. In this configuration, the inboard ends of the tie rod and the link are attached to the same arm  190  of a pivoting actuator  192  due to space limitations. The steering mechanism tie rod is attached to arm  190  at a point radially further away from pivot axis  194  than the point where the inboard end of camber link  184  is attached to the arm. As a result, when the actuator  192  is pivoted, steering tie rod  180  and camber link  186  again move proportionally over different distances to steer the wheel and tilt it to establish a camber that is proportional to the extent to which the wheel is turned for steering. It should be pointed out that for ease of illustration the pivoting actuator  192  is shown in  FIGS. 9A-9D  as having a pivot axis  194  that is vertical so that the actuator pivots in a horizontal plane. This is optional and may be replaced by an actuator which pivots about a horizontal axis (as is shown in  FIGS. 7A and 8 , for example), depending on the available space and the configuration of other parts in the vicinity of the wheels, the steering mechanism and, when applicable, the engine of the car.

Technology Category: b