Abstract:
An optical wheel alignment apparatus intended for race cars and other high performance road vehicles which provides an extremely accurate, low-cost, light-weight, portable and non-electrical method for toe and camber alignments even in space limited and hostile environments such as race car pit areas. Further, the apparatus is simple to operate, requires less that five-minutes set-up time and provides repeatable accuracy up to two minutes of a degree toe and 1/8&#34; camber without the aid of computer control.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an optical wheel alignment apparatus, and more particularly to a portable wheel alignment system and method for high performance race car vehicles where rapid, highly accurate and cost effective alignments of camber and toe can be performed at a race site. 
     2. Description of Related Art 
     Generally, state-of-the-art wheel alignment has become computer controlled with laser and, more recently, microwave technology for alignment measurements. These apparatus are intended for shop use, are large systems with computer type screens and keyboards. Typically, a plurality of automobile manufacturer designs and model specifications will be already loaded into the computer memory. Information such as manufacturer settings of caster, steering axis inclination, chassis center point and recommended camber and toe will be readily available to the operator for the specific automobile on the alignment rack. These apparatus are designed for consumer automobile and truck wheel alignments, not for high-performance race cars such as formula, sport and Indy type cars. 
     In today&#39;s technology, when mechanics for high-performance race cars have needed wheel alignment apparatus they have tried modifying consumer oriented wheel alignment apparatus such as those discussed prior. What could not be modified out of these alignment apparatus was the bulkiness and awkwardness of these computer oriented alignment tools with display panels and interconnecting cables. Add to this disadvantage the fact that set-up times for these apparatus can be unacceptably long and the fact that the computer has to be programmed for each customized race car before the alignment can be performed, and it becomes evident that simply modifying today technology wheel alignment apparatus for use in the race car environment is not the answer. 
     What has been needed is a simple, inexpensive, light weight, and perhaps even portable, wheel alignment apparatus that will immediately work for any customized formula, sports, or Indy, type race car without the need for sophisticated computer hardware and software with viewing screen, bulky interconnecting cables and heavy housing assembly. 
     This invention provides such an apparatus for checking, and adjusting wheel alignment on high performance race cars. 
     SUMMARY OF THE INVENTION 
     This invention is directed to a race car wheel alignment apparatus wherein the apparatus utilizes a telescope and target much like a surveyor&#39;s theodolite to simultaneously measure toe and camber and allow precise adjustments, (repeatable to within two minutes of a degree), without the need for computer interaction. Furthermore, this wheel alignment apparatus is designed to operate in the hostile, and what would be for above mentioned reference art impractical, race crew pit areas during a race when emergency wheel alignment may be required. 
     The apparatus provides one-half inch thick aluminum, or similar light weight material, plates, (called rocker plates), which bolt to the hubs of one axle in place of the wheels. A telescope, with cross hairs visible through the viewer end, is clamped onto one of the rocker plates. A target, with camber and toe calibration markings, is attached to the opposite rocker plate. In this embodiment of the invention, by viewing through the telescope, the cross hairs appear superimposed on the target which simultaneously indicates toe and camber measurements of the wheel hub to which the telescope is mounted. The toe and camber settings can then be adjusted, on most race cars, by tie rod or toe control rod end adjustments while instantly observing the results through the telescope viewer without the necessity of further measuring or fiddling with other alignment tools or apparatus. Any effect that a camber change may have on the toe setting, or visa versa, will be instantly observable without the need for removing one alignment apparatus to be replaced with a second alignment apparatus. 
     The wheel alignment apparatus of this invention is capable of resolving 1 minute, (1/60th of a degree or 0.003&#34;), at a wheel hub representing a tire and is repeatable to 2 minutes. One reason this wheel alignment apparatus is more accurate and repeatable than most reference art is because this invention eliminates wheel run out, (the wheels are not attached to the hub during alignment), and parallax is eliminated as a source of error. 
     The rocker plates are trued into a perfectly vertical position by use of an ultra sensitive level, which is built into the telescope base, and an adjustment tool. Once the rocker plates, attached to both wheel hubs, have been vertically trued the telescope is mounted to one rocker plate and the target plate is mounted to the other rocker plate. The telescope and the target plate are indexed to their respective rocker plates, both fore and aft, by roll pins in their clamp assemblies. 
     Calibration of the telescope is accomplished with a calibrator plate which clamps onto the telescope and allows the telescope to be rotated ±90° about the horizontal line of sight. If the telescope is precisely 90° to the plate in all directions, that line of sight will fall on the same point on the target without any wobble while the telescope is being rotated. Any variation in the line of sight location on the target during calibration can be adjusted out by use of toe and camber adjustments screws provided on the telescope body. 
     Since each wheel is aligned independently, the optical wheel alignment apparatus doesn&#39;t care if two-wheel or four-wheel alignment is to be performed. 
     Other features and advantages of the present invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the optical wheel alignment apparatus which depicts the two rocker plates mounted to wheel hubs with the telescope mounted to one rocker plate and the target plate mounted to the opposite rocker plate. 
     FIG. 2 is an exploded perspective view at 2 in FIG. 1 which depicts the telescope mounting assembly with integral precision level. 
     FIG. 2a is a partial cross-sectional view of the telescope mounting assembly viewed at lines 3--3 in FIG. 2. 
     FIG. 3 is perspective drawing of the telescope assembly of the invention with a partial cutaway section for viewing internal components. 
     FIG. 4 is a perspective view of the information obtained by the operator from the TOE and CAMBER target plate when viewed through the telescope. 
     FIG. 4a is a perspective view of the TOE and CAMBER target plate as it actually appears on a frontal view, before being reversed by the mirror in the telescope. 
     FIG. 4b is a perspective view of what an operator may see through the viewer of the telescope during an actual wheel alignment check. 
     FIG. 5 is a perspective view of a typical alignment configuration, when viewed from the front of the race car, which depicts how the camber hairline would move on the target relative to camber adjustments of the wheel hub. 
     FIG. 6 is a perspective view of a typical alignment configuration, when viewed from above the race car, which depicts how the toe hairline would move on the target relative to toe adjustments of the wheel hub. 
     FIG. 7 is a perspective view of the telescope assembly depicting its orientation when rotated ±90° during calibration, with the toe and camber calibration screws visible on the housing of the telescope. 
     FIG. 8 is a perspective via typical optical wheel alignment apparatus set-up with a partial cutaway of the telescope assembly housing to depict the viewer&#39;s sight path. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention includes a method and apparatus for wheel alignment on race cars which is compact, light weight, inexpensive, and simple to operate. 
     Referring now to the drawings, and particularly to FIG. 1, there is shown a typical set-up of the optical wheel alignment apparatus 10 wherein the front wheels of the race car have been removed from the wheel hubs 14 and replaced by the rocker plates 11. The rocker plates 11 with rocker stops 13 have then been raised and the surface plates 12 inserted so that the rocker plates 11 can be vertically trued and leveled through minor adjustments of the rocker plates orientation. The rocker plates 11 extend far enough above the chassis of the race car to provide a clear line of sight 45 between the two opposite rocker plates 11. In FIG. 1, the telescope assembly mounting base 20, the telescope assembly 40 and the target plate assembly 30 with toe and camber calibration chart 31 have been installed as would be the case during a wheel alignment procedure after the apparatus had been calibrated, a procedure described later. 
     Referring now to FIGS. 2 and 2a, the elements of the telescope assembly mounting base 20 are detailed. In the preferred embodiment, the telescope assembly mounting base 20 comprises at least one roll pin 21 to ensure repeatability of precision alignment of the mounting base 20, a highly precise bubble type level 23 with two windows 22, for viewing the level, machined into the top and outer side of the mounting base 20. The telescope assembly mounting base 20 further includes a thumb screw 24 for securing the mounting base 20 to one of the rocker plates 11. A final element of the telescope assembly mounting base comprises a countersunk and captive set screw 25 which secures the telescope assembly 40 into a machined cradle of the mounting base 20 that fits the outside dimensions of the telescope housing 41. The telescope assembly 40 and mounting base 20 are assembled at the factory and may be treated as a single assembly. 
     Turning now to the telescope assembly 40 and FIG. 3, the telescope housing 41 has a proximal end with a viewers window 42, (also referred to as the eye piece of the telescope assembly 40), and a distal end which is closed off 43. Inside the telescope housing 41, near the distal end of said housing a mirror 46 is mounted at such an angle as to reflect the image in the line of sight 45 to the viewer&#39;s window 42. The telescope 47 has superimposed upon its line of sight 45 a pair of crossing hairlines 48 intersecting at the precise center of the viewing window 42. It is these hairlines that the mechanic sees superimposed on the target chart 31 image that identifies the amount of toe and camber present during wheel alignment. Not shown in FIG. 3 are two set screws in the telescope housing 41 side wall which allow precision setting of the toe and camber lens during telescope calibration, discussed later. These set screws 50 and 51 are visible in FIG. 7. 
     FIG. 4 is a rendition of what the toe and camber alignment chart 31 will look like to the mechanic as viewed from the proximal end 42 of the telescope assembly 40, except that the superimposed hairlines from the mirror 46 have been omitted. In reality, the toe and camber alignment chart 31&#39; shown in FIG. 4a is what the mechanic will see if viewing the chart directly. This discrepancy of the view is necessary since the image of the toe and camber alignment chart 31&#39; attached to the target plate 30 is reversed, (in fact, turned up side down), by the mirror 46 in the telescope housing 41. FIG. 4b shows what the mechanic will see when viewing target 31 through telescope assembly 40 with the crosshairs superimposed. 
     Looking now at FIG. 5 a typical wheel alignment configuration is shown for the invention. In this rendition the viewer is looking at the front of the race car with the telescope assembly 40 attached to the rocker plate 11 that replaces the left wheel of the race car and the target plate assembly 30 is mounted to the rocker plate 11 that replaces the right wheel of the race car. In this rendition variations in camber settings are depicted. With no camber set into the left wheel hub 14, the line of sight 45 would place the horizontal cross hair at the center of the toe and camber alignment chart 31&#39; indicated as line of sight 45 in FIG. 5. If positive camber of the left wheel hub 14 existed, the rocker plate 11 would be moved at the top in the direction of the right arrow in FIG. 5. This would have the effect of moving the horizontal cross hair towards the line of sight 45 + , (or upward on the toe and camber alignment chart) indicating to the mechanic viewing through the telescope assembly at 42 a positive camber. A negative camber in the left wheel hub 14 would have the effect of moving the top of the left rocker plate 11 towards the left arrow on FIG. 5 and thus the horizontal cross hair on the toe and camber alignment chart toward the 45-line of sight thereby indicating a negative camber to the mechanic viewing at 42. When the telescope assembly 40 and target plate assembly 30 are moved to the opposite rocker plates 11, the same camber setting will produce the same resultant views to the mechanic at the telescope assembly 40 viewing end 42. Now viewing FIG. 6 we see a rendition of a typical optical wheel alignment configuration of the invention as would be seen from directly above the race car looking down on the front axle. Here again the telescope assembly 40 is mounted to the rocker plate 11 that is mounted to the left wheel hub 14 replacing the left wheel of the race car. In this rendition variations in wheel toe settings are depicted. With no toe set into the left wheel hub 14, the line of sight 45 would place the vertical cross hair at the lateral center of the toe and camber alignment chart 31&#39; indicated as line of sight 45 in FIG. 6. If toe-in of the left wheel hub 14 existed, the rocker plate 11 would be rotated in the direction of the left arrow in FIG. 6. This would have the effect of moving the vertical cross hair towards the line of sight 45 in , (or towards the right on the toe and camber alignment chart 31&#39;) indicating to the mechanic viewing through the telescope assembly at 42 a toe-in wheel condition. A toe-out condition in the left wheel hub 14 would have the effect of rotating the left rocker plate 11 towards the right arrow on FIG. 6 and thus the vertical cross hair superimposed on the toe and camber alignment chart 31&#39; toward the 45 out  line of sight thereby indicating a toe-out wheel condition to the mechanic viewing at 42. When the telescope assembly 40 and target plate assembly 30 are moved to the opposite rocker plates 11, the same toe-in or toe-out wheel condition will produce the same resultant views to the mechanic at the telescope assembly 40 viewing end 42 with one exception noted on the target. That exception is that vertical cross hairs superimposed on target 11 to the rear of target 11&#39;s vertical centerline, represents toe-in in all cases (left or right wheels). 
     Calibration 
     Any alignment apparatus requires that the equipment to be used in the alignment procedure be calibrated to ensure compliance to operation within the design parameters of the apparatus. The optical wheel alignment apparatus of this invention includes calibration tools and procedures to ensure design parameters are met. The telescope calibration plate must be manufactured with a width (left to right) and index slots placed so as to produce an identical line of sight at the mirror surface regardless of the -90° or +90° installation. 
     Referring now to FIGS. 1 and 2, the following set-up and calibration procedures are incorporated as part of the invention. The set-up procedures in this paragraph must be performed before alignment of any car or calibration of the instrument. Once the front axle wheels have been replaced with rocker plates 11 mounted to the respective wheel hubs 14 and the surface plates 12 and rocker stops 13 are in place, an elastic device (spring or bungee) is used to only slightly apply the car&#39;s brakes. The rocker plates 11 are radiused on the bottom surface to accommodate slight forward and backward motion. While viewing the bubble level 23 on the telescope assembly mounting base 20, a screwdriver or lever is inserted between the rocker stop 13 and the surface plate 12. This is used to lift and slightly rotate the rocker plate until it is perfectly true vertically as indicated by the precision bubble level 23. After one rocker plate is true, remove the telescope assembly mounting base and install it on the opposite rocker plate 11. Repeat the above procedures for the second rocker plate 11. Recheck the first rocker plate. When both rocker plates are true and level the telescope assembly can be calibrated. 
     FIG. 7 depicts a rendition of the invention while the telescope assembly is being calibrated. To calibrate the telescope assembly 40 and assembly mounting base 20, the telescope calibration plate 56 is installed on the rocker plate 11 in the same vertical plane as the telescope assembly 40 and mounting base 20 during alignment procedures. The telescope assembly mounting base 20, with telescope assembly 40 attached, is then mounted in a 90° position from its normal wheel alignment position on the rocker plate 11 and a first sighting of the location of the cross hairs superimposed on the toe and camber alignment chart 31 are recorded by the mechanic. The telescope assembly and mounting base 40 and 20 are then removed as one assembly and rotated 180° and remounted to the rocker plate 11. A second sighting of the cross hair locations on the toe and camber alignment chart 31 are recorded and compared with the previous sightings. If the two cross hair sightings do not fall on exactly the same locations on the chart 31 a slight adjustment of the adjuster lens pinion set screws 50 and 51 is made which reduces the discrepancy between the first and second readings by half, both horizontally and, vertically. The telescope assembly and mounting base 40 and 20 are again remounted in the first calibration position on the rocker plate 11. A new sighting is taken and, if required, minor adjustments of set screws 50 and 51 are again made and the process repeated until absolute agreement of cross hair locations is observed with the telescope assembly 40 and mounting base 20 oriented in the two 180° opposite positions on the rocker plate 11. When calibration is completed, the telescope assembly 40 and mounting base 20 are removed so that the telescope calibration plate 56 can be removed. The telescope assembly 40 and telescope assembly mounting base 20 can then be installed on the rocker plate 11 in the normal vertical position for wheel alignment procedures of the invention described earlier. 
     Turning now to FIG. 4b, a typical view by the mechanic at the eye piece 42 of the telescope assembly 40 is depicted. In FIG. 4b the right wheel being aligned by the optical alignment apparatus 10 indicates a toe-in condition of 15 minutes and a negative camber of -3/8&#34;. If these alignment settings were not within the desired tolerance for the particular race car, the mechanic would adjust the tie rod, and/or the control rod end until the toe and camber alignment chart 31, as viewed at the eye piece 42 at the proximal end of the telescope assembly 40 displayed the desired alignment settings. 
     While a preferred embodiment of the invention has been illustrated, it will be obvious to those skilled in the art that various modifications and changes may be made thereto without departing from the spirit of the invention as defined in the appended claims.