Abstract:
A drive wheel and suspension for a vehicle for mounting on a steering post to provide both a steering capability and propulsion to the vehicle. The drive wheel and suspension provides a spring suspension for that wheel of the vehicle, as well as what is effectively vehicle body mounting of the propulsion system so as to minimize un-sprung weight and to provide a compact assembly to support a suitable aesthetic and protective fender over the drive wheel and suspension.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of front drive wheel suspension for vehicles. 
     2. Prior Art 
     T3 Motion, Inc., assignee of the present invention, now manufactures and sells the three-wheeled battery operated vehicle shown in  FIG. 1 . The vehicle is operated standing up, with all of the controls necessary being accessible on the handlebars. The vehicle has found wide application for security purposes, as it typically can operate all day in a typical application on a single charge, both indoors such as in shopping centers and outdoors for policing such areas as parking lots, parking structures, beach areas and the like. The vehicle has found wide use for such purposes not only because of its efficiency (cost of operation), but also because the operator is elevated somewhat, so can see over people for a better view of the area. 
     In the prior art vehicles as shown in  FIG. 1 , the wheels are rigidly mounted, that is, the rear wheels are rigidly mounted to the frame of the vehicle and the front wheel, which is the drive wheel, is rigidly mounted to an unsprung steering post, as in a typical tricycle. However because of the functionality and practical appeal of the vehicles, the same are being used in environments not having a particularly smooth operating surface, such as by way of example, poorly maintained parking lots and the like where rigid mounting of the vehicle substantially affects performance. A front drive wheel suspension also reduces torque at steering shaft due to the movement of suspension system during initial acceleration. Since the front wheel is the drive wheel as well as the steering wheel, it is important that the wheel remain one the ground, so to speak, and not bounce when going over a rough surface. This could be accomplished by partial deflation of the tire, though this leads to higher rolling friction (less range of a battery operated vehicle), poorer steering characteristics and accelerated wear on the time. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of a prior art vehicle in which the present invention may be used. 
         FIG. 2  is a first side perspective view of the suspension and drive of the present invention taken on an expanded scale compared to the subsequent Figures. 
         FIG. 3  is a second side view of the suspension and drive system. 
         FIG. 4  is a front view of the suspension and drive system. 
         FIG. 5  is a rear view of the suspension and drive system. 
         FIG. 6  is a top view of the suspension and drive system. 
         FIG. 7  is a bottom view of the suspension and drive system. 
         FIG. 8  is a first side perspective view of an alternate embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention comprises a resilient drive wheel for an electric powered vehicle such as that shown in  FIG. 1 .  FIG. 2  is a first side perspective view of an exemplary suspension and drive in accordance with the present invention.  FIG. 3  is a second side view of the suspension and drive system,  FIG. 4  is a front view of the drive and suspension,  FIG. 5  is a rear view of the drive and suspension,  FIG. 6  is a top view of the drive and suspension and  FIG. 7  is a bottom view of the drive and suspension, all of  FIG. 2 . As may be seen in the Figures, a rectangular tube  20  has an opening or socket into which a steering post for a vehicle such as that shown in  FIG. 1  will ultimately be fastened. Rearward projecting members  24  are fastened to bar  20  adjacent their forward ends and are configured to rotate around bearing assemblies  28 . Bar  20 , rearward projecting members  24  and bearing assemblies  28  are the only part of the assembly which are effectively rigidly connected or to be connected to a vehicle steering post. The rest of the assembly, to be hereafter described, rotates through a limited angle around the axis of bearing assemblies  28  in response to varying upward forces on wheel  30  through tire  26 . 
     In particular, wheel  30  is mounted on bearings on an axle  32  which is supported on substantially vertical struts  34 . These, in turn, are connected to a second rectangular tube  36  (an example of the first cross member in claims  1  and  2 ) with a reinforcing plate  38  providing extra rigidity to the substantially vertical struts  34 . Also connected to this assembly are side plates  40  and  46  ( FIG. 3 ) and member  44 , as well as motor mounting plate  48 . Motor mounting plate  48  supports motor  50  which drives a small toothed sprocket  52  which will drive a larger toothed sprocket  54  supported on bearings on side plate  46  and connected to a smaller toothed sprocket (not visible in the Figures) aligned with a larger toothed sprocket  58  connected to the wheel  30 . In the final assembly, toothed sprocket  52  will be coupled to toothed sprocket  54  by a toothed belt  57 , and small toothed sprocket coupled to toothed sprocket  54  will be coupled to toothed sprocket  58  through a second toothed belt  60 , with the various diameter ratios providing the desired speed reduction between the speed of rotation of the motor and the speed of rotation of the wheel  30 . The motor  50  is supported on the motor mounting plate  48  by bolts  56  passing through slots in the motor mounting plate  48  so that the motor may be slid back and forth as required for tensioning the belt between toothed sprocket  52  and toothed sprocket  54 . The belt  60  between toothed sprocket driven by toothed sprocket  54  and toothed sprocket  58  is tensioned by adjustment of the vertical position of axle  32  with respect to struts  34  by an adjustment screw  59  at each side of the assembly, which allows the exact position of the axle  32  of the wheel  30  with respect to the struts  34  to be varied. Note that the amount of variation in the final position of the adjustment needed to properly tension the respective toothed belt is small enough as to be non-consequential when the proper size of toothed belt is used. 
     Thus with the assembly just described it may be seen that the entire assembly, including the wheel and tire, the structure supporting the wheel and tire, as well as the drive motor  50  are free to rotate through a limited angle around the axis of bearings  28  with respect to rearward projecting members  24  connected to bar  20  (an example of the second cross member in claims  1 ,  2  and  7 ) and ultimately connected in recess  22  to a steering column of the vehicle on which the assembly is used. 
     Note that when the assembly shown in the Figures is used in a vehicle such as the vehicle of  FIG. 1 , rectangular tube  36  will be pushed upward toward rectangular tube  20 , being separated there from by urethane spring  62 , or alternatively as shown in  FIG. 8 , coil spring  62 ′ which are selected in size and firmness to provide a desired initial deflection dependent on the load to be supported by the suspension, the intended travel of the suspension and elastic resistance to upward motion of the wheel  30 . These urethane spring or coil spring are held in position by bolts  64  passing through the urethane spring or coil spring  62  and rectangular tube  36 , with an upper end of the bolts each having a flanged head on the bolts passing through holes in and being captured by rectangular tube to limit the downward travel of the suspension, i.e., the downward travel of wheel  30  relative to the rectangular tube  20 . 
     Thus it may be seen that urethane spring or coil spring  62  provide a cushioning affect for the wheel which will prevent or very substantially reduce the wheel bounce when traveling over a rough surface, thereby improving not only the comfort of the rider but also improving acceleration and steering under such conditions by keeping the wheel on the drive surface. The desired softness of the suspension may be selected by varying the dimensions and/or softness of the urethane or spring to provide the desired operating characteristics for the given application and load on the wheel. The net result is as good as some form of spring and shock absorber mount would be, and is a very substantial improvement over just effectively rigidly connecting the drive wheel to the vehicle and is substantially less expensive than a coil spring shock absorber assembly construction would be. 
     Thus the present invention has a number of aspects, which aspects may be practiced alone or in various combinations or sub-combinations, as desired. While a preferred embodiment of the present invention has been disclosed and described herein for purposes of illustration and not for purposes of limitation, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.