Drive wheel suspension

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.

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 inFIG. 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 inFIG. 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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention comprises a resilient drive wheel for an electric powered vehicle such as that shown inFIG. 1.FIG. 2is a first side perspective view of an exemplary suspension and drive in accordance with the present invention.FIG. 3is a second side view of the suspension and drive system,FIG. 4is a front view of the drive and suspension,FIG. 5is a rear view of the drive and suspension,FIG. 6is a top view of the drive and suspension andFIG. 7is a bottom view of the drive and suspension, all ofFIG. 2. As may be seen in the Figures, a rectangular tube20has an opening or socket into which a steering post for a vehicle such as that shown inFIG. 1will ultimately be fastened. Rearward projecting members24are fastened to bar20adjacent their forward ends and are configured to rotate around bearing assemblies28. Bar20, rearward projecting members24and bearing assemblies28are 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 assemblies28in response to varying upward forces on wheel30through tire26.

In particular, wheel30is mounted on bearings on an axle32which is supported on substantially vertical struts34. These, in turn, are connected to a second rectangular tube36(an example of the first cross member in claims1and2) with a reinforcing plate38providing extra rigidity to the substantially vertical struts34. Also connected to this assembly are side plates40and46(FIG. 3) and member44, as well as motor mounting plate48. Motor mounting plate48supports motor50which drives a small toothed sprocket52which will drive a larger toothed sprocket54supported on bearings on side plate46and connected to a smaller toothed sprocket (not visible in the Figures) aligned with a larger toothed sprocket58connected to the wheel30. In the final assembly, toothed sprocket52will be coupled to toothed sprocket54by a toothed belt57, and small toothed sprocket coupled to toothed sprocket54will be coupled to toothed sprocket58through a second toothed belt60, 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 wheel30. The motor50is supported on the motor mounting plate48by bolts56passing through slots in the motor mounting plate48so that the motor may be slid back and forth as required for tensioning the belt between toothed sprocket52and toothed sprocket54. The belt60between toothed sprocket driven by toothed sprocket54and toothed sprocket58is tensioned by adjustment of the vertical position of axle32with respect to struts34by an adjustment screw59at each side of the assembly, which allows the exact position of the axle32of the wheel30with respect to the struts34to 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 motor50are free to rotate through a limited angle around the axis of bearings28with respect to rearward projecting members24connected to bar20(an example of the second cross member in claims1,2and7) and ultimately connected in recess22to 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 ofFIG. 1, rectangular tube36will be pushed upward toward rectangular tube20, being separated there from by urethane spring62, or alternatively as shown inFIG. 8, coil spring62′ 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 wheel30. These urethane spring or coil spring are held in position by bolts64passing through the urethane spring or coil spring62and rectangular tube36, 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 wheel30relative to the rectangular tube20.

Thus it may be seen that urethane spring or coil spring62provide 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.