Elliptical drive system

An elliptical drive system for stepper type bikes that needs no chains or sliders for its operation. Its quadrilateral linkage minimizes the vertical motion of the user's feet while guiding the feet in a natural motion that resembles walking. The elliptical drive system is designed to give the stepper bike high ground clearance for traveling on rough terrain. Adjustment apertures on the linkage arms allow the user to adjust the length of linkage arms according to the user's leg length and overall size.

CROSS REFERENCE TO RELATED APPLICATIONS

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DESCRIPTION OF ATTACHED APPENDIX

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BACKGROUND OF THE INVENTION

This invention relates generally to the field of human powered systems and more specifically to an elliptical drive system for a stepper type bike.

Numerous designers have developed and patented stepper bikes where the rider is in a standing position and presses his feet down on pedals to create forward motion. The primary objective is to have the user's feet travel in an elliptical fashion, similar to a stationary elliptical training machine found in many gyms or private homes.

BRIEF SUMMARY OF THE INVENTION

Another object of the invention is to provide an elliptical drive system that eliminates the need for low hanging frame members, allowing for suitable ground clearance when operating on rough terrain.

A further object of the invention is to provide an adjustable linkage geometry that allows for optimal pedal path for different riders.

Yet another object of the invention is to provide a quadrilateral linkage that minimizes the vertical motion of the rider's feet, while guiding the feet in a natural motion, similar to that of walking.

In accordance with a preferred embodiment of the invention, there is disclosed an elliptical drive system comprising: left and right rear crank arms, left and right pedal platforms, left and right main horizontal drive arms, left and right vertical drive arms, left and right short horizontal drive arms, left and right short lower drive arms, main horizontal frame member having an integral upwardly angled frame extension, U shaped horizontal frame member, front fork and steering member, a rear wheel hub, said front fork and steering member rotatably attached to said main horizontal frame member, said left and right short horizontal drive arms rotatably attached to said upwardly angled frame extension, said left and right vertical drive arms rotatably pinned to the ends of said short horizontal drive arms, said left and right short lower drive arms rotatably pinned at one end to said main horizontal frame where said horizontal member meets said upwardly angled frame extension and on the opposite end pinned to a mid-point on said vertical drive arms, said left and right main horizontal drive arms pinned at on end to said vertical drive arms and at the opposite end pinned to said left and right rear crank arms, said left and right rear crank arms fixedly connected at their opposite end to said central rear wheel hub, and said U shaped horizontal frame member fixedly attached at one end to the distal end of said main horizontal member and at the opposite end to said rear wheel hub.

The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.

DETAILED DESCRIPTION Of The INVENTION

FIG. 1is a perspective view of the invention. The linkage of the present invention is attached to standard pneumatic wheels30and steering column31. Left and right rear crank arms2,4are fixedly attached to a shaft320of the central hub32of the rear wheel30. The linkage shown in the present invention includes left and right identical components that mirror each other. However, for simplicity sake, the following description may in some cases refer to the right side linkage only, with the understanding that the left side linkage operates in a similar way. Main horizontal drive members6,8are attached at one end to crank arms2,4and at that opposite end to vertical linkage member44. Vertical linkage members44are attached at their opposite ends to pivot shafts36. A short horizontal linkage member40is attached at one end to pivot shaft36and at the opposite end to frame shaft member24. The shafts24,36act as pivot points during operation. Another lower short linkage member42is attached at one end to a shaft member38and at the opposite end to a mid-point shaft22on vertical linkage member44. Linkage member44has a plurality of apertures at mid-point to receive pin22, to allow different adjustment options which affect foot platform stroke path. Vertical linkage member44is made up of a lower member and an upper member that can be slidably adjusted to increase or decrease the length of the vertical member44. A foot platform46is attached to the main horizontal drive member6and includes a toe retaining member34to help the user keep his feet on the platform46when the user lifts his or her foot during normal operation. The toe retaining member may be moved forward or backward depending on the user's shoe size. A main frame member16is attached to the rear hub assembly32via U shaped frame member28. The main frame member16angles upward at its front end46aand attaches to the front fork bearing housing20. Steering column31extends from the bearing housing20.

FIGS. 2,3,4,5are side views of the invention that show the linkage of the present invention in operation in a succession of orientations, each Figure shows the crank arms2,4at ninety degree intervals from one Figure to the next. The user's leg50can be seen in each phase of the rotational sequence. The linkage can be described as quadrilateral in that there are four linkage pivot points that cause effective operation of the elliptical stepper of the present design. TheFIGS. 2, 3, 4, 5, show each element of the linkage2,16,44,42in their respective locations at ninety degrees, one hundred and eighty degrees, two hundred and seventy degrees, and three hundred and sixty degrees.

FIG. 6is a top view of the invention where the left and right mirror image linkage members can be seen.

The main horizontal drive member6remains a significant distance from the ground during all phases of the linkage cycle thereby making it ideal for use on rough terrain.

The elliptical motion for the step platform46during operation minimizes the vertical motion of the rider's feet, while guiding the feet in a natural motion, similar to that of walking.

FIGS. 7 and 8are each a side view of a second embodiment of the invention200. InFIG. 7the closest crank arm210is at five o′clock.FIG. 8shows the crank arm210at six o′clock. This second embodiment200shows a left and a right curved roller track212that is more rigid and has less flex than the linkage of the first embodiment shown inFIGS. 1 through 6. In the second embodiment200, the track212the mount position of the curved roller track212can be changed to achieve different pedal paths for increased comfort and efficiency. The changing curvature of the roller track212also makes possible many different pedal stroke paths. In operation, a roller members204,206mounted in main vertical arms208,210ride and slide within curved track212, causing a smooth and efficient stroke path. The roller track212can also be straight in shape.