IL100208A - Bicycle with a front and rear wheel drive - Google Patents

Description

>mpm Τ)ΠΝΠ t?A A!? nyjn ronyo > y:i 0>>J3iN A bicycle with a front and rear wheel drive Efraim SHMEILIN C:- 84785 Δ BICYCLE WITH Ά FRONT AMD REAR WHEEL DRIVE FIELD AND BACKGROUND OF THE INVENTION The invention concerns a bicycle with both a conventional, rear-wheel drive and a front-wheel drive.

The traditional bicycle, generally driven by a feet-pedal mechanism had been modified in the art in order to utilise both arms and legs power in the course of riding. U.S. Patent No. 4,147,370 teaches a bicycle having a rear wheel assembly driven by the usual foot cranked sprocket and a front wheel assembly which is also chain- driven by a drive sprocket supported by the front suspension and steering system. The front drive sprocket is cranked by a reciprocating connecting rod, linked to the handlebars in which may be pivotably moved between a rearward and a forward position whereby they cause reciprocations of the connecting rod and consequently rotating of the front wheel. During its rearward and forward movement the handlebars may also be used to steer the bicycle.

This concept while employing two distinct driving assemblies, one leg-powered and the other arm-powered has a relatively complicated front wheel drive assembly which is required to convert the forward and rearward 'reciprocating movement into rotation of the drive sprocket. Moreover, the reciprocating movement of the rider ' s arms is not naturally combined with the feet rotational movement and furthermore it cannot be maintained for prolonged periods of time due to rapid tiring of arm-muscles.

Chinese Patent 85106803 and U.S. Patent No. 3,910,599 teach a bicycle using both arms and legs to drive a rear wheel and a front wheel, respectively, employing a rather complex mechanism to combine power generated by both limbs.

It is the object of the present invention to provide an improved bicycle utilising both arms and legs in synchronized motion to provide for comfortable and efficient riding.

GENERAL DESCRIPTION OF THE INVENTION In accordance with the invention there is provided a bicycle with both a front and rear wheel drive having a rear wheel drive assembly comprising a pedal-driven sprocket chain-linked to a rear-wheel sprocket, the bicycle being characterized in that: it has a front wheel drive assembly comprising at least one upper sprocket being a single sprocket or a gear system comprising a cluster of co-axial sprockets each of a different diameter, said at least one upper sprocket having an axle which is rotatably fixed onto the top of the front wheel steering stem and rotatable by a pair of substantially aligned hand grips projecting in opposite directions from the two sides of said upper sprocket, and has at least one lower sprocket being a single sprocket or a gear system comprising a cluster of sprockets each of a different diameter associated with a front wheel hub and capable of rotating it by means of a freewheeling mechanism; said upper and lower sprockets being essentially co-planner and linked to one another by means of a driving chain, whereby the rotation of the upper sprocket in the appropriate direction causes the rotation of the lower sprocket and consequently of the front wheel; and in that the ratio of diameter of said upper sprocket and said lower sprocket in said front-wheel drive assembly being identical with the ratio of diameter of said pedal-driven sprocket and said rear-wheel sprocket in said rear-wheel drive assembly.

Hitherto, all front-wheel driving mechanisms involved either a reciprocating horizontal movements of the hands, such as that disclosed in U.S. Patent 4,147,370 mentioned above or by the use of a rotational hand drive mechanism operating in a similar manner to that of the feet-pedals, namely a mechanism rotational by two pedals at 180° offset from one another. Such hand-driven mechanisms have a considerable drawback in that they cannot be maintained over prolonged periods of time. Additionally, as regards the hand-driven "pedal-type" mechanism, it has a further drawback in that it does not enable safe steering of the bicycle during riding.

These drawbacks of the prior art are overcome in accordance with the invention whereby the front-wheel is driven by a pair of aligned rotatable hand-grips. In rotation of such hand-grips the rider in fact utilizes the entire upper part of his body and the primary muscles operating in such a movement are the stomach muscles which are generally much stronger than the arms' muscles (this form of movement will be clarified from the description of the specific embodiments hereinbelow) . When stationary, the two aligned hand-grips allow a comfortable and safe steering of the bicycle, particularly in their most downward position, comparable with that of a bicycle with conventional handgrips.

As mentioned above, it is essential that the ratio between the diameter of the upper sprocket and the front-wheel sprocket in the front-wheel driving assembly, be identical to the ratio between the pedal-driven sprocket and the rear sprocket in the rear-wheel drive assembly. In one embodiment of the invention, the front-wheel drive assembly and the rear-wheel drive assembly comprise single upper sprocket and front-wheel sprockets and single pedal-driven rear sprockets, respectively. In accordance with another embodiment of the present invention, both driving mechanisms have a gear system consisting of a plurality of co-axial upper sprockets and/or front wheel sprockets in the front-wheel drive assembly and a plurality of pedal-driven sprockets and/or rear-wheel sprockets in the rear-wheel drive assembly. In such a case the control of the two gear systems should preferably be linked so that the identity in the aforementioned ratio between the two drive assemblies will be maintained.

In accordance with a preferred embodiment of the invention, the front-wheel drive assembly comprises an auxiliary support structure for the upper sprocket. Said auxiliary support structure may comprise a support member or a plurality of co-operating support members, one end of said support member or one member of said plurality of members being journaled to the axle of said upper sprocket and another end of said member or another member of said plurality of members being journaled to the axle of the front wheel.

In accordance with another preferred embodiment, the front-wheel drive assembly comprises a chain-guiding wheel located between the upper and the wheel sprockets. Such a guiding wheel may also serve for tensioning the chain.

The front-wheel drive mechanism is preferably a freewheeling mechanism of a kind in which rotation in the reverse direction acts as a brake. If desired, the front-wheel drive assembly, similarly as the rear-wheel drive assembly, may include a protective cover to the chain.

The bicycle of the invention may generally be manufactured from components used in the manufacture of conventional bicycles.

The bicycle of the invention may also be a multi-seat bicycle. Furthermore, the dual drive system in the bicycle of the invention may also be included in a trainer bicycle.

DESCRIPTION OF THE DRAWING For better understanding, the invention will now be described by way of example only, with reference to the annexed drawing, in which Fig. 1 is a side elevation of a bicycle in accordance with the invention with both a conventional, rear-wheel drive and a front-wheel drive; Fig. 2 shows the bicycle in two different riding positions.

DESCRIPTION OF A SPECIFIC EMBODIMENT Attention is first being made to Fig. 1 showing a bicycle 10 in accordance with the present invention comprising a standard rear-wheel drive assembly 11 and a front-wheel drive assembly 12. The rear-wheel drive assembly comprises a pedal sprocket 13 rotatable by means of pedals 14' and 14'' and linked by means of driving chain 15 to a rear-wheel sprocket 16. Sprocket 16 is preferably associated with rear-wheel 17 by means of a freewheeling mechanism, namely a mechanism whereby the wheel will continue its rotation by acquired momentum even without rotation of the pedals. This freewheeling mechanism is preferably of a kind wherein rotation of pedal sprocket 13 in the reverse direction will act as a brake ( such a freewheeling mechanism will be referred to hereinafter as "freewheeling brake mechanism").

Front wheel assembly 12 comprises an upper sprocket 20 rotatably attached by means of axle 21 to support stem 22 which is integral with and extends from a steering stem 23. Additional support to upper sprocket 20 is provided by first support member 25 journaled at its one, upper end to the axle 21 of upper sprocket 20 and at its other, lower end to the front end of second support member 26 which extends forward from and fastened to fork 28. Attached to the front end of second support member 26 are also the upper end of a pair of third support members 29 (only one of which being shown in this Figure) journaled at their other, lower end to front wheel axle 30.

Upper sprocket 20 is rotatable by a pair of aligned hand-grips 32 ' and 32 ' ' fixed on the end of arms 33 ' and 33'', respectively. Upper sprocket 20 is linked by driving chain 35 to front wheel sprocket 36 which is associated with front wheel 37 by means of a freewheeling mechanism, preferably a freewheeling brake mechanism. Support member 26 holds a chain guiding wheel 38 which also provides tension to the chain. Guiding wheel 38 is held by a screw extending through a slot 39 and may be fixed at various positions along the slot thereby adjusting the tension of the chain. If desired, the guiding wheel may also be biased towards the chain by means of a spring and the like.

In the embodiment shown in Fig. 1, the diameter of the rear-wheel sprocket 16 is identical to that of a front-wheel sprocket 36 and the diameter of pedal sprocket 13 is identical to that of upper sprocket 20. Consequently, during simultaneous front and rear wheel drive there will be a synchronous rotation of the upper and pedal sprockets. It should, however, be noted that synchronous rotation of the pedal and upper sprockets may also be achieved where the front wheel and rear wheel sprockets and the upper and pedal sprockets are not identical in diameter as long as the ratio between the diameters of the upper and front-wheel sprockets and that of the pedal and rear-wheel sprocket will be the same.

Attention is now directed to Fig. 2 which shows the bicycle of Fig. 1 in two different riding positions. In the riding position shown in Fig. 2a, the hand grips of the upper sprocket are in their most downward position in which the upper part of the body of the rider leans forward. By pulling the hand grips strongly using primarily the strong stomach muscles, the upper sprocket is rotated to the position shown in Fig. 2b in which the upper part of the rider's body is essentially upright. Then, by pushing the hand grips using again primarily the stomach muscles, the cycle is completed and the rider returns to the position shown in Fig. 2a. As can be noted from Figs. 2a and 2b, the rotation of the upper sprocket in the front wheel drive assembly and the rotation of the pedal sprocket in the rear wheel drive assembly are synchronous.

It is not always necessary to use both front and rear wheel drive, and at times of idle riding it may be desired to allow the front wheel to freewheel while driving the bicycle by means of the rear-wheel drive assembly. For freewheeling of the front wheel, the upper sprocket is suitably retained in the position shown in Fig. 2a which provides for easy steering of the front wheel.

Claims (4)

100208/3 - 8 - CLAIMS:

1. A bicycle with both a front and a rear wheel drive, having a rear wheel drive assembly comprising a pedal-driven sprocket chain-linked to a rear-wheel sprocket, and a sole upper sprocket directly driven by rotation of hand-grips and being chain-linked directly to a front-wheel sprocket; said upper sprocket is rotatably fixed onto the front wheel steering stem and supported by an auxiliary support structure in such position, that the axle of said upper sprocket is diverged forwards from the longitudinal axis of the steering stem.

2. A bicycle according to claim 1, wherein said auxiliary support structure is located ahead of the steering stem and comprises a support member or a plurality of co-operating support members, one end of said support member or one member of said plurality of members being journaled to the axle of said upper sprocket, and the other end of said member or another member of said plurality of members being journaled to the axle of the front wheel, thus distributing the load applied by a user to the upper sprocket between the steering stem and the auxiliary support structure.

3. A bicycle accoding to claims 1, or 2, wherein said auxiliary support structure comprises a substantially horizontal intermediate member connecting said steering stem to said structure and bearing a guide wheel for deflecting the front wheel driving.chain from the steering stem and adjusting tension of the chain. - 9- 100208/2

4. A bicycle according to any one of the preceding claims, wherein the front wheel drive mechanism is a freewheeling mechanism in which the rotation in the reverse direction acts as a brake. For the Applicants, DR. REINHOLD COHN AND PARTNERS