GB2580782A

GB2580782A - Vehicles

Info

Publication number: GB2580782A
Application number: GB1918181.7A
Authority: GB
Inventors: Paul Cattell Rupert; George Packer John
Original assignee: Roadrower Ltd
Current assignee: Roadrower Ltd
Priority date: 2018-12-19
Filing date: 2019-12-11
Publication date: 2020-07-29
Anticipated expiration: 2039-12-11
Also published as: GB201820688D0; GB201918181D0; GB2589517B; GB202102279D0; GB2580782B; GB2589517A

Abstract

A vehicle has a driven element with the drive to the driven element provided by means of a first pivoted lever (a) designed to be moved by the arms of the driver of the vehicle, a second pivoted lever (b) designed to be moved by the legs of the driver of the vehicle, and a four-bar linkage system interconnecting the first and second pivoted levers (a & b) via four pivots (c, d, r, s). The driven element may be a wheel or propeller

Description

VEHICLES

Field of the Invention

This invention relates to vehicles and has for its object the provision of an improved form of vehicle that can be propelled by movements similar to those involved in rowing a boat.

Summary of the Invention

According to the present invention there is provided a vehicle having a driven element with the drive to the driven element provided by means of a first pivoted lever designed to be moved by the arms of the driver of the vehicle, a second pivoted lever designed to be moved by the legs of the driver of the vehicle, and a four-bar linkage system interconnecting the first and second pivoted levers.

If the vehicle is a road vehicle, the driven element will be a wheel whereas, if the vehicle is a boat, the driven element will be a propeller.

Brief Description of the Drawings

Figure 1 is a side view of a rowing bicycle, Figure 2 shows the progressive stages of the pull stroke during operation of the bicycle shown in Figure 1, Figure 3 is a view of part of the drive system, Figures 4 and 4a are sectional views of part of the drive system, Figures 5a -5c show progressive stages of part of the drive system, Figures 6 and 7 show the steering linkage mechanism,

Description of the Preferred Embodiment

Figure 1 shows the main components for a rowing bicycle.

The rider sits on seat p, operating the bicycle with handlebars o and pedals t. Handlebar assembly o rotates within the upper part of hand lever a. At the lower part of handlebar assembly o is mounted a constant velocity joint (shown in Figures 6 and 7) behind bearing c, the lower part of which is connected to steering arm m. This is connected by a spherical joint to steering link rod n, the front end of which is connected via a second spherical joint to fork steering arm u connected to the front forks.

The hand lever a pivots on bearings c located on frame f. Foot lever b is pivotally attached to frame f by bearings d. The hand and foot levers are connected by link rods e via bearings r and s, thus maintaining an angular relationship between hand and foot levers. The dynamic angular relationship is determined by the length of link rods e relative to the distance on the frame between pivot bearings c and d. The angular relationship may be altered to produce more movement of the hand lever at the beginning of a stroke compared to the foot lever, and conversely at the end of the stroke. The embodiment shown in the drawings has a fixed parallel relationship between hand and foot levers, wherein the lengths c-d and r-s are identical.

Chain rings g are attached to the hand lever a, and transfer driving force from the hand/foot lever linkage to clutch mechanism q via drive chains j and k. The clutch mechanism q converts oscillating motion to single direction rotary motion and drives the rear wheel via final drive chain h. Figure 2 shows the progressive stages of the pull stroke. The effective four-bar linkage formed by frame f, link rods e, hand lever a and foot lever b is shown in the top illustration.

Figure 3 shows part of the drive mechanism. During a pull-stroke, chain ring g, which is part of hand lever a, rotates, pulling chain j which turns clutch mechanism q in the opposite direction. Tension chain kl maintains tension in push chain k throughout the stroke.

Pushing the handlebars forward and retracting the legs constitutes a 'push-stroke'. The drive mechanism described allows the push-stroke to provide additional power to the rear wheel. During a push-stroke, push-chain k turns clutch mechanism q, whilst tension-chain j1 maintains tension in pull-chain j.

Figure 4 shows a section view clutch mechanism q. This includes means to convert oscillating rotary motion of any amplitude or direction to intermittent single direction rotary motion. The ratio of input motion to output angular velocity is varied by the use of non-circular sprockets. Also, a simple manually operated dog-clutch is incorporated to disengage the primary drive from the final drive, which enables the bicycle to be wheeled backwards. When engaged, the mechanism prohibits reverse movement of the rear wheel, so the addition of a disengaging clutch facilitates ease of manoeuvring the bike for parking or transporting.

Pull chain j from Figure 3 partially wraps around sprocket 6a. When pulled, this turns casing 4a and outer race of roller clutch 5a, the inner race of which is attached to outer axle 3. When the clutch mechanism is in the driving position, pins 8 of outer axle 3 engage with holes in axle assembly 2. Chain ring 1 attached to axle assembly 2 drives the rear wheel via chain h, see Figures 1 and 3. Tension chain j1 shown in Figure 3 partially wraps in reverse direction from chain j around sprocket 7a. Chains j and j1 are pulled by the chain rings g (Figures 1 and 3) in equal and opposite amounts. On a push stroke chain j1 rotates the pull-assembly 4a, 5a, 6a, 7a in reverse direction, maintaining tension in chain j.

One full pull stroke (90 degrees of rotation backwards) produces approximately 340 degrees of rotation of sprocket 6a. Because the muscles engaged during a push stroke are considerably weaker than those for the pull stroke, the mechanism embodies a lower-geared drive in this direction. Therefore sprocket 6b is approximately 30% larger that 6a, meaning that one full push stroke produces approximately 270 degrees of rotation of sprocket 6b. This enables a quicker push stroke and thereby improved ability for the rider to climb hills without slowing down during the push stroke.

Figure 4a shows the mechanism in the disengaged state. The primary drive is disengaged from the final drive by means of turning cam lever 9 by 180 degrees. This moves assembly 10, 11 axially outwards, and pin 11 acting in annular slot 12 of outer axle 3 moves the outer axle assembly, retracting pins 8 from holes 14 in the main axle assembly 2. When the cam lever 9 is released the mechanism is moved back to the engaged position by spring 13.

Figures 5a -5c shows progressive stages of the pull stroke for sprockets 6 and 6a moved by chains j and j1. In Figure 5a chain j is shown coiled around sprocket 6 at the start of a stroke, and in Figure 5c chain j is uncoiled at the end of a stroke. The effective gear ratios at these points are higher than at the middle of the stroke, shown in Figure 5b, meaning that, for a fixed forward velocity of the bicycle, the hand and foot levers move slowly at the beginning and end of a stroke, and more quickly in the middle. This improves on the use of circular sprockets for a reciprocating motion, reducing sudden acceleration and deceleration of the rider's mass, and transferring a portion of the kinetic energy to the mechanism, rather than solely the rider's muscles being used to decelerate the body and the end of a stroke.

Tension sprockets 6a and 6b are shaped so that, on the respective return strokes of the pull and push assemblies 4a, 5a, 6a, 7a and 4b, 5b, 6b and 7b, chains j and k are always in tension.

Figures 6 and 7 show the steering linkage mechanism. This is a constant velocity linkage, and thus produces a constant relationship between the input angle from handlebars and output angle to the front forks and wheel. The mechanism is able to tolerate shaft misalignment and axial position relative to the pivoting centre.

In Figure 6a, handlebar inner assembly 15 is in the forward position (start of pull stroke), pivot bearing c indicated by centre mark. Assembly 15 rotates within hand lever a (Figures 1 and 3). Upper link 16 pivots on clevis 17 of assembly 15 and lower link 18 is attached to upper link 16 via spherical joint 19, and pivots on clevis 19 of steering arm assembly 20. Spherical joint 21 connects the steering arm to steering link rod n.

Figure 6b shows the mechanism with handlebar assembly at the end of a pull stroke.

Figures 7a and 7b show the mechanism with handlebars turned to the right, with steering link rod pushed forwards, at the start and end of a pull stroke respectively.

One of the benefits of the drive mechanism is that it allows adjustment of the dynamic input to output ratio via non-circular sprockets on the clutch assembly. It also allows for different input to output ratios to be used for the pull stroke and push stroke.

A further benefit is that it includes a simple constant velocity joint which provides a constant input to output angle regardless of the tilt angle of the handlebars.

It will be appreciated that, although the invention has been described with reference to its application to a bicycle having a driven rear wheel, the invention could also relate to a boat having a propeller driven by a similar drive system.

Claims

Claims:- 1. A vehicle having a driven element with the drive to the driven element provided by means of a first pivoted lever designed to be moved by the arms of the driver of the vehicle, a second pivoted lever designed to be moved by the legs of the driver of the vehicle, and a four-bar linkage system interconnecting the first and second pivoted levers.
2. A vehicle as claimed in Claim 1, in which the driven element is a wheel.

3, A vehicle as claimed in Claim 1, in which the driven element is a propeller.