WO1990003304A1

WO1990003304A1 - A rider-propelled wheeled vehicle

Info

Publication number: WO1990003304A1
Application number: PCT/GB1989/001140
Authority: WO
Inventors: Francis Holland Green
Original assignee: Backwave Limited
Priority date: 1988-09-29
Filing date: 1989-09-27
Publication date: 1990-04-05
Also published as: IL91833A0; CN1041569A; ES2017037A6; AU4341589A; KR900701596A

Abstract

A rider-propelled wheeled vehicle, such as a bicycle, can be propelled both by leg movement, through pedals (18) driving a rear wheel (14), and through arm movement by moving the handlebars (20) in a rowing-like motion. The handlebars (20) are mounted on a parallelogram linkage (22) with horizontal pivot axes (26, 28) so that they maintain a substantially constant orientation throughout a vertical arc of motion, are arranged to operate through a drive mechanism to transmit drive to a driven wheel, and are connected to the steerable front wheel (12) through an elongate linkage of substantially fixed length which transmits steering torque along its length.

Description

A rider-propelled wheeled vehicle

This invention relates to a wheeled vehicle which can be propelled both by the legs and by arm and torso movement by the rider. A vehicle of this type in the form of a bicycle is described in United States Patent No 4 616 840. The invention can however be equally applied to a tricycle or to a tandem bicycle or more generally to other wheeled vehicles. For convenience however in the present specification the term "bicycle" will be used but this should not be construed in any way as limiting the scope of the claims.

The torso movement which can be used to propel the vehicle of the invention is similar to a rowing action.

Various proposals have been made in the past in order to overcome the problem of steering a bicycle of this type, but none have yet resulted in a practical machine.

According to the invention there is provided a rider- propelled wheeled vehicle with a frame, a steerable front wheel, a driven rear wheel, a seat for supporting the body of a rider, a pair of pedals arranged to be driven by the rider's legs so as to drive the rear wheel, and a set of handlebars mounted on the frame through a parallelogram linkage which has horizontal pivot axes and is connected to one of the wheels through a drive mechanism such that the handlebars are moveable in a vertical arc to drive said one of the wheels, and the handlebars being connected to the front wheel to steer the front wheel by an elongate link of substantially fixed length which transmits steering torque along its length.

The drive mechanism which connects the parallelogram linkage to the wheel driven by handlebar movement is preferably arranged to produce a forward driving action of the wheel on movement of the handlebars through the arc in both forward and reverse directions. In a preferred form of the invention, the wheel driven by the handlebar movement is the rear wheel.

Where it is the rear wheel which is driven by a handlebar movement, then both the pedals and the drive mechanism act on a common rotatable spindle mounted in the frame such that the spindle is driven in rotation both by the pedals and/or by the handlebars. A conventional drive can be

^' taken from this spindle to the rear wheel. The drive may for example be in the form of a chain which runs round a sprocket mounted on the spindle and a sprocket mounted on the driven wheel hub. A conventional gear changing arrangement can be used.

It is however possible and within the scope of the invention for the handlebars to drive the front wheel and for the pedals to drive the rear wheel. Different gearing arrangements can be provided between the handlebars and the front wheel and between the pedals and the rear wheel such that leg movement and arm and torso movement can be individually optimised.

In a preferred embodiment, the elongate steering link forms one link of the parallelogram linkage with the parallel link being a simple fixed length pivoted link. The elongate steering link then preferably comprises a rigid bar with a universal joint at each end.

The purpose of the parallelogram link is to ensure that the orientation of the handlebars relative to the rider stays substantially constant throughout the arc of movement. It will be appreciated however that a small variation in this orientation can be tolerated by the rider and therefore a small degree of non-parallelism of the linkage is acceptable. Such minor non-parallelism may result from the use of certain types of universal joint at the ends of the steering link.

The term "universal joint" is intended to cover all mechanisms which allow forces to be transmitted across the joint over a range of relative orientations between the components on either side of the joint. For example a flexible rubber universal joint such as is conventionally used at the foot of the mast of a sailboard is one possibility, and other universal joints known from other fields of technology will be known to the skilled man.

It is however desirable that the mounting of the handlebars on the linkage be free of play to give a rigid feeling to the bicycle as a whole, and therefore it is preferred to use a double-pivoted universal joint of the type used in motor vehicle drive shafts.

The handlebar drive mechanism is preferably arranged so that a forward driving action is produced on movement of the handlebars through the arc in both forward and reverse directions. This may be achieved by the use of a chain or belt drive using either a single chain or belt, or a pair of chains or belts. In either case it is necessary to have two one-way clutch mechanisms mounted on the spindle and oppositely arranged so that they transmit drive in opposite directions. Where a single chain or belt is used, then this must reverse itself so that it can pass over both drive devices. One point on the or each chain or belt will be connected to the parallelogram linkage so that the or each chain or belt performs a reciprocating motion as the handlebars are moved backwards and forwards through the arc. The one way clutches may be ratchet freewheel devices as conventionally used on the driven wheel of a bicycle but other types of clutches including one-way frictional clutches could alternatively be used. The chain or belt may be a conventional bicycle type chain running around toothed sprockets, or a toothed belt running around suitably formed pulleys.

Where two chains or belts are used, then they may be arranged one either side of the vehicle frame. Some form of tensioning device may be included to maintain the tautness of the or each chain or belt.

The bicycle will normally have a conventional braking system. It is desirable, when the front wheel is braked, to prevent the handlebars from moving forwards. Should the handlebars continue to be free to move forwards at the time when the front wheel is braked, then the rider will experience an uncomfortable feeling of falling forwards. Under these circumstances however it is not necessary to restrain reverse movement of the handlebars.

Because the brake for the parallelogram linkage should be operated simultaneously with the front wheel brake, the brake lever may operate two control wires, one leading to the front wheel brake and one leading to the parallelogram linkage brake. Conveniently the brake for the parallelogram linkage can be arranged to act on the drive mechanism and may take the form of a spring-loaded pawl which engages either with the chain or belt or with a wheel around which the chain or belt runs to prevent movement of the chain, belt or wheel in one direction but to continue to allow movement in the other direction. Under normal operation the spring loading of the pawl will hold the pawl clear of the drive mechanism. When the front brake is activated, then the spring loading will be overcome and the pawl will engage in the drive mechanism.

In addition to the brake for the parallelogram linkage which comes into operation only on application of the front wheel brake, a manually selectable lock can be included which immobilises the parallelogram linkage altogether so that the bicycle can thereafter be driven with fixed handlebars through leg movement only in the same manner as a conventional bicycle. The lock may be operable to lock the handlebars in a variety of different positions and can be actuated from the handlebars.

The seat may be in the form of a saddle mounted on a horizontal pivot axis and may be connected by a system of articulated links to the drive mechanism so that when the drive mechanism moves as a result of handlebar movement, the saddle is also tilted. The amount of tilt can be controlled by altering the length of the articulated links. The saddle may have a seat and a backrest which are connected to one another for common pivoting movement.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side view of a bicycle in accordance with a first embodiment of the invention;

Figure 2 is a detailed view of part of the drive mechanism from the bicycle of Figure 1;

Figure 3 is a cross section through the bottom bracket of the bicycle of Figure 1, on the line III-III; Figure 4 is a side view of a second embodiment of bicycle in accordance with the invention;

Figures 5 and 6 are respectively views from one side and from the other side of a third embodiment of bicycle in accordance with the invention;

Figure 7 is a cross section through the bottom bracket of the third embodiment of the invention, on the lines VII-VII;

Figure 8 shows a detail of part of the drive mechanism used in both the second and third embodiments;

Figure 9 is another detail of the same drive mechanism shown in Figure 8;

Figure 10 shows a detail of part of the drive mechanism from Figure 6; and

Figure 11 shows details of a handlebar lock mechanism applicable to the second and third embodiments.

The bicycle shown in the Figures has a frame 10, a steerable front wheel 12, a driven rear wheel 14, a saddle 16, a pair of pedals 18 and a set of handlebars 20. The handlebars 20 are mounted on the frame 10 through a parallelogram linkage generally designated 22 which has horizontal pivot axes at 24,26,28,30 and is connected to the rear wheel 14 through a drive mechanism which will be described in more detail below. The handlebars are moveable in a vertical arc indicated at 32 and movement in this arc produces drive through the drive mechanism which is applied to the rear wheel. The frame 10 has a bottom bracket in which a spindle 34 is mounted for rotation. The pedals 18 are connected to a sprocketed chain wheel 36 so that rotation of the pedals about the axis of the spindle turns the chain wheel 36 and drives a drive chain 38 which drives the rear wheel 14, optionally through a system of conventional gear wheels 40.

The parallelogram linkage 22 is made up of two elongate links 42 and 44. The link 42 is a simple rigid link with plain horizontal pivots at 26 and 28, and with a downwardly extending lever arm 46 extending below the lower axis 28. The other link 44 however is provided at top and bottom with a universal joint. The universal joints are held in a fixed position relative to the longitudinal axis of the link 44 and connect the link 44 respectively to the handlebars 20 and to front wheel forks 48 through which the front wheels are steered. Because the universal joints are fixed axially, the length of the link 44 remains constant throughout the arc of movement 32. However if the handlebars are turned to steer the wheel, the link 44 will turn about its own longitudinal axis to transmit steering torque from the handlebars to the forks 48. This arrangement will be described in more detail with reference to Figure 8.

Figure 2 shows a detail of the upper part of the drive mechanism by which drive is transmitted from the handlebars to the spindle 34.

A sprocket wheel 50 is mounted for free rotation on an axle 52 supported on two forwardly extending frame arms 54 of the frame 10. The ends of the axle 52 are extended beyond the frame arms 54 to form foot rests which can be used when the bicycle is being driven by torso movement alone. A conventional bicycle chain 56 passes around the sprocket wheel 50 and is attached to the extension 46 of the parallelogram link 42. The part of the chain 56 which is not visible in Figure 2 extends to the spindle 34, and the route taken by the chain at its lower end will be described below.

As the handlebars 20 are moved through the arc 32, the extension arm 46 will move backwards and forwards and-will therefore cause the chain 56 to travel in a reciprocating path. The sprocket wheel 50 will therefore rotate first in one direction and then in the other direction.

Figure 2 also shows schematically a brake 58 for braking the front wheel, the brake being operated by a Bowden cable 60. The brake would be operated from a conventional brake lever mounted on the handlebars 20. Although a stirrup- type brake is shown, a hub brake or any other type of bicycle brake could alternatively be used. When the brake 58 is applied, it is desirable to prevent any further forward movement of the handlebars, and this object is achieved by the use of a spring-loaded pawl 62. The pawl is pivoted on a bracket 64 on the frame extension 54 and is normally held by a tension spring 66 in a position where it does not interfere with the sprocket 50. However when the front wheel brake is applied, a second Bowden cable 68 is operated to pull the lower end of the pawl against the force of the spring 66 so that the tip of the pawl engages in the teeth of the sprocket wheel 50 (as shown in Figure 2) and prevents further clockwise rotation of the sprocket. The locking of the sprocket in this way prevents further forward movement of the link 42 and thus of the handlebars 20. However reverse movement is still possible. The two Bowden cables 60,68 will normally be actuated simultaneously by one and the same brake lever. It will be clear to the skilled man that the action of the pawl 62 could be located at any point along the path of the drive mechanism between the handlebars and the spindle 34, and could even be provided by a hub-type brake on the spindle axis. Figure 3 shows details of the spindle 34 mounted at the bottom of the frame 10. The main sprocket wheel 36 driven by the pedals and pedal cranks 18 is shown, together with two further sprocket wheels 70 and 72. These two sprocket wheels are driven by the chain 56, and are connected to an outer shaft 74 of the spindle through one-way clutches 76,78. These two clutches operate in opposite directions so that when the chain 56 is moving in one direction, one clutch is transmitting drive and the other is freewheeling and when the direction of travel of the chain reverses, then the other clutch transmits drive and the first freewheels.

Under normal driving conditions, the outer sleeve 74 of the spindle 34 rotates in bearings 80 and drives the chain wheel 36. An inner shaft 82 is however fitted within the sleeve 74, and the two pedal cranks 18 are attached to the end of this shaft. The shaft 82 and the sleeve 74 are connected by a third one-way clutch 84. This clutch is arranged so that when the outer sleeve 74 is being driven by the chain 56 through one of the clutches 76, 78 then it is possible for the pedals 18 to remain stationary and for relative rotation to take place between the sleeve 74 and the shaft 82. This allows the bicycle to be driven by handlebar movement alone, while the feet can backpedal or can be left on the pedals without the pedals turning.

Figures 4 to 12 of the drawings show a second embodiment of the bicycle where the parallelogram linkage and the drive mechanism are somewhat different from those described with reference to Figures 1 to 3. It will however be apparent to the skilled man that some of the features described with reference to the second embodiment can also be applied to the first embodiment, and vice versa. The bicycle shown has a front wheel 110, a rear wheel 112, a frame 114, a saddle 116 and handlebars 118. The bicycle has pedals 120 which turn a pulley wheel 122. A toothed drive belt 124 runs round the pulley wheel 122 and round a further pulley wheel on the hub of the rear wheel 112. A toothed belt is used in this embodiment because it is quieter and cleaner than a conventional chain.

A bracket 126 is mounted at the front end of the frame 114 above the forks 128 which control the front wheel. This bracket carries a central spindle 130 and a drum 132 is journalled on this spindle. A second toothed belt 134 is fixed around the periphery of the drum and also runs around pulley wheels 136 and 137 on a spindle journalled in the bottom bracket. Rotation of the drum 132 about the spindle 130 drives the belt 134 and this turns the pulleys 136 or 137 to transmit drive indirectly to the rear wheel.

The handlebars 118 are used to rotate the drum 132. The handlebars themselves are mounted in a handlebar carrier 140 and the carrier is connected by two equal length links 142 and 144 to the bicycle. The main link 142 is eccentrically secured to the drum 132 as shown particularly in Figure 8 whilst the lower end of the auxiliary link 144 is pivoted to the bracket 126 at 146. The path of movement of the handlebars is indicated in Figures 4, 5 and 6 in dotted lines with the two extremes of movement shown. When this movement, which is in a vertical arc, takes place then the drum 132 is rotated. Because of the parallelogram configuration produced by the links 142,144 the orientation of the carrier 140 remains substantially constant relative to the rider sitting on the saddle 116 throughout the range of movement and this enables the rider to steer and balance the bicycle in a safe and comfortable way. The handlebars are used to steer the bicycle in exactly the same manner as in a conventional bicycle. The seat 116 has a backrest 148. The angle between the seat and the backrest can be adjusted but once adjusted is normally set for that rider. In the embodiment shown in Figures 4, 5 and 6 the seat/backrest assembly 116,148 is also mounted on a pivot axis 150 on the frame and is connected to the drum 132 at a point 155 (Figure 6) offset from the bearing axis 130.

In this embodiment, steering action is transmitted from the handlebars 118 to the front wheel forks 128 by a fixed length steering rod 156 which is connected at its upper end through a universal joint 158 to the handlebars and at its lower end through two universal joints 160,162 arranged in series at the top of the front forks 128. It is to be noted that in this embodiment the steering rod does not itself define the parallelogram linkage and that therefore the rod may be replaced by other mechanisms which will transfer steering torque along their length. Although two universal joints 160,162 are used in this embodiment to achieve a large possible arc of movement, an arc of smaller but still sufficient dimensions can be achieved with the use of a single universal joint at each end of the rod 156.

Figure 4 shows an arrangement where a single drive belt 134 transmits drive from the handlebars to the chain wheel 122, and in this case an arrangement similar to that shown in Figure 3 will be used at the bottom bracket with the sprocket wheels 70,72 exchanged for pulleys which accept a toothed belt instead of a chain. However in an alternative embodiment shown in Figures 5, 6 and 7 two belts 163,165 are used, one of which transmits drive on forward movement of the handlebars and the other of which transmits drive on rearward movement of the handlebars. Referring now to Figure 7, the bottom bracket carries a spindle 138 supported in bearings 139 in a bottom bracket housing 141. The pedals and pedal cranks 120 are connected directly to the main pulley wheel 122. The belt 163 (Figure 5) passes over a second pulley wheel 143 supported on a one way clutch 145, and the belt 165 (Figure 6) passes over a third pulley wheel 147 connected to the spindle 138 through a second one way clutch 149. The belt 165 also passes around idler rollers 167,169, only one of which is visible in Figure 7 mounted in bearings 171 on a part 173 of the frame 114. The action of the clutches 145,149 will be opposed to one another so that when one is transmitting drive the other is freewheeling and vice versa.

Figure 8 shows more detail of how the steering mechanism operates. The handlebars 118 are supported on a stem 200 in a bearing 202. The lower end of the stem 200 is connected to the universal joint 158 and through this joint to the steering rod 156. At the lower end of the rod 156, through the universal joints 160,162 the rod 156 is connected to the top end of the steering forks 128. The top end of the forks is supported in a bearing sleeve 204 which forms part of the frame 114. When the handlebars are turned in a steering motion, the stem 200 rotates in the bearing 202 and the steering torque is transmitted through the rod 156 to the steering forks 128.

The rowing motion of the handlebars in their vertical arc is transmitted to the belt 134 (or to belts 163,165) through the links 142,144. The link 144 is journalled at its upper end at 206 on the handlebar carrier 140 and at its lower end 208 on the bracket 126 fixed to the frame. The other link 142 is pivoted at its upper end 210 to the handlebar carrier 140 and at its lower end is attached by means of fasteners 212 to a part of the drum 132 offset from the pivot axis of the drum 130. Because of this arrangement, the arcuate movement of the handlebars causes the drum to rotate first in one direction and then in the opposite direction and this leads to a reciprocating motion of the belt 134.

Tensioning of the belt or belts is carried out within the drum 132 and Figure 9 shows one arrangement whereby this can be done. In this Figure the periphery of the drum is open at two points 214,216 and a continuous loop belt 134 passes in one opening 214, around a tensioning pulley 218, around a pulley 220 on the spindle 130 and out through the opening 216. The tensioning pulley 218 is attached to the end of a threaded bolt 222 which can be turned to press the pulley 218 against the bolt and thus to tension the belt. The tensioning of the belt could however be carried out at any point along the length of the belt.

Also mounted on the frame 114 is a lock device 230 (Figures 8 and 11) located adjacent a disc 232, forming part of the drum 130. This can be seen in more detail in Figure 11. The device 230 has a bolt 236 which is spring loaded in the device by a compression spring 238 under the control of an operating cable 240. The bolt is normally retracted into the housing against the force of the spring 238 so that the drum 132 is free to rotate about its axis 130. However if it is desired to lock the handlebars and to use the bicycle as a conventional pedal cycle with only the pedals contributing to the driving movement, then the bolt 236 is extended by releasing the cable 240. The spring 238 then drives the bolt forwards into a hole 242 in the drum to lock the handlebars to the frame. The drum has a series of holes 242 around its periphery so that the handlebars can be locked in different positions as chosen by the rider. The control which operates the cable 240 can suitably be mounted on the handlebars or somewhere else where it can easily be reached by the rider. A similarly acting lock mechanism can be provided in the embodiment of Figures 1 to 3. If the handlebars are to be locked in this way, then it is desirable that they should be rigidly locked and that there should be no play. Alternative locking means other than that shown in Figure 11 can be designed to avoid any play.

It is characteristic of a conventional pedal bicycle that the front wheel steering is mounted in a substantially friction free manner on the steering axis. As a result, the cycle can be said to steer itself in that if the hands are taken off the handlebars the front wheel can be steered simply by the rider changing his or her weight distribution. This attractive characteristic is also provided by the steering mechanism of the bicycle described here.

Claims

1. A rider-propelled wheeled vehicle with a frame, a steerable front wheel, a driven rear wheel, a seat for supporting the body of a rider, a pair of pedals arranged to be driven by the rider's legs so as to drive the rear wheel, and a set of handlebars mounted on the frame through a parallelogram linkage which has horizontal pivot axes and is connected to one of the wheels through a drive mechanism such that the handlebars are moveable in a vertical arc to drive said one of the wheels, and the handlebars being connected to the front wheel to steer the front wheel by an elongate-link of substantially fixed length which transmits steering torque along its length.

2. A vehicle as claimed in Claim 1, wherein the elongate steering link forms one link of the parallelogram linkage.

3. A vehicle as claimed in Claim 1 or Claim 2, wherein the elongate steering link comprises a rigid bar with a universal joint at each end.

4. A vehicle as claimed in any preceding claim, wherein the drive mechanism is arranged to produce a forward driving action of said one of the wheels on movement of the handlebars through the arc in both forward and reverse directions.

5. A vehicle as claimed in Claim 4, wherein the drive mechanism comprises two one-way ratchet drive devices mounted on the spindle and arranged to transmit drive in opposite directions, and a single drive chain or belt which passes around both drive devices and which is connected to the handlebars so as to be moved in one direction or the other on movement of the handlebars.

6. A vehicle as claimed in any preceding claim, wherein the movement of the handlebars in a vertical arc drives the rear wheel.

7. A vehicle as claimed in Claim 6, including a drive output member in the form of a rotatable spindle, wherein the pedals are mounted on the spindle and the handlebars are drivingly connected to the spindle.

8. A vehicle as claimed in any preceding claim, wherein the pedals are drivingly connected to the rear wheel through a one-way drive device.

9. A vehicle as claimed in any preceding claim and having a brake for the front wheel and a brake for the handlebar movement, wherein when the brake is applied, the handlebars are prevented from further forward movement.

10. A vehicle as claimed in Claim 9, wherein the brake for the handlebar movement does not prevent backward movement of the handlebars.

11. A vehicle as claimed in any preceding claim, including a rider-operable lock which can be operated to immobilise the parallelogram linkage and to prevent any movement of the handlebars through the vertical arc.

12. A vehicle as claimed in any preceding claim, wherein the seat is in the form of a saddle mounted on the frame on a horizontal pivot axis and connected by a system of articulated links to the parallelogram linkage so that the saddle is tilted to and fro as the handlebars are moved forward and back.