GB2303595A

GB2303595A - Push-pull drive mechanism for bicycles, etc.

Info

Publication number: GB2303595A
Application number: GB9615665A
Authority: GB
Inventors: Alvin Holmes
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-07-27
Filing date: 1996-07-26
Publication date: 1997-02-26
Also published as: GB9615665D0

Abstract

A drive mechanism 10 to convert reciprocating motion of hands or feet into rotary motion comprises handles 34, 36 which can be moved in two opposite directions A, B by an operator, and are drivingly engaged through an endless wire or chain 24, drive sprockets 28, 30, 12, and 14, and idler sprockets 26 and 32 with a driven shaft (16, fig. 1). The shaft is driven in a single direction Z, whether the chain is going forwards or backwards. Foot stirrups (70, 72, fig. 5) may be used as well as, or instead of, the handles. Fig. 3 shows the mechanism which rectifies the direction of rotation. Outer gear 50 is driven by the wire or chain, while inner driven gear 52 is mounted on a spindle (54, fig. 4). Four pinions 58 are mounted on a carrier plate (56, fig. 4). Pairs of gears 60, 62 are also carried on a plate (64, fig. 4). Drive is transmitted one way through gears 62, and the other way through gears 60 and 62. Steering cables (108, 110, fig. 5) may be attached to the handles, as may brake levers and cables. The mechanisms disclosed may be used for driving pumps, generators, dynamos, or compressors.

Description

Drive Mechanism The present invention relates to a drive mechanism.

In particular the invention relates to drive mechanisms which can convert reciprocating motion to rotary motion.

For example, bicycles and similar self-propelled vehicles are commonly driven by a rider using his/her legs to drive a chain wheel through a pair of pedals and cranks. The drive from the chain wheel to the driven wheel is usually by means of a chain and intermediate gearing.

A more efficient way of converting the rider's energy into rotary motion would be for the rider to use either their arms or legs in a push/pull type of motion rather than for the legs to perform a rotary motion.

The present invention seeks to provide a drive mechanism which is not exclusive to the propulsion of bicycles and similar self-propelled vehicles in which the energy input is in the form of a reciprocating motion and that reciprocating motion is converted into a rotary motion.

Whilst the mechanism is particularly directed to bicycles and similar self-propelled vehicles it can also be used for other purposes eg driving pumps, generators, dynamos and compressors, although this list is not exclusive.

According to the present invention there is provided a drive mechanism to convert reciprocating motion into rotary motion, the mechanism comprising force transmitting means which can be moved in two mutually opposed directions by the hands and/or feet of an operator, the force transmitting means being drivingly engaged with a driven shaft of a machine through a force transfer arrangement which can drive the output shaft in a unitary direction irrespective of the direction of travel of the flexible force transmitting means.

In one arrangement the mechanism can include a pair of freewheel drive sprockets mounted on an output shaft and the force transmitting means comprises a continuous length of wire or chain which passes over both of the sprocket wheels, the motion of the wire or chain driving alternately each of the sprocket wheels in a unitary direction.

In a further arrangement the mechanism comprises gearing including an outer wheel over which the length of flexible In a further arrangement the mechanism comprises gearing including an outer wheel over which the length of flexible force transmitting means is arranged eg a wire or chain, a driven gear mounted on an output shaft, and intermediate gearing comprising at least one pinion driven by the outer wheel which can be selectively engaged with a second pinion which is in direct engagement with the driven gear or indirectly with the driven gear through an idler gear.

In both arrangements the movement of the length of flexible force transmitting means eg a wire or chain can be operated by hand or foot, or by both hand and foot.

In the case of a foot operated mechanism the free ends of the wire or chain can be attached to two depending pivoted levers, each of which can be operated by a foot.

It is preferred that in such an arrangement a tensioning device is provided to maintain tension in the wire or chain.

The drive mechanism can include an outer gear which transmits drive to a driven gear through pinions and two pairs of gears and via either, both pairs of gears and or, only one of the pairs of gears.

The present invention further seeks to provide an improvement upon the drive mechanism so as to incorporate a dwell period between the reversal of direction of the outer gear and the re-engagement of the outer gear of the gear train so as to maintain output drive from the driven gear.

According to a further feature the present invention there is provided a drive mechanism to convert reciprocating motion into rotary motion, the mechanism comprising an outer drive gear, a driven gear, at least one intermediate gear engaged with the driven gear, and a dwell gear which is selectively engageable with either the at least one intermediate gear, or directly engagable with the driven gear, the dwell gear being in permanent engagement with the outer drive gear.

The drive mechanism can have two intermediate gears engaged with each other, one of said intermediate gears being engaged with the driven gear, the dwell gear being selectively engagable with one or other of the said two intermediate gears.

The dwell gear can be located in a recess of a housing of the drive mechanism.

The driven gear can have its axis located off centre of the drive mechanism, or concentric relative to the drive mechanism.

The present invention will now be more particularly described with reference to the accompanying drawings in which: Figure 1 shows a diagrammatic perspective view of one form of drive mechanism according to the present invention; Figure 2 shows a partial elevation of part of the mechanism shown in Figure 1; Figure 3 shows a diagrammatic representation of a further form of drive mechanism according to the present invention;; Figure 4 shows an exploded view of the drive mechanism shown in Figure 3, Figure 5 shows a diagrammatic representation of another form of drive mechanism according to the present invention, Figures 6A and 6B show diagrammatic sections of further form of drive mechanism according to the present invention, Figures 7A and 7B show diagrammatic sections of still further form of drive mechanism according to the present invention, Figure 8 shows a diagrammatic exploded elevation of a further form of drive mechanism according to the present invention; Figure 9 shows a diagrammatic front elevation of the drive mechanism as shown in figure 8; Figure 10 shows a detail of the drive mechanism shown in figures 8 and 9; Figure 11 shows a modified form of drive mechanism according to the present invention; Figure 12 shows a modified form of the drive mechanism shown in figure 11; and Figure 13 shows a modified form of the drive mechanism shown in figure 9 in which the input and output drives are concentric.

Referring to figs 1 and 2 a drive mechanism (10) comprises a pair of free-wheel drive sprockets (12, 14) which are mounted on an output shaft (16). The shaft (16) is journalled in a bottom bracket (18) of a cycle frame (20), and a chain wheel (22) is mounted on one end of the drive shaft (16).

A wire or chain (24) which is continuous passes over pulleys (26, 28, 30 and 32) and around both of the sprockets (12, 14).

A pair of handles (34, 36) are secured to the wire or chain (24).

When the handles (34, 36) are pulled and pushed respectively in the direction of arrows "A", the sprocket (12) will be driven in the direction of arrow "X". The sprocket (14) will be free to turn in the direction of arrow "Y" whilst the shaft (16) is driven in the direction of arrow "Z".

When the handles (34) are pushed and pulled respectively in the direction of arrows "B" the sprocket (12) freely rotates in the direction of arrow "X1" whilst the sprocket (14) rotates in the direction of arrow "Y1" driving the output shaft (16) in the direction of arrow "Z".

It will be therefore appreciated that whatever the direction of travel of the wire or chain (24), the shaft (16) will always be driven in the direction of arrow "Z".

The pulleys (26, 28, 30, 32) can be positioned at any convenient location upon the cycle frame (20).

The handles (34, 36) can be replaced by foot pedals which are pivotally attached to the cycle frame enabling the rider to operate the wire or chain (24).

Referring to figs 3 and 4 there is shown a drive mechanism also for a bicycle comprising an outer gear (50) which can be driven by a wire or chain and an inner driven gear (52) which is mounted on a chain wheel spindle (54).

An oscillating carrier plate (56) which has limited rotational movement relative to the spindle (54) carries four rotatably mounted pinions (58).

Located between the pinions (58) and the driven gear (52) are four sets of the four pairs of gears (60, 62), mounted on an anchor plate (64). Each gear (62) is in direct engagement with the driven gear (52) whilst the gear (60) is an idler gear. The anchor plate (64) is fixed in position relative to the spindle (54).

The outer gear (50), the carrier plate (56), and the anchor plate (64) are assembled between two carrier plates (66, 68), so that the anchor plates, the outer gear (50) and the carrier plate (56) all relate relative to the spindle (54), but the anchor plate (64) remains stationary.

When the outer gear (50) is driven in a first direction each pinion (58) engages each gear (62) directly and drives the driven gear (52) in a first direction. When the outer gear (50) is driven in the opposite direction each pinion (58) engages the idler gear (60) which itself is in direct engagement with gear (62) so that the driven gear (52) continues to be driven in the same direction.

The driving arrangement for the outer gear (50) will be in the form of a wire or chain which passes over the outer gear and which can be operated by hand or foot in a similar manner to that described with reference to figs 1 and 2.

Referring to fig 5 there is shown a drive mechanism in which both hands and feet are used for propulsion. The drive mechanism comprises a pair of stirrups (70) and (72) which are pivotally mounted on arms (74) and (76), the arms (74) and (76) being rotatably mounted about axis AA. Each stirrup has a pulley (78) and (80) and the stirrups are connected together at their front ends by a length of wire or chain (82) which passes round pulleys (84) and (86).

A pair of free wheel sprockets (88) and (90) are mounted on a drive shaft (92) upon which a chain wheel (not shown) can be secured.

A wire or chain (94) has its ends anchored at point (96). The wire (94) passes from anchor point (96) over pulley wheel (78) and then several turns round free wheel sprocket (90). The wire then passes over pulleys (98), (100) and (102) and then several turns round free wheel sprocket (88) over the pulley (80) and back to the anchor point (96). The two lengths of wire between the pulleys (98) and (102) and the pulley (100) are each provided with a handgrip (104) and (106).

It will be appreciated that the free wheel sprockets (88) and (90) are driven both by the stirrups (70) and (72) which are operated by the feet and also by handgrips (104) and (106) in a similar way to that described with reference to fig 1 except that in the present case as will be appreciated both hands and feet are used to drive the shaft (92).

The cycle can be steered by means of cables (108) and (110) which are attached between the handlebars (112) of the cycle and the handgrips (104) and (106).

Each cable (108) and (110) is in the form of a brake cable and the length of the cable can be varied as in the case of a brake cable by operation of a lever or twist grip (not shown).

The lengthening or shortening of each cable (108) and (110) will serve to turn the handlebars (112) and thus the forks (114) of the cycle.

Brakes for the cycle can be operated by further levers (not shown) also mounted on the handgrips (104) and (106).

Referring to figures 6 and 7 there is shown a further form of mechanism for transmitting the drive to the chain wheel spindle.

The drive comprises a circular plate (116) which is keyed to a drive shaft (not shown) and two annular flanges (118) and (120) are bolted to the plate (116) one on each side of the plate.

Two drive plates (122) and (124) are mounted for rotation in spaces (126) and (128) between the flanges (118) and (120) and the plates. (116).

Each drive plate (122) and (124) is provided with a plurality of equi-spaced holes (122A) and (124A) respectively, and the plate (116) is provided with four equi-spaced holes (116A).

The holes (122A) and (124A) are tapered on one side only.

A drive wire or chain (130) passes over both of the drive plates (122) and (124).

The drive plates (122) and (124) drive the plate (116) in one direction only (arrow A) in the following manner. Whilst the plate (122) is being driven in one direction the plate (124) will be rotating in the opposite direction. A pin (132) is slidably mounted in each hole (116A) and in one direction the pins (132) engage in four of the holes (122A) in the drive plate (122) and drive the plate (116) in the direction of arrow A.

In another form of drive shown in figures 7A and 7B there are two drive plates (122) and (124) which are rotatable upon a hub (134).

The hub (134) is provided with a bearing surface (134A) upon which the drive plates (122) and (124) can rotate.

The drive plates (122) and (124) are each driven in opposite directions by means of the drive wire or chain (130) and are spaced apart from one another by light springs (not shown).

Each drive plate (122) has a threaded portion (122A) and (124A) respectively and these threads are mutually opposed that is one is left hand thread and the other is a right hand thread.

Similarly the hub (134) has two threaded portions (134B) and (134C) again mutually opposed threads that is one being a left hand thread and the other being a right hand thread.

The hub (134) is always driven in the direction of arrow A by either the drive plate (122) or the drive plate (124).

Referring to figure 7A, the drive plate (124) is engaged with the hub (134) by means of the threaded portions (124A) and (134B).

When the direction of rotation of the drive plates (122) and (124) reverses the pins (132A) will automatically disengage from the holes (122A) in the plate (122) and engage in four of the holes (124A) in the plate (124) which are being driven in the same direction as the drive plate (122) was rotating when the pins (132) were engaged with the holes (122A) in the plate (122). Thus the plate (116) will continue to be driven in the direction of arrow A.

Referring to figures 8, 9 and 10, there is shown a drive mechanism (110) comprising a pair of outer plates (112), a pair of rings (114) a drive gear (116), an dwell gear (118) a pair of intermediate gears (120) and (122) and a driven gear (124).

Each outer plate (112) has an arcuate recess (112A) which contains the dwell gear (118).

As will be seen from figure 2 the dwell gear (118) is in permanent engagement with the drive gear (116) and the intermediate gears (120) and (122) are in permanent engagement with each other whilst the intermediate gear (120) is in permanent engagement with the driven gear (124).

As will be described below the dwell gear (118) is either engaged with the intermediate gear (120) or the intermediate gear (122).

The driven gear (124) is mounted off centre of the drive mechanism (110) by means of a shaft (126) mounted on projections (114A) of the each ring (114) (see figure 3).

The outer gear (116) is engaged by an annular gear (128) which itself is driven by a wire or chain in a similar manner to the drive mechanisms described above.

It will be appreciated that the outer plates (112) and rings (114) are assembled together to form a static housing to enable the drive gear (116) to rotate relative to the plates and rings (112), (114). Thus in use when the gear (116) is rotated by the action of the annular gear (128) in direction "A" in figure 2, the dwell gear (118) will be moved to the right hand end, as seen in figure 2 of the arcuate slot (112A) and engages intermediate gear (120) which itself is in permanent engagement with the output drive gear (124) which will rotate in direction "x.

When the direction of rotation of the outer gear (116) is reversed to direction "B", when the wire or chain is pulled in the opposite direction, the dwell gear (118) will be transferred to the left hand end as seen in figure 2 of the arcuate slot (112A) so that the dwell gear (118) will engage the intermediate gear (122). The drive is thus transmitted to the driven gear (124) through the intermediate gear (120) and the gear (124) will continue to be driven in the direction of arrow "X".

Thus whatever the direction of rotation of the outer gear (116) the driven gear (124) will be driven in the direction of arrow "X".

It will be further appreciated that as the dwell gear (118) has to run along the length of the arcuate slot (112A) before the drive to the gear (124) is re-engaged there will be a dwell in the transmission of the drive.

The delay thus provides a pause for the rider or operator of any mechanism employing the drive mechanism rather than requiring a continuous input of energy to drive whatever load is connected to the output of the drive mechanism, when the direction of the input to the drive mechanism is reversed.

Referring to figure 11 there is shown a simplified form of drive mechanism only requiring three gears. In figure 11 there is shown a drive mechanism (130) comprising a drive gear (132), a dwell gear (134) an intermediate gear (136) and a driven gear (138).

The dwell gear (134) is mounted for movement in an arcuate slot (138) and the drive mechanism (130) is assembled in a similar manner to that described with reference to figures 8 to 10 inclusive.

The dwell gear (134) is permanently engaged with the drive gear (130) which itself is driven in a similar manner to that described with reference to the drive mechanism shown in figures 1 to 3 inclusive.

As shown in figure 11 the dwell gear is located at the extreme right hand end of the arcuate slot (138). and engages with the intermediate gear (136) so that when the drive gear (132) is rotated in direction of arrow "A" the driven gear (138) rotates in the direction of arrow "X".

When the direction of rotation of the drive gear (132) is reversed to the direction of arrow "B" the dwell gear (134) is moved to the extreme left hand end of the arcuate slot (138) and engages directly with the driven gear (138) which will continue to be driven in the direction of arrow "X".

In order to increase the length of the dwell time the length of the arcuate slot in the drive mechanism can be increased as shown in figure 12 in which corresponding components have been given the same reference numbers as shown in figure 11.

It will be appreciated that the drive mechanism illustrated in figure 12 works in a very similar manner to that described with reference to figure 11 with the exception that the dwell period is increased because a greater degree of rotation of the drive gear (132) is required to move the dwell gear (134) from one end of the slot (140) to the other.

Similarly with reference to figure 13, there is shown a drive mechanism similar in many respects to that shown in figures 8 to 10 inclusive and corresponding components have been given the same reference numbers.

The length of the slot (112A) has been increased and thus the dwell period is increased because the length of time for the dwell gear (118) to traverse the length of the slot (112A) is increased.

A further difference to be noted however is that the driven gear (124) is located concentrically with the axis of the drive gear (116).

Thus the driven gear of the drive mechanism can be located concentrically or eccentrically of the axis of the drive gear (116).

It will be appreciated that the gear ratio of the drive mechanism according to the present invention can be modified by appropriate choice of the size of all of the gears which comprise the drive mechanism.

Whilst the invention has been described with particular reference to bicycles, wheelchairs and similar self-propelled vehicles it can also be used to enable a person to drive a wide range of machinery, eg pumps, compressors, dynamos, generators and machine tools though this list is not exclusive.

Claims

1. A drive mechanism to convert reciprocating motion into rotary motion, the mechanism comprising force transmitting means which can be moved in two mutually opposed directions by the hands and/or feet of a operator, the force transmitting means being drivingly engaged with a driven shaft of a machine through a force transfer arrangement which can drive the output shaft in a unitary direction irrespective of the direction of travel of the flexible force transmitting means.

2. A drive mechanism as claimed in claim 1 including a pair of free wheel drive sprockets mounted on an output shaft and a flexible force transmitting comprising a continuous length of wire or chain which passes over both of the sprocket wheels the motion of the wire or chain driving alternately each of the sprocket wheels in a unitary direction.

3. A drive mechanism as claimed in claim 2 in which the mechanism comprises gearing including an outer wheel over which the length of flexible force transmitting means is arranged, eg a wire or chain, a driven gear mounted on an output shaft and intermediate gearing comprising at least one pinion driven by the outer wheel which can be selectively engaged with a second pinion which is in direct engagement with the driven gear or indirectly with a driven gear through an idler gear.

4. A drive mechanism as claimed in claim 2 or claim 3 in which the length of flexible force transmitting means eg a wire or chain can be operated by hand or by foot or by both hand and foot.

5. A drive mechanism as claimed in claim 4 in which the free ends of the wire or chain can be attached to two depending pivoted levers each of which can be operated by a foot.

6. A mechanism as claimed in claim 5 including a tensioning device to maintain tension in a wire or chain in operation.

7. A drive mechanism to convert reciprocating motion into rotary motion, the mechanism comprising an outer drive gear, a driven gear, at least one intermediate gear engaged with the driven gear, and a dwell gear which is selectively engagable with either he at least one intermediate gear or directly engable with the driven gear, the dwell gear being in permanent engagement with the outer drive gear.

8. A drive mechanism as claimed in claim 7 including two intermediate gears engaged with each other, one of said intermediate gears being engaged with the driven gear, the dwell gear being selectively engagable with one or other of the said two intermediate gears.

9. A drive mechanism as claimed in claim 7 or claim 8 in which the dwell gear can be located in a recess of a housing or the drive mechanism.

10. A drive mechanism as claimed in any one of the preceding claims 7 to 9 in which the driven gear can have its axis of rotation located concentrically or eccentrically of the drive gear.

11. A drive mechanism as claimed in any preceding claim including an annular gear engagable with the drive gear, the annular gear being driven via a wire or chain which is moved in a reciprocating motion.

12. A drive mechanism constructed and arranged for use and operation substantial as herein described and with reference to the accompanying drawings.