GB2349125A

GB2349125A - Bicycle gearbox providing oscillating movement of pedals

Info

Publication number: GB2349125A
Application number: GB9909352A
Authority: GB
Inventors: Josef Petr Prokopius; Robert Jonasar; Orn Jonasar
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-04-24
Filing date: 1999-04-24
Publication date: 2000-10-25
Also published as: GB9909352D0

Abstract

A bicycle gearbox arrangement comprises two radial one-way clutches 10, 11 fitted between pedal crankshaft 3 and reverse bevel gearing 6, 7 and 8. When a downward force is applied to pedal 1 one-way clutch 10 locks and gear 6 rotates, thereby turning chain sprocket 15. Gear 6, via idle gear 8, also rotates gear 7 in an opposite sense so that one-way clutch 11 is allowed to freewheel. When a downward force is applied to pedal 2 one-way clutch 11 locks and gear 7, via gear 8, rotates gear 6 while one-way clutch 10 freewheels. The arrangement allows the pedals 1, 2 to oscillate about 45{ up and 45{ down of a horizontal position of the pedals while the gearing reverses the opposite rotational movement of the pedals. In another embodiment the bevel gearing may be replaced with spur or helical gearing (see fig 4) and the one-way clutches may be of an axial ratchet type.

Description

Bicycle gearbox.

Traditional bicycles are powered by pedaling through 360 angle in forwards direction where the pedals are in disposition at 180 angle alike crank. The cyclist can apply force through his legs to the pedals connected to the chain sprocket and by chain the rotary movement is transferred to the back wheel of the bicycle. The disadvantage of such a bicycle lies in overcoming at each revolution of the sprocket two dead centres top and bottom of the pedals at and leverage of the pedals is continuously changing, therefore in pedal angles near and through top and bottom dead centre the force applied to the pedals has a small leverage and so a very low effect of applied force to power the bicycle results.

The maximum effect is at the horizontal position of the pedals and minimum effect is at the vertical position.

Disclosure of the invention: This invention enables the cyclist to use the force and energy efficiently and take advantage of the best leverage of the bicycle pedals near horizontal position where the cyclist by pedaling through part of revolution downwards and upwards uses the maximum leverage resulting in saving a lot of energy put into the pedaling.

In bicycle racing it will provide the cyclist with advantage to pedal without overcoming the inefficient top and bottom dead centre by oscillating the pedals upwards and downwards through the maximum leverage achieving greater speed for less effort. Any cyclist can benefit from this advantage which also allows traditional pedaling through 360 angle.

This invention is introducing a simple gearbox situated at the pedal shaft with one way clutches to improve efficiency and save human energy when cycling. Referring to the accompanying drawings there is provided: Fig. 1. shows the basic principle of powering the bicycle by pedaling forwards through 360 angle where the top and bottom dead centre occurs twice per revolution of the large chain sprocket.

Fig. 2. shows the basic principe of pedaling in accordance with this Invention where the cyclist uses the maximum leverage when pedaling by oscillating the pedals through part of the revolution approximately through 45 angle up and 45 down in off the horizontal position of the pedals.

Fig. 3. illustrates one of the alternatives in accordance with this Invention where a forwards pedal 1, and a backwards pedal 2 are rigidly mounted to the ends of a central shaft 3 mounted in the housing of the gearbox 4 and supported by bearing 16,17 and 18, each bearing being an independent bearing or part of one of the one way clutch 10 and 11 freewheeling in one sense of rotation and engaging in the other sense of rotation between the shaft 3 and one of the bevel gears 6 and 7, the two one way clutches being orientated in opposite rotational engagement so that when one is engaging the second one is freewheeling and vice versa. The bevel gears are supported in the gearbox housing 4 by bearings 13 and 14. To the bevel gear 6 is mounted the large chain sprocket 15 which is by a chain connected to the back wheel sprocket powering the bicycle. The two bevel gears 6 and 7 are coupled together through at least one idler gear 8 rotating on a shaft 20 through radial bearing 12 and axial bearing 19 and the shaft 20 fixed to the gearbox housing 4 in some conventional way. When downwards force is applied to the pedal 1 the one way clutch 10 engages between the shaft 3 and bevel gear 6 and the sprocket 15 is rotating in the forwards direction powering the bicycle. When downwards force is being applied to the pedal 2, the one way clutch 11 engages between the shaft 3 and bevel gear 7 and through the idle bevel gear 8 the rotational sense is reversed and transmitted to the bevel gear 6 which rotates forwards and to the chain sprocket 15 also rotating in forwards direction powering forwards the bicycle. Item 5 is a part of the bicycle frame.

Fig. 4. illustrates alternative of this Invention using spur or helical gears. The pedals 1 and 2 are rigidly mounted to the ends of a shaft 3 having an arrangement such as splines or key or a pin and a slot off the centre part of shaft 3 as to provide rotational engagement with gear 9 allowing axial movement of the gear 9 from or to engagement by raised above the surface of shaft the means of rotational engagement between the shaft 3 and the gear 9. The one way clutch 22 has formed matching ratchet teeth projecting from end-faces of gear 6 and 9 for the rotational engagement and opposite rotation for freewheeling. In engagement the of the clutch 22 gear 9 is held by a spring 13. The gear 9 is also in rotational engagement with an idler gear 10 and further the gear 10 is rotating freely on the shaft 12 and engaging with a gear 8 maintaining the rotational sense of gear 9. The gear 8 and 9 have formed at their respective faces ratchet teeth 23 for one way rotational engagement opposite to the rotational engagement of gears 6 and 9. The gears 6 and 7 are freely rotating on their respective shafts 3 and 11. To the gear 6 is secured a large chain sprocket 15 which rotates in the forwards direction during pedaling-oscillating. When oscillating the pedals and force is applied downwards to the pedal 1, the gear 9 engages through one way clutch 22 with gear 6, the one way clutch 23 is freewheeling and the chain sprocket is rotating forwards powering the bicycle' forwards by means of a chain to the back wheel sprocket. When downwards force is applied to the pedal 2, the gear 9 rotates in the opposite direction, the engaged idler gear 10 with the gears 8 and 9 maintains the opposite rotation of the gear 8 and the one way clutch 23 engages with the gear 7 transmitting the forwards rotational movement to the gear 6 with the sprocket 15 in the forwards direction also powering the bicycle forward. The springs 13 and 14 ensure engagements of the one way clutches 22 and 23. The gear arrangement is mounted in the gearbox housing 4 which is mounted to the bicycle frame 5 and the shafts 3 and 11 are supported by their respective bearings 18,19,20,21 and 24 and the idle gear is supported by a bearing 25. Alternatively, the gears 8,9 and 10 can be replaced by a chain sprockets mounted in the same manner to shaft 3 and 11 connected by a chain to provide the functions of the gears 8,9 and 10.

Claims

CLAIMS.

1. A bicycle gearbox arrangement built around the centre part of the pedal crank shaft, the shaft being common to both left and right hand pedal cranks, the pedals positioned 1802apart as conventional and the gearbox arrangement serving the purpose of obtaining a higher efficiency from human effort by oscillations of the pedals about 45 up and 45 down relative to the horizontal position of the pedals thus employing the maximum leverage of the pedal cranks which results in obtaining a maximum torque for the minimum effort for powering the bicycle and in this way eliminating the inefficient top and bottom dead centres of the pedals which otherwise occurs twice per revolution of the pedal crank shaft if pedaling in the conventional way in a full circle of 360 ; the bicycle gearbox arrangement comprising at least two one-way rotational engagement elements for engaging rotational movement in one rotational sense and freewheeling in the opposite sense of which at least two are set back to back to each other so that when one is engaged the other is freewheeling and an arrangement of at least three gears for reversing rotational sense from backwards to forwards rotational sense, so that the first rotational engagement element engages directly between the pedal crank shaft and the output member, the output member having secured to or being a part of a second gear of the gearbox arrangement where during the forward movement of the pedal oscillations or during pedaling forward through the full circle of 360D as with the traditional bicycle pedals which this arrangement also allows, while during this forward engagement the second one-way rotational engagement element is freewheeling, and the second one-way rotational engagement element engages directly between the pedal crank shaft and a first gear of the said reversing arrangement during the backwards rotational movement from the oscillation or backwards pedaling so that the first gear rotates backwards while the first one-way rotational engagement element is freewheeling, the first and the second gears being spaced apart and accommodating between at least one third gear meshing in rotational engagement with the first and second gears so as to provide in this gearbox arrangement the means of reversing the backwards rotational movement from oscillating the pedals or from backwards pedaling to forward rotational movement of the second gear and so the output member to which a chain sprocket is secured and by means of a chain the rotation is transmitted to the back wheel of the bicycle.

2. A bicycle gearbox arrangement as claimed in Claim 1 where the one-way rotational engagement element is a radial mechanical device, known as an one way clutch, allowing the radial rotational engagement between two concentric rotational members in one sense of rotation and allows freewheeling of the two members in opposite rotational senses.

3. A bicycle gearbox arrangement as claimed in Claim 1 where the one way rotational engagement element is an axial mechanical device, known as an one way clutch, allowing the rotational engagement of two concentric rotational members by axial connection in one sense of rotation and freewheeling of the two members in opposite rotational sense.

4. A bicycle gearbox arrangement as claimed in Claim 1, Claim 2 and Claim 3 which allows the rider to exploit the maximum leverage of the pedals and eliminates the inefficient top and bottom dead centre in the vertical plane by oscillating the pedals near the horizontal plane of the pedal cranks where the backward movement is reversed by means of the two one-way rotationally engaging clutches engaging in one sense of rotation and freewheeling in the opposite sense in an arrangement with at least three bevel gears where the movements of the pedal oscillations up and down about the horizontal plane are provide the means of rotation of the output member to which a chain sprocket is secured and from the sprocket the rotation being transmitted to back wheel by a chain to drive the bicycle forward.

5. A bicycle gearbox arrangement as claimed in any preceding Claim which allows the rider to pedal through 360 rotation forward and 360 backwards where the backward movement is reversed by the means of at least three bevel gears and at least two one way rotationally engaging clutches to provide the forward rotation of the output member to which is a chain sprocket secured and from the sprocket the rotation being transmitted to the back wheel by a chain to drive the bicycle forward.

6. A bicycle gearbox arrangement as claimed in any preceding Claim where the gearbox arrangement is constructed with at least two one-way clutches and three bevel gears, first, second and third gear, the clutches providing rotational engagement between the first said bevel gear and the pedal crank shaft and between the second bevel gear and the pedal crank shaft, each of the clutches engaging in opposite rotational sense, where the first and second gears are spaced apart concentrically on axis of the pedal crank shaft and at least one third bevel gear situated and rotating on a radial axis between the first and the second bevel gear and meshing with the said first and the second gear and this arrangement reversing the backwards rotational movement from the first bevel gear during the backwards movement of the pedal crank shaft to forwards rotational movement of the second gear and so of the output member to which is a chain sprocket secured and from the sprocket the rotation being transmitted to the back wheel by a chain to drive the bicycle forward.

7. A bicycle gearbox arrangement as claimed in Claim 1, Claim 2 and Claim 3 where the gearbox arrangement is constructed with two one-way clutches and five spur gears where two gears are situated concentrically on the first axis, being the axis of the pedal crank shaft, first of the gears being constructed together with the output member and a first one-way clutch, the first one-way clutch engaging between the first gear and the pedal crank shaft in forwards rotational sense and the second gear being rotationally secured to the pedal crank shaft and with a second shaft on a second axis parallel with the first axis, the second shaft axis spaced apart from the first axis, and a forth and fifth gear situated on the second shaft, the first and the fifth gear meshing in rotational engagement forming a first parallel pair of gears, the second and forth gear being of a smaller diameter independent in of each other and each meshing together in rotational engagement with a third auxiliary gear on a third shaft in a third axis parallel with the first and second axes and the second one-way clutch engaging between the forth and fifth gear during the backwards rotational movement of the pedal crank shaft from pedal oscillation or backwards pedaling while the first one-way clutch is freewheeling and the rotational movement from backwards pedaling transmitted in this arrangement to the first gear so to output member to which is a chain sprocket secured and from the sprocket the rotation being transmitted to the back wheel by a chain to drive the bicycle forward.

8. A bicycle gearbox arrangement as claimed in Claim 1, Claim 2 and Claim 3, Claim 4 and Claim 7 where the gearbox arrangement is constructed with spur gears and where two gears are situated concentrically on the first axis being the axis of the pedal crank shaft, one of the gears being constructed together with the output member freely rotating on the said shaft and the second gear having partial axial movement for one-way clutch engagement but rotationally secured to the pedal crank shaft, on the adjacent faces of these said two gears is formed axially the one-way clutch engaging in the forwards rotational sense of the pedal crank shaft and the clutch being held in engagement axially hs a sprinq, anrfl h ttv7n sears situated on a second shaft on a second axis parallel with the first axis, one or both free rotationally on the second shaft, the shafts spaced apart from the first axis, these two gears having also on their adjacent faces formed axially a second one-way engagement clutch axially engaging between these two gears in the opposite rotational sense from the first one-way clutch also being held in engagement by a spring, the gears opposite to each other forming two parallel gear trains where one of the gear trains meshing together in direct rotational engagement while the second gear train having the gears of smaller diameter and not in direct mesh or engagement where the engagement between these two gears is provided by an auxiliary gear on a third shaft on a third axis parallel with the first and second axes, the auxiliary gear meshing in rotational engagement in the said second gear train and the rotational movement from forwards directly and from backwards pedaling reversed and transmitted in this gearbox arrangement to the first gear so to the output member to which is a chain sprocket secured and from the sprocket the rotation being transmitted to the back wheel by a chain to drive the bicycle forward.

9. A bicycle gearbox arrangement as claimed in Claim 1, Claim 2 Claim 3 and Claim 4 where the gearbox arrangement is constructed with at least two rotational engagement elements, one pair of sprockets and one pair of spur gears where one sprocket and one gear of the pair are situated on the axis of the pedal crank shaft each having been set to engaged rotationally with the pedal crank shaft by the one-way rotational engagement clutch in opposite rotational sense to each other, so when one is engaged, the other is freewheeling and via versa and the second sprocket and second gear of the pairs rotationally secured together on a second shaft spaced radial apart and parallel with the pedal crank shaft, the pair of sprockets being rotationally connected by a chain and the pair of the gears in rotational mesh engagement where the gear first gear is secured to or being a part of the output member to which is a chain sprocket connected and rotation transmitted by a chain to the back wheel to drive the bicycle.

10. A bicycle gearbox arrangement as claimed in any preceding Claim where the output member is in a form of a sleeve on the pedal crank shaft rotationally connected with the said pedal crank shaft in one rotational sense and freewheeling in the opposite senses.

11. A bicycle gearbox arrangement as claimed in preceding Claims and as substantionally described elsewhere in this Invention and as illustrated on accompanying drawings.