WO2002030733A1

WO2002030733A1 - Multi-speed gearset for bicycles

Info

Publication number: WO2002030733A1
Application number: PCT/AT2001/000323
Authority: WO
Inventors: Hermann Schmidt
Original assignee: Hermann Schmidt
Priority date: 2000-10-12
Filing date: 2001-10-10
Publication date: 2002-04-18
Also published as: AU2001293462A1

Abstract

The invention relates to a multi-speed gearset for bicycles with a rear wheel derailleur, comprising several rear chainwheels (10), connected to the rear wheel hub and a chain derailleur for transferring the chain from one rear chainwheel to another, with a pedal crankshaft (8), which is driven by the pedal cranks (7), comprising a front chainwheel (4) over which the drivechain (9) runs, to which the crankshaft is connected by means of a multi-speed planetary gear drive (11).

Description

Multi-speed transmission for bicycles

The invention relates to a multi-speed transmission for bicycles with a rear wheel derailleur, which comprises a plurality of rear sprockets connected to the rear wheel hub and a chain thrower for throwing over the drive chain from one rear sprocket to another.

Chain gears for bicycles are known in large numbers, for example also from DE-A1 19608088, DE-C2 3821792 and DE-A1 19636729. Usually in multi-speed bicycles nowadays such chain gears are provided both on the rear wheel and in the area of the pedal crankshaft. A disadvantage of these conventional derailleur gears for bicycles is that not all of the existing gears can be used. Those gears where there is a strong skew of the chain, which wears it out prematurely, should not be used in continuous operation. There is also a relatively large overlap area between the existing gears. If the chain runs over a first front sprocket, the ratios that can be selected by selecting the rear sprocket overlap with those that result from the selection of an adjacent front sprocket.

Multi-speed planetary gearboxes built into the rear wheel hub are also known. Usually 3-gear shifts are realized in this way, but a larger number of gears has already been achieved by such planetary gearboxes. Such planetary gears in the rear wheel hub are usually used in order to implement a coaster brake in addition to a gear shift. A disadvantage of these multi-speed planetary gear drives is that only a relatively small number of different gears are available.

Such multi-speed planetary gearboxes installed in the rear wheel hub are known for example from DE-A1 -3819065, DE-A1 -19618636, DE-C2-3440070 and DE-A1-4133988.

From DE 419 414 C, CH 182 102 A and DE 41 34 843 A1 two-speed planetary gear transmissions already known from the pedal crank of a bicycle are also known. When installing DE 41 34 843 A1, a multi-speed transmission is additionally provided in the rear wheel hub.

GB 2 336 575 A also shows a motor bike that can be driven both by a pedal crank and by an electric motor. The pedal crank and the electric motor act here via a planetary gear, on the one hand via the planetary gears (pedal-driven) and on the other hand via the sun gear (motor-driven) on the front chainring connected to the outer wheel. To enable a gear change, the motor bike can also be provided with a rear wheel derailleur.

The object of the invention is to provide a novel multi-speed transmission for bicycles, by means of which a large number of different gears can be implemented in a large translation range in a simple and advantageous manner. According to the invention, this is achieved by a multi-speed transmission with the features of claim 1.

The combination according to the invention of a rear-wheel derailleur system with a multi-speed planetary gear arranged on the pedal crankshaft surprisingly results in several advantages: With a planetary gear, relatively large differences can be selected between the ratios of the individual gears. These translation differences can be chosen so large that there is no overlap between the individual ratios set via the rear wheel derailleur with the ratios that are achieved in another gear of the planetary gear when setting a specific gear of the planetary gear. Furthermore, the changeover between the individual gears of the planetary gear can be carried out without major lateral displacements of the chain in the area of the pedal crankshaft. It is therefore possible to select all rear sprockets for all gears of the planetary gear transmission by means of the rear wheel derailleur gears, without this leading to an impermissibly strong skewing of the

Chain is coming. In total, a larger number of gears are used. provided as in conventional multi-speed transmissions for bicycles, which have both a rear wheel derailleur and a derailleur in the area of the pedal crankshaft.

The transmission range of the multi-speed transmission can thereby be expanded or finer gradations of the individual translations can be achieved in a predetermined range. If the differences in the sizes of the individual front sprockets are too great, however, the chain could no longer be thrown between the individual sprockets in the conventional front derailleur. Even with the transmission differences used up to now, the exact throwing over of the chain between the front sprockets causes problems and often leads to the chain jumping out, while throwing over the chain between the rear sprockets is comparatively exactly possible.

Furthermore, in the multi-speed transmission according to the invention, a more logical sequence of the individual gears can be achieved for the user. Those gears with the largest gear ratio are set at the highest gear ratio of the multi-speed planetary gear (the rear gear is optional), those gears with the medium gear ratio at the medium gear ratio of the planetary gear and also the gears with the lowest gear ratio at the smallest gear ratio of the planetary gear. These areas overlap in conventional multi-speed transmissions for bicycles.

Furthermore, the chain tensioner in the area of the rear-wheel derailleur in the multi-speed transmission according to the invention has to accommodate less large differences in the "free chain length" between the chain wheels. This difference in length to be recorded by the chain tensioner also limits the maximum transmission range in a conventional multi-speed derailleur system. The design effort for such chain tensioners, which absorb a large difference in length, is also considerable.

In the multi-speed transmission according to the invention, the front sprocket advantageously forms the planet carrier. In a preferred embodiment of the invention, a sun gear rotatably mounted on the pedal crankshaft is provided which can be firmly connected by means of a switching device in a first switching position to a part rigidly connected to the bicycle frame and in a two th switching position is rotatably connected to the crankshaft. This enables a simple design of the planetary gear and the switching device for switching between the individual gears.

The transmission according to the invention also enables shifting while stationary, without moving the pedal crank. If the user has come to a standstill without having changed from a heavy gear to an easy gear, he can therefore switch to an easy gear to start off.

Further advantages and details of the invention are explained below with reference to the accompanying drawings. In this show:

Figures 1 to 3 are schematic representations of an embodiment of a multi-speed transmission according to the invention with schematic sectional views of the planetary gear in the different switching positions;

4 shows a schematic sectional illustration of a further exemplary embodiment of the invention, and FIG. 5 shows a section along the line AA from FIG. 4.

The rear wheel derailleur is designed in a conventional manner and is not shown in detail in the figures. A plurality of rear sprockets or chain wheels 10 are provided, which are connected to the rear wheel hub (via a freewheel). By means of a chain thrower (not shown in FIGS. 1 to 3) and a traction means pivoting the chain thrower, the drive chain 9 is thrown from one rear sprocket 10 of the sprocket set to another.

The pedals 6 are connected via pedal cranks 7 to a pedal crankshaft 8 mounted in a pedal crank bearing 5. The pedal crankshaft 8 stands with a front sprocket 4, over which the drive chain 9 runs, via a multi-speed

Planetary gear 11 in connection. On the pedal crankshaft 8, a sun gear 1, which has spur gear teeth, is rotatably mounted. The sun gear meshes with planet gears 2, which also have spur gears, which are each rotatably mounted on the front sprocket, which forms a planet gear carrier. For example, six such planet gears 2 surrounding the sun gear can be provided. Furthermore, an outer wheel 3 is provided, which has an internal toothing which meshes with the planet wheels 2. In the first switching position of the planetary gear 11 shown in FIG. 1, the sun gear 1 is connected in a rotationally fixed manner to the pedal crank bearing 5, which forms a part rigidly connected to the bicycle frame (a part 12 of which is shown in FIGS. 1 to 3) , This rotationally fixed connection of the sun gear 1 with the pedal crank bearing 5 can be achieved, for example, by toothing on the two abutting side surfaces of these parts. For example, spring-loaded pins, which in the prestressed end position can project over the side surface of the pedal crank bearing, could also be provided, which pins can snap into corresponding recesses in the side surface of the sun gear 1. Furthermore, in this first switching position of the planetary gear, the outer wheel 3 is rotatably connected to the pedal crankshaft 8. For this purpose, a part 13, which is arranged on the pedal crankshaft 8 in a rotationally fixed manner, is provided, which has an external toothing 14 which is brought into engagement with an internal toothing 15 on the outer wheel 3 which meshes with this external toothing in FIG. 1. The rotationally fixed connection between the outer wheel 3 and the pedal crankshaft 8 could also take place in a different manner, as has been explained, for example, in connection with the rotationally fixed connection between the sun wheel 1 and the pedal crank bearing 5. The power transmission thus takes place in this first switching position from the pedal crankshaft via part 13 to the outer gear 3 and further to the planet gears 2. The sun gear 1 is stopped or blocked.

In the second switching position shown in FIG. 2, the sun gear 1 together with the planet gears 2, the front sprocket 4 and the outer gear 3 have been shifted laterally in the direction of the arrow 16. As a result, the rotationally fixed connection between the sun gear 1 and the pedal crank bearing 5 has been opened and a rotationally fixed connection between the sun gear 1 and the pedal crankshaft 8 has been established. For this purpose, the sun gear 1 has been connected in a rotationally fixed manner to the part 13, for example in the manner described in connection with the rotationally fixed connection between the sun gear 1 and the pedal crank bearing 5. Furthermore, the non-rotating connection between the outer wheel 3 and the pedal crank shaft 8 has been released, whereby the external toothing 14 of the part 13 has been disengaged from the internal toothing 15 of the outer wheel 3. The outer wheel is now non-rotatably connected to a part 17 rigidly connected to the bicycle frame 12. For this purpose, an internal toothing 18 is provided on part 17, for example, in this axial position of the outer wheel 3 is in engagement with the external toothing 19 on the outer wheel 3. The outer wheel 3 is thus stopped or blocked and the power transmission takes place from the pedal crankshaft 8 via the part 13 to the sun wheel 1 and further to the planet wheels 2.

3, the sun gear 1 is in the position shifted to the left and the outer gear 3 (together with the front sprocket 4 and the planet gears 2) in the position shifted to the right. Both the sun gear 1 and the outer gear 3 are therefore connected to the pedal crankshaft 8 in a rotationally fixed manner. The power transmission takes place via the outer wheel 3 and the sun wheel 1 to the planet wheels 2.

The first gear position corresponds to the medium gear ratio, while the second gear position represents a light gear ratio and the third gear position represents a heavy gear ratio. In the third shift position, the transmission ratio between the pedal crankshaft 8 and the front sprocket 4 is 1: 1.

The switching device for changing the Schaltstellungeπ the planetary gear 11 is thus in the embodiment shown by the displaceable mounting of the sun gear 1 and the front sprocket 4 together with the planet gears 2 and the outer gear 3 and further by the elements for the rotational connection of the sun gear 1 and of the outer wheel 3 with the bicycle frame 12 or the pedal crankshaft 8 and formed by traction means, not shown in the figures. The distance by which the front sprocket 4 is displaced can be relatively short, so that the drive chain 9 is not displaced substantially relative to the central position with respect to the rear sprocket set formed by the sprockets 10.

In the exemplary embodiment according to FIGS. 4 and 5, the planet gears 2 are not rotatably mounted directly on the front chain ring 4, but on the two guide disks 20 which are arranged on both sides next to the chain wheel. For this purpose, the guide letters 20 have axes 22 connecting them, on which the planet gears 2 are rotatably mounted. 5 shows three such planet gears. Another number of such planet gears could also be provided, for example six. The guide disks 20 are rotatably mounted on the sun gear 1, namely on two lateral shoulders 21 of the sun nenrades that connect laterally to the spur-toothed area of the sun gear and can have a reduced diameter compared to this. A rolling bearing, for example ball bearings, can be provided in each case for mounting the guide disks 20. In the area between the planet gears 2, the guide disks 20 are connected to the chain wheel 4 by means of bolts 23, so that the chain wheel 4 forms a stable unit with the guide disks 20, which represents the planet gear carrier of the planetary gear. The sprocket 4 has a central opening 24 through which the sun gear 1 passes. At the edge of this central opening 24 there are recesses 28 through which the planet wheels 2 run.

In this exemplary embodiment, two outer wheels 3 are also provided, which are arranged on both sides of the chain wheel 4 and each have an internal toothing which meshes with the planet wheels 2. The outer diameter of the guide disks 20 is somewhat larger than the inner diameter of the outer wheels 3 and the outer wheels 3 are thus guided in the area between the guide disks 20 and the chain wheel 4.

4 shows the first shift position of the transmission, in which the sun gear 1 is connected in a rotationally fixed manner to the pedal crank bearing 5, specifically by means of toothing 25 on the two side surfaces of these parts which abut one another. In this first switching position, the outer wheels 3 are connected in a rotationally fixed manner to the pedal crankshaft 8, in a manner analogous to that in the exemplary embodiment shown in FIGS an internal toothing 15 is brought into engagement on an extension on one of the outer wheels 3, as a result of which a type of driver is formed for the two outer wheels 3 (the two outer wheels 3 always rotate synchronously with one another).

In this exemplary embodiment, the sun gear 1, the sprocket 4 with the guide disks 20, the planet gears 2 and the outer gears 3 form a compact and mutually guided unit which is slidably mounted on the pedal crankshaft 8.

By shifting this unit to the left in Fig. 4, the teeth 25 disengage and the teeth 26, 27, which on the facing side surfaces of the part 13 and the sun gear 1 (or its left Shoulder 21) are formed, come into engagement. The rotationally fixed connection of the part 13 to the outer wheels 3 remains here for the time being. This state, when both the sun gear 1 and the outer wheels 3 are connected to the pedal crankshaft 8 in a rotationally fixed manner, corresponds to the third gearshift position of the transmission (shown in the first exemplary embodiment in FIG. 3).

If the sun gear with the parts carried by it are moved all the way to the left in FIG. 4, the toothings 26, 27 are pushed further into one another and the rotationally fixed connection between the part 13 and the outer wheels is released. The inner toothing 18 of the frame-fixed part 17 engages with the outer toothing 19 on the extension of the right outer wheel 3, as a result of which the outer wheels are stopped and the second shift position of the transmission is assumed (corresponding to FIG. 2 of the first exemplary embodiment).

Different variations of the planetary gear 11 are conceivable and possible, as are known in such planetary gears, without leaving the scope of the invention. In each case, a planetary gear transmission is combined with a rear-wheel derailleur in the area of the pedal crankshaft. The planetary gear mechanism can also be designed to switch between more than three gears. Such planetary gears are known in different designs.

L e g e n to the reference number i:

Sun gear 20 guide disc

Planetary gear 21 shoulder

Outer gear 22 axle front sprocket 23 bolts

Pedal crank bearing 24 opening

Pedal 25 toothing

Pedal crank 26 toothing

Pedal crankshaft 27 toothing

Drive chain 28 Rear sprocket recess

Multi-speed planetary gear

bicycle frame

part

external teeth

internal gearing

arrow

part

internal gearing

external teeth

Claims

claims:

1. Multi-speed transmission for bicycles with a rear wheel derailleur, elche several rear sprockets connected to the rear wheel hub and a chain thrower for throwing the drive chain from one rear sprocket to another, characterized in that the pedal crankshaft (8) driven by the pedal cranks (7) ) with a front sprocket (4), over which the drive chain (9) runs, over a multiple shift positions to change the gear ratio between the pedal crankshaft (8) and the sprocket (4), which can be selectively inserted by means of a switching device, multi-speed Planetary gear (11) is connected.

2. Multi-speed transmission according to claim 1, characterized in that the multi-speed planetary gear (11) has a rotatably mounted sun gear (1), at least one, preferably at least three, on a planet gear carrier rotatably mounted planet gears (2) which with the sun gear (1) Comb, and a rotatably mounted outer wheel (3), which meshes with the planet gears (2), comprises that for inserting a first switching position by means of the switching device, the sun wheel (1) is rotatably connected to a part rigidly connected to the bicycle frame (12) and for inserting another switching position by means of the switching device, the sun gear (1) can be connected in a rotationally fixed manner to the pedal crankshaft (8), and in these two switching positions there is a rotationally fixed connection of the outer wheel (3) to the pedal crankshaft (8), and that for Insert a further switching position by means of the switching device, the non-rotatable connection between the outer wheel (3) and the pedal crankshaft (8) l sbar and the external gear (3) rotationally fixed with egg nem to the bicycle frame (12) rigidly connected part is connected and the sun gear (1) in rotation with the pedal crankshaft (8) is connectable.

3. Multi-speed transmission according to claim 1 or claim 2, characterized in that the switching device in the axial direction of the pedal crankshaft (8) displaceable mounting of the sun gear (1) and the front sprocket (4) together with the planet gears (2) and the at least one Includes outer wheel (3).

4. Multi-speed transmission according to claim 3, characterized in that the front sprocket (4), the sun gear (1), the planet gears (2) and the one or more outer wheels (3) form an overall displaceable unit in the axial direction of the pedal crankshaft (8) ,

5- multi-speed transmission according to one of claims 1 to 4, characterized in that the planet gears (2) on the front sprocket (4) are rotatably mounted.

6. Multi-speed transmission according to one of claims 1 to 4, characterized in that the planet gears are rotatably mounted on guide disks (20) which are arranged on both sides of the sprocket and are rotatably connected to the sprocket.

7. Multi-speed transmission according to one of claims 1 to 6, characterized in that two outer wheels (3) arranged on both sides of the chain wheel (4) are provided, preferably the chain wheel (4) being provided in recesses of the same penetrating planet wheels (2).

8. Multi-speed transmission according to claim 6 or claim 7, characterized in that the guide disks (20) are rotatably mounted on shoulders (21) of the sun gear (1), which connect laterally to its spur-toothed area, preferably via a roller bearing.

9. Multi-speed transmission according to one of claims 6 to 8, characterized in that the outer diameter of the guide plates (20) is larger than the inner diameter of the outer wheels (3), the outer wheels (3) in the region between the guide plates (20) and the sprocket (4) are arranged.

10. Multi-speed transmission according to one of claims 6 to 9, characterized in that the chain wheel has a central opening (24) which is penetrated by the sun gear (1).

1 1. Multi-speed transmission according to claim 10, characterized in that in the edge of the central opening (24) of the chain wheel (4) recesses (28) are provided which are penetrated by the planet gears (2).

12. Multi-speed transmission according to one of claims 7 to 11, characterized in that the guide disks (20) are connected to the chain wheel (4) via bolts (23) lying in the region between the planet wheels (2).