GB2320069A

GB2320069A - Bicycle rear-axle change-speed layshaft gearing

Info

Publication number: GB2320069A
Application number: GB9725235A
Authority: GB
Inventors: Yun-Liu Liu
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-12-06
Filing date: 1997-12-01
Publication date: 1998-06-10
Anticipated expiration: 2017-12-01
Also published as: ITTO970238V0; GB9725235D0; ITTO970238U1; CN2264137Y; DE29721531U1; IT236364Y1; GB2320069B; FR2756805A3; FR2756805B3

Abstract

A layshaft change-speed gear at the rear wheel of a bicycle comprises an input set of gears 2, driven by a freewheel sprocket 17, in engagement with gears 3 which can be selectively coupled to the layshaft 12 which in turn drives the wheel through selectable gears 4 and output gears 5. Gears of the gearsets 3 and 4 are coupled to the layshaft 12 by radially-acting balls 14 operated by axially-moved cams. In an alternative embodiment the gears 3 and 4 are fixed to the layshaft and the gears 2 and 5 selectively coupled to the input and output shafts 16, 23 respectively (Figs 4 and 5). The freewheel sprocket may be to one side of the gearing instead of centrally positioned as shown.

Description

2320069 A BACK-SHAFT SPEED CHANGER OF BICYCLE

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a back-shaft speed changer of bicycle, 5 and more particularly to aTear wheel gear change device of bicycle.

1 Description of Prior Art

In accordance with the conventional the back-shaft speed changer of bicycle, it consists of several gears mounting on the back-shaft between the both blades of hub, and several planetary gears round the gears, and two io catch reversing gears built on the both ends of planetary gear sets; by changing the transmission route, the speed is changed. It includes a rear axle, several sun gears, several planetary gears, right and left ratchets. But the adjusting range of this kind of changing speed mechanism is so narrow that it can not stand great load, and it is inconvenience for repair operation.

1 OBJECTS AND SUMMARY OF THE INVENTION

It is therefore a main object of the present invention to provide a rear wheel gear change device with a wider adjusting range for standing greater load, and easier operation with lower failure rate and longer service life.

This object is achieved by a gear change mechanism comprising sev eral cluster gears and gear housing, which is attached on the back-shaft, therein two cluster gears A and D are mounted on the rear axle, and a lay shaft paralleling the rear axle attaches on two cluster gears B and C coordinating to the cluster gears A and D. Wherein the cluster gear A is stuck over the free io wheel axle to link the free wheel up, and the cluster gear D is linked to the hub via the output axle, and both said free wheel and output axles are installed on the rear axle of bicycle. The cluster gears B and C mounting on the lay shaft mesh with the cluster gears A and D one to one correspondingly and respec tively. Every couple of the co-ordinating cluster gears must have one having is more than one notch housing part of steel ball built upon the inside surface of the inside hole, and mounting on a hollow shaft on which several holes are bored in division co-ordinating to the notches of the inside hole of the cluster gear; every equation hole of the hollow shaft contains a steel ball, and a con trollable cam with slants is installed into the hollow shaft.

Basing on the above-described mechanism, two operations can be de veloped as the controller device, including the steel balls, the hollow shaft with the slant cam, and the notches of the cluster gears, can be built on not only the lay shaft as the first operation, but also the rear axle as the second operation.

Regarding to the slant cam in the present invention, it is formed to a short shoulder with both bevelled sides,, and there are two slant cams built on 2 the proper positions. Said cluster gears can be mounted on the one side of the hub or between the both blades of hub.

The connecting interfaces of the two half gear housings is on the flat decided by both central lines of the rear axle and lay shaft, and the gear hous- ing is fixed on the back-shaft with screws, and connecting to the chain stays through a pivot. The gear housing also can be designed into a retaining recess integrated with the rear wheel, and having a side cap cover on it from one side. In this way, the rim and the wheel shroud can be integrated together.

In practising, by means of changing the positions of the slant cams in io the hollow shaft to catch at different balls, the working engaging gears can be changed in the co-ordinating cluster gears to meet the speed change goal.

3 BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side view showing the installation of the present invention; Fig. 2 is a topside view of Fig. 1; Fig. 3 is a cross-section view showing the first operation of the present invention; Fig. 3a is an exploded view showing the back-shaft of Fig. 3; Fig. 3b is an exploded view showing the lay shaft of Fig. 3; Fig. 4 is a cross-section view showing the second operation of the present invention; Fig. 5 is a cross-section view showing the third operation of the present invention; Fig. 6 is a part cross-section view showing the present invention combining with a coaster brake; Fig. 7 is a cross-section view showing the A-A section of Fig. 3; Fig. 8 is a cross-section view showing the B-B section of Fig. 3.

Fig. 9 is a cross-section view showing the C-C section of Fig. 4; is 4 DETAILED DESCRIPTION OF PRIFERRED EMBODIMENTS

Referring to Fig. 1 and Fig. 2, the present invention provides a backshaft speed changer 7 of bicycle mounted on the back-shaft 1. The relative parts are shown on drawings like the free wheel 17, the chain wheel 11, the s chain stays 10, the rear wheel 6 and the spokes 8.

Fig. 3 is showing the first operation, co-operating with referring to Fig. 3a and Fig. 3b, the speed changer includes two cluster gears, cluster gears A 2 and cluster gears D 5, mounting on the back-shaft 1, and two cluster gears, cluster gears B 3 and cluster gears C 4, mounting on the lay shaft 12 parallel- io ing the back-shaft 1, wherein the cluster gears A, B, Q and D are shown on drawings as 2, 3, 4, and 5; the numbers of the gears included in the cluster gears B 3 and cluster gears C 4 are same as in the cluster gears A 2 and cluster gears D 5 correspondingly, as shown on Fig. 3, the cluster gears A 2 and cluster gears B 3 include three gears separately, and the cluster gears C 4 and cluster gears D 5 include two gears separately, and they mounting on the separated two shafts are all engaging with the corresponding one respectively. The cluster gear A 2 is fixed on the free wheel shaft 16, and the cluster gear D 5 is linked to the blade 18 of the hub via the pawl 20 and the ratchet wheel 2 1. The cluster gears B 3 and cluster gears C 4 putting on the lay shaft 12 have one or more notches holding a part of steel ball on the wall surface of the inner hole of every gear, referring to Fig. 7. The lay shaft 12 is hollow shaft that is bored fifteen equation holes at the corresponding positions to the cluster gears installing on it, in which every equation hole contains a steel ball 14 or steel post. In the hollow inside of the lay shaft 12 two controllable slant cams 13 are installed, and the slant earn 13 is made into a short shoulder with both bevelled sides, on the top surface of the slant earn 13 several shallow recesses for seating the steel ball or steel post are formed (not shown in the drawings), said two slant cams 13 are controlled by triggers on the handlebar via cable and control level 29 separately, a spring 28 is installed on the one end of every slant cam 13 for restoring the original position to co-operate with the trigger so as to locate the desired steel balls 14 on the hollow lay shaft into the notches of the gear of the cluster gear. Due to the gear changer setting on one side of the blades 18 and 19, the connecting interfaces of the two half gear housings 15 is on the flat decided by both central lines of the back-shaft 1 and lay shaft 12, and the gear housing 15 is fixed on the back-shaft 1 with screws, io and connected to the chain stays through a pivot. In this operation. the cluster gears A 2 and cluster gears B 3 have three couples of engaging gears, the cluster gears C 4 and cluster gears D 5 have two couples of engaging gears, therefore the number of gear-change is six (2 x 3=6), if adding or removing is the number of the engaging gears, the gear-change is increased or decreased. In practising, the cluster gear A 2 is driven by the chain wheel 11 via the chain and the free wheel 17, and brings along the gear caught at by the steel ball 14 in the cluster gear B 3 to transfer the torsion, via the gear of cluster gear C 4 caught at by the steel ball 14, the cluster gear D 5 is driven, meanwhile the torsion is transferred to the blade 18 through the pawl 20 and the ratchet 21, refemng to Fig. 8, to rotate the rear wheel forward.

Referring to Fig. 4, it is the second operation of the present invention. the speed changer includes cluster gear A 2 and cluster gear D 5 mounting on the back-shaft 1, and cluster gear B 3 and cluster gear C 4 mounting on the lay shaft 12 paralleling the back-shaft 1, wherein the numbers of the gears included in the cluster gear B 3 and cluster gear C 4 are same as in the cluster gear A 2 and cluster gear D 5, and they mounting on the separated two shafts are all engaging with the corresponding one respectively. All the parts of the 6 speed changer are located on middle of the back-shaft between the both blades 18 and 19. The cluster gear A 2 and cluster gear D 5 with notches on the inner holes as above-described are installed on the hollow free wheel shaft 16 and the hollow output shaft 23 respectively. Said hollow free wheel shaft 16 and the hollow output shaft 23 are bored twelve equation holes in which a steel ball 14 or steel post is contained respectively, and two slant cams 13 are put into the inside separately. The working principle of this mechanism is almost same with above in Fig. 3, the cluster gear A 2 is driven by the chain wheel 11 via the chain and the free wheel 17, and brings along the cluster io gears B 3 and cluster gears C 4 to transfer the torsion to the cluster gear D 5, meanwhile the torsion is transferred to output shaft 23, referring to Fig. 8, to rotate the side cap 22, because the side cap 22 is fixed on the gear housing 15 that is integrated with the both blades 18 and 19 in a whole body. the rear wheel 6 is rotated forward. In this operation, by moving the positions of the is two slant cams 13 in the back-shaft 1, the speed is changed; the slant cams 13 is controlled by the control level 29 via a push bars 26 co- operating with the end springs 28; a tie strap 33 is mounted between the two couples of engaging cluster gears to keep the centre distance between the back-shaft 1 and the lay shaft 12; regarding to the free wheel, it can be employed a standard product integrating with the pawl and ratchet to reduce the production and installation parts. Due to the gear housing and the hub being a whole body, the lay shaft 12 rotates around the back-shaft 1 as running.

The speed change mechanism shown on Fig. 5 is same as shown on Fig. 4, but the main difference is on the structure of the rear wheel,, the gear housing is integrated with the rear wheel, so the back-shaft formed a retaining recess 27 and a side cap 22, the speed change mechanism can be installed 7 and enclosed in it. This structure is prefer applied to the BMX or foldable bicycle especially.

The speed change mechanism shown on Fig. 6 is to integrate the structure shown on Fig. 3 and a coaster brake 30, which is especially applied to the short wheel centre distance and small wheel bicycle. In the drawing, all the parts mounting on the back-shaft are installed on a steel tube 31 fixed by a nut 32 for assembling these parts into an assembly so as to be convenience of installation and 'dismount.

Fig. 7 is a part, cross'section view showing the notches of the inner hole io of the gear, in which there are six notches formed on the inside wall of the gear, co-ordinating to them, there are three steel balls held in the hollow lay shaft 12. The number of the notches is just multiple of the number of the steel balls. On the other hand, the shape of the notch can be in section of a circle or other shapes. Fig. 8 is a part cross- section view showing the ratchet; the i s bearings of the back-shaft 1 and the output shaft 23 shown on drawings can be selected to needle bearings.

8 1 1 claim:

is 1. A back-shaft speed changer of bicycle including several cluster gears and gear housing, wherein, the speed changer includes two cluster gears A and D mounting on the back-shaft, and two cluster gears B and C mounting on the lay shaft paralleling the back-shaft; therein, the cluster gear A is fixed on the free wheel shaft, and the cluster gear D is linked to the hub via an output shaft, the free wheel shaft and the output shaft are installed on the backshaft; the numbers of the gears included in the cluster gears B and C are same as in the cluster gears A and D correspondingly, and they are all engaging with the corresponding one respectively; every couple of the co-ordinating cluster gears must have one having more than one notch housing part of steel ball built upon the inside surface of the inside hole of per gear, and mounting on a hollow shaft on which several holes are bored in division co-ordinating to the notches of the inside hole of the cluster gear; every equation hole of the hollow shaft contains a steel ball, and a controllable cam with slants is installed into the hollow shaft.

2. A back-shaft speed changer of bicycle as claimed in claim 1, wherein,, the cluster gears B and C putting on the lay shaft have one or more notches housing a part of steel ball on the wall surface of the inner hole of every gear; the lay shaft is hollow shaft that is bored several equation holes at the corresponding positions to notches of the cluster gears installing on it, in which every equation hole contains a steel ball or steel post in the hollow inside of the lay shaft two controllable slant cams are installed.

3. A back-shaft speed changer of bicycle as claimed in claim 1, wherein, a hollow free wheel shaft and a hollow output shaft are installed on the back-shak the cluster gears A and D with notches on the inner holes are 9 1 installed on the hollow firee wheel shaft and the hollow output shaft respec tively, the hollow free wheel shaft and the hollow output shaft are bored proper number equation holes in which a steel ball is contained respectively, and two slant cams are put into the inside separately.

4. A back-shaft speed changer of bicycle as claimed in claim 1, wherein, the slant cam is made into a short shoulder with both bevelled sides.

5. A back-shaft speed changer of bicycle as claimed in claim 1, wherein, the number of the slant cams is two.

6. A back-shaft speed changer of bicycle as claimed in claim 1, io wherein, the assembly of the all parts of the back-shaft speed changer is in stalled on one side of the hub.

7. A back-shaft speed changer of bicycle as claimed in claim 1, wherein, the assembly of the all parts of the back-shaft speed changer is in stalled on middle of the back-shaft between the both blades of hub.

8. A back-shaft speed changer of bicycle as claimed in claim 1 and claim 6, wherein, the connecting interfaces of the two half gear housings is on the flat decided by both central lines of the back-shaft and lay shaft, and the gear housing is fixed on the back-shaft with screws, and connected to the level chain stays through a pivot.

9. A back-shaft speed changer of bicycle as claimed in claim 1 and claim 7, wherein, the gear housing integrated with the rear wheel and the back-shaft formed a retaining recess to install the speed change mechanism in, and enclosed by the side cap.

is