GB2073683A

GB2073683A - Motor attachment for a cycle

Info

Publication number: GB2073683A
Application number: GB8012380A
Authority: GB
Original assignee: Wallis G L
Current assignee: Wallis G L
Priority date: 1980-04-15
Filing date: 1980-04-15
Publication date: 1981-10-21

Abstract

A motor attachment for a pedal bicycle comprises a framework 10, 11 securable to the bicycle frame at opposite sides of the rear wheel, an internal combustion engine E carried by the framework 10, 11 at one side, a roller 16 driven by the engine E by way of a belt-and-pulley speed- reduction transmission 18, 19 and located above the wheel and parallel to the wheel axle and arranged to bear on the wheel tyre T, and a manually operable lever 14 in a gate 15 and urged by a spring 16 towards the tyre T and operable to bring the roller 16 into and out of engagement with the tyre T. Instead of the single roller 16 there can be provided two rollers in tandem driven at differing speeds and arranged to be alternatily brought into engagement with the tyre T to give two-speed drive. <IMAGE>

Description

SPECIFICATION A drive attachment for a cycle According to one aspect of the present invention, there is provided an attachment for a cycle comprising a framework arranged to be secured to the frame of the cycle at a side of a wheel of the cycle, an internal combustion engine carried by the framework for location at said side, a drive roller driven by the engine and located above the wheel and substantially parallel with the wheel axle and arranged when the attachment has been fitted, to bear on the tread of the wheel tyre, means for bringing said roller into and out of contact with the tyre, and a transmission by way of which said engine drives said roller.

According to another aspect of the present invention, there is provided an attachment for a cycle, comprising a framework arranged to be secured to the frame of the cycle at a side of a wheel of the cycle, an internal combustion engine carried by the framework, a shaft driven by the engine and located above the wheel and substantially parallel with the wheel axle, a beltand-pulley transmission by way of which said engine drives said shaft, a drive roller on said shaft arranged, when the attachment is fitted, to bear on the tread of the wheel tyre, and means for bringing said roller into and out of contact with the tyre.

Owing to the invention, it is possible to provide for a pedal bicycle a drive attachment which is of simple construction, can be fitted easily to standard bicycles, and when fitted results in a machine which is stable and easily controlled.

The attachment preferably comprises a framework, adapted for securing to the frame of a bicycle at opposite sides of the rear wheel, an internal combustion engine carried by the framework at one side, a countershaft driven by the engine and located above the wheel and substantially parallel with the rear wheel axle, a speed-reducing transmission from the engine to the shaft, a drive roller on the countershaft adapted when the attachment is fitted, to bear on the tread of the rear wheel tyre, means for bringing said roller into and out of contact with the tyre, and a fuel tank for engine fuel supply mounted on the framework.

Advantageously, the drive from the engine to the shaft is by a belt-and-pulley arrangement, and a clutch such as a centrifugal clutch is incorporated in the drive. The drive can be by way of a pair of tandem rollers and a gear box for speed change can be incorporated.

The attachment can be fitted to a bicycle easily by removing a portion of the rear mudguard and the framework secured at its lower ends to the rear wheel spindle or the bicycle frame, and to the seat stays at the rear of the frame.

The belt-and-pulley transmission may comprise a lower pulley on the engine crankshaft, and a split pulley on one end of the countershaft, with the sections of the pulley spring loaded towards one another.

The end of the countershaft remote from the pulley preferably is connected to a lever, which lever has a hand holding portion extending to a location convenient for hand manipulation, the arrangement being such that the lever is used to bring the roller into and out of contact with the tyre, the lever being spring loaded on to the tyre.

In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which Figure 1 is a side view of the rear of a bicycle with a motor attachment fitted, Figure 2 is a plan view showing a pulley and shaft arrangement of the attachment, Figure 3 is a rear view of the attachment, and Figure 4 is a plan view of a modified arrangement incorporating a two speed gear change.

Referring first to Figures 1-3, the attachment includes a lightweight metal framework consisting of spaced apart side portions 10, and an upper horizontal platform 11. The lower ends of the side portions are constructed so as to be secured on the ends of the rear wheel spindle of the bicycle, and the platform secured by a strut 1 2 to the frame of the bicycle. One side portion 10 carries a small internal combustion engine E, which has its crankshaft disposed radially iriwards of the tyre T of the rear wheel, in fact nearer to the wheel centre than to the wheel rim. It will be understood that the engine includes carburettor, flywheel, magneto and usual controls. The platform supports a fuel tank F which in turn may carry a basket B. The other side portion may carry a pannier.

The side portions also support a countershaft 13 in appropriate self-aligning bearings. At the side opposite the engine, the bearing is carried by a lever 14 pivoted at one end and passing through a gate 15, terminating in a hand operable portion 1 4a at the other end. The countershaft has fixed thereto a drive roller 1 6. In fitting the attachment, a portion of the rear mudguard of the bicycle is removed. A spring 1 7 pulls the roller onto the tread of the tyre T. The lever can be raised manually to interrupt the drive to the tyre, and locked up in such position by the gate 1 5.

The countershaft 13 carries a split pulley 18 which is coupled to the engine crankshaft by a pulley and V-belt drive 1 9, the one half of the pulley being loaded by a spring 20 towards the other half. Said other half is coupled to an automatic clutch 21 which drives the shaft 1 3.

Since the pulley 18 is of greater diameter than the other pulley of the belt-and-pulley transmission, speed reduction is obtained, which allows use of a faster speed engine, thus giving a better uphill driving capability.

A variable speed gear change can be incorporated.

In the arrangement shown in Figure 4, a gear assembly is provided having two rollers 16, 1 6a arranged in tandem. The gear assembly has two driven gearwheels 22 and 22a fixed to shafts carrying the rollers 1 6 and 1 6a, and a drive gearwheel 23 fixed to the countershaft 13. The gearwheel 22 has the same number of teeth as the gearwheel 23, but the gearwheel 22a has more teeth than the gearwheel 23. In this arrangement, the lever 1 4 and the gate are such that either the one or the other roller can be brought to contact the tyre by tilting the gear assembly/roller support, so giving speed change, or both rollers held out of contact with the tyre.

In the arrangement of Figures 1-3 tandem rollers can be provided to increase the drive on to the tyre.

The attachment described above provides a small easily fitted power unit for a bicycle. The main weight is located close to the centre line of the bicycle and low down at the rear of the bicycle, so that it has little effect on the stability of the bicycle when ridden or on the steering of the bicycle.

Claims

1. An attachment for a cycle comprising a framework arranged to be secured to the frame of the cycle at a side of a wheel of the cycle, an internal combustion engine carried by the framework for location at said side, a drive roller driven by the engine and located above the wheel and substantially parallel with the wheel axle and arranged when the attachment has been fitted, to bear on the tread of the wheel tyre, means for bringing said roller into and out of contact with the tyre, and a transmission by way of which said engine drives said roller.

2. An attachment as claimed in claim 1, wherein said transmission is a speed reduction transmission.

3. An attachment as claimed in claim 1 or 2, wherein said transmission is a belt-and-pulley transmission.

4. An attachment as claimed in any preceding claim, wherein said transmission includes a clutch.

5. An attachment as claimed in claim 4, wherein said clutch is a centrifugal clutch.

6. An attachment as claimed in any preceding claim, and further comprising another drive roller situated in tandem with the first-mentioned roller and arranged, when said attachment has been fitted, to bear on said tread, this other roller also being driven by the engine by way of said transmission and being located above said wheel and substantially parallel with the wheel axle, and said means serving also to bring said other roller into and out of contact with said tyre.

7. An attachment as claimed in claim 6, wherein said first-mentioned roller drives said wheel at a greater speed than does said other roller and is in contact with said tyre when said other roller is out of contact therewith and vice versa.

8. An attachment as claimed in claim 3, or any one of claims 4 to 7 as appended to claim 3, wherein the belt-and-pulley transmission comprises a lower pulley on a crankshaft of the engine, and a split pulley on one end of a countershaft of said transmission, with the sections of the split pulley spring loaded towards each other.

9. An attachment as claimed in any one of claims 1 to 7, wherein a countershaft of said transmission is connected to a lever, which lever has a hand holding portion extending to a location convenient for hand manipulation, the arrangement being such that the lever is used to bring the roller(s) into and out of contact with the tyre.

1 0. An attachment as claimed in any preceding claim, and further comprising a fuel tank for engine fuel supply mounted on said framework.

1 An attachment for a cycle, comprising a framework arranged to be secured to the frame of the cycle at a side of a wheel of the cycle, an internal combustion engine carried by the framework, a shaft driven by the engine and located above the wheel and substantially parallel with the wheel axle, a belt-and-pulley transmission by way of which said engine drives said shaft, a drive roller on said shaft arranged when the attachment is fitted, to bear on the tread of the wheel tyre, and means for bringing said roller into and out of contact with the tyre.

12. An attachment as claimed in claim 11, wherein said transmission is a speed reduction transmission.

13. An attachment as claimed in claim 11 or 12, wherein said transmission is a belt-and-pulley transmission.

14. An attachment as claimed in any one of claims 11 to 13, wherein said transmission includes a clutch.

1 5. An attachment as claimed in claim 14, wherein said clutch is a centrifugal clutch.

16. An attachment as claimed in any one of claims 11 to 15, and further comprising another drive roller situated in tandem with the firstmentioned roller and arranged, when said attachment has been fitted, to bear on said tread, this other roller also being driven by the engine by way of said transmission and being located above said wheel and substantially parallel with the wheel axle, and said means serving also to bring said other roller into and out of contact with said tyre.

1 7. An attachment as claimed in claim 16, wherein said first-mentioned roller drives said wheel at a greater speed than does said other roller and is in contact with said tyre when said other roller is out of contact therewith and viceversa,

18. An attachment as claimed in claim 13 or any one of claims 14 to 1 7 as appended to claim 13, wherein the belt-and-pulley transmission comprises a lower pulley on a crankshaft of the engine crank, and a split pulley on one end of a countershaft of said transmission, with the sections of the split pulley spring loaded towards each other.

19. An attachment as claimed in any one of claims 11 to 17, wherein a countershaft of said transmission is connected to a lever, which lever has a hand holding portion extending to a location convenient for hand manipulation, the arrangment being such that the lever is used to bring the roller(s) into and out of contact with the tyre.

20. An attachment as claimed in any one of claims 11 to 19, and further comprising a fuel tank for engine fuel supply mounted on said framework.

21. An attachment for a cycle, substantially as hereinbefore described with reference to Figs. 1 to 3, or Figs. 1 to 3 as modfied by Fig. 4 of the accompanying drawings.