GB2093780A - Transmission for vehicles having two power sources - Google Patents

Abstract

A vehicle, having a driven wheel, includes two independently operable free wheel arrangements, both of which are arranged to transmit drive to the wheel in the same direction. The vehicle may be a bicycle, in which the conventional pedal drive is transmitted to one of said free wheels via a chain, and in which a prime mover, e.g. an electric motor driven by a battery, is mounted on the bicycle to drive the other free wheel via an endless chain.

Description

SPECIFICATION improvements in or relating to vehicles This invention relates to vehicles and more specifically to a vehicle intended to be driven by one or the other of two power sources, or by both power sources simultaneously.

It is well known in the art to provide manually driven vehicles, such as invalid carriages, bicycles and the like hand lever or pedal actuated vehicles, with a prime mover, such as an internal combustion engine or a mains or battery operated electric motor, and a clutch device for selectively engaging and disengaging the drive from the prime mover.

In the cycle art it is known to build an internal combustion engine into the rear wheel of a bicycle, drive a road wheel of the bicycle via an internal combustion engine acting through a roller engaged with the tyre of the driven road wheel and, in more recent years, it has been proposed to apply the drive from a battery driven electric motor to the conventional chain drive for the bicycle.The construction wherein the engine is built into a road wheel of the bicycle met with a degree of success, the arrangement whereby the drive from the prime mover was applied to the tyre of the vehicle suffered from the defect that tyre wear was greatly increased and, when the power drive is to the conventional chain, the pedal drive is always rotated by the power driven chain and if both power and manual drives are applied the chain can be overloaded and fail, to render both the power and manual drive inoperable.

The present invention seeks to provide a wheel for a vehicle capable of accepting a conventional manual drive and drive from a prime mover and whereby the two drives can be applied alternatively or simultaneously to the wheel.

According to the present invention there is provided a wheel for a vehicle, said wheel including two independently operable free wheel arrangements both of which are arranged to transmit drive in the same direction.

Preferably the two free wheels are arranged on opposite sides of the wheel.

Preferably the wheel comprises a road wheel for the vehicle.

In a preferred embodiment said wheel comprises the rear wheel of a bicycle, the conventional pedal drive is transmitted to one of said free wheels via a conventional pedal chain, and a prime mover mounted on the bicycle drives the other free wheel via an endless chain.

It will thus be seen that with the arrangement proposed by the present invention, and with the prime mover inoperable, the bicycle can be driven in conventional manner via the pedal drive arrangement, when the prime mover is operating and transmitting drive to its free wheel the pedals may be held in a relatively stationary position with respect to the vehicle frame so that the drive is wholly from the prime mover, and in a further mode of operation the prime mover and the pedal drive may both transmit drive to the wheel via their independent free wheels.

Preferably the prime mover comprises an electric motor driven by a battery and said motor and battery are mounted on a rack or frame adjacent the rear wheel of the vehicle.

The invention will now be described further by way of example with reference to the accompanying drawings in which: Fig. 1 shows a side view of a bicycle in accordance with the invention.

Fig. 2 shows an opposite side view of the rear part of the vehicle and, Fig. 3 shows a rear view of the rear wheel of the bicycle.

The bicycle illustrated in the drawings is basically of a conventional construction and comprises a frame, generally indicated by reference numeral 1 with handle bars 12 and a seat 1 3 upstanding therefrom, front and rear wheels 14 and 1 5 respectively, and a conventional pedal drive 1 6 the rotation of which clockwise, as viewed in Fig. 1, is transmitted by an endless chain 17 to a free wheel 18 on the rear wheel 1 5. The frame 11 includes a platform 1 a over the rear wheel, similar to, or identical with, the conventional luggage platform well known in the cycle art.

The illustrated bicycle differs from conventional bicycles in that the rear wheel 1 5 includes additional to the conventional free wheel 1 8 a free wheel 19, on the opposite side of the wheel 1 5 to the free wheel 18, and the free wheel 1 9 is arranged to transmit drive in the same direction as the free wheel 18, that is to say both free wheels 1 8 and 19 transmit drive clockwise as viewed in Fig. 1.

A prime mover convenientiy comprising a battery operated electric motor 20, is mounted on the platform 1 a and presents a drive shaft 21 upon which a chain wheel 22 is secured. An endless chain 23 passes over the chain wheel 22 and the free wheel 1 9 and whereby drive can be transmitted from the prime mover 20 to the free wheel 19.

It will now be appreciated that, with the above described arrangement, and with the electric motor 20 disconnected from its power source (the battery) the cycle can be ridden with the manual drive effective, by rotating the pedal drive 1 6 clockwise as viewed in Fig. 1. Rotation of the pedal drive 1 6 clockwise, as viewed in Fig. 1 , is transmitted via endless chain 1 7 to the free wheel 1 8 which, in rotating clockwise, transmits drive to the rear wheel 1 5. As the electric motor 20 is static the chain 23 is stationary and the clockwise rotation of rear wheel 1 5 causes the free wheel 1 9 to slip so that the only retarding force acting on the vehicle is that required to slip the free wheel 1 9.

When now power is extended to the motor 20 to cause said motor 20 to operate, drive from the motor 20 is transmitted through chain wheel 22 and endless chain 23 to the free wheel 19, the direction of drive is such that the sprocket wheel on free wheel 1 9 is rotated clockwise (as viewed in Fig. 1) so that clockwise rotation is transmitted to the rear wheel 1 5 and, with such drive effective, the pedal drive 1 6 can be held stationary relative to the frame 11 and the only retarding force exerted by the manual drive is that required to allow the free wheel 18 to slip.

When the motor 20 is driving the rear wheel 1 5 the rider can rotate the pedal drive 16 in the clockwise direction but such rotation will be ineffective on the drive until the rotation imparted to free wheel 18 by chain 17 exceeds the rotation speed of the free wheel 19. That point at which the rotational speed of free wheel 18 is just sufficient to transmit drive to the rear wheel 1 5 is the tower limit for combined power and manual drive to the rear wheel 15.

If now, from the lower limit for combined power and manual drive, the rider increases the rotational speed of pedal drive 16, to increase the rotational speed of free wheel 18, said free wheel will transmit drive to the rear wheel 1 5, such drive will reduce the load on motor 20 and, with reduced load, the speed of motor 20 will increase so that the free wheels 18 and 19 will rotate at the same speed and both free wheels 18 and 1 9 will transmit drive to rear wheel 1 5. The faster the free wheel 1 8 is rotated the greater will be the proportion of the drive imparted to wheel 15 by the manual drive and the drive from motor 20 will proportionally reduce until, at that speed at which motor 20 is rotating without a load, the drive is wholly manual and the drive passes above the upper limit for combined power and manual drive.

Preferably the speed of motor 20 without load is such that the upper limit for combined power and manual drive can only be achieved when the vehicle is travelling down a severe incline when the forward speed of the vehicle, due two its momentum, would normally over-ride the conventional pedal drive arrangement.

Although not illustrated in the drawings it is obvious that the pedal drive 1 6 may drive rear wheel 1 5 via a conventional differentiai speed gearing so that, under manual drive, the rotational speed of rear wheel 1 5 relative to the rotational speed of the pedal drive 1 6 can be selectively varied. in like manner, the drive from motor 20 may be via a selective gearing to the chain wheel 22 or the drive from the sprocket of free wheel 19 may be via a selective gearing so that, with the power drive effective, the rotational speed of rear wheel 1 5 can be selectively varied with respect to the rotational speed of the output shaft 21 of motor 20.

It will also be appreciated that the bicycle illustrated in Figs. 1 and 2 may be provided with lighting, braking, and the like ancillary equipment, well known in the art, and such apparatus has been omitted from the specific embodiment for clarity in the drawings.

Although the present invention has been described by way of example with reference to a specific embodiment many modifications and variations will be apparent to persons skilled in the art.

Claims (9)

1. A wheel for a vehicle capable of accepting a conventional manual drive and drive from a prime mover and whereby the two drives can be applied alternatively or simultaneously to the wheel, the said wheel including two independently operable free wheel arrangements both of which are arranged to transmit drive in the same direction.

2. A wheel as claimed in claim (1) wherein the said two free wheels are arranged on opposite sides of the wheel or both on either side of the wheel.

3. A wheel as claimed in claims (1) and (2) which comprises a road wheel for the vehicle.

4. A wheel as claimed in claims (1-3) which comprises the rear wheel of a bicycle, the conventional pedal drive is transmitted to one of said free wheels via a conventional pedal chain and a prime mover mounted on the bicycle drives the other free wheel via an endless chain.

5. A wheel as claimed in claim (4) the prime mover of which comprises an electric motor driven by a battery, and said motor and battery are mounted on a rack or frame adjacent to the said wheel.

6. A wheel according to claim (1) as hereinbefore described with reference to the accompanying drawings.

7. A vehicle having a wheel as claimed in claim (1).

8. A bicycle having a wheel as claimed in claims (4-6).

9. A bicycle described with reference to the accompanying drawings.