GB2164615A

GB2164615A - Transmission device assembly for vehicle

Info

Publication number: GB2164615A
Application number: GB08424020A
Authority: GB
Inventors: Felice Campopiano
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-09-21
Filing date: 1984-09-21
Publication date: 1986-03-26
Also published as: GB8424020D0

Abstract

A transmission drive assembly for an electrically assisted or powered vehicle e.g. a bicycle, comprises a drive plate 1 and adaptor gear 4. This assembly is located on the outer casing of a change-speed gear hub 3 fitted to a wheel 2 by means of location using its three inner teeth and held in position by a circlip. The assembly has a clutch unit 7 driven by an electric motor 6 and coupled to the drive plate 1 by a poly-V belt 12. The clutch unit 7 rotates in one direction when powered by the electric motor 6, and when the clutch unit is rotated faster than the electric motor shaft the clutch unit disengages the drive to the motor. This arrangement permits use of the variable ratios available in the hub gear 3, e.g. higher the ratio of the hub gear the greater the torque output of the electric motor. The adaptor gear 4 is detachable from the drive plate 1, and carries a sprocket connected by a chain and further sprocket to rider-operable pedals. <IMAGE>

Description

SPECIFICATION The transmission drive assembly for an electrically assisted or powered vehicle This invention relates to a transmission drive assembly for an electrically assisted or powered vehicle.

Electrically assisted or powered vehicles are two, three or more wheeled forms of transport which utilise a form of electric motor assistance or power so as to reduce or eliminate the effort required to pedal or propel the vehicle. The vehicle may be ridden (in the case of an electrically assisted bicycle) as an ordinary bicycle, with the use of gears to reduce the physical effort required, which is either dictated by terrain or conditions. The electric motor is engaged by the rider either using manual or electrical switching as or when the need arises.

The electric motor is usually powered by some form of battery which is mounted onto the frame of the bicycle. As one use of this transmission drive assembly we have indicated at times, by example, the electrically assisted pedal cycle.

Under the provisions of the Electrically Assisted Pedal Cycle Act of August 1983 the speed of such a device cannot exceed 15 miles per hour (24 kilometres) in the case of two or three wheeled vehicles when being propelled or assisted by a motor.

There are usually two problems with electrically assisted or powered vehicles in the area of the electric motor. Firstly, the electric motor speed and power output is usually confined to a constant at a given RPM (revolutions per minute). The power output of an electric motor needed to overcome the inertia of vehicle and rider from a stationary or inclined position is limited, because it cannot utilise any form of variable power output relative to the power/RPM value of the motor. The second problem, is that any direct transmission drive from an electric motor to a wheel causes drag, as pedalling or propelling the vehicle without motor power the rider must pedal through the electric motor. This makes pedalling or coasting difficult.

According to the present invention there is provided two main components when assembled in tandem in their respective position, form the trans mission drive assembly. The first main component is the transmission drive plate which has two parts, the aluminium drive plate, and the adaptor gear which are bolted together. The second main component is the clutch drive which is fitted onto the output shaft of an electric motor. When the electric motor is activated the clutch drive trans mits the power through a poly-vee belt to the transmission drive plate.

The specific embodiment of the invention will need to be described by way of example by refer ence to the accompanying drawing in which: Figure 1 shows in perspective the transmission drive plate in position on a drive wheel attached to a hub gear.

Figure 2 illustrates the transmission drive plate and adaptor disassembled.

Figure 3 shows the assembly of the clutch drive onto an electric motor shaft.

Figure 4 shows the clutch drive frame from the electric motor shaft with apertures exposed for the fitting of bearings.

Figure 5 shows the transmission drive plate fitted onto a gear hub unit, housed in a drive wheel, and the clutch drive unit fitted to an electric motor.

These are connected by a poly-vee belt which transmits power from clutch units to transmission drive plates.

According to the present invention there is provided a transmission drive plate shown in Figure 1 fitted onto a hub gear unit 3 (of which no invention is claimed) which is connected to the driven wheel 2. The adaptor gear 4 is bolted to the transmission drive plate 1. The transmission drive plate 1 incorporating the adaptor gear 4 is held onto the gear hub unit by means of a circlip (not shown) which is usually provided with a standard hear hub. On the outer edge of adaptor 4 are teeth cut at 2" (12.7 milimetre). (The amount of teeth is variable relative to the ratio required between final drive and pedals. This is possible by changing the adaptor for more teeth or less). This forms the sprocket drive to the pedals of the vehicle (not shown). The polyvee grooves 13 are machined around the circumference of plate 1.The centre section of the adaptor 4 has cut into its internal diameter three drive teeth which engage on the outside diameter of hub gear 3 to permit drive into the gear box. The transmission drive plate 1 by virtue that it is attached to the gear unit 3 enables drive from the motor, in the form of a poly-vee belt around its outer circumference, to utilise the variable gear ratios given in that gear unit. This enables in certain hub gears the possibility of three ratios and power of electric cal motor operation. Thereto giving a variable speed at final drive when powered by an electric motor.

In Figure 2 the transmission drive plate 1 is shown disassembled from adaptor 4 with the locating hole for the adaptor plate 4 shown bored and drilled for the four adaptor bolts 5. On the inner diameter of the adaptor plate 4 can be seen the three drive teeth as mentioned in Figure 1. The holes shown in transmission drive plate 1 are there to lighten the weight of the transmission drive plate.

In Figure 3 the assembly of the clutch drive 7 is shown onto electric motor shaft 8 of electric motor 6. The clutch drive 7 has machined onto its outer circumference poly-vee grooves 13 to permit the use of a poly-vee belt. The positioning of clutch drive 7 is maintained by a bolt (shown in Figure 4) secured into motor shaft 8.

In Figure 4 the cross sectional view of the clutch drive 7 is shown with the relative positions and sizes of the sprag clutch 9 fitted to the rear of the clutch drive and support bearing 10 fitted t the front end of clutch drive. The fittings of this bear ing and sprag clutch are by means of press fit.

Clutch bolt 11 is fitted through support bearing 10 and is screwed into the electric motor shaft 8 (as shown in Figure 3). The arrangement of the sprag clutch 9 in the clutch drive 7 permits the drive of the motor to turn the clutch drive when the motor is activated. When movement from the rear wheel 2 through the transmission drive plate onto the clutch drive 7 exceeds the rotation of the electric motor, the clutch 9 releases its hold on motor shaft 8 so that there is no rotation of the electric motor 6 through its shaft connection.

In Figure 5 the drive layout arrangement is shown as it would be fitted as way of an example to an electric assisted bicycle. This shows how the drive through the poly-vee belt 12 is transmitted through clutch drive 7 to transmission drive plate 1 which is fitted over the gear hub unit on the driven wheel.

Components index 1. Transmission Drive Plate 2. Wheel 3. Hub Gear 4. Adaptor Gear 5. Adaptor Bolts 6. Electric Motor 7. Clutch Drive 8. Electric Motor Shaft 9. Sprag Clutch 10. Support Bearing 11. Clutch Bolt 12. Poly-Vee Belt 13. Poly-Vee Grooves

Claims

1. A transmission drive assembly comprising a drive plate with adaptor and clutch drive which when assembled on a hub gear unit and electric motor respectively on an electricaly assisted or powered vehicle enables the power output of the motor to be relative to the gear ratio selected.

2. A transmission drive assembly as claimed in Claim 1 which uses a multiple rib poly-vee belt to transmit the motor power through the clutch unit, into the drive plate which in turn acts through the gear box and rotates the driven wheel.

3. A transmission drive assembly as claimed in Claim 1 or Claim 2 wherein a sprag bearing is fitted into the clutch drive so as to transmit rotational movement of the electric motor through to the transmission assembly only, when the motor is engaged by means of external operation, but remains unable to transmit rotational movement or power in the opposite direction. Thus when the drive plate rotates the clutch unit, the sprag bearing is released from the motor shaft.

4. A transmission drive assembly as claimed in Claim 1 or Claim 2 which uses a detachable adaptor gear in various numbers of teeth, sizes and pitch which can be fitted to a two or more ratio gear hub using the three equally spaced internal teeth to locate and permit transmission of rotational power through to the gear hub.

5. A transmission drive assembly as claimed in any preceding claim wherein the size and diameter of the drive plate and clutch drive is variable relative to the reduction or increase value required to give specific revolution per minute at either the motor or driven wheel.

6. A transmission drive assembly that is claimed in any preceding claim that can be utilised to offer the variable ratio advantage of a hub gear to an electric motor when fitted to a front or rear wheel of an electrically assisted or powered vehicle.

7. A transmission drive assembly substantially as described herein with reference to Figures 1, 2, 3, 4 and 5 of the accompanying drawing.