GB2489450A

GB2489450A - Propulsion system for bicycles and similar vehicles

Info

Publication number: GB2489450A
Application number: GB201105172A
Authority: GB
Inventors: Graham David O'connell; Robert Michael Gideon Miller
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-03-28
Filing date: 2011-03-28
Publication date: 2012-10-03
Also published as: GB201105172D0; WO2012131292A1

Abstract

A highly flexible auxiliary propulsion system for a bicycle or similar personal-propulsion vehicle such as a wheelchair comprises a power unit 14 including a motor, removable power source and power control, mounting means 16 for simple attachment on the vehicle 18, a drive unit 20 comprising a driving wheel for applying a driving force to a wheel 22 or wheels, fixing means for mounting the drive unit and a flexible power-transfer shaft 28 connected to the power unit 14 and the drive unit 20 for providing rotational power to the driving wheel. The driving wheel preferably engages the rim of wheel 22.

Description

DESCRIPTION

PROPULSION SYSTEM FOR BICYCLES

AND SIMILAR PERSONALLY-PROPELLED VEHICLES

This invention relates to a propulsion system suitable for use on a bicycle and many similar vehicles, which are personally propelled, including wheel chairs. In one embodiment, the invention provides a universal propulsion system for cycles and personally-propelled vehicles in general.

Self-propelled vehicles, such as bicycles, are a popular form of transport for a number of reasons. They provide useful exercise for the user and are highly flexible, particularly in urban areas where vehicle congestion is an issue. They are cheaper and more environmentally friendly than is comparable forms of transport such as a motor car. They are relatively small and light, easily carried and portable. Families can take one or more bicycles by car on holiday, for the use of students at college, either in the back of a car or using readily available cycle carriers. Disadvantages of such vehicles include their limitation for longer distances and higher speeds, being dependant on the strength and stamina of the user, especially over difficult terrains such as steep hills. Less-abled people can also find personally-propelled personal vehicles prohibitively difficult to use.

One compromise solution is the provision of a purpose-built electric vehicle, such as an electric bicycle, designed to provide the advantages of personal and powered propulsion. There are several disadvantages of such vehicles however, including relatively high-cost, larger size and weight, more difficult to transport and higher risk of theft.

Another compromise solution is available in a variety of forms as a kit which can be attached to a standard bicycle. The existing art here has several weaknesses, including: 1. the need for technical ability to attach the system, which is beyond many potential users; 2. the need to interfere with the existing machinery and structure of the bicycle, such as its gears, wheels and frame -which can negate manufacturer warrantees; 3. the time and difficulty of attachment means that the systems are not designed to be easily and simply removed -hence a. risk of theft and vandalism is increased and b. re-use on multiple vehicles or removal to allow standard use of the bicycle is prohibitive.

It is therefore an object of the invention to improve upon the known art.

According to the present invention, there is provided a propulsion system for a bicycle or similar vehicle comprising a power unit which includes a motor, removable power source and power control, means for releasably io mounting the power unit on a frame of a vehicle, a drive unit comprising a driving wheel for applying a driving force to a wheel of a vehicle, fixing means for mounting the drive unit on a frame of a vehicle, and a flexible shaft connected to the power unit and the drive unit and for providing rotational power from the motor to the driving wheel.

is Owing to the invention, it is possible to provide a highly flexible system for driving a wheel or wheels of a bicycle or similar vehicle. Several propulsion solutions are enabled including single, dual and multiple-wheel drive. The propulsion system is portable and can be retro-fitted, by a non-specialist, to a large number of types and sizes of standard bicycles, tricycles, similar vehicles and for personally-propelled transport systems in general. With the system fitted, the vehicle has the benefit of being propelled by the propulsion system in addition to the vehicle's normal propulsion method. The system can likewise be quickly and easily removed from the vehicle for use on a different vehicle, to allow standard use of the vehicle, and to reduce risk of theft and vandalism.

Preferably, the drive unit drives the vehicle wheel rim via a wheel or wheels, finished in a suitable high-friction material. The power unit connects to the drive unit via a flexible shaft which attaches the power unit to the drive unit, transferring rotation power. The propulsion system allows a large variety of bicycle and similar vehicle types and sizes to be powered. Advantageously, the power-unit case houses a motor, power-source and controls and is mounted to the bicycle frame via simple clips. The power unit can be fitted and removed by the bicycle owner, making the system portable and guarding against theft. The system has minimal interference with the existing mechanics of the vehicle, and on a standard bicycle has no more affect than the existing brakes. The system can be easily removed from the vehicle leaving no trace of having been fitted. Any effect on vehicle warrantee is minimised.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-io Figure 1 is a side perspective view of a bicycle with a propulsion system fitted thereto and a partial side view of the bicycle, Figure 2 is a partial side view showing more detail of the bicycle and propulsion system of Figure 1, Figure 3 is a front perspective view of the bicycle with the propulsion is system fitted thereto, Figure 4 is a partial side perspective view of a power unit of the propulsion system, Figure 5 is a partial rear perspective view of the power unit of Figure 4, Figure 6 is a perspective view from above of a speed control of the propulsion system, Figure 7 is a perspective view from above of a drive unit of the propulsion system, and Figure 8 is a perspective view from below of the drive unit of Figure 7.

Figure 1 shows a propulsion system 10 that has been retro-fitted to a conventional bicycle 12. The propulsion system 10 can be fitted by a non-technical person, such as the ordinary owner of the bicycle 12. The purpose of the propulsion system 10 is to provide additional power to the user of the bicycle 12, as and when that user needs the additional propulsion. The propulsion system 10 converts a standard bicycle to an electric bike, without the need for the owner to purchase a new and expensive electric bike and without the user having to stop using their original bicycle 12. The propulsion system 10 can additionally be easily removed from the bicycle 12 should the owner wish store the propulsion system 10 safely or use it on a different bicycle.

More detail of the propulsion system 10 for the bicycle 12 is shown in Figure 2. The propulsion system 10 comprises a power unit 14, which comprising a motor, a power source for powering the motor which can be separately removed from the main-case, and control means for controlling the operation of the power source, easily attachable means 16 for mounting the power unit 14 on the frame 18 of the bicycle 12, a drive unit 20 comprising a driving wheel 22 for applying a driving force to a wheel 24 of the bicycle 12, fixing means 26 for mounting the drive unit 20 on the frame 18 of the bicycle 12, and a flexible shaft 28 connected to the power unit 14 and the drive unit 20 and for providing rotational power from the motor to the driving wheel 22.

The rotational power of the motor (or motors) is transferred over one or is more flexible shafts 28 to the drive unit 20 which drives the rim of the vehicle wheel or wheels 24. The flexible shafts 28 allow the power unit 14 and drive unit 20 to be mounted at different locations and orientations on the vehicle 12 and allow a large variety of vehicles types to be driven. A speed control (discussed in more detail below with reference to Figure 6) allows variable drive speeds. A counter-rotational dual-drive option and gearbox provides additional technical benefits.

Location and orientation flexibility also allows standard mass-produced motors and other transmission components to be utilised, reducing system costs. Where the motor is electrical, the power unit 14 can include both a battery and a battery charger to make portability and recharging more convenient. The power unit 14 can also include power-outlets for personal equipment and to allow power-generation and usage in isolated locations.

The power unit 14 connects, via the flexible shaft 28, to the rim-drive mechanism 20, driving the rim of a cycle wheel 24, in general the physical characteristics of the rims being very uniform across many vehicle types. The mechanism can be simply fitted and removed. Equal pressure is applied to opposite rims. The mechanism by design gives simple/low-cost high-gearing and de-clutching functions. The drive unit 20 can optionally provide re-generative braking and hence electric-power generation. The drive can be easily applied to multiple wheels.

The drive unit 20 can use a single wheel 22 on each rim or multiple wheels 22, and can also include a rim-cleaning function to promote both safer braking and more efficient drive. The mechanism 20 can use a latching manual engagement lever, thereby allowing simple drive-declutching when required and allowing different drive-to-rim pressures to be used according to climate and wheel characteristics. A lighter pressure can be used when in generation mode to reduce bearing friction. The motor and power source can be mounted in a single package, providing efficient space usage on the vehicle 12. An optional gearbox can also be included in the package. Alternative drive units can be accommodated with the system such as directly driving a wheel via a flexible shaft and gearing mechanism.

is Due to its features, both the power unit 14 and drive unit 20 can be fitted and removed by a non-specialist. This reduces fitting costs and gives portability, allowing convenient recharging away from the vehicle 12, allowing application to multiple vehicles and guarding against theft. The drive unit 20 features allow its application to a large variety of current and future personal-transport vehicles, where the drive can be applied in various ways, can be vehicle-mounted or worn by the user.

Figure 3 shows a front view of the bicycle 12 with the propulsion system in place. The power unit 14 comprises a housing 30 containing the motor, power source and control means and the mounting means 16 is for releasably mounting the housing 30 on the frame 18 of the bicycle 12. The clips 16 allow the user of the bicycle to easily attach and detach the housing from the frame 18 of the bicycle 12. The propulsion system also further comprises a speed control unit 32 for adjusting the speed and/or direction of the motor. The user while riding the bicycle 12 can adjust the speed of the motor and thereby adjust the amount of assistance that the propulsion system is providing, to suit the current needs of the user.

More detail of the power unit case 30 is shown in Figure 4. The power unit 14 is clipped to the frame 18 of the bicycle 12. The case 30 houses the motor, the power source, shaft-drive gearing and a clamp tensioner. A gear control 34 can be utilised by the rider of the bicycle 12 to change the output drive ratio, allowing the use of the propulsion system 10 on varying inclinations, and also allows application of the propulsion system 10 to various wheel sizes and also supports the de-coupling of the motor from the drive unit 20.

A drive-tensioner 36 is provided on the side of the housing 30 which is a rotary, geared and ratcheted control. The tensioner 36 applies, via a cable, variable pressure to drive-clamps (discussed in more detail below with reference to Figure 7). The tensioner 36 provides a torque-setting control for setting a desired pressure to the drive clamp. The tensioner 36 allows the propulsion system 10 to accommodate various wheel widths and wet weather-is conditions where higher pressure is required. A tension-release-key 38 is provided that releases the clamp-tension by de-clutching the drive. A cable 40 is also shown in this Figure, which connects the power unit 14 to the speed control 32 mounted on the handlebars of the bicycle 12.

Figure 5 shows the rear of the power unit 14 in more detail. Dual flexible drives 28a and 28b are shown, each of which connect to and rotate a drive wheel 22 of the drive unit 20. The motor output is geared to produce two counter-rotating outputs which connect to the flexible shafts 28. The counter-rotation is provided because the drive wheels 22 act on opposite sides of the wheel 24 of the bicycle 12. A clamp control cable 42 is also shown, which links the clamp tensioner 36 to the drive clamps.

The speed control 32 is shown in more detail in Figure 6. The speed control unit 32 is clipped to handlebars 44 of the bike 12. The speed control 32 is connected to the drive unit 14 via a cable 40, although this connection could be made via a wireless connection. The front of the speed control includes buttons 46 which provides stop 46a, go 46b, and variable speed control 46c.

The top of the speed control 32 is provided with a power-source charge indicator 48, which tells the user of the propulsion system 10 the current level of charge being stored by the power source within the power unit 14.

The preferred embodiment of the propulsion system 10 operates using a drive unit 20 that has driving wheels 22 on either side of the rim of a bicycle wheel 24. This is shown in more detail in Figures 7 and 8. To provide pressure to force the opposing driving wheels 22 together a drive clamp 50 is provided which is tensioned via a cable 42 tightened by the drive tensioner 36 on the power unit 14. The pressure is applied using the ratcheted clamp tensioner 36 and the connecting cable 42, which pull the drive units 20a and 20b equally against the wheel rim of the wheel 24.

The dual flexible shafts 28a and 28b connect to respective drive units 20a and 20b and are held in position relative to each other by a tie 56. By using dual counter-rotating flexible shafts 28 increased performance, lower stress on each shaft and the shaft tendency to twist is reduced. A Shaft strap is increases strength of flexible drive. The dual drive units 20 translate shaft torque to drive wheel torque. The dual units 20 reduce the pressure required to ensure there is sufficient friction between the drive wheels 22 and the wheel rim to drive it. Each shaft 28 drives a gear connected to the dual drive wheels 22 in each drive unit 20. Dual drive wheels 22 in each unit 20 allow a more compact unit, and are more stable than a single drive wheel under pressure.

The drive wheel material deforms under pressure, increasing the contact surface area and drive friction.

Figure 8 shows more detail of the drive clamp 50 and the drive units 20a and 20b. Each drive unit 20 is provided with a respective rim wiper 52.

The leading rim wiper 52 reduces the effects of wet and dust on the wheel rim.

As the wheel 24 rotates, the rim wiper 52 cleans the surface of the rim. The brakes of the bicycle 12 also have a beneficial cleaning effect. Each drive unit is also provided with a respective clamp clip 54. The easily attached clamp clips 54 securely attach each respective drive unit 20 to the vehicle 12. The clamp clips 54 and brace 55 resist side-to-side motion to allow the drives 20 to grip the wheel 24, plus back-forward motion to facilitate wheel drive.

Various system variations and additional features can be provided, some of which are discussed below. These can be integral parts of the system overall but can be optional for specific implementations. Various power unit variations are possible including using a single shaft which provides the simplest and lowest-cost option, or a dual-shaft which allows higher power to be delivered for a given shaft specification plus a counter-rotating dual shaft gives enhanced power-delivery, by coupling the two shafts, thereby reducing the tendency of drive components to twist. Multiple shafts can be used to allow multiple wheels to be driven. Drive-shaft variations in length, flexibility and io power-rating allow a variety of cost, power and vehicle types to be accommodated. Multiple drive-components which share the drive load also facilitate lighter and cheaper components to be used, such as plastics.

The system can be powered by any engine, but the preferred power unit 14 contains an electrical AC, DC or universal motor, drivable by existing and is future battery technology or fuel-cell technology or the like. Various drive unit variations are possible. The drive can be to a front wheel, a rear wheel or both wheels. Single drive wheel, single flexible shaft, opposed by an undriven idling wheel provides the lowest cost solution. Opposing counter-rotating drive units could be driven by a single shaft using gearing. Opposing counter-rotating drive units could be driven by dual shafts, as per the Figures above.

The drive units 20 can have one or more driving wheels 22.

The propulsion system 10 facilitates a variety of control and monitoring implementations including controls that can be wired or wireless and located within easy reach of brakes levers. The controls can be simple go-stop, fast- medium-stop, etc. or use variable speed, low-power high-distance or high-power. Regenerative braking can also be used, whereby the user braking to slow the bicycle 12 will recharge the power source of the power unit 14.The propulsion provided by the propulsion system 10 can linked to user-effort, such as requiring the user to pedal a cycle before the system will provide additional power. The controls can also provide simple power-usage and charge indication information.

The system can be easily removed to prevent its theft. Optionally, the system facilitates being locked in place and disabled, thereby making vehicle theft harder to accomplish. Standard application for the propulsion system 10 includes all types of cycles, delivery vehicles, passenger buggies, wheel-chairs, etc. Advanced applications include skate-boards, scooters, skates, large-wheel skates, etc. where the system can be worn by the user.

Claims

CLAIMS1. A propulsion system for a bicycle or similar vehicle comprising: o a power unit comprising a motor, a power source for powering the motor, and control means for controlling the operation of the power source, o mounting means for releasably mounting the power unit on a frame of a vehicle, o a drive unit comprising a driving wheel for applying a driving io force to a wheel of a vehicle, o fixing means for mounting the drive unit on a frame of a vehicle, and o a flexible shaft connected to the power unit and the drive unit and for providing rotational power from the motor to the driving wheel.
2. A system according to claim 1, wherein the power unit further comprises a housing containing the motor, power source and control means and wherein the mounting means is for releasably mounting the housing on the frame of a vehicle.
3. A system according to claim 1 or 2, wherein the driving wheel is for providing the driving force to the rim of a wheel of a vehicle.
4. A system according to claim 3, wherein the drive unit further comprises a second driving wheel for providing the driving force to the opposite rim of a wheel of a vehicle as the first driving wheel.
5. A system according to claim 3 or 4, and further comprising a drive clamp for providing a force to the or each driving wheel, the force for pressing the or each driving wheel into the rim of a wheel of a vehicle.
6. A system according to claim 5, and further comprising a drive tensioner comprising a rotary, geared and ratcheted control for applying pressure to the drive clamp.
7. A system according to claim 6, as appended to claim 2, wherein the drive tensioner is mounted on the exterior of the housing of the power unit.
8. A system according to claim 6 or 7, wherein the drive tensioner provides a torque-setting control for setting a desired pressure to the drive clamp.
9. A system according to any preceding claim, and further comprising a gear control for adjusting the drive ratio of the motor and/or for decoupling the motor from flexible shaft.
10. A system according to claim 9, as appended to claim 2, wherein the gear control is mounted on the exterior of the housing of the power unit.
11. A system according to any one of claims 5 to 10, as appended to claim 4, and further comprising a second flexible shaft connected to the power unit and the drive unit and for providing rotational power from the motor to the second driving wheel.
12. A system according to claim 11, wherein the second flexible shaft is rotated by the power unit in an opposite direction to the first flexible shaft.
13. A system according to any preceding claim, and further comprising a speed control unit for adjusting the speed and/or direction of the motor.
14. A system according to any preceding claim, wherein the drive unit further comprises a rim wiper for cleaning the rim of a wheel of a bicycle.