GB2559626A

GB2559626A - Drive apparatus

Info

Publication number: GB2559626A
Application number: GB1702400.1A
Authority: GB
Inventors: Joseph Palmer Hugo
Original assignee: Revolutionworks Ltd
Current assignee: Revolutionworks Ltd
Priority date: 2017-02-14
Filing date: 2017-02-14
Publication date: 2018-08-15
Also published as: GB201702400D0

Abstract

A drive apparatus 100 particularly for use with a bicycle, comprising a mount 13,14 for fixing the apparatus to a bicycle, a swing arm 15 pivotally attached to the mount 13,14, a drive roller 4 attached to the swing arm 15 for driving a wheel of the bicycle, a motor 17 for providing power, and a planetary gear train (3, 7, 16) for transmitting power from the motor 17 to the drive roller 4. The swing arm 15 may pivot between a first non-drive position and, when power is applied, a second drive position where the apparatus engages and may drive the wheel of the vehicle. Such movement may be due to inertial effects on starting the drive 100. Also disclosed are methods of providing auxiliary power to a vehicle and a bicycle comprising the drive apparatus. Other vehicles contemplated include scooters, wheelbarrows, carts, long boards, trolleys and so-called hover boards.

Description

(71) Applicant(s):

REVOLUTIONWORKS LTD

Chesterfield Buildings, Westbourne Place, Bristol, BS8 1RU, United Kingdom (72) Inventor(s):

Hugo Joseph Palmer (56) Documents Cited:

GB 2450863 A US 4386675 A US 20150336632 A1

JP 2000095177A1 US 3826324 A US 20130225360 A1 (58) Field of Search:

INT CL A63C, B62B, B62D, B62K, B62M Other: EPODOC, WPI (74) Agent and/or Address for Service:

Atherton Knowles

St Brandon's House, 29 Great George Street, Bristol, BS1 5QT, United Kingdom (54) Title of the Invention: Drive apparatus

Abstract Title: Tyre engaging drive apparatus (57) A drive apparatus 100 particularly for use with a bicycle, comprising a mount 13,14 for fixing the apparatus to a bicycle, a swing arm 15 pivotally attached to the mount 13,14, a drive roller 4 attached to the swing arm 15 for driving a wheel of the bicycle, a motor 17 for providing power, and a planetary gear train (3, 7, 16) for transmitting power from the motor 17 to the drive roller 4. The swing arm 15 may pivot between a first non-drive position and, when power is applied, a second drive position where the apparatus engages and may drive the wheel of the vehicle. Such movement may be due to inertial effects on starting the drive 100. Also disclosed are methods of providing auxiliary power to a vehicle and a bicycle comprising the drive apparatus. Other vehicles contemplated include scooters, wheelbarrows, carts, long boards, trolleys and so-called hover boards.

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Drive Apparatus

The present invention relates to drive apparatus for use with wheeled vehicles, especially bicycles. The invention also relates to methods for providing auxiliary power to vehicles and to bicycles and other vehicles having such drive apparatus mounted thereon.

It is known to provide power to vehicles using, for example, direct drive hub motors, geared hub motors, and mid-drive setups that convey the power through a chain, belt or shaft. Unfortunately, such methods tend to be heavy, inefficient, complicated, wasteful on materials, and expensive. Weight, complexity and inefficiency are a particular problem for human powered vehicles such as carts, trolleys, scooters and especially bicycles. With powered bicycles it is often the case that the power system is integral to the vehicle which may be costly and potentially impractical for existing owners of conventional bicycles.

It is useful for systems intended for human powered vehicles if the power may be both engaged and disengaged. There have been attempts to provide such systems.

US-A-5,799,747 discloses a compact, lightweight power assist system for a human powered vehicle that has an integral automatic clutch for engaging and disengaging power assist at appropriate times during the operation of the vehicle.

WO-A-2016/128369 discloses an electric assist device for a bicycle that may be 20 engaged and disengaged by an electric device that includes a position sensor.

However, a problem with known drives including assistance drives is complexity, lack of robustness and susceptibility to wear and tear especially as a result of dirt and moisture in the environment getting into the mechanism.

There is, therefore, a need for a compact drive that may be engaged or disengaged 25 from the vehicle so that power assistance may be provided when necessary but drag is not a problem when the assistance is no longer needed. Such a drive should be simple and robust and less susceptible to dirt-induced wear and tear.

It is an aim of the present invention to address this need.

The present invention accordingly provides, in a first aspect, a drive apparatus for use with a wheeled vehicle, the drive apparatus comprising a mount for fixing the apparatus to the vehicle, a swing arm pivotally attached to the mount by a pivotal attachment, a drive roller for driving a wheel of the vehicle, the drive roller being attached to the swing arm, a motor for providing power, and a planetary gear train for transmitting power from the motor to the drive roller.

Preferably, when mounted and in use, the swing arm is able to pivot between a first non-drive position and a second drive position where the apparatus engages, and may drive, the wheel of the vehicle.

More preferably, when mounted and in use, power transmitted to the drive roller may result in a moment about the pivotal attachment causing the swing arm to pivot to the second, drive position. The arrangement is such that the swing arm may have a pivot attachment (e.g. on a shaft and bearings that are fixed inside the mount) off-centre to the drive roller. Engagement may be enabled by the change of rotation inertia of the driven system that may produce an upward moment about the pivotal attachment of the swing arm.

This is advantageous because the rotational inertia and consequent moment of the drive apparatus itself causes engagement to the wheel which is a simple and robust way of power being applied when necessary. Once in contact the power transferred would tend to continue to hold the drive roller in engagement with the wheel.

Preferably, the mount is adapted so that, when mounted and in use, and when no power is supplied, the swing arm is able to pivot to the first non-drive position. This may be achieved by the apparatus comprising a biasing mechanism to bias the swing arm to pivot to the first non-drive position when power is not supplied. The biasing mechanism may be a spring or may be a servo. However, preferably, pivoting to the first non-drive position is under the influence of gravity.

Thus, advantageously, when no power is applied, there is substantially no force engaging the drive roller on the wheel and so the swing arm may pivot thereby disengaging the drive roller from the wheel. This is greatly advantageous because the apparatus allows e.g. when mounted on a bicycle, a power assisted bicycle that provides the same efficiency as it would even without the apparatus mounted because no additional induced or mechanical drag is caused by the drive apparatus powertrain when power is no longer applied.

The apparatus may further comprise a casing for holding the planetary gear train and/or the motor. Preferably, the casing is attached to the swing arm.

Thus, advantageously, the components of the powertrain (gear train, motor and drive roller) may be attached to the swing arm, providing a compact apparatus that may use a small motor, in particular a small electric motor, to provide power. Although, small electric motors may produce low torque they do provide relatively high rotational speed.

If the motor is an electric motor it may be a DC motor, either brushed or brushless. The motor may be such that it is a sensored or sensorless motor. Input may be trapezoidal, sinusoidal or field orientated control.

The planetary gear train provides efficient power output from the small motor to the drive roller.

The planetary gear train preferably comprises a sun gear, at least one planet gear, preferably at least two planet gears, and a ring gear. Preferably, the apparatus is adapted so that the motor drives the sun gear. Usually, the motor will comprise a motor shaft which is connected to and which drives the sun gear. The planetary gear train may comprise at least one carrier.

The planetary gear train may comprise a friction planetary gear train, but preferably comprises toothed gears. The toothed gears may be spur or helical. It is preferred that the sun gear has 20 teeth or fewer, preferably 18 or fewer and more preferably 16 or fewer. Generally, a lower number of teeth in the sun gear provides improved gear ratio and torque.

The gear ratio in the planetary gear train may be about 4:1 to 5:1 By adjustment of the numbers of teeth in the sun, planet and ring gears the gear ratio may be in the range 4:1 to 12:1.

The apparatus may be adapted so that the ring gear drives the drive roller or a planet gear drives the drive roller. Preferably, the ring gear is connected to and drives the drive roller.

Preferably, the drive roller rotates about a drive axis, the pivotal attachment 5 rotates about a swing axis and the drive axis and the swing axis are not co-axial.

Preferably, the axes of rotation of the motor, the planetary gear trains and the drive roller are substantially co-axial.

The pivotal attachment may comprise a swing shaft.

Preferably, the pivotal attachment comprises a swing adjuster to adjust the 10 position of the swing arm when in the second drive position and thereby adjust the force of engagement to the wheel when mounted and in use.

Preferably, the apparatus is adapted so when mounted and in use, the apparatus engages the rim of the wheel, preferably engages the tyre of the wheel. This is advantageous because the circumferential speed of the tyre is relatively high compared with that of the wheel hub or crank drives and therefore may provide that the final drive speed is nearer to the motor’s optimal speed.

The drive roller may contact the wheel directly, but preferably the drive roller comprises a contact sleeve for engaging a wheel of the vehicle. This is advantageous because it enables the contact sleeve to be optionally replaced (for example if worn) and enables the use of e.g. a contact sleeve with a high friction surface to provide good power transfer to the wheel in all weather conditions.

The contact sleeve may comprise an elastomer, for example a thermoset or thermoplastic elastomer. A preferred material for the contact sleeve is polyurethane, for example thermoset polyurethane, preferably elastomeric polyurethane.

The shore hardness (A) of the contact sleeve material may be in the range 40 to

95, preferably 50 to 90, more preferably 60 to 90, even more preferably 70 to 90, most preferably 75 to 85.

The contact sleeve may comprise engaging ridges, bumps and/or teeth to further improve power transfer, although this may increase noise and tyre wear.

The drive apparatus may be usefully adapted to be used with a vehicle, preferably a human powered vehicle such as a cycle, a scooter, a self-balancing personal vehicle, a hoverboard, a wheelbarrow, a cart, or a trolley.

The drive apparatus may be an auxiliary assistance drive or may be substantially the only drive.

Preferably, the apparatus is adapted to be used with a bicycle. The mount may be adapted so that the apparatus is mountable to a seat tube or seat stay or seat post or rack (or other parts of the cycle) which is convenient and discreet.

The drive apparatus of the invention is therefore useful in providing auxiliary powered assistance to a vehicle.

Thus, in a second aspect, the present invention provides, a method for providing auxiliary power to a vehicle, preferably a bicycle, the method comprising, a) providing a drive apparatus as in the first aspect mounted on the vehicle so that, when powered, the apparatus engages a wheel of the vehicle, b) applying power to the drive apparatus thereby transmitting power to the wheel of the vehicle.

In a third aspect, the present invention provides a vehicle having mounted thereon a drive apparatus according to the first aspect.

In a fourth aspect, the present invention provides a bicycle comprising a drive apparatus as in the first aspect, the drive apparatus being mounted on a seat stay or seat tube or seat post of the bicycle and positioned when powered so as to engage a wheel of the bicycle.

This is advantageous as a discreet setup as well as being compact and is generally compatible with most bicycle frames.

An embodiment of the present invention will now be described with reference to the following figures, in which:

FIG. 1 is an exploded view of drive apparatus according to the invention.

FIG. 2 shows front (A), side (B), plan (C), and isometric (D) views of the drive apparatus of FIG 1.

FIG. 3 shows front (Al) back (BI), front perspective (A2) and back perspective (B2) views of the drive apparatus of Figs 1 and 2 mounted on a bicycle in the region between the seat tube, seat stay tubes and the wheel.

The drive apparatus 100 is shown in FIG 1 and 2. The drive apparatus 100, in use, transmits power from the electric motor 17 to the drive roller 4 which comprises a contact sleeve 1 which has a high friction surface and engages and thereby transmits power to the bicycle tyre (see FIG 3). The torque from the motor 17 is stepped-up (rpm reduced and torque increased) through a series of planetary gears, including planet gears 7, ring gear 3 and sun gear 16. The sun gear 16 is fixed to the motor output shaft 27 of the motor 17 and transmits torque to the planet gears 7. The torque is transmitted from the planet gears 7 to the ring gear 3. The ring gear 7 is coupled to the drive roller 4 and the drive roller 4 comprises the contact sleeve 1, so that the motor 17 can provide power to the bicycle at an efficient RPM.

The motor 17 and planetary gears (16, 7, 3) are held in place by a casing 10. The main ball bearing 11 is seated on the casing 10 and so also holds the drive roller 4 in position.

The planet gears are held in place and rotate upon planet ball bearings 6 (the planet ball bearing outer races are visible in FIG 1) that are fixed to the motor and gearbox case 10 by bolts 5 and spaced offset with washers 8. The motor 17 is fixed in place to the casing 10 with case bolts 9.

The gears 3,7, and 16 and planet bearings 6 are protected from foreign contaminates such as water and dirt by the end-cap 2 that is pressed into position inside the drive roller 4. The main ball bearing 11 (the main ball bearing outer race is visible in FIG 1) also provides sealing. The motor 17 is sealed with the motor-cap 18 which may also act as a heatsink.

The powertrain of motor 17, planetary gears, casing 10 and drive roller 4 are located in a swing arm powertrain seat 28 in the form of an aperture in the swing arm 15. The powertrain is held in place in the swing arm 15 by the motor-cap 18.

The gear ratio is approximately 4.33:1, and by adjustment of the number of teeth 5 in the sun, planet and ring gears may be changed to 6.5:1 or higher (e.g. to 12:1).

The swing arm 15 is arranged so that it may pivot using a pivotal attachment to the mount 13,14. Specifically, the swing arm 15 may pivot about a swing shaft 25 seated in a swing shaft seat/aperture 26 upon bearings (not visible) fixed to the rear mount 14. The rear mount 14 and front mount 13 are bolted together using bolts 12 to clamp to the bicycle seat tube (not shown in FIG 1, see FIG 3).

FIG 3 shows the drive apparatus 100 mounted on a bicycle and positioned in the triangular region between the seat tube 104, seat stays 106, 107, and wheel 102. The drive apparatus 100 in FIG 3 is shown in the rest (i.e. no power) position. When there is no power the motor is not engaged with the wheel and hangs by gravity attached to the swing arm 15 suspended from the pivotal attachment of the front mount 14.

Once power is supplied to the motor 17 the torque generates a change in rotational inertia resulting in a moment at the swing arm 15 causing the powertrain to rotate and then contact sleeve 1 of the drive roller 4 to engage the tyre 103 of the bicycle wheel 102. Thus, the action of the swing arm 15 pivoting into the tyre 103 produces contact between the contact sleeve 1 and the tyre 103. The torque from the contact sleeve 1 in turn produces more contact pressure as it rolls on and up the tyre 103 until equilibrium is reached.

The point of equilibrium depends on the tyre width, tyre pressure, power demand, and mounting position of the system. The swing arm position may be adjusted by swing arm adjusters. In the embodiment illustrated in FIGS 1 to 3, the swing arm adjuster comprises two grub screws (not shown in the FIGS) in the rear mount 14. The swing arm adjusters may be moved to limit the rotation of the swing shaft and thereby adjust the maximum engagement position of the drive apparatus to ensure that the roller does not dig too far into the tyre wasting power and the minimum engagement position to reduce the chances of the drive roller 4 contacting the frame of the bicycle.

Reference Numerals

5	1	Contact sleeve
	2	End cap
	3	Ring gear
	4	Drive Roller
	5	Planet Gear bolts
10	6	Planet gear ball bearing
	7	Planet Gears
	8	Sealing Washers
	9	Case bolts
	10	Case
15	11	Main ball bearing
	12	Fixing bolts
	13	Front mount
	14	Rear mount
	15	Swing arm
20	16	Sun gear
	17	Electric motor
	18	Motor cap
	25	Swing shaft

Swing shaft seat/aperture

Motor output shaft

Swing arm powertrain seat

100 Drive apparatus

102 Bicycle wheel

103 Bicycle tyre

104 Bicycle seat tube

106 First bicycle seat stay

107 Second bicycle seat stay

Claims

1. A drive apparatus for use with a wheeled vehicle, the drive apparatus comprising a mount for fixing the apparatus to the vehicle,

5 a swing arm pivotally attached to the mount by a pivotal attachment, a drive roller for driving a wheel of the vehicle, the drive roller being attached to the swing arm, a motor for providing power, and a planetary gear train for transmitting power from the motor to the drive roller.

2. A drive apparatus according to claim 1, wherein, when mounted and in use, the swing arm is able to pivot between a first non-drive position and a second drive position where the apparatus engages and may drive the wheel of the vehicle.

15

3. A drive apparatus according to claim 2, wherein, when mounted and in use, power transmitted to the drive roller results in a moment about the pivotal attachment causing the swing arm to pivot to the second, drive position.

4. A drive apparatus according to either claim 2 or claim 3, wherein the mount is

20 adapted so that, when mounted and in use, and no power is supplied, the swing arm is able to pivot to the first non-drive position under the influence of gravity.

5. A drive apparatus according to any one of the preceding claims, further comprising a casing for holding the planetary gear train and/or the motor.

6.

A drive apparatus according to claim 5, wherein the casing is attached to the swing arm.

7. A drive apparatus according to any one of the preceding claims, wherein the

5 planetary gear train comprises a sun gear, at least one planet gear, and a ring gear.

8. A drive apparatus according to claim 7, wherein the apparatus is adapted so that the motor drives the sun gear.

10

9. A drive apparatus according to either claim 7 or claim 8, wherein the apparatus is adapted so that the ring gear drives the drive roller or a planet gear drives the drive roller.

10. A drive apparatus according to any one of the preceding claims, wherein the pivotal attachment comprises a swing shaft.

11. A drive apparatus according to any one of the preceding claims, wherein the drive roller rotates about a drive axis, the pivotal attachment rotates about a swing axis and the drive axis and the swing axis are not co-axial.

20

12. A drive apparatus according to any one of the preceding claims, wherein the axes of rotation of the motor, the planetary gear train and the drive roller are substantially coaxial.

13. A drive apparatus according to any one of the preceding claims, wherein the

25 pivotal attachment comprises a swing adjuster to adjust the position of the swing arm when in the second drive position and thereby adjust the force of engagement to the wheel when mounted and in use.

14. A drive apparatus according to any one of the preceding claims, wherein the

5 apparatus is adapted so when mounted and in use, the apparatus engages the rim of the wheel, preferably engages the tyre of the wheel.

15. A drive apparatus according to any one of the preceding claims, wherein the drive roller comprises a contact sleeve for engaging a wheel of the vehicle.

16. A drive apparatus according to claim 15, wherein the contact sleeve has a Shore Hardness (A) in the range 50 to 90.

17. A drive apparatus according to any one of the preceding claims, wherein the 15 motor is an electric motor.

18. A drive apparatus according to any one of the preceding claims, wherein the apparatus is adapted to be used with a vehicle human powered vehicle, preferably selected from a cycle, a scooter, a wheelbarrow, a cart, a long board, a hoverboard, or a

20 trolley.

19. A drive apparatus according to any one of the preceding claims, wherein the apparatus is adapted to be used with a bicycle and wherein the mount is adapted so that the apparatus is mountable to a seat tube or seat stay.

20. A method for providing auxiliary power to a vehicle, preferably a bicycle, the method comprising,

a) providing a drive apparatus as claimed in any one of claims 1 to 18 mounted on the vehicle so that, when powered, the apparatus engages a wheel of the vehicle,

5 b) applying power to the drive apparatus thereby transmitting power to the wheel of the vehicle.

21. A vehicle having mounted thereon a drive apparatus as claimed in any one of the preceding claims 1 to 19.

22. A bicycle comprising a drive apparatus as claimed in any one of the preceding claims 1 to 19, the drive apparatus being mounted on a seat stay or seat tube of the bicycle and positioned so as to engage a wheel of the bicycle, when powered.

Intellectual

Property

Office

Application No: GB 1702400.1 Examiner: Mr Philip Osman