GB2478606A

GB2478606A - Drive unit for attachment to a manual operated wheelchair

Info

Publication number: GB2478606A
Application number: GB1005472A
Authority: GB
Inventors: Daniel Toby Stone
Original assignee: TGA ELECTRIC LEISURE Ltd
Current assignee: TGA ELECTRIC LEISURE Ltd
Priority date: 2010-03-05
Filing date: 2010-03-31
Publication date: 2011-09-14
Anticipated expiration: 2030-03-31
Also published as: GB2478606B; GB201003757D0; GB201005472D0

Abstract

A wheelchair drive unit 10 attachable to a wheelchair for assisting the propulsion thereof comprises: a gearbox 11 having opposed side faces 15 each provided with an axle 30 for carrying a ground-engaging wheel, a motor mounting means 35 by which an electric motor 12 may be coupled to the gearbox to drive the ground engaging wheels, and a battery support 13 for carrying a battery adapted to power the electric motor. The battery support may be made of plastics material and may be unitary molded. The battery support may also be releasably connected to the gearbox. The battery support may include a locating region 42 for housing an electrical unit interfacing the battery, the motor and a controller. The gearbox may house a worm drive.

Description

Wheelchair Drive Unit The present invention relates to a drive unit for a mobility vehicle and particularly to a drive unit that may be fitted to any wheelchair at (east to assist the propulsion thereof.

A range of mobility vehicles are available nowadays, including electrically powered scooters, electrically powered wheelchairs and also manual wheelchairs. Scooters are usually driven by the elderly or the disabled and comprise three or four wheels, an electric drive unit coupled to the rear wheels and a handle bar assembly by which the scooter can be steered and controlled.

Electrically powered wheelchairs usually have four wheels, an electrical drive unit drivingly coupled to the rear two wheels and a control panel for controlling the speed of the rear wheels and for steering the two front wheels. These vehicles can be very expensive and due to their size and weight they are not easily transported.

Conversely, manual wheelchairs are reasonably inexpensive and usually collapsible for convenient transportation. Such wheelchairs generally comprise a frame carrying a flexible seat and defining a pair of rearwardl.y extending handles by which the wheelchair may be pushed, two large rear wheels provided with handrails and mounted to the frame and also two small front wheels pivoted to the frame to enable the wheelchair to turn. This well known construction enables the wheelchair to be propelled by the user gripping the handrails or by an assistant holding the handles.

Electrical drive units are available which connect to manual wheelchairs and at least partially assist with the propulsion thereof. Typically they include at least one ground-engaging wheel coupled to an electrical drive unit and also a control unit for adjusting the speed. These known drive units have many shortcomings. For instance, the electrical units are exposed to the elements and consequently they are easily damaged. They are also made from several steel parts which are formed in the required shape, welded together and provided with a coating, thus making the assembly process expensive and time consuming.

Therefore, it is an object of the present invention to provide a drive unit that avoids those shortcomings.

According to the invention, there is provided a wheelchair drive unit attachable to a wheelchair to assist the propulsion thereof, the drive unit comprising: a gearbox having opposed side faces each provided with an axle for carrying a ground -engaging wheel; -motor mounting means by which an electric motor may be coupled to the gearbox to drive the ground engaging wheels; and -a battery support for carrying a battery adapted to power the electric motor.

The axle may comprise a single unit extending through the gearbox such that opposed end portions of the axle are provided on opposed faces or it may instead comprise two distinct parts such that each part is provided on a respective face.

n a preferred arrangement the motor includes connection means by which the wheelchair drive unit may be coupled to the wheelchair, though in alternative arrangements connection means may be provided on the gearbox, battery support or another feature of the wheelchair drive unit.

Preferably the battery support and the gearbox are two distinct components that are connected during assembly. This way, the gearbox and the battery support may be made from different materials using different manufacturing techniques as appropriate. n addition, a range of different size battery supports may be available for carrying different size batteries and any one of those battery supports may be fitted to a standard size gearbox.

Furthermore, if the gearbox or the battery support is damaged it is possible to replace only the damaged part and so avoid having to replace the entire drive unit. However, it is also feasible for the battery support to be integrally formed on the gearbox.

n a preferred arrangement the battery support may be slidably mounted to the gearbox. An arrangement of that nature may facilitate a secure connection that may be effected with minimal skill and in little time, thus reducing costs. For instance, one of the battery support and the gearbox may have at least one channel and the other of the battery support and the gearbox may have at least one abutment that locates within said at least one channel.

The cross-section of the or each channel and the or each abutment may be any shape provided they cooperate with one another. Preferably, the dimensions of the at least one channel and the at least one abutment are selected to form a reasonably snug fit therebetween to prevent inadvertent separation of those parts. For instance, the at least one abutment or the at least one channel may be tapered so that the force required to effect relative movement of those parts increases as they near full engagement. Additionally or alternatively, fastening means such as bolts or screws may be provided to secure the battery support to the gearbox.

n a preferred arrangement the gearbox may have an upper engagement surface and the battery support may have a lower engagement surface adapted to locate against the upper engagement surface of the gearbox. Those surfaces may take any form provided they are sized and shaped to co.operate and provide a stable connection. Preferably, the at least one channel and abutment may be defined on or adjacent those engagement surfaces.

An electric unit may be provided to interface the battery, the electric motor and a controller. Preferably, the battery support may define a locating region adapted to accommodate the electric unit and to shield it from the elements, particularly debris and water from roads and footpaths. Most preferably the locating region comprises a recess defined within the battery support and which mostly conceals the electric unit.

In one embodiment, the battery support includes a base and at least one wall upstanding at least partway along the periphery of the base to define the locating region. The locating region may have a shape corresponding to that of the electric unit, and is most likely to be rectangular. Furthermore, the at least one wall may extend around the rear and sides of the base so as to define an open front portion through which cables may pass in use for connecting the electrical unit to the battery and the controller.

Preferably a platform may be provided on the at least one wall to define a surface for supporting the battery in use. Furthermore the platform may extend outwardly from said at Least one wall and more preferably may extend beyond the rear and sides of the base. Advantageously, the surface may be at Least as Large as the portion of a battery to be Located thereon and most preferably includes a retaining Lip extending at Least partway therearound to enclose a Lower portion of the battery in use for added stability.

The drive unit may be furnished with a handle portion to facilitate easy handling when not coupled to a wheeLchair. Advantageously, that handle portion may comprise indentations, preferably a row of grooves and most preferably formed in a tower face of the platform extending rearward of the base. That way, the drive unit may be easily gripped, lifted and carried to the required Location. The grip portion may also be of great assistance when detaching the battery support from the gearbox.

Furthermore, the base may have a tower surface defining the Lower engagement surface of the battery support, such that the base connects directly to the gearbox.

Preferably, the drive unit is also furnished with a removable panel adapted to rest on the platform and conceal at least part of the locating region and most preferably the outline of the paneL corresponds with that of the platform. In one arrangement the panel is sized to abut the inside face of the retaining wall extending around the platform. Preferably the panel may be secured to the platform by fastening means such as screws or bolts.

Alternatively or additionaUy, detents may be provided on the panel or the platform and which are arranged so that the panel may be snap-fitted onto the platform so that the relative positions of those parts are maintained.

Furthermore, the panel may include a lower face to which the electrical unit may be secured such that said electrical unit locates within the recess when the panel is suitably positioned on the platform. The electrical unit may be secured to the panel by suitable fasteners or may even be carried in a cradle provided on the lower face of the panel.

Advantageously openings are provided in the at least one wall and which serve to vent the locating region thereby enabling cool air to circulate around the electrical unit. Those openings may take any shape, but are most preferably narrow slots extending upwardly and spaced (ateraUy apart around portions of the at (east one wall.

Preferably the drive unit includes at least one shield arranged at least partialLy to overlie the ground engaging-wheeLs. Predominantly the or each shield may be adapted to minimise surface water being flicked upwardly as the ground engaging wheels rotate but the or each shield may also minimise the Likelihood of debris and other items becoming entrained between the wheels and the gearbox. Preferably the at least one shield is integral to the battery support and most preferably comprises a pair of curved members depending from the lower face of the platform and spaced apart on opposed sides of the locating region. In one arrangement the at least one shield includes an abutment that engages a shoulder formed on the gearbox.

Preferably the battery support member is made from a rigid plastics material and is most preferably moulded as a single unit.

By way of example only, one embodiment of the present invention will now be described in detail, with reference being made to the accompanying drawings, in which: Figure 1 is a front perspective view of a drive unit according to the invention, but without wheels; Figure 2 is a rear perspective view of the drive unit shown in Figure 1; Figure 3 is a side view of the drive unit shown in Figures 1 and 2; Figure 4 is a plan view of the drive unit shown in Figures 1 to 3; Figure 5 is a bottom view of the drive unit shown in Figures 1 to 4, but with he motor removed; Figure 6 is a front view of the drive unit shown in Figures 1 to 5, but with motor removed; Figure 7 is a rear view of the drive unit shown in Figures 1 to 6; Figure 8 is a front perspective view of the drive arrangement shown in Figures 1 to 7, but with the panel detached from the platform; Figure 9 is a plan view of the drive arrangement shown in Figure 8; Figure 10 is a front perspective view of a gearbox forming part of the invention; Figure 11 is a front perspective view of a battery support forming part of the invention; and Figure 12 is a bottom perspective view of the battery support of Figure *11.

Referring to Figures I to 8, there is shown a drive unit 10 to be attached to a conventional wheelchair (not shown). The drive unit 10 incLudes a gearbox 11, a motor 12 attached to the front of the gearbox and a battery support 13 mounted above the gearbox. With particular reference to Figure 10, the gearbox 11 has opposed side faces 15, a front face 16, a top face 17, and a curved face extending around the rear 18 and the base 19 of the gearbox. The rear face 18 curves inwardly to define a hollow 20 in which a portion 21 of the battery support 13 locates, and which shall be discussed in more detail below. A bed 25 is provided on the top of the gear box 11 and which defines the top face 17, the bed being slightly wider than the gearbox 11 such that its edges project beyond the side faces 15 to define flanges 26.

A wheel axle 30 extends through openings (not shown) in the side faces 15 of the gearbox 11 and is rotatabty supported on bearings (not shown) disposed within cups 31 formed in the side faces. The gearbox 11 houses a conventional worm drive (not shown) comprising a worm gear fixedly carried on the wheel axle 30 and a worm carried on a second axle extending transverseLy to the wheel axle and arranged in meshing relationship with the worm gear.

The front face 16 is furnished with a motor mounting portion 35 having a circular front face to which a rear end of the motor 12 attaches and through which the shaft of the motor is coupled to the second axle. The front end 36 of the motor 12 is adapted to receive a wheelchair mounting bracket (not shown) comprising a tubular member having its axis arranged parallel to that of the wheel axle 30 and through which, in use, a rod extending across the width of the wheelchair locates. Thus, this arrangement enables relative pivoting movement between the mounting bracket and the rod and therefore between the drive unit and the wheelchair. The rod should be positioned so that the drive unit 10 locates beneath the seat of the wheelchair and the wheel axle 30 extends below the axis of the rear wheels of the wheelchair.

The battery support 13 is made from a rigid plastics material and moulded as a single piece. The battery support 13 includes a rectangular base 40 and a wall 41 extending partway around the base so as to define a cavity 42 that houses an electric unit (not shown) interfacing the battery (not shown), the motor 12 and the controller (not shown). The wall 41 does not extend entirety around the front of the base so as to define an opening 43 through which electrical cables may pass. Ribs 44 extending along the base 40 include upstanding flanges 45 for positioning the electric unit. Elongate openings 46 are formed in the front and rear portions of the wall 41 which serve as vents to facilitate effective air flow in and out of the cavity 42.

The battery support 13 also includes a platform 50 extending outwardly from the walls 41 and which defines a generally U-shape support surface 51 extending around the sides and the rear of the walt 41. The innermost side portions of the platform 50 connect to a tower portion of the sidewalls 41 and curve upwardly such that the outermost portion defines the limbs of the U-shaped support surface. To increase the rigidity of the battery support 13, ribs 52 interconnect the innermost portion of the platform and the upper portion of the sidewaUs 41. On the underside of the platform behind the cavity 42 there is formed four shaLlow depressions on which four fingers of a person manoeuvring the drive unit may grip. Those depressions greatly assist the manual handling of the drive unit.

A skirt 55 is provided at the rear of the battery support 13 and which includes two shield portions 56 curving downwardly from the underside of the platform 50, one each side of the cavity 42. tn use, each shield portion 56 overlies a respective wheel (not shown) mounted on the wheel axle 30 so as to deflect debris that would inevitably be flicked upwardly as the wheels rotate.

Those shield portions 56 also resist larger items of debris entangling between the wheels and the gearbox 11. The shield portions converge below the rear wall to define an abutment 21 that locates in the hollow 20 defined on the rear face 18 of the gearbox 11.

The base 40 has a tower face that stidabty engages the top face 17 defined by the bed 25 of the gearbox ii. In particular, two elongate members 62 depend from the tower face of the base 40, each having an L-shape cross-section defining a channel 63 for receiving a respective flange of the bed 25. To assemble the drive unit 10, the battery support 13 is presented to the rear of the gearbox 11 with the channels 63 aligned with the flanges 26 and then urged forward relative to the gearbox 11 so that the flanges progress along the channels. The space between the flanges and the space between the channels are both tapered in the same direction so as to cause a degree of resistance as the flanges progress further along the channels. Once the flanges and the channels are fully engaged, disengagement of those parts is possible only when they are urged in opposite directions with sufficient force. As such, inadvertent disengagement is prevented.

A panel 60 having an outline corresponding to that of the platform 50 may be mounted to the upper surface 51 to conceal the cavity 42 and the electrical unit located therein.

Claims

CLAIMS1. A wheelchair drive unit attachable to a wheelchair to assist the propulsion thereof, the drive unit comprising: a gearbox having opposed side faces each provided with an axle for carrying a ground-engaging wheel; * motor mounting means by which an electric motor may be coupLed to the gearbox to drive the ground engaging wheels; and -a battery support for carrying a battery adapted to power the electric motor.
2. A drive unit as claimed in claim 1, wherein the battery support is releasably mounted to the gearbox.
3. A drive unit as claimed in any preceding claim, wherein the battery support is slidabty mounted to the gearbox.
4. A drive unit as claimed in claim 3, wherein one of the battery support and the gearbox has at least one channel and the other of the battery support and the gearbox has at least one member that Locates within said at least one channel.
5. A drive unit as claimed in any preceding claim, wherein the gearbox has an upper engagement surface and the battery support has a lower engagement surface adapted to Locate against the upper engagement surface of the gearbox.
6. A drive unit as claimed in any preceding claim, wherein the battery support includes a locating region in to which an electrical unit that interfaces the battery, the motor and a controller may be located in use.
7 A drive unit as claimed in claim 6, wherein the locating region comprises a recess defined in the battery support.
8. A drive unit as claimed in claim 6 or claim 7, wherein the battery support includes a base, at least one wall upstanding from the periphery of the base to define the locating region and a platform extending outwardly from the at least one wall so as to define a surface for supporting the battery.
9. A drive unit as claimed in claim 8, wherein the base is generaLly rectangular and has opposed sidewalls and a rear watt, and the platform extends outwardly therefrom to define a generally rectangular support surface on which the battery locates.
10. A drive unit as claimed in claim 8 or claim 9, wherein the base has a lower face defining the tower engagement surface of the battery support.
11. A drive unit as claimed in any of claims 8 to 10, and further comprising a panel adapted to rest on the platform and conceal at least part of the locating region.
12. A drive unit as claimed in claim 11, wherein the panel includes opposed upper and lower faces and fastening means by which the electricaL unit may be attached to the Lower face and located in the locating region.
13. A drive unit as cLaimed in any of claims 8 to 12, wherein one or more opening is provided in the at least one wall to vent the electrical unit disposed in the locating region.
14. A drive unit as claimed in any preceding claim and further comprising at least one shield arranged at least partially to overlie the ground engaging.wheels.
15. A drive unit as claimed in any preceding claim, wherein the battery support member is made of plastics.
16. A drive unit as ctaimed in any preceding cLaim, wher&n the battery support member comprises a unitary mouLding.
17. A drive unit as cLaimed in cLaim I and substantiaLLy as hereinbefore described with reference to the accompanying drawings.