GB2322835A

GB2322835A - Geared hub for a hand-propelled wheelchair

Info

Publication number: GB2322835A
Application number: GB9704253A
Authority: GB
Inventors: Michael Lovegrove
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-02-28
Filing date: 1997-02-28
Publication date: 1998-09-09
Anticipated expiration: 2017-02-28
Also published as: GB9704253D0; GB2322835B; WO1998037849A1

Abstract

A geared hub 10 is provided in the centre of an otherwise conventional wheelchair wheel 31, said hub having a single fixed gear ratio, preferably a reduction ratio. The hub may be provided with a handrail 33 separate from a handrail 32 that turns the wheel directly. The hub may allow the wheel to be turned backwards and forwards. Each wheel of a wheel chair may be fitted with such a hub. The geared hub may feature planetary gears.

Description

REDUCTION GEARING FOR HAND PROPELLED WHEEL CHAIRS FIELD OF INVENTION THIS PRESENT INVENTION RELATES TO REDUCTION GEARING WHICH CAN BE FITTED TO HAND PROPELLED WHEELCHAIRS TO ENABLE THE PERSON WHO IS IN THE WHEELCHAIR TO TRAVEL UP INCLINES UNAIDED BY ANOTHER PERSON.

Background to the present invention.

Persons who are unfortunate enough to have to use a wheelchair to transport themselves, often find difficulty in propelling themselves up an incline. quite often it is necessary for another person who is quite ambulant to push the wheelchair along.

Although electrically driven battery powered wheelchairs are in use they are expensive and require careful maintenance and inspection. There are many millions of hand propelled wheelchairs in use which are entirely dependant on the ability of the chairborne person to cause it to move along roadways and up inclines.

It is an object of the present invention to provide a gearing arrangement for the hand propelled type of wheelchair, according to which the difficulties referred to above may be reduced or overcome.

According to the invention, a hand propelled wheelchair comprising a frame carrying a seat and supported by road wheels each having an annular handwheel attached near the periphery thereof for exerting a direct manual driving force to the wheel, in which the hub of each road wheel carries a secondary hand-grip drivingly connected to the hub through a gear train within the hub, whereby the secondary handwheel is operable to drive the road wheel at a different rotational speed from that of the secondary handwheel.

Although the gear train may provide a higher gearing ratio with respect to the direct-drive or primary hand-grip, for use for recreational or competitive purposes, the invention is particularly intended for general purposes wherein the gear train will provide a lower gearing ratio.

The embodiment of this present invention comprises of a spindle on which are mounted bearings which extend almost the total length of the hub the bearings are oilite or roller, the spindle is fixed to the wheelchair frame in the normal manner and will not rotate. A drum shaped hub runs over the spindle supported by the bearings and is free to rotate forwards or backwards. The drum shaped hub has flanges at both sides and is closed at one end and open at the other,the flanges have evenly spaced holes around the circumference and when placed in the centre of a wheel chair rim can be radially spoked to become an integral part of the wheel.

In the centre of the closed part of the drum shaped hub protruding fro its face is a tube running horizontally almost its full length, the tube is hollow and aligns with a hole in the closed end of the drum shaped hub and is fixed and will only rotate with the drum shaped hub. The hole running down the centre is of a size that will allow the spindle and bearings to fit tightly within it. When assembled to the spindle the whole will rotate freely upon the bearings.

At the closed end of the drum shaped hub between the tube and the out body is a series of holes. these holes accept a series of pins, these pins are permanently affixed to the holes and do not rotate independently of the drum shaped hub.

Fitted to these pins are a series of gears. The gears have holes drilled in them to such a size that they run freely on these pins and all rotate independently of each other as they are spaced so they do not touch one another.

A plate with holes to correspond with the pins and centre tube is also fitted to reduce the possibility of the pins bending in there length.

A gear is fitted to the end of the spindle and held in place by a metal key that fits into a slot on the spindle and a reciprocal slot within the centre hole within this gear. By this method the gear is affixed to the spindle,and as before stated the spindle is fixed and will not rotate thus this gear will not rotate either.

This gear is of a size that means it fits within and is in permanent mesh with the gears mounted on the pins with in the drum shaped hub.

A large gear with inward facing teeth is mounted on one side to a face plate,this gear is of a size and pattern as to allow it to surround and mesh to within good engineering tolerance upon the gears on the pins within the drum shaped hub.

On the outer side of the face plate of the large gear is attached the secondary or inner annula hand-grip. In the centre of the face is mounted a bearing that runs freely on the axle.

The whole is held in place by a bolt and thrust washer,the bolt aligns with a threaded hole drilled into the end of the spindle It can be seen When assembled as described the inner hand-grip when turned rotates the large gear with inward facing teeth, this causes the gears on the pins within the drum shaped hub to rotate against the centre gear upon the spindle.

As the gear upon the spindle is affixed and will not rotate,the drum shaped hub is driven round by means of the pins attached to its closed face,as the gears upon those pins orbit the fixed centre gear.

As the drum shaped hub is attached to the road wheel rim by radial spokes the road wheel therefore is rotated.

As the gearbox is always in drive it will run in forward or rearward motion equally as well. As two of these gearbox's are fitted per wheel chair it is possible to rotate each independently to facilitate turning and also a mechanical assistance in reducing speed or braking.

As the second hand-grip is permanently in a reduction ratio at all times the removal of the hand from the normal hand-grip and using the hand-grip of the gearbox is a simple and at all times a safe task and causes a different speed ratio between both hand-grips.

A specific embodiment of the present invention will now be described solely by way of example,with reference to the accompanying drawings in which: Figure 1 is an enlarged section through the hub of the wheelchair wheel Figure 2 is an exploded view of the component parts of the geared hub,not necessarily in order of assembly.

Figure 3 shows the wheel chair road wheel and the two hand grips fixedly attached.

Description of the preferred embodiments According to figure 1 there is provided a metal hub 10 which is fixedly attached to a pneumatic or other type wheel of a conventional hand propelled wheel chair,not shown. The hub 10 is upon and free to rotate about a solid high tensile steel spindle 14/15 which is itself fixedly attached to the frame work of the wheel chair (not shown) through the screw threaded portion 15.

The hub 10 rotates on roller or oilite bearings 16 for example.

The hub 10 is attached to the road wheel by radial spokes 21.

The lip 13 on hub 10 is drilled to accept the radially affixed spokes. Pins 19 pass through and are affixed to the rear face of hub 10 these pins are held from distortion by plate 11.

On the pins 19 is located and running freely the smaller gears 18.Gears 18 are in constant mesh with gear 17. Gear 17 is held by a key way and thus affixed to the spindle 14/15.

Gears 17 are then themselves encompassed by gear 20 which in turn holds all the gears in constant mesh.

Gear 20 is closed at one end facilitating the fitting of a hand-grip ( not shown) The gear assembly 20 is held in place by the washers 23 and 25 these washers in turn are protected from rotating independently by key 29 and key way 30. These washers are in turn supported by a bearing surface in the centre of gear plate 20. The whole is held together and trapped between bolt 24 and at the wheel chair attachment end by washer 27.

FIGURE 2 The exploded view of figure 2 shows the same components as afore mentioned. The spindle can now be seen as a whole and separate unit, with 15 the spindle 16 the bearing surface 27 the washer 28 the keyway for gear 17 the threaded hole 26 for bolt 24.

It should be obvious from figure 2 and by comparison with figure 1 that rotation of gear ring 20 will cause gears 18 to orbit gear 17. As gear 17 is affixed to spindle 14 15 and both are prevented from rotating the directional force is taken via pins 16 to hub 10 and thus to the wheel chair road wheel.

FIGURE 3 Reference is now made to figure 3 which illustrates any wheel chair road wheel 31 to which is fixedly attached the usual push-grip 32.

Of smaller peripheral diameter than the hand-grip 32 is provided a second hand-grip 33 which is fixedly attached to the gear assembly 20 within the hub 10 It can therefore be seen that the road wheel 31 can be rotated by hand-grip 32 or by hand-grip 33. Hand-grip 32 has a direct influence on the road wheel 31 but hand-grip 33 has influence only on the gear 20 and the gear train 20,18,17 which produces a speed differential reduction of a maxilul 50 percent.

The embodiment of this invention may be fitted to existing manually propelled wheel chairs or provide with wheel chairs which are newly constructed.

An alternative embodiment would be a hub as previously described in design and construction as a self contained unit not radially spoked but permanently affixed to a normal and common wheel chair road wheel by means of screws or bolts or any permanent fixings.

Claims

1. A fixed ratio single speed geared hub incorporated into the centre of a wheelchair wheel incorporating its own integral push rail 2. A geared hub as claimed in claim 1 with one gear ratio and the ability to go forwards and backwards with no free wheel or coasting ability is fitted to a hand propelled wheelchair wheel at its centre and the wheel is fitted to the wheel chair in its normal manner one per side. 3. The hub as claimed in claims 1 and 2 incorporates a gear box that contains a reduction system with a single fixed ratio and no secondary ratios and no gear change systems 4. Wheelchair wheel fitted with a geared hub as claimed in claims t 2 and 3 incorporates the hand rail as claimed in claim 1 is a separate hand rail from that already fitted to the wheel chair wheel and will rotate separately from that hand rail. Amendments to the claims have been filed as follows CLAIMS

1. A hand propelled wheelchair, comprising a frame carrying a seat and supported by road wheels in which a hub of each road wheel carries a handwheel drivingly connected to the hub through a filed ratio single speed gear train within the hub.

2. A hand propelled wheelchair as claimed in claim 1 with the ability to go forwards and backwards with no free wheel or coasting ability.

3. A hand propelled wheelchair as claimed in claim 1 or 2, in which the gear train within each hub is a reduction gear train.

4. A hand propelled wheelchair as claimed in claims 1, 2 or 3, including an annular handwheel attached near the periphery of each road wheel for exerting a direct manual driving force to the wheel which primary handwheel is a separate handwheel from that already fitted to the wheelchair hub.