GB2364282A - Manual propulsion system for a wheelchair - Google Patents

Abstract

The propulsion system comprises a pair of independent manual control units (24) mounted on arcuate tracks on backplates one on each side of the chair, adjacent to a respective rear wheel. By operation of a button (34) in the handle (26) of each control unit (24) and by pushing or pulling the handle, the control unit engages a cam 50 (Fig. 6B) with the adjacent wheel to establish a driving connection, whereby movement of the control unit along the arcuate path will cause chair movement. With the button (34) in one position, the control unit disengages from the wheel at the end of a forward stroke, allowing it to return for a further stroke, by pivoting of the cam (50) on an axle (46) with engagement of a bolt (51) in part of a groove (52). Button movement to a second position pivots the cam (50) for one-way reverse drive, and to a third position for cam-wheel engagement in both directions, e.g. for braking, steering.

Description

2364282 AIDS FOR SELF-PROPELLED VEHICLES This invention relates to aids

for self-propelled vehicles, such as wheelchairs. Reference hereinafter to 5 "wheelchairs" is to be understood as including all forms of selfpropelled vehicles.

There has been a long-term need for an improved method of propelling a manual wheelchair. Many people are confined temporarily or permanently to wheelchairs, and current 10 estimates suggest that there are some 580, 000 manual wheelchairs in use in the United Kingdom alone. The conventional method of using the hands on the tyres or hand rims has many disadvantages. obvious disadvantages of the conventional method of manual propulsion are that it is not 15 ef f icient, is abrasive to the hands, is difficult f or those with limited hand mobility and is not clean. Additionally, recent medical studies indicate that long-time users of wheelchairs experience physiological problems in the upper limb area, particularly the shoulders.

20 It is an object of the present invention to provide an improved method of propelling a manual wheelchair, which is more efficient than the conventional method, which is cleaner, less abrasive to the hands, is easier for those with limited hand mobility and is inherently safe. The present invention 25 offers users a more effective means of moving themselves in comfort, whilst remaining fit, healthy and with potential for increased independence.

It is a further object of the invention to provide an accessory which can be adapted to fit almost any type of 30 manual wheelchair. This means that the accessory can either be purchased with the chair as new, or bought as an accessory and retrofitted at a later stage.

It is a further object of the invention to provide an accessory which when fitted to a wheelchair does not impede the conventional method of using the hands on the tyres or 5 hand rims, as this is quick and convenient for small movements, for example indoors. The accessory of the present invention is unobtrusive in conventional use, but offers comfort and a more efficient and healthier means of manual propulsion, braking and steering of the wheelchair.

10 It is yet a further object of the invention to provide a wheel chair accessory which reduces the likelihood of injury in the upper limb area, particularly the shoulders. The accessory of the present invention reduces the likelihood of such physiological problems and provides a comfortable means 15 of manually propelling the wheelchair while offering integrated steering and braking from the same manual control grip. With the accessory of the present invention, wheelchair users have an increased potential for independent movement, with less reliance on the need for a carer and for carer 20 support.

Broadly in accordance with the present invention there is provided a device for use in the propulsion of a manual wheelchair, comprising, on each side of the chair, means defining an arcuate track, and a manual control unit mounted 25 on the track and arranged to be displaceable in an arcuate path following said track, the manual control unit including means engageable with the adjacent wheel of the chair under the control of the user via the control unit to establish a driving connection between the unit and the wheel, whereby 30 movement of the control unit forwards and backwards along the arcuate path will drive the chair.

Preferably, the manual control units offer integrated driving, braking and steering of the wheelchair.

In a preferred embodiment, the device comprises two independent, substantially identical hand control units, each 5 mounted on a respective fixed running track which is mounted at the side of the chair via respective backplates set between the drive wheels and the seat. These backplates are designed specifically for individual chairs so that the device can be retrofitted to wheelchairs of any design.

10 Preferably, a three-position button at the top of each hand control unit allows the user to select whether the push/pull action of the arm on the hand control unit moves the chair forwards, backwards, or a combination of both, as is required for kerb jumping, etc.

15 The device of the present invention embodies a mechanical only structure which, in a preferred embodiment, positions a cam over the wheel, which in turn engages onto the tyre for drive when the hand control unit is pushed or pulled. This cam is arranged to disengage when the user reverses motion on 20 the control unit, allowing the unit to return for another stroke on the bearing track with minimal friction.

In a preferred arrangement, the device also incorporates a separate handbrake facility and quick-release track stops which allow the user to restrict the length of stroke of the 25 device. This can be beneficial to some users.

Both hand control units can be removed from their respective bearing tracks, thereby to permit easy stowage of the wheelchair. Removal of the units can be effected by releasing one of the aforesaid track stops and sliding the 30 unit from its track.

In order that the invention may be more fully understood, one presently preferred embodiment of device in accordance with the invention will now be described by way of example and with reference to the accompanying drawings. In the drawings:

Fig. 1 is a diagrammatic side view of a wheelchair S equipped with hand control units in accordance with the invention; Fig. 2 shows hand control units in accordance with the invention fitted to a typical lightweight wheelchair; Fig. 3 is an external view of one of the hand control 10 units, on an enlarged scale, with its cover in place; Fig. 4 is an enlarged isometric view, partly broken away, showing the internal structure of the hand control unit of the present invention; Fig. 5 is a side view, partly broken away, of the hand 15 control unit of Fig. 4; Fig. 6A shows the operating cam of the hand control unit of Figs. 4 and 5 from below; Fig. 6B is a front view of the operating cam; Fig. 7A is an isometric view of one of the quick-release 20 stop units to be fitted to the bearing track to limit the stroke of the hand control unit; and, Fig. 7B is a sectional view through the stop unit of Fig. 7A.

Referring first to Figs. 1 and 2, these show a typical 25 lightweight wheelchair comprising a seat 10, a support frame 12, rear wheels 14 and front wheels 16. Each of the rear wheels 14 is fitted with a tyre 18 and with a hand rim 20.

Between each rear wheel 14 and the seat 10 there is fitted a backplate 22 which lies parallel to the plane of the 30 rear wheel 14 and extends through slightly more than 90'. Mounted above the backplate 22 and the rear wheel 14, on each side of the wheelchair, there is provided a hand control unit indicated generally at 24.

In general terms, the mirror-image left-hand and righthand control units 24 each operate a cam and control mechanism 5 which grips the tyres 18 when pressure is applied to the handle of the unit. A switch in the top of the handle grip allows one to switch between forward and reverse, or into a -joggle" mode which can be used to jump kerbs, etc. By applying pressure either forwards or backwards to the hand 10 grip, and with the switch in its required position, the unit will engage and drive the wheel 14 in the direction required. The driving cam automatically lifts itself off the tyre 18 on its return stroke, before engaging with the tyre again for the next stroke. As compared with the distance from the centre 15 of the wheel 14 to the hand rim 20, the greater distance f rom the centre of the wheel to the hand grip provides increased mechanical advantage. Therefore, less energy is expended in moving the chair over an equivalent distance than by pushing by hand directly on the tyre or hand rim.

As will be described in more detail hereinafter, both hand control units 24 are mounted on respective bearing tracks fixed to the respective left-hand and right-hand backplates 22.

The hand control unit, in its movement, follows the 25 periphery of the tyre on the bearing track in an arcuate path and pressure on the hand control, either forwards or backwards, transfers grip to the tyre 18 by way of a locking cam which is enclosed within the moulded housing of the hand control unit. The travel of the hand control unit 24 can be 30 limited at the upper and/or lower ends of the bearing track by the use of quick-release locking blocks or stops which are able to be located in a series of holes around the track. This allows users with poor abdominal balance to limit the leaning forward which is sometimes necessary in order to move the wheelchair conventionally. The quick-release locking S blocks or stops enable the user to remove these quickly for stowage purposes. The backplates 22 remain mounted on the wheelchair frame 12, but can easily be moved to allow adjustment of the rear wheels 14 when setting the centre of balance or the height of the seat 10.

10 Reference is now made to Fig. 3 which is an external view of one of the hand control units 24. The hand control unit comprises a hand grip 26 and a moulding 28 which covers the controls and drive mechanism. This moulding 28 provides a safe and protective shell which can also house a trip computer 15 unit linked to a display 30. The small computer unit which is housed within the unit 24 allows more athletically minded users to monitor their speed, distance travelled, etc. via the display 30 which can be an LED display for example. Only one of the two hand control units 24 needs to be provided with the 20 computer unit. The computer unit is triggered by a wireless connection to a transmitter mounted on the associated backplate 22 and adjacent to a magnet mounted on the adjacent wheel 14. Preferably, the right-hand unit 24 houses the computer, with the left-hand unit being used for other 25 optional accessories. All controls for the computer unit can be set without removing the hand from the grip 26. The grip 26 can itself be altered in shape from that shown in Fig. 3. For example, it could be a T- bar arrangement and/or include strapping restraints for users who have limited use of their 30 hands or fingers. Desirably, the grip 26 has a profiled shape and is produced from a low Shore hardness neoprene material to maximise comfort. A gaiter 32 allows movement of the floating hand grip 26, enhancing comfort in use. The hand control unit 24 includes a sealed bearing set which is mounted to facilitate its fitting to the bearing track onto which it 5 is slid into position. The moulded cover 28 protects both the user and others when in use and adjustable pins can be set adjacent to the bearings in order to be able to position the unit accurately on its bearing track. Adjustment screws within the main housing allow height adjustment to accommodate 10 tyres of different profile.

Fig. 4 shows the internal details of the hand control unit 24. In the centre of the hand grip 26 is a control button 34. This control button 34 has two pre-set positions and a third position in which it can be held manually by the 15 user, as will be described in more detail hereinafter. By pressing the control button 34, a toggle 36 is depressed and rocks to one side. On release of the control button the toggle latches onto a hook on one side of an insert 38, in the upper or lower position. The reverse occurs when the button 20 34 is pressed again, and so on. The toggle 38 is held by either an upper or lower hook with back pressure from a sprung actuator rod 40. The actuator rod 40 passes through the centre of a hand grip mount 42 and rests on the upper face of a sprung gear lever 44. The gear lever 44 slides over a main 25 pivot bolt 46 which passes through an inner housing 48 which serves as a chassis for the unit. The main pivot bolt 46 also passes through a hole 49 in a cam 50. At the lower end of the gear lever 44 is a cam pivot bolt 51 which extends into a 3armed hole 52 (Figs. 6A, 6B) in the cam 50. As shown most 30 clearly in Figs. 6A and 6B, the cam 50 is generally triangular in shape with at each end a serrated portion 53 for engagement with the tyre 18. Bolted into place on the unit below the cam 50 is an assembly which comprises the means by which the hand control unit 24 is fitted to the bearing track on the backplate 22. A bearing support bracket 54 is bolted to the 5 inner frame of the hand control unit and allows vertical height adjustment of the cam 50 relative to the tyre 18. Preferably, a clearance of 2 to 3 mm between the cam 50 and the tyre 18 is set. The bearing support bracket 12 carries a pair of bearings 56. The hand control unit 24 is slid onto 10 the backplate mounting track by sliding the unit onto the track from the rear of the wheelchair, with one bearing pair 56 above the track and the other pair below the track. The unit can then be locked in place by means of quick-release stops, which are f itted to the upper and lower ends of the 15 track to suit the length of stroke which is desired.

once the hand control unit 24 has been loaded onto its track, secured by means of the quick release stop units, and any positional adjustments have been made, the device is then ready for use.

20 The control button 34 on the top of the hand grip has two pre-set positions, and a third position in which it can be held in position manually by the user, for safety considerations. The three positions correspond to the location of the cam pivot bolt 51 in the respective arms of 25 the 3-way hole 52 through the cam 50. The positions are as follows:

Position 1: Button up (forward drive). Pushing on the hand grip engages the drive cam 50 with its serrations 53 against the tyre 18, and further pushing drives the wheel 14 forwards. Pulling back on the hand grip releases the cam f rom the tyre, in preparation for another forward stroke Position 2: Button down (reverse drive) Pulling on the hand grip 26 engages the drive cam 50 with the 5 tyre 18. Further pulling drives the wheel 14 in the reverse direction. Pushing the hand grip 26 forwards at the end of the drive stroke releases the drive cam 50 from the tyre, ready for another reverse drive stroke.

10 Both the forward and reverse button positions can be switched by pressing and releasing the button once, when the hand grip 2G is in its neutral (normally vertical) position.

Position 3: Button fully down (joggle mode). By pressing 15 the control button 34 down when the hand grip 26 is in the neutral (vertical) position, the user can lock the drive cam 50 in both forward and-reverse modes simultaneously. This allows one to "joggle" the chair onto the rear wheels 20 14, as is required for kerb Jumping, for example. Such use does require a degree of skill, and so for reasons of safety, constant finger pressure on the button 34 is required for this mode of operation.

25 Returning to a consideration of Fig. 4 and the motion within the hand grip unit, it is to be noted that the geometry allows the hand grip to be pushed overcentre, and if the control button 34 is in its "button up" position (position 1 above), the cam pivot bolt 51 passing through the cam drive 30 applies pressure to the cam, causing the serrated teeth on the cam to engage with the tyre. Further pushing of the hand control unit results in the whole unit rolling on its bearings around the track in the desired direction. The cam 50 is normally held in a central position away from the tyre, by a spring at the front and a further spring at the rear, the 5 springs being seated and anchored against the inner housing 48. The cam 50 is shown in more detail in Figs 6A and GB. The upper arm of the hole 52 in the cam 50 corresponds to driving the chair forwards, and is designed to allow the hand grip to be pulled back at any angle without f orcing the cam 10 onto the tyre, i.e. causing sudden and unsafe braking. If the control button 34 is in "Position 211, i.e. is pressed down, the above process is reversed, for drive in the reverse direction. Pressing the control button 34 will release the toggle 36 which, on being thrown over centre, will catch the 15 opposite upper or lower hook in the handle, thus reversing the drive mode. This is how the user is able to apply progressive braking, by pressing the control button once and gently applying pressure in the opposite direction. Exactly the same mechanism and process is used to steer the wheelchair. In 20 other words, if one is travelling forwards and wishes to turn to the right, the control button 34 is pressed once and released. The user then gently pulls back on the hand control unit, which applies the cam to brake on that side. With no action on the left-hand control grip, the chair will then veer 25 to the right, by an amount which is dependent on the pressure applied. Thus, the provision of two independently operating hand control grips 24 means that one can have the drive, braking and steering all incorporated into one unit without the need to remove the hands f rom the hand grips. This is 30 very useful for those who have restricted hand or lower arm movement, for example some tetraplegics.

If the control button 34 is fully depressed and held manually, in which position there is no latch, for safety reasons, the cam pivot bolt 51 is moved into its lowest position by the actuator rod 40, i.e. into the downwardly 5 extending arm of the 3-way hole 52 in the cam. It is in this state where the user has immediate drive for both forward and reverse directions with no cam lift, i.e. the drive appears to have immediate effect in both directions, enabling the user to cope with kerb stones by balancing the chair on its rear 10 wheels. In order to achieve this, both the left-hand and right-hand control units must have their buttons depressed fully.

If the user does remove both hands from the hand grips 26, the units will be self centring, with no contact with the 15 tyres, and will gently follow the bearing tracks under the weight of the hand control units until they hit the forward stops on the tracks. In this position the hand control units will be below the seat height, thereby aiding transfer of the user to and from the wheelchair. However, the hand control 20 units will still be easily retrievable when required.

Figs. 7A and 7B show one of the stops which are fitted to the bearing tracks. The stop is indicated generally at 60. Two stops 60 are fitted to each side of the wheelchair, one upper stop and one lower stop. They are specifically designed 25 to be fitted at various points around the bearing tracks to suit the user. Thus, they can be f itted at the extreme ends of the bearing tracks or at intermediate positions which are provided at intervals along the tracks. Each stop comprises a body 61, and a button serving as a locking plunger 62 which, 30 when pulled by the user, causes the spring-biassed retraction of a movable pin 64 in the side of the stop and which, in conjunction with a fixed lower pin 66, locks the stop unit quickly onto the bearing track. When it is locked into place on the track it prevents the hand control unit 24 from passing. This sprung mechanism can be fitted and removed very 5 quickly, and with one hand, thereby enabling the wheelchair user to remove it or reposition it as required.

The progressive braking which is made possible by the device of the present invention is extremely advantageous, particularly as it is incorporated into the same unit which 10 enables driving and steering. By incorporating this progressive braking into the hand control units, the user can discard the often ineffective and inaccessible brakes which are provided on many wheelchairs.

The flexibility of attachment of the hand control units 15 of the present invention will not hinder those wheelchairs which are foldable or which have removable wheels, as is the case for most lightweight chairs. The hand control units of the present invention have equal benefit on lightweight chairs or standard hospital wheelchairs. The device of the present 20 invention is designed to be fitted to the majority of manually propelled wheelchairs, simply by fitting chair-specific backplates 22 to accommodate different frame designs. This flexibility means that the accessory is available both for new wheelchairs and also for retrofitting to existing chairs.

The following summarises the benefits and advantages of the accessory provided in accordance with the invention.

Short term and long term physiological strain in propelling the wheelchair is reduced, due to the flatter drive loci which are followed by the hand control units.

The provision of integrated controls for driving, steering and braking the wheelchair, all within the hand control unit, allows the hands to remain on the hand grips at all times.

The increased mechanical advantage which is provided by the accessory of the present invention requires less 5 effort to propel and manoeuvre the wheelchair, even allowing for the added weight of the units.

As the hands are not used on the hand rims or tyres to propel the wheelchair, it is thus cleaner and less abrasive on the hands.

10 A simple one-button control on the hand control grip is all that is required to change direction, carry out braking movements and steer.

The accessory still allows the user to propel the wheelchair by normally accepted means, i.e. by pushing 15 the tyres or hand rims in the direction required, if desired.

Quick release wheels, where fitted, can be detached without removing any of the components of the hand control units.

- The accessory can be used with the majority of manually propelled wheelchairs, and only requires the fitting of backplates which are appropriate for a particular wheelchair frame.

- As the accessory is operated manually, it ensures that 25 the user is gaining upper body exercise, which is essential to those users who are unable to leave their wheelchairs.

- Existing brake units, which are generally ineffective and dif f icult to reach, can be removed, or not taken as an 30 option, if purchasing a new wheelchair.

- The length of driving stroke of the hand control units can be adjusted to suit the user, by moving the position of the stops, which is particularly useful where body movement is restricted in some way, for example due to weak abdominal muscles.

s A clothes guard can be incorporated into the design to give protection for clothes from dirty or wet wheels or from the hand control units themselves.

The hand control units can be rapidly removed from the wheelchair, and indeed using only one hand. This enables 10 the user quickly to dismantle the chair, for example for loading it into a car, with little or no additional effort. The hand control units can be used on folding chairs without restriction.

The hand control units are designed to be strong and is light, and require minimal maintenance.

The hand control units provide for progressive braking, and also provide a permanent handbrake facility.

The hand control units are fully adjustable to allow the use of different tyre profiles, aided by a self-centring 20 sprung cam drive mechanism. This overcomes any wheel or tyre distortion which could adversely affect the operation of such a device.

Because the provision of hand rims is no longer necessary with the hand control units of the present invention, the 25 hand rims can be removed or not provided, thus reducing the width of the wheelchair overall and enabling improved access through doors, etc.

Claims (14)

CLAIMS:

1. A device for use in the propulsion of a manual wheelchair, comprising means defining an arcuate track adjacent to a wheel, and a manual control unit mounted on the 5 track and arranged to be displaceable in an arcuate path following said track, the manual control unit including means engageable with the adjacent wheel of the chair under the control of the user via the control unit to establish a driving connection between the unit and the wheel, whereby 10 movement of the control unit forwards and backwards along the arcuate path will drive the chair.

2. A device as claimed in claim 1, in which the manual control unit provides integrated driving, braking and steering of the wheelchair.

15

3. A device as claimed in claim 1 or 2, in which the manual control unit is mounted on a fixed running track which is mounted at the side of the chair on a backplate set between the adjacent wheel and the seat.

4. A device as claimed in claim 3, in which the 20 backplate is parallel to the plane of the adjacent wheel and extends through about 900.

5. A device as claimed in any preceding claim, in which a three-position switch is provided at the top of the manual control unit to allow the user to select whether the push/pull 25 action of the arm on the manual control unit moves the chair forwards, backwards, or a combination of both.

6. A device as claimed in any preceding claim, in which the control unit operates a cam mechanism over the wheel, which in turn engages onto a tyre for drive when the control 30 unit is pushed or pulled.

7. A device as claimed in claim 6, in which the cam mechanism is arranged to disengage when the user reverses motion on the control unit, allowing the unit to return for another stroke on the track with minimal friction.

8. A device as claimed in any preceding claim, in which 5 the manual control unit is removable from the track.

9. A device as claimed in any preceding claim, in which the control unit incorporates means to permit progressive braking.

10. A device as claimed in any preceding claim, which 10 includes quick-release track stops to enable the length of stroke to be set.

11. A wheelchair comprising a seat, a support frame, rear wheels, front wheels, and a pair of devices as claimed in any preceding claim mounted adjacent to the respective rear 15 wheels.

12. A wheelchair as claimed in claim 11, having two independent, substantially identical control units, each mounted on a respective track on a backplate set between the adjacent rear wheel and the seat.

20

13. A device for use in the propulsion of a manual wheelchair, substantially as hereinbefore described with reference to the accompanying drawings.

14. A wheelchair substantially as hereinbefore described with reference to the accompanying drawings.