GB2111000A

GB2111000A - Wheelchair attachment

Info

Publication number: GB2111000A
Application number: GB08229757A
Authority: GB
Inventors: Albert Edward Frederick Dudley
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-10-20
Filing date: 1982-10-18
Publication date: 1983-06-29
Also published as: AU1187983A; GB2111000B

Abstract

An attachment or arrangement for enabling a wheelchair (1) to climb a kerb (31) comprises a unit (25) which is readily releasably attachable to the side frames (2) of the wheelchair. The unit includes a wheel (26) carried by support arms (28) which are connected to a main support bar (30) which is attachable to the said frames. The wheel (26) overlaps the castorable front wheels (21) of the wheelchair (1) and has its axis of rotation in the plane containing the castoring axes of the front wheels (21). The wheel (26) is normally not in contact with the road. When the wheelchair nears a kerb (31) the wheel (26) rides up the kerb and in so doing lifts the front wheels (21) whereby the wheelchair is able to mount the kerb. <IMAGE>

Description

SPECIFICATION Wheelchair attachment This invention relates to wheelchairs or other articles required to run on a roadway, or other surface and having surface engaging running wheels.

In the case of wheelchairs it is conventional practice to provide such chairs with motor driven rear wheels and front wheels which are free to rotate and which are castor mounted so that the front wheels are able automatically to move to the required setting during the use of the chair and throughout any control movements induced by the user such as changeover in direction of movement of the chair or turning movements.

In use it has been found that an inherent difficulty arising in the use of the known wheelchairs is that the wheelchairs are not able to mount or climb an abrupt step such as a kerb defining the transition between a roadway and a pedestrian walkway.

It is an object of the present invention to provide a wheelchair with means whereby the user is able to negotiate or climb abrupt steps such as kerbs having a step height less than a predetermined maximum for a particular wheelchair construction and construction of the climber means.

Broadly, according to a first aspect of the invention there is provided an arrangement for enabling a wheeled unit or article such as a wheelchair to mount or climb an abrupt step or incline such as a kerb, the arrangement including a rotatable member, wheel, roller or like rotatable article which is arranged to be so positioned with respect to the remainder of the wheeled unit that the working surface thereof is able to engage with and at least in part negotiate the step in advance of the engagement of the leading wheels of the wheeled unit with the said step.

Preferably, the rotatable member has a radius of curvature greaterthan that of the leading wheels, and is so mounted that the working surface thereof is maintained out of contact with a surface upon which the leading wheels rest or travel.

According to a second aspect of the invention a kerb or other abrupt step climber for use with a wheeled article such as a wheelchair includes at least one wheel, roller or the like, which is adapted for mounting to the wheeled article such that it is held out of running cntact with a surface upon which the leading wheels of the wheeled unit rest or travel and further such that it is able to co-operate with a said step or the like in advance of the leading wheels.

Preferably, said wheel, roller ofthe like is mounted between the side frames of the wheeled unit whereby the climber does not increase the transverse width of the wheeled unit.

Conveniently, the wheel is mounted from a support unit which is adapted to be readily mountable to or removable from the wheeled article such as a wheelchair.

Conveniently, the axle of the wheel is carried from side by side arms which are themselves carried from a support bar adapted for connection to the side frames of a foldable motor driven wheelchair.

For a better understanding of the invention and to show how to carry the same into effect reference will now be made to the accompanying drawings in which Figure 1 is a highly schematic representation of a side view of a wheelchair incorporating electrically driven rear wheels; Figure 2 is a schematic front view of the wheelchair of Figure 1; Figure 3 is a view of a wheelchair of a construction similar to that of Figures 1 and 2, but incorporating a step or kerb climber unit incorporating the features of the invention; Figure 4 is a front view of the arrangements of Figure 3; Figure 5 is a fragmentary perspective view of a wheelchair fitted with the climber unit of the invention; and Figures 6to 9 are diagrammatic representations of various stages of the climbing the step to be mounted, the Figures showing the positions of the climber wheel and the wheeled vehicle front wheels during the climbing.

Referring now to the drawings and more particularly to Figures 1 and 2, the wheelchair 1 shown therein includes side frames 2 having front and rear transverse rails. These side frames 2 are connected to each other by a pivot 5 and to the frames 2 by pivot connections 5A. An arm rest forming frame unit 6 is mountable to each side frame 2 with each such unit 6 being mounted by way of socket type connection means 7 provided upon the side frames 2.

Each unit 6 includes a side panel 7A. The rear uprights 8 of the units 6 provide support for a flexible back rest sheet 10 formed of plastics, fabric or the like. The uprights also provide at their upper ends handles 9 for enabling the chair to be manually controlled.

Each of the side frames includes an upper rail 11, these rails being used as the means of mounting the end regions 12 of a flexible seat forming sheet 13.

The side frames also include intermediate transverse rails 15, with each of the latter including a generally rectilinear section 16, and a generally L-shaped section 17 that extends in prolongation of the section 16 but at a higher level to connect with the front upright 18 of the associated side frame 2.

A main motor driven wheel 19 is mounted from each frame 2 by way of a combined electric motor and transmission arrangement 20.

The wheelchair 1 also includes braking arrangements but these are not shown in the Figures.

The lower end regions of the frame front rails 18 are utilized to mount castorable front wheels 21.

Each of these front wheels 21 is rotatably mounted by a suitably shaped fork 22 which is rotatable about a vertical axis 22A whereby the front wheel is able to undergo the castoring action required for the purposes of facilitating the control and steering of the wheelchair by the user.

Afoot rest 23 is carried from a support arm 24 extending from the associated upright 18. Each footrest 23 is movable between a position of use and a retracted position when not required for use.

Control arrangements (not shown) are provided for enabling the user of the chair selectively to drive the wheelchair 1 backwards or forwards as desired, and also to steer the chair by means of a differential drive of the main wheels 19. In practice, a battery carriage (not shown) is provided at the rear of the wheelchair 1.

As so far shown and described the wheelchair 1 is not capable of mounting or climbing abrupt steps in the terrain over which the wheelchair travels. A very common occurance of abrupt level changes is the transition between a roadway and the adjacent pedestrian walkway. Such transitions are commonly called kerbs.

Referring now to Figures 3 and 4 of the drawings, these Figures are generally similarto Figures 1 and 2, except that Figures 3 and 4 illustrate the wheelchair of Figures 1 and 2 fitted with a step or kerb climber unit 25 incorporating the features of the present invention.

As will be seen the climber unit 25 essentially comprises a wheel 26 located adjacent the front of the wheelchair and between the front wheels 21, conveniently at the medial plane of the wheelchair.

The wheel 26 is so carried by a support unit 27 that it is normally or usually out of contact with any surface upon which the wheelchair is resting or travelling and such that the leading part of the wheel 26 is slightly in advance of the leading parts of the castored wheels 21. The relative positioning ofthe wheels 21 and 26 will be considered in detail hereinafter.

The support bracket 27 comprises two similarly shaped arms 28 connected at one end with the axle 29 of the wheel 26 and at the other ends with a transverse main bar 30 which is itself adapted for connection to the forward end regions of the bottom transverse rail sections 16 of the side frames 2.

As shown the transverse bar 30 includes pins or the like 30A which are able firmly to engage with the forward facing ends of the sections 16.

If the side frames 2 are not of the specific form shown in the Figures 3 and 4 the transverse support or main bar 30 may be connected to the side frames 2 by means of brackets (not shown) which allow ready mounting to and ready removal of the climber unit 25 from the wheelchair 1. It will be understood that whatever, form of mounting is used for the climber unit 25 it is necessary that the unit 25 be removable as required so that, for example, the wheelchair may be folded.

In a particular arrangement the climber unit supports i.e., pins 30A may be held in place by retaining bolts have manually operable heads such as 'wing nuts'.

In practice, the relative positioning and diameters of the wheel 26 and the wheels 21 is of great importance.

In the first place the axis of rotation of the wheel 26 needs to be located in or very close to the plane containing the vertical axes of castoring of the wheels 21 that is the plane containing the axis 22A of each wheel 21.

In addition, the relative diameters of the two wheels need to be such that, looking from the side of the wheelchair the cusp or spinode formed by the overlapping or meeting region of the curved form of the wheels 21 and 26 (shown at 26A of Figure 3 and Figures 6 to 9) needs to be as shallow as possible.

In a practical situation, bearing in mind that an average kerb height of 3 to 4 inches and front wheels of a conventional diameter of 8 inches the diameter of the wheel preferably lies in the range of 10 and one half inches diameter and 12 and one half inches diameter with a preferred diameter range of 11 to 12 inches.

To achieve this a convenient practical range of settings for the height of the axis of the wheel 26 above ground level is within a range 6 to 7 inches with a particular range lying between 6 and one half to six and three quarter inches.

With the arrangement as discussed it has been found that an average kerb can be readily mounted with out it being necessary for the user of the wheelchair to have to accelerate as is the case with kerb mounting arrangements in which the mounting wheel is located well in advance of the wheelchair front wheels. Also it has been established as a result of wide testing that the positioning of the climber wheel in the manner proposed by the Applicant the castorable wheels 21 are most unlikely to move into a bridging angle relative to the kerb during a kerb mounting operation as a consequence of the wheelchair user not approaching the kerb in a direction exactly at right angles to the run of the kerb.

With the above discussed arrangements it will found that the wheel 26 is able to contact and co-operate with a step i e., kerb, in advance of the contact of the front wheels 21 with the same kerb, and also such that by the time the wheel 26 has been advanced by the forward motion of the wheelchair into co-operation with the upper surface of the kerb the front wheels 21 will have been rolled into a position in which they are in contact with the front surface of the kerb and are possibly in the process of negotiating the edge of the kerb. The particular instant at which this occurs will be related to the diameters of the wheels 21,26, the height of the kerb and the resiliency or compressibility of the material forming the tyres of the wheelchair. Also in the event of inflatable tyres the inflation pressure will become a relevant factor.

Referring now to Figure 5 this illustrates to a larger scale the construction and fitting of the climber unit 25 to the framework of the wheelchair. As will be seen the axle 29 of the wheel 26 is carried from the support arms 28 which are in turn mounted from the transversely directed main bar 30. This bar 30 is supported by the rail sections 16 of the two side frames 2.

Referring now to Figures 6 to 9; Figure 6 is intended to depict the situation when the climber unit wheel 26 has just contacted the leading or facing edge of the kerb 31. It will be noted that the front wheels 21 of the wheelchair are still in contact with the surface i.e., the road 32. As the wheelchair 1 moves forward the climber unit wheel 26 rolls progressively onto the kerb 31. At the position shown in Figure 7 the climber unit wheel 26 is just moving onto the kerb upper surface 33 and the front wheels 21 are by that time in contact with the kerb edge of the kerb 31. Whether or not the wheels 21 actually lift from the road 32 will depend upon the various factors above discussed such as the relative diameters of the wheels 21 and 26 and the relative positioning of their axes of rotation.Other factors such as the extent of relative tyre crushing will have a bearing upon the actual situation.

Further forward movement of the wheelchair towards the kerb 31 causes the climber unit wheel 26 to move up onto the upper surface 33 of the kerb 31.

This action will cause the front wheels 21 to lift up towards the upper surface 33 whilst rolling against vertical surface of the kerb. This is schematically shown in Figure 8. During further forward movement of the chair the lift of the front wheels 21 towards the upper surface of the kerb 31 will lift the climber unit wheel 26 away from contact with the surface 33. This is shown in Figure 9.

It will be understood that the above mentioned relative positioning of the wheels in relation to the diameters thereof is intended to ensure that at all times a positive support is provided for the front regions of the wheelchair, whereby a smooth transition is obtained during the movement or lifting from road level to kerb level. This is achieved by the progressive transfer of the load from the climber unit wheel 26 to the front wheels as the latter mount the kerb 31. Thus, the front end of the wheelchair is not allowed to fall freely from a raised position.

In other words, the user of the wheelchair is not subjected to a sudden bump during the negotiation of a kerb which bumping could well be a very troublesome and dangerous occurance to some users of wheelchairs. In particular such users could well be those who rely on control systems which do not involve movements of hands and arms. That is the very seriously handicapped.

It will be appreciated that whilst a kerb climber unit involving a single wheel 26 has been discussed a double wheeled construction could be used in which construction the climber wheels would be co-axial. It should be noted that the siting of the climber unit wheels must be such that they do not impede the castor action of the front wheels 21.

As a further point of importance it will be noted that the climber unit wheel (or wheels) 26 do not extend forwardly of the footrest positions of the wheelchair. Amongst other things this ensures that the wheelchair user's legs and clothing can be kept away from possible engagement or entanglement with the climber unit wheel (or wheels) 26.

It is in the case of a double wheeled climber unit the wheels 26 may be located on the outside of the castored wheels. In such a case care must be taken to avoid limiting the castoring action of the front wheels 21. Because of this the provision of the external siting for the climber unit wheels 26 may lead to an unacceptable increase in overall width of a wheelchair.

Claims

1. An arrangementforenabling a wheeled unit or article such as a wheelchair to mount or climb an abrupt step or incline such as a kerb, the arrangement including a rotatable member, wheel, roller or like rotatable article which is arranged to be so positioned with respect to the remainder of the wheeled unit that the working surface thereof is able to engage with with and at least in part be able to negotiate the step in advance of the engagement of the leading wheels of the wheeled unit with said step, and wherein the leading wheels and said rotatable member, wheel, roller or like rotatable article overlap in the direction of advance of the wheel unit or article.

2. An arrangement as claimed in claim 1, wherein the rotatable member, wheel roller or like rotatable article has a radius of curvature greater than that of the leading wheels, and wherein the axis of rotation of the rotatable member, wheel, roller or like article is maintained out of contact with a surface upon which the leading wheels may be required to rest or travel.

3. An arrangement as claimed in claim 1 or 2, wherein when said leading wheels are mounted for castor action the axis of rotation of the rotatable member, wheel, roller or like article lies in a plane including the axes of castoring of the leading wheels.

4. An arrangement as claimed in anyone of claims 1,2 or 3, wherein means are provided for enabling the arrangement to be readily removably mounted to the wheeled unit or article.

5. An arrangement for enabling a wheelchairto mount or climb an abrupt step or incline such as a kerb, the arrangement including a rotatable wheel, roller or the like which is so positionable with respect to the wheelchair that the working surface of the rotatable wheel, roller or the like is able to engage with the kerb in advance of the leading wheels of the wheelchair, and wherein the leading wheels and said rotatable wheel, roller or the like overlap in the direction of advance of the wheelchair.

6. An arrangement as claimed in claim 5, wherein when the leading wheels of the wheelchair are mounted for a castoring action the axis of rotation of the rotatable wheel, roller or the like lies in a plane including the axis of castoring of the wheelchair leading wheels.

7. An arrangement as claimed in claim 5, wherein the rotatable wheel, roller or the like has a radius of curvature greater than that of the leading wheels whereby the rotatable wheel, roller or the like is maintained out of contact with any surface upon which the leading wheels rest or at any instant travel.

8. An arrangement as claimed in claim 5,6 or 7, wherein the overlapping of the leading wheels and said rotatable wheel, roller or the like is such that substantially the whole of the leading wheel on each side of the wheelchair is overlapped.

9. An arrangement as claimed in claim 5, 6,7 or 8, wherein the relative diameters of the rotatable wheel roller or the like and the leading wheels are such that the cusp formed by the overlapping of the working surfaces of the rotatable wheel, rollers or the like and the leading wheels is a shallow as possble.

10. An arrangement as claimed in any one of claims 5 to 8, wherein the axle or the like of the rotatable wheel, roller or the like is supported from a pair of support arms which are arranged for mounting from the side frames of the wheelchair.

11. An arrangement as claimed in claim 10, wherein the support arms are carried from a transverse main arm which is adapted for releasable connection to said side frames.

12. An arrangement as claimed in claim 11, wherein the transverse main arm is provided with two mounting and locating pins or the like each adapted for engagement with a location opening provided in the adjacent one of the side frames.

13. An arrangement as claimed in any one of claims 5 to 12, wherein the rotatable wheel, roller or the like is so positionable with respect to the wheelchairthatwhen mounted to the wheelchairthe rotatable member does not project in advance of the footrest mounting arrangements of the wheelchair.

14. An arrangementforenabling a wheeled unit or article as a wheelchair to mount or climb an abrupt step or incline such as a kerb, constructed and arranged to operate substantially as hereinbefore described with reference to Figures 3 to 9 of the accompanying drawings.