GB2136742A - Wheelchairs - Google Patents

Abstract

A wheelchair comprises a generally rectangular box-like frame supported on at least three wheels (90), a seat (330) supported in the frame, and a backrest (320) for the seat. The backrest (320) is movable in one direction from a generally upright position to a folded position overlying the seat, and, in the opposite direction, to a reclining position. Movement of the backrest to the reclining position (320A) is accompanied by a corresponding movement of the seat from a rearward position (330) to a forward position (330A) to avoid movement of the centre of gravity of an occupant. <IMAGE>

Description

SPECIFICATION Wheelchairs This invention relates to wheelchairs for handicapped people and, in particular, to the transfer of such wheelchairs into motor vehicles.

Transferring a handicapped person from a wheelchair into a seat of a motor vehicle is frequently a painful and hazardous operation. Vehicles such as vans, small buses, and ambulances are therefore sometimes equipped with tail-lift mechanisms which enable wheelchairs to be lifted and driven into the back of the vehicle. But such mechanisms are cumbersome and unsuited for use in a normal family-sized car.

In one previous proposal for transferring a wheelchair into a family car, a revolving platform is fitted in the car in place of the normal seat. In use, a ramp is extended from the platform into the kerb or road, and the wheelchair is manoeuvred up the ramp onto the platform. The platform is then revolved to bring the wheelchair to its front-facing position. The mechanism requires a wheelchair which can be adjusted to reduce its height for positioning in the car. Once inside the car, the wheelchair is locked in position and is intended to be used as a driving seat if required.

An advantage of this prior proposal is that the wheelchair occupant can enter or leave the car without having to get out of the wheelchair. On the other hand the mechanism is complicated and, with the variation in seating layout and size of doorways, it is unlikely that the unit could be fitted in a wide range of cars unless it were separately designed for each car model. Moreover, since the ramp angle would be steep when entry was from the road rather than from a kerb, the mechanism would need to be powered externally for many wheelchair occupants who would lack the strength to push themselves up the ramp.

In my co-pending Application 80 04920 1 claim a method of transferring a wheelchair through a side door opening into a motor vehicle, the method comprising: reversing the chair up to the door opening, linking the chair to a hoisting mechanism, hoisting the chair off the ground, and swivelling the said linkage about at least one generally vertical axis fixed in the vehicle, the linkage being so arranged that, when swivelling about the said axis or axes, it follows a predetermined path while moving from an extended position to a retracted position relative to the side door opening. The suspended chair is preferably then pivoted about its point of suspension to complete the lateral movement of the chair into the vehicle and to bring the chair to a front-facing position.

In accordance with the present invention I provide a wheelchair comprising a generally rectangular box-like frame supported on at least three wheels, a seat supported in the frame, and a backrest for the seat, the backrest being movable between at least one generally upright position and a folded position lying within the said frame.

The seat is preferably movable between a forward position and a rearward position, and the backrest is further movable in the opposite direction from its upright position to a reclining position, the arrangement being such that movement of the backrest from its upright position to its reclining position is accompanied by a corresponding movement of the seat from its rearward position to its forward position. This maintains the occupant's centre of gravity in approximately the same position and thereby retains the stability of the chair.

The wheels of the chair are preferably retractable with respect to the frame when the chair is lifted off the ground, and this further assists transfer of the chair into a motor vehicle.

By way of example only, an embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure lisa side view of a motor car showing a wheelchair ready for transfer into the car, Figure 2 is a diagrammatic side view of the wheelchair and the transfer mechanism, Figure 3 is a perspective view of the wheelchair and transfer mechanism, and Figure 4 is a plan view of the wheelchair and transfer mechanism.

Figure 5 is a side view of the wheelchair folded into a 'shopping trolley' configuration, Figure 6 is a side view of a self-propelled wheelchair embodying the invention, Figure 7 is a front view of a portion of the chair shown in Figure 6 and showing the rear suspension, Figure 8 is a plan view of the portion of the chair shown in Figure 7, and Figure 9 is a side view of the chair of Figure 6 shown in its folded configuration.

As illustrated in Figures 1 to 4, the transfer mechanism includes a lifting device and a swivel linkage. The wheelchair is constructed so that it has sufficient strength to be lifted, complete with the occupant, from either flat ground or kerbing, by the lifting device which is fixed in the car. The lifting device and linkage lift and transfer the wheelchair, complete with its occupant, through the doorway of any small car or van, and then lower and lock the wheelchair into the normal seating position, and vice versa.

The lifting device includes a vertical, squaresection tube 10 fixed to the floor 11 and to the top rail 12 of the car. The tube 10 is located just to the rear of the proposed seat position but alternatively, may lie adjacent the front door post.

Slidably mounted on the tube 10 is a second tube 13 which is slightly larger than the tube 10 and slides up and down on roller bearings. The outer tube 13 carries the linkage mechanism, and is operated by mechanical, electrical, hydraulic, or pneumatic jack means 14.

If a hydraulic or pneumatic jack is used for lifting the outer tube 13, initial actuation of the jack lowers a stabilising foot 15 between the floor of the car and the ground so that any sag of the car suspension when lifting the chair is eliminated.

The linkage mechanism consists of two vertical plates 16 and 17 hinged on both vertical edges. The rear, or inner, edges are pivoted on plates 18 and 19 secured to the outer tube 13, and the front, or outer, edges are pivoted onto a transfer plate 20 carrying two vertical tapered pins 21,22 which locate in bearings 23 and 24 secured to the rear of the wheelchair 25.

In operation, the wheelchair is reversed up to the open doorway of the car. With the outer tube 13 in its lowered position and the linkage arms 16,17 in their extended position as shown in Figure 4, the chair is aligned so that, when the outer tube 13 is raised, the conical pins 21,22 locate in the bearings 23, 24 at a rear corner of the chair frame. Further operation of the lifting device then lifts the chair off the ground and, as soon as it is high enough, the wheels 26,27 and 28 are retracted into the frame (as shown in Figure 3), the chair is then free to be transferred to the car.

The vertical plates 16, 17 are then swung through a small arc to their retracted position shown in dashed outline in Figure 4, and this swings the chair part-way into the vehicle while keeping it clear of the front door post. The chair can then be rotated about the vertically aligned pivots 21, 22 to face the front of the vehicle. Since the chair is suspended at a rear corner of its frame, this final pivoting of the chair simultaneously transfers the chair sideways by a distance almost equal to the full width of the chair and thereby completes its sideways movement into the vehicle.

The chair is then lowered until it rests on a frame secured to the floor of the car, and it is releasably locked in this position by any convenient locking mechanism. The whole transfer process, if required, can be powered.

The method of transfer requires a very strong wheelchair. To achieve this, the structure of the chair may be a metal or fiberglass monocoque with a box-like tubular sub-frame.

Thefourwheels 26,27,28 and 32 are retracted into the frame alongside the seat 29 of the wheelchair and into the respective hollow arms 30 and 31. This reduces the overall height of the chair and so allows it to be transferred with its occupant through the average side door opening of a car.

The wheelchair does not fold in the normal way (sides together) but is constructed so that the back folds forward. This, together with the retractable wheels, enables folding of the chair to a compact size considerably smaller than that achieved by normal collapsible chairs. By locking the wheels in a partially extended position, and pulling out a built-in handle, it adopts a 'shopping trolley' configuration as shown in Figure 5 which enables it to be pushed along easily.

The wheelchair may be attendant, self or electrically propelled. In the self-propelled model, a 'capstan' wheel is provided which can be of varying sizes but will be situated alongside the occupant and will be connected to the road wheels via a chain or belt.

The capstan wheel 32 is illustrated diagrammatically in Figure 2. The capstan wheel is easily changeable allowing for the provision of varying surface textures and/or shapes, and varying gear ratios for differing disabilities and strengths of the wheelchair occupant. Not only does this enable the disabled person to choose a wheel particularly suitable for his handicap but, because the capstan wheel is well away from the road wheels, it is in all cases cleaner for hands and clothing than the usual method of self-propulsion (another handwheel of slightly smaller diameter and just outside the road wheel).

The back of the wheelchair may be lowered to a reclining position as shown by the dashed outline in Figure 2 while retaining its stability. Stability is maintained because the seat portion moves forward as the back lowers to the reclining position, so keeping the centre of gravity in approximately the same place i.e. within a short wheel base, and thus providing the advantages of a recliner without the usual disadvantage of loss of manoeuvrability due to a long wheelbase.

The wheelchair also has an ergomically designed seat made possibie by the front-to-back method of folding.

The chair is also provided with desk arms which may be extended to the desired full arm-rest length, and which can be flipped over for easy side exiting.

The chair has flat surfaces which easily accept reflective discs for night safety.

In general, the described chair is far stronger and safer than collapsible wheelchairs at present available. The described transfer process enables the seat to be swung into a position behind the steering wheel of a car. Unlike the previously described proposal using a ramp and revolving platform, this can be done without requiring any modification to the steering wheel, With reference now to the self-propelled wheelchair shown in Figures 6 to 9, the wheelchair is provided with a 'capstan' 100. The capstan is shown with a smooth latex rim but this can have any contour or texture; it is located on a square drivepeg 110 and retained by a clip 120. The drive-pegs are connected to the rear road wheels via a chain or toothed belt 130.

The rear wheels 90 are mounted on swing-arms 140 that are split and spigotted 150 to allow independent action and which run in bearings 160, with a brake-rod 170 running down a hollow axis tube.

Connected to the swing-arms 140 are links 180 with rollers at the opposite ends, which in turn are connected to links 190 that have a safety catch 200 which enters and leaves its guide only when the chair is off the ground so preventing premature folding. Link 190 acts on rubber suspension medium 210 under the control of arm 220. A rod 230 connects left-hand and right-hand suspensions and so has to have an angular joint 240 because of the independent action of both rear wheels 90.

Solidly fixed to rod 230 is lever 250 which operates the folding mechanism for the rear-wheels. The 'capstan' 100 may be easily removed to assist side exit and for folding, hence the quick-release catch 120. The front castors 260 retract by simply rotating in either direction about axis 270. When the chair is folded into its shopping trolley configuration (Figure 9) the rear wheels can be set down to position 280 allowing the unit to be pulled along by extending handle 290 which also acts as the adjustment for the foot-rest 300.

The rigid, contoured back-rest 320 can recline 320A or fold forward 320B. When reclining, the action of the back-rest moves the seat squab 330 forward 330A to maintain the occupant's centre of gravity in approximately the same place and so retain stability: this action can, if required, also elevate footrests 300 by means of a pin 400. When folding, the action of the back-rest moves the seat squab back and down to position 330B to provide a compact shape and to allow for the footrests 300 to be swung over and be contained in the hollow between the seat back 320B and seat squab 330B.

The position of the squab is controlled by the links 340and350.

For folding and when the seat is fixed in a motor vehicle, the handles 360 fold down (a safety measure); an alternative handle 370 is shown which has greater height adjustment and would allow the occupant to be pushed whilst in the semi-reclining position. Arms 380 can be flipped over for easy side exit and adjusted for length and angle. Also shown is a control lever 390 for an eiectric chair; Figure 9 shows, in dotted lines, the positions of two dry-cell batteries 410.

Claims (1)

1. A wheelchair comprising a generally rectangular box-like frame supported on at least three wheels, a seat supported in the frame, and a backrest for the seat, the backrest being movable between at least one generally upright position and a folded position lying within the said frame.

2. A wheelchair according to Claim 1 in which the seat is movable between a forward position and a rearward position and the backrest is further movable in the opposite direction from its upright position to a reclining position, the arrangement being such that movement of the backrest from its upright position to its reclining position is accompanied by a corresponding movement of the seat from its rearward position to its forward position.

3. Awheelchair according to Claim 1 or Claim 2 in which the wheels are retractable with respect to the frame when the wheelchair is lifted off the ground.

New claims or amendments to claims filed on 3.2.84 Superseded claims 1 and 2 New or amended claims:

1. A wheelchair comprising a generally rectangular box-like frame supported on at least three wheels, a seat supported in the frame for movement between a forward position and a rearward position, and a backrest for the seat, the backrest being movable in one direction from a generally upright position to a folded position overlying the seat and in the opposite direction from its upright position to a reclining position, the arrangement being such that movement of the backrest from its upright position to its reclining position is accompanied by a corresponding generally horizontal movement of the seat from its rearward position to its forward position whereby the centre of gravity of an occupant seated in the chair remains in approximately the same position relative to the chair frame.