GB2026398A - Wheelchairs - Google Patents

Abstract

A wheelchair comprises a frame 10 with four wheels 15 and 18 and carries a seat 37, 39, the seat being movable by means of a parallelogram linkage 22, 24 so that as the seat is raised and lowered it is also moved forwardly and rearwardly. The arrangement facilitates entering and leaving a motor vehicle. The movement of the seat may be accomplished hydraulically. <IMAGE>

Description

SPECIFiCATION Wheelchairs This invention relates to wheelchairs for invalid use. The wheelchair is a four wheeled vehicle, usually having two swivellable wheels and two non-steerable wheels, the wheels being mounted on a frame carrying a seat.

When occupants of wheelchairs wish to use motor vehicles, the problem of loading and unloading have been solved in several ways.

One solution is to provide a specially designed vehicle with controls and a seat purposely designed for use by someone who normally uses a wheel chair. The wheelchair user, however, has to leave the wheelchair and transfer into the vehicle seat, the wheelchair itself being loaded, usually in folded condition, in the vehicle. The necessary manoeuvre are difficult to accomplish and often painful for the user. Furthermore it is not always possible to accomplish the transfer without help.

A further solution has been to adapt a vehicle to accept the wheelchair so that it takes up a position in which the occupant may control the vehicle without the necessity to leave the wheelchair.

Both these solutions require special adaptation of the vehicle or often a specially designed vehicle.

In my Patent Application No. 7900057 advantageous apparatus is described and claimed in which a wheelchair may be loaded and unloaded by its occupant into a motor vehicle in which modification of the vehicle from standard has been minimised. With this arrangement however a normal wheelchair cannot be used.

It is the object of this invention therefore to provide a wheelchair specially designed for use with this apparatus but which is also useful for normal wheelchair use, that is out of a motor vehicle as well as inside one.

According to the invention, there is provided a wheelchair comprising a frame carrying four wheels, and a seat mounted on the frame, the seat being adjustable with respect to the frame at least in a vertical direction.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a side elevation view of a wheel chair constructed in accordance with the invention; Figure 2 is a rear elevation view and Figure 3 is a fragmentary view showing some of the mechanism of the chair.

The chair has a frame of generally U shape made up from a pair of side plates 10, 11 and a floor 1 2. These are sheet metal and may include reinforcements (not shown) for stiffening in required positions.

At its rear end each side plate 10, 11 carries an axle 13, 1 4 four large rear wheels 1 5, 1 6 of the chair. These are shown in full in Fig. 2 but their outlines only are shown in Fig. 1.

At the forward end of the frame and carried on the respective plates 10 and 11 are swivel mounting 17, for swivellable front wheels 18, 1 9. As with the larger rear wheels 15, 1 6 these are shown in full in Fig. 2 but in outline in Fig. 1. Each such small front wheel is swivellable by means of a caster bracket indicated at 21 in Fig. 1.

Mounted on the base 1 2 of the frame are two pairs of links 22, 23, 24, 25. The links 22, 23 are pivoted on respective brackets 26 which enable pivoting of these links 22, 23, to take place about a common horizontal pivot axis 27. Similarly, the links 24, 25 are mounted on brackets 28 so that they pivot about a common horizontal pivot axis 29.

The two pairs of links are interconnected by a sub-frame 31 intermediate their ends. This sub-frame constrains the links 22 and 24 and the links 23 and 25 to move as two parallelogram linkages. At their upper ends the links 22, 23, 24, 25 are connected by respective brackets 32, 33 to a base 34 of a chair. As at their lower ends the links 22, 23, 24, 25 are pivoted about respective parallel horizontal axes 35 and 36. The chair base 34 carries a seat portion 37, these being connected by horizontal runners to allow the seat portion to move horizontally forward and back with respect to the chair base 34.

Pivotally connected to the seat portion 37 is a backrest portion 39 to which is slidably connected a headrest or head restrain 41.

Also pivotally connected to the seat portion 37 are two arm rests 42, 43. The pivotal connection is nearly coincident with the pivotal connection between the seat portion 37 and the backrest portion 39 and the dotted lines in Fig. 1 indicate how the arm rests 42 and 43 can be swivelled to a position to allow the occupant of the wheelchair to move off the seat portion sideways if desired.

Connected to fittings 44 at the front of the frame of the wheelchair are respective foldable and adjustable foot rests 45. The fittings 44 may also carry other attachments such as tables.

Particularly shown in Fig. 3 is hydraulic mechanism whereby the seat can be raised and lowered with respect to the frame of the wheelchair. The parallelogram linkage provided by the links 22, 23, 24, 25 and the subframe 31 between them causes the seat to move up and down as well as forward and back. This is indicated by the arrow 46 in Fig.

3. The hydraulic mechanism comprises two hydraulic piston and cylinder units 47, 48.

The larger of these units 47 has its piston pivotally connected to a horizontal bar of the subframe 31 so that it can pivot about an axis indicated at 49. The piston of the smaller of the units 48 is similarly pivotally connected to a rear horizontal bar of the sub-frame 31 to pivot about an axis 51 which is also horizontal and parallel to the axis 49. Both units 47 and 48 are pivotally connected at their cylinder ends to the frame floor 1 2 and are pivotal about a horizontal axis indicated at 52 in Fig.

3.

The hydraulic units are interconnected so that expulsion of fluid from one can flow into the other but since there is a substantial difference in capacity, due to the different sizes of the units, there must also be a reservoir (not illustrated) for accepting any additional fluid which cannot flow from the unit 47 into the unit 48 and for supplying additional fluid to the unit 47 when this is filling. Both units are single acting and appropriate valves are provided for controlling the directions of flow. The units 47 is capable of being filled from the unit 48 as well as from the reservoir under the action of a pump of which the handle is shown at 53. This handle carries a knob 54 conveniently placed for actuation by the occupant of the seat.The pump is arranged for multi-strolse operation to pump up the unit 47 and thus push the seat from a lowered position to the raised position which is shown in full lines in the drawings.

There is also a further lever 55 having a knob 56 which actuates a valve for permitting exhaust of the cylinders. The cylinder unit 48 contains a restrictor valve which regulates the rate of lowering of the seat under the weight of the occupant. This valve may be adjustable so as to provide different lowering rates or to provide a constant lowering rate with different weights of occupant.

Preferably, the hydraulic cylinders and associated valves are housed within a common unit to eliminate external hydraulic connections which may involve vulnerable flexible pipes.

To the side plates 10, 11 of the frame are secured respective brakes one of which is shown at 57 in Fig. 1. These are of conventional kind and actuate directly upon the tyre of the large rear wheel of the wheelchair.

At the rear of the frame is mounted an auxiliary wheel unit. This comprises either one or a pair of small wheels 58. A pair of such wheels is shown in Fig. 2. These are arranged to be driven through an electric motor 59 powered by a battery 61 mounted on the floor 12 of the frame. As shown in Fig. 1, the auxiliary wheel unit can occupy a raised position and a lowered position in which it is in contact with the ground. Movement from one position to the other is accomplished by the movement of the seat. As the occupant lowers the seat under the hydraulic control already explained, the underneath of the seat portion 37 contacts the auxiliary wheel unit. Continued lowering causes the wheel to be brought down to the lowered ground contacting position. In this position, therefore, actuation of the electric motor will rotate the auxiliary wheel or wheels 58 to drive the wheelchair.

This wheelchair has particular, though not exclusive application in relation to apparatus described and claimed in Patent Application 7900057. The raising and lowering of the seat is convenient for loading and unloading into the vehicle and for bringing the occupant of the wheelchair into a suitable position for driving of the vehicle. The auxiliary wheel drive is furthermore useful for assisting the loading of the wheelchair into the vehicle. The auxiliary wheel drive mechanism is the subject of my Patent Application No. 7913266. The forward and back adjustment provision of the seat is the subject of my Patent Application 7913265.

Claims (5)

1. A wheelchair comprising a frame carrying four wheels, and a seat mounted on the frame, the seat being adjustable with respect to the frame at least in a vertical direction.

2. A wheelchair as claimed in claim 1 in which the chair is mounted on a parallelogram linkage connected to the frame, this linkage being arranged to move the chair relatively to the frame with simultaneous vertical and horizontal components of movement.

3. A wheelchair as claimed in claim 1 or claim 2 in which the seat is adjustable relatively to the frame by a fluid pressure actuated mechanism.

4. A wheelchair as claimed in claim 3 in which the fluid pressure actuating mechanism includes a pump for raising the seat and a flow restricting device for permittting controlled lowering of the seat.

5. A wheel chair substantially as herein be fore described with reference to and as shown in the accompanying drawings.