GB2124557A - Wheelchairs - Google Patents

Abstract

A wheelchair is in two parts, viz. an L-shaped frame (10) and L-shaped seat (11). The frame (10) and seat (11) can move vertically one relative to the other by means of a height- adjustment mechanism formed of a screw spindle (14) on which a tapped block (19) is threadedly engaged, the spindle (14) being secured to the frame (10) and the block (19) connected to the seat (11). A motor (18) rotates the spindle (14) to raise or lower the seat (11) relative to the frame (10). The seating portion (11A) of the seat is dimensioned to move between the limbs of the U-shaped bottom member (10B). <IMAGE>

Description

SPECIFICATION Wheelchairs This invention relates to wheelchairs which are for use by persons who are permanentiy or temporarily disabled as a conveyance to allow them to move about inside or outside of a building.

Wheelchairs have been provided heretofore of the type comprising a frame having a seat with a seating portion and a back rest portion. The frame has four wheels, two large-diametered rear wheels and two castor front wheels, and can be self-propelled by manual rotation of said largediametered wheels using two circular rails secured on the outside one of each of said two wheels.

Two arm rests and two foot rests are provided, together with two handle grips rearward of the seat and for use by a third party to propel a wheelchair. Brakes are aiso provided. Persons using wheelchairs are generally of an independant nature, that is they prefer to be able to accomplish various tasks without any reliance on a third party.

A disadvantage of existing wheelchairs is that the seat is rigidly mounted on the frame and the seating portion is provided at a standard height, suitable for sitting at a table but not suitable for working at, for example, unadapted high level kitchen work tops, or other work benches or tables or cookers.

An object of the present invention is to obviate or mitigate this disadvantage.

According to the present invention, there is provided a wheelchair comprising a frame and a seat slidably interconnected and height adjustable relative to each other through an adjustable height mechanism, and power means to drive said mechanism with controls to operate said power means.

Preferably, the frame has a horizontallyoriented bottom member to which the wheels are mounted, the bottom member being U-shaped in plan with the open end at the front of the wheelchair, and a seating portion of the seat is dimensioned smaller than the area defined by the parts of said bottom member thereby enabling the seating portion to be lowered relative to the frame to a horizontal level below said bottom member.

Preferably also, two footrests are provided carried by pertaining longitudinals of a support framework of the seating portion, each footrest comprising a bar or rod supporting at its lower end a footplate, the bar or rod being movable between an in-use downwardly inclined position and an out-of-use position stowed inside the pertaining longitudinals, with the foot plates being capable of movement relative to their pertaining bars or rods such that they can be moved to a position which will not interfere with a users movements.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevational view of an unupholstered wheelchair according to the present invention; Fig. 2 is a rear view of the wheelchair; and Fig. 3 is a plan view of the wheelchair.

Referring to the drawings, a wheelchair comprises a frame 10 and a seat 11. The frame 10 has in side elevation an upright back member 1 0A normally of a substantially horizontal bottom member 1 OB. The back member 1 OA is rectangular and the bottom member 1 OB is Ushaped in plan and with the open end facing forwardly of the chair. The seat 11 has a framework angled in side elevation and defining a horizontal rectangular seating portion 11 A and an elongate rearwardly-raked back-rest portion 11 B braced together as shown by webs 12, one on each lateral side of the seat. A head rest (not shown) is provided above the back-rest portion 11 B and a mounting 13 for said head rest is shown.The seating portion 11 A is dimensioned to be less than the area defined by the web and limbs of the U-shaped bottom member 1 OB of the frame 10 to enable the seating portion 11 A to be capable of passing between said web and limbs.

The frame 10 and seat 11 are slidably interconnected and are height-adjustable through an adjustable-height mechanism comprising an upstanding screw spindle 14 held in top and bottom bearings 1 5 on cross-braces 16 of the back member 1 OA of the frame 10 and secured at its bottom end below said bottom bearing 1 5 to a coupling 17 attached to an output of power means in the form of an electric motor 1 8. ON/OFF controls are provided for the motor. The motor 1 8 can be energised by a rechargeable battery (not shown) carried by the frame 10 adjacent to said motor 1 8 or provided separately therefrom.A tapped block 1 9 is screw-threadedly engaged on said spindle 14 and connected to the seat 11 behind its backrest portion 11 B so that rotation or counter-rotation of the spindle 14 causes upwards or downwards movement of the seat 11 or if the seat 11 is held stationary, upwards or downwards movement of the frame 1 0.

Two vertically-shaped roller mountings 20 are provided extending rearwardly of the backrest portion 11 B of the seat 11 and run along pertaining verticals 21 of the upright back member 1 OA of the frame 10. The mountings 20 each have two rollers 20A and 20B. Roller 20A is a flat faced roller whose surface bears against one face of the pertaining vertical 21 and roller 20B is a spool roller whose recessed surface runs on the opposite face of the pertaining vertical 21 with the projecting rims overlapping the lateral sides of said pertaining vertical 21. The disposition of rollers 20A, 20B is reversed in each mounting 20 i.e. in the lower mounting 20 the roller 20A is adjacent to the backrest portion 11 B of the seat and is remote therefrom in the upper mounting.

The mountings 20 are arranged to be above and below the disposition of the block 1 9.

Two footrests are provided carried by pertaining tubular longitudinals 22 of the framework of the seating portion 11 A. Each footrest comprises a bar or rod slidable 23 in a bearing secured in the end of each said longitudinal 22 and each bar or rod 23 is in two parts jointed by a tenon-joint adjacent to the longitudinals 22 when the bars 23 are fully-extended. Each bar or rod 23 supports at its lower end a footplate (not shown).

The bar or rod 23 is movable between an in-use fully extended, downwardly-inclined position, and an out-of-use position fully-stowed inside the pertaining longitudinals 22 with the footplates being capable of movement relative to their pertaining bars or rods 23 such that they can be swung out of the way.

The bottom member 1 OB mounts the four conventional wheels namely two large-diametered wheels 24 with rails 25 and two castors 26, and a braking mechanism 27 is provided, as conventionally, for each of the two large diametered rear wheels 24. Mud guards 28 are provided as shown for each wheel 24.

Armrests 29 (Fig. 1) one for each lateral side of the seating portion 1 1A are provided hinged upright of back-rest portion 11 B and which can be swung upwardly out-of-the-way. The back-rest portion 11 B seating portion 11 A and webs 12 are upholstered, use being made of the wire anchorages 32 shown on the seating portion 11 A.

To prevent over-run i.e. movement of the seat above and below determined limits, limit switches 33 (Fig. 2) are connected at the appropriate positions as the screw spindle 14 or on a rod 34 provided parallel thereto and offset therefrom towards one vertical 21. The limit switches 33 are operable by a magnetic switch 35 mounted on the connection 36 for the block 19.

A wheelchair above-described is moved in a conventional manner either by the user selfpropelling the chair as above-described or by the chair being pushed by a third party using a handle 30 provided, and foot bars 31 provided to pivot the chair about the axes of wheels 24 to mount, for example a viser such as a pavement. The person using the wheelchair can as required operate the controls of the motor to increase or decrease the height of the seat 11 relative to the frame 10.

Claims (11)

1. A wheelchair comprising a frame and a seat slidably interconnected and height adjustable relative to each other through an adjustable height mechanism, and power means to drive said mechanism with controls to operate said power means.

2. Wheelchair as claimed in Claim 1, wherein the frame has a horizontally-oriented bottom member to which the wheels are mounted, the bottom member being U-shaped in plan with the open end at the front of the wheelchair, and a seating portion of the seat is dimensioned smaller than the area defined by the parts of said bottom member thereby enabling the seating portion to be lowered relative to the frame to a horizontal level below said bottom member.

3. Wheelchair as claimed in Claim 2, wherein the adjustable height mechanism comprises a screw-threaded spindle mounted uprightiy for rotation on a back member of the frame and on which a tapped block is threadedly engaged, the block being connected to the rear of a backrest portion of the seat in which connection the block is prevented for rotational movement, the spindle being connected to the power means.

4. Wheelchair as claimed in Claim 3, wherein a rod is mounted parallel with the spindle with upper and lower limit switches carried thereon, each activated in turn by the seat progressing up or down beyond determined limits on the spindle.

5. Wheelchair as claimed in any one of the preceding claims, wherein two vertically-spaced rollers mountings are provided extending rearwardly at each side of the backrest portion of the seat to track pertaining verticals of the upright back member of the frame.

6. Wheelchair as claimed in Claim 5, wherein the mountings lie in higher and lower horizontal lanes relative to the plane in which the block lies.

7. Wheelchair as claimed in Claim 5 or 6, wherein in each mounting, two spaced rollers are carried whose peripheries track opposite sides of the pertaining vertical.

8. Wheelchair as claimed in Claim 7, wherein one of said rollers in each mounting is a spool roller whose rims overlap the lateral sides of said pertaining vertical.

9. Wheelchair as claimed in Claim 8, wherein the disposition of the rollers is reversed between the upper and lower mountings.

1 0. Wheelchair as claimed in any one of the preceding claims, wherein two footrests are provided carried by pertaining longitudinals of a support framework of the seating portion, each footrest comprising a bar or rod supporting at its lower end a footplate, the bar or rod being movable between an in-use downwardly inclined position and an out-of-use position stowed inside the pertaining longitudinals, with the foot plates being capable of movement relative to their pertaining bars or rods such that they can be moved to a position which will not interfere with a users movements.

11. Wheelchairs substantially as hereinbefore described with reference to the accompanying drawings.