GB2203332A - Demountable wheelchair - Google Patents

Abstract

An improved demountable wheelchair comprising a chair frame assembly for supporting a wheelchair patient thereon, a base frame assembly supported by wheels, and intermediate chair sub-frame including spring suspension means, interconnecting the said frame assemblies whereby the chair frame assembly is suspended for movement relative to said base frame assembly, and pivot means pivotally interconnecting said chair sub-frame and said chair frame assembly whereby said chair frame assembly is able to undergo tilting movement about a transverse horizontal axis, and securing means removably attaching the intermediate chair sub-frame means to said base frame assembly. <IMAGE>

Description

A D-;};OR r,3 This invention relates to improvements in wheelchairs, and in particular to a wheelchair which is of demountable construction.

Many different types of wheelchair constructions have been developed over the years with features which are mainly intended to make life easier for a wheelchair patient, particularly in those cases where the patient is unable to make full use of his or her arms and/or legs, and it seems that very little attention has been given to the sitting comfort of the patient when moving around in the wheelchair or when it is stationary. In particular, although wheelchairs are normally well cushioned to support a patient, the applicant is unaware of any attempt to design a wheelchair wherein the chair frame is supported by a suspension for the purpose of improving the "ride" of the patient when the wheelchair is mobile.

Another disadvantage with known wheelchair designs is their inability to be dissassembled readily and simply - as is required when transporting the wheelchair in a vehicle for example.

It is the main object of the present invention to provide an improved wheelchair wherein the chair frame is supported by a suspension, which is of very simple construction and is inexpensive to manufacture.

It is a further object of the present invention to provide an improved wheelchair incorporating a spring suspension which can be readily disassembled for ease of transport.

It is a still further object of the present invention to provide an improved wheelchair which contains few moving parts (in comparison to known wheelchair constructions) and which is of sturdy construction.

According to this invention therefore, an improved wheelchair comprises a chair frame assembly for supporting a wheelchair patient thereon, a base frame assembly supported by wheels, an intermediate chair sub-frame means including spring suspension means, interconnecting the said frame assemblies whereby the chair frame assembly is suspended for movement relative to said base frame assembly, and pivot means pivotally interconnecting said intermediate sub-frame means and said chair frame assembly, and securing means removably attaching the intermediate sub-frame means to said base frame assembly.

In a preferred embodiment, said spring suspension means comprises a pair of transversely aligned vertically (or nearly so) disposed coil spring means, each of which comprises a coil spring and a spring guide bolt extending axially therethrough, said bolt being removably connected to the chair frame and the intermediate support frame.

Preferably, each of the springs has its ends abuttingly engaging against the underside of a chair frame member and an upper surface of an intermediate support frame member.

Preferably, the chair frame is pivotally connected near its forward end to the intermediate support frame and the springs are spaced rearwardly from the pivot connection.

Preferably, the base frame assembly comprises a pair of parallel transversely spaced longitudinally extending frame members, cross frame members interconnecting said longitudinal frame members, a pair of large wheels supporting the rear end of said base frame assembly and a pair of relatively small castor type wheels supporting the forward end of said base frame assembly, said small wheels being arranged for steering of the wheelchair. Preferably, each said large wheel has operatively associated therewith a manually operated braking mechanism for individually braking said wheels.

In another preferred form of this invention, said chair frame assembly comprises a horizontally disposed cushion support frame which supports a cushion on which a patient sits, a tiltable back support frame of inverted U-shape, pivot means pivotally attaching said back support frame to said cushion support frame for tilting movement about a transverse horizontal axis, a leg support frame extending forwardly and downwardly from said cushion support frame and pivotably attached thereto whereby the inclination of the leg support frame is adjustable, and upstanding arm rests, one on each side of said cushion support frame and removably secured thereto. In yet another preferred arrangement, said leg support frame comprises a pair of spring mounted foot rest members, each of which is mounted for inward swinging movement in the event of it striking an obstacle as the chair is moved along.Each of the footrests is also mounted for pivotal movement about a substantially longitudinal axis which is inclined to the horizontal, whereby the foot rests may be swung upwardly to approximately vertical positions for transporting purposes.

In order to more fully explain the applicant's invention an embodiment is described hereunder in some further detail, with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of a wheelchair according to this invention, FIG. 2 is an "exploded" perspective view of the chair shown in FIG. 1, FIG. 3 is a side elevational view of the chair in a "lay-back" position, and FIG. 4 is a fragmentary (partly cut-away) perspective view of the foot rest member detachably connected to the lower end of the chair frame.

In this embodiment, a wheelchair 10 is provided with a seat or chair frame assembly 11 arranged to support a patient thereon, a base frame assembly 12, and an intermediate chair sub-frame 13 including a spring suspension, the sub-frame 13 interconnecting the frame assemblies 11, 12 and being arranged to resiliently support the seat frame assembly 11 above the base frame assembly 12 for relative movement therebetween. The base frame assembly 12 is itself supported by two pairs of rubber tyred wheels, one pair comprising two large electrically driven wheels 15 which support the rear end of the base frame 12, the other pair comprising two relatively small wheels 16 which are castor wheels arranged for steering the wheelchair and support the forward end of the base frame assembly 12.

The base frame assembly 12 in this embodiment comprises a pair of transversely spaced parallel longitudinally extending base frame members 17 interconnected by a plurality of cross-frame members 18, the frame members all being of square metal tubing.

The forward ends of the longitudinal frame members 17 are provided with vertical short length sleeves 21 which locate the upstanding posts or stems of the castor wheels 16, to thereby enable such wheels 16 to freely pivot.

Each of the wheels 15 has associated therewith a manually operated friction braking mechanism 22 for individual braking thereof. The base frame assembly 12 is further provided with additional short length frame members 23 extending below the frame members 15, which carry bearings (not shown) in which are journalled the stub axles 24 carrying the large wheels 15. In this embodiment, the base frame 12 is provided with a known electrical power source and drive system for driving the wheels 15 and controlled by means of an adjustable joy stick 25 located on the chair frame 11.

The chair or seat frame assembly 11 comprises a rectangular cushion or seat support frame 26 which supports a rectangular cushion 27 on which the patient can sit, a reclinable back support frame 30 pivotally attached to the rear end of the seat support frame 26, and a forwardly and downwardly extending leg support frame 31 which is pivotally attached to the forward end of the seat support frame 26 whereby the angle of the leg support frame 31 with respect to the substantially horizontal seat support frame 26 can be readily varied.

In this embodiment the leg support frame 31 is formed of square metal tubing and comprises a pair of transversely aligned downwardly extending side members 32 each of which is pivotally attached at its upper end to the forward end of a respective seat frame member 33, the lower ends of the members 32 having secured thereto, for example by welding, short length rectangular-section angle mounting sleeves 35 which are arranged to pivotally support a pair of foot rests 36, each foot rest 36 comprising a peripheral frame member 37 of tubular metal which is supported on its outer side by a short length support arm 38 which in turn is located within a respective sleeve 35 and pivotally received therein to enable the foot rest 36 to swing inwardly in the event of the foot rest 36 striking an obstacle when the wheelchair 10 is mobile.Each foot rest 36 is spring-loaded by means of a U-shaped blade spring 40 located interiorly of the sleeve 35 and arranged so that the bias of the spring urges the foot rest 36 to its normal at rest position. The leg support frame 31 is further provided with a pair of cushioned support pads 41 so as to provide comfortable support for a patient's legs when the leg support frame 31 is in an extended position.

The cushioned pads 41 are preferably removably secured to the support frame members 32.

The back support frame 30 is of inverted U-shape and formed of metal tubing, there being a cushioned panel 42 extending between the sides 43 of the frame 30 so as to provide comfortable support for the patient's back.

The back support frame 30 is able to be tilted to a position where it is in approximate horizontal alignment with the seat support frame 26, this being desirable when the wheelchair is required to be transported and can thus be folded to an essentially flat condition.

In accordance with normal design, the chair frame assembly 11 is also provided with a pair of upstanding arm rests 44, one on each side of the seat support frame 26, each arm rest 44 comprising an angle support arm 46 detachably secured to a seat support frame member 33, there being a padded cushion 47 attached to each arm 46. Each arm 46 is provided with an inturned spigot member at its lower end which slidably engages in a socket tube 48 carried on the underside of the seat support frame 26, the spigot socket connections enabling the arm rests 44 to be readily disassembled.

The spring suspension comprises a pair of transversely aligned approximately vertically disposed coil springs 49, each of which has its upper end abutting against the underside surface of a respective seat frame member 33 of the seat support frame 26, and its lower end abutting against the upper face of bent frame member 50 of the intermediate chair sub-frame 13. Each coil spring 49 has a locating bolt 51 projecting through a hole in the frame member 50 and threadably engaging a tapped hole in the frame member 33. This enables the springs 49 to be readily dismantled if required.

The intermediate sub-frame 13 is detachably connected to the base frame 12 and comprises a pair of longitudinally extending, transversely spaced frame members 53 which engage on top of corresponding longitudinal frame members 17 of the base frame 12 and front and rear cross members 55, 55' interconnecting the members 53.The sub-frame 13 is restrained against movement in one longitudinal direction as well as vertical displacement relative to the base frame 12 by means of two pairs of aligned approximately inverted L-shaped abutment pins 56 on the base frame and against which the cross-frame members 55, 55' of the sub-frame 13 abut when the sub-frame 13 is located on the base frame 12, and against movement in the opposite longitudinal direction by means of a pivoted locking lever 57 which has a clamp plate 59 which lockingly engages against the front face of cross-frame member 18 of the base frame 12.

The pins 56 also restrain the sub-frame 13 against lateral movement relative to the base frame 12.

The chair frame 11 is pivoted near its forward end to inclined frame members 60 of the sub-frame 13 by means of transverse pivot bolts 61, to thereby enable the chair to undergo limited tilt movement whilst being cushioned by the springs 33.

An advantage of the design construction of the wheelchair according to the present invention is the manner in which the wheelchair is able to be readily disassembled for transport whereby it can be easily stowed in the trunk of a vehicle. Furthermore, by removing the chair frame together with its sub-frame from the base frame, it can then be fitted to a conventional non-powerised base frame which thus avoids the need to have to transport heavy electrically powered base frames.

A brief consideration of the above embodiment will indicate that the invention provides a wheelchair construction which is extremely simple, of low cost, and which because of its spring suspension provides vastly improved sitting comfort for the patient particularly during use thereof, and enables the patient to carry out limited but useful body "exercise" by rocking the chair frame.

Claims (13)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An improved demountable wheelchair comprising a chair frame assembly for supporting a wheelchair patient thereon, a base frame assembly supported by wheels, and intermediate chair sub-frame including spring suspension means, interconnecting the said frame assemblies whereby the chair frame assembly is suspended for movement relative to said base frame assembly, and pivot means pivotally interconnecting said chair sub-frame and said chair frame assembly whereby said chair frame assembly is able to undergo tilting movement about a transverse horizontal axis, and securing means removably attaching the intermediate chair sub-frame means to said base frame assembly.

2. An improved wheelchair according to claim 1 wherein said spring suspension means comprises a pair of transversely aligned vertically disposed coil springs, each said coil spring having its upper end abutting against the underside of a respective chair frame member of said chair frame assembly, and its lower end abutting against a respective said frame member of said intermediate chair sub-frame means.

3. An improved wheelchair according to claim 2 wherein each said coil spring is provided with a spring guide bolt extending axially therethrough, said guide bolt extending between respective frame members of said chair frame assembly and said chair sub-frame.

4. An improved wheelchair according to either claim 2 or claim 3 wherein said pivot means comprises a pair of transversely aligned horizontal pivot bolts located near the forward end of said chair frame assembly, said pair of coil springs being spaced rearwardly from said pivot bolt.

5. An improved wheelchair according to any preceding claim wherein the base frame assembly comprises a pair of parallel transversely spaced longitudinally extending frame members, cross-frame members interconnecting said longitudinal frame members, a pair of large wheels supporting the rear end of said base frame assembly and a pair of relatively small castor type wheels supporting the forward end of said base frame assembly, said small wheels being arranged for steering of the wheelchair.

6. An improved wheelchair according to claim 5 wherein each said large wheel has operatively associated therewith a manually operable braking mechanism for individually braking said wheels.

7. An improved wheelchair according to any preceding claim wherein said chair frame assembly further comprises a horizontally disposed cushion support frame for supporting a cushion on which a patient sits, a tiltable back support frame of inverted U-shape, pivot means pivotally attaching said back support frame to said cushion support frame for tilting movement about a transverse horizontal axis, a leg support frame extending forwardly and downwardly from said cushion support frame and pivotally attached thereto whereby the inclination of the leg support frame can be adjusted, and upstanding arm rests, one on each side of said cushion support frame and removably secured thereto.

8. An improved wheelchair according to claim 7 wherein said leg support frame comprises a pair of spring mounted foot rest members, each being mounted for inward swinging movement whereby, in the event of a foot rest member striking an obstacle during forward movement of the wheelchair, the foot rest will deflect inwardly.

9. An improved wheelchair according to claim 8 wherein each said foot rest is mounted for pivotal movement about a substantially horizontal axis which is inclined to the horizontal, whereby the foot rest may be swung upwardly to approximately vertical positions for transporting purposes.

10. An improved wheelchair according to claim 1 wherein said securing means comprises two pairs of longitudinal spaced upstanding abutment pins on said base frame, the pins of each pair being transversely aligned, one adjacent each side of said base frame, said pins being constructed and arranged so as to restrain said intermediate support frame against movement in one longitudinal direction relative to said base frame, and also against lateral movement relative to said base frame.

11. An improved wheelchair according to claim 10 wherein each said abutment pin terminates at its upper end in a rearwardly directed portion, the arrangement being such that with said sub-frame located on top of said base frame, the rearwardly directed portions of the pins project across the upper walls of respective cross frame members of the sub-frame, whereby the sub-frame is restrained againt vertical displacement relative to the base frame.

12. An improved wheelchair according to claim 10 or 11 wherein said securing means further comprises a pivoted locking lever which is provided with a clamp plate which lockinglyengages between the sub-frame and the base frame to thereby restrain said intermediate subframe against movement in the opposite longitudinal direction.

13. An improved demountable wheelchair substantially as hereinbefore described and illustrated in the accompanying drawings.