GB2122144A

GB2122144A - Hand propelling ring for a wheelchair

Info

Publication number: GB2122144A
Application number: GB08311650A
Authority: GB
Inventors: Victor Leroy
Original assignee: SINCOPLAS
Current assignee: SINCOPLAS
Priority date: 1982-05-05
Filing date: 1983-04-28
Publication date: 1984-01-11
Also published as: GB8311650D0; GB2122144B; FR2526311A1; FR2526311B1; DE3316002A1; BE896639A

Abstract

A hand propelling ring for fixing co-axially to a main wheel of a wheelchair is made of expanded cellular plastics material by expansion moulding and has fixing elements 7 for fixing it to the wheel incorporated in it by insert moulding. To enable the ring to be easily gripped manually it has concave side surfaces 4, 8, a convex radially outer surface 3 and a radially inner surface comprising two portions 2 which are straight as seen in section and are connected by a convex fillet 6. The ring is light, robust and impact resistant. Also owing to its cross-sectional shape it is much easier to grip than a conventional tubular metal ring of circular section. <IMAGE>

Description

SPECIFICATION Hand propelling ring for a wheelchair Some wheelchairs for physically handicapped persons are driven by hand propelling rings which are hoops fixed one to each of the main wheels of the chair so that they cannot rotate relative to the wheels. By means of these rings it is possible for the user of the chair to move and to steer the - chair.

Conventional propelling rings are usually formed of metal and are tubular and of circular cross-section. They have certain disadvantages, including excessive weight and fragility under shocks which cause them to become dented in use, and their circular cross-section- is not very suitable for satisfactory gripping by the hands.

The object of the present invention is to overcome these disadvantages and to this end, according to this invention a hand propelling ring for a wheelchair is made of moulded plastics material and includes fixing elements spaced apart around it for fixing it to the wheel of the wheelchair.

The propelling ring also preferably includes the following advantageous features:- The plastics material is expanded and honeycombed or cellular; The ring is formed by expansion moulding; The cross-section of the ring on a radial plane has an internal radial surface portion, an external radial surface portion and an external axial surface portion disposed between the internal and external radial surface portions, these various surface portions having the following curvatures: The part of the internal radial surface portion connected to the external axial surface portion is substantially flat; The external radial surface portion has a convex curvature; and The axial external surface portion has a concave curvature; The magnitude of the curvature of the external axial surface portion is substantially greater than that of the external radial surface portion and preferably equal to substantially twice the latter; The surface portions are connected, one to the other, by convex rounded fillets; The fixing elements are integrally connected to the ring by being locked into it by insert moulding into the plastics material.

The invention also includes a wheelchair having tvfo main wheels each of which has a propelling ring in accordance with the invention fixed co axially to it.

An example of a propelling ring in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure 1 is an elevation of the ring from the external side, that is the side which, in use, is directed away from the wheel of the wheelchair; Figure 2 is a section to a larger scale on the line Il-Il of Figure 1; and Figure 3 is a section to a larger scale on the line Ill-Ill of Figure 2.

The propelling ring is a kind of hoop of plastics material, having an axis 1. The external face of the ring, that is the face which in use, is directed away from the wheel of the wheelchair to which the ring is fixed, is shown in Figure 1. This is the face which is visible when this ring is fixed to the wheel of a wheelchair, and on this external face three distinct surface portions can be distinguished: An internal radial surface portion -2- directed towards the axis 1; An external radial surface portion 3 remote from the axis 1; and An external axial surface portion 4, radial two the axis; The section of Figure 2, through a radial plane 1 6 containing the axis 1, enables these various surface portions, which coincide with the periphery of this section, to be better identified.

The following arrangements will be noted: The radial section of the ring is symmetrical about a plane 5 perpendicular to the axis 1; By reason of this symmetry, only the axial surface portion corresponding to the external face are described in detail, the internal axial surface portion being similar; The surface portions 2 extend over the radially inner or upper face of the section and are substantially rectilinear as seen in section; The surface portion 3 extends on the radially outer or lower face and is a circular arc of radius 2R (16 mm for the example shown) defining a convex face; The surface portion 4 extends radially and is a circular arc of radius R (equal to 8 mm in the example shown), defining a concave face; Convex, circular arcuate connecting fillets 6 join these various surface portions together.

Four fixing elements 7, enabling the propelling ring to be fixed to the wheel of a wheelchair, are rigidly incorporated in the ring and are distributed at uniform angular intervals around the internal axial surface portion 8 of the ring.

Each element 7 comprises a shank 9, in which a screw threaded bore 10 is formed, and two lugs 1 3 which extend laterally from the end of the shank remote from the entry orifice 11 of the bore perpendicularly to the axis 1 2 of this bore. The axis 1 2 is perpendicular to the plane 5 and is located substantially at equal distances from the apices 14 of the upper fillet connecting together the two surface portions 2 and of the surface portion 3. It is also substantially at the centre of the internal axial surface portion 8.

The propelling ring is formed by moulding an expanded cellular plastics material 1 5. Before moulding, each fixing element 7 is placed in position so that, at the instant of moulding, the lugs 13 and a portion of the shaft 9 are set in the mass of the plastics material during expansion of the material and remain locked in the latter.

The principal advantages of the example described are the following: The propelling ring is light, because the plastics material 1 5 is expanded; The handrail is not damaged due to denting, since it possesses the elasticity conferred upon it by the expanded plastics material; It does not rust and can in addition be tinted to any desired colour; The shape of its cross-section can be well adapted to the requirements for good manual gripping, and this can be done regardless of the user (such as a child, adult, or old person); The definitive positioning of the fixing elements 7 by the operation of insert moulding itself is very simple and very reliable.

Claims

1. A hand propelling ring for fixing to and rotating a wheel of a wheelchair, the ring being made of moulded plastics material and including fixing elements spaced apart around it for fixing it to the wheel of the wheelchair.

2. A ring according to Claim 1, in which the plastics material is expanded and cellular.

3. A ring according to Claim 2, which is made by expansion moulding.

4. A ring according to any one of Claims 1 to 3, in which in cross-section in a radial plane, the ring has an internal radial surface portion, an external radial surface portion and an external axial surface portion disposed between the internal and external radial surface portions, these various surface portions having the following curvatures:- The part of the internal radial surface portion connected to the external axial surface portion is substantially flat; The external radial surface portion has a convex curvature; and The axial external surface portion has a concave curvature.

5. A ring according to Claim 4, in which the magnitude of the curvature of the external axial surface portion is substantially greater than that of the external radial surface portion.

6. A ring according to Claim 5, in which the magnitude of the curvature of the external axial surface portion is equal to substantially twice that of the external radial surface portion.

7. A ring according to any one of Claims 4 to 6, in which the said surface portions are connected together by convex, rounded fillets.

8. A ring according to any one of Claims 1 to 7, in which the fixing elements are rigidly incorporated in the ring by being locked into it by insert moulding.

9. A ring according to Claim 8, in which there are four fixing elements equally spaced around the ring and each element comprises a shank with a screw threaded bore protruding from one side of the ring and lugs which are integral with the shank and embedded in the ring extending circumferentially thereof.

10. A ring according to Claim 1, substantially as described with reference to the accompanying drawings.

11. A wheelchair having two main wheels, each of which has a ring in accordance with any one of the preceding Claims fixed co-axially to it.