NZ201826A - Folding wheelchair frame:scissor action with rear post to seat sliding connection - Google Patents

Description

2Q1$26 ftjl. P&TESfff arm i 1 1 NOV 1983 .' * -V* Patents Form No.5.

Patents Act 1953 No.201826 COMPLETE SPECIFICATION Date: 7.9.82 "Folding Wheelchair".

WE, BETSTONE INDUSTRIES LIMITED, of 75 Montreal Street, Christchurch, New Zealand, a company organised and existing under the laws of New Zealand, hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly . described in and by the following statement:- 201823 The present invention relates to a folding wheelchair and to a sliding and/or pivotal connection for a folding wheelchair.

In one aspect the invention consists in a folding wheelchair frame comprising two side frame structures spaced from each other and from which wheels of the wheelchair are to be directly or indirectly dependent, each side frame structure including a front upstanding post of a square box section and an upstanding rear post, said side frame structures being capable of being moved towards and away from each other, cross linking members in the form of a pair of arms pivoted to define an X shape, the pivot being at the centre of the X and having a lower end of each arm pivoted to a lower member of each side frame structure about a pivot axis parallel to that at the centre of the X /Shape, and a seat structure vertically slideable relative to each side frame structure and the upstanding post structures thereof, said seat a structure being in two parts with each part for locating an and of "m£ seat which will be required to deform or fold when the frame is "folded" by moving said side frames towards each other, each said part of said seat structure having means captive on but slidable upwardly and downwardly along the rear upstanding post of each side frame structure and at the front thereof a downwardly directed member of round tubular cross section olideable receivable within the upstanding square box section of the front upstanding post, an upper end of each arm of the X shape being pivoted to its respective said part of the pa/feMel .. seat structure about a pivot axis .parallel to the pivot axis at thep 201826 centre of the X, the construction and arrangement being such that when in an open condition with the side frame structures apart the seat structure is at a particular height with respect to the side frames but when the structure is "folded" in order to bring the side frame structures towards each other, the seat structure is higher relative to both the front and rear post structures of each side frame, the sliding move- cr #ie piuafma of +He iowev airm ments at the front^being of a four point contact between the downwardly directed circular tube and the inner surface of the upstanding or betwee.fi cirtitUr -fubc enMi square box section of the front posts^ ir&fpectivclij .

In a further aspect the invention consists in a wheelchair embodying the form previously described.

The present invention further provides a sliding or pivotal connection as described above.

By way of example only, a preferred embodiment of the present invention is described in detail, with reference to the accompanying drawing, in which:- Fig.l is an isometric view of part of a wheelchair in accordance with the present invention; and Figs.2 and 3 are sections on lines II-II and III-III respectively of Fig.l.

Referring to the drawings, a wheelchair 2 comprises a back portion 3 and a seat portion 1+ mounted on a large not shown not shown pair of wheels/secured to axles 5 and a pair of castor wheels/ secured to arches 6. The wheelchair is fitted with brakes, arm-rests, footrests and other standard fittings, alis=e£*which are omitted from the drawing for clarity. /v I -8 JAN 1987 201826 The main frame of the wheelchair 2 comprises a pair of rear vertical posts 7, a pair of front vertical posts 8, and two pairs of side members 9 (upper) and 10 (lower). Each of the upper side members 9 is secured horizontally between i the corresponding front and rear vertical posts S and 7 just below the seat portion 4.

Each of the lower side members 10 is secured; adjacent one end to the end of the corresponding rear vertical post 7 and at the other end is curved upwards to form an arch 6 over the castor wheel and is secured to the end of the corresponding front vertical post 8. The upper ends of the rear vertical posts 7 are bent to form handles (not shown) and the axles 5 of the wheels are secured to the rear vertical posts 7 below the seat portion 4. The back portion 3 is formed by fabric 11 secured between the upper parts of the posts 7* The seat portion 4 is formed by a pair of side supports 12 parallel to the side members 9. The front of each side support 12 is mounted on a length of circular-cross- section tube 13, which is co-axial with, and received within, the corresponding front post $, which is of square-cross- section; the external diameter of tube 13 is equal to the internal length of the side of the square of post 8, so that there is contact between the tubes 8 and 13 at four points •a' (Fig.2). The rear of each side support 12 ends in a bracket 15 with a part-circular cross-section, the bracket being arranged to grip the square cross-section post 7, with point contact at four points 'b' (Fig.3). but be slidable up and down that post 7 as the chair is closed or opened. 201826 The centre of the seat portion 4 is supported by an X-shaped pair of arms 16, pivoted in the centre of the'X', with the upper end of each arm 16 secured to the corresponding side support 12 and the lower end of each arm 16 is secured to part of the corresponding side member 10.

Each side member 10 comprises square-cross-section portions 20, 21 at each end, with a circular-cross-section portion (not visible) rigidly mounted between them. A square-cross-section tube 23 is mounted on the circular-cross-section portion, co-axial therewith. The internal length of the side of the tube 23 is equal to the external diameter of the circular-cross-section portion, so that there is point contact between them at four points.

The necessary rotation at the upper end of the "X" is effected by rotatably connecting the side support 12 to both the bracket 15 and the tube 13.

When the wheelchair 2 is in use, the weight of the person sitting on the seat portion keeps the X-shaped arms 20182® expanded, as shown in Fig.l. To fold the chair, the handles are moved towards each other (i.e. in the direction of arrows A in Fig.l) or the chair is tilted to one side so that the chair's own weight tends to move the sides of the chair towards each other. As the arms 16 of the X-shaped portion move towards each other, the lower end of each arm pivots freely, with the tube 23 pivoting on the inner circular portion. At the same time, the seat portion 4 rises vertically relative to the vertical posts 7 and 8, with the tubes 13 sliding in the front posts $ and the brackets 15 sliding on the rear posts 1. In the fully closed position, the rear posts 7 contact each other.

Folding the wheelchair is much easier than with a conventional chair, because of the point contact between the pairs of sliding or pivoting members. Preferably, the front and rear posts 8 and 7 and the side members 9 and 10 are of square-cross-section tube, because it is easier to weld two square tubes together than to weld two round tubes together. Also, if external fittings are welded to the corners of square tube, there is little chance of weld penetrating fouling a circular-cross-section tube inside the square tube, since there is point contact only between the two tubes. This in turn means that a welded stainless-steel construction becomes feasible, whereas if sliding and pivoting connections are made from coaxial circular-cross-section tubes, stainless-steel .construction is difficult because stainless steel welds are especially prone to excessive weld penetration. - 6 -" * " 201826 It will be appreciated that instead of the above-described coaxial round-tube-in-square-tube joints, the joints could be constructed as square-tube-in-round-tube to achieve the same point contact. _ 7- --Jfr - 201826

Claims (3)

WHAT WE CLAIM IS: AJE&S <-r} fa V

1. A folding wheelchair frame comprising two side frame structures spaced from each other and from which wheels of the wheelchair are to be directly or indirectly dependent, each side frame structure including a front upstanding post of a square box section and an upstanding rear post, said side frame structures being capable of being moved towards and away from each other, cross linking members in the form of a pair of arms pivoted to define an X shape, the pivot being at the centre of the X and having a lower end of each arm pivoted to a lower member of each side frame structure about a pivot axis parallel to that at the centre of the X shape, and a seat structure vertically slideable relative to each side frame structure and the upstanding post structures thereof, said seat ..... structure being in two parts with each part for locating an ond of tK;*-". seat which will be required to deform or fold when the frame is "folded" by moving said side frames towards each other, each said part of said seat structure having means captive on but slidable upwardly and downwardly along the rear upstanding post of each side frame structure and at the front thereof a downwardly directed member of round tubular cross section .alidoabro receivable within the upstanding square box section of the front upstanding post, an upper end of each arm of the X shape being pivoted to its respective said part of the pavuWtf/ seat structure about a pivot axis pagalled to the pivot axis at the centre of the X, the construction and arrangement being such that when in an open -8- 201826 condition with the side frame structures apart the seat structure is at a particular height with respect to the side frames but when the structure is "folded" in order to bring the side frame structures towards each other, the seat structure is higher relative to both the front and rear post structures of each side frame, the sliding move- or H*£ (oLver ariM ments at the front, being of a four point contact between the down- A wardly directed circular tube and the inner surface of the upstanding or batwee» eiVen-W -fube uurttnU ■utuaye on square box section of the front posts^ ly .

2. A frame as claimed in claim 1 substantially as hereinbefore described with reference to any of the accompanying drawings.

3. A wheelchair of a kind substantially as hereinbefore described embodying a frame as claimed in claim 1 or 2. D ATED TH1S&*1 DAY OF 19,<^ A. J. PARK & SON PER AGENTS FOR THE APPLfCANTS