GB2209312A - Wheelchairs - Google Patents

Abstract

A collapsible wheelchair (10) in which a pair of side frames (12, 13), Fig 1, which carry the front wheels (80, 82) are foldable in opposite directions across the wheelchair, to provide a simple light and robust construction. Mounting means for the rear wheels (96, 98) is carried on a rear frame (11) and is not required to move during the folding operation, the side frames (12, 13) being pivotally secured to the rear frame (11) so as to fold about axes adjacent the rear frame after seat frame (32) has been raised. <IMAGE>

Description

WHEELCHAIRS This invention relates to collapsible wheelchairs.

A collapsible wheelchair is normally constructed with a tubular steel framework and incorporates a pair of rear wheels and a pair of front wheels of smaller diameter, the front wheels being normally mounted as castors. In order to enable such a chair to be stored it is usual for it to be arranged to fold about a longitudinal axis by means of a scissors mechanism, the two sides of the chair being brought together.

The folding mechanism tends to be expensive, and one object of the present invention is to provide a relatively inexpensive collapsible wheelchair.

According to the invention a wheelchair has a rear frame provided with mounting means for a pair of rear wheels, and a pair of side frames each arranged to carry one of a pair of front wheels, the side frames being pivotally secured to the rear frame for inward transverse folding movement of the side frames in opposite directions across the wheelchair towards the rear frame, about axes adjacent the rear frame, to enable the wheelchair to be collapsed without movement of the mounting means for the rear wheels.

The pivotal axes of the side frames are substantially vertical, i.e. arranged to lie in an upright direction relative to a horizontal surface on which the wheelchair stands, or make only small angles with the upright direction. To achieve satisfactory folding, the pivotal axes may be located forwardly of the rear frame by a short distance, and the pivotal axis of one of the side frames is preferably located further forwardly than the other.

Locking of the wheelchair in the erect state is preferably achieved by a mechanical interlock between the side frames and a seat frame which is pivoted to the rear frame for movement between a raised position in which the wheelchair may be collapsed and a lowered position in which the seat frame mechanically interlocks with the side frames to hold the wheelchair erect.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a diagrammatic perspective view showing a wheelchair in accordance with the invention, in the erect state; Figure 2 is a diagrammatic perspective view of the wheelchair of Figure 1 in the collapsed state; Figure 3 is a diagrammatic side elevation of the wheelchair of Figures 1 and 2 in the erect state; Figure 4 is a diagrammatic plan view corresponding to Figure 3, with some details omitted, showing part of the wheelchair in the collapsed state;; Figures 5 and 6 are fragmentary side and front views respectively showing parts of an interlocking mechanism for a seat frame and a side frame forming part of the wheelchair of Figures 1 to 4, and Figures 7 and 8 are fragmentary plan views showing a pivot forming part of the wheelchair of Figures 1 to 6, in the erect and collapsed positions respectively.

A wheelchair 10 comprises a rear frame 11 and side frames 12 and 13 constructed from tubular steel members. The rear frame 11 comprises side tubes 15 and 16 interconnected at their upper ends by a top tube 18 which constitutes a handle by which the wheel -chair can be pushed, and at their lower ends by a bottom tube 20. Upper portions 15a, 16a constitute a backrest support portion of the rear frame to which a backrest 22 of suitable material is attached in conventional manner, and horizontal pivots 30 are provided to secure a seat frame 32 to the rear frame 11 so that the frame 32, which is formed from a U-shaped tube 34 and cross-brace tube 36 may be tilted from the substantially horizontal position shown in Figures 1 and 3 to the substantially vertical position shown in Figures 2 and 4 (and in dotted lines in Figure 3).

The seat frame 32 is covered with flexible sheet material 38 in conventional manner, the cross-brace tube 36 being located adjacent the forward ends of the side limbs of the seat frame to prevent deformation of the seat frame when a user is sitting in the chair.

The side frames 12, 13 comprise vertically extending tubes 40, 41 respectively which are bent to form integral arm rest tubes 44, 46 to which arm rest pads 47, 48 are secured. Adjacent the junctions between the vertical tubes 40, 41 and the arm rest tubes 44, 46, inturned abutments are provided to interlock with the forward ends of the seat frame tube 34. In Figures 5 and 6 an abutment 50 associated with the side frame 12 is shown (a similar abutment is provided on the side frame 13), the abutment 50 being provided by a stub tube 51 brazed to the tube 40 and having brazed-on locating flanges 52, 53.Figures 5 and 6 show the seat frame 34 in a partially raised state, and it will be noted that the forward ends of the seat frame tube 34 have brazed-on semi-circular forks 54 constituting depending formations for engage -ment with the stub tubes 51 in the lowered position of the seat where the seat frame thus serves to lock the two side frames in their required positions in the erect state of the wheelchair.

The side frames 12, 13 also include lower tubes 60, 61 brazed at their forward ends to the vertical tubes 40, 41 respectively. The rear ends of the respective arm rest support tubes 44, 46 and lower tubes 60, 61 of the side frames are secured to vertical pivots attached to stub tubes brazed to the side tubes of the rear frame 11 and projecting forwardly therefrom.

Although of various lengths, for reasons to be described, the stub tubes attached to the rear frame to carry the side frame pivots are generally similar in construc -tion, and only that associated with the armrest support tube 44 of the side frame 12 is shown in Figures 7 and 8. The stub tube 66 is brazed to the rear frame and projects forwardly, its free end being brazed to one end 67 of a channel-section bracket 68. The other end 69 of the bracket 68 provides a pivotal mounting for the tube 44, a screw 70 passing vertically through holes in the upper and lower flanges of the channel 68 and through similar holes in the associated end of the tube 44 (which is reinforced internally by a solid cylindrical metal insert) to act as a pivot, and a locknut (not shown) is provided beneath the bracket, on the lower end of the screw.The arrange -ment is such that the tube 44 is free to pivot inwardly, transversely across the rear frame 11 of the wheelchair, but is limited in its outward movement by its engagement with a stop provided by the base of the channel-shaped bracket 68.

From Figure 4 it will be noted that the pivots 75 (both upper and lower) for the side frame 12 are positioned further forwardly from the rear frame 11 than the corresponding pivots 76 associated with the side frame 13. This provides optimal usage of the available space adjacent the rear frame for folding -in of the two side frames.

The folded position of the side frames, shown in dotted lines in Figure 4, is achieved by raising the seat frame, turning associated front wheel castors 80, 82, which are carried in swivel mountings secured to the lower ends of the tubes 40, 41, as indicated by the respective arrows A, B in Figure 4, and inward transverse folding movement of the side frames 12 and 13 in opposite directions across the wheelchair towards the rear frame as indicated by the arrows C and D.

Footrest assemblies 90, 92 are provided in conventional manner on pivotal supports attached to the tubes 40, 41 respectively of the side frames.

The footrests are, in accordance with conventional practice, arranged to be held in a stable position as shown in Figure 1 and are foldable to a second stable position as shown in Figure 2 (they have been omitted from Figure 4 for clarity). The mechanism to enable the footrests to be folded is conventional and has therefore not been illustrated in detail.

Rear wheels 96, 98 are freely rotatably mounted on stub axles brazed to the side tubes 15, 16 of the rear frame 11 in conventional manner, and brake mechanisms 100, 101, again of conventional type are mounted on the rear frame 11 to operate against the tyres of the respective wheels 96, 98.

It will be appreciated that various modifications may be made to the embodiment described above without departing from the invention, the scope of which is defined in the appended claims. For example in the embodiment described the rear wheels are of small diameter and are intended to remain in position after the chair has been folded : in an alternative construction the rear wheels may be of larger diameter and of the quick -release type for removal and separate storage when the chair is folded, but as in the embodiment described above the mounting means for the rear wheels remains in a fixed position on the rear frame during folding.

In another modification, instead of the armrest supports being integral with the side frames the tubes 44, 46 may be located at the level of the lowered seat frame and detachable armrests may be provided.

The wheelchair described above is simple in construction, light in weight, and robust in operation; it is easy to collapse and may readily be secured in the collapsed state by appropriate detachable check straps. In the collapsed state it is compact and readily stored, e.g. in the luggage compartment of a small car. The principle of the invention is also applicable to powered wheelchairs e.g. of the kind incorporating an electric motor and battery and a suitable control system.

Claims (9)

CLAIMS:

1.: A wheelchair having a rear frame provided with mounting means for a pair of rear wheels, and a pair of side frames each arranged to carry one of a pair of front wheels, the side frames being pivotally secured to the rear frame for inward transverse folding movement of the side frames in opposite directions across the wheelchair towards the rear frame, about axes adjacent the rear frame, to enable the wheelchair to be collapsed without movement of the mounting means for the rear wheels.

2. A wheelchair according to Claim 1 wherein the pivotal axes about which the side frames are foldable are located forwardly of the rear frame.

3. A wheelchair according to Claim 2 wherein one of the pivotal axes about which the side frames are foldable is located further forwardly of the rear frame than the other of the pivotal axes.

4. A wheelchair according to any of Claims 1 - 3 wherein a seat frame is pivoted to the rear frame for movement between a raised position in which the wheelchair may be collapsed and a lowered position in which the seat frame mechanically interlocks with the side frames to hold the wheelchair erect.

5. A wheelchair according to Claim 4 wherein the seat frame is generally of U-shape with side limbs thereof resting, when the seat frame is in its lowered position, on inturned abutments carried by the side frames, depending formations being provided on the seat frame to interlock with the respective abutments.

6. A wheelchair according to Claim 5 wherein the side limbs of the seat frame are interconnected by a cross-brace located adjacent their forward ends.

7. A wheelchair according to any of Claims 1 to 6 wherein the side frames are foldable about pivots provided with stop means to limit outward movement of the side frames.

8. A wheelchair according to Claim 7 wherein stop means for a side frame pivot comprises a channel-section bracket secured to the rear frame, the outward movement of the associated side frame being limited by its engagement with a base portion of the bracket.

9. A wheelchair constructed and arranged substan -tially as described in the Description and illustrated in the accompanying drawings.