GB2126537A

GB2126537A - A foldable wheelchair

Info

Publication number: GB2126537A
Application number: GB08318131A
Authority: GB
Inventors: Wilhelm Meyer
Original assignee: Meyra Krankenfahrzeug Fabrik Wilhelm Meyer GmbH and Co KG
Current assignee: Meyra Krankenfahrzeug Fabrik Wilhelm Meyer GmbH and Co KG
Priority date: 1982-07-22
Filing date: 1983-07-05
Publication date: 1984-03-28
Also published as: GB2126537B; DE3227365A1; BE897210A; GB8318131D0; FR2530458A1

Abstract

A foldable wheelchair has lateral frame members (10,11) which accommodate wheels (12,13) and are pivotable relative to one another in the frame member planes in dependence upon the surface of the ground, by means of cross-pieces (14, 15) of which the lower ends are pivotally mounted on lower supporting tubes (17) of the frame members (10, 11), and the upper ends are rigidly mounted on seat tubes (18). Each seat tube (18) is rotatably mounted in two hinged sleeves (20) the sleeves (20) being mounted on the upper ends of guided guide rods which are vertically displaceable; to reduce friction occuring as a result of the displacement of the guide rods when the wheelchair is retracted and extended, and, each guide rod is the rail (21a) of a ball guidance means (21), its other rail being mounted inside the associated frame member (10, 11). <IMAGE>

Description

SPECIFICATION Atoldable wheelchair The invention relates to a foldable wheelchair having lateral frame members which accommodate wheels and are pivotable relative to one another in the frame member planes in dependence upon the surface of the ground, such frame members being interconnected by means of connecting cross-pieces which are disposed in a cross-over manner, the lower ends ofthe cross-pieces being pivotally mounted on lower supporting tubes of the frame members, and the upper ends ofthe cross-pieces being rigidly mounted on seat tubes, each seattube being mounted in two hinged sleeves so as to be rotatable about its axis, such hinged sleeves being mounted on the upper ends of guided guide rods which are vertically displaceable.

Awheelchairofthistype is disclosed in German PS No. 1 943 339. When this wheelchair is telescoped or extended, the vertical guide rods are displaced within vertical guide sleeves which are mounted on the frame members, the vertical guide rods being appropriately inserted into such guide sleeves. These displacement movements produce considerable sliding friction between the outer surfaces of the guide rods and the innersurfaces of the guide sleeves, so that a large amount of force has to be exerted in order to telescope or extend the two frame members of the wheelchair.

The present invention seeks to develop such a foldable wheelchair so that it can be telescoped or extended moreeasily in order to reduce the force required to perform these operations.

According to the invention, this object is achieved in that each guide rod is the rail of a ball guidance means, its other rail being mounted within the associated frame member. The use of ball guidance means, wherein ballsact as roll bodies, one end being supported on an inner rail and the other end carrying an outer rail, results in the balls rolling along the surfaces with which they are in contact when the outer rail is displaced relative to the inner rail. This causes the friction occurring during the relative displacement movement to be very much lowerthan the friction which occurs when adjacent surfaces slide relative to one another.

Each guide rod is preferablythe outer rail ofthe ball guidance means, its inner rail being mounted within the associated frame member.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawings, in which: Fig. lisa side elevational view of a foldable wheelchair in accordance with the invention; Fig. 2 is a schematic, vertical cross-sectional view taken along the line ll-ll of Fig. 1 after the wheelchair has been partially telescoped; Fig. 3 is a partially fragmented view of a ball guidance means; Fig. 4 is a cross-sectional viewtaken along the line IV-IV of Fig. 3; and Fig. 5 is an end view of an alternative ball guidance means.

The foldable wheelchairfor persons who cannot walk comprises two identical lateral frame members 10 and 11 which are variably spaced from each other and are made from tubes or the like. Each rear, lower region ofthese lateral frame members 10and 11 is provided with wheels, more especially manually operable drive wheels 12, and the front, lower region of each frame member 10 and 11 is provided with a bogie wheel 13 which is pivotable about a vertical axis and has a smaller diameterthan the drive wheel.

The two frame members 10 and 11 are movably interconnected by means of two cross-over connecting cross-pieces 14and 15which are preferably provided in the central region ofthe respective frame member; such cross-pieces 14 and 15arealsoformed by tubes or the like and are movable in a scissor-like manner about a common hinge axle 16 at their point of intersection. The lower ends of the two connecting cross-pieces 14 and 15 are pivotably mounted, in the lower portions oftheframe members 10 and 11, on lower supporting tubes 17 oftheframe members 10 and 11.

The upper ends of the connecting cross-pieces 14 and 15 areT-shaped and, in such case, can be combined to form theirT-shape by means of seat tubes 18 which extend at right angles to the longitudinal axis ofthe cross-pieces, such seat tubes 18 serving to accommodate a flexible seatsurface 19.

When thetwoframe members 10 and 11 ofthe wheelchair are telescoped or extended, therefore, the seattubes 18 mounted on the upper ends ofthe connecting cross-pieces 14and 15 rotate also about their longitudinal axis while they pivot aboutthe hinge axle 16.

Each seat tube 18 is mounted in two hinged sleeves 20 which are disposed behind each other and are appropriatelyfitted onto the seat tube 18. The upper ends oftwo outer rails 21 a are mounted on the hinged sleeves 20, and such outer rails 21 a are guided in a vertically displaceable manner on each frame member 10, 11. The outer rails 21a belong to ball guidance means 21, the inner rails 21 bthereof being vertically mounted on the frame members 10 and 11. When the connecting cross-pieces 14 and 15 pivot about the hinge axle 16 in a scissor-type manner in orderto telescope or extend the wheelchair, the outer rails 21 a ofthe ball guidance means 21 are vertically displaced.

The two lateral frame members 10 and 11 are interconnected by means of the connecting crosspieces 14 and 15so as to be vertically displaceable relative to each other, and such frame members 10 and 11 are pivotable relative to each other due to this vertically displaceable connection, so that, when the ground is uneven, a frame member 10 or 11, respectively, can alter position in the frame member plane relative to the other frame member 11 or 10, respectively, and this permits the chair to compensate forunevenground.

Forthis purpose, the two lateral frame members 10 and 11 are kept rotatable relative to each other by means of a hinge joint 22 disposed at the point of intersection oftheconnecting cross-pieces 14 and 15.

The two connecting cross-pieces 14 and 15 are split at the intersecting region and are each adapted so as to be movable about a rotary axle 23,24 which extends transverselyto the direction oftravel parallel to the axles of the drive wheels 12, the two connecting cross-pieces 14 and 15 being interconnected by the hinge axle 16. For the additional features of the hinge joint 22, reference is made to German PS No.

1943339.

In orderto mountthe inner rail 21b of each ball guidance means 21 in the associated frame member 10,11, mounting lugs are provided lower mounting lug 28 and an upper mounting lug 29which are connected to the inner rail 21 b. Each inner rail 21bis mounted on the lower supporting tube 17of the associated frame member 10, 11 via the lower mounting lug 28, while the inner rail 21 b is mounted on a longitudinal tie-rod 30 via the upper mounting lug 29, such a longitudinal tie-rod 30 being fixedly disposed within the frame member.

The outer rail 21 a ofthe ball guidance means 21 is formed by a square tube having rounded-offcorner regions. Four rows of balls 31 disposed behind one another are provided in the square tube, the balls 31 rolling along the innersurface ofthe outer rail 21a longitudinally of the rounded-off corners thereof. The balls31 are guided in a cage member 32 which also hastheform of a square tube.

The cage member 32 surrounds a square-shaped rod which forms the inner rail 21 band is provided with guide grooves longitudinally of its edge lines, such guide grooves corresponding to the diameter of the balls 31.The balls 31 roll in these guide grooves longitudinally ofthe inner rail 21 b. The inner rail 21 b is connected to a cover rail 34 by means of a web 33, and the ends ofthe cover rail 34 are welded to the mounting lugs 28 and 29. In orderto permit this connection to extend from the inside of the cage member 32 to the outside of the outer rail 21 a, the cage member32 is provided with a longitudinal slot 35 and the outer rail 21 a is provided with a longitudinal slot 36, and the web 33 extends through such slots 35 and 36.

The ball guidance means 37 as illustrated in Fig. 5 of the drawing comprises onlytwo rows of balls 38 which are disposed rectilinearly behind one another and are retained in a cage member 39. The balls 38 roll along an inner rail 40, surrounded by the cage member 39, and along an outer rail 41 which surrounds the cage member 39.

Claims

1. Afoldablewheelchair having lateral frame members which accommodate wheels and are pivotable relative to one another in the frame member planes in dependence upon the surface ofthe ground, such frame members being interconnected by means of connecting cross-pieces which are disposed in a cross-over manner, the lower ends ofthe cross-pieces being pivotally mounted on lower supporting tubes of theframe members, and the upper ends of the cross-pieces being rigidly mounted on seat tubes, each seattube being mounted in two hinged sleeves so as to be rotatable about its axis, such hinged sleeves being mounted on the upper ends of guided guide rods which are vertically displaceable, in which each guide rod is the rail of a ball guidance means, its other rail being mounted inside the associated frame member.

2. Awheelchairas claimed in claim 1, in which each guide rod is the outer rail ofthe ball guidance means, its inner rail being mounted within the associated frame members

3. Awheelchairas claimed in claim 1 or2, in which the inner rails are mounted within the frame member by means of mounting lugs disposed on the ends of the inner rails, the lower mounting lugs being detachably mounted on the supporting tube and the upper mounting lugs being detachably mounted on a longitudinal tie-rod retained within the frame member.

4. Awheelchairas claimed in claim 1,2 or3, in which each ball guidance means is provided with two rows of balls which serve as roll bodies and roll along the inner rail and the outer rail, such rows of balls being retained in a cage member having a U-shaped profile.

5. Awheelchairasclaimed in any one of claims 1 to 4, in which each ball guidance means is provided with four rows of balls which serve as roll bodies, such rows being retained in a cage member in the form of a square tube and each row being disposed longitudinally of an edge of such tube, and the balls roll along a square rod, acting as the inner rail and having guide grooves atthe edges, and along the rounded-off inner edges of a square tube which acts as the outer rail, the inner rail being connected to the mounting lugs by means of a moulded-on web which extends through longitudinal slots formed in the cage member and the outer rail.

6. A foldable wheelchair, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.