GB2112330A - Stair vehicle - Google Patents

Abstract

The vehicle - e.g. a wheelchair - has groups of wheels mounted on a spider for rotation about a central axis to enable the vehicle to ascend or descend stairs or steps. Stabilisation of the vehicle is effected by a pivoted projecting arm or skid (27) which bears directly on the stairs to reduce the risk of the vehicle tipping. The arm may be lockable (by, as shown a hinged strut (30)) to the frame (1) to stabilise the entire vehicle, or in another arrangement (not shown) may be pivotable along with a drive motor for the vehicle, to transmit the motor or braking torque directly to the stairs. <IMAGE>

Description

SPECIFICATION Stair vehicle The present invention reiates to a device for use in moving a load up or down a stepped path such as a staircase. It is particularly, though by no means exclusively, applicable to invalid chairs.

According to the present invention there is provided a device for use in moving a load up or down a stepped path, comprising a structure for receiving the load, at least one support element rotatably mounted thereon and having at least three symmetrically disposed wheels whereby, in use, the wheels cooperate with successive steps of path, and an elongate forwardly extending stabilizing element secured for pivotal movement between an upper, retracted position and a lower position in which, in use, it bears on the stepped path.

In one preferred arrangement, means are provided to lock the stabilising element in its lower position.

The locking means may comprise a hinged strut connecting the stability element to the structure, the movement of the hinge being limited in one direction whereby the strut is movable between a folded position in which the stabilising element is retracted and an over-centre position in which the stabilising element is locked in its lower position.

Preferably the strut is spring-biased toward its over-centre position.

Another arrangement includes a motor arranged to drive the support element(s), the motor being pivotally mounted about an axis substantially coincident with that of the support element(s) and the stabilising element being secured for pivotal movement together with the motor.

The device may also include foot means secured to each support element adjacent the corresponding wheel, the foot means being clear of the circumference of the wheel at two regions so that the wheel can roll freely on a plane when the support element is positioned with the wheel and respectively one or other of the adjacent wheels in contact with the plane, and having engagement portions located forwardly of the said two regions so as, when the support element is rotated forwardly of the said position, to engage the plane to prevent rolling movement.

Normally the clear regions will be disposed symmetrically on each side of a radius of the support member passing through the axis of the wheel in question; one engagement portion being on this radius and the other lying forwardly of the forwardmost of the two clear regions. "Forward" is with reference to the direction downwardly of the stepped path: where the device has a handle, usually the device will move up the path handlefirst. If the device does not have a preferred direction, then naturally three engagement portions should be provided, respectively rearwardly, between, and forwardly of the two clear regions. Indeed, it may sometimes be convenient to provide three engagement portions even in devices having a preferred direction.

In one preferred arrangement, the foot means takes the form of a further wheel, non-rotatabiy mounted on the support member, coaxial with, and having a diameter equal to or slightly greater than, the rotatable wheel, the cutaway portions corresponding to the "clear" regions and circumferential or rim portions forming the said engagement portions.

Although it is possible to employ only one support element, for many applications this will create problems of balance, and the use of two support elements is preferred. More than two may be provided, but this will not usually be necessary.

Preferably the or each support element is a "spider" having radially extending symmetrical arms each carrying a respective wheel. Four wheels are preferred.

Where there are two support elements, these may be rigidly secured to a common axle which is rotatably secured to the structure.

Preferably also the structure includes a handle for the person moving the load, for steering and guiding the load.

As previously mentioned, the invention may be applied to invalid chairs, and thus also provides a device of the type described above including a seat for receiving a patient.

Some embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 is a perspective view of of an invalid chair; Figs. 2a-c are schematic views illustrating the operation of the device; Fig. 3 is a view of the wheel assembly; Figs. 4 and 5 show the further wheel, and Fig. 6 is a sectioned view of one embodiment of invalid chair according to the present invention; Fig. 7 is a view similar to figure 6, showing the chair in use on a staircase; Fig. 8 is a front elevation of the arrangement shown in figure 7; and Fig. 9is a view similar to figure 7, showing another embodiment of the invention.

The invalid chair shown in Fig. 1 has a frame 1 of welded tubular steel construction with an integral handle 2. Frame members 3 carry a seat 4 for the patient, and a backrest 5 is also provided. The seat 4 may have hinged side members 6. Support elements 7 each in the form of a "spider" are secured one to each end of an axle (not visible in Fig. 1) mounted to the frame by means of bearings 8. Each spider 7 has four radially extending symmetrically disposed arms 9, and a wheel 10 is rotatably secured to the end of each arm. The chair also has one or more front wheels 11. When the chair is to be taken up or down a stepped path such as a staircase, the device proceeds downstairs (for example) as shown in Fig. 2, in the sequence a--bb--c-d. The sequence is, of course, reversed when proceeding upstairs.Fig. 2a envisages stairs or steps of a width such that two wheels can rest on the stair or steps simultaneously: this is not, however, essential to the operation of the device, and with relatively narrow stairs the spider can rotate from the position shown in Fig. 2c to that shown in Fig.

2b without the ieading wheel coming into contact with the stair.

A motor 12 (Fig. 1) may be provided to assist the ciimbing of stairs, the motor being arranged to rotate the axle upon which the spiders 7 are mounted. The motor drive may be by means of a free-wheel device to provide for automatic disengagement of the motor when travelling upstairs without power, whilst the motor drag provides a degree of damping when proceeding downstairs. Alternatively, or in addition, brakes, or damping means such as viscous damper (possibly with a free-wheel mechanism) may be provided to provide a degree of restraint during downstairs movement thereby relieving the person controlling the device of the need to support most of the weight of the load and thus reducing the risk of the device and load falling down the stairs in an uncontrolled and dangerous manner. Such measures are discussed in our copending U.K.

Patent Application No. 8207887.

However, restraining arrangements of this type, although serving to restrain rotation of the spiders 7, still permit free rotation of the wheels 10 which are freely mounted on the arms of the spiders. Thus the chair still has a relative freedom of movement down the staircase. In order to reduce this, the above mentioned application also describes an arrangement in which each wheel has, mounted alongside it, foot means in the form of a further wheel 13 of the same or possibly slightly greater diameter, as shown in Figs. 3, 4, and 5.

Each of these further wheels 13 is of generally circular shape, but has a pair of arcuate cut-away portions 14. As shown, the further wheel 13 consists of a steel dise 1 5 with a circumferential rim: The rim is omitted in the cut-away regions 14, and also has a gap to fit around the arm of the spider so as to leave three engagement portions 17, 18, 19. However, neither the form or construction nor the material of the further wheel is critical: in practice, a circumferential covering or type of rubber or other suitable material may be provided to prevent damage to floor coverings etc.

The further wheels 1 3 are rigidly secured to the.

spider 7, and the cut-out regions 14 are disposed in the manner indicated in Fig. 3: i.e. (for a fourarm spider) each cut-away portion is centred on a radius from the wheel lying at an angle of 450 to the spider arm on which the wheel is mounted. As a result, when the chair is on a level surface, or on a staircase with the spider in the position shown in Fig. 2a, the wheels 10 are in contact with the horizontal surface and the chair can move freely.

However, when the chair moves downward and forward to the position shown in Fig. 2b, the further wheel 13 on the trailing arm of the spider rotates along with the spider so that the leading engagement portion 1 7 of its circumference comes into contact with the stair and prevents further rolling on the wheel 10. Similarly, in the position shown in Fig. 2c, the central engagement portion 18 of the further wheel 13 again prevents rolling.

In the embodiment of the present invention shown in Figs. 6, 7 and 8, the motor 12 is not secured to the frame 1 of the chair but mounted on a bracket 23 pivotally mounted by bearings or bushes 24 on the axle 25. Drive from the motor 12 (which has an integral gearbox) is by means of a sprocket chain drive 26 to the axle 25. It will be appreciated that when the chair is travelling upstairs, the motor exerts an anti-clockwise torque (as viewed in Fig. 6) on the spider 7 and a corresponding clockwise torque on the motor mounting. If the motor is secured directly to the chair frame, this produces a tendency for the chair to tip in the downstairs direction, and this has to be countered by a corresponding force on the handle 2 by the person controlling the chair.In order to avoid this, the motor torque is restrained by means of a skid 27 integral with the bracket 23. When the chair is travelling on level ground, the motor not being in use, the skid is heid by means of a return spring 28 in the position shown in Fig. 6. When travelling upstairs, however, as shown in Fig. 7 the initial motor movement rotates the bracket 23 and skid 27 clockwise (as viewed in the drawing), against the action of the return spring 18 to the position shown in Fig. 7 until the skid bears against the staircase. Thus the necessary reaction force for the motor is provided by the contact between the skid and the staircase, and there is no tendency for the chair itself to tip.

The skid may be provided with a lead wheel 29.

Also, a manually lockable strut may be provided to secure the skid in position when not required.

When descending stairs, where the motor is being used for braking purposes, or where a brake or damper is mounted on the bracket with the motor, the skid provides a similar stabilising effect.

Figure 9 shows another embodiment of the present invention, where the motor (if fitted) is fixedly secured to the frame 1, the skid 27 serving to stabilise the entire chain The skid is again mounted on the axle 25, although this is not essential.

When the chair is travelling (or stationary) on a staircase, the skid 27 is locked in the position shown in solid lines in figure 9, and bears against the staircase, as shown, thus stabilising the entire assembly and preventing any tendency for the chair to tip downstairs if the person controlling the chair releases the handle 2. Indeed, the chair can be left unattended on the staircase, with comparative safety.

Movement of the skid 27 between its locked position and an upper, retracted position (shown dotted) is effected with the aid of a hinged strut 31. The upper portion 32 of the strut is pivotally secured by a pin 33 to an upright member 34 secured to the frame 1 (the upper end here is slightly cranked to clear the upright member 34), and its lower end is similarly secured to a bracket 35 on the skid 27. The central hinge 36 of the strut incorporates a coil spring (not shown) which urges the strut forward toward the locked, slightly over-centre position shown (further movement in this direction being prevented by abutments 37, 38 on the two portions of the strut).

The skid can be moved from its locked to its retracted position (shown dotted) by a handle 39 operating a Bowden cable 40 attached to the upper portion of the strut: pulling the handle upward moves the strut 31 to its retracted position shown dotted, when the handle can be latched by suitable means 41,42. Conversely, releasing the handle (when the chair has been moved onto the staircase) allows the skid to drop onto the stairs and the spring action moves the strut 31 into its over-centre position to lock the skid 27.

It will be appreciated that the angle at which the skid is locked in position must correspond substantially to that of the staircase, and thus the member 34 has a plurality of alternative holes 43 for receiving the pin 33; the appropriate hole being selected to suit the stair angle in question.

Claims (14)

Claims

1. A device for use in moving a load up or down a stepped path, comprising a structure for receiving the load, at least one support element rotatably mounted on the structure and having rotatably mounted thereon at least three symmetrically disposed wheels whereby, in use, the wheels cooperate with successive steps of the path, and an elongate forwardly extending stabilising element secured for pivotal movement between an upper, retracted position and a lower position in which, in use, it bears on the stepped path.

2. A device according to claim 1, in which means are provided to lock the stabilising element in its lower position.

3. A device according to claim 2, in which the locking means comprises a hinged strut connecting the stabilising element to the structure, movement of the hinge being limited in one direction whereby the strut is movable between a folded position in which the stabilising element is retracted and an over-centre position in which the stabilising element is locked in its lower position.

4. A device according to claim 3, in which the strut is spring-biased toward its over-centre position.

5. A device according to claim 1, including a motor arranged to drive the support element(s), the motor being pivotally mounted about an axis substantially coincident with that of the support element(s), and the stabilising element is secured for pivotal movement together with the motor.

6. A device according to any one of the preceding claims, further including foot means secured to each support element adjacent the corresponding wheel, the foot means being clear of the circumference of the wheel at two regions so that the wheel can roll freely on a plane when the support element is positioned with the wheel and respectively one or other of the adjacent wheels in contact with the plane, and having engagement portions located forwardly of the said two regions so as, when the support element is rotated forwardly of the said position, to engage the plane to prevent rolling movement.

7. A device according to claim 6, in which the clear regions are disposed symmetrically on each side of a radius of the support member passing through the axis of the associated wheel, one engagement portion lying on this radius and the other lying forwardly of the forwardmost of the two clear regions.

8. A device according to claim 7, in which a third engagement portion is provided, positioned rearwardly of the rearward clear regions.

9. A device according to claim 6, 7 or 8, in which each foot means comprises a further wheel non-rotatably mounted on the support member.

10. A device according to any one of the preceding claims, in which the or each support element is a spider having radially extending symmetrical arms each carrying a respective wheel.

11. A device according to any one of the preceding claims including a seat for receiving a patient.

12. A device for use in moving a load up or down a stepped path, substantially as hereinbefore described with reference to figures 6, 7 and 8 of the accompanying drawings.

13. A device for use in moving a load up or down a stepped path, substantially as hereinbefore described with reference to figure 9 of the accompanying drawings.

New Claims or Amendments to claims filed on 30 March 1983 New claim

14. A device according to any one of claims 1 to 11 in which the stabilising element is in the form of an elongate member arranged for sliding engagement with the stepped path during travel of the device.