GB2231014A

GB2231014A - Vehicle steering arrangement

Info

Publication number: GB2231014A
Application number: GB9008572A
Authority: GB
Inventors: Guthrie David Boath
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-04-14
Filing date: 1990-04-17
Publication date: 1990-11-07
Also published as: GB9008572D0; GB8908511D0

Abstract

A steerable vehicle such as a wheelchair comprising a frame (6) having a plurality of ground engaging wheels, there being at least two steerable (2, 4) and two freely-pivotable wheels (8, 10). The steerable wheels being located at non- adjacent points on a polygon, thus enabling the vehicle to be manoeuvred in straight lines in any direction even in confined spaces. The steerable wheels (2, 4) can be connected by a chain and cog wheels. An indicator system such as coloured lights can be provided for indicating the direction of rotation of the wheels. <IMAGE>

Description

"Steerable Vehicle" This invention relates to a steerable vehicle.

Conventional steerable vehicles generally have steerable wheels disposed side-by-side at the front, or at the rear, of the vehicle, with fixed wheels at the opposite end. Either the steerable wheels or the fixed wheels may be driven. While this arrangement generally proves easy to control, it does restrict the manoeuvrability of the vehicle, as changes of direction entail movement of the vehicle in a curve across the ground; sideways or angular movement in a straight line is not possible, and the vehicle cannot be rotated without forward or rearward movement.

According to the present invention there is provided a steerable vehicle comprising a body on which ground-engaging wheels are disposed, at least two of the wheels being steerable and being driven, the remaining wheels being freely pivotable, wherein the wheels are disposed on the body so as to engage the ground at the points of a polygon with steerable wheels being disposed at non-adjacent points of the polygon.

A polygon in this context is intended to mean any plain figure bounded by three or more straight lines.

Preferably the steerable wheels are interconnected so as to be steerable in unison.

Most preferably, the interconnector is a chain which is driven by cog wheels.

Preferably also the vehicle has a pair of steerable wheels disposed at opposite points of a quadrilateral, most preferably a rectangle or square, with a pair of freely pivotable wheels disposed at the other points.

The vehicle may be remote-controlled or controlled by an operator travelling on it. If remote-controlled, an indicator system may be provided between the vehicle and the control apparatus to facilitate identification of the direction of movement of the vehicle; for example a system of coloured lights disposed at positions on the vehicle and corresponding to a colour code on the control apparatus can give a clear indication of the appropriate movement of the vehicle in response to a control command.

Preferably, the vehicle is powered by an electric motor.

Accessories may be provided on the vehicle for performing tasks, for example gripper jaws which may be provided with resilient belts for engaging items to be gripped1 in order to provide gentle engagement.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is an underneath plan view of a vehicle of the present invention showing the arrangement of the wheels; Fig. 2 is a top plan view of the base member of the vehicle of Fig. 1; Fig. 3 is a side view of the direction indicator system of the vehicle of Fig. 1; Fig. 4 is a side view of part of the steering system of the vehicle of Fig. 1; and Fig. 5 is a plan view of a control system for gripper jaws for use on the vehicle.

Referring to the drawings, the vehicle of this embodiment is a remote-control unit for use by disabled people in fetching and carrying items, for example in the home where space is restricted. Fig. 1 shows the wheel layout wherein two drive wheels 2, 4 are mounted on a body 6 in the form of a frame or chassis, the wheels 2,4 being disposed at opposite corners of a notional square. At the alternate corners of the square are mounted freely - pivotable castor wheels 8, 10.

The drive wheels 2, 4 are steerable in unison by means of the mechanism shown in Fig. 2, in which a pivotal axis pin connected to the wheel 2 carries a cog 14 around which a continuous chain 16 passes. The chain 16 extends around two cog wheels 18, 20 at the corner above the castor wheel 8, and thence around a further cog 22 on a pivotal axis pin connected to the wheel 4.

A chain tensioner 24 is provided at the cog wheel 20.

In Figs. 3 and 4, the drive wheel 2 is mounted on a drive shaft 26 extending from an electric motor 28 secured to a bracket 30 and thence through a ball bearing 32 to the body 6, so that the wheel 2, motor 28 and bracket 30 are pivotal on the body 6 as a unit.

This unit is pivoted by a steer motor 34 connected to the cog wheel 18 as shown in Fig. 4 through a gear box 36. actuating of the steer motor 34 therefore provides pivoting of the wheel 2 and corresponding pivoting of the diagonally opposed wheel 4, by means of the chain 16.

The steer motor 34 and the drive motors 28 (one on each of wheels 2, 4) are controlled and actuated electronically through micro-switches 37.

In Fig. 3, a pulley drive 38 is mounted above the drive wheel 4 so as to pivot with the wheel 4. The pulley cord 44 passes around pulley wheels 40, 42 to a second pulley drive 46 on which a direction indicator 48 is mounted. The indicator 48 pivots with the wheel 4 and is disposed on top of the vehicle so as to be easily visible. A return spring 50 allows counter-rotation of the indicator 48 on opposite pivoting of the wheel 4 and maintains the cord 44 taut. The indicator has a series of lamps of different colours corresponding to a colour coding on a remote control unit, the lamps illuminating in accordance with the attitude of the vehicle and its control mode so as to facilitate the anticipation of its movement on actuation.

In Fig. 5, gripper jaws 52 are shown, and these are secured on the body of the vehicle to grip, release and manipulate items for the operator. The jaws 52 are operated by a hydraulic system pressurised by an electric motor 56 through a pump 58, with return springs 60, 62 biassing the jaws 52 open.

The jaws 52 each comprise a generally semi-circular arm 64 across the ends of which is stretched a rubber band 66, and the jaws 52 are each hinged to a support member at 68. The rubber bands 66 allow items to be gripped without undue pressure being exerted on the items.

In use, the vehicle can be moved in any direction in a straight line by actuating the drive motors 28 at an identical speed while steering in the desired uniform direction. Alternatively, the vehicle can move in a curve by actuating the steer motor 34, or can pivot about an axis by differential actuation of the drive motors 28. The vehicle can thus be pointed in any desired direction, and moved in any desired direction, in a restricted space.

While this embodiment of the invention is specifically designed for use by the disabled, the invention can also apply to industrial use, for example on fork-lift trucks or other cargo handling equipment, and to normal vehicular use.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

1. A steerable vehicle comprising a body on which ground-engaging wheels are disposed, at least two of the wheels being steerable and being driven, the remaining wheels being freely pivotable, wherein the wheels are disposed on the body so as to engage the ground at the points of a polygon with steerable wheels being disposed at non-adjacent points of the polygon.

2. A steerable vehicle as claimed in Claim 1, wherein the steerable wheels are interconnected so as to be steerable in unison.

3. A steerable vehicle as claimed in Claim 2, wherein the interconnector is in the form of a chain which is driven by cog wheels.

4. A steerable vehicle as claimed in any preceding Claim, wherein the vehicle comprises a pair of steerable wheels disposed at opposite points of a quadrilateral.

5. A steerable vehicle as claimed in Claim 4, wherein the quadrilateral is a rectangle or square.

6. A steerable vehicle as claimed in any preceding Claim, wherein the vehicle is remote-controlled.

7. A steerable vehicle as claimed in any of Claims 1 to 5, wherein the vehicle is controlled by an operator travelling on it.

8. A steerable vehicle as claimed in Claim 6, wherein an indicator system is provided between the vehicle and the control apparatus to facilitate identification of the direction of movement of the vehicle.

9. A steerable vehicle as claimed in Claim 8, wherein the indicator system comprises a system of coloured lights disposed at positions on the vehicle and corresponding to a colour code on a control apparatus which provides a clear indication of the appropriate movement of the vehicle in response to a control command.

10. A steerable vehicle as claimed in any preceding Claim, wherein the vehicle is provided with accessories which are capable of performing tasks.

11. A steerable vehicle as claimed in Claim 10, wherein the accessories are in the form of gripper jaws provided with resilient belts for engaging items to be gripped.

12. A steerable vehicle as claimed in any preceding Claims, which is powered by an electric motor.

13. A steerable vehicle substantially as hereinbefore described with reference to the accompanying drawings.