GB2069432A

GB2069432A - Conveying systems with individually steerable wheels

Info

Publication number: GB2069432A
Application number: GB8104654A
Authority: GB
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1980-02-15
Filing date: 1981-02-13
Publication date: 1981-08-26
Also published as: DE3005685A1; FR2475998A1; DE3005685C2; FR2475998B1; GB2069432B; IT8119706A1; IT8119706A0; IT1169050B

Abstract

A guide rail 11 serves to guide a vehicle 1, steerable wheels 3 of which are coupled by a mast 7 to a trolley supported on the rail. Lateral movements of the trolley as it negotiates curves in the rail serve to steer the wheels to cause it to follow the direction of the mast. Electric current is supplied to drive motors 14 from live rails carried by the guide rail by way of collector shoes supported on the trolley. <IMAGE>

Description

SPECIFICATION Improvements in conveying systems A conveying system is known which includes a plurality of individually powered, steerable vehicles. A conventional type of vehicle used in such a system is powered by one or more electric motors supplied with electricity from a battery pack carried on the vehicle. The size of the battery pack needed makes the vehicle very heavy and expensive. The vehicle is controlled by an operator who travels with it and this requirement increases the operating cost. It has been proposed to control such a vehicle using an induction line embedded in the floor, and to haul a similar unpowered vehicle, using a haulage chain, travelling in a slot in the floor.Disadvantages of these latter systems are that it is necessary to interfere with the floor of the workshop or factory in which the conveying system operates, and to provide open slots in the floor if a haulage chain is used.

To avoid the problems encountered with the known systems, it is proposed herein that the vehicle of such a conveying system should be powered by one or more electric motors receiving electric current from conductors arranged overhead and extending along a guide rail. The vehicle is connected to a current collector trolley, supported on the guide rail and provided with collector shoes connected with the motor or motors by way of leads. The trolley is coupled with the vehicle by means of a coupling element and changes in direction of the trolley as it travels along the guide rail are used to transmit steering movements to a steerable wheel, or to steerable wheels, of the vehicle. The trolley is thus propelled along the guide rail by the vehicle which is steered to follow the direction of the guide rail.

Consequently, it is unnecessary for the vehicle to be accompanied by an operator, or for it to be equipped with batteries, or for the shop floor to be slotted or have any guidance equipment embedded therein, thereby avoiding the problems associated with all the prior discussed.

Conveniently, the axle of the or each steerable wheel is carried by a pivotal wheel mounting from which extends a rigid shaft to which the coupling element may be located forwardly or rearwardly of the pivot axis. In the event that the vehicle has more than one steerable wheel, a wheel mounting common to all wheels is preferred, although individually pivoted wheels may be employed.

The track width of the steerable wheels of a vehicle having more than one steerable wheel is preferably less than that of the non-steerable wheels, in order to avoid the steering of the vehicle being adversely affected by differences in the rolling resistances of the steerable wheels. By a suitable choice of relative dimensions, the stability of the vehicle need not be unacceptably affected by this construction.

Preferably, the drive is transmitted to the steerable wheel or wheels, and in the case of a vehicle having more than one steerable wheel, each such wheel may be connected with a respective motor. The electric motors desirably have corresponding motor characteristics, to permit differences in rotational speeds of the steerable wheels during cornering, and avoid slip of the wheels on the floor. The electrical supply conductors of the motor or motors are conveniently led along the coupling element from the collector shoes, internally or externally on the coupling element.

The coupling element may be connected with the trolley by a guide arrangement which permits relative rotation between the trolley in a vertical direction relative to the vehicle in order to accommodate variations in height of the guide rails. The coupling element is conveniently in the form of a tube of circular cross-section received and guided in rollers disposed forwardly, rearwardly and laterally of the tube, the rollers being journalled about horizontal axes in bearing blocks projecting downwardly from the trolley.

Alternatively, to permit the accommodation of greater variations in height of the guide rail, the tube may be telescopically connected with a tube projecting downwardly from the trolley.

In the drawing: Figure 1 shows a first construction of a vehicle and a current collector trolley associated with a guide rail.

Figure 2 is a plan view of a vehicle, omitting the trolley.

Figure 3 shows a modification.

Referring to Figures 1 and 2, a conveying system includes an overhead guide rail 11 extending through a workshop or factory above the path to be followed by a plurality of identical vehicles 1, a single one of which is shown in the drawing and will now be described. The vehicle has a chassis with a flat load carrying surface, supported on a rearward pair of non-steerable wheels 2, and a forward pair of steerable wheels 3, journalled so as to rotate freely on axles supported by a common wheel support mounting pivoted about a vertical axis in a pivot bearing 5.

The track width of the non-steerable wheels is greater than that of the steerable wheels. Each of the steerable wheels is driven individually from a respective electric motor 1 4 by way of a simple transmission arranged laterally of the wheel.

The vehicle is associated with a trolley 10, having a support roller rotating about a horizontal axis and running on an upper support surface of the guide rail, and a pair of parallel counter-rollers running on the under-surface of the rail. Each of these rollers is adjacent to a pair of guide rollers which rotate about vertical axes. Each guide roller engages a respective lateral guide surface of the rail so that the trolley is constrained to follow the rail. The web portion of the rail 11 is provided on one or each side with a plurality of conductor rails or lines 12, from which electric current may be tapped by sliding collector shoes carried by a current collector assembly 1 3 supported on the trolley.

The trolley is linked with the vehicle by a coupling element in the form of a mast constituted by vertical tube 7 connected rigidly to a shaft 6 projecting horizontally forwardly from the wheel mounting. The upper end of the tube is guided for rotational and vertical movement relative to the trolley in a guide arrangement including a group of equi-angularly spaced bearing blocks 9, in each of which a guide roller 8 is journalled for rotation about a horizontal axis, such that the rollers are disposed in a cruciform arrangement, forwardly rearwardly, and to both lateral sides of the tube 7.

Limited movement of the tube relative to the guide block may thus take place to accommodate variations in height of the rail and during cornering. Of course, bearings other than rollers may be employed for this purpose.

In the modification shown in Figure 3, the tube 7 is received teiescopically within an elongate tube 1 5 pivoted to the trolley and depending therefrom. The tube 1 5 is provided with two vertically spaced groups of rollers 8 to permit relative vertical and rotational movement to take place between the tubes 7 and 15.

Current conductors 1 6 extend from the collector shoes internally (or in a modification, externally) of the tube 7 (and tube 8 in Figure 3) and are connected to the motors 14 directly, or by way of switching or automatic control equipment.

In operation, the motors 14 propel the vehicle which pushes the trolley 10 ahead of the steerable wheels 3. As the trolley negotiates changes in direction of the guide rail 11, the coupling element is displaced to one side or the other, causing the wheel mounting to turn and steer the vehicle. By arranging for the motors to have suitable operating characteristics, slipping of the wheels is avoided during cornering.

Changes may be made to this construction.

Thus, there may be a single steerable wheel journalled in a fork-shaped mounting. Instead of powering the steerable wheels, the non-steerable wheels (or a single non-steerable wheel) may be powered. Instead of using a direct mechanical linkage from the trolley to the steering system, an indirect mechanical or other system may be used.

The shaft 6 may project rearwardly from the wheel mounting, rather than forwardly therefrom.

Claims

1. A conveying system comprising an electrically driven vehicle having one or more steerable wheels, in combination with a guide rail spaced above the floor upon which the vehicle travels, current supply conductors extending parallel to the guide rail; wherein the vehicle is associated with a current collector trolley supported by and movable along the guide rail, the trolley being provided with means for tapping electricity from the current supply conductors and supplying the electricity to electric drive means of the vehicle, and wherein the trolley is connected to the vehicle by a coupling element arranged to steer the steerable wheels of the vehicle to follow the direction of the guide rail.

2. A conveying system according to Claim 1, wherein the coupling element of the vehicle extends substantially vertically and is connected to a shaft projecting from a wheel mounting of the vehicle, forwardly or rearwardly of a pivot axis of the wheel mounting.

3. A conveying system according to Claim 2, wherein two steerable wheels of the vehicle are supported by said wheel mounting for movement about a common axis.

4. A conveying system according to Claim 3, wherein the track width of the steerable wheels of the vehicle is less than that of the non-steerable wheels.

5. A conveying system according to Claim 3 or Claim 4, wherein each steerable wheel of the vehicle is drivably connected with a respective electric motor.

6. A conveying system according to Claim 5, wherein the motors of the vehicle have corresponding smooth motor characteristics.

7. A conveying system according to any preceding Claim, wherein leads for carrying electricity from the trolley to the vehicle pass along the coupling element, internally or externally thereof.

8. A conveying system according to any preceding Claim, wherein the coupling element is connected with the trolley by means of a guide permitting rotational and vertical movement of the trolley relative to the coupling element.

9. A conveying system according to Claim 8, wherein the guide comprises a plurality of rollers having horizontal axes, the rollers being disposed in surrounding relationship with the coupling element.

10. A conveying system according to Claim 8, wherein the guide is in the form of a tube articulated to the trolley and receiving telescopically the coupling element.

11. A conveying system according to any preceding Claims, including a plurality of identical such vehicles.

12. A vehicle comprising a chassis supported on a plurality of wheels, at least one of which is steerable and supported in a wheel mounting pivotal about a substantially vertical axis, a mast extending vertically from the mounting at a position spaced from its axis of rotation, means at the upper end of the mast adapted to follow a guide rail, whereby force applied laterally to the mast apply steering movements to the wheel mounting, collector shoes for collecting current from conductor rails associated with the guide rail, and electrical conductors for connecting said shoes with at least one electric motor for propelling the vehicle.

13. A vehicle substantially as hereinbefore described with a reference to and as illustrated in the drawing.

14. A conveying system comprising a guide rail, conductor rails supported thereby, and a plurality of vehicles as claimed in Claim 13.