GB2328193A

GB2328193A - Variable speed conveyor

Info

Publication number: GB2328193A
Application number: GB9714371A
Authority: GB
Inventors: Michael Pattision
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-07-09
Filing date: 1997-07-09
Publication date: 1999-02-17
Also published as: GB9714371D0

Abstract

A variable speed conveyor, particularly useful for conveying pedestrians, comprises interfitting elements 52 forming a load surface, which elements 52 are supported and driven by carrier rods 12. The rods 12 are in turn driven by a pair of drive shafts 20 having a scroll whose pitch varies along the length of the shafts. The load surface can expand and contract as the speed of the rods 12 and elements 52 changes with the changing pitch of the scrolls 20. The conveyor may be curved by the scrolls 20 on different sides of the conveyor having different scroll pitches so that one side of the conveyor is driven faster than the other to cause the conveyor to follow a curved path. The elements 52 may be made of flexible material to allow them to flex as the conveyor path curves. A number of different conveyors may be combined to allow choices of destination by changing from one conveyor to others.

Description

VARIABLE SPEED CONVEYOR.

This invention is concerned with a variable speed conveyor which is primarily intended for use as a pedestrian conveyor or walkway but which can also be used as a conveyor for transporting goods.

Pedestrian walkways are an increasingly popular method of transporting people in, for example, airport terminal buildings where passengers are often tired, are carrying considerable quantities of hand luggage and have to go considerable distances between the airport lounges and the arrival/departure gate. The walkways provide a method of moving large numbers of passengers in an orderly way with minimal effort on the part of the passengers.

However, walkways do suffer from the disadvantage that they are too slow as they move at little more than walking pace.

This is quite simply because walkways move at a constant speed throughout their length and the limiting speed is that at which a person, who may be elderly, can safely step onto the walkway. This disadvantage limits the places in which walkways can be used with advantage.

It is an object of the present invention to obviate or mitigate this disadvantage.

The present invention is a conveyor comprising an elongate surface movable in a longitudinal direction and formed of interfitting surface members which are movable in said direction relative to adjacent surface members, carrier rods engaging the surface members and extending at right angles to said direction beneath the surface members to support the members, and drive means for moving the rods and thus the members in said direction, the rods being movable at a first speed in one region of the conveyor and at a second speed in a second region.

The present invention is also a conveyer system comprising a plurality of conveyors as defined in the last preceding paragraph, changeover places being provided between two conveyors at which the speed differential between the conveyors is within a safe limit.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig.l is a side sectional elevation showing details of a drive system used with embodiments of the present invention; Fig.2 is a cross-sectional elevation of the drive system of Fig.l; Fig.3 is a side view of a drive member used in this embodiment of a conveyor according to the present invention; Fig.4 is a diagrammatic illustration of support rods lying across a pair of the drive members of Fig.3; Fig.5a is a side view showing the engagement of the support rods with surface members of the conveyor; Figs.5b and 5c are plan views showing the surface members and support rods in extended and compressed configurations respectively; and Figs.6 and 7 illustrate conveyor systems using conveyors according to the present invention.

Referring now to Figs.l and 2 of the drawings, a conveyor according to the present invention has an elongate load surface 10 supported for movement in its longitudinal direction on carrier rods 12. The rods 12 extend across conveyor beneath the surface 10 and have wheels 14 at each end, the wheels running in tracks 16 at the sides of the surface 10. The rods 12 are engaged, in this embodiment of the invention, by two different drive means, the first of which includes a pair of drive members 20 each in the form of a drive shaft having on its periphery a thread or scroll 22, as seen best in Fig.3. The drive shafts 20 extend in the longitudinal direction and are driven synchronously by an electric motor 24. The second drive means includes a chain conveyor drive 26 driven through gearing 28 by the motor 24.

Handles 34 are provided at the sides of the conveyor for the use of people on the load surface 10, the handles 24 being driven at the same speed as the adjacent load surface 10 by a motor 36 through an auxiliary drive shaft 30 having a scroll in engagement with the handles 34, the scroll on the auxiliary shaft 30 matching the scrolls on the drive shafts 20.

The scrolls 22, and the matching scrolls engaging the handles 26, do not have a uniform pitch throughout their length but rather have a first section 38 in which the pitch is relatively small, an intermediate section 40 in which the pitch progressively increases and a final section 42 in which the pitch is relatively large. As the drive shafts 20 are rotated at constant speeds the speed of the carrier rods 12 engaged by the scrolls 22 is directly related to the pitch of the scrolls and is relatively low in the first section 38, increases in the intermediate section 40 and is relatively fast in the final section 42, the carrier rods being driven from left to right as seen in Fig.4.

Clearly, as shown in Fig.4, the spacing between adjacent carrier rods 12 matches the pitch of the scrolls 22 and this implies that the load surface 10 can expand and contract longitudinally to allow for the variable spacing between the rods 12. This variable spacing is achieved by forming the load surface 10 as a succession of alternate interfitting members 50a and 50b, each member being comprised of a number of longitudinal slats 52 which have depending projections 54 at their forward ends in engagement with one of the transverse carrier rods 12 while their rear ends rest on the following carrier rod 12. Thus the slats 52 of the first member 50a engage one rod 12 and rest on the next following rod 12 while the slats 52 of the second member 50b engage the next following rod 12 and rest on the next rod that follows. A spacer bar 56 interconnects the leading ends of the slats of each of the members 50a or 50b and passes through a slot 58 in the slats of the next successive member 50b or 50a.

The drive shaft 20 shown in Fig.3 is one of the pair provided at the start of a conveyor and accelerates the load surface 10 from the low safe initial speed to a higher transport speed. At the end of the conveyor is provided a pair of drive shafts which reverse this process and decelerate the load surface 10 from the transport speed to a speed at which it is safe to step off the conveyor. Clearly, in many situations in which the conveyor is used the regions in which the initial acceleration and final deceleration take place are short in comparison with the overall length of the conveyor, and it is preferred to use a different drive system in the main length of the conveyor where there is a constant speed. This different drive system is, in this embodiment, the chain conveyor drive 26 of Figs.1 and 2 which overlaps the ends of the drive shafts 20 and has projections 60 which engage the carrier rods 12.

As the ratio of the maximum and minimum speeds of the conveyor is determined by the maximum and minimum spacing of the carrier rods it may be that in some cases it is not be possible to achieve a desired maximum speed. This problem can be overcome by providing two or more conveyors running side by side at different speeds. The speed differential between adjacent conveyors would be kept to below the maximum safe value and access to a faster conveyor would be possible only from a conveyor having a safe speed differential.

As so far described the invention has been described in relation to straight flights of conveyors, but as illustrated in Fig.6 it is possible to have conveyors that are gently curved. If the scrolls 22 on different sides of the conveyor have uniform but different scroll pitches then one side of the conveyor will be driven faster than the other and then, if the load surface 10 can take up or absorb the distortions in the surface members 50a and 50b that this brings about, the conveyor can follow a curved path. For this reason the slats 52 are made of a high tensile flexible material (carbon fibre in this embodiment) which allows the members 50a and 50b to flex as the conveyor path curves.

In this way a complex pattern of conveyors can be formed as illustrated in Fig.7 where a number of different conveyors 70, 72, 74, 76, 78 and 80 are combined to allow choices of destination by changing from one conveyor to others, the only caveat being that a safe speed differential must be maintained between adjacent conveyors at the changeover points where two conveyors run alongside each other.

Claims

1. A conveyor comprising an elongate surface movable in a longitudinal direction and formed of interfitting surface members which are movable in said direction relative to adjacent surface members, carrier rods engaging the surface members and extending at right angles to said direction beneath the surface members to support the members, and drive means for moving the rods and thus the members in said direction, the rods being movable at a first speed in one region of the conveyor and at a second speed in a second region.

2. A conveyor as claimed in claim 1, in which the drive means includes a pair of drive shafts having scrolls on their surface, the pitch of the scrolls being different in first and second regions of the scrolls.

3. A conveyor as claimed in claim 2, in which the scrolls engage the carrier rods.

4. A conveyor as claimed in any preceding claim, in which each surface member comprises longitudinal slats engaging a carrier rod at one of their ends to be driven thereby, and resting on an adjacent carrier rod at their other ends, the slats of each member interfitting with the slats of the preceding and following members.

5. A conveyor as claimed in claim 4, in which the slats engage a carrier rod at their forward ends.

6. A conveyor as claimed in claim 4 or claim 5, in which the slats of each member are interconnected by a spacer bar.

7. A conveyor as claimed in claim 6, in which the slats are provided with a slot in which the spacer bar of an adjacent member can move.

8. A conveyor as claimed in any of claims 4 to 7, in which the slats are made of a flexible material.

9. A conveyor as claimed in any of claims 4 to 8, in which the slats are made of a high tensile material.

10. A conveyor as claimed in claim 2 or any of claims 3 to 9 when dependent on claim 2, in which a first pair of drive shafts is provided at the start of the conveyor to accelerate the surface of the conveyor, and a second pair of drive shafts is provided at the end of the conveyor to decelerate the surface of the conveyor.

11. A conveyor as claimed in claim 11, in which at least one chain conveyor drive is provided between the pairs of drive shafts.

12. A conveyor as claimed in any preceding claim, in which handles are provided at the side of the conveyor, the handles being driven by a scroll on an auxiliary drive shaft at the same speed as the adjacent region of the surface.

13. A conveyor as claimed in any preceding claim, in which there are regions of the conveyor in which the two sides of the conveyor are driven at different speeds.

14. A conveyor as claimed in claim 13 when dependent on claim 2, in which the scrolls on the two drive shafts of a pair are different to cause a speed differential between the sides of the carrier rods and allow the conveyor to follow a curved path.

15. A conveyor substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

16. A conveyer system comprising a plurality of conveyors as claimed in any preceding claim, changeover places being provided between two conveyors at which the speed differential between the conveyors is within a safe limit.