GB2162143A

GB2162143A - A belt conveyor supported on an air cushion

Info

Publication number: GB2162143A
Application number: GB08419318A
Authority: GB
Inventors: Isaac Beresinsky
Original assignee: Simon Carves Ltd; Carves Simon Ltd
Current assignee: Simon Carves Ltd; Carves Simon Ltd
Priority date: 1984-07-28
Filing date: 1984-07-28
Publication date: 1986-01-29
Also published as: GB2162143B; GB8419318D0

Abstract

A belt conveyor of the "hover-belt" type in which a moving belt (10) passes over an air box (12) having apertures (14) in its upper surface through which a cushion of air is established to support the belt (10) includes breather tubes (15) at spaced locations along the air box (12) to permit excess air to escape to atmosphere to prevent lifting and distortion of the belt when lightly loaded. The breather tubes preferably comprise a tubular member open at both ends and passing through the air box. <IMAGE>

Description

SPECIFICATION A belt conveyor This invention concerns a belt conveyor of a type generally known as a "hover belt" conveyor wherein a travelling belt is supported on a cushion of air over a troughed and perforated upper surface of an air box which defines an enclosed chamber held at superatmospheric pressure. The effect of the cushion of air is to permit the belt to travel over the air box substantially free of frictional contact with the upper surface thereof.

Hoverbelt conveyors of this kind are well known and operate substantially trouble-free provided there is a continuous load of conveyed product on the belt.

If the belt is unloaded or lightly loaded for a period of time the air pressure beneath the belt tends to lift same in its longitudinal central region since it is in this region that an array of apertures in the upper troughed surface of the air box, is provided.

The build-up of pressure distorts the belt and can result in a deterioration in performance of the conveyor.

An object of the present invention is to provide a device in a belt conveyor of the aforementioned kind, which substantially prevents a build-up of pressure in zones where the belt is not adequately loaded in use.

According to the present invention there is provided a belt conveyor comprising an air box defin ing an enclosed chamber held at superatmospheric pressure and having a troughed and perforated up per surface over which a travelling belt passes and is supported by a cushion of air created by way of an array of apertures in said upper surface such that the belt is substantially free of frictional contact with said upper surface, characterised in that at least one breather tube connects said upper surface to atmosphere unless occluded and effectively sealed by the belt.

An embodiment of the invention will now be de scribed, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a plan view of a section of belt conveyor made in accordance with the invention; Figure 2 is a vertical section taken along line ll-ll of Fig. 1; and Figure 3 is an enlarged vertical section taken along line Ill-Ill of Fig. 1.

Referring now to the drawings, it will be seen that there is provided a belt 10 travelling in the di rection of arrow 11 over the surface of an air box generally indicated at 12.

In the upper surface 13 of the air box 12 there is a continuous array of perforations 14 which permit air at superatmospheric pressure to pass out of the air box thus to create a cushion of air upon which the belt 10 is supported through its length.

Typically, the width of the air box 12 is in the re gion of 1.2 metres, and at spaced positions along its length at a distance apart of approximately 5.5 metres, there are pairs of breather tubes 15 which pass through the air box 12 to connect the upper surface thereof to atmosphere. Each breather tube 15 has an upper flange 16 and is attached by backing nuts 17 to the underside of the air box.

The thickness of flange 16 is selected to be approximately equal to the depth of the air cushion created in use between the upper surface of the air box 12 and the under surface of the belt 10. In this way, when the belt is laden with conveyed product it rides with some frictional contact over the flanges 16 to prevent the air cushion from being diminished by escape of air through the breather tubes 15 to atmosphere. To ensure a smooth passage of the belt over the flanges 16, two opposed edges 16a thereof are chamfered as can be seen from Fig. 3.

In use, in the event that the belt 10 is unladen or only lightly laden with product, any tendency for the air cushion to lift the belt to any appreciable height above the upper surface 13 of the air box will permit air to escape to atmosphere through the breather tubes 15 so that the belt 10 will settle down once again.

Thus there is provided a simple expedient to ensure that the air cushion is maintained but that it is not permitted to distort the belt under any operating conditions.

The internal diameter of the breather tubes 15 is typically in the region of 50mm but the dimensions and proximity of the tubes may be selected according to the dimensions and operating perameters of the conveyor.

Breather tubes, in accordance with the invention, can be readily introduced into existing hover-belt conveyors either by drilling the upper and lower surfaces of the air box to receive the breather tubes, or by placing prefabricated box sections including the breather tubes, at spaced positions along the length of the conveyor.

1. A belt conveyor comprising an air box defining an enclosed chamber held at superatmospheric pressure and having a troughed and perforated upper surface over which a travelling belt passes and is supported by a cushion of air established between the upper surface of the air box and the lower surface of the belt, by way of an array of apertures in said upper surface such that the belt is substantially free of frictional contact with said supper surface, characterised in that at least one breather tube connects said upper surface to atmosphere unless occluded and effectively sealed by the belt.

2. A belt conveyor according to Claim 1, wherein said at least one breather tube comprises a tubular member open at both ends and passing through the air box so as to communicate with the upper surface thereof and with atmosphere beneath the box.

3. A belt conveyor according to Claim 1 to Claim 2, in which said at least one breather tube is connected to a flange which rests on the upper surface of said air box and has a thickness which is selected to be approximately equal to the depth of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A belt conveyor This invention concerns a belt conveyor of a type generally known as a "hover belt" conveyor wherein a travelling belt is supported on a cushion of air over a troughed and perforated upper surface of an air box which defines an enclosed chamber held at superatmospheric pressure. The effect of the cushion of air is to permit the belt to travel over the air box substantially free of frictional contact with the upper surface thereof. Hoverbelt conveyors of this kind are well known and operate substantially trouble-free provided there is a continuous load of conveyed product on the belt. If the belt is unloaded or lightly loaded for a period of time the air pressure beneath the belt tends to lift same in its longitudinal central region since it is in this region that an array of apertures in the upper troughed surface of the air box, is provided. The build-up of pressure distorts the belt and can result in a deterioration in performance of the conveyor. An object of the present invention is to provide a device in a belt conveyor of the aforementioned kind, which substantially prevents a build-up of pressure in zones where the belt is not adequately loaded in use. According to the present invention there is provided a belt conveyor comprising an air box defin ing an enclosed chamber held at superatmospheric pressure and having a troughed and perforated up per surface over which a travelling belt passes and is supported by a cushion of air created by way of an array of apertures in said upper surface such that the belt is substantially free of frictional contact with said upper surface, characterised in that at least one breather tube connects said upper surface to atmosphere unless occluded and effectively sealed by the belt. An embodiment of the invention will now be de scribed, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a plan view of a section of belt conveyor made in accordance with the invention; Figure 2 is a vertical section taken along line ll-ll of Fig. 1; and Figure 3 is an enlarged vertical section taken along line Ill-Ill of Fig. 1. Referring now to the drawings, it will be seen that there is provided a belt 10 travelling in the di rection of arrow 11 over the surface of an air box generally indicated at 12. In the upper surface 13 of the air box 12 there is a continuous array of perforations 14 which permit air at superatmospheric pressure to pass out of the air box thus to create a cushion of air upon which the belt 10 is supported through its length. Typically, the width of the air box 12 is in the re gion of 1.2 metres, and at spaced positions along its length at a distance apart of approximately 5.5 metres, there are pairs of breather tubes 15 which pass through the air box 12 to connect the upper surface thereof to atmosphere. Each breather tube 15 has an upper flange 16 and is attached by backing nuts 17 to the underside of the air box. The thickness of flange 16 is selected to be approximately equal to the depth of the air cushion created in use between the upper surface of the air box 12 and the under surface of the belt 10. In this way, when the belt is laden with conveyed product it rides with some frictional contact over the flanges 16 to prevent the air cushion from being diminished by escape of air through the breather tubes 15 to atmosphere. To ensure a smooth passage of the belt over the flanges 16, two opposed edges 16a thereof are chamfered as can be seen from Fig. 3. In use, in the event that the belt 10 is unladen or only lightly laden with product, any tendency for the air cushion to lift the belt to any appreciable height above the upper surface 13 of the air box will permit air to escape to atmosphere through the breather tubes 15 so that the belt 10 will settle down once again. Thus there is provided a simple expedient to ensure that the air cushion is maintained but that it is not permitted to distort the belt under any operating conditions. The internal diameter of the breather tubes 15 is typically in the region of 50mm but the dimensions and proximity of the tubes may be selected according to the dimensions and operating perameters of the conveyor. Breather tubes, in accordance with the invention, can be readily introduced into existing hover-belt conveyors either by drilling the upper and lower surfaces of the air box to receive the breather tubes, or by placing prefabricated box sections including the breather tubes, at spaced positions along the length of the conveyor. CLAIMS

3. A belt conveyor according to Claim 1 to Claim 2, in which said at least one breather tube is connected to a flange which rests on the upper surface of said air box and has a thickness which is selected to be approximately equal to the depth of said air cushion.

4. A belt conveyor according to Claim 3, in which said flange has two opposed chamfered edges to ensure a smooth passage of the belt over the flange.

5. A belt conveyor according to any preceding claim, including a plurality of said breather tubes arranged in pairs at spaced locations along the working length of the conveyor.

6. A belt conveyor according to any preceding claim, wherein a pair of breather tubes is provided in a prefabricated box section placed at one or a number of positions along the length of the conveyor.

7. A belt conveyor substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.