GB2170464A - Conveyor apparatus - Google Patents

Abstract

Conveyor apparatus for use, e.g. in a silo, comprises a solid or rigid base (8) with solid or rigid upright walls (11) arranged side by side with suitable spacings between them. Across the tops of these solid or rigid walls is fixed a flexible membrane (12) which flexes up or down in relation to the tops of the walls depending upon the pressure within the air chamber defined between the upright walls and beneath the flexible membrane. When the membrane is drawn down between the solid or rigid walls, any material above the membrane is caused to fall into the depression and when it is pushed upwards any material thereon is caused to fall from this new position. In flexing the membrane in a sequential manner from chamber to chamber at a suitable cadence a conveying action is achieved. <IMAGE>

Description

SPECIFICATION Conveyor apparatus This invention relates to conveyor apparatus applicable to the conveying or shifting of, for example, bulk materials, produce and liquids. The invention has particular, but not exclusive, reference to the shifting of grain from the interior to the exterior of a silo.

The present invention provides conveyor apparatus using a solid or rigid base with upright walls equally spaced, across the tops of which is fixed a flexible membrane which flexes positively and negatively in relation to the tops of the upright walls depending upon the pressure within the chambers between the upright walls and beneath the flexible membranes (Figure 3 No. 14).

Advantageously, the upright walls of the solid base are arcuate and generally parallel as shown in plan.

Preferably the membrane will be made to flex positively and negatively by the introduction or exhaustion of a fluid, being a positive pressure for the inflation, and a negative pressure for the deflation. Air seems a useful fluid but any fluid could be selected depending upon the local conditions.

Polyurethane is a particularly suitable elastomeric material but rubber may be used instead.

The importance of using a solid or rigid base with upright members is to be able to allow the flexible membrane to descend beneath the apex of the upright members, allowing the grain, or whatever is being conveyed, to fall in to the depression formed by the evacuation of the fluid from the chamber (14) beneath the membrane and between the upright members.

The actual section of the upright members is variable but are shown triangular in Figure 3, but could equally be semicircular.

The construction of the solid or rigid base may be as shown in Figure 3 but variations are of course possible and will depend upon experience with the particular material to be conveyed.

Advantageously the flexible membranes will be attached to the tops of the rigid walls, as shown in Figure 3, by integrally formed strips, 13, adhesively attached to the walls. The flexible membranes can also be attached on both sides of the walls by having two intergrallyformed strips 13.

The chambers 14 are closed off at the ends of the walls 11 by end sealing walls (not shown) but each chamber 14 communicable with its associated service tube (10) by means of a series of holes (15) in the upper wall of the tubes (10).

If a particular one of the tubes 10 is connected to a supply of air under pressure, the air passes through the holes (15) of that tube and causes the part of the elastomeric sheet (12) forming a wall of the associated chambers (14) to be elastically deformed and bulge outwardly. Conversely, if suction is applied to a particular one of the tubes (10) the associated part of the elastomeric sheet (12) is drawn down into the space between the associated upright members.

Advantageously the flexible membrane will be fixed to the tops of the walls in such a way that after fixing the membranes will be level and by its elastic nature will by and maintain this neutral position.

This elastic force will provide a desire for the membrane to return to this neutral position during and afterthe deformation of the membrane by the changing of the pressure within the chamber (14) and this desire will contribute to the operation of the conveyor.

A silo provided with conveyor apparatus constructed in accordance with the invention will now be described by way of example only with reference to the accompanying drawings in which Figures 1 is a diagrammatic cross section through the silo.

Figure 2 is a diagrammatic plan view of the interior of the silo.

Figure 2A is a diagrammatic plan view of the interior of another silo in accordance with the invention.

Figure 2B is a diagrammatic plan view of the interior of yet another silo in accordance with the invention.

Figure 3 is a diagrammatic cross section to an enlarged scale of a solid/rigid base in accordance with the invention.

Figure 4 is a diagrammatic illustration of pneumatic connections to the conveyor unit.

Figure 5 is a diagrammatic cross section of a control valve used in the conveyor apparatus.

Figure 6 is a schematic block diagram of the conveyor apparatus as applied for a plurality of silos.

Figure 7 is a timing diagram relating to the operation of the conveyor apparatus.

Referring to the drawings, Figure 1 shows a silo 1 including a conveyor unit 2 forming part of conveyor apparatus constructed in accordance with the invention. The silo 1 has a flat base 3, resting directly on the ground 4, and provided with the conveyor unit 2.

The exit port of the silo 2 is indicated diagrammatically at 5. Grain stored in the silo 2 is shown as reference 6 and Figure 1-shows the grain after the silo has been partially emptied by a conventional method. The grain 6 remaining in the silo 2 is in a sloping heap at the back of the silo and no longer flows freely towards the exit port 5. The conveyor unit 2 serves to render the grain 6 free-flowing and to convey it to, and out of, the exit port 5.

Figure 2 is a plan view in which the general form of the conveyor unit 2 can be seen. The conveyor unit 2 takes up the whole of the floor area of the silo 1 and projects out through the exit port 5. The conveyor unit 2 comprises a multiplicity of members 7 which are capable of expanding or contracting their crosssection according to the pressure (positive or negative) of air applied to them. The air-actuable members 7 are arc-shaped and arranged side by side, their elongate shape and side by side arrangement being reminiscent of ribs. The arcs run generally parallel to each other. For simplicity of illustration, relatively few air-actuable members 7 have been shown in the silo 1 but in practice a silo 300 cms square might include 75 air-actuable members.

Figure 2A shows an alternative arrangement in which air-actuable members 7' are arranged concen trically about a centrally-placed exit port 5' of a silo with an emptying funnel. It is not essential thatthe members 7' shall defines circles or parts of circles as other concentric arrangements are possible.

Figure 28 shows an alternative arrangement in which straight air-actuable members 7" are arranged generally parallel in a silo of circular section with a side exit port 5". Arcuate air-actuable members could alternatively be employed.

A cross-section through the "ribs" or air-actuable members 7 is shown in Figure 3. A base-plate 8 is provided for the "ribs" or members 7 and channels 9 are provided in the upper surface of the base plate and follow the contours of the arcs seen in Figure 2.

Each channel 9 contains a respective square-section pipe or tube 10 for pressurized air supply and exhaust. The tubes 10 are of any suitable material and each is closed at one end and connected to an air supply manifold (Figure 4) at the other end.

Rigid triangular-section walls 11 following the contours seen in Figure 2 are mounted on the base-plate 8 in sealed relation thereto. Aflexible elastomeric sheet 12, preferably of polyurethane, is mounted over the apices of all the walls 11 and sealingly-connected to the walls by integrallyformed strips 13 adhesively secured to the bars. The normal configuration of the elastomeric sheet 12 is parallel to the base-plate 8 but, as will be explained in more detail later, it can be shifted from that configuration by positive or negative air pressure.

It is apparent from Figure 3 that each adjacent pair of walls 11 sealingly mounted on the base-plate 8 and topped by the sealingly-connected elastomeric sheet 12 defines an air chamber 14. These air chambers 14 are closed off at the ends of the walls 11 by end sealing walls (not shown) but each air chamber 14 communicates with the interior of its associated tube 10 by means of a series of holes 15 in the upper wall of the tube.

If a particular one of the tubes 10 is connected to a supply of air under pressure, the air passes through the holes 15 of that tube and causes the part of the elastomeric sheet 12 forming a wall of the associated air chamber 14to be elastically deformed and bulge outwardly. Conversely, if suction is applied to a particular one of the tubes 10, the associated part of the elastomeric sheet 12 is drawn down into the space between the associated bars.

The multiplicity of members 7 are notionally counted off into threes and connected to air-supply manifolds 20, 21 and 22 as shown in Figure 4. All the first members 7 of the notional threes are connected to the first manifold 20, all the second members 7 are connected to the second manifold 21, and all the third members 7 are connected to the third manifold 22. The commonly connected first members 7 are referenced in the drawings as group I, the commonly-connected second members 7 as group il, and the commonly-connected third members 7 as group Ill.

Each air-supply manifold 20, 21, 22 is connected to a respective control valve, one such valve 30 being shown diagrammatically in Figure 5. The valve 30 is a solenoid operated change-over valve (no attempt has been made to illustrate the solenoid) and comprises a cylinder 31 with inlet ports 32 and 33, and outlet ports 34 and 35 commonly-connected to a conduit 36 leading to the associated manifold 20, 21 or 22. A piston 37 with two annular grooves for air flow is provided in the cylinder 31 to enable either the interconnection of ports 32 and 34 or the interconnection of ports 33 and 35 to be selected according to the state of energisation of the soie- noid. Port 32 is connected to a pressure source and port 33 is connected to an exhaust source.

Figure 6 shows in block schematic form the sources of pressure and exhaust, the control arrangement of the control valves, and the extension of the system to several silos.

A compressor/pump unit 40 is connected to a pressure tank 41 on its high pressure side and connected to an exhaust tank 42 on its low pressure or exhaust side. A vacuum relief valve 43 (to guard against excessive vacuum) is connected to the exhaust side of the compressor/pump unit 40 and a pressure relief valve is connected to an outlet 45 of the pressure tank 41. The outlet 45 serves as the source of pressure for the control valves 30 and the exhaust tank 42 serves as their exhaust source.

The control valves 30 are under the control of an electronic control unit 50 which actuates the solenoids of the control valves in a timed sequence.

Preferably, the electronic control unit 50 is realised in microelectronic form utilising a micoprocessor.

Each silo includes a respective conveyor unit 60 of the type shown in Figures 2 and 3 and a respective ON/OFF valve 61 under the control of the electronic control unit 50 is interposed between the control valves 30 and each conveyor unit. Of course, if there is only a single silo, it can be connected directly to the control valves 30 without the need for any ON/OFF valves.

Figure 7 shows the timing of the switching between pressure and exhaust by the control valves 30 and the expansion and contraction of parts of the elastomeric sheet 12. The groups I, II and Ill control valves are operated in sequence as shown although the pressure/exhaust duty cycle may differ from that shown as may the relative phasing of the three groups, best results in a particular application being ascertainable by experiment. The corresponding expansion and contraction of parts of the elastomer sheet 12 is not, however, representable by precise square waves because of the time needed for air to flow and the fact that the parts of the sheet have to be deformed by the pressure and exhaust. The expansion and contraction of parts of the elastomer sheet 12 is somewhat as represented in the lower part of Figure 7 which gives a rough indication as to what may be expected in practice. An explanation of the conveying action will now be given.

At the pointA marked in Figure 7 the members 7 of group Ill are fully contracted and any grain lying above them will fall by gravity into the pocket so created (see Figure 3). The group lil members 7 then begin to rise and at the point B are in theirflat or undeformed condition. The group Ill members continue to rise and are partly expanded at the point C.

At this instant, the group II members 7 are fully expanded and the group I members fully contracted and as a result the grain raised by the group Ill members tends to be thrown and/or spill off into the pocket created by the group I members. Thus, the grain has moved from the group Ill members 7 to the group I members and these in turn pass it on to the group II members. In this way a conveying action is exerted on the grain.

The above analysis ignores the effects of the weight of the grain at the deepest parts of the heap.

At those parts, the weight of the grain may be sufficient to deform the elastomeric sheet 12 and bicok its expansion. The pressure relief valve 44 ensures that a destructively-high pressure cannot be applied to the fluid-actuable members 7 but it is possible that some "ballooning" could occur if all except the part nearest the manifold were weighed down with grain. To guard against such "ballooning" the holes 15 have different sizes along the length of the tubes 10 with smaller holes near the manifold and larger holes remote from the manifold.

By this means, the flow of fluid to and from the chambers 14 is made more restricted closer to the source of pressure and exhaust to provide some measure of equalisation of the expansion effect.

It is also to be noted that it is of no particular significance if the fluid-actuable members underthe deepest parts of the heap of grain 6 are quite unable to expand owing to the weight of grain above them.

The fluid-actuable members under the shallower parts of the heap will render the grain above them free-running and convey itto the exit port 5 and by this means the heap will be gradually reduced until eventually all the fluid-actuable members will be able to expand.

Supposing that the ribs of fluid-actuable members are numbered off 1,2,3, 1,2,3; 1,2,3 etc ('3' being nearest to the exit port), then the action of the conveyor apparatus may be explained as follows: 1. By inflating all the ribs No. 1 at the same time, any material resting on top will be thrown forward into ribs No. 2.

2. By deflating ribs No. 1 and inflating ribs No. 2, the material (provided that it is suitable for treatment in this way) will be thrown forward into ribs No. 3.

3. By deflating ribs No. 2 and inflating ribs No. 3, the material will be thrown forward into ribs No. 1.

4. By deflating ribs No. 3 and inflating ribs No. 1, the material will be thrown forward into ribs No. 2.

....... and so on.

By this means a kind of "wave" is created which pushes the material along before it. It is not, however, necessary that the material should be a solid material, the invention can also be applied to the conveyance of liquids.

The invention may be used to provide a replace ment for the traditional conveyor belt system and is of particular benefit where a potentially explosive atmosphere exists. The drive drum, idlers, support rollers (all of which need regular service or inspection) and the moving belt (requiring energy to overcome the friction as the belt moves over the rollers and idlers and returns on a sliding bed) of the traditional conveyor belt system can all be avoided by the use of the invention.

Conveyor apparatus according to the invention can be made in a form turning corners without recourse to elaborate mechanical contrivances and can be used to provide easy side ejection of material.

In a silo, conveyor apparatus matching the internal measurements of the silo can be placed in such a way as to push the material or grain towards the discharge point. The necessity for manual intervention is removed and in some cases, at least, the silo may be left sufficiently clean after emptying to avoid the need for manual cleaning. By providing a flat silo floor an increase in storage space is available as no "pits" in the silo base are required.

In the sequence of expansion (or inflation) and contraction (or deflation), the deflation is of particular importance because it has the effect of rendering the material above the fluid-actuable member in question free-running owing to the effect of gravity on the grain left unsupported by the contracted fluid-actuable member.

The dimensions of the fluid-actuable members and the number of pressure/exhaust alternations per minute are chosen with regard to the nature of the material to be transported. The apex to apex distance of the walls 11 may, for example, be 40 millimetres and the number of alternations 35 per minute when transporting grain.

The invention has a wide variety of applications, for example, emptying any kind of grain, or powders such as chalk and cement from silos; conveying easily damaged or dangerous material such as fruit or explosives; material ejection from flat beds; applications in the food industry and engineering; moving fish and ice; conveying pills and tablets in the production of medical products; displacing liquids, for emptying ships, moving oil, moving sea water in tidal beds and salt beds, and moving sewage sludge.

Modifications of the described and illustrated apparatus are, of course, possible.

It is possible to omit the ON/OFF valves 61 and to replace the two-way control valves 30 by a respective set of three-way valves for each silo, the three-way valves providing an OFF position in addition to the two ways of the valves 30. Thus, the conveyor apparatus of a particular silo could be turned off by setting its control valves to the OFF position. Where the silos are widely spaced, it may be desirable to adopt this latter arrangement in order to avoid long lengths of piping between a conveyor unit and its control valves.

It is also possible to replace the two-way control valves 30 by pairs of ON/OFF valves operated in complementary fashion.

For some applications, it may be satisfactory to switch between pressure and a vented condition, or to switch between exhaust and a vented condition rather than between pressure and exhaust.

Instead of operating the air-actuable members in groups of three (1,2,3; 1,2,3... and so on) it is possible to operate them in groups of five (1,2,3,4,5;1,2,3,4,5 and so on).

The tubes 10 do not need to be of square section but may, for example, be round or oblong.

If desired, twice as many integrally-formed strips 13 may be provided so as to secure the elastomeric sheets 12 on both sides of the apex of each wall 11.

Claims (22)

1. Conveyor apparatus using a solid or rigid base with solid or rigid upright walls arranged side by side with suitable spacing between them. Across the tops of these solid or rigid walls is fixed a flexible membrane which flexes positively or negatively in relation to the tops of the walls depending upon the pressure within the air chamber between the upright walls and beneath the flexible membrane. In the negative position the membrane is drawn between the solid or rigid walls causing any material above to fall into the depression and in the positive position the membrane expands from the depression to above the solid or rigid walls causing any material to fall from this new position.

By flexing the membrane from negative to positive positions in a sequential manner and at a suitable cadence a conveying action is achieved.

2. Conveyor apparatus as claimed in claim 1 wherein the solid or rigid walls are arcuate and generally parallel as seen in plan.

3. Conveyor apparatus as claimed in claim 1 wherein the solid or rigid walls are straight and generally parallel as seen in plan.

4. Conveyor apparatus as claimed in claim 1 wherein the solid or rigid walls are arranged concentrically as seen in plan.

5. Conveyor apparatus as claimed in claim 1 wherein the flexible membrane runs from one to another of a pair of solid or rigid walls upstanding from a base member.

6. Conveyor apparatus as claimed in claim 1,5 wherein the flexible membrane is a common sheet of elastomeric material.

6A. Conveyor apparatus as claimed in claims 1-5 wherein the flexible membrane is a composite of sections of a flexible membrane.

7. Conveyor apparatus as claimed in claim 1-5 wherein the flexible membrane is attached by integrally-formed sealing strips.

8. Conveyor apparatus as claimed in any proceding claim, wherein the fluid control means is operative to apply positive and negative pressure alterna timely to the air chambers.

9. Conveyor apparatus as claimed in any preceding claim, wherein the fluid control means includes relief valve means to limited the maximum differential between atmospheric pressure and the pressure applied to the air chambers.

10. Conveyor apparatus as claimed in claim 8 and 9, wherein the relief valve means comprises a positive pressure relief valve and a negative pressure releif valve.

11. Conveyor apparatus substantially as herein described with reference to, and as illustrated by, Figures 3,4,5 and 6 of the accompanying drawings.

12. Conveyor apparatus as claimed in any preceding claim wherein the solid or rigid walls have a triangular section.

13. Conveyor apparatus as claimed in any preceding claim wherein the solid or rigid walls have a circular section.

14. Conveyor apparatus as claimed in any preceding claim wherein the solid or rigid walls have a semi circular section.

15. Conveyor apparatus as claimed in any preceding claim wherein the solid or rigid walls have a square or rectangular section.

16. Conveyor apparatus as claimed in any preceding claim wherein the solid or rigid walls have a styled section, as for example an S.

17. A silo having a floor provided with a deformable surface, a multiplicity of solid/rigid walls with chambers allowing the deforming of a respective part of the floor and fluid control means arranged to control the pressure within the chambers in a sequential manner so that the deformation of the surface provides a conveying action along the top of the deformable surface.

18. A silo as claimed in claim 17 wherein the deformable surface occupies substantially the whole of the corss-sectional area of the silo.

19. A silo as claimed in claim 17 and 18 wherein the floor of the silo is substantially flat.

20. A plurality of silos as claimed in claim 17, 18, 19 wherein a common fluid control means is provided for all the silos and means are provided to select the operation of any particular silo for operation.

21. A silo as claimed in any of the claims 17-29 as a plurality of silos as claimed in claim 27, wherein the fluid actuable means and fluid control means constitute conveyor apparatus as claimed in any claim of 1-16.

22. A silo as claimed in claim 17 or a plurality of silos as claimed in claim 20, substantially as herein described with reference to, and as illustrated by, Figures 1,2,3,4,5 and 6 or by Figures 1, 2A, 3,4,5 and 6 or by Figures 1, 28,3,4,5 and 6 of the accompanying drawings.