GB2046200A - Feed device for a chain and bucket elevator - Google Patents

Abstract

A device controlling the flow of products into buckets of a bucket elevator comprises a feed conveyor the speed of which is made to vary so that the conveyor is moving at its maximum speed when a bucket is situated below the discharge end of the conveyor. The bucket elevator 1 includes a drive chain 3, running on sprockets 7 and 9, on which a plurality of buckets 5 are pivotally supported. To sprocket 7 is connected a drive sprocket 23 which, via chain 25, drives a sprocket 27 mounted on an elliptical driven gear 31. Gear 31 is in contact with a smaller round gear 35 which, via chain 39, sprocket 41, chain 45 and sprocket 17, drives a feeder conveyor 11. Gear 35 is mounted on a swinging arm 37 and biassed into contact with gear 31 at all times. The arrangement of gears is such that the speed of conveyor 13 reaches a maximum each time a bucket 5 is immediately below the discharge end of the conveyor. <IMAGE>

Description

SPECIFICATION Feed device for a chain and bucket elevator This invention relates to a feed device for a chain and bucket elevator.

Traditionally, chain and bucket elevators incorporate a plurality of spaced buckets supported on a chain entrained in a closed loop around a plurality of sprocket wheels. When the buckets are to be loaded, there is always the problem of spillage occurring; one way of minimising spillage is to keep the buckets close together on the chain and load the buckets as they pass around a sprocket wheel so that several buckets are located one above another. This presents unloading problems. Alternatively, the buckets can be brought together so that the trailing end of one bucket touches the leading end of another bucket during the loading operation.

While this latter system works fairly satisfactorily, there are problems in bringing the buckets together when the elevator is working in a dusty atmosphere since the dust tends to cause malfunction of the mechanism bringing the buckets together. Also, the chain must travel slowly if the buckets are to be brought together for loading. As a further alternative, the speed ofthe chain can be slowed down just for filling, but this puts a tremendous strain on the drive mechanism and it is preferred to drive the chain at a uniform speed.

The present invention seeks to provide a feed device for controlling the flow of products into the buckets, which overcomes the above problems, allows the buckets to be well spaced on the chain, thus permitting 3600 tipping, and means that the chain can move at a constant high speed.

According to the broadest aspect of the present invention, we provide a feed device for feeding product into the buckets of a bucket elevator and comprising conveyor means for which the product is discharged into the buckets and drive means adapted to be driven from a drive sprocket rotatable with a chain sprocket for the chain of the bucket elevator, the drive means being such that the conveyor means is driven at high speed when the centre of 9 bucket is located below its discharge end and at a slower speed at other times.

Preferably, the drive means includes an endless entrainment means adapted to be entrained around the drive sprocket rotating with the chain sprocket and an input sprocket, the ratio between drive and input sprocket diameters corresponding to the number of buckets which will pass beneath said discharge end for one revolution of the chain sprocket with which the drive sprocket rotates. It will of course be appreciated that the drive sprocket can be associated with any chain sprocket for the elevator.

Preferably, the input sprocket rotates with an elliptical drive member such as a gear wheel, the axis of rotation of the input sprocket and elliptical drive member being located on the major axis of the elliptical drive member, there being a floating drive member engaging with the periphery of the elliptical drive member and a further drive arrangement between the floating drive member and a drive sprocket for the conveyor means to rotate the drive sprocket at a speed proportional to the speed of rotation of the floating drive member.

In a particular arrangement, the floating drive member is supported on the free end of a swinging arm. The floating drive member may comprise a sprocket engageable with the elliptical gear and the further drive arrangement may comprise a chain drive from the floating drive sprocket to a transfer sprocket and a further chain drive from a secondary transfer sprocket rotatable with the transfer sprocket to the drive sprocket for the conveyor means.

Preferably, the discharge end of the conveyor means is located so that it can load buckets either just before or just after they pass around a sprocket wheel and are moving along an inclined path, or as they pass around the sprocket wheel, and several are arranged one above the other, thereby minimising spillage. However, the invention is applicable to filling buckets at any location along the chain.

The invention also extends to a bucket elevator mechanism having a feed device as described above.

A bucket elevator incorporating a feed device in accordance with the present invention is now described by way of example with reference to the accompanying drawing, which is a partly schematic side elevational view.

Referring to the drawing, a small portion of a bucket elevator indicated generality at 1 is shown, the bucket elevator incorporating a drive chain 3 on which a plurality of buckets 5 are pivotally supported in known manner. The chain is entrained around vertically and horizontally spaced chain sprockets 7 and 9. The buckets 5 are.

suitably spaced along the chain 3 to enable them to be tipped through 3600 for discharging their contents and it is preferred that the sprockets 7 and 9 are so arranged that when the buckets pass along the inclined run between the two sprockets, the trailing edge of one bucket will substantially overlap in a horizontal direction the leading edge of another bucket or, alternatively, if there is any horizontal gap between said trailing and leading edges, there will be a further bucket beneath the sprocket 7 located beneath the gap to catch any product being fed to it from a feed device 10, and passing through the gap as a result of spillage from one or other of the buckets or as a result of product being fed to the buckets too quickly.

The feed device 10 according to the present invention includes a conveyor belt 11 having a horizontal upper run 13, the downstream end of which terminates in a pulley 1 5 around which the belt is entrained, the arrangement being such that the discharge end of the horizontal run 13 is located substantially mid-way above the inclined run of the chain 3 between the sprockets 7 and 9.

At the upstream end of the horizontal conveyor run 1.3, the conveyor belt 11 passes around a pulley 1 7 mounted on an input shaft driven by a drive sprocket 1 9.

The chain sprocket 7 is fixed to a shaft 21 which has a drive sprocket 23 for the conveyor means 11 fast thereon. A drive chain 25 is entrained around the sprocket 23 and around the input sprocket 27 rotatable about an axis 29. The ratio of the diameter of the sprocket 23 to that of the sprocket 27 corresponds to the number of buckets 5 which will pass beneath the discharge end of the conveyor belt 1 3 for one complete revolution of the chain sprocket 7.

Rotatable with the input sprocket 27 about the axis 29 is an elliptical drive member 31, preferably a gear, on the major axis 33 of which the rotational axis 29 is located. A floating drive member, e.g. a gear wheel 35, rotatably supported on a support arm 37 is in meshing engagement with the elliptical drive gear 31. Rotatable with the gear wheel 35 about the same axis is a pulley or gearwheel around which is entrained an endless drive member, e.g. a chain 39. The chain 39 is also entrained around a transfer sprocket 31 rotatable about an axis 43 about which the arm 37 also swings. A further endless drive member such as a chain 45 is entrained around a secondary transfer sprocket rotatable with the sprocket 41 about the axis 43 and about the conveyor drive sprocket 19.

It will thus be appreciated that as the bucket elevator advances the buckets 5 past the discharge end of the conveyor belt 13 so the buckets will be filled in a controlled manner. The elliptical gear 31 will rotate about the axis 29 at a uniform speed but because the gear is elliptical, the gear wheel 35 meshing with it will rotate at a different angular velocity. In the position shown, the angular velocity of the gear wheel 35 is at a minimum, thus ensuring that the conveyor belt 1 3 advances at slow speed so as only to feed a small quantity of product into the bucket 5.This is desirable because an edge region only of the bucket is located beneath the discharge end of the belt 1 3. However, as the elliptical gear is rotated, the angular velocity of the gear wheel 35 will increase to a maximum at the point at which the elliptical gear wheel 31 has rotated through 1 800 from the position shown in the drawing. At this time, the centre of the bucket 5 will be located beneath the discharge end of the conveyor belt 1 3. Obviously, because the gear wheel 35 has it maximum angular velocity at this time, the feed rate of product from the belt 1 3 will be at a maximum which is exactly what is desired. Further rotation of the drive sprocket 23 will cause the gear wheel 35 to slow down, thus slowing down the rate of feed from the belt 13 to a minimum as the trailing edge of one bucket 5 moves beneath the discharge end of the belt 13 and the leading edge of the next bucket moves into position.

The cycle will then be repeated indefinitely as each bucket moves beneath the discharge end of the conveyor belt.

The rate of change of speed of the gear wheel 35 can be altered by changing the shape of the elliptical gear wheel 31 and/or by changing the location of the axis 25 on the major axis of the elliptical gear wheel 31.

Claims (11)

1. A device for feeding material into the buckets of a bucket elevator, the buckets being supported on one or more chains or ropes, the device comprising conveyor means by which the product is discharged into the buckets and means for driving said conveyor means, said driving means in turn being driven by bucket elevator drive means through gearing so arranged that the speed of the conveyor means is at a maximum when a bucket is located below the discharge end of the conveyor means.

2. A device according to claim 1 and in which the bucket elevator is driven at constant speed.

3. A device according to claim 1 or claim 2 and in which the gearing comprises an elliptical drive member in contact with a round driven member, contact being maintained by mounting one of the members on a swinging arm and biassing the members towards each other.

4. A feed device for feeding product into the buckets of a chain and bucket elevator and comprising conveyor means from which the product is discharged into the buckets and drive means adapted to be driven from a drive sprocket rotatable with a chain sprocket for the chain of the bucket elevator, the drive means being such that the conveyor means is driven at high speed when the centre of a bucket is located below its discharge end and at a slower speed at other times.

5. A feed device according to claim 4 in which the drive means includes an endless entrainment means adapted to be entrained around the drive sprocket rotating with the chain sprocket and an input sprocket, the ratio between drive and input sprocket diameters corresponding to the number of buckets which will pass beneath said discharge end for one revolution of the chain sprocket with which the drive sprocket rotates.

6. A feed device according to claim 4 or claim 5 and in which the input sprocket rotates with an elliptical drive member, the axis of rotation of the input sprocket and elliptical drive member being located on the major axis of the elliptical drive member, there being a floating drive member engaging with the periphery of the eliiptical drive member and a further drive arrangement between the floating drive member and a drive sprocket for the conveyor means to rotate the drive sprocket at a speed proportional to the speed of rotation of the floating drive member.

7. A feed device according to claim 6 and in which the floating drive member is supported on the free end of a swinging arm.

8. A feed device according to claim 6 or claim 7 and in which the floating drive member comprises a sprocket engageable with the elliptical drive member and said further drive arrangement comprises a chain drive from the floating drive sprocket to a transfer sprocket and a further chain drive from a secondary transfer sprocket rotatable with the transfer sprocket to the drive sprocket for the conveyor means,

9. A device according to any of claims 4-8 and in which the discharge end of the conveyor means is located so that it can load buckets either just before or just after they pass around a sprocket wheel and are moving along an inclined path, or as they pass around the sprocket wheel, and several are arranged one above the other, thereby minimising spillage.

10. A bucket elevator mechanism having a feed device as claimed in any preceding claim:

11. A device for feeding material into the buckets of a bucket elevator substantially as hereinbefore particularly described and as illustrated in the accompanying drawings.