GB2307893A

GB2307893A - Bulk Material Loader

Info

Publication number: GB2307893A
Application number: GB9525126A
Authority: GB
Inventors: John Michale Cummings; Geoffrey Ashley Greenwood; Paul Clarke; Patrick Boughey
Original assignee: COCKSEDGE ENG Ltd
Current assignee: COCKSEDGE ENG Ltd
Priority date: 1995-12-08
Filing date: 1995-12-08
Publication date: 1997-06-11
Anticipated expiration: 2015-12-08
Also published as: GB9525126D0; GB2307893B

Abstract

A bulk material loader having a conveyor (2) for projecting into a container (1) into which a bulk granular or pulverulent material is to be loaded, means (3) for loading the material into the rear end of the conveyor so that it will be discharged at its forward end (4) into the container, a bulk material presence sensor, preferably an ultrasonic sensor (8) mounted to sense the rising level of bulk material in the container as it falls, and means (14) for rearwardly retracting the conveyor in response to signals received from the presence sensor Preferably, the conveyor is retracted in steps, either under control of a timer or a travel sensor and the retraction is preferably initiated when the signal reflection time reduces below a pre-set threshold.

Description

Bulk Material Loader This invention relates to a loader for loading bulk granular or pulverulent material into a transport container, sometimes known as a shipping container. A bulk material loader typically comprises a conveyor which projects through an open front end of a container towards a closed hack end thereof, together with means for progressively retracting the conveyor away from the closed back of the container as the container becomes progressively filled with material from the closed back towards the open front.

Retraction of the conveyor may be controlled by manual switching, as by an operator watching the filling of the container. U.K. Patent Specification No. 2 222 397, however, provides for automatic monitoring of the filling process and automatic retraction of the conveyor when necessary by monitoring the energy needed to drive the conveyor, Thus, when the discharge end of the conveyor is discharging into space already filled, more current is needed to power the electric motor driving the conveyor and, when this current rises above a threshold value, a conveyor retraction means is switched on.

The ahove described known method of sensing is not wholly satisfactory however, as the energy required to drive the conveyor can sometimes rise sufficiently to exceed the threshold for extraneous reasons.

According to the invention, there is provided a bulk material loader comprising a conveyor for projecting into a container through an opened front end thereof towards a closed back end thereof, means for feeding bulk material to the conveyor so that in use the material is discharged into the container from the innermost end region of the conveyor, a bulk materials presence sensor carried by the conveyor at or adjacent its innermost end region, means for retraacting the conveyor away from the closed hack end of the conveyor towards its opened front end, and means whereby the retraction means is operated progressively to retract the conveyor as the sensor detects the adjacent presence of hulk material as the container is progressively filled.

The bulk material loader of the invention can be used for loading a container with grain or tea or any of a wide range of granular or particulate materials which can conveniently be transported by container.

The presence sensor may be a proximity sensor of any convenient kind, but in a practical embodiment an ultrasonic sensor is employed. This sensor effectively measures the time taken for an ultrasonic signal to be returned by reflection from the already loaded material. Assuming, as is conventional, that the conveyor is positioned at high level within the container, the signal reflection time reduces as the level of the bulk material rises, and in use the conveyor retraction means is switched on when the signal reflection time reduces below a preselected threshold.

The conveyor is preferably retracted in steps the extent of which is governed either by a travel sensor or more preferably by a timing device. Assuming the conveyor, which preferahly runs continuously, is always retracted at the same speed, the timing device will cause the conveyor to be retracted in substantially equal steps.

Depending on the relative positions of a conveyor discharge opening and the presence sensor, and the setting of the threshold for the signal reflection time, the invention can, if desired, enable retraction of the conveyor so that it always discharges into free space, or at least space where the material is as yet only loosely packed, which reduces risk of clogging of the conveyor at its discharge end.

A preferred retraction means for the conveyor is a carriage on which the conveyor is mounted to prqiect forwardly therefrom, adjacent the roof of the container, through a distance sufficient to reach substantially to the back of the container to he loaded, the carriage heing mounted on rails supported by a platform, which may he a wheeled platform to facilitate its manoeuvrability, as by means of a tractor. The carriage preferably has wheels which run on the rails, including at least one driven wheel powered by a prime mover, preferably an electric motor.

Thus, in use, the presence sensor causes the electric motor to be switched on for a relatively short duration determined by the setting of the timing device, whereby to retract the carriage, and thus the conveyor, through a predetermined distance, each time the sensor is triggered by the adjacent presence of the bulk material as the container is progressively filled from its closed back end towards its open front end.

A preferred conveyor is a twin beam conveyor having screws rotating within tubes which have discharge openings at their forward ends. The tubes also have elongate feed openings rearwards of the discharge end, enabling the hulk material to be input to the conveyor tubes, as from one or more hoppers or other feed means. The feed means is fixed in an overhead position, e.g. on a gantry, and the elongate feed openings travel beneath the feed means as the conveyor is retracted.

The two conveyor beams preferably lie in spaced parallel side-by-side relationship, whereby to achieve loading of the container substantially uniformly across the width of the container.

As the twin beam conveyor is positioned adjacent the roof of the container, the container will fill up to the roof in front of the forward end of the conveyor, with a sloping surface of bulk material extending from the roof downwardly and towards the opened front end of the container. The presence sensor is therefore preferahly mounted, conveniently with means for adjustment along the length of the conveyor, to sense the presence of material beneath the forward end of the conveyor, where the material has the aforesaid sloping surface. Thus, an ultrasonic sensor may emit repetitive signals downwardly, and possibly also partly forwardly, to receive a reflection signal from the sloping surface of bulk material.

If necessary, conventional electronic gating methods may be employed to ensure that the reflected signal is reliably detected, although this may not be necessary as only a relatively slow repetition frequency is required for the emitted ultrasonic signals.

A practical embodiment of bulk material loader in accordance with the invention is diagrammatically illustrated in the accompanying drawings, in which: Figure 1 shows the loader in side elevational view, in cooperation with a container which has already been partly loaded with bulk material; and Figure 2 is a scrap view showing the front end of the conveyor.

Referring to the drawings, a platform 6 having not shown ground wheels carries rails 13 on which a carriage 14 is movahle back and forth under the control of an electric motor 5 operating on a driven wheel 15.

The carriage 14 carries a twin beam conveyor 2, the front end of which, where the bulk material to he loaded is discharged, is shown in Figure 2. The conveyor 2 is a conventional screw-type conveyor driven by an electric motor 7, conveniently common to the two beams. Bulk material is fed in through a slotted feed opening from a loading device 3 fixed in an overhead position, and is conveyed by the rotating screws l6 to the front end 4 of the conveyor, where it is discharged.

As shown, the hulk material, such as grain, is discharged into a transport container 1, which in Figure 1 is shown to have already been partly loaded with the bulk material 17.

As is conventional, the conveyor 2 extends through an opened front end 18 of the container 1 towards a closed back end 19, adjacent the roof of the container. As the container becomes progressively filled, the carriage 14 which carries the conveyor 2 is progressively retracted (to the left as illustrated), as is also conventional practice.

In accordance with the invention, retraction of the conveyor is automatically monitored and controlled.

This is achieved by means of an ultrasonic sensor 8, mounted on an adjustment rail 9 at or adjacent the discharge end of the conveyor 2 (see also Figure 2). The sensor emits ultrasonic signals at a slow repetition rate, directed downwardly to he reflected from the sloping face 20 of the bulk material 17 already loaded into the container 1. As discharge of material progresses, the sloping face 20 displaces towards the opened front of the container, and thereby rises towards the sensor 8.

The time taken for an emitted signal to be returned by reflection to the sensor thus gradually reduces. When this reflection time reduces to a critical threshold, indicated by the sensing distance 12 in Figure l, the sensor triggers operation of the motor 5 which drives the carriage 14. The motor 5 is operated for a predetermined time set by a timer 10, thereby to retract the carriage 14, and thus the conveyor 2, through a predetermined distance. Reference 11 denotes a control box which includes manual stop/start controls for the carriage, used at the beginning and end of loading. These controls are by-passed during automatic loading control.

1t will be appreciated that by adjusting the position of the sensor 8 and/or the sensing distance 12, it is possible to optimise loading conditions, for example having due regard to the nature of the bulk material heing loaded, to minimise risk of clogging of the conveyor 2 at the discharge end 4, while at the same time ensuring that the container 1 is fully loaded up to the roof.

Claims

1. A bulk material loader comprising a conveyor for projecting into a container through an opened front end thereof towards a closed back end thereof, means for feeding bulk material to the conveyor so that in use the material is discharged.into the container from the innermost end region of the conveyor, a bulk materials presence sensor carried by the conveyor at or adjacent its innermost end region, means for retracting the conveyor away from the closed back end of the container towards its opened front end, and means whereby the retraction means is operated progressively to retract the conveyor as the sensor detects the adjacent presence of bulk material as the container is progressively filled.

2. A bulk material loader according to claim 1, wherein the presence sensor is an ultrasonic sensor.

3. A bulk material loader according to claim 2, wherein the sensor effectively measures the time taken for an ultrasonic signal to be returned by reflection from the already loaded material.

4. A bulk material loader according to claim 3, wherein, with the conveyor positioned at high level within the container, the signal reflection time reduces as the level of the bulk material rises, and in use the conveyor retraction means is switched on when the signal reflection time reduces below a preselected threshold.

5. A bulk material loader according to any of claims 1 to 4, wherein the conveyor is retracted in steps the extent of which is governed by a travel sensor.

6. A bulk material loader according to any of claims 1 to 4, wherein the conveyor is retracted in steps the extent of which is governed by a timing device.

7. A bulk material loader according to claim 6, wherein the conveyor runs continuously and is always retracted at the same speed, so that the timing device causes the conveyor to be retracted in substantially equal steps.

8. A bulk material loader according to any of claims 1 to 7, wherein the relative positions of a conveyor discharge opening and the presence sensor, and the setting of the threshold for the signal reflection time, are such as to enable retraction of the conveyor so that it always discharges into free space, or at least space where the material is as yet only loosely packed, which reduces risk of clogging of the conveyor at its discharge end.

9. A bulk material loader according to any of claims 1 to 8, wherein the retraction means for the conveyor is a carriage on which the conveyor is mounted to project forwardly therefrom, adjacent the roof of the container, through a distance sufficient to reach substantially to the back of the container to be loaded, the carriage being mounted on rails supported by a movable platform.

10. A bulk material loader according to claim 9, wherein the carriage has wheels which run on the rails, including at least one driven wheel powered by a prime mover.

11. A bulk material loader according to any of claims 1 to 10, wherein the conveyor is a twin beam conveyor having screws rotating within tubes which have discharge openings at their forward ends.

12. A bulk material loader according to claim 11, wherein the tubes also have elongate feed openings rearwards of the discharge end, enabling the bulk material to be input to the conveyor tubes, as from one or more hoppers or other feed means.

13. A bulk material loader according to claim 12, wherein the feed means is fixed in an overhead position, e.g. on a gantry, and the elongate feed openings travel beneath the feed means as the conveyor is retracted.

14. A bulk material loader according to any of claims 1 1 to 13, wherein the two conveyor beams preferably lie in spaced parallel side-by-side relationship, whereby to achieve loading of the container substantially uniformly across the width of the container.

15. A bulk material loader according to any of claims 1 to 14, wherein the presence sensor is mounted to sense the presence of material beneath the forward end of the conveyor, where the material has a sloping surface.

16. A bulk material loader acording to claim 15, wherein the presence sensor is mounted with means for adjustment along the length of the conveyor.

17. A bulk material loader according to claim 2 or any claim appendant thereto, wberein the ultrasonic sensor emits repetitive signals downwardly, and possibly also partly forwardly, to receive a reflection signal from a sloping surface of bulk material.

18. A bulk material loader according to claim 17, wherein electronic gating methods are employed to ensure that the reflection signal is reliably detected.

19. A bulk material loader substantially as hereinbefore described with reference to the accompanying drawings.