GB2105162A - Granules applicator - Google Patents

Abstract

In the applicator, granules being dispensed are continuously weighed by a weighing device (14, 18) providing a signal indicative of the weight being measured at any time, and this signal is used together with a signal from a ground displacement device (19, 19a, 20, 21) indicating the rate of ground displacement, by a control means (22) to control the setting of a metering valve (13) through which the granules are dispensed from a hopper (11). Thus, the rate of application of granules can be matched to the rate of ground displacement of the applicator. <IMAGE>

Description

SPECIFICATION Granules Applicator This invention relates to a granules applicator, that is to say an applicator device intended to be tranversed over the ground and to dispense granules comprising, or including, chemical aids to prepare the ground for receiving seeds or plants or to aid the healthy growth of established plants.

Granules applicators are widely used in both agriculture and horticulture and when a relatively large area of ground isto be treated by the application of granules a plurality of granules applicators are mounted on a vehicle which is desplaced over the ground, conveniently towed or carried by a tractor.

Granules are dispensed by each applicator through an orifice, the cross-sectional area of which can be varied in dependence upon the forward speed of the vehicle, or the granules are metered by a disc, with pockets in its periphery for receiving the granules the rotational speed of which is directly related to the rate of displacement of the vehicle. Thus, conventional granules applicators dispense granules to a volume/displacement ratio.

A serious disadvantage with conventional volume/distance applicators resides in the fact that the volume measuring device must be replaced, or its speed of operation changed, each time the density or distribution rate is changed.

The present invention seeks to provide a granules applicator capable of affording a desired rate of granules application over a very wide range of distribution ratios.

According to the present invention here is provided a granules applicator comprising metering meansfor continuously dispensing granules from a supply of granules, a weighing means downstream of said metering means and arranged to continuously monitor the weight of granules dispensed through said metering means and to transmit a signal indicative of the actual weight of the granules passing therethrough, a ground displacement measuring means arranged to transmit signals indicative of the actual displacement of the applicator overthe ground from a fixed datum, and control means arranged to receive the signals from the weighing means and from the ground displacement measuring means, to compare said signals with a desired rate of application for the granules, and to transmit signals to said metering means to increase, or decrease, the weight of granules passing through said weighing means when the actual weight of granules varies from the desired weight.

Preferably the metering means comprises a variable orifice, conveniently a variable flow passage through a valve, most preferably a motorised valve, that is to say a valve including a motor for displacing the valve closure member to vary the cross-sectional area of the flow path through the valve. With such a motorised valve arrangement the signals from the control means are conveniently arranged to actuate the motorforthe valve as and when a variation in the cross-sectional area of the flow passage through the valve is required.

Preferably the weighing device comprises a weight-senstive plate over which the granules released from the metering means are caused to flow and, in a preferred embodiment, the device comprises a flexible plate with one or more strain gauges attached thereto arranged to sense deflection of the metal strip due to the weight ofgranules passing over the said strip and whereby the signals from the strain gauges are indicative of the weight of granules passing over the plate.

Preferably the ground displacement measuring comprises a land-wheel, that is to say a wheel of known circumference engaged with the ground and adapted to rotate by frictional engagement with the ground as the applicator supporting means is displaced. Conveniently, the ground engaging wheel is linked to a sensor which emits a signal each time the the land-wheel makes a complete revolusion, or part of a revolution, and that signal is transmitted to the control means as indicative of the displacement ofthe granulator.

Preferably the control means comprises a sensing circuit, adapted to receive the weight signals from the weighing means and the displacement signals from the ground engaging means and to transmit a signal indicative of the actual weight of granules dispensed per unit length travelled, a comparison circuit which compares the signals from the relating circuit with a signal indicative of a desired weight per unit length travelled, and a control circuitwhich emits a signal to vary the metering means, to increase or decrease the flow of granules therefrom, when the comparison circuit indicates a difference in the actual rate of granules dispensed to the desired rate.

The invention will be described further by way of example with reference to the accompanying drawings in which: Figure 1 shows, diagrammatically and particularly in cross-section, a granules applicator in accordance with the invention and, Figure2 shows, diagrammatically, a biock diagram ofthe circuit for the applicator illustrated in Figure 1.

In the illustrated example a hopper 11 discharges granules through a conventional on-offvalve 12, the granules passing through valve 12 pass through a metering valve 13, and from valve 13 the granules pass over a plate 14, defining a weighing means, and therefrom down a duct 15 for distribution over the ground G.

The metering valve 13 includes an adjustable closure member 16, the position of which is controlled by a reversible motor 17 whereby, by controlling the motor 17, the location of the closure 16 can be varied to vary the rate ofgranularflowthroughthevalve 13.

The plate 14 is of flexible material, conveniently a metal sheet, intended to deflect in direct relationship to the weight of granules passing thereover, and the plate 14 includes a plurality of strain gauges (not shown) and which, in combination, transmit an output signal via a line 18 indicative of the degree of deflection of plate 14, and thereby the weight of granules passing over plate 14.

The apparatus also includes a land-wheel 19, freely rotatable relative to the frame (not shown) carrying the granules applicator, andthewheel 19 is always in positive engagement with the ground so as to rotate as the applicator is displaced over the ground. The land-wheel 19 includes a number of elements 19a equally spaced circumferentially about the wheel 19 and a sensor 20, adjacentthewheel 19, is arranged to transmit a signal via a line 21 each time an element 19a passes the location of sensor 20.

The signals transmitted on lines 18 and 21 are fed to a control circuit, generally indicated by reference numeral 22, and the control circuit 22 is adapted to transmit signals on a line 23 to the motor 17 to cause said motor 17 to displace the closure member 16 as required in accordance with a pre-determined programme.

As will be seen from Figure 2 the control circuit 22 comprises a sensing circuit in the form of a counter 24 arranged to receive the signals from line 18 and the counter 24 continuously counts the weight of granules passing over the plate 14 from a zero condition and stores the total weight of granules passed over the plate 14. The pulses from the line 21 are also applied to the counter 24 and, upon receipt of each pulse on line 21, the sum total of the weight stored in the counter 24 is transmitted via a line 25 to a comparison circuit 26, and, simultaneously, the counter 24 is returned to its zero condition ready to start a new weight count.

The circuit 26 compares the pulse weight signals from counter 24 with a standard signal from a settable device 27 via a line 28, if the signal on line 25 is equal to the signal on line 28 the output from the comparison circuit 26 on line 23 is zero so that the motor 17 remains de-activated and the flow passage through the valve 13 remains constant and if the signal received by comparison circuit 26 on line 25 is less or more than the signal received on line 28 the output signal from device 26 on line 23 causes motor 17 to operate to displace closure 16 in one direction orthe other to increase, or decrease the flow of granules through the valve 13.

The on-off valve 12 is conveniently linked to the groundwheel 19 so as to displace to an "on" condition only whilst the ground-wheel 19 is rotating, thus to terminate the flow of granules from the hopper 11 when the apparatus is stationary. The on-off valve 12 also conveniently includes a manual actuating means for closing the valve 12 after the apparatus has made a distributing pass over the ground and is being manoeuvred into position to start a new pass.

It will be appreciated that a granules applicator of the type described will have a means atthe lower end of the duct 15 for distributing granules falling down the duct 15 in the direction transverse to the direction of displacement of the applicator apparatus, the transverse width of ground covered by the applicator will be relatively small and to cover an area of ground the apparatus must make a number of passes.

Nevertheless, when the transverse spread of the applicator is known and the peripheral distance around the land-wheel 19 between adjacent elements 1 9a is known the device 27 when set with a predetermined weight per acre, for example fifteen pounds of granules per acre, can readily translate the imput information to the desired weight of the granules to be distributed between the passage of adjacent elements 1 9a passed the device 20 and the signal indicative of that weight of granules is the signal continuously applied to comparison device 26 via the line 28.

Thus, with the device arranged to operate as described above, the counter 24 continuously counts the weight of granules passing over the weighing plate 14, each time an element 1 9a passes the sensor 20 the total weight stored in the counter 24 is transferred to the comparison circuit 26 and the counter 24 is returned to zero to start a new weight count, and the comparison circuit 26 is continuously relating the actual weight of granules dispensed between adjacent elements 19a with the desired weight of granules to be dispensed and, via line 23, is able to continu ously adjust the flow passagethroughthe valve 13to maintain the desired distribution rate.

It will be appreciated that although the system described above is a "batch-weight" system in that the comparison circuit received sum totals of weight per unit length of displacement, the actual length of displacement between adjacenttotal weights submitted to the comparison circuit 26 can be very small and, thereby, a very close control over the weight distribution of granules can be obtained, even when the rate of distribution of granules per unit area is to be small, that is to say is to be less than ten pounds per acre and, in many cases, less than five pounds per acre.

a Whilst the present invention has been described by way of example with reference to a specific embodiment many modifications and variations will be apparent to persons skilled in the art and all such modifications and variations which relate to a granules applicator which dispenses granules by a weight to displacement ratio, ratherthan the conventional volume to displacement ratio, must be within the scope of this invention.

CLAIMS (Filed 22 July 82) 1. A granules applicator comprising metering means for continuously dispensing granules from a supply of granules, a weighing means downstream of said metering means and arranged to continuously monitor the weight of granules dispensed through said metering means and to transmit a signal indicative of the actual weight of the granules passing therethrough, a ground displacement measuring means arranged to transmit signals indicative of the actual displacementoftheapplicatorovertheground from a fixed datum, and control means arranged to receive the signals from the weighing means and from the ground displacement measuring means, to compare said signals with a desired rate of application for the granules, and to transmit signals to said metering means to increase, or decrease, the weight of granules passing through said weighing means when the actual weight of granules varies from the desired weight.

2. An applicator according to claim 1, wherein the metering means comprises a variable orifice.

3. An applicator according to claim 2, wherein said variable orifice is a variable flow passage through a valve.

4. An applicator according to claim 3, wherein

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

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. positive engagement with the ground so as to rotate as the applicator is displaced over the ground. The land-wheel 19 includes a number of elements 19a equally spaced circumferentially about the wheel 19 and a sensor 20, adjacentthewheel 19, is arranged to transmit a signal via a line 21 each time an element 19a passes the location of sensor 20. The signals transmitted on lines 18 and 21 are fed to a control circuit, generally indicated by reference numeral 22, and the control circuit 22 is adapted to transmit signals on a line 23 to the motor 17 to cause said motor 17 to displace the closure member 16 as required in accordance with a pre-determined programme. As will be seen from Figure 2 the control circuit 22 comprises a sensing circuit in the form of a counter 24 arranged to receive the signals from line 18 and the counter 24 continuously counts the weight of granules passing over the plate 14 from a zero condition and stores the total weight of granules passed over the plate 14. The pulses from the line 21 are also applied to the counter 24 and, upon receipt of each pulse on line 21, the sum total of the weight stored in the counter 24 is transmitted via a line 25 to a comparison circuit 26, and, simultaneously, the counter 24 is returned to its zero condition ready to start a new weight count. The circuit 26 compares the pulse weight signals from counter 24 with a standard signal from a settable device 27 via a line 28, if the signal on line 25 is equal to the signal on line 28 the output from the comparison circuit 26 on line 23 is zero so that the motor 17 remains de-activated and the flow passage through the valve 13 remains constant and if the signal received by comparison circuit 26 on line 25 is less or more than the signal received on line 28 the output signal from device 26 on line 23 causes motor 17 to operate to displace closure 16 in one direction orthe other to increase, or decrease the flow of granules through the valve 13. The on-off valve 12 is conveniently linked to the groundwheel 19 so as to displace to an "on" condition only whilst the ground-wheel 19 is rotating, thus to terminate the flow of granules from the hopper 11 when the apparatus is stationary. The on-off valve 12 also conveniently includes a manual actuating means for closing the valve 12 after the apparatus has made a distributing pass over the ground and is being manoeuvred into position to start a new pass. It will be appreciated that a granules applicator of the type described will have a means atthe lower end of the duct 15 for distributing granules falling down the duct 15 in the direction transverse to the direction of displacement of the applicator apparatus, the transverse width of ground covered by the applicator will be relatively small and to cover an area of ground the apparatus must make a number of passes. Nevertheless, when the transverse spread of the applicator is known and the peripheral distance around the land-wheel 19 between adjacent elements 1 9a is known the device 27 when set with a predetermined weight per acre, for example fifteen pounds of granules per acre, can readily translate the imput information to the desired weight of the granules to be distributed between the passage of adjacent elements 1 9a passed the device 20 and the signal indicative of that weight of granules is the signal continuously applied to comparison device 26 via the line 28. Thus, with the device arranged to operate as described above, the counter 24 continuously counts the weight of granules passing over the weighing plate 14, each time an element 1 9a passes the sensor 20 the total weight stored in the counter 24 is transferred to the comparison circuit 26 and the counter 24 is returned to zero to start a new weight count, and the comparison circuit 26 is continuously relating the actual weight of granules dispensed between adjacent elements 19a with the desired weight of granules to be dispensed and, via line 23, is able to continu ously adjust the flow passagethroughthe valve 13to maintain the desired distribution rate. It will be appreciated that although the system described above is a "batch-weight" system in that the comparison circuit received sum totals of weight per unit length of displacement, the actual length of displacement between adjacenttotal weights submitted to the comparison circuit 26 can be very small and, thereby, a very close control over the weight distribution of granules can be obtained, even when the rate of distribution of granules per unit area is to be small, that is to say is to be less than ten pounds per acre and, in many cases, less than five pounds per acre. a Whilst the present invention has been described by way of example with reference to a specific embodiment many modifications and variations will be apparent to persons skilled in the art and all such modifications and variations which relate to a granules applicator which dispenses granules by a weight to displacement ratio, ratherthan the conventional volume to displacement ratio, must be within the scope of this invention. CLAIMS (Filed 22 July 82)

1. A granules applicator comprising metering means for continuously dispensing granules from a supply of granules, a weighing means downstream of said metering means and arranged to continuously monitor the weight of granules dispensed through said metering means and to transmit a signal indicative of the actual weight of the granules passing therethrough, a ground displacement measuring means arranged to transmit signals indicative of the actual displacementoftheapplicatorovertheground from a fixed datum, and control means arranged to receive the signals from the weighing means and from the ground displacement measuring means, to compare said signals with a desired rate of application for the granules, and to transmit signals to said metering means to increase, or decrease, the weight of granules passing through said weighing means when the actual weight of granules varies from the desired weight.

2. An applicator according to claim 1, wherein the metering means comprises a variable orifice.

3. An applicator according to claim 2, wherein said variable orifice is a variable flow passage through a valve.

4. An applicator according to claim 3, wherein

said valve is a motorised valve,that is, a valve including a motor for displacing the valve closure member to vary the cross-sectional area of the flow path through the valve.

5. An applicator according to claim 4, wherein the motor of the valve is arranged to be actuated by the signals from the control means as and when a variation in the cross-sectional area of the flow passage through the valve is required.

6. An applicator according to a ny of the preceding claims, wherein the weighing device comprises a weight-sensitive plate over which the granules released from the metering means are caused to flow.

7. An applicator according to claim 6, wherein the weighing device comprises a flexible plate with one or more strain gauges attached thereto and arranged to sense deflection of the plate due to the weight of granules passing over the plate and whereby the signals from the strain gauges are indicative of the weight of granules passing over the plate.

8. An applicator according to any ofthe preceding claims, wherein the ground displacement measuring means comprises a land-wheel, that is, a wheel of known circumference engaged with the ground and adapted to rotate by frictional engagement with the ground as the applicator supporting means is displaced.

9. An applicator according to claim 8, wherein the ground engaging wheel is linked to a sensor which emits a signal each time the land-wheel makes a complete revolution, or part of a revolution, and the control means is arranged to receive that signal to indicate the displacement of the applicator.

10. An applicator according to any of the preceding claims, wherein the control means comprises a sensing circuit, adapted to receive the weight signals from the weighing means and the displacement signals from the ground engaging means and to transmit a signal indicative of the actual weight of granules dispensed per unit length travelled, a comparsion circuit which compares the signals from the sensing circuit with a signal indicative of a desired weight per unit length travelled, and a control circuit which emits a signal to vary the metering means, to increase or decrease the flow of granules therefrom, when the comparison circuit indicates a difference in the actual rate of granules dispensed from the desired rate.

11. A granules applicator substantiall as herein before described with reference to the accompanying drawings.