GB2076544A - Measuring System for Spraying Equipment - Google Patents

Abstract

A system for determining the spray density of liquid being distributed by mobile spraying equipment uses a first count 3 of pulses representing the flow of spray medium, from transducer 1, and a second count 4 of pulses representing the distance travelled, from transducer 2. In order to derive the spray density independently of time, a comparator 6 is provided to reset a store 5 when the accumulation of pulses in counter 3 reaches a predetermined count 7. After division 8, the spray density is displayed either directly 12 or as a relative departure from a set value 16. Boom width and other constant factors can be applied to give values such as total volume sprayed 19, total distance 22 and area 24 covered. The distance pulses can also be used with a separate clock 25 to give a speed indication 35. <IMAGE>

Description

SPECIFICATION Improvements Relating to Spraying Equipment This invention relates to spraying equipment, and it is concerned with the determination of the volume of spraying liquid applied per unit area of ground. In this specification the term "liquid" is intended also to embrace very fine powder or particulate material which can be made to flow and spray in the manner of true liquid.

The prime use for such equipment is agricultural, for example spraying fertilizers, herbicides, fungicides and so on, but there are other applications.

Various proposals have been made for determining the volume distributed per unit area, and generally at sommomso so so so someome point there is a division of the flow rate of the spraying liquid by the speed of the carrying vehicle over the ground. Flow rates are obtainable from proprietary meters and speed is usually available from the vehicle instrumentation. Both these parameters involve time, and when the division is made this time factor should cancel out. Nevertheless, it is an unnecessary element to have in the first place, and it could lead to errors if the time basis for the flow and speed meters are not identical. The aim of this invention is to eliminate time altogether when computing volume per unit area.

According to the present invention there is provided a device for determining the volume of spraying liquid which is applied per unit area of ground by spraying equipment, the device comprising means for generating and counting a first series of electrical impulses representing the passage of spray medium through the equipment, means for generating and counting a second series of electrical impulses representing the passage of the equipment over the ground, means responsive to the accumulation of these impulses to divide the first count by the second count and to reset the counting means when the accumulation reaches a given level, and means for displaying the result of that division as an indication of the spray density.

Thus periodically there is an up-dating of the indication of the spray density. The period is not determined by time at all, but only when a counter has registered sufficient impulses. In practice under normal spraying conditions this will be quite frequent enough.

Generally, a flow meter will produce more pulses than a transducer associated with one of the vehicle wheels giving distance pulses. So the preferred arrangement is such that when a sufficient volume of spray medium has passed the first counting means the device is primed for the next division and reset. This is not immediate, since that event should occur simultaneously with the arrival of a distance pulse, so that the division is made by a known definite distance and resetting is carried out at a known starting point.

It is therefore arranged that the division and reset is triggered when the next distance pulse arrives.

Clearly, the more volume pulses that are accumulated before each division, the higher the resolution. However, this need must be tempered by the requirement for regular and frequent updating.

Various factors will be applied to translate the result of the division into a volume per unit area reading, for example spray boom width, and a factor depending on whether the reading is to be imperial or metric.

Since there are distance pulses available and the boom width factor, it is easy to provide for an indication of the total area covered. This will conveniently have a reset facility to be used at the start of spraying operation. Likewise, the total volume can be derived and indicated from the flow pulses.

A very similar arrangement can be used to derive the speed of the vehicle, using the second series of electrical impulses, and having instead of the first series another series of electrical impulses from a timer. Again, these impulses are accumulated and periodically the distance count is divided by the time count.

For a better understanding of the invention, one embodiment will now be described, by way of example, with reference to the accompanying drawing in which the single Figure is a block circuit diagram of a device for determining the volume of spray liquid applied per unit of ground.

The basic information is derived from two transducers 1 and 2, the transducer 1 providing a train of pulses representing the passage of liquid in some part of the spraying equipment on its way to the spray nozzles, and the transducer 2 providing a train of pulses corresponding to the progress of the vehicle carrying the equipment over the ground. The first pulse train is applied to a first resettable counter 3 and the second pulse train to a second resettable counter 4. The contents of both counters are applied to a reset and store circuit 5 which is periodically triggered by a comparator 6 which compares the contents of the first counter with a resolution factor n, set by circuit 7 and which is activated upon the arrival of distance pulses from transducer 2.

In operation, both counters accumulate pulses from their respective transducers and the pulse counts are fed into reset and store circuit 5. The resolution factor n, is the number of volume pulses required before an up-dating of the final display occurs, and it is the reciprocal of the desired fractional resolution. For example, if accuracy within 2% is required, then the resolution factor n, is 50. There can be facility for altering this factor. Thus the comparator 6 can have no output until the contents of the first counter 3 match or exceed the resolution factor n1. When it has attained this state, there is no output until the arrival of the next distance pulse from transducer 2. It then delivers a triggering impulse to the reset and store circuit 5, which thereupon transmits the current counter contents to a divider 8 and resets the counters 3 and 4. The cycle then repeats.

The divider 8 divides the volume count by the distance count, the latter being a whole number and representing a definite known distance by virtue of the resetting at the arrival of a distance pulse. The triggering impulse may not occur at the precise moment of a volume pulse, but the spacing between those pulses is relatively small, and with a high resolution factor any error is negligible.

The divider also performs four further divisions by numbers n2, n3, n4 and n5 entered in register 9.

n2 is the number of pulses per unit volume from transducer 1 n3 is the distance travelled between pulses from transducer 2, n4 is the fraction of spray liquid which generates pulses at transducer 1 (the transducer may not be in a main flow pipe but in a branch to one of the booms, and therefore the other booms must be allowed for in proportion) and n5 is the width of the spray swathe. Generally, the first two factors n2 and n3 will be fixed. However, it is possible that the fraction n4 might be varied according to the number of nozzles or booms in use, for example, and that the spray width factor n6 might change, not only by altering the number of nozzles but possibly by changing the attitude of the booms.

These factors can be adjusted manually or automatically.

The output of the divider 8 is then applied to multiplier 10, the multiplication factor being a number selected from store 11 depending on whether the indication is to be in metric or imperial measurement. The output of the multiplier is now a reading of the volume per unit area, and this can be shown on a digital display 12.

It is not always convenient or easy for the operator to read and follow such a display.

Generally what is required is a simple indication of whether the spray density is too much, too little or correct, and consequently what corrective action, if any, is to be taken. Therefore, there is also provided a register 13 in which is entered the desired spray density, and this together with the current actual density from multiplier 10 is applied to a divider and subtraction circuit 14. The actual reading is divided by the desired reading and unity is subtracted from the result. The output is then applied to a drive circuit 1 5 which governs a centre-zeroing moving needle display 16. A centred needle shows correct operation and a swing to one side or the other shows the departure from the desired density in plus or minus percentage terms.

Further displays can be obtained from this basic circuit. The transducer 1 also feeds its pulses to a third resettable counter 17, and the contents of this are divided in circuit 18 by the number of impulses n2 per unit of volume and The spray liquid fraction n4, both obtainable from register 9. The total volume derived from this division is displayed at 1 9. The reset of counter 17 will generally be manual, and effected at the beginning of a complete spraying operation.

The distance pulses from transducer 2 are applied to a fourth resettable counter 20 and the contents of this are multiplied in circuit 21 by n3, the distance travelled between impulses from transducer 2. The result is shown at 22, this being a display of total distance covered since reset.

This distance can also be applied to a further multiplier 23 which receives as the other factor the spray width n5 from register 9. The associated display 24 shows the total area covered since reset.

Thus far time has had no part to play. However, if there is no separate indication of the forward speed of the vehicle, use can be made of the pulses from transducer 2 in conjunction with timing pulses from a clock 25. The transducer 2 and clock 25 apply their pulses to a circuit 26 which contains resettable counters 27, 28, a comparator 29, a resolution factor store 30 and a reset and store circuit 31 in an arrangement exactly the same as the corresponding components 3, 4, 5, 6 and 7. Detailed description will therefore not be given, but it will be apparent that at the output there will periodically be issued counts of distance and time pulses.A divider 32 divides the distance count by the time count and this is applied to a multiplier 33 which receives two other factors, one being the number n3 (the distance travelled per pulse from transducer 2) and the other from store 34 being the number of timing pulses per unit time. The result of this multiplication is the speed, which is displayed at 35. Again, it is not always convenient to read a digital display of a particular speed; the driver may simply want to know if he is keeping to a desired speed.

Therefore in an arrangement similar to components 13, 14, 15 and 16 the actual speed is applied, in conjunction with a desired speed from store 36, to a divider and subtraction circuit 37 which feeds to a drive circuit 38 and thence to a centre-zeroing moving needle indicator 39 which shows how close in percentage terms the actual speed is to the desired one.

There are also shown in the Figure three switches 40, closed for normal operation, which are opened in common to interrupt the volume pulses from transducer 1, to disconnect the fourth resettable counter 20 from the distance pulses from transducer 2, and to interrupt the signal to the display 16. This is to stop the instrument recording when not actually spraying, for example when turning at the end of a field or journeying to and from the farm.

Claims (14)

Claims

1. A device for determining the spray density of liquid distributed by mobile spraying equipment, the device comprising means for generating and counting a first series of electrical impulses representing the passage of spray medium through the equipment, means for generating and counting a second series of electrical impulses representing the passage of the equipment over the ground, means responsive to the accumulation of these impulses to divide the first count by the second count and to reset the counting means when the accumulation reaches a given level, and means for displaying the result of that division as an indication of the spray density.

2. A device as claimed in Claim 1, wherein for normal spraying the frequency of the first impulses is greater than that of the second impulses, and the division means is arranged to make the division at the instant of one of said second impulses.

3. A device as claimed in Claim 1 or 2, wherein it is the accumulation of the first impulses to a given level which enables the division and reset.

4. A device as claimed in Claim 3, wherein the given level is adjustable.

5. A device as claimed in any preceding claim, wherein the display means indicates actual volume per unit area.

6. A device as claimed in any preceding claim, wherein there are means for setting a desired spray density and means for comparing this set density with the actual density and for indicating the departure of the actual spray density from the set one.

7. A device as claimed in any preceding claim, wherein the first impulses are accumulated and applied to means for indicating the total volume sprayed.

8. A device as claimed in any preceding claim, wherein the second impulses are accumulated and applied to means for indicating the total distance travelled.

9. A device as claimed in Claim 8, wherein a boom width factor is applied to the accumulated second impulses, and the resultant is applied to means for indicating the total area sprayed.

1 0. A device as claimed in any preceding claim, wherein a clock provides impulses, and these are used in conjunction with the second impulses to indicate speed.

11. A device as claimed in Claim 10, wherein actual speed is displayed.

12. A device as claimed in Claim 10 or 11, wherein there are means for setting a desired speed and means for comparing this set speed with the actual speed and for indicating the departure of the actual speed from the set one.

13. A device as claimed in Claim 10, 11 or 12, wherein there is a counter for the clock pulses and a counter for the second impulses, and means responsive to the accumulation of these impulses to divide the second count by the clock count and to re-set the counting means when the accumulation reaches a given level.

14. A device for determining the spray density of liquid distributed by mobile spraying equipment, substantially as hereinbefore described with reference to the accompanying drawing.