WO2002034033A1

WO2002034033A1 - An agrochemical application system for irrigation equipment

Info

Publication number: WO2002034033A1
Application number: PCT/US2000/041503
Authority: WO
Inventors: Santiago Miguel Prandi
Original assignee: Valmont Industries, Inc.
Priority date: 2000-10-24
Filing date: 2000-10-24
Publication date: 2002-05-02
Also published as: AU2001224692A1

Abstract

An agrochemical applicator for mechanized irrigation systems which applies agrochemicals to crops within the coverage area of the irrigation systems. The applicator of this invention applies the agrochemicals in a manner in which the application is carried out by means of short-duration pulses of the liquid solution onto the surface of the crops. A control link is provided for controlling the time of the pulses from the spray nozzles which are mounted on secondary chemical lines (23) positioned beneath the main water line (22) of the irrigation system. The secondary chemical lines (23) are divided into sections which are fluidly connected to a main chemical distribution line which extends the length of the irrigation system. A micro-controller is mounted on each of the drive towers of the system and senses the activation of the drive tower motor on which the micro-controller is mounted and senses the activation of the drive motor on the drive tower adjacent thereto. The micro-controller calculates the speed of each section of the associated drive tower and is electrically connected to a quick-switching electrically-operated valve which is imposed between the main chemical distribution line and each of the associated sections of the secondary chemical line (3).

Description

AN AGROCHEMICAL APPLICATION SYSTEM FOR IRRIGATION EQUIPMENT

BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION

This invention relates to an agrochemical application system for irrigation equipment and more particularly to an agrochemical application system which is mounted on the irrigation equipment structure so that it is parallel to the plane of the soil which is achieved by suspending spray nozzles thereof in an appropriate manner. 2. DESCRIPTION OF THE RELATED ART

Currently in the field of agriculture, agrochemicals are generally applied in three ways. The first is through aerial applications, which suffer from low efficiency when accuracy is required, in addition to the inability to provide adequate environmental protection due to the factors influencing the application, such as wind, the speed of the plane, spraying altitude, etc. The second is through self-propelled or towed ground sprayers, which are the ones most often used in the world due to their low purchase and maintenance costs. These sprayers have the defect of requiring one or more persons to be constantly exposed to the toxic products used on a daily basis. Unfortunately, all agrochemicals are toxic by nature, some more than others, but none without risk to humans. Furthermore, in order to be used, ground sprayers must travel over the land, which results in the compacting of the soil, which is one of the primary enemies of direct planting. The aforementioned ground sprayers cannot be used at all stages of the crop's growth since as the crops grow taller, the movement of the devices is limited, in which case the only existing means of application are by plane or the use of irrigation equipment. Imgation equipment may be used because it allows agrochemicals to be injected into the water flow used for irrigation although it is the most inaccurate method and the one most damaging to the environment. This is due to the fact that the agrochemical is injected into the water flow by means of various existing systems and methods, and this water flow is then distributed onto the soil through the irrigation sprinkler heads which were designed for imgation rather than for the effective distribution of agrochemicals. In the case of fertilizers, application by this method presents no major problems, since its distribution in the soil, although not precise, is considered acceptable, but in the case of all other agrochemicals such as herbicides, insecticides, fungicides, etc., it is unacceptable from any point of view.

SUMMARY OF THE INVENTION An agrochemical application system for conventional center pivot or linear move irrigation equipment for applying agrochemicals to crops within the coverage area of irrigation equipment, whether central pivot or forward advancing equipment, regardless of its manufacturing origin, in a precise and efficient manner in which the application is carried out by means of short-duration pulses of the liquid solution onto the surface of the crops, said crops being in any stage of growth. The system may vary its operating height up to the maximum clearance existing between the plane of application and the irrigation equipment structure. The innovative part of the invention being the control link which controls the time the pulses are emitted, handled by a micro-controller, which makes decisions by sensing, through the status of the contactors on the motors of the towers which drive the irrigation equipment structure. The type of movement of the section between the tower bearing the micro-controller and the preceding tower, said section being divided in turn into other sections of shorter length which hold the nozzles that perform the spraying, the duration of the liquid solution pulses being part of the innovative aspect of this invention, since it may vary as a function of the dosage required by the type of agrochemical, which shall be selected by the user and stored in the micro-controller, with higher dosages requiring longer pulses.

It is therefore a principal object of the invention to provide an improved agrochemical application system for irrigation equipment.

It is a further object of the invention to provide a system of the type described which does not require any human contact with the agrochemicals.

A further object of the invention is to provide for more accurate applications, thus protecting the environment due to the uniformity of the application and the low drift, thereby reducing impact outside the crop area wherein the agrochemicals would end up evaporating into the air or remain in the soil as residue. It is a further object of the invention to provide a system of the type described which is not subject to incorrect evaluations by the personnel performing the application, since the application is automated. Yet another object of the invention is to provide a system of the type described wherein energy consumption is notably less, since a self-propelled tractor or sprayer operates within an engine of at least 50 hp, while a center pivot or forward-advancing drive system only uses the electric motors on the towers in movement at any given time. Still another object of the invention is to provide a system wherein the applications may be completed in a shorter time, since they are limited only by the minimum rotation time of the center pivot or the maximum speed of a forward-advancing system.

Still another object of the invention is to provide a system which may vary in application height from 75 cm to 2.9 m on a standard irrigation system, with an easy, quick adjustment which allows pest control at any stage of crop growth, which was previously impossible to accurately achieve, since only aerial spraying could be used.

Still another object of the invention is to provide a system including equipment which allows for programmed applications which consider environmental conditions and which are performed under optimum conditions which allows the user to disregard wind and other factors detrimental to the application, since if the programmed thresholds are exceeded, the spraying will stop until they return to acceptable levels.

Yet another object of the invention is to provide a system whereby the irrigation equipment is used as the means of transport, the system allows the grower to perform spraying immediately after a rainfall, which could not be done by any other means without waiting for the ground to dry.

Yet another object of the invention is to provide a system which reduces soil compaction.

Yet another object of the invention is to provide a system which allows fertilizers to be efficiently applied and the entire surface area beneath the irrigation equipment at any stage of crop growth.

Yet another object of the invention is to provide a system which results in fuel savings, labor savings, lower crop loss due to timely applications, and savings in agrochemical quantities due to the application.

These and other objects will be apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic of the invention; and

Figure 2 is a schematic of the circuitry of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In order to implement the invention, a study was conducted on the types of movement used in various types of irrigation equipment. A model of these systems was used and the conclusion was reached that it was feasible to create an independent system for accurate agrochemical applications. Technically, in order to apply agrochemicals, it is necessary to pump the liquid solution of the various products to the nozzles comprising the invention, so a pump station was designed which is able to perform this function on a continuous basis and in turn agitate the agrochemical in solution in the tank to maintain a uniform concentration.

To carry the agrochemical the complete length of the irrigation equipment, it was necessary to determine the piping needed to transport it considering environmental conditions (ultraviolet and infrared light, possibility of frost, etc.) and the hydraulic requirements (diameters necessary to decrease loss of line pressure, pipe wall thickness required to withstand operating pressure, etc.). Once the problem of supplying the agrochemical to the nozzles was resolved, the primary concern of how to control the distribution remained. To do this, applicant made use of electronic technology, employing micro-controllers, which receive data from the transducers that sense the movement of the towers, then process the data and finally, make decisions. These decisions produce effects on electromechanical devices, allowing interaction between the electrical and hydraulic devices. Essentially, in order to handle the dosages required by the user, the Agrochemical

Application System for Irrigation Equipment of this invention uses a control link which determines the times when the pulses of the solution are to be applied on the various surfaces into which the main area is divided. These pulses may vary in duration based on the dosage required for the type of application, environmental conditions (wind, ambient temperature, relative humidity, etc.), the type of nozzle used and the equipment on which it is mounted. In order to describe the Agrochemical Application System for Irrigation Equipment of this invention, it is necessary to define the irrigation systems on which it may be mounted. A central pivot irrigation system operates as a radius vector which rotates around a given point as follows: the system is divided into articulated sections by towers with motorized wheels which make successive movements. These movements are controlled by the last tower, which regulates their speed according to programmed commands. This means that the user controls the system rotation time by determining the activation time of the last tower. This tower will transmit this data to the preceding towers through an electromechanical system placed on the remaining towers for this purpose, which will activate when the tower that initiated the movement has swept across a determined angle.

To summarize, the movement takes place by means of a combination of movements inside the equipment, which must be coordinated to maintain the system's linearity. In the case of a forward advancing system, movements of the sections occur with characteristics similar to those of the central pivot system, except that the equipment's movements are linear over the surface of the irrigated land.

In structural terms, the irrigation equipment is composed of a galvanized steel water line, whose diameter is a function of the flow rate of the water to be transported and the pressure requirements of the sprinklers mounted thereupon. These diameters usually range between 6" and 8". The total length of the equipment is determined by the surface to be irrigated; for example, in the case of a central pivot system which irrigates 100 ha, the equipment is 574 m long.

This piping is divided into variable-length sections (typically 54.4 m) on the end of which is a tower with two motorized wheels driven by an electric motor through a shaft drive. The whole structure is joined using angles, struts, steel cables, etc.

Operating Principle of the Invention

In the case of a central pivot system, the irrigation equipment can be considered a radius vector sweeping across the surface area enclosed within a specific circumference. Given the specificity of this movement, the areas swept by each pivot section are not the same. In turn, the motors and their corresponding reducers operate at a minimal speed, on the order of 3 m/min. For this reason, no system can be used to perform a reduced, efficient pluviometry on the entire area beneath the pivot. In the case of the forward advancing system, the composition of movements is simpler, since it involves a linear movement of the equipment. For this reason the Agrochemical Application System for Irrigation Equipment of this invention bases its control logic on the low-speed movement of each section of the pivot or forward advancing equipment, and on a pluviometry system controlled by short- duration pulses. This means that it will only spray when the section in question has moved a programmed distance based on its relative location within the system, environmental conditions, the crop type and the nozzle used.

This can be explained as follows: given a constant speed of each tower, three possible types of movement will be possible in each of the sections between two towers:

1. Circular movement between the activated tower and the preceding stopped tower; this will be called positive movement (+). 2. Linear movement of the entire section when both towers are activated, called linear movement.

3. Circular movement between the preceding tower which is now activated and the stopped subsequent tower, called negative movement (-).

These three types of movement share a common known speed. For this reason, if this movement can be processed, the times at which the corresponding spraying is to be performed by the nozzles located on the given section can be determined.

By analyzing the movements, which are identical for all the towers except the first tower, which only has the first type of movement, and by using a micro-controller, which with proper programming can process the data and manage the system, this goal can be achieved.

Control Logic of the Agrochemical Application System for Irrigation Equipment

In order to create the system, a micro-controller must be mounted on each of the irrigation system's towers, which will control the section between that tower and the preceding tower. This section will be divided into subsections, as required by the application and the existing crop. Each subsection has a quick-switching electrically- operated valve which connects it to the main line, allowing it to perform the programmed pulses. The micro-controller determines the activation of the electrically-operated valves, which respond quickly in order to allow for short pulse times and safe operation, preventing unwanted spraying. The pressure regulator connected in series with the electrically-operated valve allows the pressure range on the nozzle used to be controlled, thus varying the different drop sizes required by the application.

The dosage per hectare is determined by the duration of the spray pulse, which will depend on the capacity of the nozzle as programmed in the micro-controller. Longer pulse times will allow for higher pluviometries, as required.

Within the section, in the case of a central pivot system, as one moves away from the center, the more distant subsections will spray a greater number of times than the closer ones, as will occur with each section of the pivot system. In a forward advancing system, all subsections will have to spray the same number of times, since the surface area covered by each subsection is identical to the others. On the other hand, in the central pivot system, since it has a circular movement, the areas sprayed by each subsection will increase as the radial distance to the center of the equipment increases.

The selection and placement of the nozzles depends on the type and requirements of each crop to be sprayed, the surrounding environmental conditions, the features and type of irrigation equipment (speed, height, assembly, etc.).

Parts Comprising the Invention

Pump Station

The pump station is comprised of a centrifugal pump, whose capacity will vary for each particular type of equipment, and extracts the solution from a tank containing the agrochemical to be applied. The pump and the tank are connected by means of a pipe which includes a spherical valve to cut off the supply if necessary, and a mesh filter to prevent the passage of sediments into the blades of the impulse turbine. At the pump outlet is another mesh filter which has the function of preventing any foreign matter not trapped by the first filter from passing into the main line. The tank is agitated by the same pump using a jet agitator connected to the network through a pressure-sustaining valve mounted in parallel with the main line, which shunts the unused fluid and allows a constant given pressure to be maintained. The main line which carries the solution to the spray nozzles has a serially connected pressure -regulating valve which allows a constant pressure to be maintained in the event of flow rate fluctuations produced by the opening of the various spray bars placed on the sections of the irrigation equipment. In turn, the system has two pressure sensors, one before the pressure-sustaining valve which verifies the status of the pump and triggers a high pressure alaπn signal; and the other after the pressure-regulating valve which evaluates the correct operation of the pump station. A pressure gauge is included to view the pressure, which is mounted on a three-way selector to inspect different selected points. The electrical energy which drives the pump is taken from the irrigation equipment, and the pump station is activated through the irrigation equipment's control panel, which includes the controls necessary to control the Agrochemical Application System for Irrigation Equipment. These controls include a micro-controller to control the proper operation of the system and the imgation equipment. This is done by sensing the different variables which may affect the normal operation of the equipment. These variables are: 1. That the level of the liquid solution in the agrochemical tank has not fallen below the set minimum. This operation is handled by a level transducer placed in the tank which sends its signal to the micro-controller, which evaluates its status. This transducer is corrosion- resistant and may potentially be non-invasive. 2. That the wind does not exceed the threshold set as the limit, which would cause excessive drift of the spray, resulting in lower efficiency and environmental damage.

3. If the ambient temperature falls below levels approaching the freezing point of the solution, which would damage the entire system. On the other hand, excessive temperatures cause the rapid evaporation of the solution prior to impacting the target area. The above condition is aggravated if the relative humidity is low.

4. Relative humidity. This variable has a harmful effect in the event of high temperatures and a small-drop spray spectrum, since these drops evaporate quickly.

5. Pump station operating pressure. This is sensed at two points, the first is before the pressure-regulating valve to evaluate the proper operation of the pump, and the second is after the aforementioned valve, providing information on the operation of the distribution system. 6. Voltage level. This is sensed in the movement systems which use electric energy since this variable determines the rotation speed of the motors driving the towers, and may therefore influence the dosage applied.

The complete pump station installation is rust-proof. This is achieved by galvanizing the whole chassis supporting the valves and the pump. In addition, the valves are made of a plastic material resistant to ultraviolet and infrared light. The pump is entirely made of stainless steel and all connections are made of weather resistant polymers.

Both the pressure-regulating valve and the pressure-sustaining valve are hydraulically controlled, which means that they require no energy to operate other than that provided by the pressure of the liquid solution.

The features of the pump in terms of flow rate and pressure are as follows:

1. The necessary flow rate which the pump must be able to provide at all times will be the sum of two flow rates, the first being that determined by the instantaneous need of the various subsections into which the equipment is divided, and the second is that which is necessary to agitate the solution remaining in the tank using a jet agitator, which at no time should be allowed to settle, since if it did, the concentration would increase as the agrochemical is consumed. The instantaneous flow rate will increase as the selected dosages increase and the speed of the irrigation equipment increases.

2. The pressure to be supplied by the pump is that required for the operation of all of the spray nozzles and that necessary to drive the jet agitator. In order to achieve this pressure, it is necessary to know the pressure loss existing on the distribution line when the required flow rate is at its maximum. Therefore it has been calculated based on the type of material used in the line, the existing connections and the diameter used.

Distribution Line for the Solution to be Applied

The distribution line is made of high-density polyethylene, with quick-connect couplings and diameters that vary according to the features of each particular case. The advantages of high-density polyethylene (HDPE) is that it is not affected by the corrosive products it must normally carry and is easy to handle compared to other types of polymers used in distribution lines. The HDPE itself is not affected by the ultraviolet or infrared light to which the system will be exposed. The main line carries the solution the entire length of the equipment, and from it branch all the secondary lines which supply the solution to the nozzles in each section. For this purpose and for each secondary line, there is an electrically-operated valve activated from the control system mounted on the equipment's tower by the micro-controller. The main line and the secondary lines must withstand the operating pressure of the nozzles, and for this reason their specifications are determined by the nozzles' pressure ranges, to which the load loss on the line will be added.

The distribution line is designed based on the flow rate at which it must distribute the solution and the pressure at which the solution is to arrive. In other words, by knowing the instantaneous flow rate at which the solution is to arrive at the various subsections, I mathematically obtain the loss of pressure on the distribution line (load loss) if I select a specific section. The final choice, is made based on the cost of the line, which increases exponentially with diameter and proportionally with the pressure required in the pump station. The distribution line is divided into two parts, one called the main line which distributes the solution over the entire length of the irrigation equipment. This line is mounted on the struts which support the irrigation equipment's piping with clamps and straps. All of the branches which come off this line are quick-connect couplings permitting a rapid and accurate setup. The secondary lines branch off the main line and comprise each subsection into which each section of the irrigation equipment is divided.

At the start of each secondary line, there is a direct-action pressure regulator which is externally controlled and which permits the secondary line to be isolated from potential main line pressure fluctuations. This regulator also has the function of varying the pressure at which the boom of nozzles comprising the secondary line will operate; this pressure must be variable in order to operate the nozzles at the various points of the curve which characterizes them and which correspond to different drop-size spectrums, based on the requirements of each particular agrochemical.

After the regulator there is an electrically-operated solenoid pilot valve, which is activated and deactivated by the micro-controller that controls that subsection and the others comprising the section. This electrically-operated valve is made of corrosion- resistant material and has a solenoid device which opens and closes the valve. The electrically-operated valve has a diaphragm which blocks the passage of the solution, except when the solenoid allows it to pass. The energy activating the solenoid comes from the control panel mounted on the section tower, which also contains the micro-controller and all of the section's control logic.

The nozzles which perform the spraying are mounted on the secondary line.

Nozzles

The next step is to describe the nozzles which meet the following conditions: 1. They are low flow rate nozzles, allowing correct pluviometry and reduced deposit. 2. They allow proper coverage at any stage of crop growth.

3. They work in medium pressure ranges, thereby allowing the use of the full range of pest control and fertilizer products in solution.

4. They are of excellent quality for use under extreme conditions.

5. They have the highest possible spraying area, thereby reducing the number of nozzles per section.

6. They allow a high degree of uniformity in agrochemical application.

7. They reduce drift to a minimum.

8. Excellent distribution over a wide range of pressures.

9. They are commonly used in agriculture and are adequately stocked.

Spray Angle and Coverage Level

Depending on the type and size of the nozzle, the operating pressure may have a considerable influence on the spray angle and the quality of distribution. Lower pressure is associated with a smaller spray angle and a significant reduction in coverage. It is important to be sure to work with the spray points within the indicated pressure range.

Spraying with liquids which have densities higher than water results in relatively naiTOwer spray angles, while liquids with surface tensions lower than that of water produce wider spray angles.

Drift and Drop Size

Drift may be defined as the delivery of drops outside the desired target area. This phenomenon constitutes one of the most significant environmentally-related problems facing the user of the sprayer. In order to ensure the proper selection of nozzles and applications, the user must know the drop size.

The spray profile of a nozzle is composed of a large number of drops of varying sizes. Drop size is understood as the size of a single drop. Since most nozzles have different drop sizes, a statistical analysis has been established.

Drop size is usually expressed in microns (micrometers). One micron is equivalent to 0.001 mm. The micron is an appropriate unit of measure because it is so small, allowing for the expression of drop size in whole numbers. Drop size is expressed in microns, and median volumetric diameter (vD0.5) is a common term used to express drop size. The vD0.5 is the value of the diameter of the drops, composed of 50% of the volume of drops of larger- than- average size and 50% of smaller-than-average drops. A nozzle with a large vD0.5 is usually selected to reduce drift, while a nozzle with a reduced vD0.5 is required for maximum plant coverage. Since the vD0.5 does not provide a complete picture of the distribution of the drops from a specific nozzle, this value must be used with caution when selecting a nozzle.

One aspect of drop size useful for determining the potential drift of a nozzle is the percentage of drops which tend to drift. Since smaller drops have a greater tendency to drift, it is advisable to establish the percentage of small drops from a specific nozzle, in order to minimize it when drift is a problem. Drops smaller than 200 microns are considered to potentially contribute to drift.

A small-drop nozzle is usually recommended for post-emergence applications which require excellent leaf surface coverage.

Flow Rate

The flow rate of the nozzle varies according to the spray pressure. In general, the ratio between 1/min. and the pressure is as follows: l/minl/l/min2 = barl(l/2)/bar2(l/2)

This equation implies that in order to double the flow rate through one nozzle, the pressure must be quadrupled.

Higher pressure not only increases the flow rate of the nozzle, but also influences the size of the drops and the wear on the orifices. FL-Fulljet (Spraying Systems Co.)

Frequently, nozzles are selected according to the drop size required. Drop size will constitute a critical factor when the efficacy of a specific chemical product applied to the crop depends on the degree of coverage, or when the priority is to prevent the spraying of liquid outside the application area.

Most nozzles used in agriculture can be classified as producing fine, medium or thick drops. Nozzles producing fine drops are usually recommended for post-emergence applications, which require excellent coverage on leaf surfaces. The most common nozzles in agriculture are those which produce medium-sized drops. These nozzles may be used with contact and systemic herbicides, pre-emergence, surface-applied herbicides, insecticides, fungicides and fertilizers in solution.

One aspect to consider when selecting a spray nozzle is that it should produce a drop size in one of these three categories based on the pressure that exists when the pulse is triggered.

The FL-Fulljet nozzle manufactured by Spraying Systems Co. has this feature; at pressures of 1 - 1.5 bar it supplies a medium to large-sized drop spectrum and between 1.5 - 3 bar, a medium to small size.

The Fulljet spray spectrum is a "full cone" spectrum, which is ideal for: • Herbicides added to the soil.

• Pre-emergent herbicides.

• Post-emergent, systemic herbicides

• Systemic fungicides.

• Systemic insecticides. • Fertilizers in solution.

The nozzles are mounted on the subsection that comprise the secondary line using a coupling, which includes a check valve that opens when the pressure exceeds a given value, which in this case is 0.7 bar. This prevents the residual solution from draining through the nozzle in the form of drops when the secondary line is inactive. In turn, since the line remains loaded with the remaining solution, there is no fill time prior to each pulse, thus increasing pulse efficiency. In order to prevent the nozzles from clogging with residual solution, each one has a filter, which is selected based on the size of the nozzle. The nozzle is mounted on the support using a quick-connect coupling for easy installation.

The Micro-Controller

The micro-controller used is part of the picl6f84 family of microchips in the towers, and the picl6c74 in the pump station. The first one is responsible for processing the various signals on the status of the irrigation equipment's towers, i.e., the direction of movement and the combination of the towers. It also makes the decisions based on its programming, taking into consideration the required spraying parameters, thus sending the activation signals that control the opening of the various electrically-operated valves in the different subsections.

Each irrigation tower has an associated circuit comprised of a contactor which is activated by a switch. This switch is controlled by a lever which is connected to the following section of the irrigation equipment and is activated when a determined angle has been swept. The contactor closes the power circuit for the motor on the tower, putting it in motion. This movement continues until the tower is aligned with the rest of the equipment, and at this point the contactor opens. Alignment controls are common and will not be described in detail. For example, See U.S. Patent Nos. 5,678,771 and 5,947,393. The micro-controller detects the movement of the tower in which it is installed and the movement of the preceding tower by means of the status of the contactors of each tower. If a contactor is closed, it indicates that that tower is moving, and when it is open, the tower has stopped. The signal from the preceding tower is received through a cable placed along the piping of the irrigation equipment for this purpose. As mentioned hereinabove, between the tower that contains the micro-controller and the preceding tower, there are three types of movement:

• Circular movement between the activated tower and the preceding stopped tower; this will be called positive movement (+).

• Linear movement of the entire section when both towers are activated, called linear movement.

• Circular movement between the preceding tower which is now activated and the stopped subsequent tower, called negative movement (-). This combination of movements is processed by the micro-controller and these movements, together with other parameters such as the surface area sprayed by each nozzle, the distance separating the nozzles on the secondary line, the drift due to the wind, etc., allow the micro-controller to decide when to spray.

The Micro-Controller Circuit Mounted on the Towers

In order to power the circuit, a voltage transformer is used to convert the 1 1 OV at which imgation equipment contactors normally operate to 24V. After the transformer, a diode bridge is used to rectify the alternating voltage. To reduce the remaining ripple, a low-pass filter is implemented by means of electrolyte capacitors and other lower capacity ceramic capacitors are used to filter high frequency components such as those produced by starting up the tower motors or those produced in the contactors when they are switching. The voltage must be reduced to 5 V to power the micro-controller and the rest of the components of the circuit. An integrated voltage regulator is attached for this purpose. This regulator allows for the drawing of a current of up to 1.5 A, which is sufficient to power the entire circuit. The micro-controller requires a clock to operate which is deployed with a piezoelectric crystal and two grounded capacitors. The signal indicating that the main tower, the tower with the micro-controller, is moving and the signal from the secondary tower (referring to the preceding tower) are taken from relays which close when the contactor associated with the aforementioned towers closes. When these relays close, they pull down the input from the micro-controller port programmed for this purpose. The action whereby a specific point on the circuit is grounded is called pull-down. The microcontroller thus detects that the tower is moving and determines the type of movement of the section in question. In order to regulate the dosage of solution per unit of area, a dip switch bank is mounted on the printed circuit, which by switching between two possible options can pull up the input from the micro-controller's I/O port, which is detected by it and duly evaluated to determine the duration of the spray pulse.

The quick-switching electrically-operated valves are controlled by relays activated through pins in the port of the micro-controller used for this purpose. Each subsection, mentioned before (which holds the nozzles), is activated by one electrically-operated valve, so the circuit will have as many output relays as subsections in the section the section associated with this tower and the micro-controller that controls it.

Since the micro-controller port has limitations with respect to output current, a current buffer is placed between it and the electrically-operated valve relay, which has the function of activating the relay with the current it uses and drawing the minimum current from the micro-controller port that is necessary for its operation.

The voltage used by the electrically-operated valves is not 5V, but rather a higher voltage, which comes from the transformer which powers the circuit and is delivered to the electrically-operated valve when the relay with which it is associated closes. Indicator lights with LEDs are placed on the circuit indicating:

1. When the main tower is moving.

2. When the secondary tower is moving.

3. Whether the micro-controller is operating properly.

4. When each section's electrically-operated valve has opened, meaning that subsection is applying the spray pulse.

The Micro-Controller Circuit Mounted on the Pump Station

In order to power the circuit, a voltage transformer is used to convert the 110 V at which the irrigation equipment panel normally operates to 24V. After the transformer, a diode bridge is used to rectify the alternating voltage. To reduce the remaining ripple, a filter is implemented with electrolyte capacitors and other ceramic capacitors are used to filter high frequency components such as those produced by starting up the tower motors, the pump or those produced in the contactors used when the current changes direction.

The voltage must be reduced to 5V to power the micro-controller and part of the circuit. An integrated voltage regulator is attached for this purpose. The amplifiers used in the signal conditioning are in turn powered by a split source, and for this reason another voltage regulator with negative output is included.

The micro-controller requires a clock to operate, which is deployed with a piezoelectric crystal and two grounded capacitors. The signal indicating that the tank is at its minimum level is taken from a corrosion-resistant level sensor with a relay output. When this relay closes it pulls down the input from the micro-controller port programmed for this purpose. This is how the micro-controller detects that the tank is empty and that it must stop the application.

Relative humidity is sensed by a resistive transducer which changes its impedance based on the ambient humidity. This sensor feeds into a comparator which performs a pull-up in the micro-controller port when an ambient humidity value set in the comparator is exceeded.

Ambient temperature is sensed by an NTC, which is an element which varies its resistance with changes in temperature. Since this element has a negative, nonlinear variation coefficient, the micro-controller detects the element's changes in terminal voltage through an analog-digital converter in a pin at its port A. Since this variation is nonlinear, a table has been added to the micro-controller's memory so it knows the real value of the ambient temperature.

Pump station pressure is sensed through a transducer which uses strain gages, using signal conditioning in such a way that the voltage variation is proportional to the pressure variation. This information is also input into an analog-digital converter in the microcontroller for processing.

The network voltage must be known by the micro-controller, because this will have a proportional impact on the speed of the tower motors. For this reason the voltage is rectified and a resistive divider is used to bring these values to a voltage under 5V which is the voltage used by the micro-controller as the highest value due to the programming of the analog-digital converters. Since the voltage obtained from the resistive divider has a ripple, it must be filtered, and a level two Bessel filter is used for this purpose.

Mounting and Fastening System The fastening system for the spraying equipment consists of a galvanized steel bar mounted in a perpendicular fashion on each tower, which is clamped to the pivot piping and the drive support. A galvanized steel cable is hung between each tower to support the secondary agrochemical distribution line on that section. This is hung parallel to the ground using fastening chains to achieve the required uniformity. It is equipped with tumbuckles which allow it to compensate for variations in the terrain and the section movements. And finally, the agrochemical distribution line is strapped to the galvanized steel cable for a quick, efficient installation. The complete assembly system allows the application height to be varied from 0.75 m to 2.9 m corresponding to the maximum clearance beneath the pivot's water distribution line.

Programming

In order to provide the control link, the micro-controller must be programmed to instruct it to perform these functions. The micro-controller programs for each tower comprising the irrigation equipment are similar, varying only in the number of electrically- operated valves controlled by each one. The program has a software-deployed clock and after having input the motor speed, it determines the type of movement of the section through the relays on the activated towers. Since it knows the speed at which the tower is moving and the type of movement involved, it calculates the instantaneous movement of each subsection making up the section between the tower with the micro-controller and the preceding tower. It is important to clarify that all towers have an active micro-controller and when the contactor on each tower closes, this will be detected by the micro-controller on that tower and on the next tower.

Each time a tower relay closes, it triggers a switch in the micro-controller, which indicates to the micro-controller that a status change has occurred in a specific pin in the port programmed for this purpose. There are two switches, one for each relay on the activated towers. When a switch signal occurs, the program modifies the type of movement controlling the subsections.

Since the type of nozzle used is also programmed, the micro-controller knows the surface area this type of nozzle is capable of spraying, and thus, by knowing the subsection's type of movement, it determines the time to emit the pulse. If we consider the surface area each nozzle is capable of spraying and add all the surface areas comprising the subsection, we have a strip capable of spraying an area calculated as a function of the height of the boom, the maximum considered wind limit, the operating pressure of the nozzle, and the overlapping between nozzles. The program then determines when to emit the next pulse as it passes over the subsection's spraying surface. The duration of the pulse determines the dosage per unit of surface area. To do this, the program consults the status of the port used for this purpose, which the operator modifies with the dip switches.

The programming of the pump station micro-controller has the analog-digital converters activated in the ports, and the program consults these converters on a cyclical basis to determine the status of the various signals delivered by the transducers placed at the various sensing points. When one of the variables exceeds the level programmed as correct, an alarm signal is triggered and the agrochemical application system stops along with the irrigation equipment. If the wind or another expressly programmed factor triggers the alarm, the system offers the option of restarting when the variable returns to acceptable levels.

Pump Station

The pump station is comprised of a centrifugal pump whose capacity will vary for each particular type of equipment, which extracts the solution from a tank containing the agrochemical to be applied; this pump is called Bl {Centrifugal Pump} in the drawing. The pump and the tank are connected by means of a suction line LI which includes a spherical valve VI to cut off the supply if necessary, and a filter FI {Filter 1} to prevent the passage of sediment into the blades of the impulse turbine. At the pump outlet there is another mesh filter F2 {Filter 2} which has the function of preventing any foreign matter not trapped by the first filter from passing into the main line.

The tank is agitated by the same pump using a jet agitator AG 1 connected to the system through a pressure-sustaining valve V2 {Sustaining Valve} mounted in parallel with the main line L2 {Main Line}, which shunts the unused fluid and allows a constant given pressure to be maintained. The main line which carries the solution to the spray nozzles has a serially connected pressure-regulating valve V3 {Regulating \ alve} which allows a constant pressure to be maintained in the event of flow rate fluctuations produced by the opening of the various spray bars placed on the sections of the irrigation equipment. In turn, the system has two pressure sensors, one before the pressure-sustaining valve P S 01 which verifies the status of the pump and triggers a high pressure alarm signal; and the other after the pressure-regulating valve P S 02, which evaluates the correct operation of the pump station. A pressure gauge M 1 {Pressure Gauge} is included to view the pressure, which is mounted on a three-way selector to inspect different selected points.

Distribution Line The distribution line is divided into two parts, one called the main line, which distributes the solution along the entire length of the irrigation equipment. This line is mounted on the struts which support the irrigation equipment's piping using clamps and straps. All of the branches which come off this line are quick-connect couplings which allow a rapid and accurate setup. The secondary lines branch off the main line and comprise each subsection into which each section of the irrigation equipment is divided. The distribution line is made of high-density polyethylene, with quick-connect couplings and diameters that vary based on the features of each particular case. The main line carries the solution the entire length of the equipment, and from it branch all the secondary lines L3 {Secondary Line} which supply the solution to the nozzles in each section. For this purpose and, for each secondary line, there is an electrically-operated valve V3 {Electrically-Operated Valve} activated from the control system mounted on the equipment's tower by the micro-controller.

At the start of each secondary line is a direct-action pressure regulator RO {Pressure Regulator} which is externally controlled and which allows the secondary line to be isolated from potential main line pressure fluctuations. This regulator also has the function of varying the pressure at which the boom of nozzles comprising the secondary line will operate; this pressure must be variable in order to operate the nozzles at the various points of the curve which characterizes them and which correspond to different drop-size spectrums, based on the requirements of each particular agrochemical. After the regulator there is an electrically-operated solenoid pilot valve V3, which is activated and deactivated by the micro-controller that controls that subsection and the others comprising the section. This electrically-operated valve is made of corrosion- resistant material and has a solenoid device which opens and closes the valve. The electrically-operated valve has a diaphragm which blocks the passage of the solution, except when the solenoid allows it to pass. The energy activating the solenoid comes from the control panel PI {Main Panel} mounted on the section tower, which also contains the micro-controller and all of the section's control logic . The nozzles BXX {Nozzles} which perform the spraying are mounted on the secondary line.

The Micro-Controller Circuit Mounted on the Towers In order to power the micro-controller circuit Ul {Picl6C84-04/P}, a voltage transformer is used to convert the 1 10V at which irrigation equipment contactors normally operate to 24V; on the schematic, this transformer is referenced as TRANS1 {TRANS F.(U0v/24V)}. After the transformer, a diode bridge, referenced as C2 {BRLDGEl}, is used to rectify the alternating voltage. To reduce the remaining ripple, a low-pass filter is implemented by means of electrolyte capacitors and other lower capacity ceramic capacitors are used to filter high frequency components such as those produced by starting up the tower motors or those produced in the contactors when they are switching; these capacitors are Cl {2200μF}, U6 {O.lμF}, U7 {O.lμF}, C3 {WOμF}. The voltage must be reduced to 5 V to power the micro-controller and the rest of the components of the circuit. An integrated voltage regulator referenced as U5 {LM7805CT} is attached for this purpose. This regulator allows for the drawing of a current of up to 1.5 A, which is sufficient to power the entire circuit. The micro-controller requires a clock to operate, which is deployed with a piezoelectric crystal and two grounded capacitors, referenced as U2 {3 M/tz}, U3 {15μF} and U4 {15μF}, respectively. A reset circuit is implemented in turn, which is required to reset the micro-controller functions; this is done with the S4

{Reset} and the associated circuit. The signal indicating that the main tower (as I will now call the tower with the micro-controller) is moving and the signal from the second tower (referring to the preceding tower) are taken from relays C8 {Main Tower} and C7 {Second Tower} which close when the contactor associated with the aforementioned towers closes. When these relays close, they pull down the input from the micro-controller port programmed for this purpose. The action whereby a specific point on the circuit is grounded is called pull-down. The micro-controller thus detects that the tower is moving and determines the type of movement of the section in question.

In order to regulate the dosage of solution per unit of surface area, a dip switch bank SW5 {SW-DIP4} is mounted on the printed circuit, which by switching between two possible options can pull up the input from the micro-controller's I/O port, which is detected by it and duly evaluated to determine the duration of the spray pulse. The quick-switching electrically-operated valves are controlled by relays C4 {Subsection 1}, C5 {Subsection2} and C6 {SubsectionS} activated through pins in the micro-controller port used for this purpose. Each subsection, as I mentioned before (which holds the nozzles), is activated by one electrically-operated valve, so the circuit will have as many output relays as subsections in the section associated with this tower and the micro-controller it controls.

Since the micro-controller port has limitations with respect to output current, between it and the electrically-operated valve relay there is a current buffer U8A, U8B and U8C {BUFFER}, which has the function of activating the relay with the current it uses and drawing the minimum current from the micro-controller port that is necessary for its operation.

The voltage used by the electrically-operated valves is not 5V, but rather a higher voltage, which comes from the transformer that powers the circuit and is delivered to the electrically-operated valve when the relay with which it is associated closes. This transformer is called TRANS2 {TRANSF.(24V/U0V)}.

Indicator lights with LEDs are placed on the circuit indicating:

5. When the main tower is moving S6 {Main Tower On}.

6. When the secondary tower is moving S7 {Secondary Tower On}. 1. Whether the micro-controller is operating properly S5 {On}. 8. When each section's electrically-operated valve has opened, meaning that subsection is applying the spray pulse XI 1 {Subsection I on}, X9 {Subsection 2 on} and XI 0 {Subsection 3 on}.

Thus it can be seen that the invention accomplishes at least all of its stated objectives.

Claims

I claim:

1. An agrochemical application system for irrigation equipment characterized by applying agrochemicals to crops within the coverage area of irrigation equipment, whether central pivot or forward advancing equipment, regardless of its manufacturing origin, in a precise and efficient manner in which the application is carried out by means of short- duration pulses of the liquid solution onto the surface of the crops, said crops being in any stage of growth, since the system may vary its operating height up to the maximum clearance existing between the plane of application and the imgation equipment structure, the innovative part of the invention being the control link which controls the time the pulses are emitted, handled by a micro-controller, which makes decisions by sensing, through the status of the contactors on the motors of the towers which drive the irrigation equipment structure, the type of movement of the section between the tower bearing the micro-controller and the preceding tower, said section being divided in turn into other sections of shorter length which hold the nozzles that perform the spraying, the duration of the liquid solution pulses being part of the innovative aspect of this invention, since it may vary as a function of the dosage required by the type of agrochemical, which shall be selected by the user and stored in the micro-controller, with higher dosages requiring longer pulses.

2. An agrochemical application system for irrigation equipment in accordance with claim 1 which is characterized by having a control link which is placed in a microcontroller which uses the voltage signals that close the contactors of the tower on which it is mounted and the preceding tower in order to establish the type of movement of the section of the irrigation equipment by knowing the type of movement and having input the speed of the motors in advance, then calculates the speed of each subsection into which the aforementioned section is divided, and determines the time to emit the pulse of solution, this pulse being applied by the nozzles located on the subsection which in turn draws the agrochemical solution from the main line through a pressure regulator and a quick- switching electrically-operated valve, both activated by the micro-controller at the time of the pulse, with the time the pulse is applied being a function of the characteristics of the nozzles and the separation thereof within the subsection, information which is also provided to the micro-controller during programming.

3. An agrochemical application system for irrigation equipment in accordance with claim 2 which is characterized by a pump station which is able to maintain a constant pressure, even when there are flow rate variations in the system due to the activation of the various subsections which perform the spraying on the crops, said station being able in turn to shunt a percentage of its flow rate to the tank, thus allowing the remaining agrochemical to remain in the tank at uniform levels of concentration, with a pipeline to carry the liquid solution to the nozzles, said line being resistant to corrosion and environmental conditions, and divided into two distinct parts, a so-called main line and a secondary line, the main line being responsible for carrying the agrochemical along the length of the irrigation equipment, and the secondary line, which will be multiple, used to spray the agrochemical through the nozzles mounted thereupon.

4. In combination: a center pivot structure; a main water distribution line extending outwardly from said center pivot structure; a plurality of spaced-apart, electrically driven drive towers supporting said main water distribution line above the ground which propel the main water distribution line over the area to be irrigated; an electric motor on each of said drive towers for driving drive wheels thereon; an alignment control one each of said drive towers, except for the outermost tower, which controls the activation of the associated drive motor; a main chemical distribution line extending along the length of the main water distribution line; a secondary chemical distribution line positioned between each of said drive towers which is positioned below said main water distribution line and which is in fluid communication therewith; each of said secondary chemical distribution lines being comprised of one or more individual secondary line sections; spaced-apart spray nozzles mounted on said secondary line sections; a branch line extending from said secondary chemical distribution line to each of said secondary line sections; an electrical controlled valve imposed in each of said branch lines; said main chemical distribution line being in communication with a source of liquid chemical under pressure; a programmed micro-controller mounted on each of said drive towers, except for the outermost drive tower, for controlling the operation of the valves imposed in the branch lines associated with the secondary line sections of that drive tower; said micro-controller being operativelv electrically connected to the alignment control on that drive tower and being electrically connected to the alignment control on the drive tower positioned inwardly thereof; said micro-controller sensing the movement of the associated drive tower and the drive tower positioned inwardly thereof to control the operation of the said valves.

5. The combination of claim 4 wherein the source of liquid chemical under pressure comprises a pump station including a chemical supply tank; said pump station including a micro-controller which is electrically connected to each of said micro-controllers on said drive towers.

6. The combination of claim 5 wherein said pump station micro-controller is operatively connected to a sensor which senses the level of chemical in said supply tank.

7. The combination of claim 5 wherein said pump station micro-controller is operatively connected to a wind velocity sensor.

8. The combination of claim 5 wherein said pump station micro-controller is operatively connected to an ambient temperature sensor.

9. The combination of claim 5 wherein said pump station micro-controller is operatively connected to a relative humidity sensor.

10. The combination of claim 5 wherein said pump station micro-controller is operatively connected to a pump operating pressure sensor.

1 1. The combination of claim 5 wherein said pump station micro-controller is operatively connected to a system voltage sensor.

12. The combination of claim 5 wherein said pump station micro-controller is operatively connected to a sensor which senses the direction of movement of the drive towers.

13. In combination: a linear irrigation system having an elongated main water distribution line supported upon spaced-apart drive towers which propel the main water distribution line over the area to be irrigated; an electric motor on each of said drive towers for driving drive wheels thereon; an alignment control one each of said drive towers which controls the activation of the associated drive motor; a main chemical distribution line extending along the length of the main water distribution line; a secondary chemical distribution line positioned between each of said drive towers which is positioned below said main water distribution line and which is in fluid communication therewith; each of said secondary chemical distribution lines being comprised of one or more individual secondary line sections; spaced-apart spray nozzles mounted on said secondary line sections; a branch line extending from said secondary chemical distribution line to each of said secondary line sections; an electrical controlled valve imposed in each of said branch lines; said main chemical distribution line being in communication with a source of liquid chemical under pressure; a programmed micro-controller mounted on each of said drive towers for controlling the operation of the valves imposed in the branch lines associated with the secondary line sections of that drive tower; said micro-controller being operatively electrically connected to the alignment control on that drive tower and being electrically connected to the alignment control on the drive tower positioned inwardly thereof; said micro-controller sensing the movement of the associated drive tower to control the operation of the said valves.

14. The combination of claim 13 wherein the source of liquid chemical under pressure comprises a pump station including a chemical supply tank; said pump station including a micro-controller which is electrically connected to each of said micro-controllers on said drive towers.

15. The combination of claim 14 wherein said pump station micro-controller is operatively connected to a sensor which senses the level of chemical in said supply tank.

16. The combination of claim 14 wherein said pump station micro-controller is operatively connected to a wind velocity sensor.

17. The combination of claim 14 wherein said pump station micro-controller is operatively connected to an ambient temperature sensor.

18. The combination of claim 14 wherein said pump station micro-controller is operatively connected to a relative humidity sensor.

19. The combination of claim 14 wherein said pump station micro-controller is operatively connected to a pump operating pressure sensor.