" LIQUID APPLICATION SYSTEM FOR CENTER PIVOT IRRIGATION SYSTEMS "

1. BACKGROUND OF THE INVENTION

The present invention refers to a Low flow liquid application system for center pivot irrigation systems, for applications requiring low volumes of water, as chemical treatments.

The invention consists of adapting to the pivot independent pipes with micro-sprinklers having different distances between them, according to calculation to make case the case to obtain the correct distribution and application uniformity.

The micro-sprinklers are installed with growing spacing, from the pivot's end to its center, and may have constant or variable values of water flow.

When this space becomes theoretical bigger than the maximum allowed, attending to the need to keep a good coverage of each micro-sprinkler' s debit, it will be installed a temporization

system, reducing the effective flow and allowing the reduction of that distances.

2. STATE-OF-THE-ART

Actually this kind of applications is made with aerial means, with tractor-mounted micro-sprinklers, directly trough the pivot's irrigation water or by means of other pivot-mounted systems .

The applications by aerial means are being restricted due to its costs and associated ecological risks.

The tractor-mounted micro-sprinklers applications are very limited by the soil conditions, becoming many times impossible, and produce a partial destruction of the installed crops.

The direct applications through the pivot's irrigation water requires the use of very high amounts of water, that are not desired in many seasons and incompatible with many products because of the very high resulting dissolution degree for them. Meanwhile many of these products are chemically aggressive for the pivot's structure, reducing its useful life.

Other pivot-mounted systems are very expensive and not very trustful, in terms of maintenance or efficiency.

They are usually based in micro-sprinklers installed at fixed distances, looking to achieving the distribution uniformity by an increase of the flow provided for each spray, as they are even further from the center of the system.

This flow control is very complex especially in low flow systems; it is conditioned by the difficulty to find proper equipment with the required rigor, and has not yet been properly solved.

Among the systems of the previous technique we'll next refer some documents however not based on the growing spacing between sprays, from the pivot's end to its center. Among them, we refer patent FR2659829, US5246164, and DE10154470

Patent FR2659829 refers to a rotating circular micro- sprinkler system for watering crops and applying pesticides . The system consists in a frame in sections on wheeled supports, rotating about a central fixed tower. The frame carries a main feed pipe, which is connected to the spray bar by a series of vertical branches one for each section, incorporating a pressure regulator and electrically .operated-valve. Each valve is linked in parallel with the drive motor of the corresponding section's wheeled support so that the valve closes and shuts off the feed to the spray bar every time the micro-sprinkler stops. A horizontal cable, to which clips connect it at intervals,

supports the spray bar and it has tensioners at its ends to maintain its horizontal position.

Patent US5246164 refers to an irrigation system having a number of micro-sprinklers in a fixed array each other, which are pivotally rotatable about a central tower or linearly movable along the length of a field, on a wheel line system or in a fixed solid lattice grid of a micro-sprinkler pipe. A solenoid-operated valve from a control module that is connected to a data acquisition and control unit, which activates or deactivates each individual micro-sprinkler head, independently controls each micro-sprinkler. A microprocessor receives data from micro- sprinkler line position sensors, ground speed sensors and micro- sprinkler line pressure sensors, and is programmed to determine the current position of each individual micro-sprinkler. The microprocessor generates maps from the field data or digital images, and the map positions, corresponding to current micro- sprinkler positions, are tested to determine water or chemical application requirements. The test data is then input by the microprocessor to the data acquisition and control system, which in turn sends signals to the micro-sprinkler control modules.

Patent DE10154470 refers to an irrigation device, especially for irrigating agricultural areas, that comprises a chassis supporting an extension arm protruding an equal distance over both sides of the chassis and provided at each end with a micro-

sprinkler coupled to a water supply line. Each micro-sprinkler has al least two discharge nozzles arranged the same distance from the axis of rotation of the micro-sprinkler and the same angle. The discharge nozzles are directed in a tangential position to the axis of rotation. The position of each discharge nozzle is variable. Each discharge nozzle is fixed via a flange on a micro-sprinkler head rotating about the axis of rotation. This irrigation device is used for the irrigation of agricultural areas. The irrigation device has a relatively simple construction guaranteeing ecological and economical irrigation.

As we can see none of the referred documents anticipates the object of this invention. In fact none of that documents refers a growing spacing between the sprays, which will allow the use of a constant flow at any spray.

3. DESCRIPTION OF DRAWINGS

^' The following description is based on the annex figures that, without any limitative feature, represent

Drawing n° 1: schematically, a center pivot and the system's installation way for the Low flow liquid application system.

Drawing n° 2: detail of the linking between the system's pipes and the pivot's vertical pipe.

Drawing n° 3 : detail of the positioning of the pressure regulation systems, the pressure indicator and the manual and automatic valves.

4. DESCRIPTION OF THE INVENTION

The base of the invention is the use of low flow and cost sprays (1) installed on a distribution pipe (2) suspended to the pivot at variable distances from each other (3), to compute for each pivot.

These sprays (1) can be of uniform flow, helping his choice and his installation. If required by the ground topography, they may include flow compensation system, so that the flow is constant regardless the inlet pressures.

The distribution pipe (2) is fed in various points from the main feeding pipe (4) , disposing at that points pressure regulation systems (5) , pressure indicators (6) and manual or automatic valves (7) allowing to intersect the distribution pipe when the application in some parts is not desired.

The feeding pipe (4) is connected to the pivot's vertical pipe (8) , from where receives the water, after proper manual or automatic filtering (9) .

The inlet of chemical products is made after this filter by means of a dosing pump (10) , being required the installation of an anti return valve (11) avoiding the chemical flow upwards.

At the distribution pipe's sections where the spray's working must be time controlled, acts a solenoid valve (12) controlled by a timer relays (13) installed for instance at the pivot's control panel (14) .

So the system uses the pivot's electrical and water supplies, as most of its existing security systems, being installed a valve (15) avoiding water entrance to the pivot.

The pivot's pumping system can be used to feed this system if it is installed a pressure control system as a reducing pressure valve or a flow return by-pass, or other pump control system as a motor speed controller.

It may also be installed a specific pump group for this low flow system.

The ' distribution pipe can be installed at a fixed or variable high to the ground, adapting to the existing crops, and the chemical products application can be _# restricted separating same of its sections, allowing cost and ecological risk reductions.