Fluid sprinkling – spraying – and diffusing – Mobile distributor – Irrigation device
Reexamination Certificate
1999-12-16
2001-07-03
Bagnell, David (Department: 3673)
Fluid sprinkling, spraying, and diffusing
Mobile distributor
Irrigation device
C239S733000, C239S069000, C701S050000, C701S215000
Reexamination Certificate
active
06254018
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a center pivot irrigation system and more particularly to an alignment control for long center pivot systems.
2. Description of the Related Art
Conventional center pivot irrigation systems comprise an elongated water pipe pivotally connected at its inner end to a center pivot structure and extending outwardly therefrom. The water pipe of the conventional center pivot system is comprised of a plurality of pipes connected together in an end-to-end fashion which are supported upon a plurality of drive units. Each of the drive units may be propelled by an electric motor, a hydraulic motor or an air motor, with electric motors being the most popular and widely used source of propulsion. Normally, the outermost drive unit or last drive unit is the master unit with the other drive units being selectively driven in response to angular displacement of the pipe section adjacent thereto.
The machine alignment on the center pivot system is maintained by a mechanical linkage at each drive unit span joint, which operates a micro-switch, which in turn starts and stops the electric motor on the drive unit to keep it alignment with the next span. The alignment control works well on most machines, up to approximately 1,500 feet in length, but does not always maintain good alignment on longer systems. The reason for the problem on long systems is that small changes in alignment at a number of drive units on the system can cause a large change in the overall system alignment. If the alignment gets bad enough, it can cause structural damage to the system. These small changes in alignment are causes by external forces such as the drive unit crossing crop furrows at an angle, strong wind blowing on the spans, or temperature changes in the micro-switches and linkages.
SUMMARY OF THE INVENTION
An alignment control is provided for long center pivot systems having an elongated water pipe extending outwardly from a center pivot structure with the water pipe being supported upon a plurality of drive units which propel the water pipe around the center pivot structure. Each of the drive units includes a drive means such as an electric motor which is actuated by a mechanical linkage at each drive unit span joint, which operates a micro-switch, which in turn starts and stops the electric motor on the drive unit to keep it in line with the next span. A first GPS control is provided at the center pivot structure which functions as a stationary reference. A second GPS control is positioned on the center drive unit near the center length of the water pipe. A third GPS control is mounted on the outermost or last drive unit. A computer-operated control system is operatively connected to the center drive unit where the second GPS control is located. The first, second and third GPS controls are operatively connected to the computer-operated control system. The computer-operated control system computes an approximate straight line between the center pivot structure and the last drive unit and selectively operates the drive means on the center drive unit so that the center drive unit will be positioned or maintained within some tolerance of the approximate straight line between the center pivot structure and the last drive unit. The computer-operated control system may continuously compute the approximate straight line or periodically compute the approximate straight line. As stated, the center drive unit includes an alignment control which normally controls the movement of the center drive unit. The computer-operated control system may override the alignment control on the center drive unit when the position of the center drive unit exceeds some tolerance from the approximate straight line. The irrigation system may further include a system control for stopping all of the drive units when the last drive unit has reached the predetermined position. The irrigation system may further include a system control for reversing the direction of the irrigation system when the last drive unit has reached a predetermined position in the field. Further, the irrigation system may include a selectively operable end gun sprinkler at the outer end of the water pipe which is actuated when the last drive unit reaches a predetermined position in the field and which deactuates the end gun sprinkler when the last drive unit has reached a particular position in the field.
It is therefore a principal object of the invention to provide an improved alignment control for long center pivot irrigation systems.
Still another object of the invention is to provide an alignment control for long center pivot irrigation systems wherein a first GPS control is mounted on the pivot point as a stationary reference, a second GPS control is mounted on the last drive unit, and a third GPS control is mounted on a drive unit near the center of the system, and wherein the GPS controls and associated computer controls continuously or periodically compute a straight line between the pivot point and the last drive unit with the control system operating the drive unit near the center of the system so that it stays within some tolerance of the straight line between the pivot and the last drive unit.
Still another object of the invention is to provide an alignment control for long center pivot irrigation systems which may control the drive unit near the center of the system all the time or which may be used to override the standard alignment when the position of the center drive unit exceeds some tolerance from the straight line.
Still another object of the invention is to provide an alignment control for long center pivot irrigation systems which provides the added benefit of always knowing the exact position of the last drive unit for controlling such things as end guns, changing directions, or stopping the machine.
These other objects will be apparent to those skilled in the art.
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Bagnell David
Singh Sunil
Thomte Dennis L.
Valmont Industries, Inc.
Zarley McKee Thomte Voorhees & Sease
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