US 4,303,203 A · Center pivot irrigation system having a pressure sensitive drive apparatus

Abstract

A center pivot irrigation system includes an irrigation line supported by towers and rotatable about a central pivot. One tower thereof, for example the outermost tower, includes a drive motor energized in response to a signal from a pressure responsive control apparatus. The control apparatus is operable to sense the magnitude of the water pressure at a selected location in the line and therefore to sense decreases in such water pressure when the line travels uphill and increases in the pressure when the line travels downhill. The control apparatus produces a signal responsive to the sensed pressure which causes the drive motor to move the line at a rate inversely related to the average relative elevation of the line. That is, at faster rates of travel when the elevation of the line is below a reference elevation and at lower rates of travel when the elevation of the line is above the reference elevation to thereby prevent underwatering of uphill slopes and overwatering of downhill slopes. The selected location is preferably an equal area location such that the area traversed by the portion of the line from the pivot to the selected location is equal to the area traversed by the portion of the line from the selected location to its end. Thus, the sensed pressure is representative of the pressure at the equal area location.

Claims29

Dependent claims

A drive motor control apparatus for a center pivot irrigation line having plural towers, a drive motor at a lead one of such towers and a timer for periodically transmitting a control signal to the drive motor, the drive motor being energized in response to the control signal so as to move the line about its pivot for the duration of the control signal, comprising:

means for interrupting the transmission of the control signal from the timer to the drive motor at the lead tower;
control signal generator means for generating a replacement control signal of a duration which varies with variations in the magnitude of pressure in the line at a preselected location;
means for transmitting said replacement control signal to the drive motor so that the drive motor moves the line about its pivot for the duration of the replacement control signal.

A drive apparatus for moving a lead tower of a center pivot irrigation line and thereby follower towers and the line about its pivot whose relative elevation is zero comprising:

drive means for moving the lead tower about the pivot;
control means for controlling said drive means, said control means being responsive to the magnitude of water pressure sensed in the line at a location spaced from the pivot relative to the magnitude of a predetermined reference water pressure the magnitude of water pressure at such spaced location being lower when the spaced location is at an elevation higher than the elevation of the pivot and higher when the spaced location is at an elevation lower than the elevation of the pivot, said control means controlling said drive means to move the lead tower about the pivot at a slower rate of travel when the spaced location is at a higher elevation relative to the elevation of the pivot and for moving the lead tower about the pivot at a faster rate of travel when the spaced location is at a lower elevation relative to the elevation of the pivot.

An apparatus for controlling the energizing of a drive motor of a lead tower of a center pivot irrigation line to control the rate of travel of the lead tower and thereby follower towers and the line about its pivot comprising:

sensing means for sensing water pressure in the line at a predetermined location;
timer means for generating periodic timing signals, each such timing signal being of a predetermined duration which comprises a portion of an associated time interval of a series of successive time intervals, such time intervals also being of a predetermined duration;
control means responsive to said sensing means and to said timing signals for energizing the drive motor during an energization time subinterval of each such time interval, said control means comprising means for energizing the drive motor for one energizing time subinterval when the sensed pressure is at one magnitude, and for energizing the drive motor for a shorter energization time subinterval when the sensed pressure is at a lower magnitude.

A drive motor control apparatus for a center pivot irrigation line having plural towers, a drive motor at one of such towers and a timer for periodically transmitting a control signal to the drive motor, the drive motor bring energized in response to the control signal so as to move the line about its pivot for the duration of the control signal, comprising;

means for interrupting the transmission of the control signal to the drive motor;
control signal generator means for generating a replacement control signal of a duration which varies with variations in the magnitude of pressure in the line at a preselected location;
means for transmitting said replacement control signal to the drive motor so that the drive motor moves the line about its pivot for the duration of the replacement control signal;
said control signal generator means comprising pressure transducer means for sensing the magnitude of water pressure in the line at the preselected location and for producing a sensed pressure signal representing the sensed water pressure magnitude, reference pressure signal generating means for generating a reference pressure signal representing a reference water pressure magnitude, and replacement control signal generator means coupled to said transducer means and to said reference pressure signal generating means for receiving the sensed pressure signal and the reference pressure signal and producing a replacement control signal of a duration which varies with variations in the sensed pressure signal relative to the reference pressure signal.

1 more element

Dependencies are inferred from the claim text.

Center pivot irrigation system having a pressure sensitive drive apparatus

Life of this patent

Center pivot irrigation system having a pressure sensitive drive apparatus

Life of this patent

Abstract

Claims29