Pivot move agricultural irrigation system with improved water distribution and sprinkler head utilized therewith

Claim 1

In a pivot move agricultural irrigation system for distributing a source of water under pressure onto a field made up of soil having the capability of receiving water without appreciable surface run-off at a relatively high average application rate when relatively dry and at a relatively low application rate when relatively saturated with water including elongated conduit means for receiving a source of water under pressure at one end and conveying the water under pressure in a generally horizontal direction toward the opposite end thereof, a series of step-by-step rotary sprinkler heads spaced longitudinally along said conduit means in communicating relation therewith for distributing water under pressure within said conduit means incrementally onto the field in step-by-step rotary fashion within overlapping individual pattern areas defining a predetermined sprinkler head pattern area having first and second portions disposed on opposite sides of said conduit means, and means for supporting said conduit means above and generally parallel with the surface of the field and for effecting an arcuate movement of said conduit means about an axis adjacent said one end thereof in a direction toward said first pattern area portion along a predetermiNed circular path in the field while said conduit means is communicated with a source of water under pressure to distribute the same onto the field through said series of sprinkler heads within a predetermined system pattern area substantially greater than said predetermined sprinkler head pattern area by progressively moving the position of said predetermined sprinkler head pattern area within said predetermined system pattern area in said direction, at least a plurality of said series of sprinkler heads adjacent the opposite end portion of said conduit means having means for distributing the water under pressure within the longitudinally adjacent portion of said conduit means to the first pattern area portion covered thereby with an average application rate which is higher than the average application rate in said second portion covered thereby by a ratio of the order of between 1.3 to 1 and 4.0 to 1 and with a variation in the application rate within the first pattern area portion covered thereby such that the distribution pattern increases rapidly adjacent the leading portion of the sprinkler head pattern area covered to an extent sufficient to insure that the maximum accumulated application rate is applied to the soil while in a relatively dry condition, thus minimizing the creation of appreciable surface run-off, the improvement which comprises said water distributing means in each of said plurality of sprinkler heads comprising a sprinkler body having an inlet and outlet means, means for mounting said sprinkler body for controlled rotational movement about a generally vertical axis with said inlet in communication with said conduit assembly, said outlet means being disposed to direct water under pressure communicated with said inlet in generally one direction upwardly and outwardly in generally symmetrical relation to a plane passing through the axis of rotation, means for effecting repeated operating cycles of said sprinkler body including an operative movement in one direction about its axis and a reverse movement in the opposite direction about its axis such that the water flowing through said outlet means will be applied to an individual pattern area including a semicircular portion disposed within the first portion of said sprinkler head pattern area and a remaining portion disposed within the second portion of said sprinkler head pattern area, said semi-circular portion including a central segmental area of an arcuate extent of the order of between 60* to 120*, said cycling means including an impulse arm pivotally mounted with respect to said sprinkler body for oscillatory movement and having a reactant element thereon, said impulse arm being normally biased into a limited position wherein said reactant element is disposed to engage a portion of the water flowing through said outlet means and having means thereon operable (1) in response to the energy of the water flowing from said outlet means engaged by said reactant element to move said arm through repeated oscillatory cycles each of which includes an impulse stroke wherein said reactant element leaves the flowing water and moves away from the latter in one direction and a return stroke wherein said reactant element moves in the opposite direction toward the flowing water and enters the latter, and (2) during each oscillatory cycle thereof to effect controlled incremental rotational movement of said sprinkler body in the direction of operative movement, the operating cycle being such that the arcuate extent of said operative movement during which the water flowing from said outlet means is distributed within the semi-cylindrical portion of said individual pattern area is greater than the arcuate extent of the operative movement during which the water flowing from said outlet means is distributed to the remaining portion of said individual pattern area so that during one cycle of operation said semi-circular portion receivEs a greater amount of water than said remaining portion by a ratio of the order of between 1.3 to 1 and 4.0 to 1, the frequency of said oscillatory cycles and the relative portion of the water flowing from said outlet means engaged by said reactant element being such that the water flowing from said outlet means during the operative movement is normally distributed with a distribution pattern which is maximum adjacent the periphery thereof and decreases toward the axis of said sprinkler, and means operable during the operative movement of each operating cycle for engaging the water flowing from said outlet means so as to modify the distribution throughout said pattern area except within said segmental area to a distribution pattern which is maximum adjacent the axis of the sprinkler body and decreases toward the periphery.