Center pivot agricultural irrigation machines commonly include a main pipeline supported at intervals on movable towers for rotation about a fixed, center point proximate to an inner, proximal end of the pipeline. Irrigation fluid is supplied to the proximal end of the pipeline and distributed through sprinklers or other fluid emitting devices placed along or supported from the pipeline. The movement of the main pipeline about the center pivot irrigates a circular portion of a field space, herein referred to as a primary field space. In a square-shaped or an irregularly-shaped field space, irrigation of only a circular portion of the field space leaves corners of the square field space or other irregular perimeter areas without irrigation.
In installations where additional productive capacity of the field space's corners or irregular perimeter areas is desired, these areas can be irrigated by adding at least one auxiliary pipeline adjacent a distal end of the main pipeline, commonly referred to as a corner unit. The auxiliary pipeline irrigates field space areas outside of the circular area, herein referred to as a secondary field space. The auxiliary pipeline is in fluid communication with and supplied by the distal end of the main pipeline. The auxiliary pipeline is capable of moving as needed to extend into the corners or other irregular areas by transitionally rotating about the distal end of the main pipeline as the main pipeline rotates about the center pivot.
In prior art center pivot irrigation machines, the auxiliary pipeline is operable to either lead ahead or lag behind the main pipeline, but not both, when the pipeline is rotating through the field space in a single direction. For a field space that allows for the main pipeline to rotate approximately 360°, the ability for the auxiliary pipeline to either lead or lag the main pipeline is usually not problematic. Regardless of whether the auxiliary pipeline is leading or lagging the main pipeline, the auxiliary pipeline is positioned to allow for uniform application coverage of the secondary field space because the main pipeline rotates a full 360° in the field space. However, in field spaces that are either partially circular, i.e., that do not allow for an approximately 360° rotation of the main pipeline in the field space, or that include boundaries or obstructions that do not optimally allow for the auxiliary pipeline to either lead or lag, but not both, the choice of either a leading or a lagging auxiliary pipeline is insufficient. As used herein, a partially circular field space is defined as any field space that does not allow for an approximately 360° rotation of the main pipeline in the field space. Therefore, partially circular field spaces include, for example, field spaces that allow the main pipeline to rotate approximately 90°, 180°, 270°, or even approximately 350°. It is to be expressly understood that embodiments of the present invention can be used for completely circular field spaces, and that such use would be advantageous in those instances where the field space includes boundaries or obstructions that would be optimally accounted for using the present invention.
More particularly, prior art auxiliary pipelines are programmed to either lead ahead or lag behind the main pipeline during progressive rotation of the main pipeline in a single direction through the field space. The angle of rotation of the auxiliary pipeline with respect to the main pipeline, known as the swing angle, is approximately 80°-170°. In partially circular field spaces, unlike in completely circular field spaces, the main pipeline commonly must reverse direction (i.e., begin moving counterclockwise if initially moving clockwise) because it cannot rotate a full 360° to a beginning position. If the auxiliary pipeline is operable to only lead or lag the main pipeline during progressive rotation of the main pipeline in a single direction, there will necessarily be a portion of the primary field space that remains unirrigated due to the auxiliary pipeline impinging on a boundary or obstruction of the field space.
FIG. 1 illustrates the above-described prior art problem in more detail, wherein an auxiliary pipeline 114 is operable to only either lead or lag a main pipeline 112 during progressive rotation of the main pipeline 112 in a single direction through a field space 138. FIG. 1 presents a field space that is generally rectangular and having north, south, east, and west boundary lines 90,92,94,96, respectively. The irrigation machine 110 has its center pivot positioned generally south-center in the field space 138. When the direction of rotation of the main pipeline 112 is clockwise, the auxiliary pipeline 114 is leading the main pipeline 112; conversely, when the direction of rotation of the main pipeline 112 is counterclockwise, the auxiliary pipeline 114 is lagging the main pipeline 112. Because the auxiliary pipeline 114 is leading the main pipeline 112 when the main pipeline 112 is along a southwest border 98 of the field space 138, the auxiliary pipeline 114 does not obstruct the main pipeline's ability to uniformly irrigate, as denoted at position A on FIG. 1. As the main pipeline 112 begins its clockwise rotation through a primary field space 140, the auxiliary pipeline 114 increases the swing angle from 90° at a general southwest corner 100 of the field space 138, to a swing angle of approximately 155° at a general west corner 102 of the field space, denoted as position B on FIG. 1. As the main pipeline 112 continues its rotation from the west corner 102 to a east corner 104, the auxiliary pipeline 114 tucks back in towards the main pipeline 112 so as to not impinge on the border 90 of the field space 138, which consequently decreases the swing angle of the auxiliary pipeline 114. Eventually, the main pipeline 112 rotates proximate a southeast corner 106 of the field space 138. However, because the auxiliary pipeline 114 is operable only to lead the main pipeline 112, the auxiliary pipeline 114 reaches a southeast border 108 of the field space 138 before the main pipeline 112 and does not allow the main pipeline 112 to rotate generally parallel to the south border 92, as denoted at position C on FIG. 1. Depending on the minimum swing angle between the main and auxiliary pipelines 112,114, at least a portion of the field space 138 is left unirrigated, which wastes available land.
The present invention solves the above-described problems and provides a distinct advance in the art of center pivot irrigation machines. More particularly, embodiments of the present invention provide an auxiliary pipeline operable to both lead and lag a main pipeline of a center pivot irrigation machine during progressive rotation of the main pipeline in a single direction through a field space. To accomplish both the leading and lagging with respect to the main pipeline, the auxiliary pipeline is operable to rotate at least approximately 0° and up to 360° with respect to the main pipeline. The only restriction on the minimum and maximum swing angles and within a 0°-360° rotation is a size of trusses mounted on the main and auxiliary pipelines and the prevention of the respective trusses colliding with each other.
The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention.