Tract-tailored control means and method for center-pivot irrigation apparatus

Sprinkler irrigation apparatus of the general type comprising a center-pivot site for the land tract to be irrigated, a generally horizontal water distributing conduit having sprinklers and also underlying traction supports therealong. The outermost underlying support through hydraulic or electric drive means has substantially constant-speed, but driven intermittently for an average-speed as determined by an arbitrarily settable percentage-on timer means. A primary-timer and a secondary-timer (and perhaps a tertiary-timer, etc.), each being arbitrarily set for different percentage-on values, alternatively exclusively control the outermost support drive means according to tract-tailored automatic switching means dictated by peculiarities of the particular land tract to be irrigated from a single center-pivot apparatus.

Center-pivot sprinkler irrigation apparatuses are described in numerous 
prior patents including inter alia U.S. Pat. Nos. 3,386,661 and 3,608,826. 
Typically, such center-pivots generally include a central-pillar means 
securely non-rotatably anchored at a central site of the land tract to be 
irrigated and extending upwardly along a vertical-axis which is the 
apparatus center-pivot and having thereat an incoming water supply pipe. 
There is a generally horizontal lengthy water distributing conduit 
pivotably attached at its inward-end to the central water supply pipe 
whereby said lengthy conduit is movable about the center-pivot and the 
non-rotatable central-pillar. There is a plurality of underlying traction 
supports disposed at spaced positions along the water distributing conduit 
and including an outermost support provided with electric-drive for 
causing it to travel arcuately overland about the center-pivot. 
As is also taught by the prior art, the electrical power-path flows from a 
power-source to the central-pillar site near which there are display-panel 
and commutator, and thence along the very lengthy water distributing 
conduit to the electric-drive means for the outermost support. The 
electric-drive is conventionally a constant speed motor (which is usually 
dual-directional) which causes the outermost support to travel arcuately 
overland at substantially constant-speed. However, with prevalent 
irrigation practice, the outermost support electric-drive is made to run 
intermittently at regular intervals, as governed by a timer of the 
arbitrarily settable percentage-on type and located at the display-panel 
and through which timer the electrical power-path flows. Thus, the 
outermost support has an average-speed overland determined by the 
arbitrarily selected percentage-on value for the timer. For example, if 
the percentage-on value for the timer is arbitrarily set at 60%, then the 
electric-drive will run 60% of the time and the average-speed is about 60% 
of the constant-speed. 
However, complete reliance upon the single timer control utilized in the 
prior art is inadequate for many land tract conditions wherein the entire 
land tract is serviced by a solitary center-pivot apparatus. For example, 
if two or more intra-tract sectors are planted with different crops having 
different water requirements per unit land-area, then the average-speed 
for each land sector should be varied by the apparatus operator. Another 
example is where a single crop is planted but where a valley-like sector 
is of such proximity to the water table that lower water application per 
unit land-area will suffice. Yet another example is where the apparatus 
oscillates both clockwise and counterclockwise for less than 360.degree. 
about the center-pivot, as is dictated by a situation where an impassable 
gully or farmstead occupies a barrier-sector of the land tract. In the 
barrier-sector example, the freshly-irrigated sectors immediately 
neighboring the barrier-sector have significantly lower water application 
requirements per unit land-area than does the remainder of the land tract. 
Heretofore, the use of a single timer could meet such varying water 
applications per unit land-area for different sectors only by having the 
operator repeatedly re-set the timer percentage-on value. However, this is 
an exceedingly laborious procedure necessitating the operator to expend 
his valuable time and to repeatedly interrupt his personal schedule 
whereby he has become practically enslaved by the apparatus control 
system. 
The general object of the present invention is to provide a tract-tailored 
control means for electric-drive and hydraulic-drive center-pivot 
irrigation apparatuses wherein water applied per unit land-area from a 
solitary center-pivot apparatus can be controlled from sector to sector 
according to the peculiarities of the land tract to be irrigated. 
With the above and other objects and advantages in view, which will become 
more apparent as this description proceeds, the tract-tailored control 
means generally comprises a primary-timer, and a secondary-timer, and 
perhaps too a tertiary-timer, etc., on the display-panel and arranged in 
parallel branches along the electrical power-path, and together with 
patterned template or other tract-tailored automatic switching means 
program for causing the electric current to flow alternatively and 
exclusively through the appropriate timer and according to the 
pre-programmed exigiencies of the particular land tract to be irrigated 
with a solitary center-pivot irrigation apparatus.

Referring initially to FIG. 1, there is shown schematically a land tract 
"E" having a rectangular perimeter 99 and a geographic center 98 at which 
there is a non-rotatably anchored central-pillar assembly 90. The 
sprinkler irrigation apparatus 200 extends radially outwardly from a 
vertical-axis center-pivot (herein synonymous with 98) along a generally 
horizontal water distributing conduit 210 having a plurality of sprinkler 
nozzles and also underlying traction supports (S1, S2, . . . S(N-1), SN) 
spaced therealong. Thus, as the water distributing conduit 210 travels 
overland "E" about its central-pivot (98) inward-end 211, its far-end 219 
arcuately circumscribes an irrigatable field which has a generally 
circular perimeter 100. As had been alluded to in the introductory portion 
of this application, certain sectorial areas of the land tract to be 
irrigated might have different water application requirements per unit 
land-area. A typical, though non-limiting example, might be as seen in 
FIG. 1. The entire tract bounded by 100 is planted with Crop #1, except 
for two sectors: a very small unplanted barrier-sector 102 at fence-line 
obstruction 101; and a 90.degree. sector 105 which is planted with Crop #2 
having lower watering requirements than does Crop #1. Sector 107 
represents a valley-like depression sector having relatively lower water 
application requirements per unit land-area, perhaps because of relative 
proximity to the underground water table. Thus, assuming that irrigation 
apparatus 200 is of the dual-directional electric-drive means "DM" type 
and is programmed to reverse its overland travel direction upon attaining 
the barrier-sector 102 from sectors 103 or 109, these freshly irrigated 
sectors 103 and 109 have lower water requirements per unit land-area for 
each pass whereby apparatus 200 should have a higher average-speed in 
sectors 103 and 109 (relative to sectors 104 and 108). 
Thus, a typical drive means ("DM") cycle for conduit 210 overland tract 100 
might be as follows: faster at secctor 103, slower at sector 104, faster 
at sector 105, slower at sector 106, faster at sector 107, slower at 
sector 108, faster at sector 109, reversal, faster at sector 109, slower 
at sector 108, etc. To attain this objective, there is primary-timer "PT", 
secondary-timer "ST", and tract-tailored automatic switching means 
affecting through timers "PT" and "ST" the average-speed for the apparatus 
at outermost support "SN" having electric-drive "DM". For purposes of 
operational consistency, primary-timer "PT" might be reserved for lower 
percentage-on values and secondary-timer "ST" for higher percentage-on 
values, and this convention will be adhered to for the purposes of clarity 
herein. Herein, as exemplified in FIG. 2, there is a template-form 
tract-plan 80 having a circular central opening 81 and peripheral lobes 
and intervening recesses corresponding in angular position and extent to 
the significant sectorial peculiarities of land tract "E" of FIG. 1. For 
example, recesses 84, 86, and 88 correspond in angular position and extent 
for land sectors 104, 106, and 108, respectively, which have relatively 
high water requirements per unit land-area, and for which actuation of one 
of the timers e.g. "PT"(but not the other parallel timers e.g. "ST") is 
necessary. Template lobes 83, 85, and 87 correspond in angular position 
and extent to land sectors 103, 105, and 107, respectively, which have 
relatively low water requirements per unit land-area, and for which the 
secondary-timer "ST"(but not the primary timer "PT") is necessary. 
The tract-plan program (e.g. 80, 180, 280, etc.) portion of the 
tract-tailored automatic switching means for the parallel duty cycle 
timers ("PT", "ST", etc.) surrounds the center-pivot vertical-axis 98. 
Tract-plan embodiment 80 non-rotatably surrounds vertical-axis 98, herein 
stationarily securely surrounding the upright central water supply pipe 95 
which non-rotatably surrounds vertical-axis 98. Water supply pipe 95 
provides a portion of the non-rotatable central-pillar assembly 90 which 
typically comprises a concrete footing 91 anchored into the earthen tract 
"E" at 98, four diagonal braces 92 converging upwardly and inwardly from 
footing 91 to connect with a collar 93 for pipe 95. Herein are also four 
horizontal braces 94 for steadying diagonal braces 92 and to which braces 
94 the display-panel 96 might be attached. Commutator 97 might also be 
considered as a part of central-pillar assembly 90. It is to display-panel 
96 that the duty cycle timers (e.g. "PT", "ST", etc.) are attached. 
In addition to the tract-plan program, the tract-tailored automatic 
switching means comprises an electrical selector-switch which slavishly 
follows the sectorial indicators of the tract-plan, there being relative 
angular movement between the tract-plan and the selector-switch e.g. 70, 
as the water distributing conduit 210 and the outermost support "SN" move 
around center-pivot 98. The selector-switch 70 might be of the 
two-positions "on-off" type such as comprising a spring-loaded pushbutton 
75 wherein at its resiliently outwardly extended condition to the 
selector-switch directs electrical current to flow therefrom to 
primary-timer "PT" (but not to "ST"). However, when the pushbutton 75 is 
depressed to the "on" condition 72, as by the prominent sectorial 
indicators of the tract-plan (80, 180, etc.), electrical current flows to 
secondary-timer "ST"(but not to "PT"). For the FIG. 2 embodiment, relative 
angular movement between the tract-plan 80 (which is non-rotatable at 
stationary pipe 95) and the selector-switch 70 is provided by mounting the 
selector-switch on the water distributing conduit 210. For example, a 
bracket 77 depending from conduit section 212 might carry selector-switch 
70 at co-elevational relation with tract-plan 80. The pushbutton 75 is 
perpendicular to vertical-axis 98 and is in continuous contact with the 
lobed and recessed periphery of tract-plan 80. 
Turning now to the electrical circuitry diagram of FIG. 6. There are shown 
two duty cycle timers "PT" (primary) and "ST"(secondary) attached to the 
display-panel 96. The two timers "PT" and "ST" are structurally identical 
and being of the arbitrarily settable percentage-on type as are well known 
in the prior art including inter alia: U.S. Pat. No. 3,160,719, etc. Each 
timer identically comprises four external terminals appropriately 
connected to internal synchronous motor "M" and cam-operated switch "C". 
An optional bypass-switch "BP" might be attached to display-panel 96, for 
purposes to be explained later; the electrical wiring for bypass-switch 
"BP" is shown in broken lines in FIG. 6. 
Still referring to FIG. 6, and assuming in FIGS. 1, 2, 4, and 6 (as 
indicated by double-headed curved arrow) that the conduit 210 and the 
outermost support "SN" of apparatus 200 are moving clockwise across land 
sector 105. Thus, the pushbutton 75 of selector-switch 70 (which is 
co-movable with conduit 210) is depressed by the tract-plan lobe 85 and 
selector switch 70 is in the "on" condition 72. Accordingly, the 
electrical power-path is as follows and as indicated in double-arrowheads 
in FIG. 6; from power-source "PS"; to selector-switch terminal 72; to 
terminals 21, 22, and then 23 of secondary-timer "ST"; to commutator 97; 
to drive means "DM" of outermost support "SN"; and back to "PS". Assuming 
that the secondary-timer "ST" is reserved for higher percentage-on 
settings than is the primary-timer "PT", this results in conduit 210 
passing relatively quickly through land sector 105. However, when conduit 
210 enters land sector 106, selector-switch pushbutton 75 is allowed to 
outwardly extend at tract-plan recess 86 whereupon the selector-switch 70 
is in the "off" condition 73. Accordingly, the electrical power-path, as 
indicated in single-arrowheads in FIG. 6, proceeds: from power-source 
"PS"; to selector-switch terminal 73; to terminals 11, 12, and then 13 of 
primary-timer "PT"; to commutator 97; to drive means "DM" of outermost 
support "SN"; and back to "PS". This results in conduit 210 passing 
appropriately relatively slower through land sector 106 as compared to 
land sector 105. Next, as conduit 210 enters land sector 107, 
secondary-timer "ST" again controls the drive means "DM", etc. 
FIG. 5 alludes to another method of providing relative angular movement 
between the tract-plan 80 and the selector-switch 70. Tract-plan 80 
securely surrounds elbow 211 and is co-rotational therewith about 
central-pivot 98. Selector-switch 70 is stationarily attached to the 
central-pillar 90 as with mounting bracket 79 whereby selector-switch 70 
is non-rotatable about center-pivot 98. 
FIG. 7 alludes to an alternate tract-plan embodiment 180 for land tract "E" 
of FIG. 1. Tract-plan embodiment 180 comprises a circular base-plate 180A 
having a central-opening 181 at center-pivot 98. Base-plate 180A is 
securely attachable to the commutator housing 97A and hence non-rotatable 
about center-pivot 98. Equidistant from central-opening 181 are 
projections (183, 185, 187, and 189) upstanding from base-plate 180A and 
corresponding in angular position and extent for land sectors 103, 105, 
107, and 109, respectively. Selector-switch 70 is co-movable with conduit 
210 and its upright push-button 75 (parallel to vertical-axis 98) 
slavishly follows the projections 183, 185, 187, and 189, and the 
intervening unobstructed base-plate 180A. Thus, the tract-plan 180 
together with the selector-switch 70 provide a tract-tailored automatic 
switching means between timers "PT" and "ST", analagous to that already 
described. 
Bypass-switch "BP" of FIG. 6 might be a double-throw switch having a 
manually-operated toggle "T" which can result in the electrical power-path 
being permanently shunted via terminal 33 to the primary-timer "PT"(and to 
the indefinite exclusion of secondary-timer "ST"). This optional procedure 
might be used, inter alia: when the water application rates per unit-area 
should be made substantially constant throughout entire land tract "E", 
for rapidly repositioning apparatus 200, etc. However, manipulation of 
toggle "T" will once again allow the electric power-path to flow via 
terminal 31 to secondary-timer "ST" during appropriate land sectors as 
dictated by the tract-plan e.g. 80, 180. 
The tract-tailored control means apparatus and method of the present 
invention entail the tailor-making step of a predetermined tract-plan 
program (e.g. 80, 180) having prominent indicators (e.g. 85, 185, etc.) 
corresponding to sector-to-sector irrigation requirements. This is 
necessarily an empirical procedure requiring a sector-to-sector water 
requirements appraisal for the particular land tract to be irrigated. Thus 
far it has been illustrated that two different average-speeds for 
apparatus 200 (and hence two different water application rates per unit 
land-area) will meet all the sectorial peculiarities for the land tract 
"E". On this basis, two parallel timers ("PT" and "ST") would suffice. 
Conceiveably, however, sector-to-sector land appraisal might conclude that 
three, or even more, vastly different water application rates might be 
appropriate for servicing by a solitary apparatus 200. In such situations, 
additional duty cycle timers e.g. tertiary-timer, etc., would need to be 
placed in parallel with the respective parallel timers "PT" and "ST". 
Tract-plan and selector-switch appropriate to tertiary and higher ordinal 
parallel timers might take analagous form. Relative to the addition of a 
tertiary-timer, there could be two separate tract-plans analagous to 80 
and each having its own selector-switch 70, the first tract-plan having 
lobes actuating the secondary-timer and the second tract-plan having lobes 
for actuating the tertiary-timer. 
From the foregoing, the construction, operation, and method steps for the 
tract-tailored control means will be readily understood and further 
explanation is believed to be unnecessary. However, since numerous 
modifications and changes will readily occur to those skilled in the art, 
it is not desired to limit the invention to the exact construction shown 
and described, and accordingly, all suitable modifications and equivalents 
may be resorted to, falling within the scope of the appended claims.