U.S. patent application number 14/308774 was filed with the patent office on 2017-11-09 for electrically actuated variable pressure control system.
This patent application is currently assigned to Capstan Ag Systems, Inc. The applicant listed for this patent is JEFFREY JOHN GRIMM, GRAEME W. HENDERSON. Invention is credited to JEFFREY JOHN GRIMM, GRAEME W. HENDERSON.
Application Number | 20170320085 14/308774 |
Document ID | / |
Family ID | 37545678 |
Filed Date | 2017-11-09 |
United States Patent
Application |
20170320085 |
Kind Code |
A9 |
GRIMM; JEFFREY JOHN ; et
al. |
November 9, 2017 |
ELECTRICALLY ACTUATED VARIABLE PRESSURE CONTROL SYSTEM
Abstract
An electrically-actuated variable pressure control system for
use with flow-controlled liquid application systems. Direct acting
solenoid valves are pulsed at varying frequencies and duty
cycles0000change the resistance to flow encountered by the
flow-controlled liquid application system. This pulsing solenoid
valve technique preserves a high degree of accuracy and uniformity
through a wide range of pressure control. This wide range of
pressure control indirectly allows the flow-controlled liquid
application system to operate over a wider range of flow control,
yielding indirect benefits to performance and productivity. When
the solenoid valves are attached to pressure-atomization spray
nozzles, control over spray pattern and droplet size is further
achieved.
Inventors: |
GRIMM; JEFFREY JOHN;
(Holton, KS) ; HENDERSON; GRAEME W.;
(Jacksonville, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GRIMM; JEFFREY JOHN
HENDERSON; GRAEME W. |
Holton
Jacksonville |
KS
FL |
US
US |
|
|
Assignee: |
Capstan Ag Systems, Inc
Topeka
KS
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20140299673 A1 |
October 9, 2014 |
|
|
Family ID: |
37545678 |
Appl. No.: |
14/308774 |
Filed: |
June 19, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11438183 |
May 22, 2006 |
|
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14308774 |
|
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60688259 |
Jun 7, 2005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B05B 9/0413 20130101;
F16K 31/0655 20130101; A01G 25/16 20130101; B05B 1/08 20130101;
B05B 9/06 20130101; B05B 9/0423 20130101; B05B 12/085 20130101 |
International
Class: |
B05B 12/08 20060101
B05B012/08; B05B 9/06 20060101 B05B009/06; B05B 9/04 20060101
B05B009/04; F16K 31/06 20060101 F16K031/06; A01G 25/16 20060101
A01G025/16 |
Claims
1-19. (canceled)
20. A method of controlling pressure and flow for application of an
agrochemical from an agricultural spraying system, the method
comprising: pumping an agrochemical from a tank through a pipe to
an actuating valve including a nozzle and an actuator assembly, the
nozzle having an orifice defined therethrough, the actuator
assembly being configured to control an emission of the
agrochemical from the orifice; regulating a predetermined flow rate
of the agrochemical through the pipe by a regulating valve
connected to the pipe; controlling the predetermined flow rate with
a flow controller in communication with the regulating valve;
sensing a pressure in the pipe using a pressure sensor connected to
the pipe; and changing a flow resistance with a pressure controller
based on the sensed pressure to maintain a predetermined pressure
in the pipe, the pressure controller in communication with the
pressure sensor, the pressure controller being configured to for
the emission of the agrochemical from the orifice, the
predetermined pressure dictated by the flow resistance.
21. The method as in claim 20, further comprising changing the flow
rate to change the pressure.
22. The method as in claim 20, further comprising assessing
correctness of the flow rate with the flow controller.
23. The method as in claim 20, further comprising opening the
regulating valve when the flow rate is too low.
24. The method as in claim 20, further comprising closing the
regulating valve when the flow rate is too high.
25. The method as in claim 20, further comprising assessing
correctness of the sensed pressure with the pressure sensor.
26. The method as in claim 20, further comprising increasing flow
resistance when the sensed pressure is too low.
27. The method as in claim 26, wherein decreasing a duty cycle of a
square wave increases flow resistance.
28. The method as in claim 20, further comprising decreasing flow
resistance when the sensed pressure is too high.
29. The method as in claim 26, wherein increasing a duty cycle of a
square wave decreases flow resistance.
30. A method for regulating pressure for application of an
agrochemical from an agricultural spraying system, the method
comprising: directing the agrochemical through a pipe of the
agricultural spraying system to an actuating valve including a
nozzle and an actuator assembly, the nozzle having an orifice
defined therethrough, the actuator assembly being configured to
control an emission of the agrochemical from the orifice; sensing a
pressure in the pipe using a pressure sensor connected to the pipe;
and adjusting a flow resistance associated with the agrochemical
based on the sensed pressure to maintain a predetermined pressure
in the pipe for emission of the agrochemical from the orifice,
wherein the flow resistance is adjusted by continuously pulsing the
actuator assembly according to a duty cycle.
31. The method of claim 30, wherein adjusting a flow resistance
associated with the agrochemical based on the sensed pressure
comprises transmitting control signals from a pressure controller
of the agricultural system to the actuator assembly, the control
signals being associated with the duty cycle.
32. The method of claim 31, wherein the control signals are
generated by a square wave generator associated with the pressure
controller.
33. The method of claim 31, wherein the pressure in the pipe is
sensed using a pressure sensor communicatively coupled to the
pressure controller.
34. The method of claim 30, wherein adjusting a flow resistance
associated with the agrochemical based on the sensed pressure
comprises increasing the duty cycle at which the actuator assembly
is pulsed in order to decrease the flow resistance when the sensed
pressure exceeds the predetermined pressure.
35. The method of claim 30, wherein adjusting a flow resistance
associated with the agrochemical based on the sensed pressure
comprises decreasing the duty cycle at which the actuator assembly
is pulsed in order to increase the flow resistance when the sensed
pressure is less than the predetermined pressure.
36. The method of claim 30, wherein the actuator assembly is
continuously pulsed in order to maintain the predetermined pressure
independent of a predetermined flow rate of the agrochemical
through the pipe.
37. The method of claim 36, further comprising regulating the
predetermined flow rate of the agrochemical through the pipe via a
regulating valve connected to the pipe.
38. The method of claim 30, wherein the actuator assembly is
movable from a closed position to an open position, the actuator
assembly being configured to seal the orifice when the actuator
assembly is moved to the closed position.
39. The method of claim 30, wherein the predetermined pressure is
dictated by the flow resistance.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit of U.S. Provisional Patent
Application Ser. No. 60/688,259, filed Jun. 7, 2005.
BACKGROUND OF THE INVENTION
[0002] Spraying is a well-known method of applying a wide variety
of bulk materials, primarily in liquid or a mixture of liquid and
powder in a fluid propellant medium. Such spray materials can be
dispensed in air currents, under liquid pressure, by gravity flow,
or with any other suitable discharge means.
[0003] Spray application of bulk materials offers many potential
advantages, including efficiency, uniformity of coverage and
flexibility to adapt spraying equipment to various conditions
unique to the objects being sprayed and their particular
environments.
[0004] However, a disadvantage with many spray systems relates to
the drift of spray particles and droplets away from their intended
targets. Such drift is at best inefficient, as in the case of the
overspray which represents wasted spray material, and in more
serious situations can cause damage to nearby property, environment
and people.
[0005] The field of agricultural spraying includes pesticide
application for crop pest management and the application of
fertilizer and growth regulators for nutrient management. The
agricultural spraying industry is quite large, with pesticides
alone currently accounting for approximately $3,000,000,000 in
estimated annual expenditures. However, the use of pesticides in
agricultural applications produces substantial benefits in crop
yields with an estimated annual savings of approximately
$12,000,000,000 in crops which would otherwise be lost to pests.
The spray application of fertilizers and growth regulators likewise
produces substantial benefits in crop yields and the like.
[0006] Notwithstanding the substantial advantages of agricultural
spraying applications of pesticides and other spray materials,
agricultural spraying is generally a relatively inefficient
process. Factors which contribute to such inefficiencies include
the susceptibility of sprayed materials to wind drift, overspray
and inaccurate placement on the intended target crop plants.
Irregularities in terrain and nonuniform plantings also contribute
to the inconsistent and inefficient application of agricultural
spray materials. Moreover, variations in ambient conditions such as
wind, humidity levels and temperature tend to reduce the uniformity
and efficiency with which spray materials are applied to their
intended crop targets.
[0007] In addition to the inefficiencies associated with
misdirected agricultural spray materials, overspray and spray drift
can create significant problems if the materials are inadvertently
applied to adjoining areas for which they were not intended. Such
misapplication of agricultural spray materials can result in crop
damage, injury to livestock, contamination of
environmentally-sensitive areas and unnecessary human exposure to
toxic materials.
[0008] The problems associated with the misapplication of
agricultural spray materials are exacerbated by the use of larger
spraying equipment covering wider swaths, high speed vehicles,
air-blast spraying, and by aerial spraying. The inherent
difficulties associated with large-scale spraying operations are
balanced against the relative efficiencies which are achieved by
covering larger areas more rapidly with wide-swath spraying
equipment.
[0009] The Heiniger et al, U.S. Pat. No. 5,348,226 discloses a
spray boom system with automatic boom end height control which uses
an ultrasonic height control system for conforming the spray boom
orientations to topography and slope of a zone being sprayed in
order to increase uniformity of coverage. Uniform spray nozzle
height can be a significant factor in achieving uniform spray
material coverage.
[0010] Another important factor in spray material deposition
control is the droplet size spectrum of the liquid being sprayed.
Spray droplet size has been shown to significantly affect both the
efficacy of pesticide treatments and the potential for off-target
spray movement. Such off-target movement and deposition of spray is
often called "spray drift". Insecticides, fungicides, growth
regulators and post-emergence herbicides are generally more
effective when applied using relatively small droplets, which tend
to provide greater penetration of plant canopies and uniform
coverage of foliar surfaces. Smaller spray droplets, with shorter
mechanical relaxation times, have the advantage of more closely
following air currents into dense plant canopies for achieving
greater penetration and more uniform coverage. Conversely, such
droplet mobility associated with smaller droplet sizes can
exacerbate problems associated with spray drift away from
application sites. Generally speaking, larger droplets tend to fall
more directly due to their greater mass and are thus less
susceptible to spray drift, evaporation, etc.
[0011] A common technique for controlling the application rate of
spray liquid involves adjusting the spray liquid pressure, for
example, with the use of a throttling valve in a main distribution
line of a spray liquid distribution system. However, altering the
liquid pressure also generally alters the droplet size, thus
effecting the deposition and its susceptibility to spray drift,
evaporation, etc.
[0012] The Giles et al. U.S. Pat. No. 5,134,961 discloses an
electrically actuated variable flow control system wherein solenoid
valves are actuated by square wave pulses, which can be varied in
frequency and duty cycle for controlling volumetric flow through
spray nozzles. The volumetric flow rate can thus be varied without
changing droplet size and spray pattern since the liquid supply
pressure can be maintained constant.
[0013] In addition to the aforementioned advantages of
independently and selectively controlling the application rate and
median droplet size setpoints, substantial advantages can be
achieved by controlling spray deposition with respect to field
position of a spray vehicle, such as a ground vehicle or an
aircraft. Such position-responsive control can be important because
spray zones in and around a field to be sprayed can require
different treatment by a spray system, ranging from little or no
application of spray materials (i.e., outside the boundary of a
given site) to a maximum application rate in heavily infested areas
or regions of poor fertility. The boundaries for such differential
application rate spray zones can be irregular, with such
irregularities increasing the difficulty of manually altering spray
system operating conditions by an on-board operator. Moreover,
problems can arise due to operator reaction times when changed
field conditions call for adjustments to the spray conditions. For
example, if an operator is alerted that he or she has crossed a
field boundary or property line and initiates a procedure for
altering spray application, most spray control systems have an
inherent delay which may cause overspray problems.
[0014] To address some of these problems, control systems and
methodology have heretofore been developed that respond to spray
vehicle positions. For example, Ortlip U.S. Pat. No. 4,630,773
discloses a method and apparatus for spraying fertilizer wherein a
computerized control system includes a field map with digital
information concerning various soil types. The control system
disclosed therein dispenses fertilizer in accordance with the
optimum applications for the different soil conditions encountered
in a target field. The spray liquid application rate is
automatically adjusted for vehicle speed. Sensors are disclosed for
determining malfunctions of the application hardware. However, the
application control provided by the Ortlip apparatus occurs only
along the direction of travel and not along the boom section.
Moreover, the Ortlip apparatus does not provide for droplet size
control, drift control or spray transport modeling for spray liquid
deposition prediction.
[0015] Recent improvements in the accuracy and effectiveness of the
global positioning system (OPS) for civilian applications have also
created opportunities for greater automation of agricultural
spraying by controlling agricultural spraying equipment with
positioning systems responsive to specific field conditions. For
example, Teach U.S. Pat. No. 5,334,987 discloses an agricultural
aircraft control system using the global positioning system. The
Teach agricultural aircraft control system is adapted for
automatically opening a dispenser valve for releasing chemicals in
response to the aircraft flying within the boundaries of an
agricultural field. Moreover, the Teach system provides for
recording flight data. However, the Teach system does not provide
for droplet size control, drift reduction, spray transport modeling
and gradients of application rates to avoid drift in the
combination of the present invention.
[0016] Models for predicting dispersion and deposition of aerially
released material have been in development for approximately the
past 35 years in joint projects between the U.S.D.A. Forest
Service, in cooperation with the U.S. Army. Computerized codes
which are currently available include AGDISP (Agricultural
DISPersal) (Bilanin et al,, 1989) and FSCBG (Forest Service
Cramer-Barry-Graham) (Teske et al., 1992b). Such computerized
models can be useful for predicting dispersion patterns of various
liquids under a variety of ambient conditions, heights, etc.
[0017] Giles et a teach a "Networked Diagnostic and Control System
for Dispensing Apparatus", U.S. patent application Ser. No.
11/135,054, filed May 23, 2005, which is incorporated herein by
reference thereto. Giles et al, discloses monitoring the flow rate
of a fluid through a nozzle and monitoring the flow pattern that is
emitted from the nozzle. A further need exists in the industry for
a system that is also capable of maintaining a desired pressure in
the system.
BRIEF SUMMARY OF THE INVENTION
[0018] In general, the present invention is directed to a system
and method of controlling pressure and flow for application of an
agrochemical from an agricultural spraying system. The invention is
suitable for use with any of various types of spraying systems and
in various and many application systems. For example, the system of
the present invention can be used in conjunction with agricultural
spray systems that are designed to apply liquids to a field.
[0019] The component parts of the system are simple and economical
to manufacture, assemble and use. Other advantages of the invention
will be apparent from the following description and the attached
drawings, or can be learned through practice of the invention.
[0020] In one embodiment of the present invention, an agricultural
spraying system includes a valve having a nozzle and an actuator
assembly, the nozzle having an orifice defined therethrough, the
actuator assembly being configured to control an emission of an
agrochemical from the orifice; a pipe connected to the valve and
configured to deliver the agrochemical thereto; a pressure sensor
connected to the pipe for sensing a pressure in the pipe; and a
pressure controller in communication with the pressure sensor, the
pressure controller being configured to change a flow resistance
based on the sensed pressure to maintain a predetermined pressure
in the pipe for the emission of the agrochemical from the
orifice.
[0021] In this aspect of the invention, the nozzle is a
pressure-atomization spray nozzle is configured to produce a
desired droplet size spectra and an agrochemical spray pattern.
[0022] Also in this aspect of the invention, the actuator assembly
includes a reciprocating solenoid actuator configured to move
relative to the orifice when a voltage is applied to the
reciprocating solenoid actuator.
[0023] Further in this aspect of the invention, the actuator
assembly includes a coil, a guide, and a plunger, the coil being
disposed about the guide, the plunger being interposed between the
guide and the orifice and being configured to move relative to the
orifice when a voltage is applied to the coil.
[0024] In this aspect of the invention, the agricultural spraying
system further includes means for controlling the actuator
assembly, the actuator assembly defining an open position and a
closed position. The means for controlling can be a square wave
generator being configured to apply a voltage to the actuator
assembly to move the actuator assembly from the closed position to
the open position for the emission of the agrochemical from the
orifice.
[0025] Also in this aspect of the invention, the square wave
generator is configured to modulate a square wave frequency and a
duty cycle to change the flow resistance for the emission of the
agrochemical from the orifice. The square wave generator can be
located in or in communication with the pressure controller.
[0026] Further in this aspect of the invention, the agricultural
spraying system includes an agrochemical tank for holding the
agrochemical, the agrochemical tank connected to the pipe.
[0027] In this aspect of the invention, the agricultural spraying
system can also have a pump for pumping the agrochemical through
the pipe. The pump can be a positive displacement pump or a
centrifugal pump.
[0028] Also in this aspect of the invention, the agricultural
spraying system can have a wheel and a piston, the piston connected
to the wheel and to the positive displacement pump, the piston
being configured to reciprocate the positive displacement pump as
the wheel turns.
[0029] Further in this aspect of the invention, the agricultural
spraying system includes a plurality of valves, each of the valves
being configured for independent operation, or at least two of the
valves being configured as a group to stop the emission of the
agrochemical from the group.
[0030] In another embodiment of the present invention, an
agricultural spraying system includes an actuating valve including
a nozzle and an actuator assembly, the nozzle having an orifice
defined therethrough, the actuator assembly being configured to
control an emission of an agrochemical from the orifice; a pipe
connected to the actuating valve and configured to deliver the
agrochemical thereto; a regulating valve connected to the pipe for
regulating a predetermined flow rate of the agrochemical through
the pipe; a flow controller in communication with the regulating
valve to control the predetermined flow rate; a pressure sensor
connected to the pipe for sensing a pressure in the pipe and a
pressure controller in communication with the pressure sensor, the
pressure controller being configured to change a flow resistance
based on the sensed pressure to maintain a predetermined pressure
in the pipe for the emission of the agrochemical from the orifice,
the predetermined pressure dictated by the flow resistance.
[0031] In this aspect of the invention, the agricultural spraying
system further includes a square wave generator being configured to
apply a voltage to the actuator assembly to move the actuator
assembly from a closed position to an open position for the
emission of the agrochemical from the orifice. More particularly,
the square wave generator can modulate a square wave frequency and
a duty cycle to change the flow resistance for the emission of the
agrochemical from the orifice.
[0032] Also in this aspect of the invention, the pressure
controller determines the predetermined flow resistance based on a
system speed, a system condition, an application rate, a target
area size, a geographic location, a field position, a weather
phenomenon and combinations thereof.
[0033] Further in this aspect of the invention, the pressure
controller determines the predetermined pressure and maintains the
predetermined pressure based on a system speed, a system condition,
an application rate, a target area size, a geographic location, a
field position, a weather phenomenon and combinations thereof.
[0034] In this aspect of the invention, the agricultural spraying
system also includes a controller configured to set the
predetermined resistance to flow.
[0035] In yet another embodiment of the present invention, a method
of controlling pressure and flow for application of an agrochemical
from an agricultural spraying system is provided. The method
includes pumping an agrochemical from a tank through a pipe to an
actuating valve including a nozzle and an actuator assembly, the
nozzle having an orifice defined therethrough, the actuator
assembly being configured to control an emission of the
agrochemical from the orifice; regulating a predetermined flow rate
of the agrochemical through the pipe by a regulating valve
connected to the pipe; controlling the predetermined flow rate with
a flow controller in communication with the regulating valve;
sensing a pressure in the pipe using a pressure sensor connected to
the pipe; and changing a flow resistance with a pressure controller
based on the sensed pressure to maintain a predetermined pressure
in the pipe, the pressure controller in communication with the
pressure sensor, the pressure controller being configured to for
the emission of the agrochemical from the orifice, the
predetermined pressure dictated by the flow resistance.
[0036] In this aspect of the invention, the method further includes
changing the flow rate to change the pressure.
[0037] Also in this aspect of the invention, the method further
includes assessing correctness of the flow rate with the flow
controller.
[0038] Further in this aspect of the invention, the method includes
opening the regulating valve when the flow rate is too low.
[0039] Also in this aspect of the invention, the method further
includes closing the regulating valve when the flow rate is too
high.
[0040] In this aspect of the invention, the method further includes
assessing correctness of the sensed pressure with the pressure
sensor.
[0041] Also in this aspect of the invention, the method further
includes increasing flow resistance when the sensed pressure is too
low.
[0042] In this aspect of the invention, decreasing a duty cycle of
a square wave increases flow resistance.
[0043] Further in this aspect of the invention, the method includes
decreasing flow resistance when the sensed pressure is too
high.
[0044] In this aspect of the invention, increasing a duty cycle of
a square wave decreases flow resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] Further aspects and advantages of the invention will be
apparent from the following description, or can be learned through
practice of the invention, in combination with the drawings, which
serve to explain the principles of the invention but by no means
are intended to be exhaustive of all of possible manifestations of
the invention. Thus, at least one embodiment of the invention is
shown in the drawings in which:
[0046] FIG. 1 is a perspective view of a dispensing system
according to an aspect of the present invention installed in an
environment for which it is intended to be used;
[0047] FIG. 2 is a schematic of a flow control system that can be
employed in the system of FIG. 1, particularly showing a
ground-speed-compensating, positive-displacement pump and an
electrically-actuated variable pressure control system according to
one aspect of the invention;
[0048] FIG. 3A shows a sectional view of a solenoid valve in an
open position;
[0049] FIG. 3B shows a sectional view of the solenoid valve as in
FIG. 3A in a closed position;
[0050] FIG. 4 shows a puke width modulation technique for various
duty cycles employed in the electrically-actuated pressure control
system as in FIG. 1;
[0051] FIG. 5 is a schematic of another flow control system that
can be employed in the system of FIG. 1, particularly showing a
flow meter, a flow regulating valve and an electrically-actuated
variable pressure control system;
[0052] FIG. 6 is a graph showing an interdependent relationship
between flow control and pressure control when an
electrically-actuated variable pressure control system is used in
conjunction with a flow control system according to an aspect of
the invention;
[0053] FIG. 7 shows a flow chart of control logic employed by the
flow control system and the pressure control system as in FIG. 6;
and
[0054] FIG. 8 is an elevational view of a control panel used to
control the foregoing embodiments according to a further aspect of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0055] Detailed reference will now be made to the drawings in which
examples embodying the present invention are shown. The detailed
description uses numerical and letter designations to refer to
features of the drawings. Like or similar designations of the
drawings and description have been used to refer like or similar
parts of the invention.
[0056] The drawings and detailed description provide a full and
written description of the invention, and of the manner and process
of making and using it, so as to enable one skilled in the
pertinent art to make and use it, as well as the best mode of
carrying out the invention. However, the examples set forth in the
drawings and detailed description are provided by way of
explanation only and are not meant as limitations of the invention.
The present invention thus includes any modifications and
variations of the following examples as come within the scope of
the appended claims and their equivalents.
[0057] As broadly embodied in FIGS. 1 and 2, an exemplary
agricultural system, designated in general by the numeral 10,
broadly includes a tractor 12 having an electrically-actuated
variable pressure control system 14. As shown, the tractor 12
includes a cab 16, a plurality of wheels 18A at least one boom
wheel 18B for engaging a section of ground with a crop, produce,
product or the like (generally, P), a tank or reservoir 22, and a
spray boom 24 with a plurality of nozzles 34 attached to the spray
boom 24. The tank 22 holds a liquid, a mixture of liquid and
powder, or other product designated in general by the letter S. The
liquid can be a quantity of water or an agrochemical such as a
fertilizer or a pesticide. Likewise, the liquid-powder mixture can
be the agrochemical. Thus, the product S can be sprayed from the
nozzles 34 onto a crop or product or the ground. P itself as shown
in FIG. 1 and described in greater detail by example operation
below.
[0058] FIG. 2 more particularly shows the boom wheel 18B attached
to a slider-crank or piston mechanism 26, which is connected to a
ground speed compensating positive displacement pump 28. As shown,
the boom wheel 18B rolls across the ground P and turns a
slider-crank mechanism 26, which reciprocates the positive
displacement pump 28. The positive displacement pump 28 is
calibrated to apply a specific amount per acre of product S to soil
of the ground P.
[0059] As briefly introduced, the product S is contained in the
tank 22 and enters the positive displacement pump 28 through a
suction pipe 30. The product S flows from the positive displacement
pump 28, through a boom pipe 32, to the direct acting solenoid
valve equipped nozzles 34. As shown in FIGS. 1 and 2, the product S
flows from the nozzles 34 and is applied to the ground P in various
ways; e.g., pulsed, patterned and the like as taught by Giles et
al, in U.S. Pat. No. 5,134,961 and incorporated herein by reference
thereto. The skilled artisan will appreciate that pipe as used
herein can mean any type of conduit or tube made of any suitable
material such as metal or plastic. The skilled artisan will further
appreciate that other ground application devices can be added to
provide varying effects of placement of the product S on top or
below a soil surface of the ground P, such as via pipes, knives,
coulters, and the like.
[0060] FIG. 2 further shows a pressure sensor 52, which measures
the pressure in the boom pipe 32. The pressure sensor 52 sends this
pressure information to a pressure controller 54. In this example,
the pressure controller 54 pulses the direct acting solenoid valve
equipped nozzles 34 with a frequency and duty cycle that maintains
a specific pressure within the boom pipe 32. An example of this
operation is described below.
[0061] Turning now to FIGS. 3A and 3B, the direct acting solenoid
valve equipped nozzle 34 is shown respectively in open and closed
positions. The direct acting solenoid nozzle 34 pulses with a
frequency and duty cycle such that an orifice 40 is active only
when the valve-equipped nozzle 34 is open. The frequency is
sufficiently fast to diminish any effects of pulsing on the total
system, therefore creating a controlled variable resistance to
flow.
[0062] More specifically, as shown in FIGS. 3A and 3B, the nozzle
34 has a body 36 including mounting means such as a bracket or
screw-fitting 38 for mounting the nozzle 34 to the boom pipe 32. As
shown, the orifice 40 is configured for outlet flow F1 and inlet
flow F2. This aspect of the invention is described in greater
detail below.
[0063] As particularly shown in FIG. 3B, the nozzle 34 also
includes an actuator assembly 41, which has an actuator or coil 42
located on or around a guide 44. As shown, a plunger 46 is movably
positioned between the guide 44 and the orifice 40. A square wave
generator 55 is connected to the nozzle 34 and applies an electric
signal or voltage 56 to the coil 42, which establishes a magnetic
field. The magnetic field causes the guide 44 to become magnetized,
which attracts the plunger 46. In this example, the magnetic force
of the guide 44 overcomes a spring force of a spring 48 and a force
of the inlet flow F2 as applied to the orifice 40. When the plunger
46 lifts a seal 50 from the orifice 40, the outlet flow F1
results.
[0064] FIG. 4 shows a pulse width modulation (PWM) signal used to
actuate the direct acting solenoid nozzle 34 as in FIGS. 1 and 2.
In this example, the electric signal 56 is pulsed with a fixed
period length 58 of 0.1 seconds. When the signal 56 is high; i.e.,
when voltage is present, the pulse is shown at the ON position. As
shown, the signal 56 remains high or ON for a portion of the period
length 58 before switching low; i.e., no voltage is present. The
relation of on-time to period length 58 is called a duty cycle 60
and is measured in percent (%). Three duty cycles of 30%, 50% and
90% are shown in FIG. 4. As described with respect to FIG. 3 above,
the directing acting solenoid nozzle 34 will open and close with
this on/off pulse. For example, if the duty cycle 60 is 50%, the
resulting resistance to flow will be 50% of the total resistance to
flow of the orifice 40. Similar respective results occur with the
30% and 90% duty cycles 60.
[0065] Turning now to FIG. 5, an agricultural spraying system 110
includes an electrically-actuated flow control system 114 including
a flow meter 162 and a flow regulating valve 172. Many of the
components of the agricultural spraying system 110 are similar to
the components of the foregoing embodiments as described above and
reference is made thereto for an enabling description of these
components if not expressly described below.
[0066] As in the previously described embodiment, a product S in
FIG. 5 flows from a tank 122 to a centrifugal pump 128 via a
suction pipe 130. As shown, the product S flows from the
centrifugal pump 128 to the flow regulating valve 172 via a
pressure pipe 170. The flow regulated product S flows to the flow
meter 162, to a pressure sensor 152, and to the direct acting
solenoid valve equipped nozzles 134 via a boom pipe 132. Thus, the
product S is delivered to a target such as the crop or ground P in
FIG. 1 via spray atomization nozzles 151 of the direct acting
solenoid valves 134.
[0067] More particularly, the flow meter 162 in FIG. 5 measures the
flow rate and sends a signal to a flow controller 164. The flow
controller 164 receives target rate information from a rate input
device 168 and speed from a speed input device 166. Accordingly,
the flow controller 164 controls the flow regulating valve 172 to
the desired rate. Additionally, the pressure sensor 152 measures
the pressure in the boom pipe 132 and sends the pressure
information to a pressure controller 154. The pressure controller
154 pulses the direct acting solenoid valve equipped nozzles 134
with a frequency and duty cycle which maintains a specific pressure
within the pipe 132.
[0068] The skilled artisan will appreciate that a conventional
flow-control system operates by shifting a flow control system
curve along a fixed pressure control curve. The intersection of the
two curves is the resultant conventional application flow and
pressure. As the flow changes in such a conventional system, the
intersection changes accordingly such that a new system pressure is
achieved as a direct result of the flow change.
[0069] FIG. 6 generally shows an interdependent relationship
between flow control and pressure control when an
electrically-actuated variable pressure control system is used in
conjunction with a flow control system. More specifically, FIG. 6
shows a relative, pressure-versus-flow relationship for liquid
flow-control systems, and an electrically-actuated variable
pressure control system as described above.
[0070] As shown in FIG. 6, an electrically-actuated pressure
control system according to the present invention allows a pressure
control curve 190 to be shifted in various directions indicated by
a double-headed arrow 194, which is an independent shift from a
change in a flow indicated by a double-headed arrow 192. The result
is that an intersection 196 may be navigated to any flow and
pressure setting desired by an operator, within limits of the
system. This ability, when controlled by flow and pressure
controllers, allows the operator to set flow and pressure set
points independently, and have both set points maintained
throughout a range of speed. In addition, the flow set point may be
changed without effecting the pressure set point, and vise
versa.
[0071] With reference now to FIGS. 5, 6 and 7, a control logic is
employed by the flow controller 164 and the electrically-actuated
variable pressure control system 154 according to an aspect of the
invention. In particular, FIG. 7 shows start-up of the flow control
system 164 at step A. A flow is read at step B, and a calculation
occurs to determine if the flow is too high or too low. This
calculation may be simple or complex depending on the variables
upon which flow is being controlled. As shown at step C, if the
flow is too low, a restriction is relieved by opening the flow
regulating valve 172 as in FIG. 5. Conversely, if the flow is too
high at step D, a restriction can be increased by closing the flow
regulating valve 172. The routine of reading and changing flow is
operated continuously while the flow-control system 164 is active.
Those skilled in the art will appreciate that alternate mechanisms
and methods of changing flow may be employed; for instance, by
using the ground driven positive pump 28 of FIG. 1, or by changing
the speed of the pump 28.
[0072] Also shown in FIG. 7, the control logic of the
electrically-actuated variable pressure control system 154 is
similar to that of the flow control system 164 described above.
Upon start-up of the pressure control system 154 at step F, a duty
cycle is initiated at step G at a desired value, which is 50% in
this example. This value can be set at a control panel 174 as
described below with respect to FIG. 8. The initiated value is held
for a predetermined or initiation time (step H) while the flow
control system 164 adjusts to the target flow. When the initiation
time is over, the pressure is read at step I. If the pressure is
too low, the resistance to flow is increased at step J by
decreasing the duty cycle 60 of the direct acting solenoid nozzle
134. Conversely, if the pressure is too high, the resistance to
flow is decreased at step K by increasing the duty cycle 60 of the
direct acting solenoid nozzle 134. When the pressure control system
154 is stopped, the initializing duty cycle is reset to the last
known duty cycle. This delay allows the flow control system 164 to
initialize and grants some priority to flow over pressure.
[0073] FIG. 8 shows an embodiment of the control panel 174, briefly
introduced above, for the electrically-actuated pressure control
system 154. The control panel 174 is mounted in a vehicle such as
in the cab 16 of the tractor 12 at FIG. 1 within reach of the
operator. In this example, a knob 176 is shown having twelve
detents 180. These twelve detents 180 indicate a target pressure
set point, or duty cycle, that the controller 154/164 is to
maintain.
[0074] As shown in FIG. 8, a mode of operation is dictated by a
switch 182. In this example, the three position switch 182 is off
in a center position, in a "PSI" mode in an uppermost position, and
in a "PWM %" mode in a downward position. Thus, the position of the
switch 182 in FIG. 8 indicates whether the knob 176 detent is
calibrated for PSI or PWM %. Making two modes of operation
available reduces down-time in the event of a system failure. For
instance, in PWM % mode, the system can be run from manually
calculated settings until the automatic pressure control system can
be repaired.
[0075] As further shown in FIG. 8, a color graphic 178 can be
utilized to guide the operator to more advantageous settings of the
knob 176. For instance, desirable ranges can be color coded green,
less desirable ranges can be yellow and ranges that should be used
sparingly or avoided can be colored orange or red.
[0076] Also shown in FIG. 8, a connector 184 is attached to a
wiring harness, which connects the panel 174 to other components of
the system 110. One skilled in the art will appreciate how the
connector 184 connects the panel 174 and further description is not
necessary to understand and practice this aspect of the
invention.
[0077] These and other modifications and variations to the present
invention may be practiced by those of ordinary skill in the art,
without departing from the spirit and scope of the present
invention. In addition, it should be understood that aspects of the
various embodiments may be interchanged either in whole or in part.
Furthermore, those of ordinary skill in the art will appreciate
that the foregoing description is by way of example only, and is
not intended to limit the invention.
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