Note: Descriptions are shown in the official language in which they were submitted.
Attorney Ref: 1057P067CA01
AGRICULTURAL PLANTING SYSTEM WITH AUTOMATIC DEPTH CONTROL
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Patent Application No. 15/856,875,
filed
December 28, 2017; U.S. Patent Application No. 15/637,692, filed June 29,
2017; and U.S.
Provisional Patent Application No. 62/648,183, filed March 26, 2018, each of
which are
hereby incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
This invention relates generally to agricultural planters and, more
particularly, to gauge
wheel load sensors and down pressure control systems for agricultural
planters.
BRIEF SUMMARY
In accordance with one embodiment, a control system for controlling the down
pressure
applied to a soil-engaging component of an agricultural implement includes a
source of
pressurized fluid, a down pressure actuator coupled to the soil-engaging
component and to
the source of pressurized fluid, an energy storage device and a piston-
containing cylinder
coupled to each other by a system containing pressurized fluid, a check valve
coupled
between the energy storage device and the down pressure actuator to control
the flow of the
pressurized fluid from the energy storage device to the cylinder, a
controllable relief valve
and a controllable variable orifice coupled between the down pressure actuator
and the
energy storage device to control the flow of the pressurized fluid from the
cylinder to the
energy storage device, a pressure sensor coupled to the pressurized fluid and
producing an
output signal corresponding to the pressure of the pressurized fluid, and a
controller coupled
to the pressure sensor to receive the output signal and configured to supply
control signals to
the controllable relief valve and the controllable variable orifice to control
the flow of the
pressurized fluid from the cylinder to the energy storage device based on the
pressure of the
pressurized fluid. The energy storage device is preferably an accumulator.
In one implementation, the controller supplies a control signal to the relief
valve to
open the relief valve in response to a predetermined change in the pressure of
the pressurized
fluid and also supplies a control signal to the variable orifice to control
the size of the orifice
when the relief valve is open, to control the rate of flow of pressurized
fluid from the energy
storage device to the cylinder.
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In accordance with another embodiment, a control system for controlling the
depth of
an opener device in an agricultural planter comprises a gauge wheel on a
pivotably mounted
support arm, a mechanical element coupled to the support arm to move in
response to
changes in the angle of the support arm, a sensor adapted to measure changes
in the relative
elevations of the opener device and the gauge wheel to produce an output
signal representing
the current relative elevations of the opener device and the gauge wheel, and
a control device
receiving the output signal from the sensor and producing a second output
signal for
maintaining the opener device at a selected elevation relative to the gauge
wheel.
Another implementation includes a moisture sensor producing a signal
representing the
moisture content of the soil being planted, and the control device is
responsive to the
moisture-representing signal for producing an output signal representing the
desired depth of
the opening device.
The sensor may translate the upward force from a pivoting gauge wheel support
arm
into a fluid pressure in a fluid chamber, and a pressure transducer may be
coupled to the fluid
chamber and produce an output signal that changes in proportion to changes in
the fluid
pressure in the fluid chamber. The control device may receive the output
signal and use that
output signal to produce a second output signal for maintaining said opener
device at a
selected elevation relative to said gauge wheel.
In yet another implementation, the control device supplies a control signal to
a relief
valve to open the relief valve in response to a predetermined change in the
pressure of the
pressurized fluid and also supplies a control signal to a variable orifice to
control the size of
the orifice when the relief valve is open, to control the rate of flow of
pressurized fluid to the
fluid chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical longitudinal section through a portion of an agricultural
planter that
includes a gauge wheel and an opener device.
FIG. 2 is an enlargement of the left side of FIG. I.
FIG. 3 is a bottom perspective of the control portion of the equipment shown
in FIG. 1.
FIG. 4 is an enlarged side elevation of the equipment shown in FIG. 3.
FIG. 5 is an enlarged top plan view of the equipment shown in FIG. 3.
FIG. 6 is an enlarged vertical longitudinal section through the equipment
shown in FIG.
3.
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FIG. 7 is a schematic diagram of a hydraulic control system for controlling
the
hydraulic system using a gauge wheel load sensor.
FIG. 8 is a schematic diagram of a modified hydraulic control system for
controlling
the hydraulic system using a gauge wheel load sensor.
FIG. 9 is a waveform diagram illustrating different modes of operation
provided by the
hydraulic control systems of FIGs. 7 and 8.
FIG. 10 is a plan view of a gauge wheel transducer system for an agricultural
planter
that includes a gauge wheel and an opener device.
FIG. 11 is a side elevation of the transducer system shown in FIG.10.
FIG. 12 is a sectional view taken along line A--A in FIG. 10.
FIG. 13 is a side elevation, partially in section, of the transducer system of
FIGs. 10-12
mounted on a gauge wheel and its supporting structure.
FIG. 14 is a perspective view of portions of the devices shown in FIG. 13.
FIG. 15 is a plan view similar to FIG. 10 but with portions removed to show
the
equalizer arm.
FIG. 16 is a plan view of a modified transducer system.
FIG. 17 is a longitudinal section taken along line 17--17 in FIG. 16.
FIG. 18A is a side elevation of a modified sensing system for detecting the
pressure
exerted on a pair of gauge wheels.
FIG. 18B is an end elevation of the system shown in FIG. 18A.
FIG. 19 is a schematic diagram of a hydraulic and electrical control system
for
controlling a down pressure actuator.
FIG. 20 is a schematic diagram of a first modified hydraulic and electrical
control
system for controlling a down pressure actuator.
FIG. 21 is a schematic diagram of a second modified hydraulic and electrical
control
system for controlling a down pressure actuator.
FIG. 22 is a schematic diagram of a third modified hydraulic and electrical
control
system for controlling a down pressure actuator.
FIG. 23 is a schematic diagram of a fourth modified hydraulic and electrical
control
system for controlling a down pressure actuator.
FIG. 24 is a flow chart of an exemplary algorithm executed by the controller
in the
system of FIG. 23.
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FIG. 25 is a schematic diagram of a fifth modified hydraulic and electrical
control
system for controlling a down pressure actuator.
FIG. 26 is sectional elevation of a modified embodiment of an automatic depth
control
system.
FIG. 27 is a reduced version of the control system of FIG. 26 positioned
adjacent a
gauge wheel and its support arm.
FIG. 28 is a perspective view of the gauge wheel and control system shown in
FIG. 27
FIG. 29 is an enlarged top plan view of the gauge wheel and control system
shown in
FIG.28.
FIG. 30 is a side elevation of the control system shown in FIG. 26.
FIG. 31 is an enlarged section taken along line 31-31 in FIG. 30.
FIG. 32 is an enlarged section taken along line 32-32 in FIG. 30.
FIG. 33 is an enlarged view of the slider/depth adjuster in the control system
of FIG.
30, with the slider/depth adjuster in two different positions.
FIG. 34 is a flow chart of an algorithm for use in the control system of FIGs.
26-33.
DETAILED DESCRIPTION
An agricultural planter typically includes a number of individual row units,
each of
which includes its own row cleaner device, row opener device and row closing
device. The
down pressure is typically controlled separately for each row unit or each of
several groups of
row units, and is preferably controlled separately for one or more of the
individual devices in
each row unit, as described in more detail in pending U.S. application Serial
No. 14/146,822
filed January 3, 2014, which is incorporated by reference herein in its
entirety.
FIGs. 1-6 illustrate an improved gauge wheel load sensor that takes the upward
force
from a pivoting planter gauge wheel support, such as the pivoting support arms
10 in the row
unit equipment shown in FIGs. 1 and 2, and translates that force into a fluid
pressure in a
fluid chamber 11. The gauge wheel support arms push against an equalizer
support 12,
which is connected to a slider 13 that slides along an arcuate guide 14.
Movement of the
slider along the guide 14 moves one end of a connector arm 15 that is attached
at its other end
to a rocker arm 16 mounted for pivoting movement abound a stationary pivot pin
17. The
lower end of the rocker arm 16 engages a ram 18 in a hydraulic cylinder 19
that is filled with
a pressurized hydraulic fluid.
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Depth adjustment is accomplished in the conventional sense by pivoting the
assembly
around a pivot 20, and locking a handle 21 into the desired position with a
mechanism 22.
With this design it is preferred that that there is no air trapped in the
fluid chamber 11. For
this reason the mechanism includes a bleed valve 23. The process for removal
of air is to
extend the ram to the maximum extent with calibration/travel limiter plates 24
(FIG. 4)
removed. The system is then filled completely with fluid with the bleed valve
23 closed.
Then the bleed valve 23 is opened, and the rocker arm 14 is pushed against the
ram 16 to
move the ram to the exact place where the calibration/travel limit plates 24
allow a
calibration plate retaining screw 25 to fit into a hole. This ensures that
each assembly is set
the same so all the row units of the planter are at the same depth. At this
point the bleed
valve 23 is closed. With all air removed, the mechanical/fluid system will act
as a rigid
member against forces in compression. The travel limiter plate 24 keeps a cam
pivot
weldment from falling down when the planter is lifted off the ground.
Standard industry practice is to use a strain gauge to directly measure the
planter gauge
wheel load. The design shown in FIGs. 1-6 is an improvement over the state of
the art
because it allows the sensor to measure only the down force on the gauge
wheels. In typical
designs using strain gauge type sensors, the mechanical linkage that allows
the gauge wheels
to oscillate causes the measured wheel force to have substantial noise due to
changes in the
force being applied. For this reason it can be difficult to determine which
parts of the signal
correspond to actual changes in down force on the gauge wheels, versus signal
changes that
are due to movement of components of the gauge wheel support mechanism. The
reason for
this is that strain gauge sensors will only measure the force that is being
applied in a single
plane. Because of the linkage and pivot assembly that is used on typical
planters, the force
being applied to the strain gauge type designs can change based on the depth
setting or
whether the planter gauge wheels are oscillating over terrain. In this way
they will tend to
falsely register changes in gauge wheel down force and make it difficult to
have a closed loop
down pressure response remain consistent.
The fluid seal of the pressure sensor described here creates friction in the
system which
has the effect of damping out high frequency noise. Agricultural fields have
very small scale
variations in the surface which cause noise to be produced in the typical down
force sensor
apparatus. By using fluid pressure this invention decouples the sensor from
the mechanical
linkage and allows the true gauge wheel force to be more accurately measured.
Lowering the
amount of systematic noise in the gauge wheel load output sensor makes it
easier to produce
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an automatic control system that accurately responds to true changes in the
hardness of the
soil, as opposed to perceived changes in soil hardness due to noise induced on
the sensor.
FIG. 7 is a schematic diagram of a hydraulic control system for any or all of
the
hydraulic actuators in a down pressure control system. The hydraulic cylinder
2600 is
supplied with pressurized hydraulic fluid from a source 2601 via a first
controllable two-
position control valve 2602, a restriction 2603 and a check valve 2604. The
pressurized
hydraulic fluid supplied to the cylinder 2600 can be returned from the
cylinder to a sump
2605 via a second controllable two-position control valve 2606, a restriction
2607 and a
check valve 2608. Both the control valves 2602 and 2606 are normally closed,
but can be
opened by energizing respective actuators 2609 and 2610, such as solenoids.
Electrical
signals for energizing the actuators 2609 and 2610 are supplied to the
respective actuators via
lines 2611 and 2612 from a controller 2613, which in turn may be controlled by
a central
processor 2614. The controller 2613 receives input signals from a plurality of
sensors, which
in the example of FIG. 7 includes a pressure transducer 2615 coupled to the
hydraulic
cylinder 2600 via line 2616, and a ground hardness sensor 2617. An accumulator
2618 is
also coupled to the hydraulic cylinder 2600, and a relief valve 2619 connects
the hydraulic
cylinder 2600 to the sump 2605 in response to an increase in the pressure in
the cylinder 2600
above a predetermined level.
To reduce the energy required from the limited energy source(s) available from
the
tractor or other propulsion device used to transport the row units over an
agricultural field,
the control valves 2602 and 2606 are preferably controlled with a pulse width
modulation
(PWM) control system implemented in the controller 2613. The PWM control
system
supplies short-duration (e.g., in the range of 50 milliseconds to 2 seconds
with orifice sizes in
the range of 0.020 to .2 inch) pulses to the actuators 2609 and 2610 of the
respective control
valves 2602 and 2606 to open the respective valves for short intervals
corresponding to the
widths of the PWM pulses. This significantly reduces the energy required to
increase or
decrease the pressure in the hydraulic cylinder 2600. The pressure on the exit
side of the
control valve is determined by the widths of the individual pulses and the
number of pulses
supplied to the control valves 2602 and 2606. Thus, the pressure applied to
the hydraulic
cylinder 2622 may be controlled by separately adjusting the two control valves
2602 and
2606 by changing the width and/or the frequency of the electrical pulses
supplied to the
respective actuators 2609 and 2610, by the controller 2613. This avoids the
need for a
constant supply current, which is a significant advantage when the only
available power
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source is located on the tractor or other vehicle that propels the soil-
engaging implement(s)
across a field.
The hydraulic control system of FIG. 7 may be used to control multiple
hydraulic
cylinders on a single row unit or a group of row units, or may be replicated
for each
individual hydraulic cylinder on a row unit having multiple hydraulic
cylinders. For
example, in the system described above having a ground hardness sensor located
out in front
of the clearing wheels, it is desirable to have each hydraulic cylinder on any
given row unit
separately controlled so that the down pressure on each tool can be adjusted
according to the
location of that tool in the direction of travel. Thus, when the ground
hardness sensor detects
a region where the soil is softer because it is wet, the down pressure on each
tool is preferably
adjusted to accommodate the softer soil only during the time interval when
that particular tool
is traversing the wet area, and this time interval is different for each tool
when the tools are
spaced from each other in the direction of travel. In the case of a group of
row units having
multiple hydraulic cylinders on each row unit, the same hydraulic control
system may control
a group of valves having common functions on all the row units in a group.
FIG. 8 is a schematic diagram of a modified hydraulic control system that uses
a single
three-position control valve 2620 in place of the two two-position control
valves and the two
check valves used in the system of FIG. 7. The centered position of the valve
2620 is the
closed position, which is the normal position of this valve. The valve 2620
has two actuators
2620a and 2620b, one of which moves the valve to a first open position that
connects a
source 2621 of pressurized hydraulic fluid to a hydraulic cylinder 2622 via
restriction 2620c,
and the other of which moves the valve to a second open position that connects
the hydraulic
cylinder 2622 to a sump 2623. Electrical signals for energizing the actuators
2620a and
2620b are supplied to the respective actuators via lines 2624 and 2625 from a
controller 2626,
which in turn may be controlled by a central processor 2627. The controller
2626 receives
input signals from a pressure transducer 2628 coupled to the hydraulic
cylinder 2622 via line
2629, and from an auxiliary sensor 2630, such as a ground hardness sensor. An
accumulator
2631 is coupled to the hydraulic cylinder 2622, and a relief valve 2632
connects the hydraulic
cylinder 2622 to the sump 2623 in response to an increase in the pressure in
the cylinder 2622
above a predetermined level.
As depicted in FIG. 9, a PWM control system supplies short-duration pulses P
to the
actuators 2620a and 2620b of the control valve 2620 to move the valve to
either of its two
open positions for short intervals corresponding to the widths of the PWM
pulses. This
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significantly reduces the energy required to increase or decrease the pressure
in the hydraulic
cylinder 2622. In FIG. 9, pulses PI-P3, having a voltage level VI, are
supplied to the
actuator 2620b when it is desired to increase the hydraulic pressure supplied
to the hydraulic
cylinder 2622. The first pulse PI has a width Ti which is shorter than the
width of pulses P2
and P3, so that the pressure increase is smaller than the increase that would
be produced if P1
had the same width as pulses P2 and P3. Pulses P4-P6, which have a voltage
level V2, are
supplied to the actuator 2620a when it is desired to decrease the hydraulic
pressure supplied
to the hydraulic cylinder 2622. The first pulse P4 has a width that is shorter
than the width
T2 of pulses P2 and P3, so that the pressure decrease is smaller than the
decrease that would
be produced if P4 had the same width as pulses P5 and P6. When no pulses are
supplied to
either of the two actuators 2620a and 2620b, as in the "no change" interval in
FIG. 9, the
hydraulic pressure remains substantially constant in the hydraulic cylinder
2622.
FIGs. 10-15 illustrate a modified gauge wheel load sensor that includes an
integrated
accumulator 122. The purpose of the accumulator 122 is to damp pressure spikes
in the
sensor when the planter is operating at low gauge wheel loads. When the forces
that the
gauge wheel support arms 110 are exerting on the hydraulic ram 117 are near
zero, it is more
common for the surface of the soil or plant residue to create pressure spikes
that are large in
relation to the desired system sensor pressure. These pressure spikes produce
corresponding
changes in the vertical position (elevation) of the gauge wheels. As the
target gauge wheel
down force increases, and consequently the pressure in the fluid chamber III
and the
transducer output voltage from sensor 118, the small spikes of pressure due to
variations in
the soil surface or plant residue decrease proportionally.
In the present system, rather than have a perfectly rigid fluid coupling
between the ram
117 and the pressure transducer 118, as load increases on the ram 117, the
fluid first pushes
against a piston 125 of the accumulator 122 that is threaded into a side
cavity 123 in the same
housing that forms the main cavity for the ram 117. The increased pressure
compresses an
accumulator spring 126 until the piston 125 rests fully against a shoulder on
the interior wall
of the accumulator housing 127, thus limiting the retracting movement of the
accumulator
piston 125. At this point, the system becomes perfectly rigid. The amount of
motion
permitted for the accumulator piston 125 must be very small so that it does
not allow the
depth of the gauge wheel setting to fluctuate substantially. The piston
accumulator (or other
energy storage device) allows the amount of high frequency noise in the system
to be reduced
at low gauge-wheel loads. Ideally an automatic down pressure control system
for an
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agricultural planter should maintain a down pressure that is as low as
possible to avoid over
compaction of soil around the area of the seed, which can inhibit plant
growth. However, the
performance of most systems degrades as the gauge wheel load becomes close to
zero,
because the amount of latent noise produced from variation in the field
surface is large in
relation to the desired gauge wheel load.
Planter row units typically have a gauge wheel equalizer arm 130 that is a a
single
unitary piece. It has been observed that the friction between the equalizer
arm 130 and the
gauge wheel support arms 110, as the gauge wheel 115 oscillates up and down,
can generate
a substantial amount of noise in the sensor. At different adjustment
positions, the edges of
the equalizer arm 130 contact the support arms 10 at different orientations
and can bite into
the surface and prevent forces from being smoothly transferred as they
increase and decrease.
When the equalizer arm 130 is a single unitary piece, there is necessarily a
high amount of
friction that manifests itself as signal noise in the sensor. This signal
noise makes it difficult
to control the down pressure system, especially at low levels of gauge wheel
load.
To alleviate this situation, the equalizer arm 130 illustrated in FIG. 16 has
a pair of
contact rollers 131 and 132 are mounted on opposite ends of the equalizer arm.
These rollers
131 and 132 become the interface between the equalizer arm and the support
arms 110,
allowing forces to be smoothly transferred between the support arms 110 and
the equalizer
arm 130. The roller system allows the gauge wheel support arms 110 to
oscillate relative to
each other without producing any sliding friction between the support arms 110
and the
equalizer arm 130. This significantly reduces the friction that manifests
itself as signal noise
in the sensor output, which makes it difficult to control the down pressure
control system,
especially at low levels of gauge wheel load.
FIG. 17 is a longitudinal section through the device of FIG. 16, with the
addition of a
rocker arm 150 that engages a ram 151 that controls the fluid pressure within
a cylinder 152.
A fluid chamber 153 ladjacent the inner end of the ram 151 opens into a
lateral cavity that
contains a pressure transducer 154 that produces an electrical output signal
representing the
magnitude of the fluid pressure in the fluid chamber 153. The opposite end of
the cylinder
152 includes an accumulator 155 similar to the accumulator 125 included in the
device of
FIG. 9 described above. Between the fluid chamber 153 and the accumulator 155,
a pair of
valves 156 and 157 are provided in parallel passages158 and 159 extending
between the
chamber 153 and the accumulator 155. The valve 156 is a relief valve that
allows the
pressurized fluid to flow from the chamber 153 to the accumulator 155 when the
ram 151
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advances farther into the chamber 153. The valve 157 is a check valve that
allows
pressurized fluid to flow from the accumulator 155 to the chamber 153 when the
ram 151
moves outwardly to enlarge the chamber 153. The valves 156 and 157 provide
overload
protection (e.g., when one of the gauge wheels hits a rock) and to ensure that
the gauge
wheels retain their elevation setting.
FIGs. 18A and 18B illustrate a modified sensor arrangement for a pair of gauge
wheels
160 and 161 rolling on opposite sides of a furrow 162. The two gauge wheels
are
independently mounted on support arms 163 and 164 connected to respective rams
165 and
166 that control the fluid pressure in a pair of cylinders 167 and 168. A
hydraulic hose 169
connects the fluid chambers of the respective cylinders 167 and 168 to each
other and to a
common pressure transducer 170, which produces an electrical output signal
corresponding to
the fluid pressure in the hose 169. The output signal is supplied to an
electrical controller that
uses that signal to control the down forces applied to the two gauge wheels
160 and 161. It
will be noted that the two gauge wheels can move up and down independently of
each other,
so the fluid pressure sensed by the transducer 170 will be changed by vertical
movement of
either or both of the gauge wheels 160 and 161.
FIGs. 19-22 illustrate electrical/hydraulic control systems that can be used
to control a
down-pressure actuator 180 in response to the electrical signal provided to a
controller 181 by
a pressure transducer 182. In each system the transducer 182 produces an
output signal that
changes in proportion to changes in the fluid pressure in a cylinder 183 as
the position of a
ram 184 changes inside the cylinder 183. In FIG. 19, the pressurized fluid
chamber in the
cylinder 183 is coupled to an accumulator 185 by a relief valve 186 to allow
pressurized fluid
to flow to the accumulator, and by a check valve 187 to allow return flow of
pressurized fluid
from the accumulator to the cylinder 183. In FIG. 20, the accumulator 185 is
replaced with a
pressurized fluid source 188 connected to the check valve 187, and a sump 189
connected to
the relief valve 186. In FIG. 21, the accumulator 185 is connected directly to
the pressurized
fluid chamber in the cylinder 183, without any intervening valves. In the
system of FIG. 22,
there is no accumulator, and the pressure sensor 182 is connected directly to
the pressurized
fluid chamber in the cylinder 183.
FIG. 23 illustrates a modified electrical/hydraulic control system for
controlling a
down-pressure actuator 200 in response to an electrical signal provided to a
controller 201 by
a pressure transducer 202. The transducer 202 produces an output signal that
changes in
proportion to changes in the fluid pressure in a cylinder 203 as the position
of a ram 204
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changes inside the cylinder 203. Thus the ram 204 functions as a gauge wheel
sensor. The
pressurized fluid chamber in the cylinder 203 is coupled to an accumulator 205
by a
controllable valve 206 to allow pressurized fluid to flow to the accumulator
205 through a
controllable variable orifice 207, and by a check valve 208 to allow return
flow of pressurized
fluid from the accumulator 205 to the cylinder 203.
When the force applied to the piston 204, e.g., by the rocker arm 14,
increases when the
ground-engaging implement encounters harder ground or strikes a rock, the
piston 204 is
moved to the left. This causes a portion of the pressurized fluid to flow
through the variable
orifice 207 and the relief valve 206 to the accumulator 205. Both the variable
orifice 207 and
the relief valve 206 are controlled by electrical control signals from the
controller 201, which
receives the output signal from the pressure sensor 202.
The variable orifice 207 acts as an adjustable and controllable damper
affecting the
stiffness of, for example, a planter gauge wheel suspension. Also, the electro-
proportional
relief valve 206 allows the stiffness of, for example, a planter row unit ride
to be changed
dynamically. For example, the controller 201 can be programmed to allow a
stiffer setting or
higher relief pressure in smooth fields. In rougher fields, the relief
pressure can be reduced to
allow more travel of the gauge wheels relative to the opener disks. This
results in less
bouncing of the row unit. The amount of variation in the pressure sensor
output signal
reflects variations in the roughness of the field. The controller can use this
variation or
smoothness of the pressure signal over time to control the relief pressure in
real time.
When the force applied to the piston is reduced, the fluid pressure within the
cylinder
203 is reduced, and the accumulator causes a portion of the fluid to flow back
into the
cylinder 203 via the check valve 208. The reduced pressure is sensed by the
pressure sensor
202, which produces a corresponding change in the sensor output signal
supplied to the
controller 201.
The controller 201 is programmed with an algorithm represented by the flow
chart in
FIG. 24. The first step 250 selects a predetermined system "mapping" of
variables such as
the diameter of the variable orifice 207 and relief pressure in the cylinder
203. Other
variables such as the down pressure control system set point can be included
in the mapping.
The mapping is based on tillage and soil conditions that lead to typical
characteristics in the
sensor data. After the mapping of the selected variables, a field operation
such as planting,
fertilizing or tillage, is started at step 251, and at step 252 the pressure
transducer 202
supplies the controller 201 with a signal that varies with the fluid pressure
in the cylinder
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203, which corresponds to changes in the gauge wheel load. The controller 201
computes a
running average value of the gauge wheel load for a selected time period at
step 253, and at
step 254 supplies a control signal to the down-pressure actuator 200 to
control the down
pressure in a closed loop.
In parallel with the closed loop control of the down-pressure actuator 200,
the
controller also adjusts the values of the mapped variables in steps 255-259.
Step 255
performs a statistical analysis of the gauge wheel sensor values to determine
the signal-to-
noise ratio ("SNR"), of the level of the desired signal to the level of
background noise in the
gauge wheel down pressure signal. The SNR can be determined by any of the
known
standard procedures, such as determining the ratio of the arithmetic mean to
the standard
deviation. The controller then determines whether the current SNR is above or
below a
preselectd value, at steps 256 and 257. If the SNR is determined to be above
the preselected
value at step 256, step 258 adjusts the mapped values to reduce the target set
point and the
orifice diameter and to increase the relief pressure. If the SNR is below the
preselected value
at step 257, step 259 adjusts the mapped values to increase the target set
point and the orifice
diameter and to decrease the relief pressure.
FIG. 25 illustrates a modified control system in which the relief valve 206 is
replaced
with a controllable 3-way valve 306, and a sump 309 and a pressure supply pump
310 are
connected to the valve 306. This control system also includes a position
sensor 312, such as
an inductive sensor or a linear encoder, which supplies the controller 301
with a signal
representing the position of the piston 304 within the cylinder 303. The
signal from the
position sensor 302 enables the controller 301 to identify in real time the
depth of the opener
relative to the gauge wheel.
When the 3-way valve 306 is in its center position, as shown in FIG. 25, the
cylinder
303 is disconnected from both the sump 309 and the pump 310, and thus the
cylinder 303 is
coupled to the accumulator 305 via the variable orifice 307. This is the
normal operating
position of the valve 306. When the controller 301 produces a signal that
moves the valve
306 to the right, the valve connects the cylinder 303 to the pressure supply
pump 310 to
increase the fluid pressure in the cylinder 303 to a desired level. When the
controller 301
produces a signal that moves the valve 306 to the left, the valve connects the
cylinder 303 to
the sump 309 to relieve excessive pressure in the cylinder 303.
The system in FIG. 25 allows active control of the depth of the ground-
engaging
element by using the pressure control valve 306 to change the pressure in the
cylinder 303.
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Because the piston 304 is connected to the gauge wheel arms via the rocker,
the gauge wheels
move relative to the opener disks as the piston 304 moves in and out.
When planting an agricultural field with seeds, it is important to control the
planting
depth in real time as the planting machine traverses the field, because it is
critical that the
seeds all be planted into moisture so that each seed emerges from the soil at
the same time.
The depth of the seed can be changed based on some type of moisture sensor
system, or even
based on a satellite or drone system that is able to detect changes in the
soil chemistry that
would make it desirable to change the depth of the planted seed in different
areas of the field.
FIG. 26 illustrates a modified system that enables the operator to select a
desired
planting depth setting, and then automatically maintains the actual planting
depth within a
selected range above and below the selected depth. In this system, a fluid
chamber 408
includes a fluid port 420 (see FIGs. 30 and 31) that is connected to one or
more valves to
allow hydraulic fluid to be added to or removed from the chamber 408 to change
the angle of
the opener disc relative to the gauge wheel. A distance sensor 411 produces an
output signal
representing the position of the opener disc support arm along the arcuate
guide, which
changes as the angle between the two support arm changes with changes in the
depth of the
opener disc relative to the elevation of the gauge wheel (the soil surface).
The output signal
from the distance sensor 411 will be referred to as the "seed depth" signal
because the depth
of the opener disc determines the depth of the furrow in which the seed is
planted.
In one embodiment that provides both environmental protection and low cost, a
pair of
valves are controlled to open and close to extend or retract the ram of a
hydraulic cylinder to
move a slider/depth adjuster to the desired position. If the position of the
slider/depth adjuster
falls out of tolerance, the system automatically opens and closes the valve to
maintain the
correct setting. Each row unit may be provided with its own valves and
associated control
system. This design may use a small hydraulic ram 406 to perform what would
typically be a
manual depth adjustment. The ram 406 pushes on a rocker arm 404, which is
connected to a
link arm 410, which is connected to a slider piece 412. The slider piece 412
is connected to
the planter row unit depth adjustment handle and is free to move throughout
the same
adjustment range that the handle could be moved manually to effect a depth
adjustment.
The pressure inside the chamber 408 is equivalent to the force on the gauge
wheels.
Thus, a single device can provide both depth adjustment and gauge wheel force
measurement, without the need for the typical strain gauge. The system allows
fluid pressure
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to be used both to change the depth that the seed is planted in the ground and
how hard the
planter gauge wheels are pushing on the ground in a single device.
In the illustrative system, the fluid port 420 in the fluid chamber 408 is
connected to
one or more valves to allow hydraulic fluid to be added to or removed from the
chamber 408
to change the angle of the opener disc relative to the gauge wheel for any
given soil
condition.
The distance sensor 411 produces an output signal corresponding to the
position of the
piston within the hydraulic cylinder, which changes when the depth of the
opening disc
changes relative to the elevation of the gauge wheel. For example, if the soil
engaged by the
opening disc becomes harder, the depth of the opening disc becomes smaller
unless the down
pressure applied to the opening disc is increased. Conversely, if the soil
engaged by the
opening disc becomes softer, the depth of the opening disc becomes greater
unless the down
pressure applied to the opening disc is decreased. Thus, the position signal
from the
hydraulic cylinder actually represents the depth of the opening disc.
The small hydraulic ram 406 performs what would typically be a manual depth
adjustment. The ram 406 pushes on a rocker arm 404, which is connected to a
link arm 410,
which is connected to a slider/depth adjuster 412. The slider/depth adjuster
412 is free to
move through the same adjustment range that the conventional depth adjustment
handle could
be moved manually to effect a depth adjustment.
The inductive distance sensor 411 that moves closer or farther away from a
metal cam
target 424 as the slider/depth adjuster 412 is moved throughout its adjustment
range. The
distance sensor 411 produces an output signal that is sent to an electronic
controller that
compares the signal from the distance sensor 411 with a desired depth value
entered by the
operator of the planter, as described in more detail below. A variety of
linear or angular
position sensors could be used in place of the illustrated distance sensor,
which is preferred
for its environmental protection and low cost.
As a controller compares the actual depth with the desired depth, it produces
an output
signal that controls a pair of valves that can be opened and closed to adjust
the pressure in the
hydraulic cylinder that receives the ram 406. Changing this pressure extends
or retracts the
ram 406 to move the slider/depth adjuster 412 to the desired position. Thus,
if the position of
the ram 406 falls out of tolerance, the system will automatically open and
close the valves to
maintain the correct setting.
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Also provided is a pressure sensor 415 that measures the pressure inside a
hydraulic
cylinder 408 that receives the ram 406. It can be seen that the force exerted
on the ground by
the gauge wheels is transmitted from the tires to the gauge wheel arms 407,
both of which
pivot and are supported by the pivoting equalizer 400. This equalizer 400 is
connected to the
slider/depth adjuster 412, which is connected to the link arm 410, which is
connected to the
rocker arm 404, which in turn contacts the ram 406, which in turn compresses
the fluid in the
cylinder 406, which is measured by a pressure sensor 415. Thus, the pressure
inside the
cylinder 406 is equivalent to the force on the gauge wheels. In this way, a
single device
accomplishes both depth adjustment and gauge wheel force measurement, and
eliminates the
need for the typical strain gauge.
When planting an agricultural field with seeds, it is important to control the
planting
depth in real time as the planting machine traverses the field, because it is
critical that the
seeds all be planted into moisture so that each seed emerges from the soil at
the same time.
The depth of the seed can be changed based on some type of moisture sensor
system, or even
based on a satellite or drone system that is able to detect changes in the
soil chemistry that
would make it desirable to change the depth of the planted seed in different
areas of the field.
An objective of the present invention is to provide a planting system that
enables the
operator to select a desired planting depth setting, and then automatically
maintains the actual
planting depth within a selected range above and below the selected depth.
In one embodiment that provides both environmental protection and low cost, a
pair of
valves are controlled to open and close to extend or retract the ram of a
hydraulic cylinder to
move a slider/depth adjuster to the desired position. If the position of the
slider/depth
adjuster falls out of tolerance, the system automatically opens and closes the
valve to
maintain the correct setting. Each row unit may be provided with its own
valves and
associated control system.
The pressure inside the cylinder 408 is equivalent to the force on the gauge
wheels.
Thus, a single device can provide both depth adjustment and gauge wheel force
measurement, without the need for the typical strain gauge. The system allows
fluid pressure
to be used both to change the depth that the seed is planted in the ground and
how hard the
planter gauge wheels are pushing on the ground in a single device.
In the illustrative system, a fluid port 420 in the fluid chamber 408 is
connected to one
or more valves to allow hydraulic fluid to be added to or removed from the
chamber 408 to
change the angle of the opener disc relative to the gauge wheel.
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The distance sensor 411 produces an output signal representing the position of
the
cutting wheel support arm along the arcuate slot. That position changes as the
angle between
the two support arm changes with changes in the depth of the opener disc
relative to the
elevation of the gauge wheel (the soil surface). The output signal from the
distance sensor
411 will be referred to as the "seed depth" signal because the depth of the
opener disc
determines the depth of the furrow in which the seed is planted.
The position sensor produces an output signal corresponding to the position of
the
piston within the hydraulic cylinder, which changes when the depth of the
opener disc
changes relative to the elevation of the gauge wheel. For example, if the soil
engaged by the
opening disc becomes harder, the depth of the opening disc becomes smaller
unless the down
pressure applied to the opening disc is increased. Conversely, if the soil
engaged by the
opening disc becomes softer, the depth of the opening disc becomes greater
unless the down
pressure applied to the opening disc is decreased. Thus, the position signal
from the
hydraulic cylinder actually represents the depth of the opening disc.
The output signal from the position sensor is supplied to the controller,
which
determines whether any change in that signal falls within predetermined dead
bands on
opposite sides of the target value. If a change exceeds a dead band, the
controller produces a
control signal that increases or decreases the down pressure on the opening
disc to maintain
the depth of the opening disc within a desired range on both sides of the
target value.
The target value can be changed automatically as the planter traverses a field
having
variable soil conditions. For example, a soil moisture sensor cane be used to
determine
optimum target values in different areas of a field being planted. Another
example is to use
stored data corresponding to the soil properties at different GPS locations in
the field to
adjust the target value as the planter traverses those locations.
The gauge wheel support arms 400 push against an equalizer support which is
connected to the slider/depth adjuster 412 that slides along an arcuate guide
412. Movement
of the slider/depth adjuster 412 along the arcuate guide moves one end of the
link arm 410
that is attached at its other end to the rocker arm 408 mounted for pivoting
movement abound
a stationary pivot pin 405. The lower end of the rocker arm 408 engages the
ram 406 in the
hydraulic cylinder 408 that is filled with a pressurized hydraulic fluid.
The force on the gauge wheels due to the weight of the row unit and applied
down force
causes the rocker arm 404 to pivot around the pivot bolt 405 and push against
the hydraulic
ram 406. This force on the ram 406 controls the pressure on the fluid in the
cylinder 408, so
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the fluid pressure in the cylinder 408 is proportional to the amount of gauge
wheel load. This
fluid pressure controls the depth of the opener blade by controlling the angle
between the
support arms for the gauge wheel and the opener blade.
To adjust the depth of the opener blade, the pressure of the hydraulic fluid
in the
cylinder 408 can be adjusted by increasing or decreasing the amount of
hydraulic fluid in the
cylinder. This is accomplished by a pair of valves that can be opened and
closed by electrical
signals from an electrical controller.
The fluid cylinder 408 includes a fluid port 420 that is connected to one or
more valves
to allow hydraulic fluid to be added to or removed from the cylinder 408 to
change the angle
of the opener disc relative to the gauge wheel. The distance sensor 411
produces an output
signal representing the position of the opener disc support arm 402 along an
arcuate guide,
which changes as the angle between the two support arms changes with changes
in the depth
of the opener disc relative to the elevation of the gauge wheel (the soil
surface). The output
signal from the distance sensor 411 can be referred to as the "seed depth"
signal because the
depth of the opener disc determines the depth of the furrow in which the seed
is planted.
FIG. 34 is a flow chart of an algorithm for generating signals that control
the one or
more valves that control the flow of hydraulic fluid in and out of the fluid
chamber 408. At
step 488, this algorithm calibrates the distance or angle sensor to read the
correct seed depth
in inches, and step 490 calibrates the pressure sensor 415 to read the gauge
wheel force in
pounds or kilograms. Step 492 computes the target seed depth and down pressure
based on
the output of step 491 and external soil property data, furrow hardness sensor
data and/or
moisture sensor data. Then seed depth dead band values are entered at step
493, and down
pressure dead band values are entered at step 494.
Step 500 in this algorithm determines whether the planter row unit is in an
operating
configuration on the ground, as will be described in detail below. When step
500 produces
an affirmative answer, step 501 measures the actual seed depth, and step 502
measures the
actual gauge wheel load. Steps 503 and 504 then determine whether the actual
seed depth
and the actual gauge wheel load are within their respective dead bands and, if
the answer is
negative in either case, whether the actual value is above or below that dead
band.
In the case of the seed depth, if the actual seed depth is within the dead
band, the
system returns to step 500 to repeat steps 501-504. If the actual seed depth
is outside the dead
band and is too deep, step 505 opens a valve to supply additional hydraulic
fluid to the
cylinder 406 for a brief time interval. If the actual seed depth is outside
the dead band and
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too shallow, step 505 opens a valve to allow hydraulic fluid to flow out of
the cylinder 408
for a brief time interval.
In the case of the gauge wheel load, if the actual gauge wheel load is above
the dead
band, step 505 opens a valve to supply additional hydraulic fluid to the
cylinder 408. If the
actual gauge wheel load is above the dead band, step 507 decreases the down
pressure
actuator pressure. If the actual gauge wheel load is below the dead band, step
108 increases
the down pressure actuator pressure. If the actual gauge wheel load is within
the dead band,
the system returns to step 500 to repeat steps 501-504.
When step 500 produces a negative answer, step 509 performs an active air
purge
process, and step 510 maintains the row unit down pressure at zero for safety.
According to Embodiment Al, a control system is directed to controlling the
depth of
an opener device in an agricultural planter. The system includes a gauge wheel
on a
pivotably mounted support arm; a mechanical element coupled to the support arm
to move in
response to changes in the angle of the support arm; a sensor adapted to
measure changes in
the relative elevations of the opener device and the gauge wheel to produce an
output signal
representing the current relative elevations of the opener device and the
gauge wheel; and a
control device receiving the output signal from the sensor,and producing a
second output
signal for maintaining the opener device at a selected elevation relative to
the gauge wheel.
According to Embodiment A2, the control system of Embodiment Al includes a
moisture sensor producing a signal representing the moisture content of the
soil being
planted, and the controller is responsive to the moisture-representing signal
for producing an
output signal representing the desired depth of the opening device.
According to Embodiment A3, the control system of Embodiment Al has the sensor
translating the upward force from a pivoting gauge wheel support arm into a
fluid pressure in
a fluid chamber.
According to Embodiment A4, the control system of Embodiment A3 has the fluid
pressure being proportional to the gauge wheel load.
According to Embodiment AS, the control system of Embodiment A3 includes a
pressure transducer coupled to the fluid chamber and produces an output signal
that changes
in proportion to changes in the fluid pressure in the fluid chamber, the
control device
receiving the output signal and using that output signal to produce the second
output signal.
According to Embodiment A6, a method is directed to controlling the depth of
an
opener device in an agricultural planter having a gauge wheel on a pivotably
mounted support
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arm, the method comprising: in response to changes in the angle of the support
arm, moving a
mechanical element coupled to the support arm; producing a first output signal
representing
the current relative elevations of the opener device and the gauge wheel, in
response to
changes in the relative elevations of the opener device and the gauge wheel;
and in response
to the first output signal, producing a second output signal for maintaining
the opener device
at a selected elevation relative to the gauge wheel.
According to Embodiment A7, the method of Embodiment A6 includes producing a
signal representing the moisture content of the soil being planted, and in
response to the
moisture-representing signal, producing an output signal representing the
desired depth of the
opening device.
According to Embodiment A8, the method of Embodiment A6 has the upward force
from a pivoting gauge wheel support arm being translated into a fluid pressure
in a fluid
chamber.
According to Embodiment A9, the method of Embodiment A8 has the fluid pressure
being proportional to the gauge wheel load.
According to Embodiment A10, the method of Embodiment A8 includes producing an
output signal that changes in proportion to changes in the fluid pressure in
the fluid chamber,
and using that output signal to produce the second output signal.
According to Embodiment Bl, a gauge wheel load sensor for an agricultural
planter has
a row unit that includes a pivotably mounted gauge wheel and a down pressure
controller for
controlling the down pressure on at least a portion of the row unit, the load
sensor
comprising: a mechanical element mounted for movement in response to the
downward force
applied to the row unit; a fluid-containing device containing an element
coupled to the
mechanical element for changing the fluid pressure in the fluid-containing
device in response
to the movement of the mechanical element; and a transducer coupled to the
fluid-containing
device for producing an output signal in response to changes in the fluid
pressure.
According to Embodiment B2, the gauge wheel load sensor of Embodiment B1 has
the
mechanical element being a rocker arm coupled to the gauge wheel so that the
pressure on a
ram within the cylinder is adjusted in response to vertical movement of the
gauge wheel.
According to Embodiment B3, the gauge wheel load sensor of Embodiment B2 has
the
pressure on the ram increased only in response to a change in the down force
on the gauge
wheel.
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According to Embodiment B4, the gauge wheel load sensor of Embodiment Bl
includes an accumulator coupled to the portion of the fluid-containing device
where the fluid
pressure increases in response to the movement of the of the mechanical
element.
According to Embodiment B5, the gauge wheel load sensor of Embodiment B4 has
the
mechanical element being a ram in a hydraulic cylinder containing pressurized
fluid, the ram
is coupled to the gauge wheel so that the ram is moved within the cylinder in
response to
vertical movement of the gauge wheel, and which includes an accumulator
coupled to the
hydraulic cylinder for receiving a portion of the pressurized fluid.
According to Embodiment B6, the gauge wheel load sensor of Embodiment B5 has
the
accumulator including a ram in a cavity that receives the pressurized fluid.
According to Embodiment B7, the gauge wheel load sensor of Embodiment B5 has
the
accumulator damp changes in the pressure of the fluid in response to vibratory
movement of
the ram.
According to Embodiment B8, a gauge wheel load sensor for an agricultural
planter
having a row unit that includes a pivotably mounted gauge wheel and a down
pressure
controller for controlling the down pressure on at least a portion of the row
unit, the load
sensor comprising: a mechanical element mounted for movement in response to
the
downward force applied to the row unit; a fluid-containing device containing
an element
coupled to the mechanical element for changing the fluid pressure in the fluid-
containing
device in response to the movement of the mechanical element; a transducer
coupled to the
fluid-containing device for producing an output signal in response to changes
in the fluid
pressure; and an energy storage device coupled to the fluid-containing device
for receiving a
limited amount of fluid in response to changes in the fluid pressure to damp
pressure spikes
in the output signal of the transducer.
According to Embodiment B9, the gauge wheel load sensor of Embodiment B8, the
fluid-containing device being a hydraulic cylinder, and the movable element is
a piston in the
cylinder.
According to Embodiment B10, the gauge wheel load sensor of Embodiment B8, the
energy storage device being an accumulator receiving pressurized fluid from
the fluid-
containing device, the accumulator containing a movable element responsive to
the pressure
of the fluid received from the fluid-containing device.
According to Embodiment B11, an agricultural planter row unit comprising a
pivotably
mounted gauge wheel and a down pressure controller for controlling the
elevation of the row
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Attorney Ref: 1 057P067CAO I
unit; a pair of gauge wheel support arms mounted for pivoting movement
independently of
each other; a gauge wheel equalizer arm extending transversely across the
support arms and
mounted for pivoting movement about an axis extending in the direction of
travel of the row
unit; and a pair of contact rollers mounted on opposite ends of the equalizer
arm, each of the
contact rollers engaging different ones of the support arms for pivoting the
equalizer arm in
response to the independent vertical movements of the support arms.
According to Embodiment B12, the agricultural planter row unit of Embodiment
B11,
including a rocker arm coupled to the center of the equalizer arm and mounted
for pivoting
movement in response to changes in the elevation of the center of the
equalizer arm.
According to Embodiment B13, a control system for controlling the down
pressure
applied to a soil-engaging component of an agricultural implement, the system
comprising: a
source of pressurized fluid; a down pressure actuator coupled to the soil-
engaging component
and to the source of pressurized fluid; an energy storage device and a piston-
containing
cylinder coupled to each other by a system containing pressurized fluid; a
check valve
coupled between the energy storage device and the down pressure actuator to
control the flow
of the pressurized fluid from the energy storage device to the cylinder; a
controllable relief
valve and a controllable variable orifice coupled between the down pressure
actuator and the
energy storage device to control the flow of the pressurized fluid from the
cylinder to the
energy storage device; a pressure sensor coupled to the pressurized fluid and
producing an
output signal corresponding to the pressure of the pressurized fluid; and a
controller coupled
to the pressure sensor to receive the output signal and configured to supply
control signals to
the controllable relief valve and the controllable variable orifice to control
the flow of the
pressurized fluid from the cylinder to the energy storage device based on the
pressure of the
pressurized fluid.
According to Embodiment B14, the control system of Embodiment B13, in which
the
energy storage device is an accumulator.
According to Embodiment B15, the control system of Embodiment B13 in which the
controller supplies a control signal to the relief valve to open the relief
valve in response to a
predetermined change in the pressure of the pressurized fluid.
According to Embodiment B16, the control system of Embodiment B13 in which the
controller supplies a control signal to the variable orifice to control the
size of the orifice
when the relief valve is open, to control the rate of flow of pressurized
fluid from the energy
storage device to the cylinder.
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While particular embodiments and applications of the present invention have
been
illustrated and described, it is to be understood that the invention is not
limited to the precise
construction and compositions disclosed herein and that various modifications,
changes, and
variations can be apparent from the foregoing descriptions without departing
from the spirit
and scope of the invention as defined in the appended claims.
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