Note: Descriptions are shown in the official language in which they were submitted.
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FIELD MARKER DISC WITH ADJUSTABLE OPERATING ANGLE
This invention is in the field of agricultural implements and in particular
disc markers to
operative to mark a driving guide in the soil for implement operation.
BACKGROUND
Field markers are used in many farm operations, including seeding, tillage,
chemical
application, and fertilizer application. Field markers generally include a
disc on the end
of an arm to make a visible mark on the ground laterally offset from the
implement to
give the driver a visible guide for spacing the implement on the next pass.
Such disc markers are disclosed for example in United States Patent Numbers
6,125,944
and 5,785,128 to Redekop, 5,542,190 to Wahls, 5,425,427 to Haugen, and
5,027,525 to
Haukaas. Breakaways using shear pins, bolts, trips or the like are desirable
to allow the
marker to move back when it contacts an obstacle, thus avoiding or at least
reducing
damage from the contact. When the breakaway acts, it is generally required to
stop
operations and reset the marker in the operating position. Particular
breakaways for field
markers are disclosed in United States Patent Numbers 5,957,216 to Redekop,
4,825,957
to White et al., and 6,263,976 and 6,334,492 to Hundeby.
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The patents of Hundeby also disclose a slotted mounting plate for the disc
that facilitates
adjusting the disc from a more aggressive to a less aggressive angle relative
to the
operating travel direction. This angle is adjusted so that the proper mark is
made in the
soil as soil conditions vary from field to field. When the soil is hard, and
the angle of the
disc with respect to the direction of travel is too small, the disc will not
bite into the soil,
instead riding on top and making only a slight mark that is difficult to see
and follow.
The disc will also ride out of the ground and fail to make a satisfactory mark
when trash
covering the ground is excessive.
To overcome this problem, the disc angle is adjusted to a more aggressive
larger angle to
the travel direction, where it will bite into the soil better, and penetrate
trash better, and
thus make a satisfactorily visible mark. On the other hand, when the soil is
relatively
soft, and the disc angle is too large, the disc will bite in too much and plow
an
undesirable trench. Also such plowing causes excessive strain on the marker
arm which
can damage the arm, and can in some cases trip breakaways.
The manual disc angle adjustment in the prior art markers of Hundeby and
others does
not address the common situation where soil conditions vary within a single
field. The
disc angle must be set such that it makes a satisfactory mark in the hard
areas, and plows
a trench in the soft areas, or alternatively makes a mark that is difficult to
see in the hard
areas, and satisfactory in the soft areas.
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The fixed angle also causes the similar problems on curves and turns. The
effective
operating angle of the disc changes on curves and turns such that the angle
becomes less
aggressive when turning one direction, and more aggressive when turning the
other
direction.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide an apparatus for
automatically
adjusting the operating angle of a field marker disc to a suitable angle as
soil conditions
change. It is a further object of the present invention to provide such an
apparatus that
automatically adjusts the disc operating angle to a suitable angle when the
implement is
moving along a curved path.
It is a further object of the present invention to provide such an apparatus
wherein a bias
force is balanced against the force exerted on the disc by the soil to
maintain the disc at a
suitable operating angle as the force exerted on the disc by the soil varies.
In a first aspect the invention provides a field marker apparatus comprising a
marker arm
adapted for attachment at an inner end thereof to an agricultural implement
such that the
marker arm extends laterally from the implement as the implement moves in an
operating
travel direction, and an outer end of the marker arm is supported by a
rotatable disc
adapted to engage the ground to make a furrow substantially parallel to the
operating
_ . _~.____...
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travel direction. The disc is pivotally mounted to the apparatus such that an
operating
angle between the disc and the operating travel direction can pivot from a
most
aggressive operating angle to a least aggressive operating angle. A bias
element is
operative to exert a bias force on the disc that causes the disc to pivot
towards the most
aggressive operating angle.
In a second aspect the invention provides a disc apparatus adapted for
attachment to a
field marker having a marker arm adapted for attachment at an inner end
thereof to an
agricultural implement such that the marker arm extends laterally from the
implement as
the implement moves in an operating travel direction. The disc apparatus
comprises
mounting means to mount a disc rotatably to an outer end of the marker arm
such that the
outer end of the marker arm is supported by the disc, and such that the disc
engages the
ground to make a furrow substantially parallel to the operating travel
direction;. The
mounting means further comprises pivot means operative to allow the disc to
pivot about
a substantially upright pivot axis such that an operating angle between a
rotational plane
of the disc and the operating travel direction can vary from a most aggressive
operating
angle to a least aggressive operating angle. Bias means are operative to exert
a bias force
on the disc that causes the disc to pivot towards the most aggressive
operating angle.
The bias force moves the rotational plane of the disc away from the line of
travel
increasing the operating angle to a more aggressive angle such that the disc
bites into the
soil more. When the disc bites into the soil more, the drag force of the soil
on the disc
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increases. This drag force is exerted on the disc in a direction opposite to
the bias force
and causes the disc to pivot towards the least aggressive operating angle. If
the bias force
and any limits on pivotal movement of the disc were removed, the disc would
rotate in a
plane that was substantially parallel to the operating travel direction, with
an operating
angle of essentially zero, where the drag forces on the disc would be minimal
as the disc
would be rolling along the soil without moving any soil, or at most a minimal
amount of
soil.
When the bias force and the opposite drag force are equal, the disc does not
pivot any
further and the apparatus is in equilibrium. The apparatus is configured such
that the
equilibrium operating angle is that operating angle where the disc makes a
visible furrow
in typical soil and trash conditions without plowing a trench. The bias force
can be
adjustable so that by increasing or decreasing the bias force, the equilibrium
operating
angle can be varied to suit particular soil conditions and to create a more
pronounced or
less pronounced furrow.
When the disc of the apparatus of the invention encounters a soft field area
the disc bites
in more, increasing the drag force such that the drag force overcomes the bias
force and
pivots the disc towards a less aggressive operating angle until the drag force
experienced
by the disc again equals the bias force and a new less aggressive equilibrium
operating
angle is achieved. At this new equilibrium angle, the disc makes a
satisfactory mark in
the soft ground.
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Contrarily, when the disc encounters a harder field area, or heavy trash
cover, the disc
rides out of the ground and bites in less, reducing the drag force such that
the bias force
overcomes the drag force and pivots the disc towards a more aggressive
operating angle
such that the disc bites into the soil more and increases the drag force until
the drag force
experienced by the disc again equals the bias force and a new more aggressive
equilibrium operating angle is achieved. At this new equilibrium angle, the
disc makes a
satisfactory mark in the hard or trashy ground.
Thus the operating angle of the disc varies though a range from most to least
aggressive
operating angles as the implement carrying the marker moves along the field
encountering varying soil conditions. The disc may ride out or plow briefly,
but the bias
apparatus will quickly make the necessary adjustments to correct the operating
angle.
Conveniently the bias element can be a spring, and a shock absorber can be
added to
dampen the movement of the disc. Alternatively an active hydraulic cylinder
can be used
to exert a constant bias force on the disc.
DESCRIPTION OF THE DRAWINGS:
While the invention is claimed in the concluding portions hereof, preferred
embodiments
are provided in the accompanying detailed description which may be best
understood in
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conjunction with the accompanying diagrams where like parts in each of the
several
diagrams are labeled with like numbers, and where:
Fig. 1 is a top view of an embodiment of the invention;
Fig. 2 is a top view of the embodiment of Fig. 1 mounted on the outer end of
an
implement;
Fig. 3 is a top view of the embodiment of Fig. 1 wherein the disc is oriented
at the
least aggressive angle;
Fig. 4 is a top view of the embodiment of Fig. 1 wherein the disc is oriented
at the
most aggressive angle;
Fig. 5 is a top view of a hydraulic cylinder used as an alternate bias
element;
Fig. 6 is a top view of an alternate embodiment of the invention, showing an
alternate configuration of the disc, bias element, and pivot plate;
Fig. 7 is a top view of the embodiment of Fig. 6 showing the operating angle
in a
negative position with respect to the straight ahead operating travel
direction.
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DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS:
Figs. 1 and 2 illustrate a field marker apparatus 1 of the invention
comprising a marker
arm 3 adapted for attachment at an inner end 3A thereof to an agricultural
implement 5
such that the marker arm 3 extends laterally from the implement 5 as the
implement 5
moves in an operating travel direction T. The outer end 3B of the marker arm 3
is
supported by a rotatable disc 7 that bites into and engages the ground 9 to
make a furrow
11 substantially parallel to the operating travel direction. As seen in Fig.
2, the marker
arm 3 is pivotally attached to the implement 5 so it can move up and down to
follow the
ground 9. Typically such marker arms 3 also fold into a transport position.
The disc 7 is rotatably mounted via a shaft 10 and bearings 12 to a pivot
plate 13. The
pivot plate 13 is pivotally attached to the outer end 3B of the marker arm 3
by a pivot pin
such that the pivot plate can pivot about a generally upright pivot axis PA.
Thus the
15 disc 7 can pivot with respect to the arm 3 such that the operating angle N
between the
disc 7 and the operating travel direction T can change from a most aggressive
operating
angle MN to a least aggressive operating angle LN, as seen in Figs. 3 and 4.
The pivoting
movement of the pivot plate 13 with respect to the arm 3 is limited by a limit
pin 17 fixed
to the arm 3 that extends through an arctuate slot 19 in the pivot plate 13.
The length of
the slot 19 defines the most and least aggressive operating angles MN, LN,
with the limit
pin contacting the end of the slot 19 at both extremes as illustrated in Figs.
3 and 4.
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A bias element 20 is operative to exert an inward force F on the pivot plate
13. In the
embodiment of Fig. 1, 3, and 4 the pivot plate 13 extends forward and rearward
from a
pivot axis PA and the bias element 20 is attached at one end thereof to the
forward
portion of the pivot plate 13 via a cable 25 attached to one of a plurality of
holes 27 in the
forward portion of the pivot plate. The opposite end of the bias element 20 is
attached to
a mid-point of the marker arm 3. The disc 7 is rotatably mounted on the
rearward portion
of the pivot plate 13 and oriented such that the rotational axis RA of the
disc 7 extends
forward and outward from the disc 7.
With the configuration of the disc 7, pivot plate 13, and pivot axis PA, the
force F exerted
by the bias element 20 on the pivot plate 13 causes the disc 7 to experience a
bias force
BF that pulls the disc 7 forward towards the most aggressive operating angle
ML
illustrated in Fig. 4. The bias force BF exerted on the disc 7 can be adjusted
by attaching
the cable 25 to different holes 27 located nearer to or farther from the pivot
axis PA to
change the leverage exerted on the disc 7 by the bias element 20 exerting
force F.
The bias element 20 illustrated in Fig. 1 comprises a spring 22 and also a
shock absorber
24 to dampen the movement of the pivot plate 13. An alternate bias element is
illustrated in Fig. 5, being an extendable hydraulic cylinder 50 operatively
connected to
an active hydraulic sourcE supplying hydraulic fluid 52 at an operating
pressure such that
the hydraulic cylinder 50 extends and retracts, and hydraulic fluid 50 goes
into and out of
the hydraulic cylinder 50, in response to forces exerted thereon that are
greater or lesser
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than the force exerted by the operating pressure on the hydraulic cylinder 50.
The bias
element of Fig. 5 has the advantage that the force F is constant as the
operating angle N
varies and the hydraulic cylinder 50 extends and retracts, whereas the force F
will vary as
a spring extends and contracts.
Where a spring is used, the pivot axis PA and spring location could be
oriented on an arc
so that as the disc pivots the leverage changes to compensate for changes in
the force F as
spring length varies, thereby maintaining a relatively stable bias force BF on
the disc.
Maintaining the bias force BF stable is not required for the operation of the
apparatus, as
the drag force DF and bias force BF will balance out in any event, but
performance is
improved where variations in the bias force BF are minimized.
As seen in Fig. 2, the rotational axis RA of the disc 7 is oriented somewhat
downward
when in the operating position as is common with such marking discs. Fig. 1
shows how
the rotational axis RA and the rotational plane of the disc 7 are oriented
with respect to
the operating travel direction T when the arm is in a substantially horizontal
position, to
more simply show the operation of the apparatus.
Fig. 6 illustrates an alternate configuration of the apparatus wherein the
bias element
exerts an outward force F. The bias element is attached at a first end thereof
to the
rearward portion of the pivot plate 113 and at the opposite end thereof to a
mid-point of
the marker arm 103. The disc 107 is rotatably mounted on a forward portion of
the pivot
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plate 113 such that a rotational axis RA of the disc 107 extends forward and
outward
from the disc 107. The disc 107 is illustrated as a flat disc which is
sometimes used in
such markers instead of the concave disc illustrated in Figs. 1 - 4 to make
the furrow 111.
The bias force BF moves the rotational plane of the disc 7, 107 away from the
line of
travel increasing the operating angle N to a more aggressive operating angle N
such that
the disc bites into the soil more. When the disc bites into the soil more, the
drag force DF
of the soil on the disc increases. As illustrated, this drag force DF is
exerted on the disc
in a direction opposite to the bias force BF and causes the disc to pivot
towards the least
aggressive operating angle LN. Various alternate configurations could also be
used to
exert a bias force on the disc that would be counter-balanced by the drag
force of the soil
against the disc, and result in an operative apparatus. Compression or
extension springs
could be used, and an active hydraulic cylinder can be configured to exert a
force F in
either direction, as is known in the art.
When the bias force BF and the opposite drag force DF are equal, the disc 7,
107 does not
pivot any further and the apparatus is in equilibrium. When the disc 7, 107
encounters a
soft field area the disc bites in more, increasing the drag force DF such that
the drag force
DF overcomes the bias force BF and pivots the disc towards a less aggressive
operating
angle N until the drag force DF experienced by the disc again equals the bias
force BF
and a new less aggressive equilibrium operating angle N is achieved. At this
new
equilibrium angle N, the disc makes a satisfactory mark in the soft ground.
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Contrarily, when the disc 7, 107 encounters a harder field area, or heavy
trash cover, the
disc rides out of the ground and bites in less, reducing the drag force DF
such that the
bias force BF overcomes the drag force DF and pivots the disc towards a more
aggressive
operating angle N such that the disc bites into the soil more and increases
the drag force
DF until the drag force DF experienced by the disc again equals the bias force
BF and a
new more aggressive equilibrium operating angle N is achieved. At this new
equilibrium
angle, the disc makes a satisfactory mark in the hard or trashy ground.
In the same manner the operating angle N of the disc changes as the implement
follows a
curved path. When the embodiment of Fig. 1 is turned to the left, the
operating angle N
will decrease as the travel direction T indicated by the arrow moves to the
left, and the
disc action will become less aggressive. The drag force DF will decrease and
the bias
force BF will move the disc towards a more aggressive angle, maintaining a
suitable
operating angle F and disc action so that the furrow 11 remains visible.
Similarly when
turning to the right, the operating angle N will increase and the drag force
DF will
increase, overcoming the bias force BF to move the disc towards a less
aggressive
operating angle N, and thereby prevent plowing a trench.
In order to allow for proper action of the apparatus in pronounced turns, the
slot 119 can
be elongated such that the pivot plate 113 and disc 107 can move to position
wherein the
angle N is negative with respect to the straight forward operating travel
direction T.
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The apparatus of the invention thus continuously adjusts the angle N as the
drag force DF
of the soil on the disc varies, either from a change on soil conditions or a
curve.
The foregoing is considered as illustrative only of the principles of the
invention.
Further, since numerous changes and modifications will readily occur to those
skilled in
the art, it is not desired to limit the invention to the exact construction
and operation
shown and described, and accordingly, all such suitable changes or
modifications in
structure or operation which may be resorted to are intended to fall within
the scope of
the claimed invention.
