Note: Descriptions are shown in the official language in which they were submitted.
CA 02243220 1998-07-15
DELIYERY SYSTEM FOR THE ~ul~TIC DELI~E~Y
OF SEEDS TO A METERTNG ~
FIELD QF THE INVENTION
The subject matter of the invention relates
generally to farm implements. More particularly, it
relates to planters. More particularly it relates to
pneumatically seed delivery systems for planters.
BACKGROUND OF THE INVENTION
In recent years pneumatic delivery systems have been
employed in farm vehicles to deliver seed, fertilizer and
herbicides to planters and tool bars. One such system is
shown in U.S. Patent No. 4,473,016, issued to Gust. In
this system, a tractor pulls a particulate feeder or
"cart" typically having two or three separate hoppers.
The cart, depending upon its size, may have three or four
wheels and a longitudinal tube extending its length.
Each hopper is typically equipped with a rotating
metering cylinder disposed between that hopper and the
tube to meter particulate matter (seed, fertilizer or
herbicides) into the tube when the cylinder rotates. An
engine or hydraulic motor on the cart drives a fan that
is pneumatically coupled to the tube to blow air through
CA 02243220 1998-07-1~
the tube. The air flow in the tube accelerates the
particulate matter and blows it into a series of
pneumatic manifolds on the planter or tool bar (also
towed by the tractor) tha~ pneumatically distribute the
particulate matter equally to a plurality of ground
_ openers.
Seed and fertilizer may be distributed
simultaneously to the tool bar by placing seed in one
hopper and fertilizer in another, both of which are then
metered into the tube to be sent to the pneumatic
manifold distribution system on the planter. There are
several drawbacks to this method, however. First, sL~ce
the seed is mixed with the fertilizer in the tube, seed
may be burned by the fertilizer. To prevent this in
other embodiments, the tube has been subdivided into two
separate air paths by placing a partition or "ribbon~
down the length of the tube. The seed is then metered
into one-half of the tube, and the fertilizer is metered
into the other half of the tube. At the end of the tube,
each of these separate partitions is directed to a
separate pneumatic distribution system on the planter,
rather than distributing a seed-chemical mix in a single
common manifold system such as that shown in the Gust
reference.
Even a dual manifold and partition arrangement
has drawbacks, however. Using air in a manifold system
to evenly distribute the seeds may be acceptable f~r
durable seeds, such as wheat, but can cause problems for
seeds such as canola and corn. When a manifold
distribution system is used with these grains, they
suffer damage when they impact the top of the manifolds
and suddenly reverse direction to proceed down the tubes
extending radially away from the manifold. In addition,
the air flow in a manifold distribution system must be
high to lift the grains up the manifolds and to cause
CA 02243220 1998-07-1~
sufficiently random tur~ulence to distribute seeds evenly
to each of the rows. This commonly results in damage to
1-25% of the seeds.
There are additional disadvantages to a
manifold distribution system for crops that require very
_ low application rates. For example, canola, corn and
sunflower seeds are deposited at a rate of between 4 and
25 pounds of seed per acre. When a metering cylinder at
the bottom of a hopper is used to meter seed at this
rate, the flutes must be made especially small and
carefully tapered to insure that seed is introduced into
the longitudinal tube evenly over time. Also, the
manifold system is not able to distribute the seeds
evenly when only small amounts are being applied.
It is possible to accurately meter seed flow
with less damage by eliminating the manifold arrangement
for pneumatically distributing seeds and replacing it
with one or more mechanical metering systems such as the
Cyclo unit illustrated in U.S. Patent No. 4,519,525. In
such a system, the air velocity can be reduced since air
is used merely to deliver seed to the Cyclo unit and the
Cyclo unit mechanically distributes seeds to each row.
Providing two mechanical metering devices in series (the
rotating cylinder and Cyclo unit) has drawbacks, however
The two metering systems are difficult to synchronize.
Since one feeds the other, a lack of synchronization can
overfill or underfill the Cyclo unit, potentially
plugging it, or starving it for seeds, respectively. To
prevent this problem, some method of controlling the
metering rate to the Cyclo unit must be provided.
Experiments have been conducted in which a sensor on the
Cyclo drum signals the metering cylinder on the cart to
turn on and off. Such methods, however, require the
addition of a motor or other controllable apparatus to
CA 02243220 1998-07-15
rotate the metering cylinder, and also a sensor at each
Cyclo unit to sense its level of seed.
What the Applicants propose is a new apparatus
for supplying grain from a portable grain bin to a grain
meter that will reduce or eliminate the above
disadvantages.
-
SUMMARY OF THE PRESENT INVE~TION
According to a first em~odiment of theinven~ion, an apparatus for regulating the level of seed
in a seed m-ter is claimed including a tubular member
having a first membrane defining an upper surface of a
lower end of the tubular member, and a baffle disposed in
the tubular member to block a portion of the inner cross-
sectional area of the tubular member. The tube may have
a rectangular or square cross-section with a cross-
sectional area of between l and 16 square inches, or more
preferably between 3.06 and 7.56 square inches. the
baffle may block 20% to 50% of the cross-sectional area
of the tube, and the lower end of the tube may be
substantially parallel to the inner surface of a seed
meter, defining a gap of between 0.5 and 1.0 inches
therebetween. The tube may define an angle of between 15
and 35 degrees with respect to the inner surface of the
seed meter. The seed meter may be a Cyclo unit. The
membrane may extend to the end of the tube to at least
partially define a lower end of the tube. The tube may
be connected to a flexible hose that in turn is connected
to a seed distribution tube oriented above a layer of
grain. The hose may have an area at least 15% smaller
than the area of the seed distribution tube. The hose
may be inserted into the seed distribution tube to within
2 and 8 inches of the end of the tube.
Other principal features and advantages of the
invention will become apparent to those skilled in the
.,. . ~, , . , , ,. ~ .. . .. .
CA 02243220 1998-07-15
art upon review of the following drawings, the detailed
description and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure L illustrates a cart in accordance with
the present invention;
~ Figure 2 illustrates a side view of the Figure
1 cart,
Figure 3 illustrates a detail view of the
Figure 1 cart;
Figure ~ illustrates a cross-sectional view of
the Figure 1 cart taken at Section 4-4 in Figure 3;
Figure 5 illustrates a detail view of the
Figure 1 cart showing a portion of the Figure 1 cart
undercarriage;
Figure 6 illustrates a cross-sectional view of
the housing of the Figure 1 cart taken at Section 6-6 in
Figure 8;
Figure 7 illustrates a side detail view of the
cart of Figure 1 showing an alternate drive system for
the metering cylinders;
Figure 8 illustrates a vertical cross-section
of the housing and tube taken at Section 8-8 in Figure 6;
Figure 9 illustrates an alternative pneumatic
insert for the housing;
Figure 10 illustrates a cross-sectional view of
the housing in tube with the insert of Figure 9
installed;
Figure 11 illustrates a cross-sectional view of
the insert of Figure 9 taken at Section 11-11 in Figure
10;
Figure 12 illustrates a schematic
representation of a Cyclo unit;
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--6--
Figure 13 illustrates a cross-sectional ~iew of
the Cyclo unit of Figure 12 taken at Section 13-13 in
Figure 12;
Fi~ure ~4 illustrates a cross-sectional view of
the seed tube of Figure 13 taken at Section 14-14; and
_ Figure 15 illustrates a cross-sectional view of
~ the seed tube of Figure 13 taken at Section 15-15.
Before explaining at least one embodiment of
the invention in detail it is to be understood that the
invention is not limited in its application to the
details of construction and the arrangement of the
components set forth in the following description or
illustrated in the drawings. The invention is capa~le of
other embodiments or being practiced or carried out in
various ways. Also, it is to be understood that the
phraseology and terminology employed herein is for the
purpose of description and should not be regarded as
limiting.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figure 1, a particulate feeder 10
(or "cart" as it is commonly referred to) is disclosed
supported by a main frame 12, with a plurality of ground
engaging wheels 14 rotatably mounted on frame 12 to
movably support the main frame 12 and particulate feeder
10 on the ground. Each wheel 14 is suitably supported on
an axle 16 via suitable bearing means (not shown). Axles
16 are mounted on laterally extending members 18 and 20
of main frame 12 and aligned so that the wheels 14 track
substantially parallel paths in operation. Laterally
extending member 18 comprises a portion of main frame 12
proximate to a forward end 22 of particulate feeder 10
and laterally extending member 20 comprises a portion of
main frame 12 proximate to a rearward end 24 of
particulate feeder 10. In this description, "forward"
CA 02243220 1998-07-1~
--7--
and "rearward" are used to describe the relative
components as viewed from right to left as in Figures 1
and 2. It is understood that particulate feeder 10 could
be operably hitched behind a tractor at either its
~ forward or rearward ends so that the use of these
- directional terms in this description is merely for
discussion purposes.
A rigid elongated tube 26 extends
longitudinally as the primary longitudinal portion of the
main frame 12. Tu~e 26 extends from forward end 22 to
rearward end 24 of particulate feeder 10 with the
laterally extending members 18 and 20 fixedly mounted
perpendicularly thereto.
As shown in Figure 2, particulate container bin
28 is supported on main frame 12 by forward and rearward
support buttresses 30 and 32. Forward support buttress
30 is fixedly secured to the forward end of tube 26 and
rearward support buttress 32 is fixedly secured to
laterally extending member 20. Particulate container bin
28 can be divided into a plurality of hoppers by
positioning a divider means such as a divider wall 34
within container bin 28. Bin 28 is thus divided in this
embodiment into a forward hopper 36 an rearward hopper
40. Each hopper is generally rectangular with an access
door 42 at its upper end and sloped walls forming its
lower end to form a rectangular funnel arrangement
leading to a particulate discharge outlet 44.
As shown in Figures 2-4, a sliding door 46 is
mounted adjacent discharge outlet 44 to selectively open
and close outlet 44 to the passage of particulate matter.
Each sliding door 46 is provided with means for moving
the sliding door relative to the particulate outlet 44 so
that the position of door 46 is selectively variable from
a first open position to a second closed position to
control the size of the particulate outlet 44.
CA 02243220 1998-07-15
Preferably, the moving means comprises a rack-and-pinion
arrangement where rack ~0 is mounted on bin 28 and a
pinion 52 is rotatably mounted in a sleeve 54 sec~red to
each door 46. The teeth of pinion 52 are aligned with
the teeth of rack 50 so that rotation of the pinion 52 on
its shaft moves the door 46 relative to outlet 44. A
~ crank 56 may be attached to pinion 52 to rotate the
pinion. Door 46 is dimensioned to seal outlet 44 when in
its closed position to prevent particulate matter from
passing through outlet 44.
A housing 60 ex~ends from outlet 44 of each
hopper to elongated tube 26. The housing is generally
rectangular in horizontal cross-section and corresponds
to the rectangular opening defined by outlet 44. As
shown in Figures 3, 4 and 6, housing 60 has longitudinal
side walls 62 and ~4 and transverse end walls 66 and 68.
The enclosure formed by housing 60 is subdivided into
first and second ch~h~rs 70 and 72, respectively, by a
generally vertical wall 74. Forward hopper 36 and
rearward hopper 40 each has its own housing 60.
Each housing can be alternately fitted with two
structures for delivering particulate matter. The first
of these, a particulate metering cylinder, is described
in detail in the Gust reference. This metering cylinder
is shown in Figures 3 and 6 of the present application.
The other structure is a plenum for the pneumatic
delivery of seed preferably to one or more mechanical
metering devices located on the planter or tool bar.
This structure will be discussed below in regard to
Figures 9-11. Metering cylinder 76 is rotatably mounted
on a longitudinal axis in the first c~mh~r 70 in housing
60. Cylinder 76 has a first end 78 and a second end 80
defining its longitudinal axis of rotation. A plurality
of ribs 82 extend from the first end to the second end on
its outer cylindrical surface to define a plurality of
CA 02243220 1998-07-15
troughs 84 on the outer side of cylinder 76 therebetween.
A drive shaft 86 is rotatably supported by bearing
collars o8 adjacent to each end of housing 60. Each
bearing collar ~8 is secured to its respective end wall
66, 68 of housing 60 by a bearing mount plate 90 and
_ fasteners 92. Drive shaft 86 passes through the metering
~ cylinder 76 from its first end 78 to its second end 80
and passes completely through housing 60 longitudinally
(both chambers 70 and 72) as shown in Figure 6.
Preferably, the drive shaft is comprised of a plurality
of drive shaft sections 94. Shaft sections 94 are
secured end-to-end along a single axis of rotation, as
best shown in Figures 2 and 6, by suitable fastening
means, such as a plurality of connecting collars 96. In
this manner, a metering cylinder can be removed or
replaced from either housing 60 without requiring the
removal of the entire drive shaft 86 from both housings.
The metering cylinder 76 is slidably mounted on drive
shaft 86 to rotate with drive shaft 86 when it is
rotated. In one embodiment, the drive shaft is driven by
one of the wheels of the particulate feeder to thereby
deliver a predetermined amount of particulate to a
specific area of soil regardless of the velocity of the
particulate feeder. As shown in Figures 2 and 5, a drive
gear 98 engages a chain 100 which engages a sprocket 102
axially secured to one of the wheels 14. Drive gear 98
is, in turn coupled to drive rod 104 which is coupled to
a right-angle gear box 106, which in turn is coupled to
drive shaft 86. Thus, the rotation of drive shaft 86 is
proportional to the rotation of wheel 14. Alternatively,
a hydraulic or electric motor can be used in place of the
gear train of Figures 2 and 5, as shown schematically in
Figure 7. In this alternative embodiment, a hydraulic or
electric motor 108 is fixedly mounted to elongate tube
26. A sprocket 110 is coupled to motor shaft 112 which
CA 02243220 1998-07-1~
--10--
in turn is coupled through an endless chain 114 to gear
box 106. A proportional control valve or electric
controller 116 is coupled -o motor 108 by hydraulic
tubing or electrical wire ' 18 to regulate the flow of
hydraulic fluid or voltage to motor 108. An electronic
controller 120 is electrlcally coupled to proportional
valve or electric controller 116 to determine the degree
of valve opening or voltage output, and thus the
rotational speed of motor 108 and drive shaft 86. This
controller may be coupled to other devices, such as a
velocity sensor 11~ to sense the speed of the vehicle
over the ground, or to navigational devices such as a ~PS
navigation system 121. In this manner, the rate of
application of particulate matter may be regulated
depending not only on the rotation of the vehicle's
tires, but on its actual position or speed in the field.
Figure 8 shows the configuration in lateral
cross-section) of the first chamber 70 of housing 60.
Metering cylinder 76 is mounted under sliding door 46 and
rotates on drive shaft 86 in a clockwise direction when
drive shaft 86 is driven. A particulate shield 126 is
mounted adjacent to an upper edge of longitudinal side
wall 62 of housing 60 and extends the full longitudinal
length of the first chamber 70. Particulate shield 126
covers a limited arcuate range of the outer side of
metering cylinder 76 sufficient to prevent particulate
flow between cylinder 76 and shield 126 when cylinder 76
is rotating in use. Shield 126 prevents particulate
matter from flowing downwardly between against the
rotation of cylinder 76 and guides particulate matter
into the troughs 84 of cylinder 76.
Side wall 64 of housing 60 has a panel 128 that
extends the entire longitudinal distance of side wall 64.
Panel 128 is removably connected to side wall 64,
preferably with a quick release means such as wing nuts
... ,. . ,~ , . , . . ,. , . ., .~ ~ ,.. .. .. .
CA 02243220 1998-07-15
130 or 'atches. Seal 132 is preferably provided between
the side wall and the panel to prevent the leakage of
particulate matter, and to maintain the air pressure
within the elongated tube 26 coupled to the bottom of
housing 60. Preferred materials include a cork, plastic
or rubber gasket, slightly flexible to conform with the
mating surfaces of side wall 64 and panel 128.
A curved particulate guide 134 is fixed to he
inner facing surface of panel 128. Guide 134 prevents
particulate matter from pouring freely from outlet 44,
past cylinder 76 and into the bottom of housing 60. By
fitting in close proximity to cylinder 76, it regu~ates
the amount of particulate swept by the rotating cylinder
into the bottom of housing 60.
In addition to working in conjunction with the
guide to regulate flow through the system, the removable
panel also provides access to cylinder 76 for
maintenance, adjustment or replacement.
In operation, seed enters troughs 84 under the
force of gravity. As the mechanical, hydraulic or
electric drive systems described above rotate the
metering cylinder the troughs are rotated past guide 134
until the end of guide 134 is reached. At this point,
the seed falls through an upper opening in tube 26. Tube
26 is not just a structural member, but is a part of the
seed distribution system itself. Referrinq to Figure 2,
a fan 136 driven by engine 138 forces air into tube 26.
This air flows through the length of tube 26 until it
exits in flexible hose 140 coupled to the end of tube 26
remote from the fan and motor. As seed is metered by
cylinder 76 into tube 26, this air flow is large enough
to carry the particulate matter with it as it travels the
length of tube 26, and upward, out of the system through
flexible hose 140. As mentioned above, tube 26 may be
divided by a partition into two separate air paths. In
CA 02243220 1998-07-15
--12--
such an arrangement the hoppers would empty into separate
air paths, and t-~o separate flexible hoses would lead
bac~ to the tool har, one from each of the air paths.
The above described metering cylinder is
capable of metering relatively large flow rates (on the
order of 300 pounds per minute at a fairly constant flow
rate. This works well for such materials as fertilizer,
herbicides, and seeds that are planted at a relatively
high rate (greater than 60 pounds per acre). It is not
as effective for seed such as canola, corn or sunflowers
which must be metered out at a rate of around 4-25 pounds
per acre.
A pneumatic delivery system 142 which may be
substituted for the removable panel and metering cylinder
of the device described above is shown in Figures 9-11.
Referring to Figure 9, pneumatic delivery system 142 is
comprised generally of a plenum 144 covered with one or
more gas-permeable membranes 146, with one or more open-
ended seed distribution tubes 148 disposed above the
membranes. Air blown up through the plenum travels
through the membrane and around the base o~ the open-
ended tubes. This air escapes upward through the open-
ended tubes carrying with it any grain which has spilled
between the open ends of the tubes and the membrane. A
portion of plenum 144 and membranes 146 are inserted into
either one or both of the housings 60 in place of
removable panel 128 and cylinder 76 so that seed or other
particulate matter in the hopper will fall through outlet
44, onto the membranes and between the end of the
distribution tubes and the membrane.
Referring to Figures 9 and 10, plenum 144 is in
the form of a substantially square chamber 150 extending
the length of opening lS2 that panel 128 normally covers
when the metering cylinder is employed to meter
particulate matter, and an air conduit lS4 in fluid
CA 02243220 1998-07-1~
communlcatlon with square chamber lS0 that extends into
the houslng.
Square chamber 50 is formed of a vertical end
wall 156 that is joined to an inner vertical side wall
158 and an outer vertical side wall 160. A second
vertical end wall 162 is provided to which tube 164 is
coupled. Tube 164 is typically connected to an external
air supply via a flexible hose 215. In this manner air
may be forced through flexible hose 215 through tube 164
and into the plenum. Inner vertical side wall 158 of
chamber 150 has three openings 166 to direct air from
square chamber 150 into air conduit 154.
Referring to Figures 9 and 11, air conduit 154
is rectangular in vertical cross-section, with one end
fluidly coupled to square chamber 150 and a second end
abutting and substantially sealed by side wall 62 of
housing 60. Referring to Figure 10, the lower surface
172 of air conduit 154 seals off air flow into or from
tube 26, by sealing off opening 174 in tube 26. The
upper surface 176 of conduit 142 has openings 178 that
fluidly couple air conduit 142 to the upper portion of
housing 60. Openings 178 are covered with a
semipermeable membrane 146, such as a screen, a mesh, a
grid, a plurality of closely spaced or woven rods, or the
like, that will block the flow of particulate matter
downward into conduit 154, while permitting the flow of
air upward from air conduit 154 through membrane 146 and
out through tubes 148.
Referring to Figures 9 and 11, air conduit 154
also includes a first end wall 182 and a second end wall
184. T~ese walls are coupled to upper conduit surface
176 and lower conduit surface 172, and to inner vertical
side wall 158 of square chamber 150 to define the air
conduit. In addition, first end wall 182 has an upper
portion 186, and second end wall 184 has an upper portion
CA 02243220 1998-07-1~
188 that seal off the openlngs ln end walls 66 and 68 of
housing 60. The openings are created when shaft 86 is
removed, along with cylinder 76 to make room for air
conduit 142 of plenum 144 to be inserted into the housing
through opening 152. By sealing off these openings only
a limited amount of air can escape from the housing.
Coupled to and disposed between upper portion
186 of first end wall 182 and upper portion 188 of second
end wall 184 is seed deflection plate 190. This plate
extends at an angle of about 40 degrees of horizontal
from the upper portion of inner vertical wall 158 of
square chamber 150 into the housing. Plate 190 is
adjustably coupled to upper portions 186 and 188 to allow
the user to vary gap 192 between edqe 194 of plate 190
and side wall 62 of the housing. Since plate 190 is
disposed above membrane 146, between membrane 146 and the
hopper, it controls the flow of particulate matter onto
membrane 146. Gap 192 prefera~ly has a width of between
1 and 3 inches, depending on the type of seed and seed
flow rate.
A flange 196 is provided between square chamber
150 and air conduit 142 to engage the outer periphery of
opening 152 in the housing. A flexible seal 198 is
preferably disposed between flange 196 and the periphery
of opening 152 to prevent air and particulate matter from
escaping from the housing through opening 152.
The upper portion of vertical side wall 158 has
three additional openings, each defined by circular pipes
202, and each of which slidingly supports a seed
distribution tube 148. The outside diameter of each of
seed distribution tubes 148 is preferably only slightly
smaller than the inside diameter of pipes 202 in which
they are mounted. Each of pipes 202 preferably has a set
screw 204 or other clamping device for fixing its
respective seed distribution tube in a plurality of
CA 02243220 l998-07-l~
--15--
positions. In this manner, each cf the distribution
tubes' position with respect to ehe housing and membrane
can be separately ~djusted.
Each seed distribution tube 148 has a first end
extending through ~ertical side wall 158 and terminates
- adjacent to membrane 146. The distance between the
bottom edge of the tubes and the top of membrane 146 is
preferably adjusta~le over a range of between 0 and 2
inches. Seed distribution tubes 148 are oriented at an
angle of about 40 deqrees of horizontal, and preferably
at about the same angle as seed deflection plate 190.
The lower end 206 of the seed distribution tubes is cut
away such that the open end has a first edge 208 that
defines a plane substantially parallel to membrane 146.
Since, in the preferred embodiment, each tube's angle is
about 40 degrees from horizontal, and since the membrane
is substantially horizontal, the angle of edge 208 is
about 40 degrees with respect to the longitudinal axis of
tube 148. The effect is to provide a relatively constant
opening between the membrane and the open end of the seed
distribution tube along this edge. A second edge 210 is
provided at the end of the seed distribution tube that
defines a plane substantially perpendicular to the
longitudinal axis of the seed distribution tube. This
edge provides an increased gap between the end of the
distribution tube and the membrane in the form of an
arched opening 212 best seen in Figure Z. By providing a
larger gap at the edge of the seed distribution tube
closest to the source of particulate matter (i.e. the gap
between seed deflection plate l90 and side wall 62 of the
housing), the particulate matter can more easily spill
into the gap and be carried upward.
In use, the air conduit of the plenum is
inserted horizontally into opening 152 of housing 60
until upper and lower surfaces 176 and 172 are proximate
CA 02243220 l998-07-l~
--16--
to side wall 62 of housing 60. At this point seal 198 is
also proximate ~o opening 1~2 in side wall 64 cf housing
60. A quick release mechanism, here shown as latches 214
(Figure 9), are then engaged to compress seal 198 between
flange 196 and the periphery of opening 152. An air
- supply hose 215 is coupled to tube 164 to provide a
source of air under pressure to the plenum. The other
end of this hose is preferably coupled to fan 136. A
flexible hose is coupled to each distribution tube and
leads to the planter or tool bar.
When air is forced into the plenum through tube
164, it travels upward through membrane 146 into the
hopper. Once the hopper is pressurized, the only escape
for air is up the distribution tubes 148. Typically the
air supply maintains a positive pressure of between 12
and 22 ounces per square inch in the hopper.
Once door 46 is opened, grain falls down on top
of seed deflection plate 190 and then into gap 192
between seed deflection plate 190 and side wall 62 of
housing 60. After it passes through gap 192, it pours
onto membrane 146, increasing in depth until a portion of
the expanding pile of grain spills into the space between
the end of seed distribution tube 148 and membrane 146.
Since air is permitted to escape up the seed distrlbution
tubes, and does escape at considerable velocity, the air
flow has th¢ velocity necessary to levitate the grain up
the distribution tube, down the flexible hoses attached
to the tubes, and into the planter tool bar attached to
the remote end of the flexible hoses.
In some cases, each seed distribution tube will
feed a different number of metering devices on an
implemenc, and thus will have to supply different amounts
of grain. For this reason, each of the seed distribution
tubes can be separately adjusted to vary the gap between
that tube and its associated membrane. By widening the
CA 02243220 1998-07-1~
gap, the distance between the bottom end of distribution
tube 148 and the qrain increases, making it more
difficult to levitate the grain, which decreases the
amount of grain delivered with the same amount of air
flow.
- In a preferred installation, the hopper
illustrated in Figure 1 would be coupled to a planter or
tool bar and a tractor. In one of the housings, the
cylinder 76 would be replaced with pneumatic delivery
system 142 to distribute seed contained in one bin of the
hopper. Each seed distribution tube exiting that plenum
would be coupled to a mechanical metering system on the
planter, preferably one or more Cyclo units. The other
housing would support cylinder 76, which would meter
fertilizer from the other bin into tube 26. Tube 26, in
turn would be coupled to air distribution manifolds on
the planter or tool bar for distributing fertilizer to
each row that is planted. Thus, two distinct
distribution systems having substantially different
capacities to separately feed both seed and fertilizer
are provided in a single vehicle.
Pneumatic delivery system 142 in conjunction
with its associated hopper and housing provides a seed
delivery system whose seed output can be quite
effectively and automatically regulated by controlling
the amount of air that is allowed to flow up the
distribution tubes.
Figure 12 illustrates a mechanical metering
system, in this embodiment, a Cyclo unit that meters seed
to a plurality of ground openers or other seed insertion
devices. The Cyclo unit generally comprises a
cylindrical drum 216 that rotates about a substantially
horizontal axis. The drum is supported by, and is
rotationally sealed against a base plate 218.
CA 02243220 1998-07-1~
--18--
The drum has a plurallty of lndentatlons 220,
each having a hole 224 at its base through which air may
escape from the drum to the atmosphere. A fan (not
shown) supplies air into the interior of the Cyclo drum,
and maintains it at a pressure preferably about 5 to 15
- ounces per square lnch above atmospheric pressure. Air
escapes to the atmosphere from the drum through each of
the holes 224 in the drum indentations.
Grain is maintained at a relatively constant
level in the base of the Cyclo drum, tumbling in the
bottom of the drum as the drum rotates. As the seed
tumbles, and assuming it is maintained at the proper
depth in the drum, a single seed will fall into each and
every indentation. Due to the flow of air out holes 224
at the ~ottom of the indentation, each seed will become
trapped there. As the drum continues to rotate, each of
these seeds will be lifted to the uppermost point in the
drum, where upon it will begin to descend.
To release each row of seeds from their
respective indentations, a row of flexible polymeric
wheels 226, are disposed on an axle 228 and are pressed
against the outside of the drum. As the drum rotates,
these wheels roll across the outer surface of the drum.
During this rotation, the wheels will periodically cover
and seal off a row of holes 224. The effect is to
simultaneously release an entire row of seed.
As each row is released, each seed falls into a
manifold 230 comprised of 8 individual passageways. Each
of the passageways comprising the manifold are coupled to
flexible tubes (not shown), which lead to a ground opener
attached to the planter or tool bar. The manifold is
fixed to the base plate, which holds a free end 232 of
the manifold in close proximity to the rotating drum.
Referring to Figures 13 and 14, seed is
~5 delivered to the Cyclo unit through flexible hose 200
CA 02243220 1998-07-15
~ --19--
which is coupled to seed delivery .ube 234. Seed
delivery tube 234 is directed downward toward the bottom
of Cyclo drum 216 at an angle of between 15 and 35
degrees. Seed tube 234 is preferably rectangular in
axial cross-section, measuring between 1 and 4 inches
- square, and more preferably between 1.75 and 2.75 inches
~ square. It has a top surface 236, a bottom surface 238
and two vertical side walls 240. About 5 inches of the
seed tube extends into the Cyclo drum, terminating in an
open end 242 the edge of which defines a horizontal plane
parallel to, and equidistantly spaced from, t~e ~ottom of
the Cyclo drum. The gap between open end 24Z and the
bottom of the Cyclo drum is preferably between 0.5 and
1.0 inches, a wider gap being suitable for operation in
adverse conditions, such as side hills.
Referring to Figures 13 and 15, a gas-permeable
membrane 244, preferably in the form of a screen, mesh,
or grid, defines the top surface and upper half of each
side wall for the lower 4 to 5 inches of tube 234. This
zo screen preferably extends to open end 242.
When the system is initially started up, fan
136 blows air into the plenum, up through membrane 146
and distribution tube 148, through flexible hose 200
coupling the distribution tube to seed tube 234 and out
open end 242 into Cyclo drum. If the interior of seed
tube 234 had a constant open cross-sectional area over
its entire length, the individual seeds would arrive at
open end 242 with considerable velocity, which would
propel them completely out of open end 242 and into Cyclo
drum 216. The Cyclo drum would be substantially filled
at a high rate which might result in overfilling. To
reduce seed exit velocity during start up, a baffle 246
is provided inside seed tube 234 to block off between 20%
and 50% of the cross-sectional area of the seed tube.
This baffle is preferably disposed upstream of membrane
CA 02243220 1998-07-1~
- 20 -
244. Baffle 246 is preferably disposed across the bottom
surface 238 cf seed tube 234 thereby providing a gap
between the top surface 236 of seed tube 234 and the top
of baffle 246 for air and seed to escape. Air with
entrained seed enters the seed tube on start-up with a
- considerable velocity. However, since seed tube 234 is
~ preferably straight, the seed will fall downward under
the force of gravity as it travels down the seed tube
approaching the baffle. This effectively separates the
seed from the air propelling it and may be considered to
divide the seed tube into two different flow areas: an
upper region containing primarily air, and a lower region
containing primarily seed. For this reason, the seed,
traveling in the lower portion of the seed tube impinges
upon baffle 246 while the air proceeds, relatively
unimpeded, through the gap defined between the top of
baffle 246 and top surface 236 of the seed tube. As the
seeds impinge upon baffle 246, they bounce off the
baffle, reversing their direction of travel and go back
upstream, whereupon they collide with seeds traveling
downstream to collectively create a turbulent, relatively
low-velocity, seed-filled region just upstream of baffle
246. As might be expected with this turbulent activity,
all the seeds will eventually get blown over the top of
baffle 246 and will continue down seed tube 234 at a
considerably reduced velocity. This reduction in overall
velocity insures that the start-up seed flow is not
prematurely ejected from the end of seed tube 234 into
the Cyclo drum, but gradually fills the lower end of the
seed tube at a lower overall velocity.
Air escapes from seed tube 234 predominately
through membrane 244, and not through open end 242 of
seed tube 234 during a normal operation. Since this air
flow carries the grain up the flexible tube coupling
distribution tube 148 and seed tube 234, seed flow may be
. ,, ; . ~ . ,,~ ,,,, .. . . ., ,. . ., ., . ., . , .,i .. .... .. , . ,, .. ". . .. .
CA 02243220 1998-07-1~
reduced by restricting air flow. Air flow, and thus the
seed puddle in the bottom of the Cyclo drum is controlled
in the following manner. ~hen seed ls carried down the
seed tube, it rests on the bottom of Cyclo drum 216. If
the turninq Cyclo drum does not remove seed faster than
- it arrives from the distribution tube, the seed begins to
fill the lower screened-in portion of the seed tube. As
the lower screened-in portion is filled, membrane 244 is
increasingly blocked, gradually preventing the free flow
of air out through membrane 244. As this air flow is
gradually reduced, the flow of seed is also gradually
reduced, since the velocity of air up through the
distribution tube (and hence its ability to lift seed) is
reduced. Eventually, the air flow is reduced to the
point that grain arrives at the top of the seed tube at
the same rate it is removed from the ~ottom. At this
point, the system is in equilibrium, and the grain level
in the seed tube neither raises or lowers. In this
manner, the bin/plenum/distribution tube arrangement
works together with the seed tube/grain meter arrangement
to automatically control the flow and level of seed.
While the seed tube described above is most
advantageous when employed with a Cyclo drum, it may also
be used with a variety of other grain metering devices in
which a seed puddle is maintained.
While the distribution tube/seed tube
combination will regulate the flow of seed, there are
additional enhancements to the combination that reduce
the risk of "slugging," in which portions of the flexible
hose coupling the distribution tube and seed tube are
plugged. As long as the air velocity through the system
is high, the levitated grain will travel rapidly from the
bin to the Cyclo unit. The air velocity is not constant,
however, but varies according to the level of grain in
seed tube 234 in the Cyclo unit, as discussed above. At
CA 02243220 1998-07-15
-22-
various times, such as when the trac~or/cartlplanter
stops, no seed is planted, the Cyclo drum stops rotating,
and the seed tube fills up until it cuts off
substantlally all air flow. As the air velocity is so
reduced, the air eventually reaches a velocity at which
- it will no longer lift and move seed through the system.
~ It is this effect that allows seed tube 234 to
automatically control the amount of grain in the Cyclo
unit. Regulating flow in this manner may cause problems,
however. Flexible hose 200 is typically 10-40 feet long,
and typically has several ~'dips~' alonq its length.
Unless the flexible hose and the delivery tube are sized
correctly, seed may drop and slide down into these dips
when air velocity is reduced. This is called "slugging".
Once the seed gathers in these pockets in quantities
large enough to create a plug, almost all air flow
through the flexible hose will be cut off. To restore
air flow, a farmer must stop his tractor and manipulate
the flexible hose until these plugs of grain are removed.
To prevent slugging, the cross-sectional area
of the air flow path is reduced in the vicinity of the
end of the distribution tube that picks up seed. In the
embodiment illustrated here, this area reduction is
provided by employing a flexible hose 200 with a smaller
cross-sectional area than the cross-sectional area of
distribution tube 148 at its lower end. As seen in
Figure 10, flexible hose 200 is inserted into the end of
distribution tube 148 and is held in place by boot 201.
The end of flexible hose 200 is preferably between 2 and
8 inches from the lower end of distribution tube 148.
Flexible hose 200 preferably has an inner
diameter of 1.5 inches, and distribution tube 148 has an
inner diameter of 1.88 inches. This provides a flow path
with a larger cross-sectional area at the lower end of
the distribution tube, that transitions into a smaller
.. ,, ,.. . , "~.... .... ..
CA 02243220 1998-07-1~
--23--
cross-sectional area farther along the flow path. This
difference in cross-sectional area has the following
effect. Since the same quantity of air flows through
both the smaller flexible hose and the larger delivery
tube, the average velocity in the flexible hose is larger
- than the average velocity in the delivery tube. Thus,
whenever the air velocity through the system is reduced,
the lowest velocity at any particular time will be the
velocity in the delivery tube. Once the air velocity
drops below a threshold velocity called "pickup" velocity
in the distribution tube, seed will no longer be
levitated in the distribution tube to start its journey
to the Cyclo unit. Since the cross-sectional area of the
flexible hose is significantly smaller than the cross-
sectional area of the delivery tube, however, airvelocity in the flexible hose will still be above the
"pickup" velocity, and therefore any seed already in the
tube will continue moving through the flexible hose to
the Cyclo unit. The net effect is to purge the flexible
hose whenever the velocity drops below the "pickup"
velocity in the distribution tube thereby preventing
slugging.
Experimentation has determined that the minimum
area reduction should be at least 15% to provide this
self-purging anti-slugging effect under most operating
conditions.
There are effective limits to the area
reduction, however. Clearly, the larger the area
reduction, the larger the velocity difference and the
greater the purging capacity of the system. If the area
reduction is too great, however, the frictional losses in
the flexible hose are great, requiring a significantly
larger fan and motor than many particulate feeders are
currently equipped with. In addit on, as the area
reduction increases, the velocity in the flexible tube
CA 02243220 1998-07-1~
becomes quite high, accelerating even durable seeds to a
speed that will damage them when they arrive (and
suddenly stop) in the Cyclo unit or other similar
metering device. For this reason, the preferred upper
limit for the area reduction is 50%.
Thus, it should be apparent that there has been
- provided in accordance with the present invention a
pneumatic seed delivery system that fully satisfies the
objectives and advantages set forth above. Although the
invention has been described in conjunction with specific
embodiments thereof, it is evident that many
alternatives, modifications and variations will be
apparent to those skilled in the art. Accordingly, it is
intended to embrace all such alternatives, modifications
and variations that fall within the spirit and broad
scope of the appended claims. For example, the cart
illustrated in Figures 1 and 2 i5 supported by four
wheels. Similar carts are supported by as few as two or
three wheels. The cart of Figures 1 and 2 is shown as
having only two bins with corresponding metering devices.
Similar carts may have as many as four bins of which up
to three may be provided with a mechanical metering
device such as a metering cylinder and one to four may be
provided with the improved pneumatic system described
above. While the embodiment of Figures 1 and 2 shows a
bin tWith pneumatic or mechanical metering devices)
separate from the planter and coupled thereto by a hitc~,
thus providing a three-implement assembly (tractor
planter and cart), one implement may be eliminated by
disposing the bins and their metering systems directly on
the planter. This will allow farmers more
maneuverability as is typically required for smaller
acreage fields by eliminating the separate cart.
