Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR METERING SEEDS
This invention is in the field of agricultural seeding implements and in
particular a seed
metering apparatus for a seeding implement.
BACKGROUND
In the agricultural industry, considerable research has been done and is
ongoing to
determine optimum plant spacing for various crops to provide maximum yields.
This
desired spacing in turn giVCS a desired plant population of plants per unit of
area, such as
a square foot or acre. In order to translate this into a usable form for the
farmer, the
average number of seeds in a unit of weight, such as pounds, is determined for
an average
sample of representative seeds. The number of desired plants per acre is then
translated
into a seeding rate of pounds per acre.
Seed sizes and weights as N,vell as desired plant populations vary
dramatically between
different crops. A typical corn variety has large sized seeds and may have
about 1.200
seeds per pound, while a typical wheat variety has smaller medium sized seeds
and may
have about 12,000 seeds per pound, and a typical canola has very much smaller
sized
seeds and may have about 120,000 seeds per pound.
Similarly desired plant populations also vary dramatically. A typical
population for corn
may be about 0.5 plants per square foot (22,000 plants per acre), for canola
about 5 plants
per square foot (220,000 plants per acre), and for wheat about 2.5 plants per
square foot
(1,100,000 plants per acre). Canola seed can cost $10 or more per pound, and
so current
research is showing that the traditional plant population of .1.0 plants per
square foot can
be reduced to 5 per square foot if fairly evenly distributed.
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=
Ideally these plants are spaced equally in all directions in a grid like
arrangement
however in practice a given seeder has a fixed spacing between the furrow
openers and so
the spacing between the rows of plants is fixed for any particular seeder,
typically for a
modem minimum tillage air seeder these row spacings are 10-12 inches. With the
spacing between rows fixed, altering the seeding rate alters the spacing
between seeds in
a row.
With a wheat crop on a 12 inch row spacing-, there should be about 25 seeds
per foot of
row, and the distance between seeds is then less than 1/2 inch. With canola
there should
be about 5 seeds per foot of row, and the distance between seeds is 21/2
inches.
With corn there should be about 0.5 seeds per foot of row, and the distance
between seeds
24 inches. For max imiun yields however, corn is seeded at a wider row
spacing,
typically 30 inches or more, with a row type planter. Corn is sometimes seeded
with a 12
inch spacing air seeder by only using every other furrow opener so the row
spacing is 24
inches and there are thus about 1.0 seeds per foot of row.
Thus it can be seen that to get an even plant spacing, the spacing is much
more critical for
corn than for either wheat or canola, while the spacing of canola seeds is
more critical
than for wheat. To achieve the desired even spacing, singulating metering
devices are
commonly used for planting corn. These typically comprise pockets or recesses
on a
rotating, disc and take the seeds from a seed tank one at a time and drop them
into a
furrow. For example United States Patents 5,848,571 to Stufilebeam et al.
and
7.513,200 to Friestad disclose meters for dispensing seeds. United States
Patent
6,564,729 Petzoldt discloses a vacuum seed metering assembly wheret individual
seeds
are held to apertures in a drum by suction and each seed is released into an
associated
distribution tube when the aperture passes into a release area.
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hi contrast, seed metering devices for seeding wheat and canola typically work
on more.
of a bulk principal. One typical type of seed metering device includes a
rotating feed
roller with recesses spaced evenly along the outer surface of the roller. The
feed roller is
typically mounted below the feed opening at the bottom of a seed tank and
configured
such that the intake side of the roller is inside the feed opening exposed to
the seeds in the
tank and the outer output side is above the furrow in a conventional seeder,
or in an air
seeder is above the air stream that carries the seeds to the furrow openers to
be deposited
in the ground. As the roller rotates, seeds fill the recesses and are canied
from the seed
tank and. dropped into the furrow in a conventional seeder, or are fed into
the air stream
of an air seeder.
United States Patent Application Number 2012/0279430 of the present inventor
Beaujot
discloses a seed metering device for an air seeder where the feed roller is a
thin notched
feed disc mounted to the shaft. An upright shield plate. extends across the
feed opening
adjacent to the shaft and defines a disc slot having a width corresponding to
a thickness
of the disc. A portion of the feed disc extends through the disc slot forward
of a front face
of the shield plate. The feed shaft, feed disc, and shield plate are
configured such that the
shield plate seals the feed opening, and such that an intake portion of the
feed disc is in
the feed opening exposed to seeds. Rotation of the. feed shaft carries seeds
out of the seed
container in the disc notches and into a seed receiver. A lower dispensing
portion of the
= disc slot is widened to reduce seed damage in pinch zones where the feed
disc passes
though the slot.
SUMMARY OF THE INVENTION
The present disclosure provides an apparatus for metering seeds singly that
overcomes
problems in the prior art.
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The present disclosure provides a seed metering apparatus for dispensing seeds
of
substantially equal size. The apparatus comprises a seed container with a feed
opening in
a bottom thereof. and a feed shaft rotatably mounted in a substantially
horizontal
orientation and extending substantially front a right side of the feed opening
to a left side
thereof. A feed disc is mounted to the feed shaft such that the feed disc and
feed shaft
rotate together, and a plurality of disc teeth extend from a perimeter of the
feed disc and
are substantially equally spaced along the perimeter of the feed disc. The
disc teeth
define disc recesses therebetween, the disc recesses sized to accommodate a
single seed.
I 0 A shield plate extends from the right side of the feed opening to the
left side thereof in an
upright orientation from a bottom edge thereof to a top edge thereof, the
shield plate
substantially parallel to and adjacent to a front side of the feed shaft,
wherein the shield
plate substantially seals the feed opening., The shield plate defines a disc
slot having a
width corresponding to a thickness of the feed disc such that the feed disc
extends
through the disc slot with seeds substantially prevented front passing between
edges of
the disc slot and the feed disc. The shield plate and disc slot are configured
such that a
front portion of the feed disc extends forward from the feed shaft through the
disc slot,
and a rear portion of the teed disc is located in the feed opening exposed to
seeds in the
seed container. The width of the disc slot is selected to allow a largest
dimension of the
seeds to pass through the disc slot in the disc recesses. The feed shaft
rotates such that
the disc recesses on a dispensing edge of the feed disc move. forward through
a
dispensing portion of the disc slot. First and second guide plates extend
rearward from a
rear face of the shield plate, inner faces of the guide plates substantially
aligned with right
and left edges of the dispensing portion of the disc slot and adjacent to
right and left sides
of the disc recesses on the dispensing edge of the feed disc, the first and
second guide
plates staggered such that outer edges of the guide plates alternately push
seeds away
from opposite side edges of the disc recesses such that a single seed occupies
each disc
recess moving forward through the dispensing portion of the disc slot. A seed
receiver
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located under the disc slot is configured to receive seeds dropping from the
disc recesses
as the disc recesses pass the front face of the shield plate.
The metering apparatus uses guide plates to move seeds out of the pinch zones
to reduce
seed damage. and eliminates the need of a large shield relief area. The
predictability of
the flow of seeds dispensed is increased and pulsations are reduced. Seeds can
be
dispensed singly as well.
DESCRIPTION OF THE DRAWINGS
While the invention is claimed in the concluding portions hereof, preferred
embodiments
are provided in the accompanying detailed description which m.ay he best
understood in
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 schematic side view of an embodiment of a seed metering apparatus
of the
present disclosure;
Fig. 2 is a schematic front view of the embodiment of Fig. 1.:
Fig. 3 is a schematic front view of the embodiment, of Fig. 1 with the guide
plates
removed to show how seeds jam and become datnaged in a pinch one between the
disc teeth and the sides of the disc slot;
Fig. 4 is schematic front view of a seed metering apparatus of the prior art
showing the
bottom portion of the disc slot widened to prevent seed damage;
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Fig. 5 is a schematic side view of the embodiment of Fig. 1 with a shunt block
added
under the disc teeth to provide dispensing of single seeds;
Fig. 6 is a schematic bottom view of the installed shunt block of Fig. 5;
Fig. 7 is a schematic side view of an alternate embodiment of a seed metering
apparatus of the present disclosure where the seeds are dispensed from the top
side of
the feed disc_
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Figs. 1 and 2 schematically illustrate an embodiment of a seed metering
apparatus 1. of
the present disclosure for dispensing seeds 3 of substantially equal size. The
size of each
seed 3 will fall within a known range for the particular crop and thus be
substantially
equal within the meaning of the present disclosure, and the apparatus 1 will
commonly be
configured to meter seeds of a selected crop, such as corn, soybeans, etc.
The apparatus 1 comprises a seed container 5 with a feed opening 7 in a bottom
thereof.
A feed shaft 9 is rotatably mounted in a substantially horizontal orientation
and extends
substantially from a right side of the feed opening 7 to a left side thereof,
and is rotated
by a drive 11. A feed disc 13 is mounted to the feed shaft 9 such that the
feed disc 13 and
feed shaft 9 rotate together. A plurality of disc teeth 15 extend from the
perimeter of the
feed disc 13 and are equally spaced along the perimeter of the feed disc 13.
The disc
teeth 15 define disc recesses 17 therebetween. and the disc recesses 17 are
sized. to
accommodate a single seed 3.
A shield plate 19 extends from th.e right side of the feed opening to the left
side thereof in
an upright orientation from bottom to top edges. The shield plate 19 is
substantially
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parallel to and adjacent to a front side of the feed shaft 9, and the shield
plate 17 seals the
feed opening 7. The shield plate 19 defines a disc slot 21 having a width W
corresponding to a thickness of the feed disc 13. The width W is selected to
allow the
feed disc 13 to extend through the disc slot 21 with a small clearance on each
side such
that the seeds 3 are prevented from passing between edges of the disc slot 21
and the feed
disc 13. The shield plate 19 and disc slot 21 are configured and positioned
such that a
front portion of the feed disc 13 extends forward from the feed shaft 9
through the disc
slot 21, and a rear portion of the feed disc 13 is located generally in the
feed opening 7
exposed to seeds 3 in the seed container 5.
The size of the disc recesses 17 and thc width of the feed disc 13, are
selected to
accommodate a single seed 3 and also the width of the disc slot 21 is selected
to allow the
largest dimension of the seeds 3 to pass through the disc slot 21 while in the
disc recesses
17. The feed shaft 9 rotates such that the disc recesses 17 on a dispensing
edge of the
feed disc 13 move forward through a dispensing portion of the disc slot 21..
In the
illustrated apparatus 1, the feed shaft 9 rotates in direction R such that the
dispensing
edge of the feed disc 13 is the lower portion of the feed disc 13 moving
forward through
the dispensing portion of the disc slot 21 that is located at a lower portion
of the disc slot
21.
First and second guide plates 23A, 23B extend rearward from the rear face 19R
of the
shield plate 19. Inner faces of the guide plates 23A, 23:B are substantially
aligned with
right and left edges of the lower dispensing portion of the disc slot 21 and
adjacent to
right and left sides of the disc recesses 17 on the dispensing edge of the
feed disc 13. The
first and second guide plates 23A, 23B are staggered such that outer edges
25A, 25B of
the guide plates 23A, 23B alternately push seeds 3 away from opposite side
edges of the
disc recesses 17 such that a single seed 3 occupies each disc recess 17 moving
forward
through the dispensing portion of the disc slot 21.
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Outer ends of the disc teeth 15 on the dispensing edge of the feed disc 13
pass through
the disc slot 21 at a tooth location 2'7. The first and second guide plates
23A, 23B have
inner edges 29A, 29B between the feed shaft 9 and the recesses 17, and the
outer edges
25A, 25B extend rearward from a front location that is at or below the tooth
location 27
and curve inward and rearward from. the front location on different first and
second arcs
as illustrated. The outer edge 25A of the first guide plate 23A is outward of
the outer
edge 25B of the second guide plate 23B. The outer edge 25A of the first guide
plate 23A
curves inward to a first idle location 31A that is inward of inner ends of the
recesses 17
and does not contact seeds in the recesses 17. The outer edge 25B of the
second guide
plate 25B curves inward to a second idle location 31B that is likewise inward
of inner
ends of the recesses 17, and the first idle location 31A is rearward of the
second idle
location 31B B.
.As the feed disc 13 turns in direction R, recesses 17 on the lower dispensing
edge of the
feed disc 13 move forward toward the disc slot 21 and any seed 3 partially
engaged in a
recess 17 and extending outward from the first side of the feed disc 13
gradually contacts
the curved outer edge 25A of the first guide plate 23A and is pushed either
out of the
recess 17 or into the recess 17 as the outer edge 25.A moves closely along the
first side of
the recess 17 and gradually engages the seed because of the curved shape. A
seed pushed
into the recess 17 in turn pushes any seed that is partially engaged in the
opposite second
side Of the recess 17 out of the recess 17, as there is nothing there to stop
it.
As the recess 17 moves further toward the disc slot 21, any empty recess 17
will in most
cases be filled by a seed 3 moving into same from the second side of the
recess 17 before
the outer edge 25B of the second guide plate 23B moves closely along the
second side of
the recess 17, at which point the recess 17 is sealed on each side by the
guide plates 23A,
23B. with a single seed 3 therein which drops down as the recess moves forward
of the
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front face 19A of the shield plate 19. A seed receiver 33 is located under the
disc slot 21
and is configured to receive seeds 3 dropping from the disc recesses 17. The
seed
receiver 33 directs the seeds into an air stream in an air seeder, or drops
them through a
conduit in a gravity seeder.
Fig. 3 schematically illustrates an issue that is addressed in the present
apparatus 1 by
providing the first and second guide plates 23A, 238. Without the guide
plates, a pinch
point zone is created in the area around a recess 17 advancing against the
rear face of the
shield plate 19 where a seed 3 is protruding partially beyond the sides of the
feed disc 13.
Such a seed is subjected to jamming against the shield plate 19 and being
damaged
Fig. 4 schem.atically illustrates how in the prior art a pinch relief portion
21A of the disc
slot 21 adjacent to a bottom edge of each feed disc 13 is widened to allow
seeds to pass
side hy7 side reduce ,jamming of seeds 3 between the edges of the disc slot 21
and the
1.5 teeth 15 on the feed disc 13, and reduce seed damage. The prior art
pinch relief works
satisfactorily for smaller seeds however because this pinch relief dimension
is related to
the maximum diameter of the seeds, the relief area becomes quite large for
large diameter
seeds like corn and soybeans, compared to small seeds like canola. When the
relief area
is large the flow rate is higher, less predictable and the rate pulses more
with each tooth
passage.
In contrast the guide plates 23A, 23B of the apparatus I. prevent jamming of
seeds, while
maintaining a single seed in each recess 17. To prevent jamming seeds between
outer
ends 15A of the teeth 15 and the bottom edge of the disc slot 21, the distance
between the
tooth location 27, where outer ends 15A pass through the disc slot 21, and the
adjacent
bottom end 35 of the dispensing portion of the disc slot 21 is substantially
equal to the
largest dimension of the seeds 3 such that seeds wili flow out the disc slot
21 under the
outer ends 15A of the teeth 15. The guide plates thus reduce the size of the
relief area
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required, and reduce the rate of seeds dispensed with each revolution of the
feed disc 13.
The flow rate is more predictable and pulsation is reduced.
In this configuration more than one seed will be dispensed into the seed
receiver 33 with
the passage of each tooth 15. A substantially constant flow of seeds into the
seed
receiver 33 will be achieved, however the addition of a shunt block 37 to
block off the
bottom of the disc slot 21 between the tooth location 27 and the bottom end 35
of the disc
slot 21 can provide a substantially singulated flow of a single seed 3 for
each recess 17
that passes through the disc slot 21.
The shunt block 37 extends across the bottom of the disc slot 21 between the
tooth
location 27 and the bottom end 35 of the disc slot 21 as schematically
illustrated in Figs.
5 and 6. The shunt block 37 extends rearward from the rear face. 19A of the
shield plate
19 in proximity to outer ends 15A of the disc teeth 15. The rear end 39 of the
shunt block
37 is tapered such that seeds 3 moving forward against the rear end 39 of the
shunt block
37 are shunted to one side of the shunt block 37.
The distance between the shunt block 37 and the outer ends 15A of the disc
teeth 15 is
much less than the largest dimension of the seeds 3 such that seeds are
substantially
prevented from passing forward between the outer ends I5A of the teeth 15 and
the top of
the shunt block 37, or between seeds 3A in the recesses 17 and the top of the
shunt block
37. On occasion a smaller seed may occupy a recess 17, and another seed may
wedge in
between the seed in the recess 17 and a tooth 15, and extend outward beyond
the outer
end I5A of the tooth. The shunt block 37 can be made of a relatively hard but
resilient
material to allow the wedged seed to depress the top of the shunt block 37
while moving
forward and out the disc slot 21 without damage.
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in the illustrated apparatus 1, the feed shaft 9 rotates in direction R such
that the
dispensing edge of the feed disc 13 is the lower portion of the feed disc 13.
Fig. 7
schematically illustrates an alternate apparatus l' where the feed shaft 9'
rotates in
direction R such that the dispensing edge of the feed disc 13' is an upper
portion of the
feed disc 13' moving, forward through the dispensing portion of the disc slot
21' located at
a top of the disc slot 21'. The guide plates 23A', 23B' are at the top of the
fed disc 13' and
the shunt block 37' is above the feed disc 13' in this version. Also a seed
retainer 41 is
operative to guide the seeds from where they exit the disc slot 21' at the
front face 19F' of
the shield plate 19' to the seed receiver 33'.
The present invention provides a seed metering apparatus for dispensing larger
seeds with
improved flow characteristics, and dispensing of single seeds at selected
intervals can be
provided if desired.
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.
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