Note: Descriptions are shown in the official language in which they were submitted.
CA 02491081 2004-12-29
AIR SEED METER
FIELD OF THE INVENTION
The present invention relates to improvements in air seed meters of the type
used
to meter and "singulate" seeds in row units for agricultural planters. Air
seed meters
which use atomospheric pressure on the seed reservoir side of a rotating disc
and a
pressure below atmospheric pressure on the "vacuum" side (the pressure
differential
maintaining seeds on a rotating disc from a seed reservoir to a discharge
location), are
frequently referred to as "vacuum" meters, to distinguish them from seed
meters which
use a differential pressure generated by atmospheric pressure and a pressure
greater than
atmospheric pressure to retain the seeds on the disc ("positive pressure"
meters).
The principles of the present invention relate to air seed meters in general,
whether the pressure differential securing the individual seeds to a disc is
created by a
sub-atmospheric pressure on the vacuum side of the disc, or whether a positive
pressure
(above atmospheric pressure) is generated in the seed reservoir to secure the
seeds to the
disc. However, subsequent discussion and description will relate to the
"vacuum" type
of meter. Persons skilled in the art will readily be able to adapt or apply
the structure
and operation disclosed to the positive pressure type of meter. As used
herein, the word
"singulate" refers to separating one seed from a group or large number of
seeds, typically
stored in a reservoir. Singulation is typically used for more expensive seeds,
to conserve
costs, and to achieve the desired plant spacing for achieving maximum yield
potential.
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BACKGROUND OF THE INVENTION
Air seed meters have been known in the art for some time. One current
commercial air seed meter uses an enclosure for the disc having a first
housing section
forming a reservoir for the seeds and receiving and enclosing the seed side of
the disc,
and a second housing section, connected to the first housing section for
contacting and
enclosing the vacuum side of the disc. The second housing section forms a
vacuum
chamber, in the case of an air meter employing suction to secure the seeds to
the disc.
In most cases, two housing sections form the overall meter casing, are in the
form
of flat, circular end walls (i.e. disc-shaped) with generally cylindrical side
walls. The
housing sections or halves are mounted with the centers of the end plates
concentric
with the axis of rotation of the disc. Moreover, in prior art meters, for the
most part,
a seal is formed between the vacuum cover and the seed disc.
The seed disc is driven typically for rotation about a generally horizontal
axis. As
the disc, having spaced seed apertures located circumferentially about the
disc, is rotated
through the seed reservoir, seeds are picked up and attached to an aperture by
means
of a pressure differential between the seed reservoir and the vacuum chamber.
The
seeds are held to the disc by the pressure difference as they pass through the
seed
reservoir. The seed is passed to a discharge area which, typically, is located
adjacent
a downwardly facing chute formed as a tangential channel in the meter housing.
In prior art air seed meters which seek to establish a seal between the vacuum
housing and the rotating disc, the seal extends around the periphery of the
portion of the
vacuum housing which forms the actual vacuum chamber. That is, a portion of
the
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vacuum chamber typically is devoted, in prior art devices, to a point for
releasing the
seeds sequentially into the discharge chute. This is done, in some cases, by
having the
seeds pass into a region adjacent the discharge chute. The "vacuum" (i.e.
lower pressure)
side of the disc, as it passes adjacent the discharge chute, naturally is
exposed to air
pressure near, but not always at atmospheric levels.
There are some difficulties associated with such arrangements. First, it is
desirable to establish atmospheric pressure at the actual point of discharge.
For
example, the higher the air pressure differential across the seed disc at the
moment of
discharge, the less would be the tendency to release the seed at the same
location
accurately. Any variation in the pressure differential across the seed disc at
the intended
point of release, will create variances in the spacing of the seeds upon
discharge and
deposit into the seed furrow. According to these structures, it became
necessary, in
some cases, to create an elaborate sealing mechanism which defined only the
boundary
of the vacuum chamber and excluded the region of release adjacent the
discharge chute.
Still further problems existed in that a "chimney effect" may be created in
the
discharge chutes of some existing meters. By this it is meant that as seed is
routed to
the release point in the discharge chute, it will be appreciated that the
reservoir side of
the seed disc is at approximately atmospheric pressure; and if measures are
not taken,
the interior of the seed reservoir may be at a slightly sub-atmospheric
pressure. This
also increases the likelihood that air is drawn up the discharge chute (i.e.
if the reservoir
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is at a pressure even slightly below atmospheric), resulting in a "chimney
effect"or
updraft of air in the discharge chute and requiring compensation. The chimney
effect
not only reduces the reliability of accurate seed release, and therefore
spacing, but
depending upon the velocity of air flowing in a reverse direction in the seed
discharge
chute, it might alter the discharge flight path of the seed, thereby further
affecting the
fall time (and ultimate spacing) of seeds.
Some prior art seed discs which use recesses or "cells" in the surface of the
disc
to capture and seat seeds experience another source of possible inconsistent
or unequal
seed spacing upon delivery to the furrow. Specifically where the seed is
required to
move axially of the disc (i.e. parallel to the axis of rotation) to release,
there is an
increased tendency for the seed to strike the wall of the discharge chute and
to ricochet
off the walls of the chute and to be delayed in release from the cell. This
effect creates
variation in the length of seed travel (and thus variations in delivery time)
from release
to deposit, and thus results in inconsistency in seed spacing in the furrow.
Other seed discs, which do not have recesses or depressions in the seed disc
for
retaining seeds, require the use an auxiliary device, some shaped like a
spider with wire
legs, to agitate and bring the seeds in the reservoir up to the speed of the
disc to
facilitate seating of the seeds on the disc.
Another difficulty with such prior art air meters as described above, is that
for the
most part, the seal between the disc and the vacuum housing is generally a
circular path
centered on the axis of rotation of the disc and located at the perimeter of
the disc. In
such structures, the portion of the disc engaging the circular seal tends to
create a
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narrow annular region of engagement between the seal member and the disc or
seal, thus
creating a narrow band of wear on the disc. This wear "ring" creating wear on
the disc
or seal, results in a variance between the surface of the disc which was
attempted to be
sealed and the contact surface of the seal, thus reducing the effectiveness of
some seals.
Moreover, such prior art structures rendered it difficult to clear the
interior of the
vacuum chamber as well as the exterior from fine particles, dust, dirt and
chips or
broken segments of seeds that may have cracked (collectively referred to as
"debris" or
"fines"). Such particles could pass through or obstruct the apertures in a
seed recess and
may even accumulate between contacting surfaces where it was difficult, due to
the
20 nature of some prior devices, to clear the debris. Some prior art devices,
such as
disclosed in U.S. Patent 6,247,418, created tiny slots between a seal of the
vacuum
housing and the disc so that air could flow across the seal through the groove
in the
adjacent surface of the disc between the contact surfaces to clear the disc
and seal
surface of fine particles. However, the cross section of such slots tended to
reduce, with
diminished clearing effect, as the sealing member wore into the surface of the
disc,
thereby reducing the dimensions in and effectiveness of the clearing
passageways.
SUMMARY OF THE PRESENT INVENTION
The present invention includes a vacuum cover which has a semi-toroidal shape,
but which is not a completely closed shape. By this, it is meant that the
vacuum
chamber extends partially but not completely about the periphery of the main
seed
housing of the meter, (thus making the vacuum housing "segmented" in the sense
that
it does not extend completely about the circumference of the seed reservoir
housing).
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Moreover, the vacuum cover of the present invention does not have a flat, disc-
shaped
outer wall and a generally cylindrical side wall so as to match, in general,
the housing
for the seed reservoir. Rather, in radial cross section, the vacuum housing of
the present
invention has a general U-shape, forming an enclosure extending partially
about the
periphery of the disc and having spaced, opposing end walls.
The shape of the vacuum housing provides a closed wall having two perimeters
for engaging the remainder of the meter. The outer perimeter of the vacuum
housing,
which is generally circular, is located outwardly of the seed openings in the
disc and that
conforms in general to the outer perimeter of the seed housing and provides a
flange for
mounting to the seed meter housing and partially enclosing the disc. The inner
edge of
the vacuum cover lies inwardly of the seed openings in the disc, and is also
curved to
define a central opening which is generally circular. The center of this
central opening
in the vacuum cover, however, is not concentric with the center of the disc,
which
defines the axis of rotation of the disc. The central opening of the vacuum
cover is
smaller in diameter than the disc; and the center of the central opening is
off-set or
eccentric relative to the axis of rotation of the disc which is at the center
of the disc.
This arrangement has the advantage that the region of engagement between the
disc and
the vacuum cover defined by the contact area between the two is not a narrow,
annular
or circular region on the disc. Rather, as the disc rotates, the circular
contact area
between the inner edge of the vacuum cover and the disc moves progressively in
a non-
concentric manner about the disc, thus distributing or spreading out the total
area of
contact between the two, and reducing the wear per unit area of contact.
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The inner curved contact surface of the vacuum cover is provided with several
spaced segments, each including a series of circumferential grooves (that is,
they are
spaced in alternate fashion with contact surfaces from the center toward the
periphery).
In the illustrated embodiment, each sealing segment has three such grooves
which form
curved areas which do not engage the disc. This design further reduces the
surface
contact between the disc and the associated portion of the vacuum meter
housing and
enhances the sealing function of each sealing segment while reducing wear on
the disc.
Moreover, generally radial slots are provided between adjacent sealing
segments
of the inside edge of the vacuum cover. These slots separate the grooved
sealing
segments and extend generally radially of the central opening of the vacuum
cover, but
they are slightly inclined relative to a radius. Specifically, the slots
extend outwardly
and slightly incline in the direction of rotation of the disc when proceeding
from an inner
location to an outer location. Further, the slots are enlarged in cross
sectional area
proceeding from inner to outer locations. Thus, the slots are less likely to
become
25 clogged with fines; and the fines are delivered in a direction facilitating
their being
entrained in the air flow into the vacuum chamber from which they are
evacuated. This
permits the innermost central opening of each clearing slot to clear the
central open area
of the disc by permitting fines to be drawn into the vacuum chamber and
evacuated. It
also prevents the fines from getting caught between contacting adjacent
surfaces of the
disc and vacuum cover.
It will thus be appreciated that the combination of spaced, grooved sealing
segments on the inner contact edge of the vacuum cover, together with the
inclined,
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radial slots separating the sealing segments do not form a complete seal
between the
cover and the disc. Rather, what is formed is what is referred to as an "air
dam" or
controlled air barrier between the external atmosphere and the interior of the
vacuum
chamber, permitting a continuous, controlled flow of air from the atmosphere
into the
interior of the vacuum chamber for purging the contact region between the disc
and
inner edge of the vacuum cover of debris and clearing the central, exposed
portion of the
disc adjacent the disc/vacuum cover contact. This arrangement also aids in
controlling
undesired leakage of air, and it extends the useful life of the disc.
Another area in which the present invention improves on prior designs of air
seed
meter is in establishing a more uniform pressure differential between the two
surfaces
of the seed disc by establishing a uniformity of atmospheric pressure
throughout the
seed reservoir. This is accomplished by designing air inflow to the seed
reservoir to
compensate to air lost to the vacuum. In one aspect, a slotted insert is
provided to
overlay a large aperture on the back wall of the seed housing. The slots are
sized such
25 that they contain the seeds in the reservoir, but they are extended in
length to permit air
to flow inwardly over an extended region. Secondly, an opening is formed in
the side
wall of the seed housing adjacent the entrance of the discharge chute to
reduce any
'chimney" effect described above. In addition, if desired, the disc may be
provided with
additional apertures located in the central portion of the disc, which is
located in the
central opening of the vacuum cover when the disc and vacuum cover are
assembled.
In combination, these features permit make-up atmospheric air to flow into the
reservoir
over a distributed area to equalize atmospheric pressure within the seed
reservoir over
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a wide range of operating conditions.
Another area of improvement in the present invention is in the singulation of
seeds. This is accomplished by locating the seed cells extending to the
periphery of the
disc so the seeds do not have to move axially of the disc when released to
clear the cell,
and by providing, for each seed cell, a seed aperture or orifice extending
through the disc
for communicating the vacuum source with the reservoir for securing the seed.
In
addition, adjacent each seed orifice (in the corn disc) communicates with a
pair of seed
recesses in the reservoir side of the disc including a circumferential recess
extending in
the direction of rotation, and a radial recess extending radially inward
toward the center
of the disc. The circumferential recess facilitates seating of a seed and
guidance of the
seed into communication with the seed orifice and then securing the seed once
seated
and singulated. The radial recess extends from the seed orifice toward the
center of the
disc and it promotes removal of duplicate seeds, in combination with the
singulator
mechanism.
The singulator mechanism of the present invention comprises a series of three
brushes extending radially inwardly of the disc and inclined slightly in the
direction of
rotation of the disc when proceeding inwardly of the periphery of the disc.
Each brush
comprises two sets of bristles and tends to dislodge a duplicate seed if it is
present and
competing for a seat. It has been found that the inclusion of three separate,
spaced
brushes enhances the accuracy of the meter by rejecting duplicates, usually at
the first
two brush stations, yet permitting each orifice to be filled with a seed.
The brushes of the singulator are mounted in a single body which is adjustable
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radially of the seed disc by means of a lever accessible, externally of the
meter. The
brushes are arranged for progressively more aggressive singulating action. The
adjustment lever is easily accessible and quickly, conveniently and accurately
manipulated. The outer edge of the seed disc is beveled so that the
singulating brushes
may extend more easily inwardly of the disc to engage and dislodge duplicate
seeds from
the seed cells, and to facilitate radial movement of the seeds as they are
released.
Other features and advantages of the present invention will be apparent to
persons skilled in the art from the following detailed description of the
illustrated
embodiment wherein identical reference numerals will refer to like parts in
the various
views.
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BRIEF DESCRIPTION OF THE DRAWINGS
As used herein, "right" and "left" refer respectively to the left and right
side of a
planter row unit or meter from the viewpoint of an observer standing to the
rear of the
planter and facing in the direction of travel. Further, "front" refers to the
direction the
observer faces - i.e. the direction of forward travel of the planter. These
references are
optional and solely for convenience of description.
FIG. 1 is a perspective view of a planter row unit incorporating the present
invention taken from the upper, rear and left side of the unit;
FIG. 2 is a left side elevational view of the row unit of FIG. l;
FIG. 3 is an upper, frontal and left side perspective view of an air seed
meter
incorporating the present invention;
FIG. 3A is a lower, rear left side perspective view of the seed meter of FIG.
3;
FIG. 4 is a perspective view taken from the upper, rear and left side of the
meter
of FIG. 3 with some components shown in exploded relation;
FIG. 4A is a fragmentary close-up perspective view of the seed singulator of
the
meter, with the components in exploded relation;
FIG. 5 is a perspective view of the meter of FIG. 3 taken from the front and
left
side, again with some components in exploded relation;
FIG. 5A is a lower perspective view of the singulator with components in
exploded
relation;
FIG. 6 is a lower, left side perspective view of the vacuum cover;
FIG. 7 is an interior elevational view of the vacuum cover of FIG. 6;
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FIG. 8 is a lower, rear interior perspective view of the vacuum cover of FIG.
6;
FIG. 9 is an upper, rear perspective view of the interior of the housing of
the
meter of FIG. 3;
FIG. 10 is a view similar to FIG. 9 with the brush separator insert assembly
in
exploded relation;
FIG. 11 is a perspective view of an alternate seed disc of the meter of FIG.
3,
showing the reservoir side of the disc;
FIG. 12 is an enlarged, fragmentary elevational view of a section of the
periphery
of one seed disc of FIG. 3A showing the seed cells;
FIG. 13 is an enlarged, transverse cross-sectional view of a peripheral
segment
of a seed disc taken through the sight line 13-13 of FIG. 12.
FIG. 14 is an enlarged, fragmentary, perspective view of the periphery of the
seed
disc of FIG. 12 showing seeds seated in adjacent seed cells;
FIG. 15 is a side view of a portion of a seed disc and the singulator
mechanism
in operative relation;
FIG. 16 is a view similar to FIG. 15, with the singulator adjusted to a
location
further from the seed retention opening;
FIG. 17 is a side view of the vacuum cover and seed disc with a portion of the
structure sectioned along the sight line 17-17 of FIG. 17A;
FIG. 17A is a side elevational view of the reservoir side of the seed disc and
vacuum cover in assembled relation;
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FIG. 18 is an elevational side view of a portion of the seed disc of FIG. 3
adjacent
the release point of the seeds and showing the seed discharge for an idealized
release;
FIG. 19 is a left side elevational view of the air seed meter of FIG. 1;
FIG. 20 is a cross section view taken through sight line 20-20 of FIG. 19; and
FIG. 21 is an enlarged view of the portion of FIG. 20 enclosed within the
chain
line loop of FIG. 20.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
Referring first to FIG. 1, reference numeral 10 generally designates a planter
row
unit incorporating the air seed meter of the present invention. Briefly, the
row unit 10,
aside from of the inventive air seed meter is known in its general aspects to
persons
skilled in the art. The row unit includes a U-bolt mount generally designated
11 for
mounting the row unit to a conventional planter frame or tool bar, as it is
sometimes
called, which may be a steel tube of 5 by 7 inches (although other sizes are
used, as
well).
25 The mount 11 includes a faceplate generally designated 12 which is used to
mount left and right side parallel linkages, each linkage being a four-bar
linkage such as
the left one seen in FIG. 1 and generally identified by reference numeral 14.
The double
linkage is sometimes described as having upper parallel links and lower
parallel links,
and the rear ends of all four parallel links are pivotally mounted to the
frame of the row
unit generally designated 15. The frame 15 includes a support for a seed
hopper 16,
as well as a structure including a shank weldment generally designated 17 for
mounting
a pair of ground-engaging gauge wheels, one of which is shown at 18, as well
as a
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furrow closing unit generally designated 19 which includes a pair of inclined
closing
wheels. The row unit also includes a pair of furrow opener discs designated 26
in FIG.
2.
As is well known in the art, seed is placed in the hopper 16 and fed to a
meter,
a portion of which is seen at 20 in FIG. 1. The meter 20 singulates and
deposits seed
as the row unit is pulled along, into a furrow prepared by a conventional disc
opener 26
placed between and extending in front of the gauge wheels 18. The furrow is
then
closed, after the seed is deposited, by the closing wheels 19.
Turning now to FIGS. 3 and 3A, there is shown, in perspective view, a seed
meter
20 constructed according to the present invention. The seed meter 20 includes
a
housing 21 which receives seed from the hopper 16 and forms a seed reservoir,
and a
removable vacuum cover generally designated 22.
Referring to FIGS. 4 and 5, the major components of the seed meter 20 are
shown
in exploded relation. To the lower left of FIG. 4 is the vacuum cover 22 which
is
located on the outer or left side of the meter. A seed disc 23 is driven by a
hub 25.
Hub 25 engages the disc 23 and drives it in rotation (counter clockwise as
seen in FIG.
4) about a horizontal axis identified by reference numeral 28. The hub 25 is
mounted
to a shaft 29 which is fitted with a bearing 31. The shaft 29 is provided with
a pair of
bores 33, 34 which receive pins 35, 36 respectively. Pin 35 mounts the hub 25
to
the shaft 29 by means of a collar 38, which is also provided with a pair of
apertures one
being designated 39 in FIG. 4. The apertures 39 of the collar 38 are aligned
with the
aperture 33 of the shaft 29 to receive the pin 35. The aperture 34 and pin 36
of the
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shaft 29 are used to mount the shaft 29 to a drive coupling on the planter.
The drive
shaft is designated 40 in FIG. 2.
Referring now to the hub 25, it includes a plate 41 which includes three
lobes,
each having a tapered drive lug 42. The tapered drive lugs 42 are received in
elongated
apertures 44 of the disc 23 (see FIG. 3). The apertures 44 are spaced equally
from a
central opening 45 of the disc 23 which receives the collar 38 of the hub 25.
The taper
of the lugs 42 is such that they are wider toward the base (i.e. plate 41) so
that the lugs
engage and enter the openings 44 of the disc 23 and urge the disc toward the
vacuum
cover 22 when the meter is assembled. In this manner, the disc 23 is closely
adjacent
20 and urged toward an inner flange of the cover 22, to be described, so that
there is
contact between the two. When the vacuum is applied, the disc 23 is drawn into
more
intimate contact with the cover 22 to maintain a sub-atmospheric pressure
("vacuum")
within the cover 22, as will be further described within. The drive coupling
connects to
the shaft 29 from the outer side of the meter, as seen in FIG. 3 by the
operator or
maintenance personnel and connecting the planter drive to the meter.
It will be observed from FIGS. 3 and 4 that each of the drive lugs 42 is
elongated
laterally and inclined relative to a radial line extending from the axis of
rotation 28. In
the illustrated embodiment when viewed from the left (outer) side of the meter
and as
seen in FIG. 4, the rotation of the disc is counter-clockwise. The inclination
of the drive
lugs 42 relative to a radial line or plane is that the direction of elongation
of the lugs
extends closer to the axis of rotation when moving in the angular direction of
rotation.
The receiving apertures 44 of the disc 23 are similarly oriented and have the
same cross-
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sectional shape. This arrangement insures that the disc cannot be mounted in
driving
relation with the hub 25 if the surfaces of the disc 23 are reversed. In other
words, the
vacuum surface of the disc (the surface 23B seen in FIG. 4) must face
outwardly and the
reservoir side of the disc 23A in FIG. 5) must face inwardly of the meter in
order for
proper driving engagement between the hub and disc to be established. This
prevents
improper assembly of discs in the meter. Moreover, the drive lugs 42 are
tapered in an
axial direction, being reduced in cross-section proceeding axially toward the
disc.
Referring to FIGS. 4, 9 and 10, the meter housing 21 includes an upright back
wall 46 which is circular and disc-like, and a cylindrical side wall 47 which
extends
toward the vacuum cover 22 and receives the cover for mounting by means of
four
mounting lugs 48 received in bosses 48A formed on side wall 47, and described
further
within. The back wall 46 includes a first opening 51 through which seed is
admitted
from the hopper for forming a reservoir of seed within the housing 21, bounded
on the
left (outer) side by the non-vacuum (or "reservoir") side 23A of disc 23.
Referring to FIGS. 4, 5, 9 and 10, an optional, adjustable plate 152 may be
included to form a gate to adjust the seed inlet opening 51 from seed chute 69
to the
seed reservoir. The plate 152 includes two parallel slots 156 which receive
bosses 159,
which guide the plate 152 in adjusting the seed inlet opening 51. A third slot
157
extends parallel to slots 156 and receives a thumb screw 150 which is threaded
into the
rear wall 46 of the meter housing to secure the plate 152 to the desired,
adjusted
position.
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The rear wall 46 also includes an integrally mounted central boss or journal
53
into which the bearing 31 of the shaft 29 is pressed for mounting the drive
hub 25. A
second, larger opening 55 is formed in the back wall 46 of the housing. A
plastic
member referred to as an "insert", in the general form of a half disc, and
generally
designated 58 in FIG. 4, is located to cover the opening 55 in the back wall
46. The
insert 58 is sized to be received within the housing 21; and the insert 58 is
provided
with a series of elongated, narrow, spaced slots generally designated 60 (FIG.
9) which
extend laterally across the opening 55 in the rear wall of the meter housing
21. When
the insert 58 is assembled to the housing 21 (by means of male and female
connectors
62, 63 in FIG. 10), the slots 60 extend across the opening 55 and permit air
to enter
into the housing 21 so as to provide a uniform distribution of air at
atmospheric
pressure within the seed reservoir. Referring particularly to FIG. 9, the
insert 58 is
shown in its mounted position. The width of the slots 60 is small enough to
prevent
seeds from passing through. Different inserts, with different slot widths may
be used
for seeds of different size. The slots, together with air inlet apertures 52
in the disc 23
and an opening 54 extending partly in the side wall 47 and rear wall 46 of the
housing
21, cooperate to establish uniform air pressure at atmospheric level
substantially
throughout the entire seed reservoir and the interior of the housing 21,
including the
point of seed release.
A seed singulator device 61, discussed further within, is mounted to the
exterior
of the side wall 47 near the top of the housing 21. The lower, forward portion
of the
side wall 47 of the housing 21 is formed to define three sides of a seed
discharge spout
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65. A discharge cover, seen at 66 in the lower left hand portion of FIG. 4 and
assembled
in FIG. 9, is secured to the discharge spout 65 to enclose the discharge area.
Clips 67
of cover plate 66 are received in latches 68 formed in the housing 21 adjacent
the
discharge spout 65. A conventional seed tube (not seen in the drawing) is
mounted
below the discharge spout 65 for receiving and delivering seed to the open
furrow, as
is known in the art.
An inlet seed chute 69 is formed integrally with rear wall 46 and includes a
mounting flange 70 for mounting the meter to the bottom of the seed hopper 16.
Chute
69 funnels seed from the bottom of the hopper through seed inlet opening 51,
sized by
the adjustable gate 152 into the seed reservoir formed by the housing 21 and
the seed
disc 23. Insert 58 includes an integral bristle brush 72). The brush 72 forms
a lateral
wall defining the seed reservoir to prevent seeds from spilling directly into
the discharge
chute 65.
Turning now to FIGS. 3, 3A and 6-8, the vacuum cover 22 includes an outer
shell
or wall designated 73 has a generally toroidal form which is truncated or
incomplete in
the sense that the shell 73 extends circumferentially from a first end wall 74
to a
second, opposing end wall 75. The opposing end walls 74, 75 are spaced to
define an
open sector generally designated 78 in FIG. 7 in which the vacuum cover does
not
extend, except for an axially extending continuation wall 83, to be described.
Because
the disc rotates counter clockwise in FIGS. 3 and 3A, the end wall 74 may be
thought
of as a beginning or starting wall, and the wall 75 may be termed a final or
terminating
end wall.
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The shell 73 includes an upper wall 80, an outer side wall 81 and an inner
side
wall 82 which, together with end walls 74, ?5, form an enclosure, except for
vacuum
coupling 92. Inner side wall 82 of the vacuum cover has a generally
cylindrical form
which continues between the starting end wall 74 and the terminating wall 75,
forming
the continuation section 83 which adds strength to the vacuum cover. Wall
section 83
defines a raised portion or bridge 84 which permits debris to be discarded, as
will be
described. The corners of the shell 73 of the vacuum chamber may be beveled,
as seen
in the drawing, or curved or squared. Thus, the vacuum chamber 85A (FIG. 7) is
in the
form of a closed tunnel having a general C-shape or crescent shape when viewed
from
the left, extending from start wall 74 to the terminating end wall 75, and
enclosed by
the shell 73 which has a generally inverted U-shape in cross section (FIG.
20), with the
distal ends of the legs of the "U" adjacent the disc 23. The outer and inner
sidewalls 81,
82 of the vacuum cover may be generally cylindrical or frustoconical. However,
their
respective inner disc-engaging edges are circular with the centers spaced from
one
another. Thus, the cross-sectional area of the vacuum cover taken in a radial
plane
(relative to the center of the opening 85) increases progressively from the
start wall 74
and the end wall 75 to the vacuum coupling 92. This has the effect of
balancing or
equalizing the pressure within the vacuum chamber at different circumferential
locations
about the circular arrangement of seed cells.
The inner or central portion of the vacuum cover 22 is open -- this area being
designated 85 in FIGS. 6, 7 and 8. Thus, referring to FIGS. 3 and 3A, the
adjacent or
"vacuum" side of the disc 23 is open to the exterior may be seen and accessed
through
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CA 02491081 2004-12-29
the opening 85 from the left or outer side of the meter. This is considered
advantageous
for a number of reasons. First, the center of the vacuum side 23B of the disc
is readily
available for visual inspection for wear or damage or for cleaning. The disc
may be
color-coded for different seeds, and the color is readily accessible by the
farmer.
Moreover, as will be discussed, the air flow into the vacuum chamber is able
to be
controlled and augmented so that there is a continuous flow of air through the
vacuum
chamber to evacuate fines and seed remnants, not only from within the vacuum
chamber, but from the exposed portion of the disc 23 adjacent and within
opening 85
formed by the inner wall 82 of the vacuum cover 22. Further, for discs of
certain seeds,
Tp it may be desirable to include air inlet apertures such as those seen at 52
in FIGS. 3 and
4 in the central portion of the seed disc to 23 admit air into the seed
housing 21 to
augment air being introduced through the slots 60 of the insert and through
opening 54
in the rear wall of housing 21, all of which cooperate to equalize the
interior pressure
of the seed reservoir to atmospheric pressure.
T5 Referring primarily to FIG. 6, it will be recalled that the disc 23 rotates
in a
counter-clockwise direction relative to the vacuum cover. 22 when viewed from
the
exterior. A seed cell or aperture enters the vacuum chamber beneath the start
end wall
'74 of the cover 22 and rotates counter-clockwise. The vacuum promotes seed
placement in a seed cell (to be described), and the disc continues to rotate
past the
20 second or terminating end wall 75 where the disc then exits the vacuum
chamber (see
seed orifice '79 in FIG. 3A) and re-enters the atmosphere in the open or
uncovered sector
78 between the opposing walls 74, 75. It will be appreciated that when a seed
orifice,
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CA 02491081 2004-12-29
such as the one designated 79 in FIG. 3A passes beneath the terminating end
wall 75
of the vacuum chamber, atmospheric pressure is immediately applied to the
vacuum side
of a seed cell, i.e. across the disc, and the seed is released into the
discharge spout 65
with a reliable and repeatable action, thus improving the accuracy of seed
spacing.
Returning to FIG. 6, it will be observed that the start end wall 74 of the
vacuum
chamber, is provided with an inclined section designated 77, the lower edge of
which
engages the vacuum side of the disc (which rotates counterclockwise as seen in
FIG. 6).
The inclined wall section 77 acts as a scraper to remove debris from the
portion of the
disc passing into the vacuum chamber, and directs that debris downwardly
through the
open sector 78 of the vacuum cover 22, where the debris falls from the meter
unobstructed
An inner, lower edge of the inner side wall 82 of the vacuum cover 22 is
provided
with a formed, beveled surface 87 which tapers inwardly toward the disc 23 and
toward
the center of the central opening 85 of the vacuum cover 23. This beveled
surface 87
provides an inclined, circumferentially curved surface to clear and clean the
adjacent
outer surface of the disc (which is the vacuum side) of any foreign matter by
scraping.
Materials which are thus loosened and removed from the vacuum side 23B of the
disc
23 also fall freely downwardly through the raised portion 84 of the
continuation wall
83 of the cover through the open sector 78 of the housing 21.
A peripheral mounting flange 90 is formed at the base of the outer side wall
81
of the vacuum cover 22. The outer flange 90 is not continuous about the vacuum
cover
in order to leave the open 'sector 78 free of obstruction. The mounting flange
90 defines
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CA 02491081 2004-12-29
a series of keyhole slots such as those designated 91 for fitting over and
coupling with
associated mounting studs or lugs 48 (FIG. 5) secured in bosses 48A formed on
the
sidewall 47 of the housing 21. The studs 48 have enlarged heads (see 50 in
FIG. 3A).
To assemble the cover 22 to the housing 21, the flange 90 of the cover is
placed against
the edge 49 of the housing, with the studs 48 aligned with associated slots
91, and with
the heads 50 received in the larger aperture of an associated keyhole slot 91.
The cover
is then rotated counterclockwise (in the direction of disc rotation) until the
base of the
studs enter the narrow portion of the keyhole slot (see FIG. 6), thereby
locking the cover
to the housing. A manual clockwise rotation of the cover unlocks it from the
housing
and permits removal of the cover without the need for power assist or any
tools
whatever.
The upper, central portion of the top wall 80 of the cover 22 is formed into a
coupling 92 to receive a hose or conduit connected between the vacuum cover 22
and
the source of suction, which typically is a fan driven by a hydraulic motor,
in the case
of a planter.
Referring now to FIGS. 7 and 8, the under or marginal surface 95 of the
beveled
flange 87 of the inner wall 82 of the vacuum cover 22 is a flat surface which
engages
the adjacent surface of the disc 23 and remains in contact with that surface
in a manner
such that the radial inner edge 94 of the beveled flange 87 brushes or scrapes
away
debris from the part of the vacuum surface of the disc 23 which it engages.
The center
of the central opening 85 of the cover 22 is offset from the center or axis of
rotation of
the disc. In the illustrated embodiment, the center of the central opening 85
is below
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CA 02491081 2004-12-29
the axis of rotation of the disc 23. By this arrangement, the inner marginal
or contact
surface 95 of the cover which contacts the disc does not form a narrow contact
band
and corresponding narrow wear pattern as would occur if the center of the
central
opening 85 of the vacuum cover 22 were located on or near the axis of rotation
of the
disc. Rather, due to the eccentric location of the opening 85 relative to the
axis of
rotation of the disc, the wear pattern broadens out beyond the thickness of
the contact
surface 95 adjacent the inner beveled edge 94 as the disc rotates, thus
broadening the
contact region and reducing the wear on any one given region of the disc which
contacts
the inner marginal surface of the cover.
The marginal surface 95 the beveled flange 87 can be seen to be comprised of a
series of segments separated by radial slots 107. The marginal surface 95 is
divided
into five sectors or sections in the illustrated embodiment, designated
respectively 100,
101, 102, 103 and 104 in FIG. 7. Each segment 100-104 has a set of three
circumferential grooves 96, 97, 98; and the sectors are divided by a series of
radially
outwardly extending slots designated 10?. The radial slots 107 have, as seen
in FIG.
7, an increasing width (and cross sectional area) proceeding away from the
center of the
central opening 85. The axis of each slot 107 is inclined slightly away from a
direct
radial line and toward the direction of rotation of the disc (clockwise in
FIG. 7). This
promotes the flow of debris into the vacuum chamber.
The purpose of the arrangement of radial slots 107 and sealing segments 100-
104 is to create an air dam or barrier between the cover and the disc so that
air from
the central opening 85 flows between the individual segments 100, 101, 102,
103 and
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CA 02491081 2004-12-29
104 of the air dam, through slots 107 in a controlled and continuous manner,
suctioning into the vacuum chamber, as the disc rotates, any fines or other
debris
capable of passing through the slots 107 and into the vacuum chamber 85A where
these
materials are then evacuated by passing through coupling 92 and ultimately
expelled by
the vacuum fan.
The inner surface of the vacuum housing is made rough or textured by
conventional means, so as to reduce any tendency to have seed treatments or
powder
adhere to it. Discs of different thickness may be used without modification of
the rest
of the structure, as will be described.
Turning now to FIGS. 11-16, the seed disc 23 is seen to comprise a series of
circumferentially located seed cells, generally designated 110. The seed cells
110 are,
in the illustrated embodiment, spaced about and immediately adjacent to the
periphery
of the seed disc 23. As will be further described within, it is considered an
important
feature of the present invention that the seeds are delivered, at the point of
release,
directly tangentially outwardly of the disc, rather than having an axial (that
is,
downward and to the left in FIG. 11 ) component of motion. As explained above,
such
an axial component of motion is likely to lead to ricocheting of the seeds off
the walls
of the discharge chute, thereby adding uncertainty as to the flight time of
the seed from
the point of release to the location of lodging in the base of the formed
furrow, and
rendering the spacing of seeds non-uniform.
As seen in FIG. 11, the disc 23 (which may be used for peanuts, for example)
rotates in the direction of the arrow 115, hence, the side of the disc 23 seen
in FIG. 11
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CA 02491081 2004-12-29
is the reservoir side 23A of the disc 23, whereas the vacuum side of the disc
is seen, for
example, in FIG. 3A. The outer edge of the disc may be tapered or beveled, as
seen best
at 116 in FIG. 13.
Referring particularly now to FIGS. 12 and 13, There is shown a disc which may
be used for corn seed. Each of the seed cells 110 includes a circumferential
recess 111
and a radial recess 112 in communication with a seed orifice 113 which
communicates
the vacuum to a seed seated in a cell. The circumferential recess 111 is thus
extended
or directed in the direction of rotation. In other words, if a seed is located
adjacent the
outer perimeter of the disc 23, it will first encounter the circumferential
recess 111.
The function of the circumferential recess 111, which deepens or is
progressively
recessed from the leading edge 111A toward the seed orifice 113, is to promote
the
travel of a seed toward the lower portion of the seed cell and the adjacent
opening of
the seed orifice 113. As seen in FIG. 12, the seed orifice 113 extends from
the base of
the seed cell down to the vacuum side of the disc, designated 23B in FIG. 13.
The
25 lower portion of the seed orifice 113 is chamfered as at 117.
As best seen in FIG. 12, the outermost, peripheral portion of the
circumferential
seed recess 111, designated 111B, is open and leads into the chamfer 116.
Thus, when
a seed is released from the cell, it is free to move tangentially outwardly
immediately (as
can be appreciated from FIG. 13), unobstructed by any portion of the disc,
under both
centrifugal force and gravity, because the seed is released at a location of
approximately
8:00 o'clock when viewing the vacuum chamber, and considering the location of
the
terminating end wall 75 of the vacuum cover.
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CA 02491081 2004-12-29
The radial recess 112 of each seed cell facilitates the dislodgement or
separation
of duplicate seeds -- that is, the purpose of each seed cell is to allow the
singulator to
isolate and secure (i.e. "singulate") a single seed in each cell.
Referring now to FIG. 14, a close up view of adjacent seed cells is seen,
individual
seeds designated S are received in, and secured by means of the vacuum to the
disc via
the seed orifice 113.
Turning now to FIGS. 4, 5, 15 and 16, the singulator device 61 will be
described.
The singulator includes a holder 119 which may be of a synthetic or plastic
material.
Three sets of brush bristles designated 120, 121 and 122 are carried by and
secured
to the holder 119. Each set of bristles comprises a brush, and they all may be
similar,
so that only one need be described. The brush 120, which is the leading brush
set
includes first and second sets of bristles or "tufts" 123, 124 (FIG. 5A) which
extend or
are inclined downstream in the direction of rotation 115 relative to a radial
line.
Turning now to FIGS. 4A and 5A in particular, the rear of the brush holder 119
is provided with a generally cylindrical extension 125 which defined a radial
opening
125A which receives a spring 126. The extension 125 is received on and secured
to a
bracket 127 fixed to the outer surface of side wall 47 of the housing 21. The
bracket
127 includes a lower semi-cylindrical seat 128 for spring 125, and an upright
back
127A defining an aperture 127B. The upper end of spring 126 bears against the
bottom of brush holder 119 and urges it radial away from the central axis of
rotation.
A shaft or pin 130 extends radially of the brush holder 119 and rotatably
receives an
adjusting lever 153 which is held in place by a cap 151 having a flange 151A
which
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CA 02491081 2004-12-29
include an aperture 151B which receives the shaft 130 of the brush holder. The
flange
151A of cap 151 extends through the opening 125A of bracket 127. A cap screw
154
is placed through an aperture in the flange 151A and aperture 127B of bracket
127 to
hold the adjusting assembly in place and maintain the spring 126 in
compression for the
entire adjustment range.
The brush holder 119 is assembled to the bracket 127 by having the bracket
placed in the opening 125A of the rear extension 125 of the brush holder. The
extension 125 is shaped to receive and engage the edges of the seat 128. This
permits
the brush holder 119 to slide in a radial direction relative to the axis of
rotation of the
disc, but restraining axial, circumferential or rotational motion of the brush
holder. It
also facilitates brush replacement. Turning to FIGS. 4A, 5A and 15, the brush
holder
119 is held in a predetermined radial position against the bias of the spring
126 by
means of adjusting lever 153 which is rotatably received on pin 130 and
includes a cam
surface 135 (FIG. 5) which extends in a generally helical path about the axis
of the pin
130. The outer limit position of the adjusting lever 153 is fixed by the cap
151, which
allows the lever 153 to rotate. Spring 126 exerts a radial outward force
against the
brush holder 119 and lever 153. A pin 138 is fixed in the radial shaft 130
(FIG. 15)
and extends beneath the cap 151.
As the handle 133 of lever 153 is rotated clockwise (looking radially toward
the
axis of rotation), the portion of cam surface 133 furthest from the axis of
disc rotation
engages the pin 138, thus enabling the spring to raise the brush holder and
brushes to
a raised position as seen in FIG. 16. As the lever 153 is rotated
counterclockwise, pin
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CA 02491081 2004-12-29
138 engages the portion of cam surface 132 closest to the axis of rotation,
thus lowering
the brushes to the position of FIG. 15.
It will be appreciated that the brushes are guided into the reservoir side 23A
of
the disc 23 and retained in that position without straddling the edge of the
disc due to
the bevel 116 at the edge of the disc. In other words, the beveled edge 116
insures that
the bristles of the brushes 120-122 will be on the reservoir side of the disc
23 for
various levels of adjustment, as seen in FIG. 16, where the brushes are
located such that
their distal ends are adjacent the periphery of the disc, to that of FIG. 15
wherein the
brushes are more deeply set and the ends of the brushes are radially inward of
the seed
orifices.
Still referring to FIG. 15, on the left side of the disc 23 there are seed
cells
emerging from the seed reservoir, some of which have a single seated seed, but
others
of which have duplicate seeds. As a seed cell bearing a duplicate, such as the
cell
generally designated 139 in FIG. 15 encounters the first brush set 120, it can
be seen
that one of the seeds is dislodged and the other seed may be moved slightly
from the
seed orifice. The upper seed, however, is returned to the seed orifice due to
the suction
of the vacuum when the seed passes the brush set 120, captured by the radial
recess of
the cell. That is, during this movement, the seed rests in the radial recess
139A of the
seed cell 130. It has been found that the use of a single brush does not
consistently and
reliably eliminate all duplicates. A second brush (the two tufts are
considered as one
brush) downstream of the first, such as the one designated 121, removes
further
duplicates not corrected by the first brush, but again, the second brush set
does not
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CA 02491081 2004-12-29
eliminate all of the duplicates as desired. It has been found that by using
three brushes
(with each brush along the direction of disc motion extending further inward)
in
sequence and as illustrated in FIG. 15, singulation is performed reliably and
repeatedly
so that substantially all of the seed cells have one seed but not duplicates.
Turning now to FIGS. 3A and 17-19, the release of the seeds for delivery to
the
furrow will now be discussed. Turning first to FIG. 1?, the disc 23 is
rotating with the
near side of the disc in a downward direction. The cross section of the vacuum
cover
in FIG. 17 is at an angle relative to the end wall 75 as seen from FIG. 17A.
It will be
observed that prior to passing beneath the end wall 75 (see also FIG. 18), the
seed cells
are carrying single seeds. The seed immediately adjacent the end wall 75 is
designated
S in FIGS. 17 and 18. The interior of the vacuum chamber, 85A extends right up
to the
interior surface 75A of the end wall 75, maintaining the seed S secured to the
disc 23
by means of the vacuum being communicated to the seed through the seed
orifice, as
discussed above.
However, as soon as the seed cell passes beneath the end wall 75 (see seed
position S1 in FIG. 18), the vacuum is removed from the vacuum side 23B of the
disc
23 as seen in FIG. 17. In other words, the seed cell passes immediately into
the open
sector 78 defined as the angular position between the start end wall 74 and
the terminal
end wall 75 of the vacuum chamber and adjacent (but radially outward of) the
continuation 83 of the inner wall 82 of the vacuum housing. It will be
observed that
both sides of the disc are fully exposed to the atmosphere once a seed cell
passes
beneath the end wall 75, as further illustrated at 79 in FIG. 3A and 19 and
discussed
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above. As a result, the release of the seed is immediate because the retaining
vacuum
no longer retains the seed once it passes beyond terminating end wall 75.
The openings 54 and 55 in the seed housing and openings 52 in the disc all
cooperate to equalize the pressure within the seed reservoir. This produces a
more
uniform differential pressure retaining individual seeds on the disc and
reduces or
eliminates any "chimney" effect in the discharge chute.
Moreover, as illustrated in FIG. 18, which is a view taken from the reservoir
side
23A of the seed disc 23, once the seed cell passes to the atmosphere side of
the
terminating end wall 75 of the vacuum housing, the seed cell moves to the left
as it
continues rotating, but the seed itself, such as that designated S1 in FIG. 18
is free to
fall. Moreover, it is unencumbered by any lateral wall or rise in the seed
cell. In other
words, the seed is delivered freely and without obstruction tangentially
outwardly of the
rotating disc for an unencumbered and unobstructed delivery to the furrow, as
illustrated at S2 in FIG. 18.
25 FIG. 20 shows a diametric cross section of the meter, illustrating that the
radial
cross sectional area of the vacuum chamber increases when proceeding from the
start
wall 74 and the terminating wall 75 of the vacuum housing to the vacuum
coupling 92.
FIG. 21 illustrates the structure of the vacuum cover 22 which seals against
the
periphery of the opposing vacuum side of disc 23, and the engagement between
side
wall 47 of the seed housing 21 (which, together with vacuum cover 22 forms a
housing,
divided by the disc into a seed reservoir and a vacuum chamber) and the
peripheral edge
of the disc 23. In FIG. 21, the vacuum is not applied. When vacuum is applied
to the
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vacuum housing, the perimeter of the vacuum side of the disc engages the
opposing edge
of the vacuum cover to form a seal. Again, the seal is not an absolute seal,
and allows
some air to pass, but not in significant quantities.
Having thus disclosed in detail an illustrated embodiment of the inventions,
persons skilled in the art will be able to modify certain aspects of the
structure which
has been disclosed and to substitute equivalent elements for those described
while
continuing to practice the principal of the invention; and it is, therefore,
intended that
all such modifications and substitutions be covered as they are embraced
within the
spirit and scope of the appended claims.
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