Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1054861
~C~O~O~D 0~ ~N3 INV~NrlON
This invention concerns a seed metering device
for the singling and accurate spacing of seeds fed from
the hopper of a seed drill. The device is especially,
but not essentially, adapted for dealing with elongated
or lozenge-sha~ed seeds, such as wheat, oats and barley.
SUMMARY OF THE INVENTION
The object of the invention is to provide a seed
metering device which is capable of accurate and rapid
operation so as to enable a seed drill to which it is
attached to be towed at high speed over ground to be
sown.
This object is achieved, according to the invention,
b~ providing a seed metering device comprising a seed
hopper, having a base which is in part sealed by two
sets of contra-rotated circular rotary members driven
about adjacent substantially horizontal axes, one set
of the said rotary members having the form of Vee-belt
pulleys each provided with a plurality of regularly
spaced single seed receptors at the base of its Vee-shaped
peripheral slot, the other set of rotary members having
complementary Vee-shaped protruding rims of high friction
material penetrating upper parts of the said slots with
close tolerance to sweep open faces of the seed receptors
and at least one masking plate mounted in the seed hopper
and having an arcuate edge closely spaced from the said
open faces of the seed receptors, said masking plate
being located beneath the location at which the Vee-
shaped protruding rims sweep said open faces of the seed
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receptors to maintain single seeds within the receptors
until the seeds reach a position at which said seeds
can be released from the seed receptors.
A further ob~ect of the invention is to provide a
metering device for cereal seeds in which case the seed
receptors are formed as elongated recesses and are
sligh-tly longer and broader than the average dimensions
of the seeds being sown.
To ensure positive ejection of the seeds at the
position at which the seeds are released, according to
another ob~ect of the in~ention a continuous groove
narrower than the seed receptor width is preferably
provided in the middle of each Vee-shaped slot and a thin
stationary blade penetrates the groove to force seeds
radially outwards as their receptors are dri~en past
its leading edge.
The Vee-shaped protruding rims which sweep the open
faces of the seed receptors are preferably made from
hard rubber, bonded to the peripheries of the second set
of rotary members and ground to ensure the close
tolerance above referred to.
A comb-like plate whose teeth likewise enter the
Yee-shaped slots with close tolerance seals the hopper-
base against escape of seeds past the ad~acent peripheries
of the first set of rotary members.
A similar plate co-operates with the second set of
rotary members to prevent them from carrying seeds out
of the hopper.
The first set of rotary members, which may be termed
spacing wheels are preferably of considerably greater
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diameter than the second set, which may be termed singling
wheels and the latter are preferably driven at higher
rotational speed.
, Drive to the two sets of wheels may be derived from
'a ground-wheel and is in any case related to the speed of
the seed drill over the ground to ensure a desired spacing
between released seeds.
The spacing wheels are preferably easily removable
and replaceable by similar wheels having seed receptors
of dimensions suited to seeds of differing shape and size.
In operation cereal seeds drop into the seed
receptors in the momentarily upper portions of the spacing
wheels, being necessarily guided into alignment with
those receptors by the Vee form of the peripheral slots
co-operating with their own elongated shape.
me sweeping action o~ the singling uheels flicks
away surplus seeds from the receptors, the masking plates
retain the singled seeds in their receptors as they
rotate dow,n to the release point where they fall by
gravity or are positively ejected by the narrow blades
to fall to the ground in accurately spaced rows.
BRIF,F DESCRIPTION OF THE DRAWINGS
The above and other objects of the invention are
embodied in the following description of a prototype seed
metering device which is illustrated in the accompanying
drawings in which:-
Figure 1 is a diagrammatic side elevatlon o~ the
device;
Figure 2 is a section on the line II-II of Figure 1;
and
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1054861
Figure 3 is a detailed section of half a spacing
wheel.
DESCRIPTION OF PREFERRED EMBOPrMENT
The illustrated prototype device has two spacing
wheels and two singling wheels, a full scale production
version will have many such devices arranged in staggered
rows in a wheeled chassis.
In the drawings a pair of spacing wheels 2 are shown
mounted for rotation on a shaft 4 journalled in a casing
6.
A pair of singling wheels 8 are mounted on a shaft
10 similarly ~ournalled in the casing 6 and extending
parallel to the shaft 4.
The singling wheels 8 are dri~en via spindle 10, and
drive is transmitted to the spacing wheels through
sprockets 14 and 16 and a chain 18 tensioned by a jockey 20.
The singling wheels 8 are about half the diameter of
the spacing wheels and are driven at three times the speed.
They have Vee-shaped protruding rims 22 tipped by hard
rubber.
The spacing wheels 2 are similar to ~ee-belt pulleys,
and the rims 22 enter the Vee-shaped peripheral slots 24
in the wheels 2 with close tolerance.
The slots 24 are formed with regularly spaced elon-
gated recesses 26, which constitute single seed receptors,
and deeper central narrow grooves 28 as shown in Figure 3.
The recesses 26 are dimensioned to suit particular
~arieties of seeds, and in the prototype are 14 mm. long
and 3.5 mm. deep for dealing with oats.
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The casing 6 cons'itutes the lower outlet portion
of a seed hopper of similar width to the casing and a
seal is made with the spacing wheels 2 by a comb-like
plate 30, whose teeth have a similar profile to the
rims 22 of the singling wheels 8. A similar plate 3
seals the casing 6 with the singling wheels.
A stationary masking plate 34, whose arcuate edge
36 is closely spaced from the base of the slot 24 of each
spacing wheel, retains a sèed within each recess 26
until it reaches the release point 38.
A narrow profiled blade 40 penetrates each groove
28 with its leading edge radially inward of the bases
of the recesses 26 and positively ejec*s any seed which has
not fallen under its own weight at the release point 38.
In operation, seeds are presented to the recesses
26 in the spacing wheels 2 as they are driven past the
base of the casing 6. A single seed, orientated by the
Vee shape of the peripheral slot of the spacing wheel,
falls into each recess and any surplus seed is flicked
away by the contra-rotating rubber tips of the rim 22 o~
the co-operating singling wheel 8.
The seed is now retained in its receptor by the
arcuate-edge of the complementary masking plate 34 until
it reaches the release point 38, where it can ~all to
the ground.
Should the seed be held by friction in its receptor,
it is positively ejected by the narrow blade 40 and is then
directed (like a gravity-released seed) to prepared ground.
It will be understood that the in~en-tion i5 not
~0 restricted to the details of the preferred form described
by way of example which may be modi~ied without departure
~rom the scope of the appended claims.
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