Note: Descriptions are shown in the official language in which they were submitted.
1~88395
The present invention concerns an apparatus for hulling small
grains, particularly colza, rape and mustard grains, of the type com-
prising an enclosure provided at its upper part with a vertical chute
for feeding the grains, at its lower part with a hopper for discharging
hulled grains, and containing a rotary distributor formed from a hori-
zontal disc having a central circular cavity situated below the lower
end of the feeding chute and co-axial with the chute. This disc has
radial channels whose inlets communicate with the cavity and whose
outlets emerge in front of a cylindrical smooth-walled target, co-axial
with and surrounding the disc.
In hulling apparatus of this type, the disc rotates at high speed
so that the grains discharge into the circular cavity, under the action
of the centrifugal force generated, move along the radial channels and
are projected at the outlet thereof against the target which ensures the
hulling thereof.
It is known that the quality of hulling depends essentially on the
speed of the grains at time of their impact and on the slope of this
speed in relation to the target. Experience shows however that when the
flow of grains exceeds a maximum limit value, present conventional
apparatus does not have the required efficiency.
In fact, the main reasons for these difficulties come from choking
up of the channels which is caused by poor distribution of the grain
supply. This choking up is in fact the consequence of interactions
which the grains exert on one another and which are the greater, the
greater the flow. The grains which are not in contact with the bottom
of the cavity at the inlet of the channels or which, inside these
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latter, collide with other grains, have their output radial speed
reduced, which causes a greater slope of their path in relation to the
target and promote consequently their bouncing thereon, which offers a
resistance to hulling.
The present invention proposes improving the efficiency of hulling
apparatus of the above-mentioned type, with high throughput rates.
Accordingly, the invention is an apparatus for hulling small grains the
apparatus comprising an enclosure provided at its upper part with a
vertical grain supply chute, at its lower part with a hopper for dis-
charging the hulled grains and containing a rotary distributor formed
from a horizontal disc having a central circular cavity situated below
the lower end of the feed chute and co-axial with the feed chute, the
disc being provided with radial cha~nels whose inlets co~municate with
the cayity and whose outlets emerge in front of a cylindrical smooth-
walled target, co-axial with and surrounding the disc, the supply chute
being surrounded by a cylindrical wall fixed to the upper part of the
enclosure, the lower end of the cylindrical wall extending into the
cavity of the disc to define with the bottom of the cavity a passage
having a height slightly greater than the diameter of the grains.
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Owing to the cylindrical wall surrounding the supply chute, the
grains now come into the channels and only form therein a single layer,
so that their interaction is greatly limited. Their interaction in the
channels will moreover be smaller the more numerous and the narrower the
channels. At the extreme, the grains will be in fact able to flow
following each other with a small gap therebetween and have no inter-
action.
This risks of choking up the channels are thus avoided, whereas the
quality of the hulling remains satisfactory.
It should moreover be noted that the side wall prevents the grains
from escaping accidentally from the cavity and reaching the discharge
hopper without being hulled.
Preferably, the lower end of the cylindrical wall is adjacent the
periphery of the cavity, which allows the number of grains able to
penetrate into the channels and consequently the efficiency of the
hulling apparatus to be increased.
According to one particular embodiment of the invention, the feed
chute is axially movable above the cavity.
When the lower end of the chute moves away from the bottom of the
2 cavity, the heap formed by the grains contained therein has a base whose
dimensions increase progressively to cover finally the whole of the
bottom of the tank; the grain supply flow increases of course as the
heap increases.
Thus, by judiciously moving the feed chute, it is possible to vary
the grain flow so as to adapt it to the optimum rotational speed of the
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disc and to allow the apparatus to operate under the most efficient
conditions.
An embodiment of the present invention is shown by way of example
on the accompanying drawing in which: -
Figure 1 is a vertical sectional view of the hulling apparatus
whose lower
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part has not been shown;
Figure 2 is an enlarged top view with parts cut away of a part of
the disc of the apparatus; and
Figure 3 is a sectional view along line III-III of Figure 2.
The hulling apparatus shown in Figure 1 is more particularly meant
for hulling small grains such as those of colza, rape and mustard. It
comprises an enclosure 1 provided at its upper part with a vertical
grain supply chute 2 and at its lower part with a discharge hopper 3 for
the hulled grains.
Inside the enclosure there is disposed a rotary distributor formed
by a horizontal disc 4 mounted on the upper end of a shaft 5. This
shaft is mounted inside a protecting sleeve 6 by means of bearings
7 only one of which is visible in Figure 1, and is capable of being
driven by a drive member 8 associated with a speed variator. At its
upper end, sleeve 6 carries a plate 9 fixed by means of bolts and nuts
10 to radial brackets 11 integral with the side-wall of the enclosure.
Disc 4 comprises a central circular cavity 12 situated below the
lower end of chute 2 and radial channels 13 whose inlets emerge into
cavity 12 and whose outlets emerge in front of a smooth-walled cylindri-
cal target 14, which is co-axial with the disc which it surrounds and is
fixed on the ~adial brackets 11.
As can be seen in particular in Figure 2 and 3, channels 13 are
closed at their upper end by a cover 15 fixed to disc 4 by means of
bolts 16.
In accordance with the in~ention, the feed chute 2 is axially
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movable and is surrounded by a cylindrical wall 17 fixed to the upper
part of the enclosure. The lower end of the wall 17 penetrates inside
cavity 12 with the bottom of which it defines an annular passage 18
having a height slightly greater than the diameter of the grains. In
the example shown in Figure 1, it is moreover located adjacent the
periphery of cavity 12.
The operation of the hulling apparatus will now be described while
assuming that the chute is in its low position shown with continuous
lines.
The grains to be treated, stored in a reservoir not shown, fall by
gravity into chute 2 and reach rotary disc 4 while forming therein a
heap E whose base partially covers the bottom of cavity 12. With the
rotation of the disc, the grains are subjected to a high centrifugal
acceleration so that those located at the periphery of the base of the
heap are directed in the form of a single layer, towards the periphery
of the cavity, follow passage 18 and travel at high speed along radial
channels 13 at the outlet of which they are projected against target 14.
Cylindrical wall 17, while preventing the grains from accidentally
escaping from cavity 12, regularises their flow which may then remain as
a single layer inside the channels. The interactions between the
different grains are thus greatly limited, which avoids the choking up
of said channels and avoids the risks of bouncing on the target. It
will be noted that by increasing the number of the channels and by
constructing them with a width only slightly greater than the diameter
of the grains, these interactions may again be reduced since in this
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case the grains can only move one after the other in the different
channels.
When chute 2 is in its high position shown with a dotted dash line
in Figure 1, the grains from a heap E' whose base covers the whole of
the bottom of cavity 12. The supply flow is here much greater than when
the chute is in its low position. However, the risks of choking up and
bouncing are again avoided with wall 17 which forces the grains to
penetrate into the channels while forming only a single layer.
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