Note: Descriptions are shown in the official language in which they were submitted.
CA 02221381 2004-09-15
Low Splash Inlet For Screw Conveyor
This invention relates to a screw conveyor system for moving material from one
location
to another, especially a conveyor system for moving particulate matter such as
seed,
fertilizer or grain from a hopper to another location. Screw conveyors, as is
known,
incorporate a rotatable screw for propelling particulate, granular or other
free-flowing
material along the length of the conveyor system in an axial direction as
determined by
the sense of rotation of the screw. The propulsion of that material is
achieved by the
successive turns of a continuous helical blade, known in the art as flighting,
which in
most cases encircles, is secured on, and radiates from a central driving shaft
forming part
of the screw and which is arranged for rotation by an appropriate power
source.
Most modern farms typically use power-operated screw conveyors of various
sizes to
move grain, seed and/or other particulate from unloading areas to storage
bins, transport
trucks and planters. One particular example is the use of a screw conveyor to
load seed
and/or fertilizer from a grain truck into the tanks of an air cart. Portable
screw conveyors
used for this purpose generally have an integral inlet hopper having low sides
to allow the
conveyor inlet to be placed in a plurality of locations where space may be
limited; for
example, the inlet hopper can be disposed below an outlet of an air cart tank
with the
conveyor outlet placed above a grain truck. One problem associated with the
use of this
type of conveyor having a hopper with low sides, is that the exposed screw
within an
open hopper will have a tendency to throw or splash grain out of the hopper,
especially
when the level of the particulate within the hopper is reduced so that only a
portion of the
screw is covered. Another problem is that many conveyor systems tend to leave
a
quantity of particulate matter in the bottom of the hopper after use thus
leading to
wastage or the need to find an alternate method of transporting the leftover
grain.
It is an object of the invention to provide a screw conveyor system that
substantially
reduces the problem of grain being thrown upward instead of being efficiently
fed into
the screw conveyor inlet.
CA 02221381 2004-09-15
Summary of the Invention
In accordance with the invention, there is provided a screw conveyor system
for moving
material from one location to another, comprising a rotatable conveyor screw
defining a
longitudinal axis of rotation; an elongated tubular housing accommodating a
portion of
the rotatable conveyor screw such that rotation of said conveyor screw effects
movement
of said material along and within said housing, said housing having an open
inlet end
with said conveyor screw extending beyond the open inlet end of the housing,
said
tubular housing being shaped such that an upper portion of the tubular housing
inlet end
extends beyond lower portions of said housing and overlies a portion of the
conveyor
screw adjacent said inlet end so as to partially confine the material and
minimize upward
throwing of the material by the conveyor screw during rotation thereof.
In accordance with another aspect of the invention, there is provided a screw
conveyor
system wherein said open end of the tubular housing has at least a portion
inclined at an
angle with respect to the longitudinal axis of the conveyor screw whereby to
provide said
housing extended upper portion which overlies said portion of the conveyor
screw.
In accordance with another aspect of the invention, there is provided a screw
conveyor
system further comprising a hopper having a lower portion for receiving the
rotatable
conveyer screw and a portion of the housing including said open inlet end, the
shaping of
the inlet end of the tubular housing serving to define an effective material
feed length at
the lower portion of the hopper that is greater than an effective material
feed length
defined at an upper location within said hopper.
As will be seen, one embodiment of the invention provides a smaller inlet
along the top
of the exposed conveyor screw extending beyond its housing than about the
bottom of the
conveyor screw extending beyond the housing; the special shaping of the
housing reduces
the amount of spillage upwardly out of the hopper when the screw is conveying
material;
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CA 02221381 2004-09-15
further, this provides an adequate feed length and at the same time, reduces
the size of
hopper safety screen required.
Brief Description of the Drawings
Exemplary embodiments of the invention will now be described in conjunction
with the
drawings, in which;
Fig. 1 is a side view of a screw conveyor, an inlet end being inserted into
the bottom of a
hopper, in accordance with the invention;
Fig. 1 a is a side view of a screw conveyor, in accordance with an alternative
embodiment
of the invention; and
Fig. 2 is a detailed side view shown partly in cross-section of a typical
conveyor system
having an integral hopper and in a slanted orientation.
Detailed Description
Turning now to Fig. l, the screw conveyor 10- includes a rotatable conveyor
screw 12
having helical flights housed within and extending beyond an inlet end of
tubular housing
14. Housing 14 extends through an opening 18 at a lower end of an open topped
hopper
16. In this exemplary embodiment, the longitudinal rotation axis 15 of the
conveyor
screw 12 lies substantially horizontally and is coincident with the
longitudinal axis of the
tubular housing 14. However, in other preferred embodiments, the conveyor
screw 12
and integral hopper 16 are inclined as shown in Fig. 2. As the screw 12 turns,
material
within the hopper adjacent the conveyor screw 12 is transported in the
direction of
product flow, indicated by an arrow shown pointing to the right. The open
inlet end of
the housing 14 as defined by its terminal edge 17 is slanted, indicated by an
angle A
relative to a vertical line that is perpendicular to the longitudinal axis 15.
This slanted
end ensures in the embodiment of Fig. 1 that the effective feed length 12 at
the bottom of
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CA 02221381 2004-09-15
the conveyor screw 12, is greater than the effective feed length l, at the top
of the
conveyor screw 12. The slanted end also provides an inlet end portion which
overlies
part of the screw 12 to inhibit upward throwing or splashing of particulate
materials out
of the hopper during the conveyance process.
Generally, in conventional hoppers, the effective feed length 1 Z at the
bottom of the
conveyor screw 12, is equal to the effective feed length 11 at the top of the
conveyor
screw 12 and the material within the hopper tends to follow the flighting in a
direction
perpendicular to the shaft, out of the hopper, producing a "boiling" effect.
This effect is
considerably lessened and in some instances is nearly obviated in the portable
low-sided
hopper in accordance with the embodiment shown in Fig. 1 where 1 ~ < 1 Z.
Advantageously, less material is wasted by being thrown out of the sides of
the hopper
16, and furthermore, material is more efficiently provided to the conveyor
screw 12 for
transport. In a preferred embodiment, the angle 0 shown in Fig. 1 is between
25 degrees
and 60 degrees.
In an alternative embodiment of the invention, shown in Fig. 1 a, a back wall
15 of the
hopper may be slanted at a substantially same angle 0, to allow 1 ~ = 12,
still however,
providing the advantage of the above-described slanted housing open end. Yet
still
further, the hopper back wall 15 can be sloped such that 11 > 12. Hence, the
feed lengths
can be varied considerably relative to one another; it is the extended upper
portion of the
housing 14 provided by the slanted end that reduces the "boiling effect"
during operation
and at the same time ensures an ample feed length for efficient operation and
low product
spillage.
Fig. 2 shows a more detailed illustration of the conveyor system described
above and
shown in Fig. 1 except that the screw conveyor and hopper combination are
shown in an
inclined orientation. Components similar to those described with reference to
Fig. 1 are
shown and identified by the same reference numbers with an added "prime".
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CA 02221381 2004-09-15
Of course, numerous other embodiments may be envisaged without departing from
the
spirit and scope of the invention.
