Note: Descriptions are shown in the official language in which they were submitted.
CA 02311261 2000-06-09
TITLE: METHOD AND APPARATUS FOR HARVESTING CROPS
TECHNICAL FIELD
This invention relates to the harvesting of grain and seed crops of the kind
that are
conventionally harvested by means of a combine harvester. More particularly,
the invention
relates to systems, methods and apparatus for harvesting such crops.
BACKGROUND ART
The applicant herein has already disclosed a novel method of and apparatus for
harvesting
grain and seed crops that provide an alternative to the use of conventional
combine harvesters. In
this regard, reference is made to US Patent No. 5,794,423 issued on August 18,
1998; US Patent
No. 5,795,222 issued on August 18, 1998; and US Patent No. 5,873,226 issued on
February 23,
1999; all of these patents having been assigned to McLeod Harvest Inc. and are
referred to
collectively in the following description as "the McLeod patents."
A conventional combine harvester operates by carrying out all of the
harvesting steps in
the field on a continuous basis. The crop plants are cut, the cut plants are
threshed to separate
grain (or seeds such as peas, etc.), chaff and (inevitably) weed seeds from
the stalks, the grain is
then cleaned by separating it from the chaff and weed seeds, the grain is
delivered to a waiting
collection vehicle, and the stalks, chaff and weed seeds are returned to the
field. The
disadvantages of this are that (a) combine harvesters are very expensive to
purchase and to
operate; (b) they are not very efficient at cleaning the grain, so some grain
is lost and/or further
grain cleaning is required; and (c) chaff and weed seeds are returned to the
field, so that their
economic value is lost and weeds proliferate.
The concept underlying the systems disclosed in the above patents is that,
instead of
attempting to carry out all of the harvesting steps in the field, only the
step of threshing and
removing stalks is carried out, and the remaining product (a mixture of grain,
chaff and weed
seeds - referred to by the coined word "graff ') is collected and transported
to a fixed grain
cleaning site. The advantage of this is that the harvesting equipment may be
less complicated and
expensive than a conventional combine harvester, the cleaning of the grain may
be carried out
more efficiently at a fixed site, the economic value of the chaff and weed
seeds may be realized,
and the need for herbicides is reduced (because the weed seeds are collected
rather than being
returned to the field).
It has been found that this system is extremely effective, but inconveniences
have been
encountered in that graff has proven to be a difficult material to handle and
process. Since graff
contains a large percentage of chaff, it is bulky for its weight and it is
quite fibrous in
CA 02311261 2000-06-09
composition. Unlike grain collected by a combine harvester, graff does not
easily "flow" from
containers and it is difficult to move by conventional means, such as augers,
because it bridges or
binds within itself and does not flow internally to replace material that has
been removed from
the bottom of a container or pile of the material. In general, it can be said
that graff tends to pack,
clump, bridge, rat-hole and bind, rather than flow smoothly. This causes
problems not only when
the graff is stored in silos or the like before it is processed, but also
causes difficulties of material
flow within the harvesting device and transportation vehicles.
Moreover, graff is difficult to store because, if stored in the open, it tends
to blow away
and also to spoil if it gets wet. However, if stored in a container, it is
difficult to remove for the
reasons mentioned above.
Additionally, there is a need to improve the overall efficiency of the system
generally and
to improve the manner in which individual components orperate in order to
increase the
economic competitiveness of the system with conventional harvesting systems.
DESCRIPTION OF THE INVENTION
An object of the invention is to improve the efficiency and to reduce the
equipment cost
of carrying out a grain harvesting method of the type disclosed in the patents
mentioned above.
Another object of the invention, at least in its preferred forms, is to
overcome difficulties
caused by the poor flow properties of graff.
Another object of the invention, at least in broader aspects, is to optimize a
grain
harvesting system as opposed to a single grain harvesting machine such as a
conventional
combine harvester.
Another object of the invention is to reduce the operational cost of carrying
out a grain
harvesting method of the type disclosed in the patents mentioned above.
Another object of the invention, at least in its preferred forms, is to
improve the
effectiveness of the harvesting unit used to separate the graff from the crop
stalks in the field.
Another object of the invention, at least in its preferred forms, is to
improve the
effectiveness of the grain cleaning mill used to separate grain from the
remainder of the graff at a
fixed site and to process crop the residue.
According to one aspect of the invention, there is provided a method of
harvesting and
cleaning a plant crop, wherein the crop is cut from a field area and threshed
in a mobile
harvesting unit to produce stalks that are returned to the field area and
"graff', a mixture
including grain, chaff and weed seeds, which is collected within the
harvesting unit; the collected
graff is transferred periodically from the harvesting unit to at least one
vehicle and transported by
said at least one vehicle to a cleaning mill, and the graff is cleaned by the
cleaning mill to
CA 02311261 2003-03-07
produce a cleaned grain product and "millings", a mixture including chaff and
weed seeds;
wherein said graff, after harvesting of said crop, is first transferred
directly from said
harvesting unit to said vehicle and then directly from said vehicle to said
cleaning mill,
thereby avoiding temporary storage of said graff prior to cleaning of said
graff by said
cleaning mill.
What we mean by avoiding storage of the graff prior to cleaning is that the
graff is not
transferred to any temporary storage container or storage pile from the time
it is produced by the
harvester to the time it is cleaned by the cleaning mill. The graff is held
only in the harvester unit
and the vehicle, and is fed immediately into the cleaning mill. Consequently,
the use of
stationary surge bins and the like at the cleaning mill or other area is
specifically avoided. The
graff is fed directly from the harvesting unit to the vehicle, and directly
from the vehicle to a
receiving unit for the cleaning mill from which it is fed substantially
immediately and completely
into the cleaning mill.
Thus, according to another aspect of the present invention, there is provided
a system
for harvesting and cleaning a plant crop, which includes a harvesting unit for
cutting a crop
from a field area and for threshing the cut crop to produce stalks that are
returned to the field
area and "graff', a mixture including grain, chaff and weed seeds, which is
collected within
the harvesting unit; at least one vehicle for receiving collected graff from
the harvester unit
when the harvesting unit is at least partially full, and for transporting the
graff to a cleaning
2o mill; and a cleaning mill located at a site (yard area) remote from the
field area, for cleaning
the graff to produce a cleaned grain product and "millings", a mixture
containing chaff and
weed seeds; wherein the system includes means for transferring said graff
directly from said
harvesting unit to said vehicle and means for transferring said graff directly
from said vehicle
to said cleaning mill, thereby excluding any device for temporary storage of
the graff prior to
cleaning of the graff in the cleaning mill.
According to another aspect of the invention, there is provided a stationary
cleaning mill
for graff, comprising an entrance (usually located at an elevated position)
for the graff, screening
apparatus for separating grain from the graff to produce cleaned grain and
millings, and separate
outlets for the cleaned grain and millings. The cleaning mill includes a
receiving unit for the
3o graff for feeding the graff to the entrance of the graff cleaning mill, the
receiving unit being sized
to permit a graff delivery vehicle to drive into the receiving unit to
transfer an entire vehicle load
of graff to the receiving unit by a direct dumping operation of the entire
vehicle load.
CA 02311261 2003-03-07
3a
By the term "stationary cleaning mill" we mean a mill that is intended to be
operated at a
fixed location during the cleaning operation rather than being operated on the
move. The mill
may, however, be transportable from one location to another when not in use.
In another aspect, the invention provides a stationary cleaning mill for
graff, comprising
an entrance (usually located at an elevated position) for the graff, screening
apparatus for
separating grain from the graff to produce cleaned grain and millings, and
separate outlets for the
cleaned
CA 02311261 2000-06-09
grain and millings. The cleaning mill includes a material-conveying fan at the
outlet for the
millings, the material-conveying fan impacting the millings to cause at least
partial crushing or
breaking of weed seeds in the millings, removing the millings from the
cleaning mill, and
propelling the millings through the outlet for the millings.
According to yet another aspect of the invention, there is provided a mobile
harvesting
unit for harvesting graff, including a wheeled harvester body and a harvesting
header at the front
of the harvester body for cutting a crop from a field area, the harvester body
containing a
threshing unit for the cut crop for separating stalks from graff, a discharge
for discharging
separated stalks back to the field area, and a storage tank for storage of the
separated graff. The
harvesting unit includes an elongated hitching arm having opposite lateral
ends for connection at
one end to the harvester body and at an opposite end to a rear portion of a
propulsion device, the
hitching arm having a rdised section intermediate the opposite ends passing
over and clear of the
harvesting header.
According to yet another aspect of the invention, there is provided a hitching
arm for a
graff harvester, comprising a rigid elongated element having two opposite ends
for connection,
respectively, to the graff harvester and to a propulsion device. The arm has
upwardly extending
sections extending from each opposite end towards a centre of the hitching
arm, and an elevated
centre section.
According to still another aspect of the invention, there is provided a
receiving unit for
graff, for feeding graff to an elevated entrance of a graff cleaning mill,
including a receptacle for
graff and a conveyor for raising graff from the receptacle to the elevated
entrance. The receptacle
is sized to permit a graff delivery vehicle to drive into the receptacle and
to deposit an entire
vehicle load of graff into the receptacle by a direct dumping operation.
Preferably, the invention may provide a method of harvesting and cleaning a
plant crop,
wherein the crop is cut from a field area and threshed in a mobile harvesting
unit to produce
stalks that are returned to the field area and graff, a mixture of threshed
grain kernels, chaff and
weed seeds, which is collected within the harvesting unit, the collected graff
is transferred to a
vehicle when the harvesting unit is full, the graff is transported by the
vehicle to a cleaning mill
located in a yard area remote from the field area, and the graff is cleaned
automatically by the
cleaning mill to produce a cleaned grain product and a mixture of chaff and
weed seeds, wherein
a capacity of the harvesting unit to hold graff is made the same as or smaller
than a capacity of a
vehicle used for the delivery, the rate of cleaning of the graff by the
cleaning mill is made the
same as or higher than a rate of graff output from the field area averaged
over several cycles of
filling and emptying the harvesting unit and transfer to the vehicle, and the
number and speed of
CA 02311261 2000-06-09
operation of the vehicles is made high enough to avoid substantial waiting
periods between filling
of the harvesting unit with graff and transfer of the collected graffto the
vehicle.
Preferably, the capacity of the harvesting unit is substantially the same as
the capacity of
the vehicle, and a single vehicle is provided for transporting the graf~
It is also preferable that the capacity of the cleaning mill to hold and
process graff is no
less than the capacity of the vehicle to transport graff from the field area
to the cleaning mill, and
the rate of cleaning of the graff by the cleaning mill is about the same as
the rate of graff output
from the field area.
In another preferred form, the invention provides a system of harvesting and
cleaning a
plant crop, which comprises: a harvesting unit for cutting a crop from a field
area and threshing
the cut crop to produce stalks that are returned to the field area and
"graft', a mixture of grain,
chaff and weed seeds, which is collected within the harvesting unit, a vehicle
for receiving
collected graff from the harvester unit when the harvesting unit is full, and
for transporting the
graff to a cleaning mill; and a cleaning mill located in a yard area remote
from the field area, for
cleaning the graff to produce a cleaned grain product and "millings", a
mixture of chaff and weed
seeds, wherein a capacity of the harvesting unit to hold graff is made the
same as or smaller than
a capacity of a vehicle used for the delivery, a rate of cleaning of the graff
by the cleaning mill is
made the same as or higher than a rate of graff output from the field area
averaged over several
cycles of filling and emptying the harvesting unit and transfer to the
vehicle, and a number and
speed of operation of the vehicles is made high enough to avoid substantial
waiting periods
between filling of the harvesting unit with graff and transfer of the
collected graff to the vehicle.
In another preferred aspect, the invention relates to a mobile harvesting unit
for
harvesting graff, comprising a harvesting header (e.g. a direct-cut or swath
pick-up type) at a
front of the harvesting unit for removing a crop from a field area, a
threshing unit for separating
stalks from a mixture graff, a mixture of grain, chaff and weed seeds, a
storage tank for storage of
the separated graff, and a hitching arm for connection to a rear portion of a
propulsion device, the
hitching arm being of inverted generally U-shape to allow attachment at
opposite ends of the arm
to the unit and the propulsion device while extending over the harvesting
header.
In the harvesting unit of this kind, the hitching arm preferably supports and
guides a
mechanical driveling for transferring mechanical power from the propulsion
device to the
harvesting unit, the driveline including a plurality of rotary shafts joined
by constant velocity
joints or U joints to allow the driveline to adapt to changes of direction of
the hitching arm. The
hitching arm may also be used for guiding and protecting hydraulic tubes for
conveying hydraulic
CA 02311261 2000-06-09
fluid under pressure from the propulsion device to the harvesting unit. These
tubes may pass
through an interior channel in the hitching arm.
1n another preferred aspect, the invention relates to a mobile harvesting unit
for
harvesting graff, comprising a cutting head, a threshing unit for separating
stalks from graff, a
mixture of grain, chaff and weed seeds, a storage tank positioned above the
threshing unit for
temporarily storing graff, an auger bed for transporting graff to collection
areas on opposite
lateral sides of the unit, and a pair of graff elevators, one on each side of
the storage tank, for
simultaneously removing graff from the collection areas of the auger bed and
for delivering
removed graff to a top of the storage tank.
Further, the invention in another preferred aspect relates to a cleaning mill
for graff,
comprising a receiving unit for graff sized to allow a graff transportation
vehicle to drive at least
partially therein for dumping a load of graff, a graff conveyor for feeding
graff into the mill as a
moving matted layer of approximately constant thickness (preferably in the
range of 1.5 to 3
inches), and elevators for tilting the receiving unit, following removal of
the vehicle, to cause the
load of graff to slide to the graff conveyor.
Further, in another preferred aspect, the invention relate to a cleaning mill
for graff,
comprising an aspirator for blowing air through a falling matted layer of
graff to remove chaff
and light materials leaving aspirated graff containing grain kernels and heavy
materials, a
centrifugal separator for removing the chaff from the air after passing
through the curtain of graff,
a fan and ductwork for recirculating air continually through the curtain of
graff and through the
separator, a screening unit for separating grain from remaining materials from
the aspirated graff,
an outlet for the separated grain, a mill for milling the remaining materials
to produce millings,
ductwork for circulating the millings to the centrifugal separator, an outlet
device for removing
solids from the centrifugal separator for discharge from the mill.
It will be appreciated that, in the following discussion, the reference to
"grain kernels" or
"grain" as the desired product of the harvesting operation should be taken to
include the grain
kernels or seeds of all crops that are harvestable by conventional combine
harvesters, not merely
wheat. Such products include, for example, oats, barley, peas, lentils, rice,
soybeans, mustard
seed, canola, rapeseed, etc. The harvesting system of the present invention
can be operated with
all such crops.
Moreover, while the grain kernels are separated from the graff to leave a
mixture of chaff,
weed seeds and other materials, referred to as millings, the components of the
millings may
themselves, if desired, be separated either during the cleaning of the grain
in the cleaning mill, or
subsequently. Separate outlets may be provided for the separate components of
the millings.
CA 02311261 2000-06-09
_- 7
a _ Thus, while the claims of this application may refer to an outlet for
millings, there may in practice
be two or more outlets for various components of the millings, and the term
used in the claims is
intended to cover this eventuality.
It will also be understood that the millings may contain additional elements
such as
unthreshed heads, pieces of straw, dust, leaves, and other harvesting residues
and debris, and so
the term should not be limited merely to a mixture of weed seeds and chaff.
In the following description, numerical values are often expressed both in
metric units
and in non-metric units (the latter being shown in brackets). In the event of
any discrepancy, the
values expressed in non-metric units should be considered correct.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. I is a schematic sketch illustrating the overall harvesting method
according to a
preferred form of the present invention;
Fig. 2 is a perspective view of a preferred embodiment of a harvesting unit
suitable for
use in the method of the invention;
Fig. 3 is side view, with internal elements visualized, of the preferred
harvesting unit of
Fig. 2;
Fig. 3A is a view similar to Fig. 3, showing the threshing mechanism and graff
collection
area in isolation;
Fig. 4 is a side view in cross-section of a hitching arm of the harvesting
unit of Figs. 2
and 3;
Fig. 5 is a top plan view of a harvesting unit according to Fig. 2 and Fig. 3
showing the
method of attachment to a conventional tractor;
Fig. 6 is a top plan view of an auger bed, shown in isolation from other
equipment, as
used in the harvesting unit of Fig. 2 and Fig. 3;
Fig. 7A, 7B, 7C and 7D are simplified cross-sectional view of the harvesting
unit of Fig.
2 and Fig. 3, showing how graff is lifted into and moved within the graff
storage tank;
Fig. 8 is a side elevation of an alternative preferred embodiments of the
harvesting unit
and hitching arm of the present invention attached to a conventional tractor;
Fig. 8A is an enlarged view, partly in cross-section, of a joint in a power
transmission line
carried by the hitching arm of Fig. 8;
Fig. 8B is a top plan view of the harvester of Fig. 8 showing a horizontal
section
immediately beneath the graff storage tank and straw walkers, showing the
augers used to move
the graff and the direction of graff flow (indicated by arrows);
CA 02311261 2000-06-09
' , Fig. 8C is a top plan view of the harvesting unit of Fig. 8 looking down
upon the graff
collection tank and showing (by arrows) the direction of movement of graff
through the tank and
removal chute;
Fig. 9 is a perspective view of a preferred embodiment of a cleaning mill
suitable for use
in the method illustrated in Fig. I;
Fig. I 0 is a perspective view on an enlarged scale of a screening unit
forming part of the
cleaning mill of Fig. 9;
Fig. 1 I is a side elevation of a graff receiving unit and graff conveyor, on
an enlarged
scale, forming part of the cleaning mill of Fig. 9, the receiving unit being
in the down position
ready to receive a graff transportation vehicle;
Fig. 12 is a view similar to Fig. 11, but showing the receiving unit in the
raised position
for feeding graff to the graff conveyor;
Fig. 13A is a side elevational view of the aspirator, fan and centrifugal
separator forming
a closed graff cleaning circuit and forming part of the apparatus of Fig. 9;
Fig. 13B is a view similar to that of Fig. 13A from the other side;
Fig. 13C is a perspective view of a reel used in the apparatus of Figs. 13A
and Fig. 13B;
Fig. 13D is a sketch showing a millings discharge pipe having a cyclone
deceleration unit
at its free end; and
Fig. 14 is a side elevation of a cleaning mill, graff receiving unit and graff
conveyor
according to a second preferred embodiment of the present invention showing
the graff receiving
unit in an upright position containing a transported load of graff; and
Fig. 15 is a top plan view of the cleaning mill (the graff receiving unit and
graff conveyor
having been omitted) according to Fig. 14.
BEST MODES FOR CARRYING OUT THE INVENTION
Harvesting Method
One of the objectives underlying the present invention is to improve the
efficiency of the
graff harvesting and cleaning system described in the McLeod patents mentioned
above, as well
as providing a further alternative to the use of conventional combine
harvesters for harvesting
grain. The inventors named in the present application has found that one way
of achieving this is
to ensure that components of the system are designed so that harvested
material (the graff) flows
constantly and efficiently through the system without avoidable delays. This
has the advantage
CA 02311261 2000-06-09
not only of maximizing operation efficiency, but also of avoiding the need for
temporary storage
of graff and thus avoiding the problems caused by the poor flow properties of
graff.
As in the McLeod patents, the components of the system of the present
invention
comprise: (1) a mobile harvesting unit for harvesting the crop, i.e. for
collecting graffand
returning stalks to the field; (2) a cleaning mill for separating grain
kernels from the remainder of
the graff, and preferably for crushing and/or shredding the remainder of the
graff to compact it
and to reduce the viability of the weed seeds; and (3) one or more vehicles
(normally trucks
provided with open truck boxes coverable by a tarpaulin or the like to prevent
loss of graff
through blowing) for transporting harvested graff from the harvesting unit to
the cleaning mill.
As already noted, a particular problem encountered in dealing with graff is
that, while it is
not particularly heavy, it is very bulky compared to the cleaned grain product
delivered from a
conventional combine harvester (the amount of graff collected from a given
crop area may be as
much as four times higher in terms of volume than the amount of grain
collected by a combine
harvester from the same crop area). Moreover, unlike grain, graff does not
flow easily; it tends to
pack, clump, bridge, rat-hole and bind, making its transfer within and between
mechanical
equipment very difficult.
In view of the problem of excessive bulk, one might think that a solution
would be to
provide a harvesting unit with an internal graff collection container (storage
tank) that is as large
as possible to avoid the need for frequent stops to discharge the collected
graff. However, if this
is done, the volume of the collected graff may exceed the capacity of the
transport vehicle (truck)
used to transport the graffto the cleaning mill, resulting in delays and/or
the need for additional
vehicles. Similarly, if the amount of graff delivered to the cleaning mill at
one time is too large,
there may be a build-up or overflow of collected unprocessed graff, ultimately
resulting in a
temporary storage or termination of harvesting to allow for the graff build-up
to be processed.
A preferred solution to this problem is to ensure that the capacities of the
various
components (harvesting unit, vehicle, cleaning mill) are matched to allow an
even and continuous
flow of graff through the system to avoid the need for temporary storage of
the graff before it is
processed. Consequently, the graff holding capacity of the harvesting unit
should preferably be
as large as possible, but no larger than the capacity of a vehicle used to
transport the graff to the
cleaning mill, and the throughput of the cleaning mill should preferably be
such that it may
handle a volume of graff at least as great as the graff holding capacity of a
vehicle used to
transport the graff in the vehicle turnaround time (the time between
successive deliveries of graff
from the harvesting unit to the cleaning mill).
CA 02311261 2000-06-09
-' 10
- . This is illustrated schematically in Fig. 1 of the accompanying drawings.
The drawing is
a plan view representing in a very general way a field area 10, a road (or
track) system I 1 and a
yard area 12. A harvesting unit 15 (graff harvester), pulled by a conventional
tractor 16, harvests
a crop from the field area 10, returns stalks to the land and collects graff
(threshed grain kernels,
chaff, weed seeds, small bits of straw, etc.) inside the harvesting unit 15 in
an internal container
(storage tank) until the container is full. The harvesting unit 15 then stops
and unloads the
collected graff into a graff transport vehicle 17 (generally a standard dump
truck with an open-
topped truck box and an openable rear silage gate) which, when full,
transports the collected graff
I 8 to a cleaning mill 20 located in the yard area 12. Here, the vehicle 17
dumps the graff 18
through the entire rear gate into a graff receiving unit 21 of the cleaning
mill 20 and returns (as
shown at 17') to the field area to repeat the cycle. The capacity of the graff
receiving unit 21
should be at least as large as the carrying capacity of the vehicle 17 so that
the vehicle may
unload fully immediately upon arrival at the cleaning mill so that it is not
delayed. If the cleaning
mill 20 is intended to process the graff from several harvester units at the
same time, then the
capacity of the cleaning mill must be increased correspondingly. The graff 18
deposited in the
receiving unit 21 of the cleaning mill passes immediately through the cleaning
mill and is
separated into cleaned grain 25 and millings 26 (a mixture of smaller grain
kernels, weed seeds,
chaff, and small bits of straw, etc.) that have been subjected to milling.
The harvesting unit 15 has an internal graff storage capacity that should be
approximately
2o the same as, or at least no larger than, the capacity of the vehicle 17 so
that the internal container
of the harvesting unit, when full, may be emptied completely into the truck
box of a single
vehicle 17. This may be done by stopping the harvesting unit at a waiting
truck, or by emptying
the harvesting unit into a moving truck as both continue to move (with or
without further
harvesting). More than one vehicle may be provided, depending on the distance
of the field area
10 from the yard area 12, and the rate of operation of the harvesting unit 15.
Ideally, there should
be a waiting vehicle 17 whenever the harvesting unit 1 S is filled and is
consequently required to
stop. For greatest economy of operation, only a single vehicle 17 is required
to operate the
method continuously, which means that the time required to fill the container
of the harvesting
unit with harvested graff should be approximately the same as the time for
transport, dumping
and return of the single vehicle 17.
This may be expressed in another way. Although the harvesting unit I S
harvests (collects
and delivers) the graff on a batch basis, it will, on average, have a rate of
graff delivery that can
be expressed in units of weight or volume per unit time. The rate of graff
harvesting by the
harvesting unit 15 should, for the most effective and efficient operation, be
essentially the same
CA 02311261 2000-06-09
as the average rate of transport of the graff by the vehicle 17 from the field
area 10 to the yard
area 12.
At the yard area 12, the cleaning mill 20 is capable of processing graff at a
certain speed
when operating continuously. This can also be expressed in terms of units of
weight or volume
per unit time. For efficient and effective operation, the speed of processing
of the graff should be
no slower than the average rate of graff delivery by the vehicle 17, and no
slower than the rate of
graff harvesting by the harvesting unit 15. This ensures that the various
pieces of equipment
(harvesting unit, cleaning mill and delivery trucks) all work as an integrated
system.
Ideally, therefore, in this system, the rate limiting step should be the
harvesting of the
crop by the harvesting unit 15. That is to say, the crop should be collected,
transported and
processed as quickly as the crop can be cut and threshed (stalks removed) by
the harvesting unit
15. This means that, if the field area 10 is physically close to the yard area
12, it may be adequate
to have a single vehicle 17 because it may have the time to transport, dump
and return between
each completion of a filling cycle of the harvesting unit. This is the ideal
situation. Obviously,
from time to time, the ideal arrangement will break down, but the system
should be designed to
allow such efficient operation to be the norm. As the distance from the field
area to the yard area
increases, more vehicles may be provided. However, as the separation of the
field area from the
yard area increases, there will come a time when it is too expensive or
impossible to provide
enough vehicles 17 to maintain the required minimum rate of collection and
delivery of the graff.
2o Often this physical separation limit is found to be in the order of 6 km.
On the other hand, the
physical separation of the field area 10 and the yard area 12 should have no
significant effect on
the speed of throughput of the cleaning mill because this should always be the
same as, or higher
than, the rate of crop cutting and graff collection by the harvesting unit, or
several harvesting
units if the mill is intended to service several such units. The relative
capacities and throughputs
of the harvesting unit 15, the vehicles) 17 and the mill 20 should be designed
and utilized to
ensure that this is so. Trucks of the type normally employed for hauling grain
and the like usually
have a capacity of about 21 m3 (750 cubic feet), so the storage capacity of
the harvesting unit 15
and the capacity of the graff receiving unit 21 should preferably be about the
same.
While this optional organization of the entire system is desirable, it would
still provide
problems if carried out with equipment basically as shown in the McLeod
patents. The reason for
this is best described with reference to Fig. 7 of US Patent 5,795,222, which
is one of the
McLeod patents. This drawing shows a grain truck 20 having raised sides 21
discharging graff
into a hopper 23 through a small discharge port provided at the lower central
part of the read
raised side of the truck. The hopper is then emptied by a large grain auger 22
into one of several
CA 02311261 2000-06-09
.' 12
surge storage bins 24 provided for temporary storage. A further auger 26 then
transfers graff at a
constant rate from one of the bins 24 to the upper entrance 54 of the yard
plant (cleaning mill) 48.
However, because of the poor flow properties of the graff, it is difficult to
discharge the material
from the truck through the small discharge port in the rear tailgate of the
truck, and difficult to get
the graff to flow from the lower conical ends of the surge storage bins. This
creates inefficiencies
and difficulties that can cause delays in the cleaning of the graff while
attempts are made to cause
the graff to flow properly again.
Solutions to this problem, at least in its most preferred forms of the present
invention,
make use of ways of causing graff to flow that have been devised by the
inventors. The inventors
have observed that graff can be caused to flow without difficulty in the
following ways:
1 ) Graff can be caused to slide bodily or tumble down a slope (or chute)
inclined at a
suitable downward angle, provided that it is not impeded in any way, e.g. by
inwardly tapering or
inwardly stepped walls provided at the lateral sides of the sloped surface or
chute. This avoids
the problem encountered when a delivery truck of the type shown in the McLeod
patents is
IS provided, i.e. a truck having a small opening or delivery port provided in
the tailgate (which is
typical of grain delivery trucks). The tailgate impedes the sliding or
tumbling action of the graff
and provides a "choke point" that impedes smooth graff flow.
2) A quantity of graff can be removed from the bottom of a pile of graff, or a
container (e.g. a silo) full of graff, provided that essentially the entire
lowermost layer (or an
2o inner layer) of the graff is removed all at one time, rather than just a
part of the graff from the
lowermost layer (or any inner layer) as has been done conventionally. This can
be achieved by
moving a conveyor surface or a series of elongated transverse elements (rakes
or slats) beneath
the pile or contained body of graff, while preferably maintaining the
remainder of the body of
graff essentially stationary in some way. If essentially the entire lowermost
layer of the graff is
25 removed, the remainder of the graff can move downwardly without binding or
bridging. If it is
desirable to prevent the remainder of the graff from moving as the lowermost
layer is withdrawn
(which is the case if a constant supply of graff is to be delivered to a piece
of equipment, such as
the cleaning mill), the remainder of the graff may be confined within a
container or behind a
retaining wall, or the body of graff may be supported on an upwardly sloping
surface so that the
30 weight of the body of graff prevents it from following the movement of the
removed layer.
3) Graff can be caused or ''encouraged" to flow bodily from one point A, e.g.
a point
of delivery within a container, to another point B by moving an upper layer of
a body of graff
from point A towards point B. This is best used in conjunction with 2), i.e.
the moving of a lower
layer of material from point A to point B (without of course attempting to
prevent the movement
CA 02311261 2000-06-09
13
of the body of graff as is done in some forms of 2). This can be done, for
example, by providing
augers at an upper level of the body of graff, and is particularly useful
within a graff harvesting
unit where graff is collected a the front of a container and has to be moved
to an outlet region or
well at the back of the container.
4) Graff can be conveyed in a current of air of suitable volume and velocity,
but this
may cause some separation of the components of the graff. However, such
separation is desired
in certain parts of the system, e.g. in the cleaning mill, so movement of
graff in this way tends to
be confined to such system parts.
5) Graff can, of course, be moved bodily as a single mass, e.g. on a
horizontal
moving surface (e.g. a conveyor). This is useful, for example, for emptying
graff from a rear well
of a harvester unit, or the like.
In the present invention, these concepts may be used singly or, more
preferably, in
combination.
A practical application of these observations has already been suggested in
Fig. 1 of the
present application in that the cleaning mill 20 is provided with an integral
graff receiving unit
21. This is sized to receive the entire contents of a delivery truck, which
can consequently dump
its entire load of graff through its open tailgate (which may be hinged at the
top or bottom to
allow it to be swung out of the way). As will be apparent from the following
description of
preferred versions of the cleaning mill described below, the receiving unit is
specially designed to
raise the deposited graff to an elevated entrance of the cleaning mill without
encountering
problems caused by the poor flow characteristics of the graff.
Thus, an important aspect of the present invention is to avoid the need for
temporary
storage of the graff by allowing for a full load of graff from at least one
delivery vehicle to be
delivered at once to a graff receiving unit of a cleaning mill, which unit can
then deliver a regular
supply of the graff to an elevated input opening of a cleaning mill. If this
is done, and if the rate
of cleaning of the graff in the cleaning mill is sufficiently rapid, the graff
may be transferred from
the harvesting unit, directly to the delivery vehicle and then directly to the
cleaning mill without
any intermediate storage of any kind, thus avoiding problems encountered with
the use of
conventional storage silos and the like. Temporary storage may of course be
provided by the
delivery vehicles themselves, in that if the harvesting rate were to exceed
the cleaning rate
temporarily, the temporary excess of graff could be held in a sufficient
number of delivery
vehicles, if needed, and provided such vehicles were available. Clearly this
is to be avoided if
possible, but could provide a temporary solution to overflow problems.
CA 02311261 2000-06-09
_' 14
Another important aspect involves the design of the harvesting unit to make
best use of
the principles of graff flow described above.
Yet another important aspect of the invention involves the design of the
cleaning mill that
makes efficient use of movement and separation of graff, at least in part by
the use of air currents.
Yet another important aspect of the invention involves the design of the
harvester unit
that allows it to be towed by a conventional vehicle, e.g. a tractor. While
this has nothing to do
with the flow properties of graff itself, it is important for the overall
economy of the present
invention as such vehicles tend to be less expensive to manufacture and to
operate. A special
hitching arm has been developed for this purpose.
With these basic concepts in mind, a description of preferred embodiments of
the novel
components of the graff harvesting system of the invention will be provided
below.
Improved Graff Harvesting Harvesting Unit
For even greater efficiency and effectiveness of harvesting, improved
harvesting units
have been developed according to the present invention. These harvesting units
may be used in
the harvesting method indicated above or in other harvesting methods, e.g. as
disclosed in US
Patent 5,873,226.
Various graff harvesting harvesting units are disclosed in US Patent
5,794,423. These
harvesting units are effective, but they are expensive to manufacture and can
be cumbersome and
difficult to operate. Moreover, because of the difficulties in making graff
flow evenly, the
material flow through the known harvesting units may not always be optimum.
The preferred
harvesting unit of the present invention overcomes these problems to a
desirable extent.
Farmers in recent years have become used to self propelled harvesting units,
such as
conventional combine harvesters. Several of the harvesting units disclosed in
US Patent
5,794,423 are of the self propelled kind. However, the required motor, driving
controls and
steering mechanisms add considerably to the cost of such vehicles. US Patent
5,794,423 also
discloses non-powered (pull-type) harvesting units (see, for example, Figs. 4
to I O of the patent),
but these are of the "wrap-around" kind, i.e. the harvesting header is
positioned in front of a
propulsion unit (tractor), while the remainder of the harvesting unit is
positioned to the side or
rear of the propulsion unit. This leads to a mechanically complicated,
cumbersome and
expensive designs.
The harvesting unit of the present invention is based in part on the concept
of providing a
pull-type unit for cost-reduction (most farmers already have their own
tractors or other suitable
propulsion units) while avoiding the complexity of the wrap-around design by
towing the
CA 02311261 2000-06-09
_' 15
harvesting unit at the rear of the propulsion unit. However, this creates a
problem in that, if the
harvesting unit is towed behind a tractor, there is difficulty in providing a
suitable means of
attachment between the two since the harvesting header (particularly a direct-
cut header) is
necessarily positioned immediately behind the tractor hitch point, making a
conventional tow bar
impossible to use and blocking access to the tractor's mechanical and
hydraulic power supplies.
The header also has a cutter bar that must be raised, and this imposes a
further constraint on any
towing system. This difficulty has been overcome according to the present
invention by
providing a harvesting unit having a novel hitching arm.
A first preferred embodiment of the improved harvesting unit 15 is shown in
perspective
view in Fig. 2 of the accompanying drawings. As shown, the harvesting unit 15
comprises a
harvesting header 30, that may be of either the direct-cut type (e.g. a
conventional header,
normally 7.3 to 9m (24 to 30 feet wide)) or a swath pick-up header (normally
4.25 m (14 feet)
wide). A crop feeder housing 31, e.g. a chain feeder, feeds the cut crop
rearwardly to the
harvester body containing the unit's internal threshing mechanism, described
in more detail later,
where the cut crop is separated into stalks (which are returned to the field
as straw) and graff (a
mixture of grain, chaff and weed seeds, etc.). The body of the harvester unit
also contains a graff
holding container or tank 33 to which graff is transferred after being
collected from the threshing
mechanism. When the tank 33 is full, the unit 15 is stopped (or unloaded on-
the-move), and the
graff is transferred to a transport vehicle 17 (not shown in this view, but
see Fig. 1) via an
unloading auger 34. The harvesting unit 15 is pulled on unpowered wheels 32 by
a conventional
tractor 16 (not shown in this view, but see Figs. 1 and 3) via a hitching arm
35 that not only acts
as a tow bar, but also supplies mechanical and hydraulic or pneumatic power to
the harvesting
unit 15 from the tractor and provides a steering function.
In the harvesting unit of the invention, at least in preferred forms, several
factors combine
to make the use of the illustrated hitching arm possible. Unlike a regular
combine harvester, the
harvesting unit does not contain a grain cleaning apparatus (because it is
intended to harvest
graff), which means that the threshing cylinder 30 may be positioned closer to
the ground. The
grain feeder housing 31 from the cutter head to the threshing cylinder may
also be made quite
short as a result (e.g. about 1.2 m (four feet)), and this allows the
harvester to be located closer to
the tractor, and means that the cutter head does not have to be raised very
much in the stowed
condition. In consequence, the hitching arm 35 may be quite short and the
cutter head 30 easily
fits within the "crook" of the hitching arm in the raised condition.
In a first embodiment, the hitching arm 35 has a closed-in hollow tubular
design and, in
side view, as best shown in Fig. 3, it has a centrally-raised shape (referred
to for convenience in
CA 02311261 2000-06-09
16
the following as an "inverted U-shape", although it is realized that this is a
very loose description
- a more accurate description would be that the hitching arm is elongate with
two opposite ends;
the arm ramps or rises upwardly from each end towards the centre of the arm,
and the arm has a
short, elevated, generally horizontal section between the ramped or raised
sections at in the
middle of the arm). The inverted U-shape allows the crook C (upward bend) of
the hitching arm
to extend over the top of the harvesting header 30, with enough clearance to
allow the header to
be raised to the elevated (stowed) position shown in Fig. 3. This generally
means that the crook
C, at its highest point, must be elevated by a distance of at least 3 m (10
feet) from the ground.
The length of the hitching arm 35 must also be suitable to prevent it fouling
the harvesting header
30 during normal harvesting, even when the harvesting unit 15 is steered out
of direct alignment
with the tractor 16 (as will be explained later). This usually means that the
hitching arm must
project horizontally by at least about 6.5 m (21 feet). However, the hitching
arm should
preferably be no longer than necessary to achieve this objective in order to
minimize turning
moments (that may overwhelm the steering mechanism of the tractor if they
become too great)
when the hitching arm is moved to one side of the tractor or the other. For
comparison, a hitch
that would have to be used for a pull-type combine harvester would have to be
longer and
stronger, i.e. at least 10 m (33 feet) in length, because of the added weight
of the combine. This
makes it extremely difficult or impossible to control side forces in a non-
aligned cutting
operation. The maneuverability would therefore be lost with such a machine.
Since the hitching arm must pull quite a heavy load (the harvesting unit plus
harvested
graff), and since it is of inverted approximately U-shape as shown, forces
encountered during
harvesting will tend to pull the ends 37 and 38 of the hitching arm towards or
away from each
other. The hitching arm should therefore be made sufficiently strong and rigid
that significant
flexing of this kind is prevented. In the illustrated embodiment, the hitching
arm is made of three
main tubular elements of square cross-section, 36, 39 and 40, that are welded
together at their
interconnecting joints 41 and 42. A heavy gauge steel box construction is
suitable for this
purpose.
The hitching arm 35 is shown in isolation and in longitudinal cross-section in
Fig. 4. The
interior 44 of the hitching arm 35 forms an enclosed channel which may be
used, if desired, to
accommodate hydraulic and electrical lines (not shown) extending between the
tractor and the
harvesting unit. Generally, the hydraulic system includes three hydraulic
sets, one for pivoting
the header 30, one for turning the header, and the third for raising the
header. The hydraulic
cylinder 69 used for raising and lowering the harvester head is visible in
Fig. 3.
CA 02311261 2000-06-09
,' 17
The top edge of the arm is used for guiding a mechanical driveline 45 that
conveys rotary
motion from the tractor's mechanical drive to the harvesting unit where it is
used to drive the
harvesting header 30 and other components. The driveline consists of several
straight shafts 46,
47, 48, 49, 50 interconnected at their ends by means of constant velocity
joints 51, 52, 53, 54 and
55. Alternatively, the joints may be interlaced pairs of U joints. The ends of
the driveline may
also include constant velocity joints 56, 57 for connection to the mechanism
of the harvesting unit
and the tractor, respectively. Suitable bearings 58, 59, 60, 61, 62, 63, 64,
65 are provided on the
upper surface of the hitching arm to secure the driveline and to ensure that
the shafts rotate
smoothly. The constant velocity joints employed for this purpose are
preferably capable of
operating at angles up to 17° and of handling power transmission of up
to 150 kW (200 hp). The
use of constant velocity joints in the driveline not only means that the
driveline may follow the
inverted U-shape of the hitching arm 35, but also (because of the constant
velocity joints 56, 57 at
the extreme ends of the driveline) makes it possible that the hitch arm may be
moved out of direct
alignment with the tractor or the harvesting unit without damaging the
mechanism.
IS The driveline may be enclosed by an elongated cover 68 (shown in part in
Fig. 2) in the
form of an inverted channel section that fits over the upper edge of the
hitching arm.
As shown in Fig. 5, the hitching arm 35 is connected to a drawbar 70 of the
tractor 16 via
a conventional hitch 71. At the opposite end, the hitching arm 35 is connected
to the harvester
unit 15 via a "hydra-swing" hitch, which includes a pair of hydraulic
cylinders 72 and 73,
attached to the body of the harvester unit 15, that allow the hitching arm 35
to be kept in direct
alignment with the tractor 16, or moved to one side or the other, as shown.
This sideways
movement, which can be controlled by the operator of the tractor, allows the
tractor itself to
remain largely clear of the unharvested crop, and allows the harvesting unit
to be swung from one
side of the tractor to the other to facilitate back-and-forth harvesting of
the crop. On the other
hand, by positioning the harvesting unit directly in line with the tractor,
the overall width of the
equipment may be minimized (for passing through gates, and the like).
At its opposite end, the hitching arm 35 is connected to a frame element 74 of
the
harvesting unit for rotation about a generally vertical axis by means of a
vertical pivots 75 (see
Fig. 2). This allows the harvesting unit I S to remain in a forward-facing
direction, i.e. facing in
the same direction as the tractor, when moved to one side or the other out of
direct rearward
alignment with the tractor. The unpowered wheels 32 on which the harvesting
unit IS rides are
not steerable, and these wheels tend to keep the harvesting unit moving in the
same direction as
the tractor, even when the harvesting unit is moved to one side of the tractor
or the other.
CA 02311261 2000-06-09
18
As will be appreciated, the tractor 16 both powers and maneuvers the
harvesting unit 15.
For most applications, a standard 125 kW (165 horse power (hp)) tractor with a
95 kW (125 hp)
power take off (PTO) with three hydraulic couplings and suitable transmission
speeds will be
suitable to operate the harvesting unit 15.
As mentioned earlier, graff has proven to be an extremely difficult material
to handle
because it does not flow easily and because it is bulky and is produced in
large amounts. The
threshing and storage mechanism of the illustrated harvesting unit 15 is
intended to overcome the
difficulty of collecting and processing of graff.
As shown in Fig. 3, a chain-type crop feeder housing 31 conveys cut crop
material into
the interior of the harvesting unit 15 where the crop material encounters a
rotating threshing
cylinder 77 and a perforated concave 78 that, in conjunction with a rear
flanged beater roll 79,
subject the crop material to a severe threshing action. The separated grain,
chaff and weed seeds
(i.e. graff) fall through the perforated concave 78 and collect on an auger
bed 80, i.e. an inner flat
surface of the harvesting unit beneath the concave provided with several
narrow augers extending
IS front to back. The rest of the crop (stalks and remaining grain, etc.) is
then passed from the
cylinder 77 to an arrangement of straw walkers 82 which separate any remaining
graff from the
stalks. The graff separated in this way also falls onto the auger bed 80. In
the harvester unit 15
of the present invention, the feeder house 31 and straw walkers 82 may be made
considerably
shorter than those used in a conventional combine harvester (e.g. only 1.2 m
(4 feet) long for the
feeder house, and 1.8 m (6 feet) long for the straw walkers, as opposed to 3 m
( 10 feet) in a
combine harvester). This allows a more compact unit to be constructed, and the
short feeder
housing 31 allows the cutter bar of the header to fit under the crook C of the
hitching arm when in
the raised position. The threshing cylinder 77 is also very low, i.e. much
closer to the crop than
in conventional harvester designs. This allows the hitching arm 15 to be made
quite short (e.g. 6.5
m (21 feet)). The shorter length makes possible the unique shape of the
hitching arm and, in turn,
the unique shape makes it possible for the header to be raised and lowered
inside the crook of the
hitching arm.
The stalks are moved by the straw walkers to the rear of the harvesting unit
15, where
they are discharged onto the ground through a discharge opening 83 either as a
swath or as small
pieces formed when the stalks encounter an optional straw chopper/spreader 84.
As noted, the
graff separated by the straw walkers 82 falls through the straw walkers to the
bed 80 of the
harvesting unit.
The threshing and graff collection section of the harvester unit 15 is shown
in isolation
and increased size in Fig. 3A, in particular showing the various pulleys and
drive belts and
CA 02311261 2000-06-09
19
chains. The feeder of the feeder housing 31 is driven by feeder drive belt
180, and the cylinder
77 is driven by cylinder drive belt 181. Element 182 is a variable drive belt
driven by the main
pulley 183. The beater 79 is driven by a beater drive belt 184, and chopper 84
is driven by
chopper drive belt I 85. A secondary counter shaft 186 is driven by a
secondary shaft drive belt
187. The straw walkers 82 and auger bed 80 are driven by drive belt 188.
Element 189 is a
conveyor drive chain.
The auger bed 80 is shown in plan view of Fig. 6 in isolation from the other
elements of
the harvesting unit. The bed 80 slopes upwardly slightly from front to rear,
but the graff, as it
collects, is moved from below towards the rear of the bed by a set of several
rotating augers 84
provided just above the surface of the bed 80 and orientated in parallel from
the front of the bed
to the back and across the entire width of the bed. The graff is thus moved
bodily towards the
rear and encounters a transverse channel 85 containing a pair of coaxial cross
augers 86, 87 that
move the graff in opposite outward directions shown by arrows A and B towards
vertical paddle
elevators 88, 89. The storage tank 33 of the harvesting unit 15 (see Fig. 2)
is positioned
immediately above the collection bed 80 with enough vertical clearance for the
augers 84 and the
collected graff.
It is to be noted that, unlike many combine harvesters, the harvesting unit 15
lacks grain
cleaning apparatus and a mechanism for returning unthreshed heads to the
threshing cylinder.
This makes it possible to design a harvesting unit having a low profile
because the storage tank
33 may sit low over the auger bed 80, and it also results in a power saving
since material is not
being recirculated through the threshing mechanism. This further simplifies
the harvesting unit
of the present invention and makes it mechanically more reliable than a
conventional combine
harvester. In the apparatus of the invention, unthreshed heads are collected
with the graff and
become part of the millings, as described later.
As noted, the graff from the auger bed 80 is elevated to the height of the top
of the storage
tank 33 by a pair of paddle elevators 88 and 89 (see Fig. 3 and Fig. 6) for
the graff located at the
ends of the trough 85 on each side of the storage tank 33. Figures 7A, 7B, 7C
and 7C are
diagrams showing how the graff is raised into the tank 33, moved therein and
removed therefrom.
As shown in Figs. 7A and 7B, the graff elevators 88 arid 89 are positioned on
the outside of the
unit at their bottom ends and they extend upwardly and forwardly. The fact
that two elevators 88
and 89 are provided means that a large volume of graff from the collection bed
80 can be
accommodated at opposite sides of the tank, ensuring a regular flow of graff
from the collection
bed and into the storage tank at opposite sides, as shown by the arrows in
Fig. 7A. At a point
midway between the lower and upper ends, the elevators pass inside the tank
33, the entrance
CA 02311261 2000-06-09
areas being shown by shading in the drawing. The elevators discharge within
the tank 33 at the
upper front end. A pair of inwardly-directed augers 81 move the graff to the
middle of the tank
where another auger 90 is provided to help distribute the material to the
rear.
Fig. 7C shows the inside of the storage tank 33 at a point behind the
elevators 88, 89. The
5 tank has a unique shape designed to minimize problems caused by the poor
ability of graff to
flow. Various augers are provided to keep the graff moving as required within
the tank. The tank
is provided with a horizontal leveling auger 90 at the top to move the graff
backwards and to
prevent the formation of a central peak. A pair of rotating agitators 91, 92
are provided lower in
the tank to help prevent bridging within the body of graff. These agitators
are generally horizontal
10 but slope slightly upwardly towards the rear as shown in Fig. 3. At the
bottom of the tank 33, a
pair of delivery augers 94, 95 are provided to move the bulk of the graff
rearwards towards a well
96 (see Fig. 7D), i.e. a deeper section of the tank, formed at the rear of the
tank (see Fig. 3). The
lower wall 190 of the tank 33 is in the form of an inverted V so that the
graff is directed toward
transport augers 94 and 95. The well 96 forms the lowest collection point for
the graff and is thus
15 the last section of the tank to be emptied by an unloading auger 34, the
bottom end of which is
positioned at the bottom of the well 96. The auger 34 is actually made up of
two co-operating
augers, i.e. a vertical auger positioned in the well 96 that lifts the graff
out of the well 96 and a
horizontal auger that moves the graff to downward facing, preferably flexible,
delivery spout 97.
The well 96 forms a hopper which contains an exposed inclined section of
flighting 99 which
20 draws graff into the vertical, then horizontal, sections of the unloading
auger. The unloading
auger may be centered along the top of the storage tank 33 during harvesting,
and may be swung
to either side or to the rear for discharge of the graff into a waiting
vehicle 17. The unloading
augers are preferably of large diameter compared to those for unloading grain
from combine
harvesters. For example, the vertical auger may have a diameter of 41 cm ( 16
inches) or more
and the horizontal auger may have a diameter of 35.5 cm ( 14 inches) or more.
This allows for a
very rapid emptying of the tank, i.e. in the region of three minutes.
All of the various augers and agitators are driven by mechanical transmissions
(e.g. belts
and pulleys) taking power from the rotating shaft carried by the hitching arm
35.
The storage tank 33, which is preferably of approximately 21 m3 (750 cubic
feet) in
capacity (at least twice the size of the collection bin of the largest
conventional combine
harvester) and (as noted above) preferably has the same size as a truck box of
the vehicle 17, is
preferably provided with a particular shape that facilitates the storage and
movement of the graff.
As shown in Figs. 7A, 7B, 7C and 7D, the front wall 27 and lower parts of the
side walls 28, 29
of the tank slope inwardly from the top to the bottom. The angle of slope is
preferably made at
CA 02311261 2000-06-09
21
least 50° relative to the horizontal, so that the graff slides towards
the bottom of the tank and does
not become trapped at the base of the front and side walls in the form of
stagnant piles. This
feature makes use of the observed ability of graff to slide freely down a
slope having a suitable
angle of inclination. The sloping front wall 27 also allows the tank to clear
the hitching arm 35
and allows better weight distribution.
Although the storage tank 33 is designed to hold a substantial amount of
graff, the low
density of this material means that the tank does not have to be unusually
strong, so there is no
need for cross-bracing of the walls, or the like. In fact, the sculptured
(tapering) shape of the tank
increases its structural strength relative to a rectangular tank of the same
capacity.
The tank preferably has an open hatch 98 (Fig. 7C) on the top surface that may
be
covered when desired by a roll-back tarpaulin (not shown) or the like. This
allows access to the
interior of the tank for maintenance and to clear blockages.
It has been found advantageous to coat the inside of the tank 33 and auger
chutes with a
paint that forms a low friction surface in order to minimize binding of the
graff at the sides of the
tank. Preferably, the paint should provide a surface having a co-efficient of
friction of less than
about 0.45. Paint containing powdered graphite (e.g. paint sold by Acu Mech
Sys Enterprises
Ltd., under the trademark SLIP-PLATE~) is particularly effective in this way.
Fig. 8 is a side view of an alternative preferred embodiment of the harvesting
unit and
hitching arm of the present invention. In the description of this embodiment,
elements that are
identical or equivalent to those of the previous embodiment are identified by
the same reference
number with an added prime (e.g. 15 becomes 15').
It will first of all be noted from Fig. 8 that the hitching arm 35' is made up
of four
sections rather than three, these sections being 36', 39', 40' and an
additional vertical section 39a
at the tractor end of the hitching arm. The presence of the additional section
gives the arm a
greater approximation to the inverted U-shape mentioned earlier and provides
greater
"headroom" C' above the harvesting header 30' to allow the header to be raised
fully to the
inactive position, and also allows more room for the harvesting header in the
operational position
during swinging of the harvester unit 15' out from one side of the tractor 16'
or the other.
Depending on the materials of construction, this embodiment may encounter
slightly more
flexing during use than the hitching arm of the previous embodiment, the total
amount of flexing
being about 0.3 m (1 foot) between the opposite ends, and so this degree of
flexing must be
accommodated by the mechanical drive line 45'. This can best be done by
providing U joints at
the points where the drive line bends to follow the shape of the hitching arm,
and also by
providing slip joints (splined telescopic sections) within the driveline
itself to accommodate
CA 02311261 2000-06-09
22
lengthening and shortening actions of the line. As a alternative to using U
joints for this purpose,
it is also possible to use gearbox designs to achieve the required change of
angle. A suitable
gearbox design is shown in enlarged partial section in Fig. 8A, which shows
the driveline 45' at
the junction of arm sections 36' and 39'. The gearbox 801 consists of a
housing 802 containing
mutually-meshing rotatable beveled gears 803 and 804. The lowermost gear 804
is attached to
driveline section 47' for rotation therewith and the uppermost gear is
attached to driveline section
48' for rotation therewith. The angle at which the gears are mutually arranged
creates the change
of direction of the driveline 45' as it passes through the gearbox 801. A
small degree of angular
misalignment of the gears 803 and 804 is possible to accommodate flexing, and
more is permitted
by the presence of constant velocity joint 805 on one side of the gearbox and
a slip joint 806 on
the other side. The gearbox must be strong enough to transmit the power
provided to the
driveline 45' without distortion or overheating.
At the point of attachment of the hitching arm 35' to the tractor 16', a ball
joint 807 is
provided to allow sharp turns, and a gearbox 808 may be bolted to the tractor
body.
In this embodiment, the hitching arm 35' is attached to the harvesting unit
15' at pivot 75'
which is placed no more than about 1.2 m (4 feet) in front of the rotational
axis of the wheels 32'.
This positioning is important for two reasons. Firstly, the close proximity of
the pivot 75' to the
wheels means that easier turning of the harvesting unit by the hydraulic
cylinders 72' and 73'
(See Fig. 8C) can be achieved. Secondly, the centre of gravity of the
harvesting unit is slightly to
the front of the wheels when the unit is empty, but moves rearwardly of the
wheels as the unit is
filled during harvesting. This reduces the downward force on the hitching arm
and allows the
hitching arm to be of a lighter design than would otherwise be the case.
In this embodiment, the hydraulic lines from the tractor 16' to the harvesting
unit I S'
preferably follow the outside of the hitching arm 35' (rather than run through
the hollow interior)
for easier servicing, and the clearance of the cylinder can be adjusted from
inside the tractor
(along with all of the other hydraulic functions, preferably using a single-
handed joystick design).
The harvesting unit I S' of Fig. 8 differs from the harvesting unit I S
previously described
in several respects, as described in the following.
Firstly, instead of equipping the floor of the tank 33' with a series of
parallel augers, as in
the previous embodiment, in order to move the collected graff towards the rear
of the tank, a "live
floor" 810 is provided, i.e. an endless belt made up, for example, of mutually
spaced transverse
slats driven by chains. This makes use of the principal mentioned earlier that
graff may be
moved by moving or removing the entire lowermost layer of a body of the graff,
i.e. a lowermost
layer that extends completely across the width of the body of graff - in this
case substantially the
CA 02311261 2000-06-09
23
entire width of the tank 33'. In the previous embodiment, the intention was to
deliver the graff as
quickly as possible to a large rear well 96 positioned at the rear of the tank
33 from which the
graff can be augered out as shown in Fig. 7D. In this second embodiment, the
approach taken to
graff removal is different. Instead of the large well 96, the tank 33' is
provided with a shallow
transverse well or channel 96' enclosing a quite large (e.g. 50 to 60 cm (20
or 24 inches))
generally horizontal transverse auger 820 or alternatively a conveyor belt).
The live floor 810
slopes upwardly to the rear and thus the bulk of the body of collected graff
tends to remain
towards the front of the tank 33' and the movement of the live floor feeds a
constant supply of
graff into the channel 96' when the auger is operated, thus reducing the risk
that binding will take
place above the auger, or blockage of the channel 96' will occur.
The slats circulate around a plate 811 acting as a false floor of the tank and
the slats
themselves may be provided with flexible strips at the front to provide a
sweeping action over the
false floor. The chains 812 used to drive the slats (generally there are at
least 2 and preferably 3
parallel chains) provide an open structure that is self cleaning as it moves
around the false floor.
An alternative possibility would be to use a flexible (e.g. rubber) conveyor
belt instead of the
slats and chains, but material tends to build up underneath such arrangements,
so they are usable
but no preferred.
The transverse auger 820 in the channel 96' feeds a side-mounted hinged
enclosed
conveyor 815 or chute that is used to transfer the collected graff to an
adjacent vehicle (not
shown). The fact that the conveyor 815 is hinged means that it can be raised
or lowered to a point
just above the vehicle box. A conveyor is used rather than an auger to provide
bodily transport of
the graff supplied by the auger to prevent binding and blockage. The
arrangement also allows the
tank to be emptied quickly, e.g. within about 3 minutes or less.
A pair of augers 817 and 818 are provided at the top of the tank 33' in order
to level the
pile of graff (not shown) collected in the tank. These help to move the body
of collected graff
towards the rear of the tank. A sensor (not shown) is provided to indicate
when the tank 33' is
full so that graff does not overflow into and build up above the channel 96'
before the auger 820
can be operated to begin removal of the graff from the tank. Such overfilling
could promote
binding and blockage. The harvesting is interrupted when the sensor indicates
that the tank is full
and emptying commences, assuming that emptying is not being carried out
simultaneously with
harvesting (i.e. into a moving accompanying vehicle).
In this embodiment, the tank may be made larger than the previous embodiment
and the
slope of side walls 28' and 29' is made a minimum of 60°. The interior
of the tank is again
coated with low friction paint. The increased capacity may be obtained by
increasing the height
CA 02311261 2000-06-09
- 24
- of the unit to 4.25 m (14 feet) and increasing its length (e.g. by
approximately 1.5 m (5 feet)).
This may result in a tank 33' having a volume of approximately 31.8 m3 (1120
cubic feet). While
the tank 33' is generally made of sheet metal, such as steel, the tank may,
alternatively, be made
of plastic material as the graff load is light despite the large volume.
Cleaning Mill
To further improve the efficiency and effectiveness of the harvesting method,
an
improved cleaning mill 20 (often referred to as a yard plant) has been
produced.
The cleaning mill 20 is illustrated in perspective view in Fig. 9, from which
it can be seen
that the mill consists of several main parts, namely a drive-in graff
receiving unit 21 (which acts
as an open receptacle for the graff delivered by a vehicle) and graff conveyor
100, an aspirator
101 for removing chaff and light material from the graff, a millings
collection unit 102, a
screening unit 103, and a rolling mill 104. The aspirator 101 is powered by a
Written Pole motor
105, or alternatively a diesel motor, and the mill is controlled by a computer
module 106 (PLC).
Graff is delivered to the cleaning mill 20 directly from the field by a truck
17 (see Fig. 1).
In the past, attempts were made to pour the graff through a small door
positioned in the rear wall
or gate of the truck box in the same manner that grain is delivered to a grain
storage area.
However, as noted above, graff does not flow in the same way as grain, and
once deposited in a
2o pile, it is difficult to pick up and convey to the cleaning mill. To
overcome this problem, the
illustrated cleaning mill has a drive-in graff receiving unit 21 that allows a
truck to back directly
into the receptacle (as suggested by the tire tracks 107 shown in Fig. 9) and
to dump the graff by
unhooking the rear gate and raising the truck box (as illustrated in Fig. 1).
The graff receiving unit 21 is a grain receptacle in the form of a flat box
108 having a
slightly ramped bottom wall 109 and two longitudinal side walls 110, but no
end walls. The unit
is aligned with the more steeply upwardly ramped graff feeding apparatus or
conveyor 100
forming an inclined surface. Figs. 11 and 12 are side views showing the
receiving unit in a
receiving position (Fig. 1 ( ) awaiting a graff delivery, and in the upturned
operational position
(Fig. 12), in which the receiving unit acts as a chute so that graff is urged
onto the bottom end of
the graff conveyor 100. The tilting of the receiving unit is controlled by
hydraulic cylinders on
each side of the unit (although only one is shown in Figs. I I and 12).
In the case of the graff conveyor, the ramped surface 113 is provided with a
rotating drag
chain conveyor 112 that moves up the ramp and carries graff to the upper end
114. A rotating
delivery roller 115 at the upper end of the drag chain conveyor functions to
beat back graff
CA 02311261 2000-06-09
- 25
_ coming up the conveyor and equalize out the graff across the width of the
box (usually 10 feet
wide) so that only a 4 to 8 cm ( 1.5 inch to 3 inch) mat of graff proceeds to
the top 114 of the graff
receiving unit. The thickness of the mat is determined by the adjustable
distance from the drag
chain 112 to the roller 115. The roller is positioned a short distance (a few
centimetres) above the
upper end of the ramped surface 113, and is provided with projecting teeth 116
spaced along and
around the circumference of the roller. The delivery roller is rotated rapidly
by a motor (not
shown) and, as noted, feeds a "mat" or carpet of graff (i.e. a continuous
strip of even width and
thickness) into an upper entrance 117 of the aspirator unit 101 (see Fig. 9).
The graff conveyor
100 serves the purpose of lifting the graff from ground level to an elevated
position from which it
may be subjected to aspiration as it falls vertically back to ground level
within the cleaning mill.
A second function of the drag chain conveyor 112 is to meter (by changing the
speed of the
conveyor driven by a variable speed motor) the correct volume of graff
delivered to the top I 14
of the receiving unit and into the aspirator 101. Therefore, by varying the
speed of the conveyor
and by varying the distance between it and the roller 115, acceptable amounts
of graff can be
metered into the aspirator 101. It is important that the entire width of the
aspirator (3 m (10 feet)
for 91,000 litres (2,500 bushels) per hour) is matched to the width of the
receiving unit to
facilitate the continuous material flow capability of the entire machine.
The aspirator 101 is shown in greater detail and in isolation from the other
equipment in
Fig. 13A, 13B and 13C. The mat or carpet of graff passes through an entrance I
17 to the
aspirator unit and directly encounters an aspirator reel 300. The reel is
shown in isolation in Fig.
13C and it will be seen that a number of rubber cogs 301 (three inches in
height) are arranged
along the surface of the reel with a slight twist (preferably about
10°) in the axial direction to
facilitate entry of the graff into the aspirator. The rubber cogs 301 form an
air seal preventing air
under pressure in the aspirator 101 from escaping through the inlet 117. It
will be seen from Fig.
13A that there is no free space within the entrance 117 to allow graff to
settle and clog the
apparatus. Once graff passes through the entrance 117, it is immediately taken
up by the reel
which delivers it to the aspirator. As a stream 118 of graff falls vertically
through the aspirator, it
is subjected to a lateral airflow I 19 that impinges on one side (the front)
of the stream and passes
through to the other side carrying away chaff and other light materials. The
aspirator has six drop
zones defined by baffles 120. The air flow through each drop zone is
controlled by a manually
adjustable damper 121 at the drop zone's inlet. In each drop zone, the air
stream passes through
the falling graff.
The airflow 119 is created by a fan 122 which moves air along a lower duct 123
to a front
end of the aspirator, and then, after passing through the falling stream of
graff 118, returns the air
CA 02311261 2000-06-09
- 26
(and entrained chaff and light materials) through an upper duct 124. If too
much air is entering
into the front of the aspirator 101, air can be bled off directly into the
return air flow by a
manually operated gate 302. A centrifugal (cyclone) separator 125 removes the
chaff and light
materials from the air flow before the air returns to the fan 122. The
separated mixture of chaff
and light materials (referred to as "millings") is conveyed by a material
conveying fan 126 (see
Fig. 13B) to a conveying tube 127 and may be delivered to a suitable storage
pile, container, or
vehicle via a pipe 128 (see Fig. 13D) attached to the conveying tube 127. The
pipe 128 (which
may be as long as 15 to 21 m (50 to 70 feet)) has a small cyclone unit 129 at
its remote end acting
as a decelerator for the millings to prevent widespread distribution of this
light material, and
allowing it to collect into a pile 135.
The operation of the separator cyclone 125 is governed by the fan 122 (see
Fig. I 3A)
operating at a volume of about 340 m3 (12,000 cubic feet) per minute (for
91,000 litres (2,500
bushels) of graff per hour throughput). The fan forces air through the
aspirator 101 and along
duct 124 to the separator 125. The millings material contained in the airflow
upon reaching the
separator clings to the outer wall of the separator by centrifugal force and
moves to a final
discharge portal 303. The discharge through portal 303 is assisted by air
equalization tube 304
shown in Fig. 9 and by the discharge fan 126 shown in Fig. 13B. Within the
separator 125, clean
air in the middle of the unit is returned to the fan 122 by duct 305 shown in
Fig. 13B. The cleaned
air is driven by the fan 122 and returns to the aspirator 1 Ol via ducting 123
to a front side of the
aspirator. The ducting forms a closed loop for the air to recirculate between
the centrifugal
separator 125 and the aspirator 101. Dust build-up within the closed loop is
avoided by the
introduction of make-up air from the rolling mill 172 and screening unit 103.
The heavy material 130 (aspirated graff, which contains the grain and weed
seeds, etc.)
collects at the bottom of the aspirator 101 and is removed by a horizontal
cross auger 131, then
raised by paddle elevator 132 (see Fig. 9) to a drop tube 133, from which it
falls into the
screening unit 103 for separation into the desired cleaned grain product and
other a secondary
product comprising the remaining organic material.
The screening unit I 03 is shown in detail in the perspective view of Fig. 10.
The material
delivered from drop tube 133 falls into a split (bi-directional) leveling
auger 140 positioned at the
3o upper end of the screening unit which serves to distribute the material
evenly across the screens.
The unit consists of an open framework 141, retaining a number of downwardly
sloping
oscillating screens 142 arranged in two groups or "shoes." The opening size of
the screens
decreases from the uppermost to the lowermost screen, so that larger particles
are collected on the
upper screens and smaller particles descend to the lower screens. A separation
of the aspirated
CA 02311261 2000-06-09
27
graff based on particle size is thus obtained. The top shoe 143, contains
three scalping screens
144, 145 and 146, through which the grain passes and large material is
removed. The first screen
144 of this shoe directs stones and larger debris to a hopper 307 from which
it exits the machine.
The second and third screens, through which grain kernels drop, direct larger
crop material to a
trough 147. From the top shoe, the grain flow is divided and dropped onto two
screens on the
bottom shoe 148. The bottom shoe 148 contains two sets of three inclined,
oscillating sizing
screens. The grain passes over the screens while the "screenings" (weed seeds,
small kernels,
etc.) pass through and are gathered in a trough below the screen. The grain
then drops through a
plenum 160 with a cross-flow air stream where dust is removed from the grain
and conveyed
through a dust delivery tube 150. The grain falls into a cross-conveyor 161,
which delivers the
grain 25 into a hopper 165. From the hopper, the grain is conveyed to storage.
Screenings from the two top shoe screens and the six bottom shoe screens are
gathered in
troughs and routed via drop tubes to the bottom shoes screenings collection
trough. From this
trough, the screenings are delivered into a paddle elevator 170, which lifts
the screenings to a
drop tube 171, from which the screenings fall into an intake hopper of a
rolling mill 172 (see Fig.
9) where the screenings are rolled. From the bottom of the rolling mill 172,
air is drawn along
with the rolled screenings into a duct 308 connected to an intake 309 of the
cyclone separator
102. Within the separator 125, the rolled screenings from the mill 172 are re-
combined with the
light material from the aspirator 101 and the dust from the plenum 160 of the
screening unit 103
delivered via dust delivery tube 150.
As already noted, solids (millings) separated from the air by separator 125
are drawn by a
portion of the air through a duct 173 into a material-conveying fan 126 (Fig.
13B). The fan helps
to remove the millings and air from the separator 125 in a continuous manner
without disrupting
the centrifugal separation effect within the separator. This has proven to be
in improvement on
the usual air lock provided for removal of solids from a separator. The fan
125 also makes it
possible to project the millings a considerable distance from the machine via
conveying tube 127
and pipe 128 to the small cyclone decelerator 129. The millings, which consist
of just about all
of the organic matter from the graff other than the grain kernels are dropped
into a pile 135 for
storage. Weed seeds in this material have been passed through the rolling mill
172 and thus are
no longer viable (i.e. they are inert). Moreover, small screened grain kernels
are also crushed,
making them more digestible for cattle. The collected millings are therefore a
valuable product
that may be used as animal feed or for other purposes. Despite this rolling
step, only a single
material (other than the cleaned grain) is discharged from the mill because of
the recirculation of
rolled material to the intake of the separator unit where it is mixed with
light materials from the
CA 02311261 2000-06-09
- 28
_ aspirator. Of note is also the final air bath applied to the cleaned grain
just before it is discharged
from the mill. This air bath removes fine dust that is also recirculated to
the intake of the
separator 125.
Of course, if desired, the rolled material and/or the dust from the air bath
need not be
returned to the separator, but could be discharged independently merely by
rerouting the
indicated piping. The material from the screens (screenings) is by itself a
high protein feed
material.
A particular advantage of the cleaning mill is that, if desired, it can be
operated
automatically, essentially without an operator. Computer control ensures
normal operation of the
mill at all times.
An alternative embodiment of the cleaning mill is shown in Figs. 14 and 15. In
this
embodiment, the graff receiving unit 21' (which forms an open receptacle for
the graff) and the
graff conveyor 100' are essentially the same as in the previous embodiment and
allow graff to be
deposited as a full load from a truck by upending the truck box, dumping the
graff load, and
delivered in a constant stream to a laterally elongated upper inlet 117' of
the cleaning mill
without binding or blocking and without the need for intermediate storage.
However, upon
passing through the inlet I 17', the graff enters a transverse channel 900
containing a cross-
directed gathering auger 901 (which preferably has a diameter of 43 cm (17
inch)). The purpose
of this auger is to reduce the width of the graff flow from that of the graff
conveyor 100'
(approximately 3m or 3.3 m ( 10 or 11 feet)) to that of the width of the
cleaning mill itself, which
is somewhat narrower (approximately 143 cm (56 inches)). By this means, the
both the cleaning
mill and the conveyor may be designed to have optimal widths for their
intended functions, even
though those widths may differ.
In this embodiment, the screening unit 103 of the previous embodiment is
incorporated
into the main body 905 of the cleaning mill 20'. This makes the cleaning mill
more compact and
easier to operate. As shown in simplified schematic form in Fig. 14, upon
leaving the transverse
channel 900 at the central opening 975, the graff falls onto a grain pan 907
provided with a
reciprocating action that tends to stratify the graff into components of
different density and levels
the graff into an even carpet 908 having a width of 0.6 to 1.2 m (2 to 4
feet). The grain pan
moves the graff forwards until it falls onto a cleaning shoe 909. The cleaning
show includes an
upper chaffer screen 910 and a lower grain sieve 911 (both of which are of
adjustable mesh size)
that are reciprocated back and forth in an opposed motion. A short extension
sieve 912 is also
provided at the distant end of the chaffer 910. This can be adjusted
independently of the chaffer,
and can be raised at an angle to slow down the flow of material, if desired.
The chaffer and grain
CA 02311261 2000-06-09
- 29
sieve each preferably have a surface area of about 1.7 m2 (17.9 sq. ft.). The
mesh size of the
chaffer is larger than that of the grain sieve. As the graff passes through
the shoe 909, large
chaff, stalks, cut heads and stones are separated mainly by the chaffer 910
and then intermediate
contents (e.g. weed seeds, small chaff, stalk parts, etc.), are separated at
the grain sieve 911.
Essentially only grain 91 S itself passes through the grain sieve 911 and
falls to a collection pan
916 that has sloping front and rear walls directing the grain to a central
trough 917 for removal by
a cross auger 918 through a grain exit 919.
As the graff is separated into its components in this way, air is blown
upwardly and
outwardly through the shoe 909 as indicated by arrows A. This air flow
suspends essentially all
of the graff components except the grain and heavy objects such as stones. In
fact, as the graff
drops onto the shoe 909 from the grain pan 907, it encounters a blast of air
forceful enough to
blow away essentially everything but clean grain kernels of the desired size
(and heavy objects,
such as stones). This reduces the amount of separation required to be carried
out by the shoe 911
itself. Both the suspended chaff and the heavy objects proceed to a cyclone
separating unit 920.
The suspended chaff is carried by the air flow, whereas the heavy objects are
moved by the
reciprocating action of the shoe sieves into the inlet 921 of the cyclone
unit.
The airflow is created by a fan 925 (e.g. a 16.5 kW (22 hp) centrifugal fan
creating a
throughput of 400 m3/min (4,000 cubic feet/minute)) positioned within the
cleaning mill beneath
the graff conveyor 100'. The fan directs air into conduit 926 leading to the
cleaning shoe 909,
but an adjustable diverter 927 is provided upstream of the shoe to direct a
portion of the air into a
bypass conduit 930 as indicated by arrows B. The air from the bypass 930
nevertheless also
enters the cyclone unit 920 with the air that has passed through the cleaning
shoe 909. The
diverter allows the airflow A through the shoe to be made appropriate for
cleaning the graff
(designed to blow away everything below kernel removal) while still allowing a
high rate of
airflow through the cyclone unit 920. The diverter 927 may be either manually
adjustable or
automatically controlled based on the rate of feed of graff into the cleaning
mill.
A stone cleanout door 932 is provided at the bottom of the cyclone unit 920 to
allow
stones and other large or heavy objects to be removed periodically from the
bottom of the cyclone
unit where they tend to collect as they are not removed by the airflow.
The cyclone unit 920, by virtue of the spiral flow of air there through and
the density of
the suspended chaff, causes the suspended chaff to congregate around the
inside wall 935 of the
unit so that clean air that is substantially free of chaff and other solids
may exit the unit through a
central opening 936. The chaff, propelled by a further flow of air, exits a
chaff delivery port 937
located at an outside lower region of the cyclone unit. The clean air is
recirculated directly to the
CA 02311261 2000-06-09
- 30
_ fan 925 via ducting 940 (see Fig. 15), although a certain amount of clean
air from the outside may
be introduced into the recirculated air, e.g. through an elongated slot
provided adjacent to the
graff entrance I 17', to replace air escaping with the chaff and to reduce the
build-up of dust
(about 90% recirculation is usual).
The solids exiting chaff delivery port 919 contains chaff proper, weed seeds,
unthreshed
heads, and small grain kernels. As shown in Fig. 15, this is conveyed through
ducting 950 to a
high speed centrifugal material-conveying fan 951 provided with paddle-like
blades. The fan has
a hammering, impacting or chopping effect that reduces the size of large items
and tends to crack,
nick or crush weed seeds and small grain kernels (thus making them less liable
to germinate).
l0 The fan is preferably operated at a speed of about 3293 rpm, giving the fan
a velocity at its blade
tips of about 440 km/hr and a throughput of about 57 m3/min (2000 cubic
feet/minute).
Obviously, variations (e.g. ~ 10%) of these speeds and velocities may be
employed, provided the
desired material conveying and seed cracking effects are obtained. The
material exiting the fan is
then conveyed through tubing 952 to a desired location where it is discharged
to form an open
pile (not shown) (or it may, if desired, be discharged into a silo or other
form of container,
however the crushed millings adhere to themselves and cake together so the
material tends not to
blow away from an open pile). The millings form a good quality animal feed
similar in nutrient
content to hay. The fan 951 and tubing 952 may convey the solids up to a
distance of about 60 m
(200 feet) from the cleaning mill, depending upon the power of the fan 951.
The fan 951 acts to
both convey the separated solids and to crush them. It acts at a fast rate of
throughput and is
rarely subject to blockage, plugging or failure for other reasons. This is all
achieved at a
reasonable cost in power to operate the fan.
In a preferred form of this embodiment, as shown, a single motor 955 is used
to drive
both the air fan 925 and the material-conveying fan 951. This is preferably a
written pole (single
phase) electric motor of 30 to 37.5 kW (40-50 hp). Approximately eight
additional small electric
motors (of approximately 1.5 - 2.25 kW (2-3 hp) each) are required for the
complete operation of
the cleaning mill. Advantageously, all these motors may be designed to operate
on single phase
power that is most readily available on farms and in remote areas.
The cleaned grain exits the grain delivery port (propelled by the positive air
pressure in
the cleaning mill or extracted by an auger) and is delivered by an auger to a
storage container
(e.g. one or more silos - not shown).
The cleaning mill of this embodiment maintains a constant recirculation of air
and a
constant stream of graff into the mill and constant streams of cleaned grain
and the remaining
constituents from the mill. The illustrated unit is capable of processing
91,000 litres (2500
CA 02311261 2000-06-09
31
bushels) of graff per hour. The receiving unit 21' is capable of holding at
least 27,000 litres (750
bushels) of graff. A single load from a truck can therefore be processed in
about 20 minutes.
The mill can be essentially left to operate without supervision. The truck
operator can use
a remote control device to lower the receiving unit as the truck approaches,
dump the load of
graff, and then set the cleaning mill in operation and leave for another load.
The mill may be
computer controlled to raise the receiving unit in stages to feed the graff
conveyor appropriately,
and to run all of the fans and motors until a sensor indicates that all of the
graff has been
processed. The unit may then shut itself off automatically, awaiting the next
load.
