Cleaning means for an agricultural harvesting machine

A combine harvester (1) is provided with a grain cleaning mechanism (12), comprising a fan (33) installed in a generally volute-shaped fan housing (72), having primary air inlets (73) in its side walls and a secondary air inlet (74) in its top wall. The housing (72) further has a main outlet duct (80) directed to a chaffer sieve (31) and a lower grain sieve (32) and an additional outlet duct (81) directed to a pre-cleaning sieve (29) and an associated grain pan (30). The secondary air inlet (74) is covered with a plurality of juxtaposed plates (75), comprising sets of louvres (76) which are opened rearwardly. Grain kernels which unwantedly fall off the leading edges of the sieves (29, 31, 32) or the grain pan (30) and into the outlet duct (80, 81), may be engaged and thrown upwardly by the blades (95) of the fan (33), but will be returned into the fan housing (72) by the louvres (76), which nevertheless do not obstruct an efficient air intake by the fan (33) .

FIELD OF THE INVENTION 
The present invention relates generally to agricultural harvesting 
machines, such as combine harvesters, and more specifically to the 
cleaning means, which is used for separating grain kernels from 
discardable material, such as coils, chaff and straw particles, under 
action of a fan which is mounted in an improved fan housing. 
BACKGROUND OF THE INVENTION 
Current harvesting machines have been developed for meeting the increasing 
needs of capacity and output under a wide range of field and crop 
conditions. In modern high capacity combine harvesters, one of the 
critical factors is the capacity of the cleaning means, comprising grain 
pans and sieves for receiving and cleaning the crop material from a 
threshing and separating mechanism. Besides grain kernels, this threshed 
crop material comprises discardable material, such as chaff and straw 
particles, which is blown out of the combine harvester by a ventilator or 
fan. In order to obtain an effective cleaning action, the fan has to 
generate a forceful and even air flow over and through the complete width 
of the sieves. 
To that end, a conventional centrifugal fan structure, which comprises a 
fan, mounted in a generally volute-shaped housing with central air inlets 
in the side walls and a main air outlet duct directed towards the sieves, 
has been provided with an secondary air inlet in the top wall of the 
housing. Such configuration has been disclosed in GB-A-2,063,034. In order 
to keep impurities, such as crop stems, out of the fan housing, the 
secondary air inlet is provided with a perforated shield. For an effective 
air flow, deflector plates can be mounted in the air duct between the fan 
and the sieves, but no other obstructions may be placed therein. The air 
flow is directed via a main outlet duct towards an upper chaffer sieve and 
a lower cleaning sieve and via an additional outlet duct towards a 
pre-cleaning sieve and an associated grain pan. Said sieves and grain pan 
extend rearwardly and slightly upwardly to the rear of the harvester. 
It has been experienced that under some circumstances grain kernels can 
move towards the forward end of the sieves and the associated grain pan 
and fall into one of the outlet ducts. This happens when their front 
portion is fully loaded with crop material and the combine harvester is 
suddenly halted and/or reversed. The crop material may also slide into the 
outlet ducts during downhill travel of the combine harvester. The air flow 
from the fan may blow back the lighter portion thereof towards the sieves, 
but this effect quickly diminishes when the sieves are fully loaded and 
the air flow is choked consequently. Even during normal operation of the 
harvester, crop particles may roll to and over the forward edge of the 
sieves: this occurs when the front portion of the sieves or the associated 
grain pan is polluted with a layer of sticky crop material. The even 
surface thereof gets no grip on the newly arriving crop particles, which 
migrate downwardly and forwardly until they fall into one of the outlet 
ducts. 
The heavier portion of the crop material, including the grain kernels can 
penetrate further into the outlet ducts, until it is engaged by the blades 
of the rotating fan. Most of the grain kernels are projected one or 
several times against the walls of the fan housing and are finally 
launched into the main outlet trough and the clean grain auger duct below 
the lower cleaning sieve, from where they are conveyed to the grain tank. 
A considerable amount of kernels, however, is thrown upwardly and through 
the holes in the perforated plate of the secondary air inlet. They are 
scattered around the fan housing and fall on the field or accumulate on 
top of near harvester parts, such as the traction gearbox and the traction 
beam. 
These grain losses are easily spotted and, although their cause may be 
incidental, e.g. a sudden halt of the machine, the losses should be 
avoided to the maximum extent. When they result from harvesting operations 
during prolonged downhill travel, one could consider to reduce the 
travelling speed of the harvesting machine in order to diminish the load 
on the sieves and hence the tendency of the crop material to slide to the 
leading edges of the sieves and the grain pan, but the consequent capacity 
losses largely exceed the value of the grain lost through the secondary 
air inlet. 
The grain losses could also be reduced by reducing the diameter of 
apertures in the perforated plate, but this will have a choking effect on 
the air flow through this inlet and hence affects the efficiency of the 
fan structure. 
SUMMARY OF THE INVENTION 
It therefore is the object of the present invention to provide an 
economical and effective solution for these grain losses without affecting 
the air flow through the air inlets. This is accomplished by providing the 
fan housing with a structure which returns the crop material, which was 
engaged by the rotor blades, into the housing and still permits the intake 
of cleaning air therethrough. 
According to the present invention an agricultural harvesting machine is 
provided, comprising a threshing and separating mechanism for threshing 
and separating crop material, and a cleaning device for cleaning the 
threshed and separated crop material, which cleaning device comprises fan 
means having a generally volute-shaped fan housing with a primary air 
inlet in at least one side wall, a secondary air inlet in its 
circumference wall, and a generally rearwardly directed air outlet, and a 
fan rotor, installed for rotation within the housing and operable to draw 
in air through the primary air inlet and the secondary air inlet and to 
propel it through the air outlet. The cleaning device further comprises 
sieve means and/or grain pan means, installed for oscillation near the air 
outlet and operable to move the threshed and separated crop material 
theretrough and/or therealong. More particularly, the invention 
contemplates a harvesting machine in which the secondary air inlet is 
provided with a set of louvres operable to return crop particles, falling 
from the sieve means and/or grain pan means and being engaged by the 
rotor, into the fan housing. 
The foregoing and other objects, features and advantages of the invention 
will appear more fully hereinafter from a consideration of the detailed 
description which follows, in conjunction with the accompanying sheets of 
drawings wherein one principal embodiment of the invention is illustrated 
by way of example. It is to be expressly understood, however, that the 
drawings are for illustrative purposes and are not to be construed as 
defining the limits of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As illustrated in FIG. 1, a combine harvester, generally indicated at 1, 
comprises a main chassis or frame 2, supported on a fixed front axle 3 and 
a oscillating rear axle (not shown). The front axle 3 carries a traction 
gearbox 4, which is drivingly connected to a pair of drive wheels 5, 
supporting the front portion of the frame 2. The rear axle is supported by 
a pair of steerable wheels 6. Mounted onto the main frame 2 are an 
operator's platform 8, with an operator's cab 9, a grain tank 10, a 
threshing and separating mechanism 11, a grain cleaning mechanism 12, and 
a power plant or engine 13. A conventional header 14 and straw elevator 15 
extend forwardly of the main frame 2 and are pivotally secured thereto for 
generally vertical movement, which is controlled by extensible hydraulic 
cylinders 16. 
As the combine harvester 1 is propelled forwardly over a field with 
standing crop, the latter is severed from the stubble by a sickle bar 17 
at the front of the header 14 and guided by a reel 18 and an auger 19 to 
the straw elevator 15, which supplies the cut crop to the threshing and 
separating mechanism 11. The crop received therein is threshed and 
separated, that is to say, the crop is rubbed and beaten, whereby the 
grain, seed or the like, is loosened and separated from the straw, coils 
or other discardable part of the crop. 
The combine harvester 1, illustrated in FIGS. 1, comprises a conventional 
threshing and separation mechanism 11 including a threshing cylinder 20, a 
straw beater 21 and a separator rotor 22, cooperating with a set of 
concaves 23. Conventional straw walkers 24 are operable, in use, to 
discharge a mat of remaining crop material (i.e. mainly straw as most 
grain is separated therefrom) through a straw hood 25. 
Grain which has been separated by the threshing and separating mechanism 11 
falls onto a first grain pan 28 of the cleaning mechanism 12, which 
further also comprises a pre-cleaning sieve 29, positioned above a second 
grain pan 30, an upper chaffer sieve 31 and a lower grain sieve 32, 
disposed one above the other behind and below the pre-cleaning sieve 29, 
and a cleaning fan 33. The actual operation of the cleaning mechanism 12 
will be discussed further, after a more detailed description of its 
components. 
Clean grain falls to a clean grain auger 35 in a clean grain auger trough 
36 and is subsequently transferred by the auger 35 and an elevator 
mechanism (not shown) to the grain tank 10. Incompletely threshed ears, 
the so-called "tailings", fall to a tailings auger 37 (only shown in FIG. 
2) in a tailings auger trough 38. The tailings are transported sideways by 
this auger 37 to a separate rethresher 39 and returned to the first grain 
pan 28 for repeated cleaning action. 
A grain tank auger 42 at the bottom of the grain tank 7 is used to urge the 
clean grain sideways to an unloading tube 43, wherein it is elevated by an 
unloading auger 44 for discharge from the harvester 1. 
As shown in FIG. 2, the first grain pan 28 has a generally horizontal, 
stepped surface, which extends from below the forward edge of the 
threshing concaves 23 to the forward edge of the straw walkers 24, and is 
thus disposed to receive threshed and separated material from the concaves 
23 and the forward portion of the straw walkers 24. A conventional comb 
assembly 47 is secured to the discharge end of the first grain pan 28. 
The first grain pan 28 is suspended adjacent its forward end on a pair of 
cranks 48 and at its rear end via pivots 49 to an upper cleaning shoe 50. 
The upper cleaning shoe 50 extends from the discharge end of the first 
grain pan 28 to the rearwardmost end of the cleaning mechanism 12. 
Adjacent its rearward end, the upper cleaning shoe 50 is movably supported 
via rocking arms 52 at pivots 51 on the main frame 2. The pre-cleaning 
sieve 29, the second grain pan 30 and the chaffer sieve 31 are all carried 
by the upper cleaning shoe 50. 
The pre-cleaning sieve 29 extends rearwardly and slightly upwardly from a 
location below and forwardly of the discharge end of the first grain pan 
28. At its rear end the pre-cleaning sieve 29 carries a comb assembly 54 
similar to the assembly 47. 
The second grain pan 30, which is located below the pre-cleaning sieve 29, 
terminates short of the rear end of the latter. 
The forward end of the chaffer sieve 31 is located below and forwardly of 
the discharge end of the pre-cleaning sieve 29. Therefrom, the chaffer 
sieve 31 extends rearwardly and slightly upwardly to the rear end of the 
upper cleaning shoe 50. Between the second grain pan 30 and the chaffer 
sieve 31 a discharge opening 55 is provided. 
A lower cleaning shoe 57 is arranged below the upper cleaning shoe 50 and 
comprises a clean grain conveyor floor 58 and a tailings conveyor floor 59 
terminating respectively above the clean grain auger 35 and the tailings 
auger 37. The lower cleaning shoe 57 is arranged to support the lower 
grain sieve 32 so that it has its forward edge forwardly of and below the 
discharge end of the second grain pan 30 and its rear edge forwardly of 
and below the rear end of the upper chaffer sieve 31. 
The lower cleaning shoe 57 is movably supported on the frame 2 at pivots 61 
(frame not shown) via rock arms 62 and at pivots 63 (frame again not 
shown) via rock arms 64. The rock arms 64 on both sides of the cleaning 
mechanism 12 are extended above the level of the pivots 63 and are 
pivotally coupled at 65 to the upper cleaning shoe 50. 
The drive means for the cleaning shoes 50, 57 comprise crank shafts 66 
extending between eccentrics 67 on an intermediate shaft 68 and pivots 69 
on the lower cleaning shoe 57. 
In a conventional manner, the sieves 29, 31, 32 comprise a plurality of 
angularly adjustable and overlapping louvres, which together form a mesh 
for grain to pass through. 
Fan means, generally indicated at 71 (FIG. 3) are disposed generally behind 
the traction gearbox 4 and below the first grain pan 28. They comprise the 
fan 33 and a generally volute-shaped fan housing 72, having a pair of 
opposed primary air inlets 73 in the side walls. A secondary air inlet 74 
is provided in an upper portion of the housing 72 over the full width 
thereof. This secondary air inlet 74 is covered by a plurality of similar 
juxtaposed plates 75, comprising each a set or rearwardly opened louvres 
76. 
Over its full width, the fan housing 72 has an outlet 78, which 
communicates with a combined outlet structure comprising a main outlet 
duct 80 and an additional outlet duct 81. 
The main outlet duct 80 extends upwardly and rearwardly and faces the 
underside of the lower sieve 32, the underside of the chaffer sieve 31 and 
the discharge opening 55 between the second grain pan 30 and the lower 
sieve 32. The main outlet duct 80 comprises a bottom wall 83 and a top 
wall 84, which is oriented generally parallel to the bottom wall 83. The 
top wall 84 has a rounded forward end, spaced from the circumscribing 
circle 89 of the fan 33 and extending into a substantially vertical wall 
86 which forms part of the additional outlet duct 81. A pair of deflector 
baffles 87 is angularly adjustably mounted in the main outlet duct 80. 
The additional outlet duct 81 is confined by the wall section 86 already 
mentioned and a further wall section 88, which extends generally parallel 
to a tangent to the circumscribing circle 89 of the fan 33 and has its 
lower edge closely adjacent that circle 89 and at a distance slightly 
above the level of the lower end of the wall section 86. The upper portion 
of the wall section 88 is curved through almost 90.degree. and faces 
rearwardly and upwardly, being located above the level of the top edge of 
the other wall section 86, which comprises a sealing strip 90, sealingly 
engaging the underside of the second grain pan 30. The additional outlet 
duct 81 is disposed so that its outlet faces the area between the 
discharge end of the first grain pan 28 and the leading edge of the second 
grain pan 30. The leading edge of the pre-cleaning sieve 29 is positioned 
at about the middle of this area. 
The secondary air inlet 74 extends from the upper edge of the wall section 
88 in the direction of rotation 91 of the fan 33, whereby this additional 
inlet is located forwardly of the outlet 78 with respect to said direction 
of rotation 91. 
The fan 33 comprises a central shaft 93 with a number of supporting arms 94 
extending generally radially outwardly therefrom and carrying at their 
outer ends fan blades 95 having inner and outer sections, which are curved 
forwardly relative to the direction of rotation 91. These fan blades 95 of 
generally concave shape together with the primary inlets 73 and the 
secondary air inlet 74 make the fan means 71 act as a combination of a 
so-called "centrifugal fan" and a so-called "cross-flow fan". 
The inlet plates 75 extend between the forward end of the secondary air 
inlet 74 and the top of the forward wall section 88 of the additional 
outlet duct 81. The full width of the fan housing 72 is covered with the 
juxtaposed inlet plates 75, which have a convex front portion, in 
alignment with the cylindrical portion of the housing 72 and positioned 
above and forwardly of the fan shaft 93, and a flat rear portion which 
lies in a substantially horizontal plane. The rearwardly opened louvres 76 
in both plate portions have a constant opening angles .alpha., which can 
be defined as the angles between the louvres 76 and the straight line 
connecting the lower ends of the louvres 76 in the flat portion of the 
plates 75, or as the angles between the louvres 76 and the tangents to the 
circle arc connecting the lower ends of the louvres 76 in the convex 
portion of the plates 75. These angles .alpha. are substantially equal to 
30.degree.. The distance between the top edges of the louvres 76 and the 
lower edges of the following louvres 76 is substantially equal to 12 mm, 
i.e. significantly larger than the thickness of the largest crop kernels 
(corn, peas or beans). 
The inlet plates 75 with the louvres 76 are made out of sheet metal by 
means of a stamping operation, which leaves a rim of flat material around 
the louvres 76 (FIG. 4). The plates 75 have a small overlay 96 for 
spotwelding to each other and to the side wall of the fan housing 72. 
Their number is adapted to the overall width of the fan housing 72. 
Different housing widths for application to different combine models can 
be covered with one type of plate 75 in different numbers, thus permitting 
a valuable standardization of the components. 
When the cleaning mechanism 12 is in operation, the fan 33 is rotated in 
the direction 91 and the cleaning shoes 50, 57, with the elements attached 
thereto, are oscillated. Cleaning air blasts are directed through the 
outlet ducts 80, 81 of the fan housing 72. 
Material separated through the threshing concaves 23 falls onto the first 
grain pan 28, building a crop material layer thereon, which, especially on 
large capacity combine harvesters, may be relatively thick. By virtue of 
the oscillatory movement of the grain pan 28, the material thereon is 
gradually moved towards its discharge end, whilst allowing the heavier 
grain kernels to "sink" to the lower portions of the layer and thus 
allowing the lighter chaff, straw, dust and other lightweight impurities 
to rise to the top. 
As the layer of crop material drops off the discharge end of the grain pan 
28 towards the pre-cleaning sieve 29, it is subjected to a strong air 
blast from the additional fan outlet duct 81. A major portion of the 
lightweight impurities immediately becomes airborne and is moved in the 
direction of the discharge end of the cleaning mechanism 12. 
A layer of crop material of already reduced thickness thus falls on the 
pre-cleaning sieve 29, the mesh of which is adapted to the kind of crop 
being handled. A cleaning air blast is directed from below and through the 
pre-cleaning sieve 29 as well as through the area between that sieve 29 
and the second grain pan 30 therebelow. As the layer is moved across the 
sieve 29 towards its discharge end, grain which has been cleaned to a 
great extent, falls through the pre-cleaning sieve 29 and across said air 
blast onto the second grain pan 30 and is conveyed therefrom directly to 
the lower grain sieve 32. As the grain falls from the second grain pan 30 
to the lower sieve 32, it is again subjected to a cleaning air blast which 
this time issues from the main fan outlet duct 80. 
The remainder of the layer of crop material on the pre-cleaning sieve 29 
falls onto the chaffer sieve 31. Again a cleaning air blast, also issuing 
from the additional outlet duct 81 is directed onto this layer during its 
fall. A further percentage of impurities thus becomes airborne and, 
together with the impurities coming from the stage above, is carried out 
of the machine. 
A cleaning air blast from the main outlet duct 80 is directed through the 
areas below the chaffer sieve 31 and the lower grain sieve 32 as well as 
through those sieves 31, 32 from below, so that the remaining impurities 
become airborne and are blown out of the machine whilst cleaned grain 
falls through the sieves 31, 32 and through the cleaning air blasts onto 
the clean grain conveyor floor 58, which conveys the cleaned grain to the 
clean grain auger 35 for transport to the grain tank 10. 
The fan means 71 operate partially as a centrifugal fan and partially as a 
cross flow fan. The fan blades 95 are operable to draw air in not only 
through the opposed primary inlets 73 as in centrifugal fans, but also 
through the transverse secondary inlet 74 as in cross flow fans. As a 
result, the cleaning air blast is distributed evenly transversely of the 
fan means 71, even when a relatively wide cleaning fan 33 is employed. 
The major portion of the cleaning air is expelled from the fan housing 72 
through the main outlet duct 80, whilst the remainder is directed through 
the additional outlet duct 81. The direction of the blast of cleaning air 
issuing from the main outlet duct 80 and directed to the chaffer sieve 31 
and the lower sieve 32, is adjustable by the angularly adjustable baffles 
87. 
In order to avoid obstruction of the wind blast at the leading edges of the 
sieves 29, 31, 32 and the second grain pan 30, no means are provided for 
retaining crop material which has piled up in the forward portions of 
these sieves 29, 31, 32 and grain pan 30. Under normal circumstances, the 
oscillatory movement of the cleaning shoes 50, 57 suffices to convey the 
material rearwardly and away from these leading edges. In some cases, 
however, the layer of crop material may slide forwardly and fall into one 
of the outlet ducts 80, 81. 
This occurs when the forward portion of the pre-cleaning sieve 29, the 
lower grain sieve 32 or the second grain pan 30 is fully loaded and the 
combine harvester 1 is halted and/or reversed abruptly. The inertia of the 
crop material makes it roll to and over the leading edges of the sieves 
29, 32 or the grain pan 30, where it is engaged by the air blast through 
the outlet ducts 80, 81. The lighter portion of the falling crop material, 
such as chaff, dust and straw particles, may still be lifted up and blown 
back towards the rear of the harvester 1 by the air blasts trough the 
outlet ducts 80, 81, but the grain kernels can penetrate much further in 
the outlet ducts 80, 81 and eventually reach the bottom wall 83 of the fan 
housing 72. These kernels roll down the bottom wall 83 and accumulate at 
the lowest point below the fan shaft 93, where they build a layer between 
the side walls of the housing 72. 
As there is only a small spacing between the bottom of the housing 72 and 
the circumscribing circle 89 of the fan blades 95, the kernels at the top 
of this layer are engaged by the tips of said fan blades 95, which project 
most of these kernels rearwardly through the main outlet duct 80 and into 
the lower cleaning shoe 57, where this portion of the clean grain is 
recovered either directly or indirectly on the grain conveyor floor 58 and 
transported therefrom to the clean grain auger trough 36. 
Another portion of the clean grain, however, is lifted up by the fan blades 
95 and launched against the walls of the fan housing 72. Most of the 
kernels which are thrown upwardly, are returned by the louvres 76 in the 
secondary air inlet 74, before they can reach the underside of the first 
grain pan 28 and be scattered around the fan means 71. Some kernels may be 
projected rearwardly and, if they reach the plate 75 under the angle 
.alpha., inbetween the louvres 76. As these kernels are returned by the 
steps on the underside of the first grain pan 28, they fall back onto the 
louvres 76 and are guided by the slanted louvres 76 and the incoming air 
into the fan housing 72. The dimensions of the gaps at the entrance of the 
consecutive louvres 76 prevent that the latter are plugged with kernels or 
other crop material. No kernel projected by the fan blades 95 can pass the 
upper wall 75 along a forwardly directed straight or ballistic curve and 
end up in front of the housing 72, which was the case when a perforated 
plate was installed over the inlet 74. 
Inside the housing 72, the returned grain is caught once more by the fan 
blades 95 and delivered directly or after repeated projections against the 
walls of the housing 72 to the lower cleaning shoe 57 and the clean grain 
auger 35 for further transport to the grain tank 10. Thus is secured that 
clean grain, which has fallen into the fan housing 72, remains within the 
machine and is not lost on the field. 
Crop material may also slide forwardly and fall off the sieves 29, 32 and 
the second grain pan 30, when their forward portions are plugged and 
covered with a layer of kernels and sticky debris. The even surface of 
this layer has no grip on the newly arriving crop material, which is also 
not subjected to an air flow through the plugged portion of the sieves 29, 
32, so that the kernels can roll down to the leading edges of the slanted 
sieves 29, 32 or second grain pan 30 and into the outlet ducts 80, 81. 
Also when the combine harvester 1 is travelling down a steep hill, crop 
material migrates to the forward portions of the sieves 29, 32 and the 
second grain pan 30. In the latter case, a portion of the grain kernels, 
which fall from the pre-cleaning sieve 29 and the second grain pan 30 into 
the additional outlet duct 81, passes along the substantially vertical 
wall section 88 and is engaged by the tips of the fan blades 95, before it 
can reach the bottom of the fan housing 72. These grain kernels are also 
projected upwardly against the louvres 76 of the secondary air inlet 74 
and thereby returned into the housing 72. In the end they are delivered to 
the main outlet duct 80 and the clean grain auger trough 36 for further 
transport to the grain tank 10. 
Another portion of the grain kernels falling off the pre-sieve 29 and the 
second grain pan 30 passes along the rear vertical wall 86 of the 
secondary air outlet and reaches the bottom of the housing 72, where it 
can accumulate together with the grain which has fallen off the lower 
grain sieve 32 and rolled down the main outlet duct 80. These grain 
kernels are cleared from the fan housing 72 in the same manner as the 
kernels which fell therein after an abrupt halt of the combine harvester 
1. The chaff, dust and straw particles, which reach the housing 72 are 
blown out of the harvester 1, while the heavier grain kernels are 
recovered and conveyed towards the grain tank 10. 
While the preferred structure in which the principles of the present 
invention have been incorporated is shown and described above, it is to be 
understood that the invention is not to be limited to the particular 
details, as shown and described above, but that, in fact, widely different 
means may be employed in the practice of the broader aspects of the 
invention.