AU3621693A - Improvements in and to combine harvesters - Google Patents

Description

IMPROVEMENTS IN AND TO COMBINE HARVESTERS

This invention relates generally to combine harvesters and, more particularly, to improved means and method of achieving the separation of the relatively heavy threshed grain from the lighter chaff/straw during the threshing operation-

It is of course well known for combine harvesters to incorporate a cleaning system which relies on a flow of air in order to render the chaff and straw airborne and separate same from the heavier grain which is then able to pass through a set of sieves relying on gravitational force. The capacity and the efficiency of conventional cleaning systems have been found to be significantly affected when the harvester is operating on sloping ground due in part to the irregular distribution of threshed grain on the cleaning sieves. Furthermore, particularly with cleaning systems which incorporate walkers, it has been found, in practice, that the density of the straw moving along the straw walkers is such that it impedes the ability of the threshed grain to gravitate into the cleaning sieves. Accordingly it is desirable to increase both the capacity and the efficiency of cleaning systems in combine harvesters so as not to limit the throughput capability of the combine.

With conventional combines that have a threshing unit comprising a threshing drum/concave combination, it has been found that occasionally the concave becomes choked with straw due to the inability of the threshed material to be delivered efficiently from the exit end of the thresher. Such choking often leads to overloading and cracking of the threshed grain and results in more threshed grain being deposited on the walkers which in turn may lead to threshed grain being expelled with the unwanted residue from the machine. Accordingly, it is desirable to ensure that the concaves are maintained in a relatively clean condition which not only will significantly reduce the power requirement of the thresher but allows the threshed material to leave the threshing location at an ideal throughput speed so as to avoid blockage or choking.

Still further, where a shaking grain tray is used to convey threshed material from the threshing area to the cleaning sieves, and overloading occurs in the threshing unit, a significant amount of grain will be lost due to it not being able to gravitate downwardly through the chaff/straw mixture which is also on the tray, by the time the grain reaches the end of the shaking tray.

As stated previously, whilst many attempts have been made to improve the capacity and efficiency of conventional combines by means of fans or blowers so as to create a flow of air in order to urge unwanted residue in the threshed grain into an airborne state, none of these have proven to be totally successful, and in particular none have recognised the need to efficiently dissipate the threshed material from the threshing area.

It is the main object of the present invention to provide an improved means and method of threshing crop material which obviates the aforementioned prior art problems and which results in a significant increase in the capacity and efficiency of a conventional combine.

It is another object of the present invention to provide an improved means and method of threshing crop material which will allow a combine to more efficiently operate in hilly conditions where the sieves have one side higher than the other, by allowing the threshed grain to pass through the sieves at a faster rate than would otherwise be the case.

Broadly according to this invention therefore, there is provided an improved method of threshing crop material in a combine harvester having an infeed mechanism for feeding crop material into the threshing unit of the harvester, a grain cleaning mechanism and grain transfer means for conveying threshed material from the threshing unit to an intake of the cleaning mechanism, characterised by subjecting the material, being threshed by the threshing unit, to a high velocity, low volume directional flow of air which is directed along a path between the underside of the threshing unit and the transfer means, said directional flow of air being effective to assist the delivery of the threshed material away from the threshing unit and to pre-clean the threshed grain moving along the transfer means by urging the chaff and straw into an airborne state prior to reaching the cleaning mechanism.

Preferably a jet of air having a velocity in the order of 4000 to 6000 ft/minute and a flow rate in the range of 1800 to 4000 cubic ft/minute is used to dissipate and to pre-clean the threshed material.

The jet of air is preferably injected into the threshing area through a narrow, elongate nozzle opening which is orientated so as to direct the jet of air in an upwardly inclined plane with respect to the plane of the grain transfer means. The upwardly inclined directional flow of air essentially prevents threshed grain moving along the transfer means being "blown" therefrom and expelled with the lighter residue.

It is believed that the high velocity flow of air blowing across the top of the grain transfer means (in non-parallel relation therewith) creates a series of vortices (turbulent flow) immediately above the transfer means which are effective to put the light residue material which might otherwise remain with the threshed grain, into an airborne state. In operation, relatively clean grain accumulates at the distal end of the transfer tray and it has been found in practice, that the threshed grain can be up to 75% pre- cleaned prior to entering the intake of the grain cleaning mechanism. Preferably the jet of air is created by an externally mounted centrifugal fan connected to air delivery means which has an elongate nozzle at its exit end located approximately immediately below the discharge end of the infeed mechanism to the threshing unit.

Preferably, the air delivery means comprises a distributor manifold having a series of aligned air outlets and an inlet which connects to the fan by means of a flexible conduit and an injection manifold having a series of air inlets and an outlet which forms the elongate nozzle, the air inlets being respectively connected to the air outlets of the distributor manifold by separate hoses. This ensures that the flow of air is uniformly or evenly spread across the width of the nozzle as it issues therefrom.

Preferably the nozzle of the injection manifold is defined by an opening or aperture having a width in the order of 20-25mm and a length which may vary between 750-1500mm depending on the length of the threshing drum.

Preferably the discharge nozzle is provided with an adjustable flap for adjusting the direction of the jet of air issuing therefrom.

In a preferred embodiment of the invention, the nozzle of the injection manifold has its leading edge adjacent the upstream end of a grain shaker tray or pan of the grain transfer means which receives threshed grain directly from the threshing unit, such grain being transferred along the length of the shaker tray into cleaning sieves.

According to another aspect of this invention, there is provided an improved combine harvester machine of the type comprising an infeed mechanism for feeding crop material into a threshing unit, a grain cleaning mechanism for cleaning unwanted residue from the threshed grain, and grain transfer means for conveying threshed grain from the threshing unit to the grain cleaning mechanism, the improvements comprising: blower means mounted on the machine, air delivery means, one end of which is connected to said blower means, the other exit end of which terminates at a location proximate to and below the discharge end of said infeed mechanism, said blower means and said air delivery means being operable to create a high velocity, low volume directional flow of air which flows essentially longitudinally of the machine, between the threshing unit and the grain transfer means, said directional flow of air being effective to assist the movement of the threshed material away from the threshing unit and also to pre-clean the threshed grain, prior to reaching said cleaning mechanism, by urging the lighter waste material, eg chaff, into an airborne state.

In practice, with this invention, it has been found that the capacity of the combine harvester can increase by up to 100%, such an increase being attributable to the increased efficiency of separating the threshed grain and the straw/chaff in the actual threshing area of the machine and during the transference of the threshed grain to the cleaning mechanism, and the avoidance of any blockage or choking occurring in the threshing unit. In those harvesters where the cleaning mechanism comprises a walker system, it has been found that by creating an air flow stream on the underside of the walkers, the increased capacity is in part due to the easier separation of the threshed grain and the straw/chaff being conveyed along the walkers as a result of the straw/chaff being in a dynamic state. Normally there is no air flow along the walkers which in the past has been confined to the sieve area of the cleaning mechanism. The dynamic state of the residue material not only assists in the separation of the threshed grain from such material but also enables the grain to gravitate to the cleaning sieves a lot sooner. It is also believed that the unexpected results attained with this invention are also partly attributable to a swirling air effect created near the distal end of the shaker tray when the stream of air flowing above the grain transfer means merges with air which emanates from the cleaning blower which is located adjacent the cleaning sieves (in accordance with known practice) , such swirling effect causing lighter residue material to be put into an airborne state for expulsion from the machine.

In order to further explain the present invention, several embodiments of the invention are described hereunder in more detail with reference to and are illustrated in the accompanying drawings wherein;

Fig 1 shows schematically a blower arrangement according to a first embodiment, incorporated into a conventional combine harvester having a cleaning mechanism which includes straw walkers;

Fig 2 is a perspective view of a combined blower and air injection system for fitment to a harvester according to a second embodiment;

Fig 3 is a view similar to Fig 1 but incorporating the air injection system shown in Fig 2;

Fig 4 is a sectional view of the injection manifold shown in Fig 2; whilst

Fig 5 is a schematic view of the blower arrangement shown in Fig 2 fitted to a harvester of the rotary-type.

In the embodiment shown in Fig 1, a crop harvesting machine 10, commonly referred to as a combine, is of conventional construction and is arranged to sever crop material, consolidate it and feed it upwardly through an infeed conduit 11 which normally houses a chain elevator (not shown) for conveying the consolidated crop material into a threshing unit 12 for threshing the crop material in order to separate the relatively heavy grain from the lighter chaff/straw and other residue, the threshed material being conveyed to a cleaning mechanism 13 for final separation and collection of the cleaned grain.

The threshing unit 12, in accordance with known art, comprises a rotating threshing drum 14 which has fixed around its outer circumference and extending lengthwise thereof a plurality of circumferentially spaced threshing bars 15, and a concave 16 which encircles part of the drum circumference so as to provide an area of grain separation surface. Normally the concave is adjustable to correspond exactly with the threshing requirements of any crop or condition change.

Located beneath the concave 16 is a grain transfer mechanism 18 which, in this embodiment, comprises a shaker tray or pan (of known form) for conveying unclean threshed grain received directly from the threshing unit 12 to the sieve area of the cleaning mechanism 13.

Also in accordance with known art, the cleaning mechanism 13 comprises straw walkers 20 for receiving threshed material after it leaves the threshing unit 12. The threshed material should spread in an even layer over the whole of the straw walker system in order to achieve optimum grain separation effect. The straw walkers 20 are driven in a manner to ensure that threshed material moves uniformly therealong to enable the threshed grain to separate from the chaff/straw material prior to the discharge of the unwanted residue from the discharge end of the machine 10. Located below the walkers 20 are sieves 22 through which the threshed grain gravitates in-order to produce cleaned grain free from any remaining residue such as chaff and short pieces of straw. After being cleaned, the cleaned grain is then transported to a grain tank (not shown) . In accordance with usual practice, a blower fan 24 is positioned to one side of the sieves 22 and directs a flow of air across the surface of the sieves to effect a final separation of any unwanted residue from the cleaned grain.

In accordance with the practice of this invention, there is provided a centrifugal fan 25 secured to the frame of the machine 10 which is operable to produce a jet of air from the exit end of an air delivery conduit 26. In this embodiment, the discharge end of the conduit 26 is located immediately below the exit end of the delivery conduit 11 and comprises a narrow elongate opening 27, designed to direct the incoming air jet at an upwardly inclined angle between the underside of the concave 16 and the upper side of the tray 18 to thereby urge a large percentage of the chaff and straw into an airborne state immediately upon threshing. With this arrangement, the threshed material is already partially cleaned before reaching the cleaning mechanism 13.

It is essential that a high velocity, low volume flow of air be created by the blower 25 in order to dissipate the threshed aterial efficiently and also to cope with the large amount of crop material being forced through the concave of the threshing unit 12. Preferably a jet of air having a velocity in the order of 4000 to 6000 feet per minute, and a velocity pressure in the range of 3 to 14" of water, is required. Depending on the width of the machine (which determines the length of the discharge opening of the conduit 26), the volume of flow may range between 1800 to 4000 cubic f /minute.

An adjustable flap 28 can be conveniently hingedly mounted at the discharge end of the delivery conduit 26 to enable the direction of the jet of air issuing from the conduit 26 to be adjusted. In this embodiment the discharge opening 27 of the delivery conduit 26 is a nozzle opening having a width of between 20-25mm.

It is important that the stream of pressure air blown from the opening 27 retains its directional effect for a considerable distance beyond the plane of the opening. In some harvesters, eg where both the walkers and the grain auger conveyor system extend to the rear of the machine, the directional effect of the air stream is required to be maintained approximately along the full length of the machine to ensure that the airborne residue material is effectively expelled from the rear thereof and cannot re-mix with the threshed grain being fed into the cleaning sieves 22.

With the arrangement of the present invention, the efficiency of the separation of the threshed material moving along the walkers 20 is significantly improved by virtue of the jet of air creating an air flow across the underside of. the walkers 20, such air flow causing some turbulence on the underside of the walkers 20 which in turn causes the relatively light waste material, i.e. chaff, to "jump", such dynamic movement enabling the threshed grain to separate more easily and in turn be allowed to gravitate into the sieves 22.

Referring to the embodiment shown in Figs 2-4 of the drawings, where corresponding parts have been given the same numerals to those in Fig 1, the centrifugal blower 25 is mounted on the machine 10 adjacent its cab, the blower 25 being connected to a distributor manifold 31 by a flexible conduit 32, the manifold 31 in turn being connected to an injector manifold 33 by a plurality of short-length hoses 36. The injector manifold 33 is mounted in an elongate transverse opening in an end wall of the machine 10 just below the exit end of the infeed conduit 11, the manifold 33 having a transverse horizontal -elongate nozzle opening 34 which communicates with the space below the concave 16. The hoses 36 ensure that the flow of pressure air is delivered into the manifold 33 evenly across its full width, and in turn blown from the opening 34 uniformly across its entire length which can vary between 750-1500mm.

As shown in Fig 4, the manifold 33 is provided with a pair of opposed parallel walls 35, 35' which terminate at the nozzle opening 34, so that air issues from the opening 34 in a linear or straight stream at a slightly upwardly inclined angle with respect to the shaker tray 18. As discussed previously, it is advantageous that the stream of jetted air undergoes minimal dissipation, at least initially, as it flows across the top of the tray 18 so as to maintain its directional effect.

-Referring to Fig 5 of the drawings, a blower assembly similar to that shown in Figs 2-4 is shown fitted to a rotary combine harvesting machine, which incorporates a rotary cylindrical threshing drum 37 and concave 38 which extends lengthwise of the machine (rather than transversely) and a grain transfer auger 39 (rather than a shaker tray) which conveys threshed grain and lighter waste material to the cleaning sieves 40. No walkers are used. As with the previous embodiment, pressure air is blown through a flexible delivery duct to a distributor manifold which splits the air up into a number of separate flow paths by means of hoses, before passing into the injection manifold 33 which has its discharge nozzle 34 located below the threshing mechanism 37, 38 and at the upstream end of the auger 39. The fast flowing airstream 40 flows between the underside of the concave 38 and the auger 39 at a slightly inclined angle with respect to the axis of the auger 39. The number and size of the hoses 36 will vary according to the size and width of the machine.

In accordance with known art, the machine has a cleaning fan 42 for getting rid of chaff residue which may accumulate on the sieves 41; with the clean grain passing through the sieves 41 into a delivery auger 43 which delivers the clean grain to a collection bin or tank.

It will of course be appreciated that the threshing and cleaning units can be of other designs, as will be well known to those skilled in the art.

A brief consideration of the above described embodiment will indicate that the invention provides a very simple and inexpensive solution to significantly improving the capacity and efficiency of a combine machine; and one which can be readily fitted to existing machines.

Claims (17)

12The claims defining the invention are as follows:

1. An improved method of threshing crop material in a combine harvester having a threshing unit, an. infeed mechanism for feeding crop material into the threshing unit, a grain cleaning mechanism, and grain transfer means for transferring threshed material from the threshing unit to an intake of the cleaning mechanism, characterised by; subjecting the crop material being threshed by the threshing unit, to a high velocity low volume directional flow of air which is directed towards the rear of the harvester between the underside of the threshing unit and the ' transfer means, said directional flow of air being effective to assist the movement of the threshed material away from the threshing unit and to pre-clean the threshed grain, prior to reaching the cleaning mechanism, by urging the lighter chaff and straw into an airborne state.

2 . A method according to claim 1 wherein said flow of air comprises a jet of air issuing from an elongate nozzle opening, said jet of air discharging from the nozzle opening at an angle with respect to the axis of the transfer means.

3. A method according to claim 1 or claim 2 wherein said flow of air has a velocity pressure in the range of 3 to 14" of water and a flow velocity in the range of 4000 to 6000 ft/minute.

4. A method according to either claim 2 or claim 3 wherein said flow of air is created by an externally mounted centrifugal fan connected to air delivery means which terminates at its exit end in said elongate nozzle opening located approximately immediately below the discharge end of the infeed mechanism to the threshing unit.

5. A method according to any one of claims 2 to 4 wherein said nozzle opening has a width in the order of 20-25mm.

6. A method according to any one of claims 2 to 5 wherein the nozzle opening has its lower edge adjacent the upstream end of said grain transfer means.

7. An improved combine harvester machine of the type comprising an infeed mechanism for feeding crop material into a threshing unit, a grain cleaning mechanism for cleaning unwanted residue from the threshed grain, and grain transfer means for conveying threshed grain from the threshing unit to the grain cleaning mechanism, the improvements comprising: blower means mounted on the machine, air delivery means, one end of which is connected to said blower means, the other exit end of which terminates at a location proximate to and below the discharge end of said infeed mechanism, said blower means and said air delivery means being operable to create a high velocity, low volume directional flow of air which flows essentially longitudinally of the machine, between the threshing unit and the grain transfer means, said directional flow of air being effective to assist the movement of the threshed material away from the threshing unit and also to pre-clean the threshed grain, prior to reaching said cleaning mechanism, by urging the lighter waste material, eg chaff, into an airborne state.

8. An improved combine harvester according to claim 7 wherein said air delivery means terminates in a narrow elongate nozzle opening arranged to direct said flow of air in an upwardly inclined plane with respect to the plane of said grain transfer means.

9. An improved combine harvester according to claim 7 or claim 8 wherein said air delivery means comprises a distributor manifold, conduit means interconnecting the blower means and one end of said distributor manifold, an injection manifold spaced from the distributor manifold and which terminates at its exit end in an opening which constitutes said elongate nozzle opening, and a plurality of separate conduits extending between respective air outlets on the distributor manifold and spaced along the length thereof and respective air inlets spaced approximately evenly along the length of said injection manifold at its other end, whereby air is evenly discharged across the full length of said opening.

10. An improved combine harvester according to any one of claims 7 to 9 wherein said blower means comprises a centrifugal fan having a capacity to produce a flow of air having a velocity at least in the order of 4000 to 6000 ft/minute.

11. An improved combine harvester according to any one of claims 7 to 10 wherein said grain cleaning mechanism^' comprises a walker system having its leading end located approximate to the discharge end of the threshing unit and extending rearwardly therefrom, said flow of air being arranged to flow across the underside of said walker system longitudinally thereof.

12. An improved combine harvester according to any one of claims 7 to 11 wherein said injection manifold comprises walls which converge in a direction towards its exit end.

13. An improved combine harvester according claim 12 wherein said walls comprise parallel wall portions arranged to provide a linear flow of air discharging from the nozzle opening.

14. An improved combine harvester according to any one of claims 7 to 13 wherein said threshing unit comprises a rotary threshing drum which rotates about an axis which extends transversely of the machine, said nozzle opening having a length which is approximately coextensive with the length of said drum.

15. An improved combine harvester according to any one of claims 7 to 14 wherein said grain transfer means comprises a horizontally extending shaker tray, said nozzle opening being located adjacent the leading end of said tray.

16. An improved method of threshing crop material substantially as hereinbefore described and illustrated in Fig 1; Figs 2 to 4; or Fig 5 of the drawings.

17. Improvements in and to a combine harvester machine substantially as hereinbefore described with reference to and illustrated in Fig 1; Figs 2 to 4; or Fig 5 of the drawings.