WO2012123479A1 - Combine harvester re-threshing apparatus - Google Patents

Abstract

A re-threshing system for a combine harvester is provided. The system comprises a re-thresher housing (81, 82) which bounds a passage, a re-thresher auger having flighting elements (77) mounted on a shaft (73) arranged for rotation within the passage. The re-thresher housing includes one of a first and second interchangeable cover (82, 92), wherein said first cover (82) is employed in a re-threshing mode and comprises a plurality of guide vanes (84) mounted on the inside thereof and having a profile which substantially conforms to the cylindrical swept volume of the flighting. In the re-threshing mode crop material is conveyed through the passage by interaction between the guide vanes and flighting of the auger in rotation. The second cover (92) is employed in a non re-threshing mode and comprises an inner wall surface that substantially conforms to the swept volume of the flighting elements, in the non re-threshing mode crop material is conveyed through the passage by interaction between the inner wall surface and flighting of the auger in rotation. The system further comprises removable threshing fingers (80) mounted on the shaft between the flighting when in the re-threshing mode.

Description

DESCRIPTION

COMBINE HARVESTER RE-THRESHING APPARATUS

The invention relates to re-threshing apparatus employed in combines to thresh tailings recovered from a processed crop stream.

For many decades, self-propelled combine harvesters have been used by farmers to harvest a wide range of crops including cereals, maize and oil-seed rape. Typically, a combine harvester cuts the crop material, threshes the grain therefrom, separates the grain from the straw, and cleans the grain before storing in an onboard tank. Straw and crop residue is ejected from the rear of the machine.

The grain cleaning unit of most combines operates according to a well-established process in which grain and chaff cascading down from separating apparatus is subjected to an airstream created by a fan. The airstream blows the lighter chaff and dust rearwardly and out of the combine whilst the heavier material falls onto and through a series of cleaning sieves. This heavier grain mix extracted from the chaff includes a percentage of 'tailings' or 'returns' or un-threshed grain which is separated from the clean grain by one of the sieves. The clean grain is conveyed to the grain tank whilst the tailings are collected and passed through re-threshing apparatus.

It is recognised however that not all crops and harvesting conditions benefit from a re-threshing action. For example, the kernels of maize are particularly susceptible to damage is passed through a re-thresher.

United States Patent application publication No. US-2009/0143121 discloses re- threshing apparatus for a combine harvester which involves the addition of a bypass which is used to divert the crop material around the re-thresher when required. Although this helps avoid damage to prone crops, the system involves a significant number of additional components merely to deliver the bypass functionality.

It is an object of the invention to provide a re-threshing system for a combine harvester which can operate alternatively in a non re-threshing mode. It is another object of the invention to provide a re-threshing system for a combine harvester which can operate alternatively in a non re-threshing mode with few additional components.

It is another object of the invention to provide a re-threshing system for a combine harvester which can be changed between a re-threshing mode and a non re- threshing mode with minimal inconvenience to the operator.

!n accordance with the present invention there is provided a re-threshing system for a combine harvester, comprising a re-thresher housing which bounds a passage, a re- thresher auger having flighting mounted on a shaft arranged for rotation within the passage, the re-thresher housing comprising first and second interchangeable covers wherein said first cover is employed in a re-threshing mode and comprises a plurality of guide vanes mounted on the inside thereof and presenting a profile which substantially conforms to the swept volume of the flighting wherein crop material is conveyed through the passage by interaction between the guide vanes and the rotating flighting, and wherein said second cover is employed in a non re-threshing mode and comprises an inner wall surface that substantially conforms to the swept volume of the flighting elements wherein crop material is conveyed through the passage by interaction between the inner wall surface and the rotating flighting, the system further comprising removable threshing fingers mounted on the shaft between the flighting when in the re-threshing mode.

By providing an axial flow re-thresher in this way, the re-threshing action can be simply enabled/disabled by changing the surface profile presented to the flighting and adding/removing the threshing fingers. This changeover process is simple and quick thus minimising the inconvenience to the operator.

Moreover, far fewer components are required than the known system described above.

The wall of the second 'non re-threshing' or 'plain' cover preferably has a substantially semi-cylindrical profile so as to mimic one half of a conventional auger.

The system in accordance with the invention may be fitted to a combine harvester comprising a primary threshing unit arranged to receive and thresh a harvested crop stream, a cleaning unit which receives tailings, chaff and grain removed from the straw in the threshed crop stream, the cleaning unit comprising means to separate tailings from the grain.

The crop conveyance passage through the re-thresher preferably forms part of a longer returns auger between an output of the cleaning unit output and an input of the cleaning unit. Advantageously, this allows the re-threshing apparatus to be integrated into a conventional auger, in such an arrangement the re-thresher auger preferably shares a common shaft with an adjacent portion of the returns auger.

Also the flighting of the re-thresher may be continuous with flighting of the returns auger provided on the common shaft.

The first and second covers are preferably attached to tubing of the returns auger by a mechanism which enable simple interchanging. For example each of the first and second covers may be provided with mounting strips secured at each axiaily- displaced end, each mounting strip comprising a plurality of holes to align with holes formed in corresponding mounting strips secured to respective ends of adjacent auger housing portions, bolts being inserted through the holes to secure the required cover in place. Alternatively, other forms of securing the respective covers in place may be used instead, such as clamps for example.

Further advantages of the invention will become apparent from reading the foiiowing description of specific embodiments with reference to the appended drawings in which:-

Figure 1 is a left-hand side elevation of a combine harvester;

Figure 2 is a right-hand side elevation of the combine harvester of Figure 1;

Figure 3 is a sectional view through the crop processing apparatus of the combine harvester of Figure 1 ;

Figure 4 is a plan view of a returns auger in accordance with the invention shown with the re-thresher cover removed;

Figure 5 is a perspective view of the returns auger of Figure 4 shown with the non re- threshing cover in place and the re-threshing cover alongside; Figure 6 is an isometric view of the returns auger of Figure 4 shown with the corner gearbox in place;

Figure 7 shows various views of the re-threshing cover shown in Figure 5; and,

Figure 8 shows various views of the non re-threshing cover shown in Figure 5.

From reading the following description it should be understood that the terms longitudinal and transverse are made in relation to the combine harvester's normal direction of travel. In other words, the term 'longitudinal' equates to the fore and aft direction, whereas the term 'transverse' equates to the crosswise direction, or left and right. Furthermore, the terms 'axial' and 'radial' are made in relation to a rotating body such as a shaft wherein axiai relates to a direction along the rotation axis and radial equates to a direction perpendicular to the rotation axis.

With reference to Figures 1 and 2, a self-propelled combine harvester 10 comprises a header 12 (not shown in Figure 2) which cuts and gathers a strip of crop as the combine harvester is driven across a crop field. An elevator section 14 conveys the crop stream from the header 12 into a central processing apparatus 16 described in more detail below. Clean grain separated from the crop stream is collected in a storage tank 18 which is periodically emptied into a trailer (not shown) via an unloading auger 20. Residue material remaining from the crop stream such as straw and chaff is ejected from the rear of the machine represented by arrow 22. For completeness the combine 0 includes a driver's cab 24.

Turning to the details of the crop processing apparatus 16, as shown in Figure 3, the crop stream passes from the elevator 14 into a threshing unit 26 in the form of a transverse threshing cylinder which rotates in a counter clockwise direction as seen in Figure 3 around a transverse axis 27. As in known combines the crop stream is threshed between the threshing cylinder 26 and a concaved surface (not shown). Grain and chaff separated in this process falls through a grate in the concave onto an underlying thresher pan 28 forming a primary grain/chaff stream. The residue straw is conveyed rearwardly as represented by arrow 29 from the threshing unit to a transverse transfer beater 30 which also rotates counter clockwise as viewed in Figure 3. From here the crop stream is divided into two sub-streams and passed into respective !ongitudinally-aligned separating rotors, it will be appreciated that only one rotor 32 is shown in Figure 3. The transfer beater 30 has associated therewith a concave grate 34 through which further grain and chaff may fall under gravity onto the underlying thresher pan 28.

The separator apparatus in this case comprises a pair of longitudinal rotors 32, which rotate around a substantially longitudinal axis as in known axial and hybrid combines. Each separating rotor 32 has associated therewith a substantially cylindrical cage 36 within which the rotor rotates. Upon the inside upper peripheral surface of the rotor cages 36 a plurality of guide vanes 38 are mounted for cooperation with fingers 40 mounted to the rotating rotor 32 which together separate the remaining grain from the stream of straw. The lower portion of each cage 36 has a grate 42 formed therein which allows separated grain and chaff to fail under gravity onto an underlying separator pan 44 forming a secondary grain/chaff stream.

The residue straw is ejected from the process apparatus 16 at the rear of the rotors 32 as indicated by arrow 46.

Although the above described separating apparatus comprises a pair of longitudinal rotors operating on the axial separation principle, it is envisaged that these may be replaced with straw walkers known in conventional combines without deviating from the scope of the invention.

Both the thresher pan 28 and separator pan 44 are driven in an oscillating manner known in the art so as to convey the respective grain/chaff streams rearwardly and forwardly respectively. The drive mechanism for the thresher pan 28 and separator pan 44 is conventional and will be described in detail.

After falling onto the thresher pan 28 the primary grain/chaff stream is conveyed rearwardly by the oscillating motion. During conveyance the grain and chaff is stratified meaning that the heavy grain sinks to the bottom of the material layer and the lighter chaff rises to the top. This stratification of the material is of great importance and has a significant positive influence on the following cleaning process executed by the cleaning unit 48. To explain this further the stratified grain and chaff stream falls under gravity from the rear edge 49 of the thresher pan 28 into the cleaning unit 48. The secondary grain/chaff stream falls from the front edge of the separator pan 44 and combines with the primary grain/chaff stream both of which are conveyed into the cleaning unit 48.

A fan 52 generates a cleaning airstream, a portion of which is directed rearwardly between the thresher pan 28 and cascade pan 50 as represented by arrow X. The aforementioned stratification allows the lighter chaff to be blown rearwardly and carried by the airstream out of the rear of the machine as represented by arrow 54 in an uninterrupted manner whilst the heavier material falls onto the cascade pan 50.

The grain, chaff and tailings mix then falls from the rear edge of the cascade pan 50 onto a first sieve 51. A further airstream represented by arrow Y is directed rearwardly between the cascade pan and first sieve 51 and also between the successive sieves. Again, the cascading motion of the grain and chaff allows the airstream Y to convey further chaff to the rear of the cleaning unit. First sieve 51 is coarser (with larger holes) than second sieve 56 which is located under first sieve 51.

First sieve 51 and second sieve 56 are driven in an oscillating manner. Straw and material which is too large to pass through first sieve 51 is conveyed rearwardly by the oscillating motion before falling from the rear edge and out of the rear of the combine as indicated by arrow 54.

Tailings, or unthreshed grain, and grain passes through first sieve 51 onto second sieve 56. 'Clean' grain falls through second sieve 56 onto an underlying collection pan 58 which directs the clean grain to a transverse delivery auger 60 for delivering the grain to the storage tank 18.

The tailings which cannot pass through the holes in second sieve 56 are conveyed rearwardly by the oscillating motion before falling from the rear edge of the sieve 56 onto a tailings coilection pan 62 which delivers the tailings to a transverse portion of a returns auger 64.

With reference to Figures 4, 5 and 6, the returns auger comprises a transverse portion 64 and a longitudinal portion 66 drivingly coupled by a gearbox 68. Transverse portion 64 is constructed in a conventional manner with a shaft 70 having continuous flighting 71 secured thereto. Rotation is driven by a belt drive and pulley (not shown) on the left-hand side of the machine. As shown in Figure 3, the transverse portion is located in a trough 72 and open on its top side to allow collection of the tailings falling from the tailings collections pan 62.

The two portions 54, 66 of the returns auger are connected at 90 degrees by a corner module which is preferably constructed according to the auger conveyer disclosed by International Application Publication No. WO-2009/034442 A2. In summary thereof, the gearbox 68 conveys a driving force to a shaft 73 of longitudinal portion 66 by means of meshed bevel gears (not shown). The crop material is conveyed in the direction indicated by arrow A by flighting 71 of transverse auger 64 out of the main combine housing, through an aperture 74, and into a transition channel 75 defined between an outer corner wall 76a and an inner corner wall 76b (Figure 6).

The flighting 71 of transverse auger 64 is designed at the end to throw crop material radially/tangentially into the transition channel before it is collected by the flighting 77 of the longitudinal auger 66 and conveyed forwardly and upwardly in the direction indicated by arrow B. Figure 2 illustrates the incline of longitudinal auger 66.

With reference again to Figures 4 and 6, a re-thresher 78 is provided within a portion, or section, of the longitudinal auger 66. The re-thresher 78 effectively involves a modification to a section of the conventional auger construction adopted by the longitudinal auger 66.

Shaft 73 is continuous from one end of the longitudinal auger 66 to the other and is supported by bearings 79 for rotational movement. The re-thresher 78 utilizes a section shaft 73 and the flighting 77 affixed thereto. The flighting (or screw conveyor) 77 along the length of the re-thresher is standard with a continuous radial depth thus producing a cylindrical volume.

A plurality of detachable fingers 80 are mounted to the shaft 73 between the flighting 77 in the section corresponding to the re-thresher 78. The fingers do not protrude beyond the swept envelope of the flighting 77.

The housing of the re-thresher comprises a semi-cylindrical base 81 and a removable cover 82 which cooperate to enclose the crop channel and bound a passage through which the crop is guided. The base 81 has a profile that substantially corresponds to the tubular housing 83 of the longitudinal auger 66 both upstream and downstream.

The removable cover 82 is shown in more detail in Figure 7. A plurality of guide vanes 84 are fixed to the inside surface of the wall 82a. In order to accommodate the guide vanes 84, the external profile defined by the wall 82a is non-cyllndrica!. The cover 82 at each end is provided with peripheral mounting strips 85 with a plurality of holes 86 formed therein. The mounting strips engage against the inside faces of corresponding mounting plates 87 (Fig. 6) to support the cover in the longitudinal direction when in place. Bolts (not shown) are inserted through the holes 86 to secure the cover 82 in place.

The inner edges of guide vanes 84 present a profile which substantially conforms to the swept envelope (or volume) of the flighting elements 77 with minimal clearance therebetween. The interaction between the angled guide vanes 84 and flighting 77 conveys the crop forwardly through the re-thresher 78.

The effective increase in the cross sectional area of the crop passage experienced by the crop material in the re-thresher section 78 slows the flow. This allows the fingers 80, rotating with the flighting 77, to perform a threshing action on the tailings.

The (re-) threshed crop material is then passed into the downstream section of the longitudinal auger 66 and conveyed forwardly before being projected radially through a passage 89 into the crop processing apparatus 16 by a pair of paddles 90 attached to the downstream end of shaft 73. The returned material re-enters the crop processing apparatus 16 above the separator pan 44. As in known re-thresher apparatus, the re-threshed tailings then pass through the cleaning shoe 48 once again.

By providing an axial flow re-thresher of this construction in-line with the returns auger the number of components required is reduced when compared to known re- thresher apparatus thereby saving cost.

The re-thresher arrangement described lends itself well to being simply modified by the operator to disable the re-threshing action. This is particularly useful when harvesting maize for example. The cover 82 provided with the guide vanes 84 can be simpiy replaced with a plain 'non re-threshing' cover 92 without guide vanes shown in detail in Figure 8. The plain cover 92 comprises a wall section 92a which has an inner surface that presents a profile which substantially conforms to the swept envelope (or volume) of the flighting elements 77 with minimal clearance therebetween. In fact, the profile is substantially semi-cylindrical like the base 81. The crop material is therefore conveyed in the manner of a normal auger.

The plain cover 92 is also provided at each end with peripheral mounting strips 95 with a plurality of holes formed therein.

To disable the threshing action of the returns auger 66, the operator must simpiy replace the 're-threshing' cover 82 with the 'non re-threshing cover' 92 and remove the fingers 80. The longitudinal auger 66 then functions as a standard auger over its whole length.

Claims

1. A re-threshing system for a combine harvester, comprising a re-thresher housing which bounds a passage, a re-thresher auger having flighting elements mounted on a shaft arranged for rotation within the passage, the re-thresher housing comprising one of a first and second interchangeable cover wherein said first cover is employed in a re-threshing mode and comprises a plurality of guide vanes mounted on the inside thereof and having a profile which substantially conforms to the swept volume of the flighting elements wherein crop material is conveyed through the passage by contact between the guide vanes and flighting of the auger in rotation, and wherein said second cover is employed in a non re-threshing mode and comprises an inner wall surface that substantially conforms to the swept volume of the flighting elements wherein crop material is conveyed through the passage by contact between the inner wall surface and flighting of the auger in rotation, the system further comprising removable threshing fingers mounted on the shaft between the flighting when in the re-threshing mode.

2. A re-threshing system according to Claim 1 , wherein the wall of the second cover has a substantially semi-cylindrical profile.

3. A combine harvester comprising a primary threshing unit arranged to receive and thresh a harvested crop stream, a cleaning unit which receives tailings, chaff and grain removed from the straw in the threshed crop stream, the cleaning unit comprising means to separate tailings from the grain, and a re-threshing system according to Claim 1 or 2, to which the tailings are supplied.

4. A combine harvester according to Claim 3, wherein the passage forms part of a longer returns auger between an output of the cleaning unit output and an input of the cleaning unit.

5. A combine harvester according to Claim 4, wherein said re-thresher auger shares a common shaft with an adjacent portion of the returns auger.

6. A combine harvester according to Claim 5, wherein said flighting elements of the re-thresher are continuous with flighting elements of the returns auger provided on the common shaft.

7. A combine harvester according to any one of Claims 4, 5 or 6, wherein each of the first and second covers are provided with peripheral mounting strips secured at each axialiy-displaced end, each mounting strip comprising a plurality of holes to align with holes formed in corresponding mounting strips secured to respective ends of adjacent auger housing portions, bolts being inserted through the holes to secure the required cover in place.

8. A combine harvester according to any one of Claims 3 to 7, wherein the returns auger comprises a transverse portion which collects tailings from the cleaning unit, and a longitudinal portion which delivers crop material to said input side of the cleaning unit.

9. A combine harvester according to Claim 8, wherein the re-thresher housing is integrated with said longitudinal portion.