WO2012123478A1

WO2012123478A1 - Combine harvester re-threshing apparatus

Info

Publication number: WO2012123478A1
Application number: PCT/EP2012/054431
Authority: WO
Inventors: Thomas Bojsen
Original assignee: Agco A/S
Priority date: 2011-03-17
Filing date: 2012-03-14
Publication date: 2012-09-20
Also published as: GB201104487D0

Abstract

A combine harvester (10) comprises a primary threshing unit (26) arranged to receive and thresh a harvested crop stream and a cleaning unit (48) which receives tailings, chaff and grain removed from the straw in the threshed crop stream. The cleaning unit comprises a shaking sieve (56) which separates tailings from the grain. The combine further comprises a re-thresher (78) to which the tailings are supplied, the re-thresher comprising a housing (81, 82) which bounds a passage, a re-thresher auger having flighting elements (77) mounted on a shaft (73), a plurality of threshing fingers (80) mounted on the shaft between the flighting, and a plurality of guide vanes (84) mounted inside the passage on the inner surface of the housing. The inner surface of the guide vanes present a profile which substantially conforms to the cylindrical swept volume of the flighting elements. Crop material is conveyed through the re-thresher by contact between the guide vanes and flighting of the auger in rotation.

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.

Traditional re-threshing units are often bulky and occupy significant space on the machine. Furthermore, the re-threshing units require special components which require maintenance. United Kingdom patent GB-982,852 discloses an example of traditional re-threshing apparatus provided on a combine harvester. The re-threshing unit includes an annular housing within which a plurality of rotating paddles perform the threshing action upon the tailings. The paddles are arranged to project the crop stream radially outwardly exiting the housing in a gap in the circumferential wall.

It is an object of the invention to provide an improved re-thresher for a combine harvester.

It is another object of the invention to provide a re-thresher for a combine harvester which comprises fewer components than traditional re-threshers. In accordance with the present invention there is provided 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 a shaking sieve which separates tailings from the grain, and a re-thresher to which the tailings are supplied, the re-thresher comprising a housing which bounds a passage, a re- thresher auger having flighting elements mounted on a shaft producing a cylindrical swept envelope in rotation, a plurality of threshing fingers mounted on the shaft between the flighting, and a plurality of guide vanes mounted inside the passage on the inner surface of the housing and having a profile which substantially conforms to the cylindrical 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.

The combination of threshing fingers in between flighting elements with a number of co-operating guide vanes allows a conventional auger to accommodate a re- threshing section without significant modification. In other words, an axial flow re- thresher is provided. Advantageously, this consumes less space on the machine and requires fewer components than traditional re-threshers.

The invention involves the recognition that the additional threshing fingers disrupt the normal flow of crop material created by the auger. The discontinuous flow created by the fingers slows the passage of the crop material thus allowing the fingers to thresh the tailings.

To accommodate the guide vanes, the housing is enlarged in its sectional area which also disrupts the normal auger action. Axial conveyance is instead facilitated by the interaction between the guide vanes and the flighting.

The term 'flighting' can be used interchangeably throughout this specification with the term 'screw conveyor' or 'helical conveyor'. in a preferred arrangement the re-thresher is provided as part of a longer 'returns auger' which conveys said tailings to an input side of the cleaning unit to rejoin the threshed crop stream for re-processing. Therefore, the positioning of the 'in-line' re- thresher is not critical because its dimensions do not differ substantially from those of the overall returns auger thereby providing increased design freedom. In this preferred arrangement, said re-thresher auger preferably shares a common shaft with an adjacent portion of the returns auger thereby reducing the number of components required. Furthermore, said flighting elements of the re-thresher may be continuous with flighting elements of the returns auger provided on the common shaft.

The returns auger may comprise 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. The longitudinal portion typically extends forward at an incline to deliver the threshed tailings back to the main crop processing part of the combine.

The re-thresher is preferably integrated with said longitudinal portion which provides easy access for maintenance. In a preferred arrangement the re-thresher housing has a non-circular profile to accommodate said plurality of guide vanes mounted to the inside surface thereof, whereas the remaining part of the longitudinal portion comprises a housing of substantially circular profile.

The downstream end of the longitudinal portion may comprise a pair of paddles mounted to the shaft, the paddles being arranged to propel the re-threshed material into the cleaning unit through an orifice in a side panel of the combine. Conveniently, the paddles convey the re-threshed crop material at substantially 90 degrees to the auger direction with a minimum number of extra components. For example, no supplementary auger is required to provide this transverse projection of the material.

Preferably the threshing fingers are detachable which allows the apparatus to be converted so that no re-threshing action takes place.

The re-thresher housing may comprise a detachable portion which preferably has said guide vanes secured thereto. This enables the critical part of the re-thresher housing to be conveniently replaced with plain housing so that the crop material is conveyed by the flighting in the manner of a normal auger.

Further advantages of the invention will become apparent from reading the following 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 comer 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 axial 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 materia! 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 10 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 longitudina!ly-a!igned 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 fall 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 forward!y 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 materia! 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 collection 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 {or screw conveyor) 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 wali 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 radiaily/tangentiaiiy into the transition channel before it is collected by the flighting (or screw conveyor) 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 cylindrical 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-cylindrical. 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 cylindrical 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 paddies 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 simply 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 norma! 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 simply 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 combine harvester (10) comprising a primary threshing unit (26) arranged to receive and thresh a harvested crop stream, a cleaning unit (48) which receives tailings, chaff and grain removed from the straw in the threshed crop stream, the cleaning unit comprising a shaking sieve (56) which separates tailings from the grain, and a re-thresher (78) to which the tailings are supplied, the re-thresher comprising a housing (81 ,82) which bounds a passage, a re-thresher auger having flighting elements (77) mounted on a shaft (73) producing a cylindrical swept envelope in rotation, a plurality of threshing fingers (80) mounted on the shaft between the flighting (77), and a plurality of guide vanes (84) mounted inside the passage on the inner surface of the housing and having a profile which substantially conforms to the cylindrical 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.

2. A combine harvester according to Claim 1 , wherein the re-thresher is provided within a portion of a longer returns auger (66) which conveys said tailings to an input side of the cleaning unit to rejoin the threshed crop stream for re-processing.

3. A combine harvester according to Claim 2, wherein said re-thresher auger shares a common shaft (73) with an adjacent portion of the returns auger.

4. A combine harvester according to Claim 3, wherein said flighting elements of the re-thresher are continuous with flighting elements of the returns auger provided on the common shaft.

5. A combine harvester according to any one of Claims 2, 3 or 4, wherein the returns auger comprises a transverse portion (64) which collects tailings from the cleaning unit, and a longitudinal portion (66) which delivers crop material to said input side of the cleaning unit.

6. A combine harvester according to Claim 5, wherein the re-thresher (78) is integrated with said longitudinal portion (66).

7. A combine harvester according to Claim 6, wherein said re-thresher housing has a non-circular profile to accommodate said plurality of guide vanes (84) mounted to the inside surface (82a) thereof, whereas the remaining part of the longitudinal portion comprises a housing of substantially circular profile.

8. A combine harvester according to Claim 5, 6 or 7, wherein the downstream end of the longitudinal portion comprises a pair of paddles (90) mounted to the shaft, said paddles arranged to propel the re-threshed material into the cleaning unit through an orifice (89) in a side panel of the combine.

9. A combine harvester according to any preceding claim, wherein the threshing fingers are detachable.

10. A combine harvester according to any preceding claim, wherein the re- thresher housing comprises a detachable portion (82).

11. A combine harvester according to Claim 10, wherein the detachable portion has said guide vanes secured thereto.