Abstract:
A re-threshing apparatus and method for a combine harvester includes a rotor having threshing elements mounted thereon extending substantially radially. The rotor is rotationally mounted within a housing at least partially surrounding the rotor. The housing includes an inlet and an outlet. The housing has a wall portion with rasp bars extending toward the rotor. The wall portion is substantially solid, i.e., material re-threshed by the rasp bars remains within the housing until it moves through the housing outlet. The rotor and the housing are configured for tailings to be flung tangentially into the housing against the rasp bars and re-threshed between the threshing elements and the rasp bars within the housing.

Description:
This application claims the benefit of U.S. provisional patent application Ser. No. 61/005,005 filed on Nov. 29, 2007. 

   FIELD OF THE INVENTION 
   This invention relates in general to grain harvesting combines, and in particular to a system for re-threshing tailings from the crop cleaning section of a combine. 
   BACKGROUND OF THE INVENTION 
   Agricultural combines are large machines that harvest, thresh, separate and clean an agricultural crop. The resulting clean grain is stored in a grain tank located on the combine. The clean grain can then be transported from the grain tank to a truck, grain cart or other receiving bin by an unloading auger. 
   A grain harvesting combine has a header which cuts the crop and feeds it upward into a threshing and separating rotor within a housing having a perforated wall. The rotor rotates within the housing, passing grain within clearances between the rotor and perforated housing to thresh grain from the crop. 
   Rotary combines have one or two large rotors for threshing and separating the harvested crop material. In most rotary combines the rotor or rotors are arranged along the longitudinal axis of the machine. These rotors are provided with an infeed section for receiving harvested crop material, a threshing section for threshing the harvested crop material received from the infeed section and a separating section for freeing grain trapped in the threshed crop material received from the threshing section. Examples are shown in U.S. Pat. Nos. 5,445,563; 5,688,170 and 7,070,498, herein incorporated by reference. 
   The threshed grain falls onto a grain pan, and from the grain pan onto a set of upper and lower sieves. The sieves are oscillated, causing clean grain to fall through for collection. A blower blows air upward through the sieves, discharging chaff to the rear. Straw from the threshing chamber proceeds through a straw beater and out the rear of the combine. 
   The clean grain is collected and conveyed to the grain tank. Incompletely threshed grain will not proceed through the fingers of the sieves, yet is too heavy to be blown out the rear along with the chaff. This grain, called “tailings” or “returns” is often returned to the threshing and separating rotor for re-threshing. However, when tailings are returned to the rotor for re-threshing, under some grain conditions, called “white caps”, tailings will pass through the rotor yet again without the grain separating from the chaff. 
   Some prior art grain harvesting combines have dedicated re-threshing rotors for receiving tailings from the sieves, re-threshing the tailings, and passing the tailings back through the primary rotor for re-threshing. 
   U.S. Pat. No. 5,498,206 discloses a grain combine that includes a primary threshing rotor which rotates to thresh grain from crop, a sieve section for separating grain from chaff, a clean grain conveyor, a clean grain storage tank, and a re-threshing section for re-threshing tailings. The re-threshing section has a re-threshing rotor which receives the tailings from the sieve section. The re-threshing rotor extends completely across an end of the sieve section for rotating about an axis which extends in parallel to the end of the sieve section. The re-threshing rotor includes rasp bars which extend along the end of the sieve section for receiving the tailings and pressing the tailings against a re-threshing pan. Blowers are provided for removing loose chaff from the tailings in the re-threshing section. The re-threshed tailings, including clean grain separated from the tailings by re-threshing, are returned to the primary rotor for re-threshing. 
   The present inventors have recognized that some prior methods are limited in their ability to prevent grain damage in damage-sensitive crops. The present inventors have recognized that a need exists for a re-threshing system, method and apparatus that provided satisfactory yield, throughput, and minimal crop damage. 
   SUMMARY OF THE INVENTION 
   The invention provides a re-threshing apparatus for a combine harvester. The re-threshing apparatus includes a rotor having threshing elements mounted thereon extending substantially radially. The rotor is rotationally mounted within a housing at least partially surrounding the rotor. The housing includes an inlet and an outlet. The housing has a wall portion with rasp bars extending toward the rotor. The wall portion is substantially solid, i.e., material re-threshed by the rasp bars remains within the housing until it moves through the housing outlet. The rotor and the housing are configured for tailings to be re-threshed between the threshing elements and the rasp bars within the housing. 
   Depending on the crop the threshing elements of the rotor of the re-threshing apparatus can be rasp bars, or swept back bars, or serrated bars. 
   The wall portion is pivotally adjustable in a direction toward and away from the rotor to adjust the clearance between the rasp bars and the threshing elements. 
   Preferably, the rotor has a horizontal axis and an inlet arranged above the axis and an outlet below the axis and wherein the inlet is arranged to receive tailings flung through the inlet in a tangential direction with respect to the rotor. 
   The invention provides a re-threshing system and method that includes the above described re-threshing apparatus, a vertical elevator for transporting tailings from a cleaning section of the combine, a deflector for selectively directing tailings into the re-threshing apparatus or for directing tailings to bypass the re-threshing apparatus, and a delivery apparatus for distributing the re-threshed tailings within the cleaning section. 
   The invention provides a method of re-threshing tailings in a combine harvester. The housing has a stationary substantially solid wall portion with rasp bars extending therefrom. The housing has an inlet and an outlet. A rotor is located within the housing and has threshing elements extending therefrom. Tailings are thrown through the inlet into the housing. The rotor within the housing re-threshes the tailings between the threshing elements and the rasp bars. The step of throwing can be further defined by arranging the inlet to face the wall portion, and throwing tailings tangentially into the housing to impact the wall portion. The method can comprise the further step of adjusting clearance between the threshing elements and the rasp bars by selectively moving the wall portion. 
   Although the invention is illustrated as being used on a rotary combine, the present invention can be used on other combine types including conventional straw walker combines and hybrid combines having transverse threshing cylinders and rotary separators. 
   Numerous other advantages and features of the present invention will be become readily apparent from the following detailed description of the invention and the embodiments thereof, and from the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic side view of an agricultural combine the present invention; 
       FIG. 2  is a near side, fragmentary, perspective view of a crop cleaning system taken from the combine shown in  FIG. 1 ; 
       FIG. 3  is a far side, fragmentary, perspective view of a the crop cleaning system of  FIG. 2 ; 
       FIG. 4  is a near side, fragmentary, perspective view of a tailings re-threshing system taken from  FIG. 2 ; 
       FIG. 5  is a far side, enlarged, fragmentary perspective view of re-threshing rotor and housing taken from  FIG. 3 , with near side and far side covers removed to view the rotor; 
       FIG. 6A  is a diagrammatic cross-sectional view of a deflector in the deployed position; 
       FIG. 6B  is a diagrammatic cross-sectional view of the deflector of  FIG. 6A  rotated to a standby position; 
       FIG. 6C  is an enlarged sectional taken from  FIG. 6B ; 
       FIG. 7  is an enlarged fragmentary view of the deflector shown in  FIG. 6A  in the deployed position; 
       FIG. 8  is a far side, enlarged, fragmentary perspective view of re-threshing rotor and housing taken from  FIG. 3 , with near side and far side covers removed to view the rotor, and showing three different types of rotor threshing elements; 
       FIG. 9  is a far side, enlarged, fragmentary perspective view of re-threshing rotor and housing taken from  FIG. 3 , showing a top side of the housing, with the wall portion in an elevated position; and 
       FIG. 10  is a far side, enlarged, fragmentary perspective view of re-threshing rotor and housing taken from  FIG. 3 , showing a top side of the housing, with the wall portion in a lowered position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     FIG. 1  shows an agricultural combine  10  comprising a supporting structure  12  having ground engaging wheels  14  extending from the supporting structure. The operation of the combine is controlled from an operator&#39;s cab  15 . A harvesting platform  16  is used for harvesting a crop and directing it to a feederhouse  18 . The harvested crop is directed by the feederhouse  18  to a beater  20 . The beater directs the crop upwardly through an inlet transition section  22  to the axial crop processing unit  24 . 
   The crop processing unit  24  threshes and separates the harvested crop material. Grain and chaff fall through grates on the bottom of the unit  24  to the cleaning system  26 . The cleaning system  26  removes the chaff and directs the clean grain to a clean grain elevator (not shown). The clean grain elevator deposits the clean grain in a grain tank  28 . The clean grain in the tank  28  can be unloaded into a grain cart or truck by unloading auger  36 . Threshed and separated straw is discharged from the axial crop processing unit  24  through outlet  32  to discharge beater  34 . The discharge beater  34  in turn propels the straw out the rear of the combine. 
   Cleaned grain from the cleaning system  26  is collected in a clean grain pan  37  and fed by means of a grain auger  38  to an elevator (not shown) that conveys the grain into the grain tank  28 . 
   As illustrated in  FIG. 2 , the cleaning system  26  comprises a cleaning shoe  35  and a cleaning fan  30 . The cleaning shoe  35  comprises a frame  44  holding a return pan  45 , a chaffer sieve  46  and a lower, secondary sieve  48 . 
   The illustrated cleaning shoe  35  is a reciprocating shoe wherein the return pan  45 , the chaffer sieve  46 , and the secondary sieve  48  are reciprocated, oscillated or shaken to move crop material and to enhance separation through the sieves. 
   The chaffer  46  and the lower, secondary sieve  48  are arranged one above the other. The sieves  46 ,  48  oscillate or otherwise move during the operation of the cleaning shoe  35  in such a way that the harvested material separated by the threshing and separating device  24  is received on the side of the sieves  46 ,  48  which faces the threshing and separating device  24  and is additionally conveyed opposite the driving direction of the combine  10 . In order to achieve an optimal cleaning effect of the cleaning shoe  35 , the rotational speed of the blower and the width of the openings in the sieves  46 ,  48  can be varied. 
   Combine cleaning systems are disclosed in U.S. Pat. Nos. 4,531,528 and 6,672,957; and U.S. Pub. App. Nos. 2002/0128054 and 2005/0164755, all herein incorporated by reference 
     FIGS. 2-5  illustrate non-threshed crop portions or tailings are collected in a tailings pan  59  and moved by a tailings auger  60  to a circulating chain elevator  62  within a housing  63  which elevates the tailings to a discharge opening  64  by way of paddles  62   a  attached to an endless chain  62   b  ( FIG. 5 ). Such an elevator is known and is disclosed for example as elevator  54  in U.S. Pat. No. 5,497,605, herein incorporated by reference. As individual paddles  62   a  carried by the circulating chain turn over at a top of their vertical travel, the paddles  62   a  propel or fling the tailings into a re-threshing apparatus  66  that comprises a re-threshing rotor  68  driven in rotation within a re-threshing housing  72 . 
   Re-threshing rotor  68  rotates within re-threshing housing  72 . The housing  72  includes rasp bars  73  on an adjustable wall portion  74 . There are no perforations in the wall portion  74 . The rotor includes beating or threshing elements such as bars  75  that pass by the rasp bars  73 . Each rasp bar  73  has a finned area formed by a plurality of elements extending upward from a base portion. Rasp bars and other threshing elements are described in U.S. Pat. Nos. 4,964,838; 4,348,855; 6,036,598; 7,070,498; and 5,376,047, all herein incorporated by reference. 
   Gap  76  between the bars  75  and the rasp bars  73  can be selectively adjusted by moving wall  74  either towards or away from rotor  68 . Selecting gap  76  controls the yield and throughput for re-threshing a particular crop. Re-threshing yield is increased by decreasing gap  76  so that more clean grain is separated from tailings. However, decreasing gap  76  to increase yield decreases throughput, since clearances are reduced. Thus, gap  76  should be set for particular crops to counterbalance throughput verses yield for re-threshing tailings. 
   A deflector  84  is provided within the housing  72  which is effective to cause tailings to bypass the re-threshing rotor  68  and re-threshing housing  72 . The deflector  84  is shown in a first, standby position marked  84   a  (shown dashed) and a second, deployed position marked  84   b . With the deflector  84  in the position marked  84   a , re-threshing crop flow is thrown by the paddles of elevator  62  through the discharge opening  64  in a tangential direction indicated by arrow marked “A” into the re-threshing housing  72 . With the deflector  84  in position marked  84   b , bypass crop flow is thrown downward through a vertical bypass path  91  and into a discharge chute  92  in the direction indicated by arrow marked “B.” 
   The rotor  68  is driven on one axial end by a pulley or sprocket  93  driven by a belt or chain  93   a  driven by the equipment drive power system of the combine on a near side of the housing  72 . 
   The other axial end of the rotor  68  drives a pulley or sprocket  94  that circulates a belt or chain  94   a , that drives a pulley or sprocket  95  that drives the circulating chain  62   b  of the elevator  62  ( FIG. 3 ). 
   Re-threshing crop flow “A” and/or bypass crop flow “B” exits the housing  72  downward through the discharge chute  92  to an auger  96 . The auger  96  includes a tubular auger housing  98  and an auger screw  100 . 
   The tubular auger housing  98  is arranged transversely across the cleaning system  26 , particularly over the return pan  45 . The auger housing includes a tapered slot formation  120  that has a far side small width  122  increasing to a near side maximum width  124 . In this way, the tailings conveyed by the auger screw  100  from the chute  92  will be evenly distributed from out of the slot formation  120  transversely across the return pan. 
   The auger screw  100  is driven in rotation by a sprocket or pulley  140  located on its far side end that is driven by a belt or chain (not shown) from the equipment drive power system of the combine. 
     FIGS. 6A-7  illustrate the deflector  84  in more detail. 
   As shown in  FIG. 6A , the deflector  84  is in the deployed position  84   b . The deflector  84  includes an arcuate deflecting plate  200  that smoothly deflects tailings thrown in a horizontal direction to a downward direction into the bypass path  91 . The plate  200  is formed with a vertical support plate  204  having a horizontal lip  206 . The lip  206  rests on, and substantially seals against, a stationary housing plate  210  of the housing  72 . The plate  200  also includes an opposite end lip  212 . An inclined brace plate  216  is connected at one end to the plate  200  and at an opposite end to a hinge assembly  220  that is secured to the housing  72 . The hinge assembly  220  allows the deflector  84  to pivot between the two positions shown in  FIGS. 6A and 6B . As shown in  FIG. 7 , the plates  200 ,  216  are connected together by sideplates  226 ,  228  to create a rigid assembly. A lift bar  232  penetrates through the sideplates  226 ,  228  and is connected atone end to a bracket  234 . The deflector  84  can be pivoted by force exerted on the bracket  234 . In this regard, a lever  240  (shown schematically only) can be pivotally mounted to the housing  72  and pivoted about a pivot point  242  with respect to the housing  72  to pivot the deflector  84 . 
   When the deflector  84  is pivoted to the standby position of  FIG. 6B  the lip  212  substantially seals against a bottom of the wall  210  as shown in  FIG. 6C . The lever  240  can be fixed to fix the deflector at a desired pivotal position corresponding to either of the positions shown in  FIGS. 6A and 6B  by bolting the lever to the housing at the desired position, or by providing some other releasable fixation means. 
   The plates  200 ,  204 ,  206 ,  212 ,  216 ,  226 ,  228  are typically metal plates that can be formed and assembled using fasteners, bending, rivets, welding or other methods known to those skilled in the art. 
     FIG. 8  illustrates three possible bars  75  that can be used on the rotor  68 . Typically, only one type would be used on the rotor  68  but three different types are shown for illustration. However, it is also encompassed by the present invention to use more than one type of bar  75  on a single rotor  68 . 
   A rasp bar  75   a  is illustrated having a mounting portion  302  that holds rasp elements  304 . The rasp elements  304  are structured similarly to the rasp bar  73 . The each rasp element has a finned area formed by a plurality of elements extending upward from a base portion. 
   This rasp bar  75   a  would be useful for rasp-on-rasp type threshing for difficult to thresh crops. 
   A serrated flat bar or comb bar  75   b  is illustrated and is particularly suitable for wet material movement. 
   A sweptback bar  75   c  is illustrated and is suitable for satisfactory material movement and threshing. It is suitable as a general-purpose bar. 
   As illustrated in  FIGS. 5 ,  9  and  10 , the wall portion  74  is hinged by a hinge assembly  308  to a stationary portion  312  of the housing  72  to be pivotable with respect to the stationary portion  312 . The wall portion  74  comprises a plurality of flat plates  320  connected together to approximate a curved surface. Each flat plate  320  mounts a rasp bar  73  on an underside thereof. 
   As shown in  FIGS. 9 and 10 , the wall portion  74  is supported by the hinge assembly  308  at one end and by a crank bar  326  near an opposite end. The crank bar  326  includes an offset portion  330  that penetrates through two brackets  336 ,  338  that are fastened to reinforcing ribs  340 ,  342  that connect the last three flat plates  320 . 
   End portions  346 ,  348  of the crank bar  326  are each rotationally fixed to a lever  360 , one on each side of the housing  72  (only one being visible in the figures the other one being mirror image identical in structure and operation). The levers  360  are each fixed to a stationary bracket  370  (only one being visible in the figures the other one being mirror image identical in structure and operation) by a bolt  374  and a corresponding nut (not visible), the bolt being slidable through a slot  376  in the stationary bracket  370  when the nut is loosened. 
     FIG. 9  shows the wall portion  74  pivoted away from the rotor  68  a maximum amount. The levers  360  (the opposite side lever not visible) have been pivoted together clockwise in the rotary direction R and the offset portion  330  of the crank bar  326  has been raised by rotation of the crank bar  326 , to pivot the wall portion  74  up via the brackets  336 ,  338  and the ribs  340 ,  342 . After pivoting the wall portion  74  the nut is tightened on the bolt  374  to fix the wall portion  74  in position. 
     FIG. 10  shows the wall portion  74  pivoted toward from the rotor  68  a maximum amount. The levers  360  (an opposite side lever not visible) have been pivoted together counterclockwise in the rotary direction S and the offset portion  330  of the crank bar  326  has been lowered by rotation of the crank bar  326 , to pivot the wall portion  74  down via the brackets  336 ,  338  and the ribs  340 ,  342 . After pivoting the wall portion  74  the nut is tightened on the bolt  374  to fix the wall portion  74  in position. 
   According to the invention there are no holes in the wall portion  74  for grain to pass through. The grain, once rubbed against the rasp bars  73  falls back into the housing  72  due to gravity and momentum, particularly because of the positioning of the rasp bars at an elevated position regarding the outlet of the housing  72 . The bars  75  move tailings against the rasp bar  73  and re-threshing is accomplished by both the rubbing action between the bars  75  and the rasp bars  73  and a throwing action of the bars  75  throwing material against the uneven surface of the rasp bars  73 , with the assistance of gravity as the tailings fall from the rasp bars  73 . 
   From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.