Abstract:
A tailings conveyor includes a housing for receiving tailings from the cleaning system, a first rotary impeller having threshing portions rotatable at a first speed for accelerating and propelling tailings along a predetermined path in the housing, and at least one additional impeller having threshing portions rotatable at a greater rotational speed for further accelerating and propelling the tailings along the path, such that the tailings collide with others of the tailings and against and along an interior surface of the housing for threshing the tailings, such that the tailings are progressively accelerated and threshed as they are conveyed through the conveyor. At least the first and second impellers are located in closely spaced relation for defining a threshing area within the housing and preventing build up of tailings that could lead to clogging and loss of efficiency and tailings throughput.

Description:
[0001]     This application is a Continuation-In-Part of U.S. patent application Ser. No. 10/340,263, filed Jan. 10, 2003. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates generally to an agricultural combine, and more particularly, to a tailings conveyor and method of operation thereof for conveying tailings from a cleaning system of the combine, which conveyor includes at least two rotary impellers which are sequentially positioned and rotated at progressively faster speeds for propelling tailings along a predetermined path through a housing of the conveyor and simultaneously threshing the tailings.  
       BACKGROUND ART  
       [0003]     Typically, an agricultural harvesting machine such as a combine gathers crop from a field and transports the crop by means of a feeder house to a threshing and separating device located inside the combine. Generally, threshing refers to removing grain, beans, seeds or kernels, hereinafter referred to as just grain, which are desired to be collected, from husks, cobs, pods, stems, hulls and other portions of the plants being harvested, which are to be discarded. The threshing and separating device delivers the crop to the cleaning system of the combine, which includes a plurality of sieves. An upper sieve allows clean grain and some material other than grain (MOG) to fall through it, and a lower sieve is adjusted so that only clean grain is allowed to pass through it. The material including the clean grain and MOG that falls through the upper sieve, but does not pass through the lower sieve, is called tailings. In many cases the MOG will include pods, husks, or cob fragments or hulls that contain or hold grain, and thus it is desired for this material to be threshed and/or cleaned again to recover this grain.  
         [0004]     Prior methods accomplish the threshing and/or cleaning of the tailings by conveying them to one side of the combine with an auger. The tailings are then carried by a conveyor, typically a paddle and chain conveyor, back to the combine threshing mechanism. Some combines have used a rethreshing device which is separate from the threshing system which helps save capacity on the threshing system by rethreshing the tailings separately from new crop coming into the combine. The auger feeds material into the rethreshing device and then the material is conveyed back to the cleaning system. Both single impeller/blowers and augers have been used to convey this material back to the cleaning system. These rethreshing devices are usually convertible, enabling the operator to manipulate the machine to be more or less aggressive, depending on the vulnerability of the grain to damage, during processing.  
         [0005]     Prior methods for conveying the tailings material are inefficient in terms of throughput capacity and power consumption. Some known embodiments have resulted in large conveying devices that tend to limit access to both the combine and the conveying device for maintenance and conversion.  
         [0006]     Therefore, what is needed is a more efficient means for conveying tailings, which overcomes many of the limitations and shortcomings set forth above, is more versatile, and can be adapted for providing a desired threshing function as the tailings are conveyed thereby.  
       SUMMARY OF THE INVENTION  
       [0007]     What is disclosed is a tailings conveyor which threshes tailings as they are conveyed therethrough, so as to provide one or more of the capabilities and overcome one or more of the limitations and shortcomings set forth above.  
         [0008]     According to one aspect of the invention, the tailings conveyor includes a housing including an interior cavity, an inlet opening connecting with the cavity for receiving tailings from the cleaning system into the cavity, and an outlet opening for discharging the tailings from the cavity. The conveyor includes a first rotary impeller supported for rotation about a first rotational axis in the cavity at a position adjacent to the inlet opening and an interior surface of the housing, the first impeller including a plurality of blades extending radially outwardly from a first hub to radial outer threshing portions or tips of the blades, and a first drive connected in driving relation to the first hub for rotating the first impeller such that the threshing portions or tips thereof will rotate at a predetermined first rotational speed or within a first rotational speed range. In operation, during the rotation, the threshing portions will accelerate and propel tailings received into the interior along a predetermined path therein, including against others of the tailings and against and along the interior surface for threshing the tailings. The conveyor includes a second rotary impeller supported for rotational about a second rotational axis in the cavity at a location downstream along the path from the first impeller, the second impeller including a plurality of blades extending radially outwardly from a second hub to radial outer threshing portions or tips of the blades, and a second drive connected in driving relation to the second hub for rotating the second impeller such that the threshing portions or tips will rotate at a predetermined second rotational speed greater than the first rotational speed. As a result of the greater rotational speed of the second impeller, the second impeller will further accelerate and propel the tailings against others of the tailings and against and along the interior surface and along the path for threshing the tailings, such that the tailings are progressively accelerated relative to their initial speed and are threshed as they are conveyed through the conveyor.  
         [0009]     According to another preferred aspect of the invention, the first and second impellers are positioned in such that the radial outer threshing portions thereof counter rotate in closely spaced relation in a portion of the interior cavity so as to define a boundary of a conveying region of the cavity through which a portion of the predetermined path extends and in which it is desired for the tailings to be substantially contained. This is to prevent or significantly reduce the occurrence of build up of tailings in the region between the impellers which could lead to clogging and a reduction in the efficiency and throughput capacity of the conveyor.  
         [0010]     According to another preferred aspect of the invention, the conveyor includes a third rotary impeller supported for rotation about a third rotational axis in the cavity at a location downstream along the path from the first and second impellers, the third impeller including a plurality of blades extending radially outwardly from a third hub to radial outer threshing portions, and a third drive connected in driving relation to the third hub for rotating the third impeller such that the threshing portions thereof will rotate at a predetermined third rotational speed greater than the second rotational speed and will further accelerate and propel the tailings against others of the tailings and against and along the interior surface and along the path for further threshing the tailings, and outwardly from the housing through the outlet opening. Alternatively, in the absence of the third impeller, the second impeller can be positioned for discharging the tailings through the outlet opening.  
         [0011]     By rotating the radial outer threshing portions or tips of the blades of two or more successive impellers at progressively greater rotational speeds, that is, rotating the tips of the blades of successive ones of the impellers at speeds faster than the previous ones, the tailings are progressively accelerated. This, in combination with propelling the tailings in the turbulent manner, and by propelling the tailings against and along the interior surface of the housing and into the path of rotation of the next successive one of the impellers, has been found to reduce hesitation in the movement of the tailings through the conveyor while providing sufficient movements and collisions of the tailings for causing separation of grain, beans, seeds, kernels, and the like grain, which are desired to be collected, from husks, cobs, pods, stems, hulls and other portions of the plants being harvested. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a simplified side view illustrating an embodiment of the major components of an agricultural harvesting machine.  
         [0013]      FIG. 2  is a more detailed view of the harvesting machine of  FIG. 1  depicting an embodiment of a tailings conveyor according to the invention within the machine with a front cover of the conveyor removed to show internal aspects thereof.  
         [0014]      FIG. 3  is a perspective view of an embodiment of the conveyor of  FIG. 2  in association with a feed auger of the machine for feeding tailings to the conveyor.  
         [0015]      FIG. 4  is a simplified perspective view of the tailings conveyor of  FIG. 2 .  
         [0016]      FIG. 5  is a simplified perspective view of the tailings conveyor taken along line  5 - 5  of  FIG. 4 .  
         [0017]      FIG. 6  is a frontal view of the tailings conveyor housing of  FIG. 2  with the front cover removed and illustrating impellers of the conveyor for propelling tailings through the conveyor in a turbulent manner for threshing the tailings.  
         [0018]      FIG. 7  is a simplified schematic frontal view of one belt drive arrangement for the impellers of the tailings conveyor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     Referring to  FIG. 1 , an agricultural harvesting machine  10 , incorporating the principles of the instant invention, has a header  12 , a reel  14 , and a feeder  16 . Crop material is collected by header  12  and reel  14  and taken into agricultural harvesting machine  10  through feeder  16  in a conventional manner.  
         [0020]     A threshing assembly  18  includes a rotor  20  and a perforated housing  22 . Rotor  20  is rotated within perforated housing  22 . Crop is received from feeder  16  and is passed through clearances between rotor  20  and perforated housing  22  to thresh grain. Grain which is threshed in the clearances between housing  22  and rotor  20  falls through the perforations in housing  22  and is transported to a cleaning system  24  including a chaffer sieve  26  and a shoe sieve  28 . Chaffer sieve  26  and shoe sieve  28  are members that oscillate back and forth. Sieves  26  and  28  have a plurality of apertures for allowing the properly threshed grain to fall through. A blower  30  blows air through sieves  26  and  28  and out the rear of agricultural harvesting machine  10 . Chaff will be blown outward along with the air. The clean grain falls through sieves  26  and  28  onto an inclined plane  32 . Clean grain travels along plane  32  and then through a grain elevator  34 , to a grain storage area  36 .  
         [0021]     Grain and material other than grain (MOG) which can still contain or hold a significant amount of grain, and which is too heavy to become air borne and falls through chaffer sieve  26  but does not pass through shoe sieve  28  is commonly known as tailings. Tailings end up on a plane  38  and are rethreshed and conveyed in a tailings conveyor  40  and discharged from tailings conveyor  40  onto chaffer sieve  26 .  
         [0022]     As in best seen in  FIG. 2-6 , tailings conveyor  40  includes a housing  42  including an interior portion  43 ; a first opening  44  communicating with interior portion  43 ; a first rotary impeller  46  and a second rotary impeller  48  located in interior portion  43 ; and a second opening  50  communicating with interior  43  and a conduit  52 . A third impeller  72  is located in conduit  52 . The first and second impellers  46  and  48  are each rotated in predetermined rotational directions A on shafts  58  and  51 , respectively, about substantially parallel rotational axes C and D extending longitudinally through the centers of shafts  58  and  51 , respectively. The third impeller  72  may rotate in the opposite direction or as alternative in the same direction as the bottom two impellers  46  and  48 .  
         [0023]     Housing  42  receives the tailings through first opening  44  by means of a rotatable auger  54 , depicted in  FIG. 3 . Auger  54 , as shown  FIGS. 4, 5  and  6 , rotates about rotational axis C on a shaft  56  coaxial with shaft  58  for moving the tailings toward tailings conveyor  40 , such that the tailings will be discharged by auger  54  through first opening  44  into interior portion  43  of housing  42  in a position to be propelled by rotating first impeller  46  through interior portion  43  to second impeller  48 . As an alternative, first opening  44  can be offset from the shaft  58 , such as depicted at  44   a  in  FIG. 6 , so that, for instance, tailings  60  are delivered into housing  42  at a lower location or more in the vicinity of the radial outer portion of first impeller  46 .  
         [0024]     First impeller  46 , second impeller  48 , and third impeller  72  each include a plurality of blades  47  extending generally radially outwardly relative to the rotational axis of the respective impeller. Each of the blades  47  is preferably curved or arcuate so as to have a concave surface  47   a  facing oppositely of the rotational direction A, and a convex surface  47   b  facing forwardly in or toward the rotational direction A. The radial outer ends of blades  47  of first impeller  46  are preferably swept back relative to the rotational direction A, as best shown in  FIG. 6 . The radial outer ends of blades  47  of second impeller  48  preferably extend more directly radially outwardly.  
         [0025]     The impellers  46 ,  48  and the second opening  50  are preferably radially in-line or aligned, such that tailings  60  which enter housing  42  at opening  44 , or  44   a , are propelled in rotational direction A by first impeller  46  along a predetermined path of movement along and defined largely by a radially inwardly facing threshing surface  64   a  of a first threshing plate  64 , and into the path of rotation of radially adjacent second impeller  48 , as denoted by large arrow B. Second impeller  48  will then propel tailings  60  in direction A further along a radially inwardly facing threshing surface  68   a  of a second threshing plate  68 , and through second opening  50  into conduit  52  into the path of rotation of third impeller  72 , as also denoted by a large arrow B. Third impeller  72  will then propel tailings  60  along the path of movement through conduit  52 , again as denoted by a large arrow B, so as to exit through a discharge outlet  62 , so as to be spread over a predetermined region of chaffer sieve  26 , or another location if desired. In interior portion  43  of housing  42 , a radially inwardly facing common housing wall  66  guides and enhances the radial direction of travel of tailings  60  from first impeller  46  to second impeller  48 . In conduit  52 , a third threshing plate  80  can be provided having a radially inwardly facing threshing surface (not shown) for facilitating threshing by third impeller  72 , and for guiding the tailings flow to conduit  52 .  
         [0026]     The preferred rotational direction A for both of impellers  46  and  48  is clockwise. The preferred rotation of impeller  72  is counterclockwise, however clockwise will also suffice. The curved or arcuate or swept back shape of blades  47  of impeller  46  has been found to cause a more aggressive threshing of tailings  60  and forces the tailings  60  to the radially outer portion of the blades  47  faster, which has been found to increase conveying capacity. Threshing plate surfaces  64   a ,  68   a  and  80  may each have a rough surface texture or smooth, and/or can include elements such as raised protuberances and the like, for imparting a desired turbulence to the tailings flow, for performing a desired threshing function, as discussed in more detail below.  
         [0027]     Impellers  46 ,  48  and  72  each includes a mounting portion  82  which is preferably a hub, mountable to a rotatable member, such as shaft  58  of conveyor  40  in the instance of impeller  46 , for rotation with the rotatable member in a predetermined rotational direction, such as direction A, about a rotational axis, such as axis C, as best shown in  FIG. 6 . Each impeller  46 ,  48  and  72  includes a plurality of blades  47 , preferably four in number, which extend generally radially outwardly from mounting portion  82  at equally spaced locations around the rotational axis. As noted before, each blade  47  includes a surface  47   a  facing in a direction opposite the rotational direction, and a surface  47   b  facing in the rotational direction.  
         [0028]     Surface  47   b  of each blade  47  of impellers  46 ,  48  and  72  includes a radially outer threshing portion  84  facing in rotational direction A and terminating at a radially outermost tip portion  86 , and a tailings deflecting portion  88  which generally encompasses the convex region of the blade between threshing portion  84  and mounting portion  82 . In operation, as tailings  60  are inducted into interior portion  43  of housing  42  through opening  44  or  44   a , elements of the tailings, which will generally include some individual loose grain, grain partially or fully contained in pods or pod fragments, small straw pieces, pod fragments, and other plant fragments, will be impacted by surface  47   b  and propelled or driven in direction A. In this context, it has been found that as a result of the convex shape of deflecting portion  88  of each blade, tailings  60  impacted thereby will be propelled or driven generally tangentially radially outwardly and forwardly, as illustrated by arrows H in  FIG. 6 , into the path of threshing portions  84  of blades  47 . This will occur in a relatively turbulent manner, such that the individual tailings will collide randomly with each other and with threshing portion  84 , and also with threshing surface  64   a . As a result, at least some of the pods and pod fragments containing grain will be broken open to release the grain therefrom, for eventual cleaning or separation from the MOG in the cleaning system.  
         [0029]     To facilitate or accentuate this threshing action, each blade  47  has a predetermined radial extent as measured from the center of mounting portion  82  to tip portion  86  of the blade, which is a predetermined amount less than a predetermined minimum radial distance to the corresponding threshing surface  64   a  or  68   a , as illustrated by distance F from axis C to threshing surface  64   a  ( FIG. 6 ). As a result, the spacing between tip portions  86  of the blades and the threshing surface  64   a  or  68   a  can be controlled, as desired or required for a particular application. In this regard a wide range of spacings can be utilized. For instance, a non-limiting representative range of spacings is from as little as about 1 mm to 2.5 mm or larger, it being mainly desired that the tailings will be carried or driven by tip portion  86  over surface  64   a  or  68   a  in a turbulent manner and as a result will roll and tumble along surface  64   a  and be otherwise agitated so as to collide with the other tailings and threshing surfaces  64   a ,  68   a  and  84 , and tip portion  86 , such that at least some portion of remaining intact pods and other grain holding plant fragments will be broken open to release the grain therefrom.  
         [0030]     As another result of the movement and action set forth above, some of the tailings, which have some abrasive properties, will pass and/or be dragged through the space between surface  64   a  or  68   a  and tip portions  86 , such that wear of the affected surfaces will occur with use, particularly surface  64   a  and the surfaces of tip portions  86  facing in direction A. To maintain the radial length of blades  47  and provide desired impeller effective life under anticipated wear conditions, tip portions  86  each preferably have an enhanced thickness or extent in direction A which is greater compared to the extent of most other portions of blade  47  in direction A. As a result, even as tip portions  86  wears or abrades away, the radial extent of blade  47  will remain substantially the same. Also, threshing plate  64 , or at least the portion thereof including threshing surface  64   a , is preferably removable and replaceable and/or reversible.  
         [0031]     Here, it should be noted that by virtue of the convex shape of blades  47  of impeller  46  in the region of tailings deflecting portions  88 , threshing portions  84  and tips  86  are swept back relative to direction A. This, in combination with threshing surface  64   a , defines a space  90  forwardly of threshing portion  84  of each blade  47  in direction A ( FIG. 6 ) where much of the above discussed turbulence and resultant threshing action takes place. The swept back configuration also facilitates accelerating and shedding of the tailings off of tip portions  86  of the blades after passing surface  64   a , so as to be propelled toward second impeller  48 .  
         [0032]     In contrast to the shape of blades  47  of impeller  46 , blades  47  of second impeller  48 , although having a convex shape deflecting portion  88 , preferably have a threshing portion  84  and tip portion  86  which are substantially directly radially outwardly extending, that is, which is not, or much less, swept back relative to deflecting portion  88 , but instead is essentially perpendicular in respect to rotational direction A. As a result, blades  47  of impeller  48  will shed tailings to a lesser extent, compared to swept back blades  47  of impeller  46 . This provides even greater acceleration of the tailings. Blades  47  of impeller  48  also have a greater length, such that impeller  48  has a greater diametrical extent compared to impeller  46 . As a result, for a given rotational speed, threshing portions  84  and tip portions  86  of impeller  48  will move faster than the corresponding portions of impeller  46 , which will provide greater acceleration of tailings.  
         [0033]     As another feature for facilitating flow of the tailings along path B from impeller  46  to impeller  48 , those impellers are positioned one relative to the other such that only a minimal space, denoted at H in  FIGS. 2, 5  and  6 , exists between tip portions  86  of the impellers, effectively defining a threshing region to the left of impellers  46  and  48  in  FIG. 6 , generally including and in proximity to large arrows B. An exemplary range of values of space H is from about 6 to 50 mm. An advantage of such a small space H is that as the close tip portions  86  of impellers  46  and  48  counter rotate, only a minimal amount of tailings are allowed to pass from the threshing region therebetween, such that the tailings have less of a tendency to collect or mass around the radial outer periphery of impellers  46  and  48 .  
         [0034]     Additionally, impeller  48  is preferably rotated at a faster rotational speed than impeller  46 , and impeller  72  is preferably rotated at a faster rotational speed than both impeller  46  and impeller  48 . As a result of this progression of faster rotational speeds in combination with the other features of impellers  46 ,  48  and  72 , particularly the closely spaced relationship between tip portions  86  of impellers  46  and  48  (space H), tailings  60  are continually or progressively accelerated along path B through interior  43  and conduit  52 , with little or no hesitation or stalling in the transition regions between the impellers, generally in the location of the large arrows B in  FIG. 6 .  
         [0035]     Referring also to  FIG. 7 , a representative drive arrangement  92  for rotatably driving shafts  58  and  51  for rotating impellers  46  and  48  ( FIGS. 2, 4 ,  5  and  6 ), and for rotating an input shaft  94  of an angle gear box  96  ( FIGS. 4 and 6 ) connected in rotatably driving relation to impeller  72 , is shown. Drive arrangement  92  includes a serpentine belt  98  which encircles an input pulley  100  and pulleys  102 ,  104  and  106  connected to shafts  94 ,  51  and  58 , respectively. Input pulley  100  is connectable in the well known manner in rotatably driven relation, to a rotatable power source such as a fluid motor, an electric motor, an engine of combine  10 , transmission, or the like (not shown). Pulley  106  is larger in diameter than pulley  104 , and pulley  104  is larger in diameter than pulley  102 , such that for a given rotational speed of input pulley  100 , impeller  72  will rotate faster than impeller  48 , and impeller  48  will rotate faster than impeller  46 , to provide the desired progression of rotational speeds.  
         [0036]     Here, it should be noted that third impeller  72  will preferably be constructed the same and operate essentially the same as first impeller  46 , although it should also be noted that impellers  48  and  72  could be constructed differently, as required for providing different operating characteristics, as desired or required.  
         [0037]     Although illustrative embodiments have been shown and described, a wide range of modification, change and substitution is contemplated in the foregoing disclosure and in some instances, some features of the embodiment may be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the embodiments disclosed herein.