Abstract:
The invention provides an improved threshing and separating mechanism and method for a combine. The mechanism includes an elongated rotor mounted for rotation about a rotor axis within a rotor housing on the combine. The rotor has a threshing portion and a separating portion. The housing has a threshing section and a separating section corresponding to the threshing portion and the separating portion. The housing surrounds the rotor and is spaced from the rotor to form an annular space between the rotor and the housing for crop material to flow through in an axial crop flow direction from an inlet end of the housing to an outlet end of the housing. A rear portion of the rotor is tapered in a rearward direction to create an increased volume at the outlet of the rotor housing to prevent stagnation of flow of straw material in the transition of velocity between the housing outlet and the straw beater.

Description:
This application claims the benefit of U.S. provisional patent application Ser. No. 61/004,882 filed Nov. 29, 2007. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to rotors and housings for axial rotary agricultural combines. 
     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. 
     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. 
     Rotors have been provided for combines in a variety of configurations to optimize harvesting efficiency for a wide variety of crops and crop conditions. Examples are shown in U.S. Pat. Nos. 5,445,563 and 5,688,170 assigned to the assignee of the present application. These two patents both disclose rotary crop processing units having two or more sections. The relationship between the rotor axis and the housing axis varies from one section to the other. The rotor axis becomes increasingly offset from the housing axis in the crop flow direction from the housing inlet to the housing outlet. This is accomplished by abrupt transitions in the housing structure between sections where the housing shape changes. As the housing shape changes, the housing axis steps upward relative to the rotor axis and the gap between the rotor and the top of the housing increases at each step in the housing. 
     U.S. Pat. No. 7,070,498 describes a combine rotor having both infeed and threshing sections on a common frusto-conical portion of the rotor drum. The rotor in the infeed section is provided with helical infeed elements located on the fore-region of the frusto-conical portion of the drum. Immediately downstream from the infeed section, the threshing section is provided with a number of threshing elements. A portion of the threshing elements are attached to the aft-region of the frusto-conical portion of the drum, with the remaining portion being attached to the rearward cylindrical portion. 
     In such rotary combines, due to the shape and sizing of the housing covers, the rotor housing expands in steps as the material moves rearward. The first step is over the threshing area. The other expansion point is over the separator portion of the rotor. 
     The present inventors have recognized that when straw material exits from the rotor housing on a combine, there is typically some stagnation in the movement of the straw material as straw movement changes from a rotational direction to a linear direction into and through the discharge beater. This change in direction leads to loss of angular momentum and velocity which results in straw building up and congestion at the discharge point of the rotor housing. Extreme hesitation can result in a plug of the discharge of the rotor housing and the transition area, or in a failure of the surrounding housing and grates in the transition area. Current combines have a discharge paddle option to address material stagnation in this area. However, there is lacking a manner of fine-tuning the discharge paddles for proper material handoff to the discharge beater for different crops and conditions. 
     The present inventors have recognized that a need exists for providing a rotor housing for an axial rotary agricultural combine that provides for efficient and effective discharge of straw material, an increased wear life, and decreased damage to the straw. 
     SUMMARY OF THE INVENTION 
     The invention provides an improved threshing and separating mechanism for a combine. The mechanism includes an elongated rotor mounted for rotation about a rotor axis within a rotor housing on the combine. The rotor has a threshing portion and a separating portion. The housing has a threshing section and a separating section corresponding to the threshing portion and the separating portion. The housing surrounds the rotor and is spaced from the rotor to form an annular space between the rotor and the housing for crop material to flow through in an axial crop flow direction from an inlet end of the housing to an outlet end of the housing. 
     According to the preferred embodiment of the invention, a rear portion of the rotor tube is tapered in a rearward direction to create an increased volume at the outlet of the rotor housing to prevent stagnation of flow of straw material in the transition of velocity between the housing outlet and the straw beater. 
     The preferred embodiment of the invention provides a cone-shaped rear portion of the rotor tube to allow for more open volume between the rotor tube and the rotor housing to compensate for the material losing velocity and momentum at a rear of the rotor housing which will allow for better transition of crop flow from a rotational direction to a linear direction. 
     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 diagrammatic side view of a crop processing unit taken from the combine shown in  FIG. 1 ; 
         FIG. 3  is a perspective view of a cover for a crop processing unit of  FIG. 2 ; 
         FIG. 4  is a side view of the cover shown in  FIG. 3 ; 
         FIG. 5  is a bottom view of the cover shown in  FIG. 3 ; 
         FIG. 6  is a perspective bottom view of the cover shown in  FIG. 3 ; 
         FIG. 7  is a sectional view taken generally along line  7 - 7  of  FIG. 2 ; 
         FIG. 8  is a sectional view taken generally along line  8 - 8  of  FIG. 2 ; 
         FIG. 9  is a sectional view taken generally along line  9 - 9  of  FIG. 2 ; and 
         FIG. 10  is an enlarged fragmentary perspective view of a rear portion of the rotor shown in  FIG. 2 . 
     
    
    
     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 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 grain tank  28 . The clean grain in the tank  28  can be unloaded into a grain cart or truck by unloading auger  30 . 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. 
     As illustrated in  FIG. 2 , the axial crop processing unit  24  comprises a rotor housing  36  and a rotor  37  located inside the housing  36 . The front part of the rotor  37  and the rotor housing  36  define the infeed section  38  of the crop processing unit. Longitudinally downstream from the infeed section  38  are threshing section  39  and separating section  40 . The rotor  37  comprises a drum  100  to which crop processing elements for the infeed section, threshing section, and separating section are affixed. The drum  100  comprises a rearward cylindrical portion  102  and a forwardly extending frusto-conical portion  104 . 
     The rotor  37  shown in  FIG. 2  is similar to the rotor explained in more detail in U.S. Pat. No. 7,070,498, herein incorporated by reference. However, in contrast to the rotor shown in U.S. Pat. No. 7,070,498, the rotor  37  within the threshing section  39  includes a long tapered profile throughout the threshing section  39  without the cylindrical portion within the threshing section as described in U.S. Pat. No. 7,070,498. Alternatively, the rotor could be a rotor having the shape such as shown U.S. Pat. No. 5,688,170. The invention is useful with and encompasses all of these rotors. 
     The rotor  37  in the infeed section  38  is provided with helical infeed elements  42  located on the frusto-conical portion of the drum  100 . The helical infeed elements  42  engage harvested crop material received from the beater  20  and inlet transition section  22 . 
     In the threshing section  39  the rotor  37  is provided with a number of threshing elements  122  for threshing the harvested crop material received from the infeed section  38 . 
     The separating section  40  of the rotor includes outwardly projecting tines  126  similar to the tines disclosed in FIGS. 11 and 12 of U.S. Pat. No. 5,112,279, herein incorporated by reference. 
     The threshing section  39  of the rotor housing is provided with a concave  146  and the separating section  40  is provided with a grate  148 . Grain and chaff released from the crop materials falls through the concave  146  and the grate  148 . The concave and grate prevent the passage of crop material larger than grain or chaff from entering the cleaning system  26 . 
     The rotor is axially arranged in the combine and defines a central rotor axis RA. The rotor axis RA is a straight line passing through the infeed, threshing and separating portions of the rotor. 
     As seen in  FIG. 7 , the infeed section  38  of the rotor housing  36  is provided with a closed cover  162  and a closed bottom  164 . The cover  162  is provided with helical indexing vanes  165 . The cover and bottom are bolted to axial rails  166  and  168 . The forward portion of the closed bottom  164  is provided with an inlet transition section which is similar to one of those disclosed in U.S. Pat. Nos. 7,070,498 or 5,344,367, herein incorporated by reference. 
     The closed cover  162  of the infeed section  38  defines an infeed axis IA. The infeed axis IA is parallel to and substantially collinear with the rotor axis RA defined by the rotor. As such, the infeed portion of the rotor is substantially concentrically arranged in the infeed section  38  of the rotor housing as defined by the cover  162 . 
     As seen in  FIG. 8 , the threshing section  39  is provided with a closed threshing cover  172  having helical vanes  174 . The cover is bolted to axial rails  166  and  168 . The concave  146  is pivotally mounted to the frame of the combine below rail  168  at  175 . An adjustment assembly  176  for adjusting concave clearance is mounted to the frame of the combine below rail  166 . The concave  146  is provided with a closed extension  178 . 
     The threshing cover  172  defines a threshing axis TA that is parallel to the rotor axis RA. The threshing axis is located above the rotor axis RA. In addition, the threshing axis is slightly offset to the side of the rotor axis in a downstream direction. As such, the cover of the threshing section is eccentrically arranged relative to the threshing portion of the rotor. 
     The separating section  40  is provided with a separating cover  180  having helical vanes  182 . The cover is bolted to axial rails  166  and  168 . Grate  148  is also bolted to rails  166  and  168 . Grate  148  is similar to the grate disclosed in U.S. Pat. No. 4,875,891. 
     The separating cover  180  defines a separating axis SA that is parallel to the rotor axis RA. The separating axis is located above the rotor axis RA. In addition, the separating axis is offset to the side of the rotor axis in a downstream direction. As such, the cover of the separating section is eccentrically arranged relative to the separating portion of the rotor. 
     According to the preferred embodiment of the present invention, a frusto-conical transition section  200  is provided between the threshing section  39  and the separating section  40 , overlapping each section. 
     The transition section  200  includes a cover  210  having a substantially frusto-conical curvature. The cover  210  includes vanes  214   a ,  214   b . The vane  214   a  has a relatively wide width similar to the vanes  174  of the threshing section  39 . The vane  214   a  is substantially continuous with the last vane  182   a  of the separating section  40 . The vane  214   b  has a relatively wide width section  214   c  similar to the width of the vane  174  of the threshing section  39 , and a relatively thinner width section  214   d  similar to the width of the vane  182  of the separating section  40 . 
     Preferably, for smooth, energy-efficient flow, the cover  210  has a taper angle “G” that is substantially equal to a taper angle “H” of the rotor drum  100  within the threshing section  39  for the rotor shown in  FIG. 2 . 
     According to the present invention, the rotor tube  100  includes a taper portion or cone  220  at an outlet end of the processing unit  24  having an angle of taper “J.” The portion is located beneath a deflecting plate  180   a  in the separator cover  180 . Preferably the deflecting plate taper angle “K” is preferably substantially equal to the rotor angle “J.” 
     The taper portion  220  is shown in  FIG. 10 . The taper portion  220  is contiguous to a short reverse taper or radially expanding cone portion  230  that is adjacent to the end wall  232  ( FIG. 2 ) of the housing. The two tapered portions extend along a length of the tube  100  that is substantially in registry with the outlet opening  232 . Between the two tapered portions  220 ,  230  are two vanes  242 ,  244  that assist in the discharge of the straw material through a bottom directed outlet  246  ( FIG. 2 ) of the rotor housing that directs straw to the discharge beater  34 . 
     Each vane includes a welded on base portion  242   a ,  244   a  and an adjustable extending portion  242   b ,  244   b . Each base portion  242   a ,  244   a  has a stem portion  242   c ,  244   c  that fits within a cavity within a respective extending portion  242   b ,  244   b . The extending portions  242   b ,  244   b  can be pulled out a selective distance in the direction T from the base portions  242   a ,  244   a  and then two fasteners  250 ,  252  which penetrate holes in the extending portions  242   b ,  244   b  and which slide in slots in the stem portions  242   c ,  244   c  v can be tightened on the back side against the stem portions  242   c ,  244   c  to set the radial extent of the vanes  242 ,  244 . 
     Alternately, for each vane  242 ,  244 , the stem portion could not be in a cavity of the extending portion but could be on a back side of the extending portion and two fasteners could be used to either slide the extending portion evenly in the direction T with respect to the stem portion or to pivot the extending portions about one fastener to move only one end of the extending portion in the direction T. The fasteners are then tightened to set the radial extent of the extending portion. 
     Alternately, the extending portions are not adjustable per se but are replaceable with selectable extending portions of differing radial extents and the extending portions are merely fastened to the base portions. 
     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.