Abstract:
An improved cutter assembly for use with a header of an agricultural harvester is provided. The assembly includes a pair of oppositely directed knife blades or cutter bars and a center knife drive. A crank shaft drives both knife blades in linear reciprocating paths with no fore and aft movement. As a consequence, harmful fore and aft vibration is eliminated. The assembly is simple and durable in design, less susceptible to vibration-induced wear and tear, and comparatively simple to manufacture and repair.

Description:
BACKGROUND 
       [0001]    The subject application relates generally to headers for agricultural harvesters. In particular, the subject application relates to a header including an improved harvester cutter assembly for driving oppositely directed knife blades in linear reciprocating or oscillating fashion. 
         [0002]    Agricultural harvesters such as combine harvesters are well known apparatuses for harvesting grain crops. An agricultural harvester is typically a self-propelled vehicle which includes a feederhouse and mechanisms downstream of the feederhouse for separating grain from other crop material. A header is attached to the front of the harvester and includes mechanisms for cutting crop, gathering crop and delivering crop to the harvester&#39;s feederhouse. A typical crop cutter includes a stationary knife and a moving knife which together act as shears that cut crop near the ground. After cutting, the crop is gathered, e.g., by a harvesting reel which feeds the cut crop to a conveyor system that transports the cut crop to the harvester&#39;s feederhouse. 
         [0003]    Typical agricultural harvester cutter assemblies include a pair of oppositely directed knife blades each of which are formed from a plurality of sickle sections that are secured to a knife back. Each knife back, in turn, is connected to a knife drive. In conventional cutter assemblies the knife blades are pivotably connected to the knife drives whereby the knife drives propel the knife blades through a non-linear, arc-like path of motion. In traversing the arc, the knife blades move not only from side to side (i.e., transverse to the direction of movement of the harvester) but also fore and aft (i.e., in the direction of movement of the harvester). The fore and aft motion of the knife blades results in forward and rearward vibration being introduced into the cutter assemblies which adds additional stresses on the knife blades and detrimentally affects the service life of the knife drives. 
         [0004]    In addition, the sickle knife drives of current agricultural harvesters are complex in construction with many moving parts including multiple crank shafts and gears. In a typical arrangement, at least one crank shaft and gear is required to drive each knife blade and the interaction of these components must be carefully coordinated in order to move the knife blades in synchronicity. The complexity of such knife drives renders them difficult and costly to manufacture and repair while increasing their susceptibility to failure, which can deleteriously impact harvesting productivity. 
       BRIEF SUMMARY 
       [0005]    In accordance with a first aspect, the subject application provides a cutter assembly for an agricultural harvester header. The cutter assembly addresses the problems of vibration and undue design complexity by virtue of a robust yet simple construction. The subject application is directed to a cutter assembly having a sickle knife drive that uses a single crank shaft and flywheel to linearly oscillate or reciprocate a pair of sickle knife blades or cutter bars in simple harmonic motion. The knife blades or cutter bars are coaxially arranged and oppositely directed, and their linear reciprocation in a side to side direction eliminates fore and aft motion and corresponding fore and aft vibration which can be harmful to the knife drives. Since the motion of the knife blades or cutter bars is strictly linear and in opposite directions along a common reciprocation axis that is transverse to a direction of travel of the harvester, vibrational forces are minimized. 
         [0006]    In accordance with a second aspect, the subject application provides a cutter assembly for an agricultural harvester header including a knife drive, and first and second cutter bars connected to the knife drive in side by side relation. The knife drive includes a crank shaft having a first cylindrical portion and a second cylindrical portion radially offset from the first cylindrical portion. A first eccentric sheave is mounted on the first cylindrical portion and a first eccentric rod extends from the first eccentric sheave. Likewise, a second eccentric sheave is mounted on the second cylindrical portion and a second eccentric rod extends from the second eccentric sheave. The first cutter bar is attached to a distal end of the first eccentric rod and the second cutter bar is attached to a distal end of the second eccentric rod. Rotation of the crank shaft provides linear oscillation of the first and second cutter bars. 
         [0007]    In accordance with a third aspect, the subject application provides a sickle knife drive for an agricultural harvester header. The sickle knife drive includes a housing, a crank shaft having first and second cams rotatably supported by the housing, first and second connecting members, and first and second plungers. The first and second connecting members each have first and second ends. The first end of the first connecting member has a first cam follower for engaging the first cam and the first end of the second connecting member has a second cam follower for engaging the second cam. The first and second plungers each have first and second ends. The first plunger is supported for linear motion at a first end of the housing and the second plunger is supported for linear motion at a second end of the housing opposite the first end. The first plunger is connected at the first end thereof to the second end of the first connecting member and the second end thereof to a first sickle knife assembly. The second plunger is connected at the first end thereof to the second end of the second connecting member and the second end thereof to a second sickle knife assembly. With the sickle knife drive being so constructed, rotation of the crank shaft causes rotation of the first and second cams against the first and second cam followers and linear reciprocating motion of the first and second plungers in opposite directions. 
         [0008]    In accordance with a fourth aspect, the subject application provides a drive mechanism for center knife drive of an agricultural harvester header. The drive mechanism includes a crank shaft having a first end and a second end opposite the first end, a flywheel gear, and first and second eccentric journals having outer cam surfaces. The first eccentric journal is eccentrically arranged with respect to a rotational axis of the crank shaft and proximate the first end of the crank shaft. The second eccentric journal is eccentrically arranged with respect to the rotational axis of the crank shaft and adjacent the first eccentric journal. The flywheel gear is coaxial with the rotational axis of the crank shaft and adjacent the second eccentric journal for operatively engaging a driven input gear. The outer cam surfaces of the first and second eccentric journals furthest from the rotational axis of the crank shaft are angularly offset from each other. 
         [0009]    In accordance with a fifth aspect, the subject application provides a drive mechanism for center knife drive of an agricultural harvester header. The drive mechanism includes a first connecting member and a second connecting member. The first connecting member has a first end adapted for receiving a first eccentric journal carried by a rotatable crank shaft and a second end operably connected to a first plunger. The second connecting member has a first end adapted for receiving a second eccentric journal carried by the rotatable crank shaft and a second end operably connected to a second plunger. The first and second plungers are coaxial and configured to reciprocate in opposite directions when driven by rotation of the crank shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0010]    The foregoing summary, as well as the following detailed description of several aspects of the subject application, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the subject application there are shown in the drawings several aspects, but it should be understood that the subject application is not limited to the precise arrangements and instrumentalities shown. 
           [0011]    In the drawings: 
           [0012]      FIG. 1  is front elevation view of a conventional agricultural harvester including a header; 
           [0013]      FIG. 2  is a top plan schematic view of a conventional knife drive applicable to the header of  FIG. 1 ; 
           [0014]      FIG. 3  is a top plan view of a knife drive of a cutter assembly according to an aspect of the subject application in fully extended position; 
           [0015]      FIG. 4  is a top plan view of the knife drive of  FIG. 3  in fully retracted position; 
           [0016]      FIG. 5  is an exploded perspective view of the knife drive of  FIG. 3 ; 
           [0017]      FIG. 6  is a view similar to  FIG. 3  with certain elements of the knife drive omitted for clarity of illustration; 
           [0018]      FIG. 7  is another top plan view of a cutter assembly according to an aspect of the subject application in fully extended position; 
           [0019]      FIG. 8  is an enlarged partial view of Detail A of  FIG. 7 ; 
           [0020]      FIG. 9  is an enlarged partial view of Detail C of  FIG. 8 ; and 
           [0021]      FIG. 10  is an enlarged partial view of Detail B of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Reference will now be made in detail to the various aspects of the subject application illustrated in the accompanying drawings. Wherever possible, the same or like reference numbers will be used throughout the drawings to refer to the same or like features. It should be noted that the drawings are in simplified form and are not drawn to precise scale. In reference to the disclosure herein, for purposes of convenience and clarity only, directional terms such as top, bottom, left, right, above, below and diagonal, are used with respect to the accompanying drawings. Such directional terms used in conjunction with the following description of the drawings should not be construed to limit the scope of the subject application in any manner not explicitly set forth. Additionally, the term “a,” as used in the specification, means “at least one.” The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import. 
         [0023]    Referring now to the drawings, wherein aspects of the subject application are shown,  FIG. 1  illustrates a conventional agricultural harvester  10  such as a combine. Harvester  10  includes a header  12  which is attached to a forward end  14  of the harvester and which is configured to cut crops and to induct the cut crops into a feederhouse  16  as harvester  10  moves forward over a crop field. 
         [0024]    Header  12  includes a floor  18  that is supported in desired proximity to the surface of a crop field and an elongate sickle assembly  20  that extends transversely along a forward edge of the floor  18  i.e., in a widthwise direction of the harvester. Sickle assembly  20  is configured to cut crops in preparation for induction into the feederhouse  16 . Additionally, header  12  includes an elongate, transversely extending harvesting reel  22  disposed above sickle  20 . Harvesting reel  22  is rotatable in a direction suitable for facilitating the induction of cut crops into feederhouse  16 . Header  12  further includes an elongate, rotatable auger  24  which extends in close proximity to a top surface  26  of floor  18 . Auger  24  is configured to cooperate with harvesting reel  22  in conveying cut crops to feederhouse  16 , which is configured to convey the cut crops into harvester  10  for threshing and cleaning. While the foregoing aspect of the subject application is being described with respect to a draper header, the cutter assembly of the subject application can be applied to any other header having use for a knife assembly or sickle section. 
         [0025]    Sickle assembly  20  extends along a forward edge  28  of floor  18 , and generally is bounded by a first side edge  30  and an opposing second side edge  32  of floor  18 . Sickle assembly  20  can be configured to include a first movable knife assembly  34  and a second movable knife assembly  36  (along with an unillustrated stationary knife). The mechanisms of such knife assemblies are known in the art and a typical mechanism is disclosed in U.S. Pat. No. 8,151,547, the entire disclosure of which is incorporated by reference herein. 
         [0026]    Referring to  FIG. 2 , there is schematically depicted a conventional sickle knife drive  38  revealing the path of motion imposed by the knife drive on a pair of oppositely directed movable knives or cutter bars. For simplicity and clarity of illustration, the crank shafts and drive gears of sickle knife drive  38  are omitted. As is known in such knife drives, at least one crank shaft is associated with each movable knife blade or cutter bar. That is, each knife or cutter bar has its own crank shaft where at least two separate crank shafts are required to move the pair of knives. The knife drive  38  includes a housing  40  in which first and second members  42  are supported for pivoting motion at pivot points  44 . A first end of each member  42  is operably driven by an unillustrated crank shaft and a second end of each member  42  is connected to a movable knife  46  (only one of which is shown in  FIG. 2 ). As each member  42  pivots, it swings its respective movable knife  46  through an arcuate path  48 . In so doing, the knives travel not only from side to side (i.e., transverse to the direction of movement of the harvester) but also fore and aft (i.e., in the direction of movement of the harvester). The distance the movable knives travel in the fore and aft direction is indicated by reference “X”. By traveling in the fore and aft direction as well as side to side directions, the movable knives  46  introduce fore and aft vibration into the system. Such vibration not only stresses the knives themselves but also exerts detrimental forces on the moving parts of knife drive assembly, e.g., the crank shafts and gears. As will be appreciated, the fore and aft vibration created by the pivoting knives eventually leads to accelerated failure of the knife drive over time. 
         [0027]    Referring to  FIGS. 3-5 , there are shown several views of a centrally located or “center” knife drive  50  for a cutter assembly of an agricultural header pursuant to an aspect of the subject application. The knife drive includes a housing  52  including first and second opposite ends  54 ,  56  and an opening  58  for receiving a geared input shaft which will be described in greater detail in connection with  FIGS. 8 and 9 . Knife drive  50  also includes a knife blade or cutter bar drive mechanism  59  for moving the cutter bars or knife blades in simple harmonic motion. 
         [0028]    As best shown in  FIG. 5 , the drive mechanism  59  includes a crank shaft  60  having first and second opposite ends  62 ,  64 . The crank shaft  60  further includes first and second journals  66 ,  68  that are eccentric with respect to a crank shaft rotation axis  70  (i.e., an eccentric journal) and angularly offset in the manner described in connection with  FIG. 6 . The first and second journals function as cams as described in detail hereinafter. The first journal can be configured as a cylindrical portion  66  located proximate the first end  62  of the crank shaft  60  and the second journal can be configured as a cylindrical portion  68  located adjacent the first cylindrical portion  66 . Thus, the first and second cylindrical portions are angularly offset from each other such as about 90 to 180 degrees. However, the angular offset can be more or less than 90 to 180 degrees, such as 70, 80, 100, 110, 120, 130, 140, 160, 170, 190 and 200 degrees. Referring to  FIG. 5 , the crank shaft further includes a flywheel  72  located adjacent the second journal  68  and coaxial with the crank shaft rotation axis  70  for operatively engaging a driven input gear, as set forth in  FIGS. 7-9 . The outer cam surfaces of the first and second journal portions  66 ,  68  furthest from the rotational axis  70  of the crankshaft  60  are angularly offset from each other, and preferably angularly offset by about 90 to 180 degrees, but can alternatively be angularly offset more than 180 or less than 90, such as 100-170 degrees or 80-190 degrees. 
         [0029]    Referring to  FIG. 3 , at will be seen that the drive mechanism  59  further includes first and second eccentric sheaves  74 ,  76  respectively mounted on the first and second journals  66 ,  68  with eccentric rods or connecting members  78 ,  80  respectively extending in first and second opposite directions from the first and second eccentric sheaves  74 ,  76 . A first or proximal end  78   a  of the first connecting member is mounted on or otherwise engaged with the first journal  66  and a first or proximal end  80   a  of the second connecting member is mounted on or otherwise engaged with the second journal  68 . The second or distal ends  78   b ,  80   b  of the first and second connecting members  78 ,  80  extend in first and second opposite directions toward the first and second opposite ends  54 ,  56  of housing  52 . That is, first connecting member  78  is engaged with the first journal  66  and extends in a first direction, and second connecting member  80  is engaged with the second journal  68  and extends in a second direction opposite the first direction such that rotation of the crank shaft  70  produces linear reciprocating motion of the ends of the first and second connecting members. As represented in  FIGS. 3-6 , the linear reciprocating motion of the end of the first connecting member  78  is in a direction opposite the linear reciprocating motion of the end of the first connecting member  80 . 
         [0030]      FIGS. 3 and 4  show a pair of plungers  82 ,  84  pivotably connected at first ends  86 ,  88  thereof e.g., via pivots  90 ,  92  to the second ends  78   b ,  80   b  of the eccentric rods or connecting members  78 ,  80 . That is, the first plunger  82  is pivotably connected to the first connecting member  78  and the second plunger  84  is pivotably connected to the second connecting member  80 . Second ends  94 ,  96  of the plungers  82 ,  84  are connected to first and second sickle knife assemblies. More particularly, the second ends of the plungers may be joined such as by clamping or the like to sickle bar coupler members  98 ,  100  which respectively are attached to first and second cutter bars or sickle knife blades  102 ,  104  ( FIGS. 7 and 10 ). As seen in  FIGS. 3-5 , the first and second eccentric rods or first and second connecting members  78 ,  80  can be arcuate or curved in shape in order to more effectively convert rotational motion of crank shaft  60  into linear reciprocating or oscillating motion of the plungers  82 ,  84 . The plungers  82 ,  84  are coaxially arranged with each other and are mounted for linear reciprocal or oscillating motion within the first and second opposite ends  54 ,  56  of housing  52 . To facilitate sliding of plungers  82 ,  84  within the first and second opposite ends of the housing, there may be provided unillustrated bearings or bushings surrounding the plungers as well as seals for keeping oil within the housing. 
         [0031]    Referring to  FIG. 5 , it will be seen that the first ends  78   a ,  80   a  of the first and second eccentric rods or connecting members  78 ,  80  include first clamping portions  78   c ,  80   c  and second clamping portion  78   d ,  80   d . The first claiming portions  78   c ,  80   c  cooperatively engage with second clamping portions  78   d ,  80   d  e.g., via threaded members  78   e ,  80   e  and nuts  78   f ,  80   f  ( FIG. 3 ) in order to form the completed eccentric sheaves  74 ,  76  shown in  FIGS. 3 and 4 . As will be appreciated, the second clamping portions  78   d ,  80   d , are moved from a first non-clamping position when installing the connecting members  78 ,  80  to a second clamping position about journals  66 ,  68  upon completion of installation. That is, the second clamping portions  78   d ,  80   d  are moveable relative to the first clamping portions  78   c ,  80   d  between first and second positions for clamping of respective first and second journals  66 ,  68 . In addition, as shown in  FIG. 5 , in order to promote longer service life of the knife drive  50 , bearings  106  may be mounted within each of the first ends  78   a ,  80   a  of the first and second connecting members or eccentric rods  78 ,  80  between the first clamping portions  78   c ,  80   c  and the second clamping portions  78   d ,  80   d.    
         [0032]    As mentioned above, according to the subject application rotational motion of crank shaft  60  is converted into linear reciprocating or oscillating motion of the plungers  82 ,  84 . This is achieved by the radial and angular offset of the first and second journals  66 ,  68  situated on crank shaft  60  and their cooperation with the first and second eccentric rods  78 ,  80 . Turning to  FIG. 6 , wherein the eccentric rods  78 ,  80  are omitted for clarity of illustration, the angular and radial offset of the first and second cylindrical portions or journals  66 ,  68  can be clearly seen. In particular,  FIG. 6  shows that the first and second journals are radially offset with respect to the crank shaft rotation axis  70  so as to establish first and second cams that cooperatively engage with cam followers defined by the first and second eccentric sheaves  74 ,  76  shown in  FIGS. 3 and 4 . The first and second cams are thus eccentrically arranged with respect to the crank shaft. 
         [0033]    According to an aspect of the subject application, the first and second cams can be matingly received within the cam followers in order to minimize vibration and assure smooth transition of rotational crank shaft motion into linear plunger motion. As noted, the first and second cams are angularly offset from each other about the crank shaft rotation axis. This angular or circumferential offset is indicated by angle “α” in  FIG. 6 . As seen in  FIG. 6 , the coaxially arranged first and second plungers  82 ,  84  define a common reciprocation axis  108  which is perpendicular to and spaced from the crank shaft rotation axis  70  by distance “D”. Angle α ranges from about 90 to 180 degrees. That is, the cam surfaces of the first and second cams (i.e., the first and second eccentric journals  66 ,  68 ) that are furthest from the rotational axis of the crank shaft can be angularly or circumferentially spaced apart by about 90 to 180 degrees, but can be more or less than 90 or 180 degrees, such as 70, 80, 100, 100, 110, 120, 130, 140, 150, 160, 170, 190, and 200 degrees. 
         [0034]    Referring to  FIG. 7 , there is shown a cutter assembly  110  constructed according to an aspect of the subject application. The cutter assembly  110  includes the center knife drive  50  to which is attached a pair of sickle bar coupler members  98 ,  100  which, in turn, are connected to a pair of cutter bars or knife blades  102 ,  104 . An enlarged view of the connection between sickle bar coupler member  100  and cutter bar  104  is shown in  FIG. 10 . Cutter bars  102 ,  104  extend in opposite directions and are arranged in side by side relationship. As will be described below, cutter bars  102 ,  104  are coaxial and move in opposite directions in a linear reciprocating or oscillating path of motion e.g., the linear oscillation of the first and second cutter bars is simple harmonic motion. 
         [0035]      FIG. 8  shows an enlarged view of a portion of knife drive  50 , in particular the drive connection between flywheel  72  and a rotatable input shaft  112  which extends through housing opening  58  ( FIGS. 3-5 ). Input shaft  112  may be driven by an unillustrated hydraulic motor or power take off in the manner known in the art. At its inner end the input shaft  112  carries a gear  114  which engages a corresponding gear  116  on flywheel  72 . Thus, flywheel  72  operably engages the driven gear  114  of input shaft  112  to rotate the crank shaft. As most clearly seen in  FIG. 9 , the gears  114 ,  116  can be cooperating bevel gears. As seen in  FIGS. 7 and 8 , the bevel gear  116  on the face of the flywheel is coaxial with the crank shaft rotational axis  70 . Although depicted as a bevel gear set, it will be understood that other gear arrangements, such as worm or pinion gears, may be suitable for achieving a driving connection between the input shaft  112  and the flywheel  72 . Furthermore, although not illustrated, it is also contemplated that crankshaft  60 , and therefore flywheel  72 , may be directly driven by the output shaft of a drive motor, i.e., without the need for a geared connection. 
         [0036]    Referring back to  FIGS. 3 and 4 , there is shown the operation of the sickle knife drive of the subject application with the plungers  82 ,  84  in the fully extended position ( FIG. 3 ) and fully retracted position ( FIG. 4 ). Plungers  82 ,  84  move between their end positions by virtue of rotation of the crank shaft. As noted above, crank shaft rotation may be achieved by a driving connection between input shaft  112  ( FIG. 8 ) and flywheel  72 . As the crank shaft rotates about axis  70 , the flywheel  72  and the first and second cylindrical members or journals  66 ,  68  are likewise caused to rotate. During such rotation, the outer eccentric cam surfaces of the first and second journals travel inside and exert motive force i.e., cam against the first and second cam follower surfaces defined by the eccentric sheaves  74 ,  76 . This force in turn urges the first ends of the first and second eccentric rods or connecting members  78 ,  80  to orbit in unison around the crank shaft rotation axis  70 . During the course of such orbital motion, the first and second eccentric rods  78 ,  80  are reciprocatively pulled toward one another ( FIG. 4 ) and pushed away from each other ( FIG. 3 ) in equal and opposite directions in a simple harmonic motion fashion. These pulling and pushing forces is transmitted to the plungers  82 ,  84  and ultimately to the cutter bars attached to the knife drive. By being constrained only to linear reciprocating or oscillating motion the plungers transmit such linear motion to the cutter bars such that fore and aft cutter bar motion and corresponding fore and aft vibrations are essentially eliminated. Additionally, by virtue of the second ends of the first and second connecting members moving in equal and opposite directions, lateral vibration is minimized thereby resulting in essentially a vibration-free cutter assembly. 
         [0037]    It will be appreciated by those skilled in the art that changes could be made to the aspects described above without departing from the broad inventive concept thereof. It is to be understood, therefore, that the subject application is not limited to the particular aspects disclosed, but it is intended to cover modifications within the spirit and scope of the subject application as defined by the appended claims.