Patent Publication Number: US-2005137002-A1

Title: Mass flow grain monitor and method

Description:
TECHNICAL FIELD  
      This invention relates to harvesting equipment, and more particularly, to grain monitors used on combine harvesters and the like for continuously monitoring the clean grain throughput of the machine.  
     BACKGROUND AND SUMMARY  
      Grain monitors for combine harvesters are known in the art. It is also known in the art to utilize a load cell as part of such a monitor wherein a Wheatstone bridge or the like is utilized to detect minute deformations of a member of the cell that occur when clean grain from an elevator of the harvester impacts or otherwise exerts a load on the member.  
      In installations that use load cells, the load member&#39;s own weight tends to deform the member to a slight extent, introducing errors into the output data unless the weight (tare) of the member is “zeroed out” during initial calibration of the unit. While such calibration is effective so long as the harvester remains on a level surface, problems arise when the harvest encounters up slopes or downslopes during hillside operations. Some machines have included inclinometers which detect inclination of the harvester and provide appropriate input to computers that process the information to deal with the hillside, but systems of that type can be fairly complex and costly.  
      The present invention provides a simple yet effective way of dealing with the hillside problem. Rather than measuring the force of the grain flow horizontally after it leaves the clean grain elevator as in some conventional systems, the present invention contemplates measuring the force vertically as it moves around the upper end of the elevator and generates a centrifugal force. The load member of the cell is arranged generally horizontally such that its weight is directly opposite to the generally vertical centrifugal force being generated by the grain flow as it changes directions from vertical to horizontal. This weight can be easily zeroed out as tare during calibration. More importantly, with this arrangement the change in tare during hillside operations is much smaller than in conventional arrangements because the change is proportional to the trigonometric cosine of the hillside angle rather than the sine. Prior art devices which essentially measure the flow force horizontally introduce an error that is proportional to the change of the sine of the hillside angle.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic side elevational view of a combine harvester incorporating a mass flow grain monitor in accordance with the principles of the present invention, portions of the exterior of the harvester being broken away to reveal internal details of construction;  
       FIG. 2  is an enlarged, fragmentary top perspective view ofthe clean grain holding tank at the top of the harvester showing in particular the upper end of the clean grain elevator assembly with the cover thereof removed to reveal the grain monitor positioned above the upper end of the clean grain elevator;  
       FIG. 3  is a further enlarged top perspective view of the upper end of the clean grain elevator assembly with the top and near sidewall removed to reveal details of construction;  
       FIG. 4  is a fragmentary side elevational view of the clean grain elevator assembly and associated grain monitor with the top and near sidewall removed;  
       FIG. 5  is an exploded perspective view of various components of the clean grain monitor and its associated mounting structure;  
       FIG. 6A  is a schematic illustration of the clean grain monitor illustrating the manner in which forces act upon the load member during operation when the member is in its nominal, generally horizontal position with the harvester on a level surface;  
       FIG. 6B  is a schematic illustration similar to  FIG. 6A  but showing the application of forces to the load member when the harvester experiences hillside operation with a 15° up slope;  
       FIG. 6C  is a view similar to  FIGS. 6A and 6B  showing the application of forces to the load member when the harvester undergoes hillside operations with a 15° downslope;  
       FIG. 7A  is a schematic illustration of a prior art monitor wherein the load member is more vertically disposed in the nominal position when the harvester is on a level surface, and showing the application of forces to the load member at that time;  
       FIG. 7B  is an illustration of the prior art monitor showing the application of forces to the load member thereof when the harvester experiences hillside operations with a 15° up slope; and  
       FIG. 7C  is a view of the prior art monitor similar to  FIGS. 7   a  and  7   b  but showing the application of forces to the load member when the harvester undergoes a 15° downslope during hillside operations. 
    
    
     DETAILED DESCRIPTION  
      The present invention is susceptible of embodiment in many different forms. While the drawings illustrate and the specification describes certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments.  
      The combine harvester  10  in  FIG. 1  is illustrated without a harvesting header attached to the lower front end of feeder housing  12 . During harvesting operations, however, a header of suitable design is supported at the front end feeder housing  12  and directs harvested materials into the same for subsequent processing by internal threshing and cleaning mechanism of the harvester. Generally speaking, waste products such as straw, stalks, leaves, husks, hulls and chaff exit the machine through the rear thereof while clean grain is directed to a clean grain elevator assembly  14  near the bottom of the machine and elevated toward the top of the machine for subsequent deposit and collection within a clean grain tank  16 . At the upper end of the elevator assembly  14 , the grain is transferred to a “bubble up” conveyor  18  having an internal auger  20  that delivers the grain upwardly and inwardly toward the center of tank  16 . A mass flow grain monitor broadly denoted by the numeral  22  is situated adjacent the upper end of clean grain elevator assembly  14 .  
      Referring to  FIGS. 2-5 , elevator assembly  14  includes an elevator  24  having an endless conveyor chain element  26  looped around a pair of rotatable guide components at its upper and lower ends in the form of chain sprockets, only the upper sprocket  28  being illustrated in the figures. Conveyor chain  26  includes an upwardly moving run  30  on one side of sprocket  28  and a downwardly moving run  32  on the other side thereof. A generally vertically extending partition  34  is located between runs  30 ,  32  to help isolate the two areas.  
      Conveyor chain  26  has a plurality of lift paddles  36  affixed thereto at spaced locations therealong for carrying successive collections of clean grain upwardly into the tank  16  from the bottom of the machine when elevator  24  is operating. Conveyor  24  operates at a relatively high rate of speed so that the collections of grain are moved rapidly up out of the lower region of the machine toward the tank  16 .  
      Elevator assembly  14  also includes various walls and housing structure enclosing elevator  24  including, for example, a housing  38  at the upper end of elevator  24  within tank  16 . Among other structure, as shown in  FIG. 4 , housing  38  includes a rear wall  40 , a front wall  42 , and a pair of opposite sidewalls  44  and  46  ( FIG. 2 ). A top cover is also provided, although such cover is removed and not visible in the various figures. Internal panels  48  within housing  38  divide the interior of housing  38  into a pair of compartments  50  and  52 , the rear compartment  50  being utilized to house the upper end of elevator  24  and the front compartment  52  being utilized to direct grain from elevator  24  down through an opening  54  to the bubble up auger conveyor  18 . The shaft  56  of conveyor  18  is illustrated in cross section in  FIG. 4  below opening  54 .  
      Within compartment  50  is disposed an interior guide wall  58  comprising a further part of conveyor assembly  14 . Guide wall  58  is spaced laterally from the upwardly moving run  30  of conveyor chain  26  and includes a lower straight portion  58   a  and an upper curved portion  58   b  that curves around sprocket  28  in generally concentric relationship with the axis of rotation thereof defined by shaft  60 . A longitudinal axis  62  of elevator  24  intersects the axes of rotation of the sprockets at the upper and lower ends of elevator  24 . Curved portion  58   b  of guide wall  58  commences approximately at the point where the upwardly moving run  30  of chain  26  begins to wrap around sprocket  28  and terminates approximately 90° later just short of the axis  62 .  
      Because of the rapid speed of conveyor chain  26 , the clean grain being elevated by elevator  24  essentially produces a flow of crop materials that is moving in a generally vertical, straight line path of travel as it moves upwardly through compartment  50  until reaching the sprocket  28 . As conveyor chain  26  moves around sprocket  28 , the crop materials are flung to the outside of the paddles  36  and engage curved wall portion  58   b , which changes their direction and sends them across the longitudinal axis  62  of the elevator and into chamber  52 , where they engage front wall  42  and fall down through opening  54  into the awaiting bubble up conveyor  18 . Such change in direction of the material flow by curved wall portion  58   b  creates a centrifugal force that bears against curved portion  58   b  as the materials move along the full length thereof. Such centrifugal force is advantageously used by the mass flow grain monitor  22  to provide a continuous measurement of the grain flowing through elevator assembly  14 .  
      Monitor  22 , in a preferred embodiment, includes a load cell broadly denoted by the numeral  64  which includes a member  65  that undergoes minute deformation when subjected to a load. In the illustrated embodiment, load member  65  includes a beam or bar  66  received by a “can”  68  that detects deformation of bar  66  under applied loading. Can  68  is electrically connected to a box  70  ( FIG. 5 ) containing electronic components that receive a signal from can  68  proportional to the load applied against bar  66  and appropriately process such signal to provide an output that can be used in a variety of ways such as, for example, displaying information to the operator of harvester  10 . Such output may also be used to provide information that can be coordinated with global positioning information to provide yield maps and other useful tools for the operator. By way of example, one load cell that has been found suitable for this purpose is available from Digi-Star LLC of Fort Atkinson, Wis. as part no. 403296.  
      As illustrated particularly in  FIGS. 4 and 5 , an inverted generally L-shaped bracket  72  is secured to the exterior of rear wall  40  of housing  38  adjacent its upper extremity and provides a horizontally disposed shelf  74  for supporting load cell  64 . Bar  66  of member  65  is secured to horizontal shelf  74  by bolts  76  that pass through a spacer block  78  and the rear of bar  66  so as to maintain member  65  in a generally horizontal attitude when harvester  10  is on a level surface. Bolts  76  and shelf  74  support member  65  in a cantilever manner, with the forward end of bar  66  projecting forwardly beyond shelf  74  and into overhanging relationship with compartment  50  of housing  38 . To maintain the horizontal disposition of member  65 , the lower cylindrical periphery of can  68  is received within a clearance notch  80  in the leading edge of shelf  74 . An inverted generally U-shaped shield  82  protectively overlies the rear end of load bar  66  and spacer block  78  and is secured to shelf  74  using the same bolts  76  that fasten load bar  66  to shelf  74 .  
      Member  65  has a crop flow engaging portion in the nature of a target plate  84  that effectively comprises an extension of load bar  66 . Target plate  84  is substantially the same width as lift paddles  36  of elevator  24  such that target plate  84  engages substantially the full width of the crop material flow as it moves around the upper end of elevator  24 . As particularly illustrated in  FIG. 4 , target plate  84  is disposed slightly above and overlaps the terminal end of curved wall portion  58   b  and projects forwardly therefrom in vertically spaced relation to elevator  24 . Target plate  84  is so positioned that the longitudinal axis  62  of elevator  24  intersects plate  84  as illustrated in  FIG. 4 . A relatively short strap  86  is fastened at its forward end by bolts  88  to target plate  84  and at its rear end by bolts  90  to the free end of load bar  66  for the purpose of attaching target plate  84  to load bar  66 .  
      As noted above, target plate  84  effectively serves as an extended part of load bar  66  to receive the load applied thereto by the centrifugal force of the crop material flow as it moves around the upper end of elevator  24 . Target plate  84  is slightly downturned in a fore-and-aft direction so as to maintain approximately the same spacing from conveyor chain  26  as the curved wall portion  58   b . Adjacent its free, forward end, target plate  84  is generally straight and flat in a fore-and-aft sense so as to slightly diverge from conveyor chain  26  in a manner to most effectively direct the crop material flow downwardly and forwardly into receiving compartment  52  above outlet  54 .  
      As illustrated in  FIG. 6A , the centrifugal force of the grain flow exerts a vertically upwardly directed force F G  against the member  65  at target plate  84  as the grain moves around the upper end of the elevator  24 , tending to deform member  65  upwardly. On the other hand, the weight of member  65 , including the combined weight of bar  64  and target plate  84 , exerts a vertically downward force F W  that tends to counteract the grain force F G  and deform member  65  downwardly. Thus, the weight of member  65  produces an erroneous output value for the force of the grain flow unless treated as tare and zeroed out by conventional calibration means associated with the monitor  22 , such calibration means are described herein due to the conventional nature thereof. When member  65  is perfectly horizontal as illustrated in  FIG. 6   a , the amount of force F W  that must be zeroed out to obtain an accurate value for the force of the grain F G  corresponds exactly to the weight F W  because F W  and F G  are in vertically direct opposition to one another.  
       FIG. 6C  illustrates, however, that when the combine harvester encounters a downslope during hillside operations, such as for example a 15° downslope, something less than the full weight F W  of the member  65  counteracts the force of the grain F G . This component of F W  in the direction of force F G  is represented in  FIG. 6   c  by the vector “F Y .” The value for F Y  can be mathematically determined as the trigonometric cosine ofthe angle φ multiplied by force F W . In the illustrated example the value of F Y  thus equals the cosine of 15° times the force F W , or 0.966 F W . Thus, because the system has been calibrated with the harvester on level ground when the full weight of member  65  is treated as tare, the output of the monitor will be slightly erroneous, i.e., it will have a small error amounting to 3.4% of the weight of the member  65  during the duration of the 15° downslope.  
       FIG. 6B  illustrates the small error that is introduced into the output from monitor  22  when the harvester encounters a 15° up slope hillside condition. Here again, something less than the full weight F W  of the member  65  is in direct opposition to the grain force F G . Such portion is represented by the value F Y  in  FIG. 6B  and once again can be determined as the cosine ofthe up slope angle  4  times the weight F W . Thus, in this particular example where the up slope angle 4 is 15°, F Y  equals 0.966 F W . Consequently, an output error of 3.4% of the weight of the member  65  will be introduced, but such error is relatively small compared to prior art arrangements as discussed below.  
       FIG. 7A  illustrates a prior art arrangement using a load cell  100  having a load member  101  provided with a load bar  102  and a crop engaging portion  104 . Member  101  is not generally horizontally disposed. Instead, it is generally vertically oriented although, it actual practice, it is typically set in the nominal position to reside at an incline of approximately  150  off vertical. The force of the grain F G  is normal to the longitudinal axis of member  101 , and the weight of member  101  F W  is directed vertically downward, as always. In this arrangement, only a small portion of the weight of member  101  is in direct opposition to the force of the grain and needs to be zeroed out during initial calibration of the system when the harvester is on a level surface. The value for this component F Y  of the weight is determined by multiplying the trigonometric sine of the angle φ times the weight F W . Thus, where φ equals 15°, F Y  equals 0.26 F W . Consequently, the tare to be zeroed out of the system when the harvester is on level ground is an amount which is equal to 26% of the weight of the member  101 . As long as the harvester remains level after the monitoring system has been calibrated, the output from the monitor system should not be affected by the weight of the load member.  
      However, if the harvester encounters a 15° downslope as illustrated in  FIG. 7C , none of the weight F W  ofthe load member  101  is directly opposed to the force ofthe grain F G . Thus, with the system calibrated to remove 26% of the weight of the load member as tare, an error having a magnitude of 26% of the weight of the load member is introduced into the system for the duration of the 15° downslope.  
      A similar error is introduced if the harvester encounters an up slope hillside condition, such as a 15° up slope as illustrated in  FIG. 7B . Here the angle φ between the weight F W  of the load member  101  and its longitudinal axis is 30°, which means that a larger portion of the weight of the load member should be treated as tare in this condition than in the nominal condition illustrated in  FIG. 7A . More particularly, F Y  in the 15° up slope condition of  FIG. 7B  is equal to the sine of angle φ times the weight F W , i.e., F Y  equals 0.50 F W . The difference between F Y  in  FIG. 7B  and F Y  in  FIG. 7A  is 0.24 F W  such that in the 15° up slope condition of  FIG. 7B , an error of 24% of the weight of the load member is introduced into the output of the monitor system.  
      Consequently, it will be seen that in the prior art system where only a small portion of the weight of the load member is treated as tare when the system is initially calibrated, a significant error in output is introduced when the harvester becomes inclined either downwardly or upwardly during hillside operations. At a hillside angle of 15°, such error is on the order of 24-26% of the weight of the load member.  
      On the other hand, in the present invention where the load member is horizontally disposed and the force of the grain flow is measured vertically, the entire weight of the load member is treated as tare when the system is calibrated. This results in a relatively small error in the output of the monitor system when upsloping or downsloping hillside operations are experienced by the harvester, e.g., on the order of 3.4% ofthe weight ofthe load member where the hillside angle is 15°.  
      The foregoing thus shows that the more nearly horizontal the load member of the load cell is when the harvester is on the level ground and the weight of the load bar is zeroed out as tare, the smaller the error that will be introduced into the output of the monitor system during hillside operations. The present invention thus does not require the load member to be perfectly horizontal, but rather is based upon the discovery that by having the load member generally horizontal and measuring force of the grain flow in a generally vertical attitude, significantly improved results can be obtained. Thus, the term “generally horizontal” within the context of the present invention and the claims which follow, means exactly horizontal and  300  on either side thereof. Similarly, the term “generally vertical” means exactly vertical and 30° on either side thereof.  
      The inventor(s) hereby state(s) his/their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his/their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.