Abstract:
An agricultural harvesting system including a chassis, an agricultural product moving device coupled to the chassis, an airflow system, a cleaning system and an airflow characterizing system. The cleaning system is configured to receive the agricultural product from the moving device. The cleaning system is configured to receive an airflow from the airflow system. The airflow characterizing system is at least partially positioned in the airflow, and is configured to measure an airflow profile across the cleaning system. The airflow characterizing system includes a plurality of sensors that determine airflow by measuring a thermal transfer from the sensors to the airflow. The airflow characterizing system being configured to maintain a substantially constant electrical resistance of the sensors as the airflow varies. The airflow characteristics are measured in the cleaning system and are used to improve the cleaning capacity of the harvesting system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to agricultural harvesters such as combines, and, more particularly, to cleaning systems used in such combines. 
         [0003]    2. Description of the Related Art 
         [0004]    An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning A combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material, such as straw, from the threshing section proceeds through a residue system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle. 
         [0005]    More particularly, a rotary threshing or separating system includes one or more rotors which can extend axially (front to rear) or transversely within the body of the combine, and which are partially or fully surrounded by a perforated concave. The crop material is threshed and separated by the rotation of the rotor within the concave. Coarser non-grain crop material such as stalks and leaves are transported to the rear of the combine and discharged back to the field. The separated grain, together with some finer non-grain crop material such as chaff, dust, straw, and other crop residue are discharged through the concaves and fall onto a grain pan where they are transported to a cleaning system. Alternatively, the grain and finer non-grain crop material may also fall directly onto the cleaning system itself 
         [0006]    A cleaning system further separates the grain from non-grain crop material, and typically includes a fan directing an airflow stream upwardly and rearwardly through vertically arranged sieves which oscillate in a fore and aft manner. The airflow stream lifts and carries the lighter non-grain crop material towards the rear end of the combine for discharge to the field. Clean grain, being heavier, and larger pieces of non-grain crop material, which are not carried away by the airflow stream, fall onto a surface of an upper sieve (also known as a chaffer sieve) where some or all of the clean grain passes through to a lower sieve (also known as a cleaning sieve). Grain and non-grain crop material remaining on the upper and lower sieves are physically separated by the reciprocating action of the sieves as the material moves rearwardly. Any grain and/or non-grain crop material remaining on the top surface of the upper sieve are discharged at the rear of the combine. Grain falling through the lower sieve lands on a bottom pan of the cleaning system, where it is conveyed forwardly toward a clean grain auger. 
         [0007]    In the paper entitled, “Cleaning Shoe Air Velocities in Combine Harvesting of Wheat”, published in the  American Society of Agricultural Engineers  (Volume 29(4): July-August 1986), it is discussed that thermistors were used as sensors heating them well above ambient temperature. And that the resistance change caused by the cooling effect of the air was sensed by measuring the voltage drop across each thermistor. This can be problematic with the sensors being the hottest when the airflow is the lowest, such as when crop material may be lodged against the sensor. 
         [0008]    The cleaning system of prior art harvesters have certain adjustments that can be made, which for the most part are static during the harvesting operation, and there is a lack of information about the airflow in the cleaning system so that adequate airflow adjustments can be made. 
         [0009]    What is needed in the art is an airflow control system that can monitor and adjust the airflow profile in a dynamic fashion as the combine is harvesting crops. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention provides a system and method of measuring and controlling an airflow profile in a cleaning system of a combine as harvesting of a crop is underway. 
         [0011]    The invention in one form is directed to an agricultural harvesting system including a chassis, an agricultural product moving device coupled to the chassis, an airflow system, a cleaning system and an airflow characterizing system. The airflow system includes a fan, and is coupled to the chassis. The cleaning system is coupled to the chassis, and is configured to receive the agricultural product from the moving device. The cleaning system is configured to receive an airflow from the airflow system. The airflow characterizing system is at least partially positioned in the airflow, and is configured to measure an airflow profile across the cleaning system. The airflow characterizing system includes a plurality of sensors that determine airflow by measuring a thermal transfer from the sensors to the airflow. The airflow characterizing system being configured to maintain a substantially constant electrical resistance of the sensors as the airflow varies. 
         [0012]    The invention in another form is directed to an airflow control system used in an agricultural harvesting system. The airflow control system including an airflow generating system and an airflow characterizing system. The airflow generating system includes a fan configured to generate an airflow. The airflow generating system is coupled to the harvester. The airflow characterizing system is at least partially positioned in the airflow. The airflow characterizing system is configured to measure an airflow profile across the cleaning system. The airflow characterizing system includes a plurality of sensors that determine airflow by measuring a thermal transfer from the sensors to the airflow. The airflow characterizing system is configured to maintain a substantially constant electrical resistance of the sensors as the airflow varies. 
         [0013]    The invention in yet another form is directed to a method of controlling airflow in a cleaning system of an agricultural harvesting system. The method includes the steps of generating an airflow in the cleaning system, and characterizing the airflow. The airflow in the cleaning system is characterized with an airflow characterizing system by the execution of the steps of measuring and creating. The measuring step measures portions of the airflow with a plurality of sensors, with each of the sensors producing a signal representative of a thermal transfer from the sensor to the airflow. The airflow characterizing system is configured to maintain a substantially constant electrical resistance of the sensors as the airflow varies. The creating step creates an airflow profile across the cleaning system. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0015]      FIG. 1  is a side view of an embodiment of an agricultural harvester in the form of a combine which includes an embodiment of an airflow control system of the present invention; 
           [0016]      FIG. 2  is a cutaway perspective view of part of the cleaning system contained in the combine of  FIG. 1 ; 
           [0017]      FIG. 3  is a perspective view of a sensor grid of an airflow characterizing system associate with the cleaning system of  FIG. 2 ; 
           [0018]      FIG. 4  is closer perspective view of one of the sensors of the grid of sensors of  FIGS. 2 and 3 ; 
           [0019]      FIG. 5  is a view of a sieve, associated with the cleaning system of  FIG. 2 , having sensors in the form of another embodiment of a sensor grid of the present invention in the combine of  FIG. 1 ; 
           [0020]      FIG. 6  illustrates a closer front view of one of the sensors in the grid of  FIG. 5 ; 
           [0021]      FIG. 7  is a top view of the sensor of  FIG. 6 ; 
           [0022]      FIG. 8  is a schematical representation of an embodiment of an airflow control system of the present invention using elements of  FIGS. 2-7  in the harvester of  FIG. 1 ; and 
           [0023]      FIG. 9  is a schematical side view of the sieve of  FIG. 5  illustrating an airflow past a sensor of  FIGS. 5-7 . 
       
    
    
       [0024]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    The terms “grain”, “straw” and “tailings” are used principally throughout this specification for convenience but it is to be understood that these terms are not intended to be limiting. Thus “grain” refers to that part of the crop material which is threshed and separated from the discardable part of the crop material, which is referred to as non-grain crop material, MOG or straw. Incompletely threshed crop material is referred to as “tailings”. Also the terms “forward”, “rearward”, “left” and “right”, when used in connection with the agricultural harvester and/or components thereof are usually determined with reference to the direction of forward operative travel of the harvester, but again, they should not be construed as limiting. The terms “longitudinal” and “transverse” are determined with reference to the fore-and-aft direction of the agricultural harvester and are equally not to be construed as limiting. 
         [0026]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown an agricultural harvester in the form of a combine  10 , which generally includes a chassis  12 , ground engaging wheels  14  and  16 , a header  18 , a feeder housing  20 , an operator cab  22 , a threshing and separating system  24 , a cleaning system  26 , a grain tank  28 , and an unloading auger  30 . 
         [0027]    Front wheels  14  are larger flotation type wheels, and rear wheels  16  are smaller steerable wheels. Motive force is selectively applied to front wheels  14  through a power plant in the form of a diesel engine  32  and a transmission (not shown). Although combine  10  is shown as including wheels, is also to be understood that combine  10  may include tracks, such as full tracks or half tracks. 
         [0028]    Header  18  is mounted to the front of combine  10  and includes a cutter bar  34  for severing crops from a field during forward motion of combine  10 . A rotatable reel  36  feeds the crop into header  18 , and a double auger  38  feeds the severed crop laterally inwardly from each side toward feeder housing  20 . Feeder housing  20  conveys the cut crop to threshing and separating system  24 , and is selectively vertically movable using appropriate actuators, such as hydraulic cylinders (not shown). 
         [0029]    Threshing and separating system  24  is of the axial-flow type, and generally includes a rotor  40  at least partially enclosed by and rotatable within a corresponding perforated concave  42 . The cut crops are threshed and separated by the rotation of rotor  40  within concave  42 , and larger elements, such as stalks, leaves and the like are discharged from the rear of combine  10 . Smaller elements of crop material including grain and non-grain crop material, including particles lighter than grain, such as chaff, dust and straw, are discharged through perforations of concave  42 . 
         [0030]    Grain which has been separated by the threshing and separating assembly  24  falls onto a grain pan  44  and is conveyed toward cleaning system  26 . Cleaning system  26  may include an optional pre-cleaning sieve  46 , an upper sieve  48  (also known as a chaffer sieve), a lower sieve  50  (also known as a cleaning sieve), and a cleaning fan  52 . Grain on sieves  46 ,  48  and  50  is subjected to a cleaning action by fan  52  which provides an airflow through the sieves to remove chaff and other impurities such as dust from the grain by making this material airborne for discharge from straw hood  54  of combine  10 . Grain pan  44  and pre-cleaning sieve  46  oscillate in a fore-to-aft manner to transport the grain and finer non-grain crop material to the upper surface of upper sieve  48 . Upper sieve  48  and lower sieve  50  are vertically arranged relative to each other, and likewise oscillate in a fore-to-aft manner to spread the grain across sieves  48 ,  50 , while permitting the passage of cleaned grain by gravity through the openings of sieves  48 ,  50 . 
         [0031]    Clean grain falls to a clean grain auger  56  positioned crosswise below and in front of lower sieve  50 . Clean grain auger  56  receives clean grain from each sieve  48 ,  50  and from bottom pan  58  of cleaning system  26 . Clean grain auger  56  conveys the clean grain laterally to a generally vertically arranged grain elevator  60  for transport to grain tank  28 . Tailings from cleaning system  26  fall to a tailings auger trough  62 . The tailings are transported via tailings auger  64  and return auger  66  to the upstream end of cleaning system  26  for repeated cleaning action. A pair of grain tank augers  68  at the bottom of grain tank  28  convey the clean grain laterally within grain tank  28  to unloading auger  30  for discharge from combine  10 . 
         [0032]    The non-grain crop material proceeds through a residue handling system  70 . Residue handling system  70  may include a chopper, counter knives, a windrow door and a residue spreader. 
         [0033]    Now, additionally referring to  FIGS. 2-9  there is shown an airflow characterizing system  72  (illustrated schematically in  FIG. 8 ) having a controller  74 , airflow alteration devices  76 , a temperature sensor  78  and a sensor grid  80  or  80 ′. Two embodiments of the present invention are illustrated, one being shown in  FIGS. 2-4  and another in  FIGS. 5-7 . 
         [0034]    Controller  74 , while shown as a standalone controller, will likely have its functions incorporated into a controller that performs other functions in combine  10 . Temperature sensor  78  is used to measure the temperature of an airflow  84  or  84 ′ and that temperature is used by controller  74  to determine the heat dissipation of sensors  82 ,  82 ′ that make up sensor grid  80 ,  80 ′, to thereby arrive at an airflow detected by each sensor  82 ,  82 ′ and the measured airflow profile. 
         [0035]    Sensor grid  80  is illustrated in  FIGS. 2 and 3  where sensor grid  80  is positioned in an airflow  84 . Airflow  84  originates by the action of fan  52  and it is used in cleaning system  26  to clean the grain. Sensor grid  80  is a grid of sensors  82  that are generally arranged in a plane that is substantially normal to the direction of airflow  84 . Although the positioning of sensors  82  is illustrated as being generally ordered in regularly spaced intervals, other positions within the grid are also contemplated. Airflow  84  is detected by sensors  82  and this information is provided to controller  74  so that the measured airflow profile across cleaning system  26  is established, so that the airflow profile can be altered by airflow alteration device  76 . Airflow alteration device  76  can also be understood to be an airflow adjusting system  76  that can consist of a variety of passive and active device that can alter characteristics of airflow  84  as it passes through cleaning system  26 . 
         [0036]    Sensor grid  80 ′ is illustrated in  FIG. 5  where sensor grid  80 ′ is positioned in an airflow  84 ′, which is generally perpendicular to sieve  46 ,  48 ,  50 . Airflow  84 ′ is schematically shown at an angle in  FIG. 5  to show that the airflow as it goes through sieve  46 ,  48 ,  50  is angled upwardly. Airflow  84 ′ originates by the action of fan  52  and it is used in cleaning system  26  to clean the grain. Sensor grid  80 ′ is a grid of sensors  82 ′ that are generally arranged in a plane that is substantially normal to the direction of airflow  84 ′. Sensors  82 ′ are coupled to fins of sieve  46 ,  48  or  50 , as shown in more detail in  FIG. 6 . A sensor  82 ′ is depicted in  FIG. 7 , with a thermistor in distal end  86 ′. The thermistor is positioned, so that the heat conduction in the assembly and to the surrounding air is known, and generally, even substantially, consistent between sensors  82 ,  82 ′ in respective grids  80 ,  80 ′. Although the positioning of sensors  82 ′ is illustrated as being generally ordered in regularly spaced intervals, other positions within the grid are also contemplated. Airflow  84 ′ is detected by sensors  82 ′ and this information is provided to controller  74 , in the form of a signal that is related to heat transfer to the surrounding air, so that an airflow profile across cleaning system  26  is established, allowing controller  74  to alter the airflow, and hence the airflow profile, by way of airflow alteration device  76 , which can also be understood to be an airflow adjusting system  76  that can consist of a variety of passive and active device that can alter characteristics of airflow  84 ′ as it passes through cleaning system  26 . 
         [0037]    While the present invention could use both a grid  80  and a grid  80 ′ on one or more of sieves  46 ,  48  or  50 , for the ease of discussion, it will be assumed that just one grid  80  or  80 ′ will be used in a combine  10 . The measured airflow profile can be understood to provide a distribution of airflows that controller  74  seeks to optimize, as compared to a selected airflow profile that is selected based on grain and material other than grain (MOG) characteristics. 
         [0038]    The operational parameters of the combine harvester cleaning system  26  are dependent on the characteristics of the air flowing in cleaning system  26 . The present invention uses multiple sensors  82  or  82 ′ respectively arranged in sensor grids  80 ,  80 ′ to measure characteristics of air passing through cleaning system  26  and more particularly sieve  46 ,  48  and  50  for the purpose of defining the operational efficiency of cleaning system  26 . Airflow characterizing system  72  provides meaningful data that can be considered to be an airflow profile output under the circumstances associated with collecting data while combine  10  is operational. The meaningful data is used by controller  74  to control various settings within combine  10 . 
         [0039]    During harvesting operations, and airflow system  52 ′ that includes fan  52  is used to generate a volume of high velocity air which is strategically blown through cleaning system sieves  46 ,  48 ,  50  to provide an air blast for pneumatic separation of grain from MOG. The purpose of the air blast is to assist the mechanical separation of grain and MOG. Sieves  46 ,  48  and  50  are physically very large assemblies positioned within combine  10 . During operation, sieves  46 ,  48 ,  50  reciprocate back and forth at a frequency of about 4.5 Hz (with some combines operating at frequencies between 3.3 and 5.8 Hz). Due to the motion and location of sieves  46 ,  48  and  50 , as well as taking into account the dirty conditions and volume of crop passing over the sieves, there is no system in the prior art to measure the characteristics of the air flowing through sieves  46 ,  48 ,  50 . The present invention has the ability to identify the overall airflow characteristics for the entire area of a sieve, thereby allowing the settings of combine  10  to be continually optimized. In the prior art, without knowing the airflow characteristics in the cleaning system, the settings of the combine are not able to be adjusted to optimize the cleaning system performance. The optimum settings for a given crop condition are difficult to determine without knowing the airflow characteristics. 
         [0040]    Generally, in the prior art, the settings are held constant even as crop conditions change, causing the cleaning system to never be optimized and even if the settings were good for one crop condition, with changes to the crop condition causing the cleaning system performance to decrease. The settings are held constant because optimizing the settings without knowing the airflow characteristics is not practical. 
         [0041]    In the present invention a series of sensors  82 ,  82 ′, such as in the form of thermistors, are placed in cleaning system  26  to quantify the spatial air velocity in cleaning system  26 . The type of sensors might include, but are not limited to, thermistors, and could among other types include: hot wire anemometers, vane anemometers, pitot tube pressure transducers, etc. For purposes of discussion the preferred embodiment will be considered to be thermistors, with the thermistors being located at a distal end  86 ,  86 ′ of sensors  82 ,  82 ′. The locations that sensors  82 ,  82 ′ could be positioned within combine  10  include, but are not limited to, the inlet or outlet of cleaning fan  52  or other fans, between the sieve louvers, on the chaffer, or shoe sieve, between the chaffer and shoe sieve, below the shoe sieve or above the chaffer sieve. 
         [0042]    The signal from sensors  82 ,  82 ′ (thermistors) is used to quantify the local air velocity, at the sensor&#39;s location. The optimum air pattern in cleaning system  26  for a given crop and condition is established, prior to harvesting, either by an empirical, analytical or stochastic model or some combination thereof to identify what the optimum air pattern in cleaning system  26  should be. A significant aspect of the present invention is the ability use sensors  82 ,  82 ′ so that they can accurately depict the characteristics of the airflow being measured in combine  10  during operation. Airflow characterizing system  72  is used while crop is being processed by cleaning system  26  to identify and to adjust for the optimum air distribution in cleaning system  26 . Additionally, airflow characterizing system  72  can be used while the cleaning system is not processing crops to provide design engineers with information regarding the airflow distribution in the system. The airflow distribution is used to identify design changes to cleaning system  26  and to identify the optimum no-crop-load air distribution. 
         [0043]    The use of thermistors by the present invention, relative to both crop airflow and non-crop airflow measurements, is the technique used to quantify the air velocity with the thermistors. There are at least two ways in which a thermistor is used to quantify air velocity by the present invention. First, the thermistor is electrically placed in series with a precision resistor and the circuit is subject to a constant excitation, with the variation in current through the resistor and thermistor being monitored, which is representative of heat transfer to the airflow and hence of the velocity of the airflow past the sensor. With a known air temperature, the heat transfer from the thermistor is mathematically related to the airflow past sensor  82 ,  82 ′. The second approach uses a feedback control loop to maintain a constant resistance in the thermistor, with the control loop characteristics then providing a signal that is related to the heat transfer of the thermistor and thus the airflow past the thermistor. 
         [0044]    Both techniques require the relationship between the heat transfer from the thermistor to the air to be quantified, as this relationship allows the air velocity to be indirectly measured. For purposes of the present invention, the second technique is considered the preferred method. The first technique results in the sensor being hottest when the air velocity past the thermistor is at a minimum. This could occur if there was a buildup of MOG on the thermistor. Having dry MOG against a thermistor, which could reach temperatures in excess of 100° C., could be undesirable, at least resulting in sensor failure. The advantage of the preferred second system, with the constant resistance thermistor, is that the thermistor temperature is held constant, regardless of the air velocity past the thermistor, thereby mitigating overheating risk. This particular system maintains a nearly constant resistive value for the sensor  82 ,  82 ′, hence keeping the thermistor at a generally constant temperature. Controller  74  alters the current flow through the thermistor (or the voltage across the thermistor) to maintain the thermistor resistance value. The controlled current flow is the signal that relates to the heat transfer to the air from the thermistor, and hence is representative of the airflow past the thermistor. 
         [0045]    The airflow velocity in cleaning system  26  is affected by the amount, or load of crop in cleaning system  26 . By having sensor grid  80 ,  80 ′ to provide several airflow measurements, the airflow profile across the cleaning system, several forms of adjustment can be made by control system  72  to improve efficiency of cleaning system  26 . To effectively control the airflow profile in cleaning system  26  a number of adjustments can be made by airflow adjusting system  76  to achieve the optimum air pattern, including but not limited to: 1. Divert the air in the system, for example, a series or grid of rotatable louvers, or vanes can be added in front of, or below, sieve  46 ,  48 ,  50 , in the fan ductwork, and or between the upper and lower sieves. The louvers are used to modify the spatial distribution or pattern of airflow in cleaning system  26  as well as the average air velocity. 2. Change the speed of the cleaning fan. 3. Varying the opening size of the inlet and or outlet of cleaning fan  52 . 4. The sieve slat openings could be adjusted (opened more or opened less). 5. Additional fans can be added to cleaning system  52 , which are turned off/on/sped up/slowed down. 6. The oscillation frequency of cleaning system  26  can also be adjusted. 7. The sieve motion (stroke length, angle of inclination, angle of oscillation) can be modified. 8. Air exhaust ports can be open/closed. 9. The ground speed of combine  10  can be slowed down or sped up. 
         [0046]    The present invention has certain advantages including improved cleaning system performance allowing cleaning system  26  to be able to more effectively separate grain from MOG. Further, the feedback from airflow characterizing system  72  can be used by either the operator to adjust elements of combine  10  and/or it could be used in conjunction with control software to allow combine  10  to make autonomous adjustments of combine  10 . 
         [0047]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.