Abstract:
A system and method for controlling a load on an agricultural harvester ( 100 ) comprising a first sensor ( 124, 126, 128, 130 ) to sense a first load, a second sensor ( 132, 134, 136, 138 ) to sense a second load, an electronic control unit ( 200 ) coupled to the first sensor and the second sensor, the electronic control unit ( 200 ) being configured to determine a difference between the first load and the second load, and to either (a) raise a harvesting head ( 102 ) or (b) stop the agricultural harvester ( 100 ), or (c) both, when the difference exceeds a threshold load.

Description:
FIELD 
     The invention relates to agricultural harvesters. More particularly, it relates to load control systems and methods for agricultural harvesters. 
     BACKGROUND 
     Harvesting heads or “headers” are elongate, laterally extending devices. They are suspended from a structure called a feederhouse that extends from the front of agricultural combines. They sever the crop plants and carry the severed crop plants to an open front end of the feederhouse. The feederhouse carries the cut crop material rearward and into the agricultural combine itself. The agricultural combine then threshes the cut crop material, separating the grain from the other plant matter, and saves the grain in a grain reservoir or grain tank on the agricultural combine. 
     Harvesting heads travel at relatively high speeds and very close to the ground. As a result they are prone to collide with the ground. The larger and wider they are, the greater the risk of damage to the harvesting head when collisions occur. 
     What is needed, therefore, is a system for controlling or limiting loads due to these ground collisions. It is an object of this invention to provide such a system. 
     SUMMARY 
     In accordance with a first aspect of the invention, a system for controlling the load on an agricultural harvester is provided, the system comprising a first load sensor disposed to sense a first load applied to the agricultural harvester; a second load sensor disposed to sense a second load applied to the agricultural harvester, an electronic control unit coupled to the first load sensor and the second load sensor, wherein the electronic control unit is configured to (a) read a first load signal from the first load sensor, (b) read a second load signal from the second load sensor, (c) determine whether a difference of the first load and the second load exceeds a threshold load, and (d) if the difference exceeds the threshold load, to either (i) lift a harvesting head, or (ii) stop over-the-ground travel of the agricultural harvester. 
     The agricultural harvester may further comprise a self-propelled agricultural harvesting vehicle and a feederhouse pivotally coupled to the front of the self-propelled agricultural harvesting vehicle at a first pivot and a second pivot. 
     The first load sensor may be disposed adjacent to the first pivot, and the second load sensor may be disposed adjacent to the second pivot. 
     The agricultural harvester may further comprise a frame pivotally coupled to the front of the feederhouse at a third pivot and a fourth pivot, and the frame may be configured to support the harvesting head. 
     The first load sensor may be disposed adjacent to the third pivot and the second load sensor may be disposed adjacent to the fourth pivot. 
     The agricultural harvester may further comprise a first feederhouse lift cylinder and a second feederhouse lift cylinder. The first feederhouse lift cylinder and the second feederhouse lift cylinder may be configured to move a forward end of the feederhouse vertically. A rear end of the first feederhouse lift cylinder may be coupled to the self-propelled agricultural harvesting vehicle at a third pivot. A rear end of the second feederhouse lift cylinder may be coupled to the self-propelled agricultural harvesting vehicle at a fourth pivot. 
     The first load sensor may be disposed adjacent to the third pivot. The second load sensor may be disposed adjacent to the fourth pivot. 
     The first load sensor may be disposed adjacent to a front end of the first feederhouse lift cylinder. The second load sensor may be disposed adjacent to a front end of the second feederhouse lift cylinder. 
     The first load sensor may be disposed to sense a first load applied to the left side of the agricultural harvester, and the second load sensor may be disposed to sense a second load applied to the right side of the agricultural harvester. 
     The first load sensor may be disposed to sense the first load at a first position on the left side of the agricultural harvester. The second load sensor may be disposed to sense the second load at a second position on the right side of the agricultural harvester. The first position and the second position may be disposed directly opposite each other and equidistant from a longitudinally and vertically extending plane that passes through the lateral middle of at least one of (a) the agricultural harvester, (b) a harvesting head, and (c) a feederhouse. 
     In accordance with a second aspect of the invention, of method for controlling a load on an agricultural harvester is provided, the method comprising: a step of automatically and electronically sensing a first load applied to the agricultural harvester; a step of automatically and electronically sensing a second load applied to the agricultural harvester; a step of automatically and electronically determining whether a difference in magnitude between the first load and the second load exceeds a threshold load; and a step of automatically and electronically (a) raising an agricultural harvesting head or (b) stopping over-the-ground movement of the agricultural harvester, when the difference in magnitude between the first load and the second load exceeds the threshold load. 
     The step of automatically and electronically sensing a first load applied to the agricultural harvester may comprise a step of automatically and electronically sensing the first load at a first location disposed on the left side of the agricultural harvester. The step of automatically and electronically sensing a second load applied to the agricultural harvester may comprise a step of automatically and electronically sensing the second load at a second location disposed on the right side of the agricultural harvester. 
     The first location and the second location may be disposed directly opposite to each other and equidistant from a longitudinal and vertically extending plane passing through the lateral middle of at least one of (a) the agricultural harvester, (b) a harvesting head, and (c) a feederhouse. 
     The agricultural harvester may comprise a self-propelled agricultural harvesting vehicle and a feederhouse coupled to and extending forward from the self-propelled agricultural harvesting vehicle. The first load may be measured at a location adjacent to the left side of the feederhouse. The second load may be measured in a location adjacent to the right side of the feederhouse. 
     The first load may be measured at a location adjacent to the left side of the feederhouse at a forward end of the feederhouse. The second load may be measured at a location adjacent to the right side of the feederhouse at a forward end of the feederhouse. 
     The first load may be measured at a location adjacent to the left side of the feederhouse at a rear end of the feederhouse. The second load may be measured at a location adjacent to the right side of the feederhouse at a rear end of the feederhouse. 
     The first load may be measured at a front end of a left side feederhouse lift cylinder. The second load may be measured at a front end of a right side feederhouse lift cylinder. 
     The first load may be measured at a rear end of a left side feederhouse lift cylinder. The second load may be measured at a rear end of a right side feederhouse lift cylinder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of an agricultural harvester in accordance with the present invention. 
         FIG. 2  is a side view of the feederhouse of the agricultural harvester of  FIG. 1 . 
         FIG. 3  is a schematic diagram of a hydraulic and electrical control circuit on the agricultural harvester for controlling loads applied to the feederhouse of  FIGS. 1 and 2 . 
         FIG. 4  is a flowchart of the mode of operation of the control circuit of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     In the discussion below, the terms “front”, “forward”, “in front of”, and variants thereof refer to the forward direction of travel of the vehicle as it travels through the field harvesting crops. This direction of travel is indicated by the letter “V” in  FIG. 1 . 
     In the discussion below, the terms “rear”, “rearward”, “behind”, and variants thereof refer to a direction opposite to the forward direction of travel. 
     In the discussion below, the terms “transverse”, “lateral”, or “side-to-side” refer to a direction that is generally horizontal and perpendicular to the direction of travel “V”. 
     Referring now to  FIGS. 1 and 2 , an agricultural harvester  100  comprises a harvesting head  102  which is mounted on a feederhouse  104  that is supported on the front of a self-propelled agricultural harvesting vehicle  106 . 
     The self-propelled agricultural harvesting vehicle  106  is supported on four wheels  108  that define a ground-engaging arrangement and support the agricultural harvester  100  for travel over the ground while harvesting crops. The wheels  108  are connected to a frame  110  of the self-propelled agricultural harvesting vehicle  106 . The agricultural harvester  100  travels through the field in the direction “V” as it harvests crop. 
     The harvesting head  102  includes an elongate frame  112  that supports a left side endless belt conveyor  114 , a center endless belt conveyor  116 , and a right side endless belt conveyor  118 . The left side endless belt conveyor  114 , the center endless belt conveyor  116 , and the right side endless belt conveyor  118  receive crop plants severed from the ground and carry the crop plants in the directions indicated by the arrows superimposed on the conveyors to an aperture  119  located at the rear central portion of the harvesting head  102 . An elongate reciprocating knife  120  severs the crop plants from their roots. The elongate reciprocating knife  120  extends in a transverse direction across substantially the entire width of the harvesting head  102 . 
     Each of the four wheels  108  of the self-propelled agricultural harvesting vehicle  106  is driven in rotation by a corresponding hydraulic motor  122 . The four wheels  108  support the self-propelled agricultural harvesting vehicle  106  for travel over the ground. 
     Four load sensors  124 ,  126 ,  128 , and  130  are located adjacent to the left side of the feederhouse  104 . Four load sensors  132 ,  134 ,  136 ,  138  are located adjacent to the right side of the feederhouse  104 . 
     The load sensor  124  and the load sensor  132  are disposed at either side of the feederhouse  104  at a left side feederhouse pivot  140 , and at a right side feederhouse pivot  142 . 
     The feederhouse  104  is supported on the front of the self-propelled agricultural harvesting vehicle  106  at the left side feederhouse pivot  140  and the right side feederhouse pivot  142 . These pivots constrain the feederhouse  104  to pivot about a laterally extending horizontal pivot axis that is defined by and is coaxial with both the left side feederhouse pivot  140  and the right side feederhouse pivot  142 . 
     The load sensor  124  is disposed to sense the load applied to the self-propelled agricultural harvesting vehicle  106  by the feederhouse  104  at the left side feederhouse pivot  140 . The load sensor  132  is disposed to sense the load applied to the self-propelled agricultural harvesting vehicle  106  by the feederhouse  104  at the right side feederhouse pivot  142 . 
     The load sensor  126  is disposed at the left side of the feederhouse  104  to sense the load applied to the self-propelled agricultural harvesting vehicle  106  by the rear (cylinder) end of the left side feederhouse lift cylinder  144 . The load sensor  134  is disposed at the right side of the feederhouse  104  to sense the load applied to the self-propelled agricultural harvesting vehicle  106  by the rear (cylinder) end of the right side feederhouse lift cylinder  146 . 
     The rear end of the left side feederhouse lift cylinder  144  is coupled to the self-propelled agricultural harvesting vehicle  106  adjacent to the left side of the feederhouse  104 . The rear end of the right side feederhouse lift cylinder  146  is coupled to the self-propelled agricultural harvesting vehicle  106  adjacent to the right side of the feederhouse  104 . 
     The load sensor  128  and the load sensor  136  are disposed at either side of the feederhouse  104  to sense the load applied to the feederhouse  104  by the front end of the left side feederhouse lift cylinder  144  and the front end of the right side feederhouse lift cylinder  146 , respectively. The load sensor  128  is disposed adjacent to the front end of the left side feederhouse cylinder  144 . The load sensor  136  is disposed adjacent to the front end of the right side feederhouse cylinder  146 . 
     The front end of the left side feederhouse lift cylinder  144  is coupled to a lower portion of the feederhouse  104  (which includes a forward frame  148 ) on the left side of the feederhouse  104 . The front end of the right side feederhouse lift cylinder  146  is coupled to a lower portion of the feederhouse  104  (which includes the forward frame  148 ) on the right side of the feederhouse  104 . 
     The left side feederhouse lift cylinder  144  and the right side feederhouse lift cylinder  146  are coupled between the feederhouse  104  and the self-propelled agricultural harvesting vehicle  106  to raise and lower the front end of the feederhouse  104  by extending and retracting under computer control, thereby raising and lowering the harvesting head  102  with respect to the ground. 
     The feederhouse  104  comprises an open-ended generally rectangular boxlike body  147  having a forward end, and the forward frame  148  coupled to the forward end of the boxlike body  147 . 
     The boxlike body  147  encloses a conveyor (not shown) which conveys cut crop material that passes through the forward frame  148  and is received in the forward end  147  of the boxlike body. The conveyor conveys the cut crop material upward and rearward until it exits the feederhouse  104  adjacent to the left side feederhouse pivot  140 , and the right side feederhouse pivot  142 . 
     The forward frame  148  is generally rectangular and defines the aperture into which the cut crop material is inserted by the center endless belt conveyor  116 . 
     The forward frame  148  is coupled to the forward end of the boxlike body  147  on the left side and the right side of the boxlike body  147  at a left side pivot  150  and a right side pivot  152 , respectively. 
     The left side pivot  150  and the right side pivot  152  constrain the forward frame  148  to pivot with respect to the forward end of the feederhouse  104  about a horizontal and laterally extending pivot axis  154  that is coaxial with and passes through the left side pivot  150  and the right side pivot  152 . 
     The angle of harvesting head  102  with respect to the ground can be adjusted by pivoting the forward frame  148  with respect to the forward end of the boxlike body  147 . The forward frame  148  is configured to support substantially the entire weight of the harvesting head  102  on the forward end of the boxlike body  147 . 
     The load sensor  130  and the load sensor  138  are disposed at either side of the feederhouse  104  at or adjacent to the left side pivot  150  and the right side pivot  152  to sense the load applied by the forward frame  148  to the feederhouse  104  at the left side pivot  150  and the right side pivot  152 , respectively. 
       FIG. 2  is a left side view of the agricultural harvester  100 . The agricultural harvester  100  is symmetric about a common longitudinally extending and vertical plane  151  passing which passes through the lateral center of the feederhouse  104 , the lateral center of the self-propelled agricultural harvesting vehicle  106 , and the lateral center of the harvesting head  102 . 
     Thus, the left side arrangement shown in  FIG. 2  is identical to the right side arrangement, but in mirror image form. Thus, the right side load sensors, the right side hydraulic lift cylinder, and the right side pivots and other structures are identical to the left side load sensors, the left side hydraulic the cylinder and the left side pivots. Thus also, each pair of directly opposing left side and right side load sensors are spaced equidistantly away from, but in opposite directions (i.e. one to the left and one to the right) with respect to, a longitudinally and vertically extending center plane of the agricultural harvester  100 , of the harvesting head  102 , and of the feederhouse  104 . 
     Referring to  FIG. 3 , an electronic control unit (ECU)  200  comprises a microprocessor  202 , a random-access memory circuit (RAM)  204 , a read-only memory circuit (ROM)  206  and a signal conditioning/driver circuit  208 . The microprocessor  202  executes programmed instructions stored in ROM  206 . RAM  204  is provided to permit the microprocessor  202  to store calculated values needed for its proper operation. Signal conditioning/driver circuit  208  is provided to permit the ECU  200  receive signals from various sensors and conditional signals for use by the microprocessor  202 , and to boost the signal provided by the microprocessor  202  to signal levels sufficient to operate the components controlled by the ECU  200 . The ECU  200  is coupled to and receives signals from load sensors  124 ,  126 ,  128 ,  130  disposed at the left side of the feederhouse  104 . The ECU  200  is coupled to and receives signals from load sensors  132 ,  134 ,  136 ,  138  disposed at the right side of the feederhouse  104 . 
     The ECU  200  is coupled to and transmits drive signals to hydraulic pump  212  which is a variable displacement pump. The ECU  200  thereby varies the displacement of the hydraulic pump  212  and therefore the hydraulic fluid output of the hydraulic pump  212 . 
     The ECU  200  is coupled to and transmits drive signals to the four hydraulic motors  122  coupled to each of the four wheels  108 , respectively. The four hydraulic motors  122  are variable displacement motors. The drive signals applied to the four hydraulic motors  122  vary the displacement of the four hydraulic motors  122 . 
     The hydraulic pump  212  and the four hydraulic motors  122  together define a controllable powered driving arrangement and are coupled together in a hydrostatic drive circuit. The ECU  200  is configured to vary the speed of the self-propelled agricultural harvesting vehicle  106  over the ground by varying the displacement of the hydraulic pump  212  and the displacement of the four hydraulic motors  122 . 
     The ECU  200  is also coupled to and transmits drive signals to hydraulic valve  210 . Hydraulic valve  210  is coupled to and receives hydraulic fluid under pressure from hydraulic fluid source  214 . Hydraulic valve  210  is coupled to and releases hydraulic fluid to hydraulic fluid reservoir  216 . Hydraulic valve  210  selectively transmits hydraulic fluid to the extend ports  218  on left side feederhouse lift cylinder  144  and right side feederhouse lift cylinder  146 . Hydraulic valve  210  selectively transmits fluid to retract ports  220  on left side feederhouse lift cylinder  144  and right side feederhouse lift cylinder  146 . 
     The ECU  200  is configured to raise the harvesting head  102  by controlling the hydraulic valve  210  to convey hydraulic fluid under pressure from the hydraulic fluid source  214  to the extend ports  218 , and to return hydraulic fluid from the retract ports  220  to the hydraulic fluid reservoir  216 . 
     The ECU  200  is also configured to lower the harvesting head  102  by controlling hydraulic valve  210  to convey hydraulic fluid from the hydraulic fluid source  214  to the retract ports  220  and to return hydraulic fluid from the extend ports  218  to the hydraulic fluid reservoir  216 . 
       FIG. 4  illustrates the operation of the ECU  200  under control of the instructions stored in ROM  206 . 
     The process starts at step  300  and continues to step  302 . 
     In step  302 , the ECU  200  reads signals provided by the left load sensors  124 ,  126 ,  128 ,  130 . 
     In step  304 , the ECU  200  reads signals provided by the right load sensors  132 ,  134 ,  136 ,  138 . 
     In step  306 , the ECU  200  compares the load signal provided by the left load sensors  124 ,  126 ,  128 ,  130  with the load signal provided by the right load sensors  132 ,  134 ,  136 ,  138 . 
     If the ECU determines that the difference in load indicated by the load sensors  124 ,  126 ,  128 ,  130  as compared to the load indicated by the load sensors  132 ,  134 ,  136 ,  138  is higher than a threshold load value stored in the memory circuits of ECU  200 , then the ECU  200  proceeds to step  308 . In step  308 , the ECU  200  transmits a signal to the hydraulic pump  212  and transmits signals to the four hydraulic motors  122  to vary their displacement such that the self-propelled agricultural harvesting vehicle  106  stops its forward motion. 
     If the ECU  200  determines that the difference in load is less than the threshold, the ECU continues to step  312  and the process terminates. 
     In step  310 , the ECU  200  transmits a signal to hydraulic valve  210  to extend the left side feederhouse lift cylinder  144  and the right side feederhouse lift cylinder  146 . When the left side feederhouse lift cylinder  144  and the right side feederhouse lift cylinder  146  are extended, feederhouse  104  rotates clockwise (as shown in  FIG. 2 ) and lifts the front end of the feederhouse  104  higher above the ground. This, in turn, lifts the forward frame  148 , which in turn lifts the harvesting head  102 . 
     After step  310  is executed, the ECU  200  continues to step  312  and terminates. 
     The process of  FIG. 4  is programmed to repeat frequently at regular intervals as the self-propelled agricultural harvesting vehicle  106  travels through the field harvesting crop. Typically, the process of  FIG. 4  is scheduled to be performed every 5 to 40 milliseconds. 
     In the description above, four load sensors are provided on the left side of the feederhouse  104  and four load sensors are provided on the right side of the feederhouse  104 . 
     In another arrangement, one of the load sensors on the left side and one of the load sensors on the right side are read by the ECU  200  and are used in the process of  FIG. 4 . The load sensor  124  and the load sensor  132  are used in this arrangement. Alternatively the load sensor  126  and the load sensor  134  are used in this arrangement. Alternatively the load sensor  128  and the load sensor  136  are used in this arrangement. Alternatively the load sensor  130  and the load sensor  138  are used in this arrangement. 
     In another arrangement two of the load sensors on the left side and two of the load sensors on the right side are read by the ECU  200  and are used in the process of  FIG. 4 . 
     In another arrangement three of the load sensors on the left side and three of the load sensors on the right side are read by the ECU  200  and are used in the process of  FIG. 4 . 
     The advantage of any of the foregoing arrangements is that the system can quickly detect an asymmetrical load on the harvesting head  102  caused by one side or the other side of the harvesting head  102  contacting the ground. When one side of the harvesting head  102  contacts the ground, this appears as a rapidly growing asymmetric load on one side of the feederhouse  104  versus the other side of the feederhouse  104 . The load can be relatively small, but because it is asymmetric (as determined by taking a difference of the signals on the left side and the signals on the right side) it indicates even slight torsional loads that could twist the harvesting head  102  clockwise or counterclockwise (as shown in  FIG. 1 ) with respect to the self-propelled agricultural harvesting vehicle  106 . It is these torsional or twisting loads that pose a significant problem for the agricultural harvester  100  as opposed to an even load exerted rearward across the entire width of the harvesting head  102 . The torsional or twisting loads caused by any impact with the ground or other solid object can cause immediate and significant damage to the harvesting head  102  or the feederhouse  104 . For this reason, it is important to distinguish between the magnitude of a load, generally, on the feederhouse  104 , and the magnitude of the torsional component of a load on the feederhouse  104 . 
     The arrangement described herein permits the ECU  200  to immediately identify a torsional load before it becomes too great, and to reduce that load, either by stopping the combine harvester, or by lifting the harvesting head  102  when this load is sensed. In either case, if it is contact with the ground that is causing the torsional load on the feederhouse  104  to rise suddenly, the stopping of the combine harvester, and the lifting of the harvesting head  102  will mitigate or prevent any such damage due to torsional loads. 
     In another arrangement, either step  308  (stopping the self-propelled agricultural harvesting vehicle  106 ) or step  310  (raising the harvesting head  102 ) can be performed. Both steps need not be performed in order to provide the benefits of reducing damage to the feederhouse  104 . 
     The description and figures herein are provided to illustrate at least one concrete example of how the invention can be practiced. The invention itself, however, is not limited to being practiced in the particular way always described herein. The claims (below) define the invention and encompass more than the specific examples provided herein. 
     For example, the description above of the schematic diagram attached hereto describes an ECU  200 . The ECU  200  may be a single ECU  200 , or it may be two or more ECUs  200  connected over a communications network. A single ECU  200  may perform all of the functions described herein, or a plurality of ECUs  200  may each selectively perform a portion of the functions described herein.