Abstract:
A system and method for detecting existence of a failed or broken shear bolt supporting all or a portion of a concave of a threshing system of an agricultural combine and utilizing information relating to rates of movement and absence of movement of a concave to determining the existence and non-existence of a failed or broken shear bolt supporting the concave. More particularly, the present system and method is operable to diagnose existence of a broken shear bolt from a rapid downward movement of the concave and non-movement of the concave during operation of a driver for repositioning the concave. Also, existence of a false broken concave condition can be diagnosed by movements of the concave responsive to operation of the driver.

Description:
[0001]     This divisional application claims priority under 35 U.S.C. § 120 from co-pending U.S. patent application Ser. No. 10/978,897 filed on Nov. 1, 2004 by David N Heinsey et al. with the same title, the full disclosure of which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates generally to a system and method for detecting existence of a failed or broken shear bolt supporting all or a portion of a concave of a threshing system of an agricultural combine and, more particularly, to a system and method which utilizes information relating to rates of movement and absence of movement of a concave to determine the existence and nonexistence of a failed or broken shear bolt.  
       BACKGROUND ART  
       [0003]     Commonly, one or more shear bolts are utilized in support of a concave or a section of a concave extending partially around a bottom portion of a rotor of a threshing system of an agricultural combine, which shear bolt or bolts are designed to fail or break to allow the concave or concave section to fall away from the rotor when large slugs of crop material and/or hard foreign objects enter the space between the concave segment and the rotor. This is intended to prevent damage to the threshing system, but also results in degraded performance of the threshing system Typically, if a shear bolt breaks to allow a segment of the concave to fall away from the rotor, contamination in the clean grain and/or discharge of larger pieces of crop material from the crop residue system of the combine will be noticed. Often, the investigation into the decreased performance will begin or will be concentrated on the cleaning system of the combine, such that excessive machine downtime may be required before the failed concave shear bolt is discovered.  
         [0004]     Thus, what is sought is a manner of detecting a failed or broken concave shear bolt automatically and quickly, and which is simple and economical to implement.  
       SUMMARY OF THE INVENTION  
       [0005]     What is disclosed is a system and method for detecting a failed or broken shear bolt supporting a concave of a threshing system of an agricultural combine, which provides one or more of the sought after benefits set forth above.  
         [0006]     According to a preferred aspect of the invention, the threshing system includes a rotatable rotor and at least one concave segment extending around a lower region of the rotor in spaced relation thereto. One longitudinally extending edge of the concave segment is preferable pivotally or hingedly supported to allow movement of the concave segment upwardly and downwardly in relation to the rotor. Such upward and downward movement is preferably accomplished by a driver, which can be, for instance, but is not limited to, a rotary or linear electric motor or actuator, a fluid cylinder, or the like, connected to the concave by a linkage including a shear bolt designed to fail or break when a force is applied against the concave urging it away from the rotor and of a sufficient magnitude to potentially damage the rotor and/or concave. The system also preferably includes a device or sensor such as, but not limited to, a potentiometer or Hall Effect sensor, for sensing or determining a position of the concave relative to the rotor or another suitable location.  
         [0007]     According to a preferred method of operation of the system, the position of the concave is monitored and, if a rate of change of the position in a downward direction exceeds a predetermined value, it is determined that the shear bolt is failed or broken, and a signal representative thereof is outputted. If the concave is at or near its lowest position when the driver is operated to raise the concave, the position thereof will be monitored and, if the position does not change accordingly, it will be determined that the shear bolt is broken.  
         [0008]     Additionally, if the shear bolt is indicated as being broken and the drive is operated and corresponding movement of the concave is determined, the broken shear bolt condition will be determined to be false.  
         [0009]     As a result, both the existence and absence of a failed or broken shear bolt can be determined according to the system and method of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a simplified schematic representation of a rotor and concave of a threshing system of an agricultural combine, showing elements of a system including a representative driver controllably operable f or moving the concave relative to the rotor, and a linkage including an intact shear bolt connecting the driver to the concave, the system being operable for detecting failure or breakage of the shear bolt according to the invention;  
         [0011]      FIG. 2  is another simplified schematic representation of the rotor and concave of  FIG. 1 , showing the shear bolt broken to disconnect the driver from the concave and allow the concave to fall away from the rotor;  
         [0012]      FIG. 3  is a high level flow diagram of steps of the method of operation of the system for detecting failure or breakage of the shear bolt of  FIGS. 1 and 2 ;  
         [0013]      FIG. 4  is another high level flow diagram of steps of the method of operation of the system for detecting failure or breakage of the shear bolt of  FIGS. 1 and 2 ;  
         [0014]      FIG. 5  is still another high level flow diagram of steps of the method of operation of the system for detecting failure or breakage of the shear bolt of  FIGS. 1 and 2 ; and  
         [0015]      FIG. 6  is another high level flow diagram of steps of a method of operation of a system for detecting failure or breakage of the shear bolt of  FIGS. 1 and 2 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Referring now to the drawings, in  FIGS. 1 and 2 , representative threshing apparatus  10  of a threshing system of an agricultural combine is shown. Threshing apparatus  10  includes a cylindrical rotor  12  rotatably driven about a central longitudinal axis  14  therethrough. Threshing apparatus  10  also includes at least one semi-cylindrical shaped concave  16  positioned so as to extend around a lower region of rotor  12  of all or a segment of the length thereof. Here, it should be recognized or understood that concave  16  is intended to be representative of a concave that extends longitudinally along only a portion of the length of rotor  12 , or along the entire length thereof. Concave  16  is shown supported along one longitudinally extending edge thereof, by a pin  18 , for pivotal movement relative to rotor  12 , as generally denoted by arrows A. In this regard, in  FIG. 1 , concave  16  is shown in what would be considered an operative position in spaced relation to an outer cylindrical surface of rotor  12 , for threshing and separating grain introduced with other crop material in the space between rotor  12  and concave  16 . The separated grain would then pass through holes or perforations in the surface of concave  16  so as to subsequently fall or be conveyed into a cleaning system (not shown) of the combine for further processing in the well known manner. The opposite longitudinally extending edge of concave  16  is supported by a linkage assembly  20  including a link arm  22  supported for rotation on a pin  24  connected to a frame or other structural member of the combine for rotation thereabout, as denoted by arrows B, a distal end  26  of link arm  22  being pivotally connected by a bolt  28  to a link  30  which, in turn, is connected by a shear bolt  32 , to concave  16 . Link arm  22  is additionally connected to a driver  34  including a rod  36  extendable upwardly, and retractable downwardly, as denoted by arrows C, for rotating distal end  26  of link arm  22  upwardly and downwardly, as denoted by arrows B, for raising and lowering link  30  and concave  16  as denoted by arrows A.  
         [0017]     Here, it should be noted and understood that driver  34  is representative of a wide variety of drivers and actuators that could be used in connection with concave  16  for raising and lowering it to achieve a desired spacing in relation to rotor  12 , which drivers and actuators can include, but are not limited to, electric rotary and linear motors or actuators, fluid cylinders and the like. It should also be understood that linkage assembly  20  is but an example of a wide variety of different linkage assemblies and arrangements and other apparatus that can be used in connection between a driver, such as driver  34 , and concave  16  for effecting movement of concave  16 .  
         [0018]     Referring more particularly to  FIG. 1 , driver  34  is controllably operable by a control system  38  preferably including a suitable controller  40  such as a conventional processor based controller including a memory  42  and connected by one or more conductive paths  44  to driver  34  and a signal or display device  46 , and also to a position sensor  48  associated with concave  16  for determining a position thereof relative to rotor  12  or another location and outputting information representative thereof to controller  40 . Here, position sensor  48  is in connection with pin  18  so as to be operable for determining a pivotable or rotational position of concave  16  about an axis of rotation of pin  18 , although it should be understood that a wide variety of other sensor devices, such as a proximity sensor or the like, could be used for determining the position of concave  16 . More particularly in this regard, position sensor  48  can be a commercially available and conventionally operable potentiometer or Hall Effect sensor, as just two examples.  
         [0019]     As noted previously, in  FIG. 1 , concave  16  is shown at an operative position in a selected spaced relation to rotor  12 , for separating grain from other crop material introduced into the space by the rotation of rotor  12  in the well known manner. In contrast, in  FIG. 2 , concave  16  is shown dropped or fallen from link  30  of linkage assembly  20  to a non or less operative position, as a result of failure or breakage of shear bolt  32  in such a manner so as to cause disconnection of link  30  from concave  16 . Here, by the term “failure”, what is meant is a shearing or other breakage of shear bolt  32  in such a manner that concave  16  is disconnected or disengaged from link  30 , so as to be capable of freely falling downwardly away from rotor  12  to thereby enlarge the space therebetween. This will typically occur as a result of induction or passage of a large slug or slugs of dense crop material into the space between rotor  12  and concave  16 , or the induction of hard foreign objects into the space, which, at least partially as a result of the rotation of rotor  12 , will apply a radially outwardly directed force against concave  16 , which will be translated thereby and concentrated against the one or more shear bolts  32 , which will have a predetermined load carrying capability. Thus, if the force applied against concave  16  and translated to the one or more shear bolts  32  exceeds the design limit of the shear bolt  32 , the shear bolt will fail or break, thus releasing concave  16  to fall away from rotor  12 , in the well known manner.  
         [0020]     It has been observed that if a shear bolt  32  is broken by application of a force thereagainst exceeding the load limit thereof, the applied force can cause concave  16  to rapidly or abruptly fall away from rotor  12 , so as to result in a rate of change in the position of concave  16  which will be greater than that which will typically occur as a result of normal movements of concave  16  by driver  34 . Information representative of such rapid rate of change will be outputted by position sensor  48  to controller  40 , which can be programmed to compare the sensed rate of change to one or more stored values which can be representative of, for instance, a maximum rate of normal downward movement of concave  16  by driver  34 . As a result, if the sensed rate of positional change exceeds the stored value, controller  40  can be programmed to determine that a broken shear bolt condition exists. Controller  40  can then store information representative of this condition in memory  42  and, if desired, output a warning or alarm signal to a display, such as display  46 , and/or to a warning alarm or the like for alerting the combine operator or other personnel.  
         [0021]     As another aspect of the invention, if concave  16  is at a lower extreme or limit of its travel relative to rotor  12  and breakage of shear bolt  32  occurs, the rapid falling of concave  16  may not occur. However, subsequently, when driver  34  is operated for raising concave  16 , if no corresponding raising or change in position of concave  16  is sensed by position sensor  48 , for instance, for a specified period of time, controller  40  can be programmed to determine that a broken shear bolt condition exists and store information representative thereof and/or output a signal or alarm representative thereof, as desired.  
         [0022]     Still further, if shear bolt  32  has been previously broken and repaired, or erroneously found to have been broken, controller  40  can operate driver  34  to move concave  16  and, if a resultant positional change is detected by position sensor  48 , controller  40  can be programmed to determine that shear bolt  32  is intact or functional, and store information representative of that condition in memory  42  and/or output a signal representative thereof or cancel a signal or alarm indicating a broken shear bolt condition.  
         [0023]     Further in this regard, it should be noted that it is contemplated that controller  40  can include one or more timers or clocks for timing operation of driver  34 , and movement and/or non-movement of concave  16 , and that memory  42  can include a variety of registers for holding information representative of the various times and positions of concave  16 . As examples, such timers can include an initialize shear bolt variables timer; an update previous concave position timer; and a concave not moving timer. Such registers in memory  42  can include, for instance, a current concave position register; and a previous concave position register, either or both of which can be written over as desired. A flip-flop or flag register can also be utilized for storing an indication of a broken shear bolt condition.  
         [0024]     Referring also to  FIGS. 3, 4 ,  5  and  6 , steps of a representative method of operation of system  38  for testing for a broken shear bolt and optionally verifying a broken shear bolt using the above referenced times and registers are set forth. In this example, driver  34  is represented by an electric motor. In  FIG. 3 , at block  50 , the test is initiated. At system startup, it is desirable for the initialize shear bolt variables timer to be set to one second. The process for this is initialized at decision block  52  which determines whether the initialize shear bolt variables timer is not equal to zero, and a key voltage is less than a predetermined value, here, 9.0 volts. If both of these conditions are present, controller  40  will proceed to set the initialized shear bolt variables timer equal to one second, as denoted at decision block  54  and block  56 . After the initialize shear bolt variables timer has been set equal to one second, or the key voltage is not less than 9.0 volts, controller  40  will proceed to decrement the initialize shear bolt variables timer by a value of one (equal to 10 milliseconds), as denoted by block  58 . Then, the controller will set the previous concave position register equal to the current concave position; set the concave not moving timer equal to 5 seconds as denoted at block  62 ; and set the update previous concave position timer equal to one second as denoted at block  64 .  
         [0025]     Controller  40  will then proceed as denoted at A to end test block  66 , then return to block  50  and follow this same sequence of steps as long as the initialize shear bolt variables timer is not equal to zero and/or the key voltage is less than 9 volts. Controller  40  can cycle through this series of steps, including steps  54 ,  56  and  58 , wherein the initialize shear bolt variables timer will be decremented and reset, as long as the key voltage is less than 9 volts. If the key voltage rises to 9 volts or greater, at block  54 , controller  40  will bypass block  56  and proceed to decrement the initialize shear bolt variables timer, reset the previous concave position to the current concave position, set the concave not moving timer to 5 seconds, and set the update previous concave position timer equal to one second, as set forth in blocks  58 ,  60 ,  62  and  64 , then cycle through blocks  66  and  50  and  52 , until the initialize shear bolt variables timer has been decremented to zero and the key voltage has remained at 9 volts or above.  
         [0026]     At block  52 , once the initialize shear bolt variables timer is equal to zero, and the key voltage is still 9 volts or above, controller  40  will proceed from block  52 , as denoted at C, to decision block  68  in FIG.  4 , wherein controller  40  will determine whether a concave shear bolt broken flag is equal to one, denoting a broken condition. If, at block  68 , it is determined that the flag is not equal to one, controller  40  will proceed as denoted at D, to block  70  in  FIG. 5  wherein it will set the concave shear bolt failure alarm equal to an alarm off condition. Controller  40  will then proceed to decision block  72  to determine whether the previous concave position is less than the current concave position. Here, it should be noted that a lesser position value will denote a concave position closer to the rotor, whereas a greater concave position will denote a position farther from the rotor. If, for instance, referring to  FIGS. 1 and 2 , driver  34  has not been operated to move the concave, and controller  40  has most recently executed sequence of steps  58 - 64 , the previous concave position will have been set equal to the current concave position. As a result, at step  72 , the previous concave position should still equal the current concave position. If, on the other hand, driver  34  has been actuated for moving the concave up or down, the previous and current positions should differ accordingly. Also, at the run speed of controller  40 , and the operating speed of driver  34  for moving the concave, any change in concave position equal to or greater than 5 millimeters between sequential executions of step  72 , can be presumed to be indicative of an abrupt shear bolt failure and resultant fall of the concave.  
         [0027]     Thus, at decision block  72 , if the previous concave position is less than the current concave position, controller  40  will proceed to decision block  74  and determine whether the current concave position minus the previous concave position is greater than or equal to 5 millimeters. If not, any difference will be considered normal and controller  40  will proceed on to the next step. However, if there has been a large change in concave position, controller  40  will proceed to set the concave shear bolt broken flag equal to one which is representative of a broken shear bolt condition, as denoted at block  76 . Here, it should be noted that the 5 millimeter value is intended to be a representative value only, and is not intended to limit the present invention.  
         [0028]     Controller  40  will then proceed to calculate a concave motor current, as denoted at block  78 , in preparation for testing whether the concave moves when driver  34  is operated to raise the concave. At decision block  80 , controller  40  determines the presence of necessary conditions for this test, including whether the concave motor (driver  34 ) is energized to raise the concave, a concave bridge output is not an error, concave motor current is less than 5 amps, and the current concave position is equal to the previous concave position. If these conditions are not present, controller  40  will set the concave not moving timer to an initial value, here, 5 seconds, as denoted at block  82 . Subsequently, controller  40  will determine whether the concave not moving timer is equal to zero, at decision block  84 . If controller  40  has proceeded through steps  80  and  82 , the concave not moving timer will be set at 5 seconds, such that at decision block  84 , it will be determined that the concave not moving timer is not equal to zero, and controller  40  will proceed to the steps contained in  FIG. 6 . On the other hand, if all of the conditions of decision step  80  are present, controller  40  will decrement the concave position not changing timer by one (10 milliseconds), as denoted at block  86 . Then, controller  40  will proceed to determine whether the concave not moving timer is equal to zero, and if yes, will proceed to set the concave shear bolt broken flag to one, representing a broken shear bolt condition, as denoted at block  88  then proceed as denoted at B to execute the steps of  FIG. 6 .  
         [0029]     Here, essentially, if the current concave position equals the previous concave position for 5 seconds of operation of driver  34  for raising the concave, controller  40  is determining that a broken shear bolt condition exists. This is a useful test to be conducted when the concave may have been at its lowest position at the time of shear bolt breakage.  
         [0030]     Referring also to  FIG. 6 , after execution of the step of block  84  or the step of block  88 , controller  40  will proceed to decision block  72  to determine whether the update previous concave position timer is equal to zero, at decision block  93 . If no, it will proceed to decrement the update previous concave position timer by one ( 10  milliseconds), as denoted at block  92  and proceed to the end of the test. If the update previous concave position timer is equal to zero, the controller will set the previous concave position equal to the current concave position, as denoted at block  94 . Then, at block  96 , the update previous concave position timer will be set equal to one second and the test will end, as denoted at block  66 .  
         [0031]     Referring again to  FIGS. 3 and 4 , after initiating the test, as denoted at block  50 ; determining that both conditions of decision block  52  are not present; and having a concave shear bolt broken flag condition equals one (indicating a broken shear bolt condition) controller  40  will proceed through a sequence of steps to determine whether the broken shear bolt flag setting is erroneous. Here, at decision block  98 , controller  40  determines whether the thresher is engaged. If yes, a priority  3  concave shear bolt failure alarm is outputted, as denoted at block  100 . This is a high level alarm condition. If, on the other hand, at block  98  it is determined that the thresher is not engaged and running, a priority  1  concave shear bolt failure alarm will be outputted, as denoted at block  102 . Then, controller  40  will determine whether the concave motor is energized, at decision block  104 . If not, it will proceed, as denoted at B, to the sequence of steps shown in the diagram of  FIG. 6 . If, at block  104 , it is determined that the concave motor is energized, controller  40  will proceed to determine whether the current concave position is not equal to the previous concave position, at decision block  106 . If it is determined that the current and previous concave positions are equal, it will be determined that the broken shear bolt condition is true, and controller  40  will proceed to execute the steps of  FIG. 6 . If, at block  106 , it is determined that the current concave position is not equal to the previous concave position, this is an indication that the concave has moved responsive to operation of driver  34 . Accordingly, controller  40  will proceed to set the concave shear bolt flag to a zero condition, indicating that the shear bolt is intact, as denoted at block  108 . The previous concave position will then be set equal to the current concave position, as denoted at block  110 , and controller  40  will proceed to execute the steps of  FIG. 6 .  
         [0032]     From the proceeding discussion, it should be apparent that control system  38  is operable according to the steps of the present invention, to diagnose a shear bolt failure or breakage condition as a result of an abrupt or rapid downward movement of the concave, as denoted by the sequence of steps  70 ,  72 ,  74  and  76 . Additionally, if the concave is at or adjacent to the bottom of the range of normal positions thereof, a broken shear bolt condition can be diagnosed by the steps  80 ,  82 ,  84  and  86 . Still further, if a broken shear bolt condition flag exists, the existence of a broken shear bolt, or non-existence thereof, can be determined by the steps of  FIG. 4 .  
         [0033]     As a result of the operating steps of the system according to the present invention, a shear bolt failure condition can be accurately and quickly diagnosed and determined using the components used for moving and determining the position of the concave.  
         [0034]     It will be understood that changes in the details, materials, steps, and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.