Abstract:
An apparatus and method for calibrating a PTO for driving a header of an agricultural windrower, wherein a programmable control module in connection with at least signal operated device in operative control of a variable displacement pump operable for controlling operation of the PTO, is programmed as part of an automatic calibration routine for determining values for the control signals required for operating the header at a predetermined target speed for a plurality or range of speeds of an engine driving the pump, such at the pump can be controlled to minimize occurrences of overpumping of fluid and resultant problems.

Description:
[0001]     This application claims the benefit of U.S. Provisional Application No. 60/699,551, filed Jul. 15, 2005. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to agricultural windrowers and, more particularly, to apparatus and a method for calibrating a draper header on a windrower.  
       BACKGROUND OF THE INVENTION  
       [0003]     U.S. Pat. No. 6,901,729, is incorporated herein by reference in its entirety. U.S. Provisional Application No. 60/699,551, filed Jul. 15, 2005, is also incorporated herein by reference in its entirety.  
         [0004]     A windrower typically consists of a self-propelled tractor or similar vehicle, and a cutting mechanism which is either towed by the tractor or carried thereby. The cutting mechanism carried by a windrower is typically referred to as a header, and is supported on the windrower by forwardly projecting arms. Briefly, the arms comprise elements of a lift and flotation mechanism or mechanisms operable for setting a height of the header above the ground or other surface over which the windrower moves, the flotation permitting the header to ride lightly up and over rises in the terrain during field operation.  
         [0005]     Headers are typically available in a variety of configurations. Common elements of different headers include cutters operable for severing crops from the field. One typical cutting mechanism is a sickle cutter which includes a row of knives which extend across the width of the header and which are powered to move reciprocally sidewardly relative to a sidewardly extending array of fixed knives or bars, thereby effecting a cutting action. A typical cutting speed for a sickle type cutter is about 1500 to 1800 strokes per minute. Additional driven elements of a header can include elements for conveying cut crop material, such as a system of draper belts configured and operable for conveying the cut crop material sidewardly toward the center of the header, or side of the header.  
         [0006]     The cutters and draper belts can be commonly powered using a fluid drive, such as a fluid power takeoff (PTO). A pump driven by the engine of the tractor provides pressurized fluid to the PTO system. Fluid conduits, such as hoses, connect the PTO system with fluid motors of the fluid drive. The pump can be of variable displacement, the pressurization and direction of fluid flow, and thus the speed and direction of operation of the cutters and draper belts, being controlled by solenoids. Varying electrical current signals are utilized for operating the solenoids, for operating the header at the desired speed and in the desired direction, and the electrical current required for driving the header at a selected speed would need to be known, such that the controller controlling the solenoids can apply the correct current responsive to an operator command, or when conditions change, such as a change in speed of the engine driving the pump. As an example, if a particular current signal is applied to the solenoids for the engine operating at a given speed, and the engine speed is subsequently increased or decreased, the fluid flow generated by the pump will correspondingly change. If the fluid flow increases, the excess may be diverted to tank via a diverter or pressure relief valve and be subjected to undesirable heating. A tractor, and thus the PTO system, may be configured for use with any of a variety of different headers having different current level requirements for driving the cutters and drapers.  
         [0007]     Therefore, it would be desirable to have an apparatus and method which enables calibrating PTO current values with an operating speed for a given header, and to facilitate the ability to maintain the current at the level required for achieving desired header performance under varying conditions such as varying engine speeds.  
       SUMMARY OF THE DISCLOSURE  
       [0008]     What is disclosed is an apparatus and method which enables calibrating signals for operating a PTO for desired header operation for a given header installed on a windrower, particularly a draper header, to facilitate precise control of the header using the signals, including under changing conditions such as changing engine speeds or the like.  
         [0009]     According to a preferred aspect of the invention the method and apparatus utilizes a programmable control module in connection with at least one signal controlled device operable for controlling operation of the PTO, which signal controlled device is preferably a solenoid controlled pump. The displacement of the pump is variably controllable as a function of the signals, by varying a swash plate angle of the pump. The pump is preferably driven by an engine of the windrower and is thus subject to the effects of varying the engine speed, such as between a low idle speed and a higher operating or harvesting speed. More particularly in this regard, by increasing the engine speed, the pump speed will be increased, and if the swash plate angle is not correspondingly adjusted to decrease the displacement of the pump, the result will be greater pump output. Any pump output in excess of that necessary for operating the header at the prescribed speed will be diverted by a diverter or pressure relief valve to tank. This is undesirable, as it unnecessarily consumes engine power and heats the hydraulic fluid which can result in heat related breakdown and failure of components and fluid.  
         [0010]     To avoid or limit these problems, the control module is programmed as part of an automatic calibration routine for controlling the speed of the engine at a plurality of predetermined engine speeds, respectively; and while the speed of the engine is controlled at each of the predetermined engine speeds:  
         [0011]     outputting an initial control signal to the signal controlled device having a predetermined initial signal value within a predetermined signal range for the engine speed;  
         [0012]     determining an operating speed of the header resulting from the outputted initial control signal;  
         [0013]     comparing the operating speed of the header resulting from the outputted initial control signal to a predetermined target speed value for the header, and:  
         [0014]     if the operating speed of the header resulting from the outputted initial control signal is equal to the target speed value, storing information representative of the initial signal value; and  
         [0015]     if the operating speed of the header resulting from the outputted initial control signal is not equal to the target speed value, then calculating and outputting at least one changed control signal to the signal controlled device having a signal value within the predetermined range and incrementally greater or less than the initial control signal value, for changing the operating speed of the header so as to equal the target speed value, and storing information representative of the signal value of the changed control signal for operating the header at the target speed.  
         [0016]     As a result, a map of control signal values for operating the header at the target speed for a range of engine speeds is developed. Subsequently during operation, the map can be utilized for controlling the header at the target speed, and for calculating control signal values for operating the header at speeds other than the target speed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:  
         [0018]      FIG. 1  is a side elevational view of a crop harvesting machine of the type with which the invention may be used, showing a header including a sickle cutter in connection with apparatus of the instant invention;  
         [0019]      FIG. 2  is a schematic of a PTO driveline of the machine of  FIG. 1 ;  
         [0020]      FIG. 3  is a high level flow diagram of steps of a preferred embodiment of a computer program of the invention;  
         [0021]      FIG. 3   a  is a continuation of the high level flow diagram of  FIG. 3 ;  
         [0022]      FIG. 4  is a written listing of steps of the preferred program of the invention;  
         [0023]      FIG. 5  is a written listing of further steps of the preferred program of the invention;  
         [0024]      FIG. 6  is a written listing of still further steps of the preferred program of the invention;  
         [0025]      FIG. 7  is a written listing of still further steps of the preferred program of the invention; and  
         [0026]      FIG. 8  is a written listing of still further steps of the preferred program of the invention  
         [0027]      FIG. 9  is a written listing of steps of the preferred program of the invention;  
         [0028]      FIG. 10  is a written listing of further steps of the preferred program of the invention;  
         [0029]      FIG. 11  is a written listing of still further steps of the preferred program of the invention;  
         [0030]      FIG. 12  is a written listing of still further steps of the preferred program of the invention; and  
         [0031]      FIG. 13  is a written listing of still further steps of the preferred program of the invention;  
         [0032]      FIG. 14  is a written listing of still further steps of the preferred program of the invention;  
         [0033]      FIG. 15  is a written listing of still further steps of the preferred program of the invention;  
         [0034]      FIG. 16  is a written listing of still further steps of the preferred program of the invention;  
         [0035]      FIG. 17  is a written listing of still further steps of the preferred program of the invention;  
         [0036]      FIG. 18  is a written listing of still further steps of the preferred program of the invention;  
         [0037]      FIG. 19  is a written listing of still further steps of the preferred program of the invention;  
         [0038]      FIG. 20  is a written listing of still further steps of the preferred program of the invention;  
         [0039]      FIG. 21  is a written listing of still further steps of the preferred program of the invention;  
         [0040]      FIG. 22  is a written listing of still further steps of the preferred program of the invention;  
         [0041]      FIG. 23  is a written listing of still further steps of the preferred program of the invention;  
         [0042]      FIG. 24  is a written listing of still further steps of the preferred program of the invention;  
         [0043]      FIG. 25  is a written listing of still further steps of the preferred program of the invention;  
         [0044]      FIG. 26  is a written listing of still further steps of the preferred program of the invention;  
         [0045]      FIG. 27  is a written listing of still further steps of the preferred program of the invention; and  
         [0046]      FIG. 28  is a written listing of still further steps of the preferred program of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0047]     Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art, and they will not therefore be discussed in significant detail. Also, any reference herein to the terms “left” or “right” are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application of any element may already by widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail.  
         [0048]      FIG. 1  shows the present invention utilized in connection with a self-propelled windrower  10 ; however, it will be appreciated that the principles of the present invention are not limited to a self-propelled windrower, or to any specific type of harvesting machine.  
         [0049]     In the illustrated embodiment, the self-propelled windrower  10  comprises a tractor  12  and a header  14 , the header  14  being attached to the front end of a frame  18  or chassis of the tractor  12 . The header may be of generally any suitable construction and design, and will include crop-harvesting mechanisms, such as a sickle cutter  20 . Header  14  additionally includes a reel  24  rotatable at a fixed or variable speed, as denoted by arrow A, for directing crops toward header  14  for harvesting by sickle cutter  20 . A draper  26  comprising endless belts is disposed and operable for directing the harvested crop toward the center of header  14 .  
         [0050]     Sickle cutter  20  of header  14  includes a row of knives extending sidewardly across the lower front of header  14  and reciprocally driven in the sideward direction, by at least one drive  34  which preferably includes a fluid motor  36 . Fluid motor  36  is connected in fluid communication with a PTO  38  of tractor  12 , by fluid lines  40  and  42 , for receiving pressurized fluid therefrom, for powering the reciprocating movement of the sickle knives, in the well known manner. Reel  24  and draper  26  can also be fluid driven, reel  24  by another fluid PTO, and draper  26  also by PTO  38 .  
         [0051]     Header  14  is removably mountable on a pair of lower arms which extend forwardly from frame  18  of tractor  12 , and which are movable upwardly and downwardly for positioning the header at a desired cutting height, or at an elevated transport position, using one or more lift cylinders (not shown), also in the well known manner. The upper end of the header is connected to frame  18  by an upper or center link connected to a mechanism operable for tilting the header to a desired orientation, again, in the well known manner.  
         [0052]     A typical operating speed for sickle  20 , will be about 1800 cycles per minute. Because header will be interchangeable on windrower  10  with other headers, and receive pressurized fluid from and are controlled by PTO  38 , as noted above, it is desirable to have a capability to calibrate the output of PTO  38  with the output of the header for optimizing header performance, and for providing a capability for adjusting to changing conditions, particularly changing engine speed.  
         [0053]     PTO  38  includes a PTO driveline  50  including a fluid valve arrangement  52  controllably operable for directing pressurized fluid through fluid lines  40  and  42  as desired or required for powering a header, such as header  14  or header  16 , connected to windrower  10 .  
         [0054]     Referring also to  FIG. 2 , which is a schematic of PTO driveline  50 , the flow of pressurized fluid to valve arrangement  52  is generated by a variable displacement pump  66 , the displacement of which is determined by the angle of an internal swash plate, the angle being controlled by a header PTO forward/reverse solenoid  54 . In another embodiment, the pump can be a fixed displacement pump operated by a header PTO forward solenoid  56  and a header PTO reverse solenoid  58 . Solenoid  54  is controlled by an electrical signal, the electrical current value of which can be very precisely controllably varied through a range between zero and a greater amount. PTO driveline  50  includes a programmable control module  60  connected to header PTO forward/reverse solenoid  54  by suitable conductive paths  62 , which can be, for instance, wires of a wiring harness. Control module  60  is preferably a conventionally constructed and operable microprocessor based tractor control module, or the like, suitably located on tractor  12 , such as in an operator cab  64 . Pump  66  is driven by an engine  68  of tractor  12 , in the well known manner. Pump  66  is operable for providing fluid pressurized to predetermined system pressure by operation of engine  68  at at least a low idle speed, which is about 900 rpm.  
         [0055]     Other pertinent elements of PTO driveline  50  include a header PTO switch  70  selectably operable by an operator for selecting a forward or reverse direction of operation of the PTO; a header speed switch  72  selectably operable by an operator for increasing or decreasing the speed of operation of the header; a header PTO emergency stop switch  74 ; a seat switch  76 ; and a display device  78 , which can be, for instance, an interactive touch screen device or the like which can be automatically adapted or turned on for receiving operator inputs, each of switches  70 ,  72 ,  74  and  76 , and device  78 , being located in operator cab  64  and connected to the control module  60  via suitable conductive paths  62 . Electrical power is provided in the normal manner from an electrical system of the tractor, as represented by the +12 V connections in the schematic.  
         [0056]     Other aspects of windrower  10  include a propulsion driveline including fluid motors in connection, respectively, with drive wheels, which are differentially operated for effecting steering movements. The differential operation of the fluid motors of the driveline, as well as the travel speed, is effected by varying the displacement of fluid pumps in connection with the respective fluid motors of the driveline. A typical range of operating speeds of engine  68  of windrower  10  will be from about 1300 rpm, which represents a low speed, to about 2200 or 2300 rpm, which represents a typical normal operating speed.  
         [0057]     Because pump  66  of PTO driveline  50  is driven by engine  68 , operation of engine  68  at different speeds will result in operation of pump  66  at different speeds. This will cause pump  66  to generate different fluid flow outputs as the speed of the engine changes, if the displacement of the pump is not correspondingly adjusted for maintaining a particular fluid flow level. When a header  14  is installed, if an amount of fluid flow in excess of that required for operating the header is generated by PTO  38 , the excess flow will be directed through a diverter or pressure relief valve to tank. This is inefficient, as the generation of the excess flow requires engine power, and the fluid is unnecessarily heated, thereby subjecting it and related componentry to heat related problems, which is undesirable. As noted above, as an alternative, it would be desirable to have an automatic capability to determine an optimal fluid flow for operating a header  14  installed on windrower  10 , then to maintain that optimal fluid flow, regardless of variations in engine speed, that is, to provide a capability to vary the displacement of pump  66  as the speed of engine  68  changes, in a manner for maintaining optimal or near optimal fluid flow conditions.  
         [0058]     Referring also to  FIGS. 3 and 3   a , a flow diagram  80  illustrating steps of a method of the instant invention for calibrating PTO  38  for operation with a header, such as header  14 , is shown, for determining the control signals for providing a desired level of fluid flow to the header at any of a predetermined number or range of engine operating speeds. The steps of flow diagram  80  are preferably programmed in and executable by control module  60  at appropriate times, such as, but not limited to, when a header  14  is first installed, or after a repair or service affecting stored register values. When the operator invokes a calibration, or re-calibration, control module  60  will output a message on the screen of display device  78  that calibration is initiating, and request an action by the operator to enable the header  14 , via the two action PTO switch  74 . At block  82  control module  60  initiates the calibration routine. At block  84 , control module  60  sets the engine speed at one of a plurality of predetermined engine speeds. A first variable, being the electrical current range, is initialized to 16 ma as denoted by block  85 . With the engine at the selected speed, control module  60  applies or outputs an initial control signal to solenoid  54  having a predetermined initial signal value within a predetermined signal range for the engine speed, as denoted at block  86 . Control module  60  then monitors the resulting header speed, as denoted at block  91 . As denoted at decision blocked  92 , control module  60  then compares the operating speed of the header resulting from the outputted initial control signal to a predetermined target speed value for the header, here, which is preferably 725 rpm.  
         [0059]     Control module  60  will determine if the speed is greater than the target value, as denoted at decision block  92 . If yes, control module  60  will follow balloon B to proceed to calculate an incrementally changed control signal value, as denoted at block  93 , and following balloon A to block  87 , and output or apply the changed signal value to the pump solenoid  54 . If no, control module  60  will proceed following balloon C to calculate an incrementally changed control signal value, as denoted at block  94 , and output or apply the changed signal value to the pump solenoid  54 . Following balloon A, the electrical current range is then divided in half, as denoted by block  87 . The electrical current range is then compared to the minimum electrical current resolution required, 0.5 ma as denoted by decision block  88 . The process then repeats, starting at block  91  until the electrical current range is less than the minimum electrical current range resolution, 0.5 ma, as denoted by decision block  88 . When the minimum electrical current range resolution requirement is met, the electrical current value, corresponding to a header speed of 725 rpm at the present commanded engine speed, is stored as denoted by block  98 . Control module  60  then proceeds to determine if the signal map is complete, as denoted at decision block  89 . If not, control module  60  will proceed to set the engine speed at the next incremental value, as denoted at block  95 . Additionally, the electrical current range is re-initialized to 8 ma, as denoted by block  96 , and the present electrical current value is reduced by 2 ma, as denoted by block  97 .  
         [0060]     The process then continues, starting at block  91  until the full range of engine speeds are mapped, at which time the process concludes when the engine speed is equal to 2100 rpm, as denoted in decision block  89 .  
         [0061]     Control module  60  will preferably utilize a binary tree algorithm to increment or decrement, respectively, the control signal value so as to move the resultant header speed toward the target value, such that successive increments or decrements will be halved, and the header speed will be progressively moved toward the target value, until it is reached.  
         [0062]     As a result of execution of the calibration routines of the instant invention, registers of control module  60  will contain information representative of the electrical current values required to be directed to solenoid  54  for providing fluid flow for effecting operation of header  14  at the target operating speed thereof. These values can then be used by control module  60 , for determining new current values for achieving pump swash plate angles required for providing the optimal fluid flow to the header for a variety of engine speeds, such that flow diverted to tank by the diverter or pressure relief valve, and the attendant problems associated with it, are minimalized.  
         [0063]     Referring also to  FIGS. 4-28 , lines of code of an actual computer program embodying the above described steps of the method of the invention is disclosed. The notes accompanying the lines of code describe many features of the method of the invention.  
         [0064]     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 inventions. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.