Abstract:
Apparatus and a method providing a park brake for a propulsion system of an agricultural windrower having a FNR lever assembly including a FNR lever movable in relation to a neutral position in first and second directions, and a sensor for sensing positions of the FNR lever as the lever is moved and outputting signals representative thereof, the sensor being configured such that the signals outputted thereby are to have signal values within a predetermined range of values and/or which will change within a predetermined rate of change, a programmable control module in operative control of a park brake and programmed and operable for monitoring the signals and comparing the values of the signals to the predetermined range, and if the value of any of the signals is outside of the predetermined range, then automatically engaging the park brake.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/699,641, filed Jul. 15, 2005; U.S. Provisional Application No. 60/699,490, filed Jul. 15, 2005; and U.S. Provisional Application No. 60/699,943, filed Jul. 16, 2005. 
    
    
     TECHNICAL FIELD 
     The present invention relates to vehicular park brakes and, more particularly, to apparatus and a method providing automatic park brake operability for a propulsion system of an agricultural windrower. 
     BACKGROUND OF THE INVENTION 
     U.S. Provisional Application Nos. 60/699,641, and 60/699,490, both filed Jul. 15, 2005, and U.S. Provisional Application No. 60/699,943, filed Jul. 16, 2005, are incorporated herein in their entirety by reference. U.S. Pat. No. 6,901,729 is also incorporated herein in its entirety by reference. 
     Vehicles, such as, but not limited to, agricultural windrowers, can utilize control algorithms for translating input signals, for instance, from operator controlled input devices such as a forward-neutral-reverse (FNR) lever, also sometimes referred to as a multi-function-handle (MFH), to systems to be controlled thereby, such as the propulsion driveline. 
     It is therefore desirable to have a capability to monitor the performance of such control algorithms, to ensure that the input commands are being accurately and safely translated into machine operations and movements. This can be generally referred to as propulsion system safeing. It is also desirable to have the capability to determine or sense when a controlled system, such as a propulsion driveline, is no longer tracking a reference input signal sufficiently well. A degradation in the tracking capability can occur for any of several reasons, such as an interrupted or corrupted communication path, such as due to electrical noise and/or damage to a conductive path such as a wiring harness, physical wear or damage, and the like. It is also desirable to have the ability to determine or sense when the controlled system is overshooting or undershooting a system bounds. For instance, a propulsion system may drive a vehicle such as a windrower at a speed greater than a set speed. A system can overshoot (measured system output exceeds the desired output value) or undershoot (measured system output is less than the desired output value), which may indicate that a controller for the output has become unstable. Safeing in the instance of these conditions, will provide a manner of returning to a safe mode, which can include automatically going to a neutral mode, and/or shutting down the propulsion system. 
     It is also desirable to have the capability for providing an automatic park brake for ensuring that when the FNR lever is moved to the neutral position, or is already in the neutral position, the windrower is prevented from moving either in the forward, or the reverse direction. 
     SUMMARY OF THE DISCLOSURE 
     Accordingly, what is disclosed is apparatus and a method for providing an automatic park brake for a propulsion system of an agricultural windrower. 
     According to the invention, a FNR lever assembly includes a FNR lever having a neutral position and is movable in relation to the neutral position in a first direction and in a second direction opposite the first direction. At least one sensor is disposed and operable for sensing positions of the FNR lever as the lever is moved in the first and second directions and outputting signals representative thereof, and is configured such that the signals outputted thereby are to have signal values within a predetermined range of values. A programmable control module is connected with the at least one sensor for receiving the signals therefrom, and is connected in operative control of a park brake of the windrower, and the control module being programmed and operable for monitoring the signals and comparing the values of the signals to the predetermined range, and if the value of any of the signals is outside of the predetermined range, then automatically engaging the park brake. The park brake engagement can be immediate, or may be preceded by a controlled deceleration of the vehicle. 
     According to another aspect of the invention, the at least one sensor is configured such that the signals outputted thereby as the FNR lever is moved are to change at a rate within a predetermined range of rates of change; and the programmable control module is programmed and operable for monitoring the signals and comparing the rates of change thereof to the predetermined range of rates of change, and if any of the rates of change of the signals is outside of the predetermined range, then automatically engaging the park brake. 
     According to another aspect of the invention, the signals outputted by the at least one sensor are voltage signals, and the predetermined range comprises a voltage range, and the at least one sensor can be a potentiometer. 
     According to still another aspect of the invention, a relay is provided and energizable for providing power to the propulsion driveline, the control module being connected in operative control of the relay, and the control module being operable for engaging the park brake by de-energizing the relay. 
     According to still another aspect of the invention, the control module is programmed such that when the park brake is engaged and an engine of the windrower is operating, the control module is operable for disengaging the park brake when the FNR lever is in the neutral position and a steering mechanism of the windrower is set within a predetermined range from a straight ahead position. 
     In another aspect of the invention, the control module is programmed to engage the park brake if a start switch in connection with the control module is in an off position. And, a seat switch is operable for indicating when an operator is seated on a seat of the windrower, and the control module is programmed to engage the park brake if the FNR lever is in the neutral position and the seat switch indicates that an operator is not seated on the seat for longer than a predetermined time. The FNR lever assembly can also include a neutral switch in connection with the control module, the neutral switch having a first operating state when the FNR lever is in the neutral position and a second operating state when the FNR lever is out of the neutral position, and the control module is programmed to automatically engage the park brake if the at least one sensor is outputting signals representative of the FNR lever being in a position other than the neutral position and the neutral switch is in the first operating state, and if the signals outputted by the at least one sensor are representative of the FNR lever being in the neutral position and the neutral switch is in the second operating state. 
     According to still another aspect of the invention, the propulsion driveline includes a propulsion cylinder movable through a predetermined range of positions for effecting operation of the propulsion driveline within a predetermined range of speeds, and a sensor configured and operable for sensing a position of a propulsion cylinder and outputting signals representative thereof to the control module. Here, the control module is programmed to compare the signals representative of the positions of the propulsion cylinder to the signals representative of the positions of the FNR lever, and engage the park brake if the signals representative of the positions of the propulsion cylinder do not correspond to the signals representative of the positions of the FNR lever so as to indicate that the propulsion cylinder is sticking in a position. 
     The apparatus can also include a key switch and a park brake switch in connection with the control module, and wherein the control module is programmed to allow operation of the key switch for initiating engine starting only when the park brake switch is in a state for engaging the park brake. As another feature, the hard wired circuitry is configured such that the park brake must be re-released after a key-off/key-on cycle. 
     As a result, an advantage of the invention is that, to turn the start key on the operator must engage the parking brake. This is done by a momentary switch activation. 
     Another advantage is that the park brake must be disengaged to allow power to a propulsion control latching circuit which allows power to the propulsion controls. 
     As another advantage, the FNR lever must be moved out of the neutral position to latch a latching circuit for sending power to the propulsion controls. 
     Still further advantages include that the park brake automatically engages during certain fault conditions, including: if the start switch is turned off; the FNR lever is in neutral and the operator leaves the operator&#39;s seat for a predetermined time; the propulsion system is not engaging, or is stuck; there is a problem with the FNR sensor; the rate of change of the FNR sensor is out of an expected range; and if the relationship between the FNR sensor and the neutral switch do not match the expected states. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a side elevational view of a windrower of the type with which the invention may be used, including a header for severing crops from a field, mounted on a front end of the windrower; 
         FIG. 2  is a simplified diagrammatic representation of a propulsion driveline of the windrower incorporating aspects of the instant invention; 
         FIG. 3  is a schematic of circuitry of the propulsion driveline; 
         FIG. 4  is a schematic of other aspects of circuitry of the propulsion driveline; 
         FIG. 5  is another schematic of circuitry of the propulsion driveline; 
         FIG. 6  is another schematic of circuitry of the propulsion driveline; 
         FIG. 7  is a listing of code of a computer program incorporating steps of a preferred embodiment of the method of the invention; 
         FIG. 8  is a continuation of the listing; 
         FIG. 9  is a continuation of the listing; 
         FIG. 10  is a continuation of the listing; 
         FIG. 11  is a continuation of the listing; 
         FIG. 12  is a continuation of the listing; 
         FIG. 13  is a continuation of the listing; 
         FIG. 14  is a continuation of the listing; 
         FIG. 15  is a continuation of the listing; 
         FIG. 16  is a continuation of the listing; 
         FIG. 17  is a continuation of the listing; and 
         FIG. 18  is a continuation of the listing. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     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. Still further, in this description, the terms FNR lever, multi-function handle and MFH referred to the same item, and therefore are interchangeable. 
       FIG. 1  shows a self-propelled windrower  10  incorporating the apparatus and method of the invention; 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. 
     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 the frame  16  or chassis of the tractor  12 . The header may be of generally any suitable construction and design, and may include not only crop-harvesting mechanisms, but also crop conditioners such as elongate rolls  15 . Such attachment of the header  14  to the frame  16  is achieved through a pair of lower arms  18  (only the left one being shown, the right being generally the same) pivoted at one end to the frame  16  and at the other end to the header  14 , as well as through a central upper link  20 . 
     One or more cylinders, such as individual lift and flotation cylinders, or a single lift/flotation cylinder, interconnects the lower arm  18  and the frame  16  on each side of the header. 
     Typical features and operation of a system for controlling the lift and flotation functions for a header, such as header  14  depicted herein, are disclosed in U.S. Pat. No. 6,901,729, incorporated herein by reference. 
     Referring also to  FIGS. 2 ,  3 ,  4  and  5 , windrower  10  includes a propulsion driveline  22  controllably operable using operator controls for rotatably driving a left wheel  24  and a right wheel  26  for propelling windrower  10  over a ground or other surface. Hydraulic motors (not shown) in connection with each wheel  24  and  26 , respectively, are provided with fluid under pressure by hydraulic pumps  28 , for driving the wheels. The pumps  28  can be differentially controlled for supplying different and varying amounts of pressurized fluid to the hydraulic motors, for effecting desired movements of windrower  10 , including steering movements, as effected by operation of a rotatable and longitudinally movable propulsion rod  30  in connection with pintel arms  32  and  34  movable for controlling displacement of pumps  28  in the well-known manner. Steering commands are inputted to driveline  22  by an operator via an operator control which is a steering wheel  36  disposed in an operator cab  38  of windrower  10 . Steering movements of windrower  10  are effected by rotating respective wheels  24  and  26  at different speeds. Propulsion speed and direction commands are inputted to driveline  22  by an operator via an operator control which is a FNR lever  40  also disposed in cab  38 . 
     FNR lever  40  is configured to operate a suitable sensor or sensors operable for generating varying information or outputs representative of the position of lever  40  when lever  40  is manipulated or moved, including a rotary potentiometer  42  and a neutral switch  44 , each of which is connected to a tractor control module  46  via a suitable conductive path or paths  48 , which can be, for instance, a wire or wires of a wiring harness, an optical path, a wireless path, or the like. Movements of FNR lever  40  in relation to the neutral position will cause potentiometer  42  to output varying signals representative of the position of lever  40 , which signals comprise voltages. It is desired for these voltage signals to very precisely indicate the position of lever  40 , such that precise control of the forward and rearward movements of windrower  10  can be achieved. 
     For safeing purposes according to the instant invention, potentiometer  42  is mounted and configured so as to be jointly rotated by movements of FNR lever  40  to cause changing voltage outputs therefrom. 
     Neutral switch  44  is also mounted and configured such that movements of FNR lever  40  into the neutral position, and out of the neutral position, will cause changes in the operating state of switch  44 . Here, forward and rearward movements of FNR lever  40  from a generally straight up neutral position shown, with a park brake switch in a state to disengage the park brake, will effect a change of state of switch  44  which will be outputted to control module  46 , which will responsively power up the propulsion driveline, control module  46  controlling the propulsion speed of windrower  10  as a function of the voltage outputs of potentiometer  42 . Similarly, rearward movement of FNR lever  40  from the neutral position will effect a change of state of switch  44  outputted to control module  46  to effect operation of the propulsion driveline in the reverse direction if the park brake is in a disengaged state, and the voltage output of one or both of the potentiometers  42  will be used to control reverse speed. It is also desired that, when lever  40  is moved into the neutral position, the propulsion system be controlled to positively de-stroke or otherwise transition into a non-propelling state over time, such that abrupt stoppage does not occur. 
     Other operator controls include a park brake switch  50  also connected to tractor control module  46  via a conductive path  48 , and via another conductive path  48  to a key switch  52  and a start relay  54  in connection with a starter of engine  22  and with tractor control module  46 . A 2-speed switch  56  is connected to tractor control module  46  via another conductive path  48 . 
     Control module  46  is in connection with a dual rotary potentiometer  62  via a conductive path  48 , potentiometer  62  being operable for outputting information representative of the position of a propulsion cylinder  64 . Propulsion cylinder  64  is extendable and retractable by solenoids controlled by control module  46 , based on the voltage outputs of potentiometer  42 , to move propulsion rod  30  longitudinally for changing the stroke of the hydraulic pumps  28  via the angle of the pintel arms  32  and  34 , for effecting propulsion of the windrower. A rotary potentiometer  66  is operable for outputting information representative of the position of pintel arms  32  and  34  to module  46  via another conductive path  48 , providing information representative of differential stroking of pumps  28  to effect steering movements. Information representative of speed of respective wheels  24  and  26  is determined by reluctance speed sensors and communicated via conductive paths  48  to module  46 . Differences in the speed readings is also indicative of steering movements. 
     Other illustrated elements of propulsion driveline  22  include a park brake latch relay  70 ; a propulsion enable relay  72 ; a propulsion interlock relay  74 ; a brake valve solenoid  76 ; a ground speed high solenoid  78 ; propulsion cylinder position sensors  80  and  82  incorporating dual rotary potentiometer  62  ( FIG. 2 ); a pintel arm position sensor  84  incorporating rotary potentiometer  66  (also  FIG. 2 ); left and right ground speed sensors  86  and  88 ; a propulsion forward solenoid  90 ; and a propulsion reverse solenoid  92 . 
     As noted above, the instant invention utilizes control module  46  to monitor the propulsion command inputted thereto by potentiometer  42  indicative of the position of FNR lever  40 . Essentially, the output of only one of the potentiometers  62  is required for signaling propulsion commands or inputs, but two are used (dual Hall tracking) and the voltage outputs are continually summed. If the sum does not equal a predetermined value, here 5 V, it is determined that an error in the voltage signal of one or both of the potentiometers is determined. The output of potentiometer  62  is indicative of the position of propulsion cylinder  64  of the propulsion driveline  22 . The position of propulsion cylinder  64  (and thus the output of potentiometer  62 ) should, if normally operating, correspond to or track the inputted command from potentiometer  42 , modified by a transfer function, with consideration of normal deviations such as due to hysteresis, time lag in executing the propulsion commands, and the like. dv/dt (changing voltage over time) thresholding of the FNR potentiometer is used to identify/evaluate additional faults. 
     Reference input commands (e.g., voltages inputted through the position of FNR lever  40  by potentiometer  42 ) are matched with responsive system/hardware outputs (e.g., voltages outputted by potentiometer  62 ) to derive tracking errors e by control module  46 . Tracking errors e are processed to determine any faults. This is preferably done using an exponentially decaying integrator, also used for integration of current errors, to give the algorithm a forgetting type property wherein the most recent error signals are weighted more heavily than ones further in the past. A predetermined threshold is set on this exponentially decaying integrator to indicate when the controlled system is no longer tracking sufficiently well. When the value of the exponentially decaying integrator exceeds the threshold, appropriate action is taken to preserve the integrity and safety of the system, which can include outputting of a fault signal to the operator, an automatic system shutdown, or the application of the park brake according to the invention. 
     Another algorithm for monitoring the controller stability checks bounds. When the system is overshooting (measured system output exceeds the desired output value) or undershooting (measured system output is less than the desired output value) it is checked to make sure that the measured output value isn&#39;t at a corresponding saturation limit of the hardware, which would be an indication that the controller has become unstable, and the propulsion driveline shut down, including the automatic application of the park brake. 
     Essentially, if there is a fault, solenoids A and B ( FIG. 2 ) controlling the valve which directs hydraulic fluid to the chambers of propulsion cylinder  64  are de-energized, to allow the spring associated with propulsion cylinder  64  to take propulsion rod  30  to neutral, and the park brake is allowed to be applied. 
     Referring also to  FIGS. 7-18 , lines of code of an actual computer program embodying the steps of the method of the invention for providing automatic park brake operation is disclosed. The notes accompanying the lines of code describe many features of the method of the invention. In the code, the FNR lever is identified as the MFH. 
     As one mode of operation, if the signal values outputted by potentiometer is outside of a predetermined range, control module  46  is automatically operable for engaging the park brake. This can involve, for instance de-energizing park brake latch relay  70 . 
     As another function, control module  46  can be programmed such that when the park brake is engaged and an engine of the windrower is operating, the control module disengages the park brake (de-energizes or unlatches relay  70 ) when FNR lever  40  is in the neutral position and steering wheel  36  is set within a predetermined range from a straight ahead position, which range can be, for instance, but is not limited to,  800  in either direction from a straight ahead position. 
     As another function, control module  46  can be programmed to engage the park brake if start switch  52  is switched to its off position. The hard wired circuitry also requires re-release of the park brake after a key-off/key-on cycle. 
     As still another function, control module  46  can be programmed to engage the park brake if FNR lever  40  is in the neutral position and a seat switch indicates that an operator has not been seated on an operator seat of the windrower for a predetermined time. 
     In another mode, control module  46  is programmed to automatically engage the park brake if potentiometer  42  is outputting signals representative of FNR lever  40  being in a position other than the neutral position and neutral switch  44  is in an operating state representative of FNR lever  40  being in the neutral position; and if the potentiometer signals are representative of FNR lever  40  being in the neutral position and neutral switch  44  is in an operating state representative of FNR lever  40  being in other than the neutral position. 
     Also, if a comparison of the signals outputted by potentiometers  42  and  62  indicate that propulsion cylinder  64  is stuck, control module  46  can automatically engage the park brake. 
     Controller  46  can also be programmed to only allow operation of key switch  52  for initiating operation of propulsion driveline  22  when park brake switch  50  is in a state for disengaging the park brake. 
     Still further, as another mode, control module  46  can be programmed such that when the comparison of the rate of change of the FNR lever position and the rate of change of the propulsion cylinder position are different, the park brake can automatically be engaged. The park brake engagement can be immediate, or may be preceded by a controlled deceleration of the vehicle. Other features include the automatic engagement of the park brake (zero machine state) when electrical power is removed and/or if hydraulic power is removed. 
     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.