Abstract:
A control system for managing rotation of a bale loading arm in a bale loader in which a pair of sensors combined with a purposefully designed sensor target enable loading arm position to be efficiently derived by a controller in order to direct the actuator movements based upon loading arm position necessary for automated operation of a bale loading cycle. Additional inputs to the controller enable initiation of a bale loading cycle to be automatically initiated. The controller may also determine when a complete bale wagon load is achieved and automatically direct loading arm motions necessary to configure the bale wagon for transport.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to agricultural bale handling and hauling machines, and more particularly to such a control system for a bale wagon that automates the loading of large bales onto a bale wagon. 
         [0002]    A large proportion of the resources and time of the agricultural industry is directed toward the production of feed for animals, and most specifically to the production of baled stem and leaf crops such as hay. The conventional process is to cut and condition the crop with a windrower, deposit it on the ground to dry, bale the crop when appropriately dry, and then position the bales in stacks for storage or transportation. High labor requirements and increasing costs of manual handling of bales have caused a growing number of commercial growers to abandon their small square bale operation for a large bale package, such as round bales, or large rectangular bales 3′×3′, 3′×4′, or 4′×4′ in cross-section. Due to the large size of the bales, there is a need for equipment which can pick up the bales in the field, accumulate a load of bales, and transport them to a remote storage area where the accumulated bales can be unloaded. Also, such equipment must be flexible in the ability to deal with bales of varying sizes. Furthermore, it is important that the bale handling equipment be able to arrange and control the position of bales on the transporter bed after the bales have been picked up. 
         [0003]    Commercial haulers prefer large square bales over small square bales because they can be retrieved from a field and loaded for a cross-country trip in less than an hour. Large rectangular bales are loaded onto flat-bed trucks or semi-trailers directly in the field at about 20 tons per man-hour. Transporting larger loads of bales reduces fuel usage and the time required for bale handling. It is these large rectangular bales that have become increasingly popular over the last several years, and to which this invention is most concerned. 
         [0004]    The Mil-Stak® big bale loading attachment was developed as a way incorporate big bale handling capability on self-propelled or pull-behind bale wagons. The Mil-Stak® big bale loading attachment comprises a bale clamping apparatus connected to a pivoting lifting arm. The lifting arm is coupled at one end to the bale wagon for pivotal motion about a single axis, the axis being angled relative to the bale wagon. Loader arm movement is accomplished by a single actuator acting on a lever arm to pivot the lifting arm through approximately 180 degrees of motion. A second actuator actuates the clamping apparatus. The actuators are manually controlled by an operator from the cab of the bale wagon from where he can observe the bale position and manage actuator motions accordingly. 
         [0005]    The Mil-Stak® bale loading attachment was developed as a retrofit solution for a bale wagon enabling big bales to be efficiently gathered from the field and loaded onto the bale wagon. The Mil-Stak® loading attachment replaces the bale loading normally supplied with a bale wagon and allows big bales to be loaded onto the bale wagon. The replacement also renders certain bale handling operations necessary for small bale loading unnecessary, so the bale wagon must be operated in a manual mode when using the Mil-Stak® attachment. The Mil-Stak® attachment requires and offers minimal controls accessible to the operator through a small electromechanical operator interface requiring manual operator input for all loader movements. Manual control introduces difficulty in that the single hydraulic actuator used to reposition the bale loader arm requires reversing the direction of the actuator as the loader arm reaches an apogee in the pivotal motion. The operator must, therefore, precisely actuate a switch which causes the actuator to reverse its direction of movement at the loader arm apogee, allowing momentum to move the loader arm through the apogee position smoothly. The inertial effect of a bale in the clamping apparatus assists the operator through the transition during the loading sequence; however, returning the loading arm to retrieve the next bale requires moving through the apogee position without the inertial assist of a bale. 
         [0006]    In addition to managing operating of the bale loading actions, the operator must also operating the bale wagon itself, guiding it around the field to position bales on the ground within reach of the bale clamping apparatus and controlling movement of the bale tilting table that creates the stack of bales on the load floor. The result is that significant operational demands are placed on the bale wagon operator which lead to increased fatigue and ultimately affect productivity. It would be advantageous to provide a control system to automate portions of the Mil-Stak® bale loading cycle. Further advantages would be realized with a control system that operably coupled several portions of the loading cycle and provided a complete control system capable of automating the entire bale loading sequence up to and including preparation for bale load transport. 
       SUMMARY OF THE INVENTION 
       [0007]    Accordingly, the present invention, in any of the embodiments described herein, may provide one or more of the following advantages: 
         [0008]    It is an object of the present invention to provide a control system for a big bale loader on a bale wagon capable of controlling the loader arm and bale clamping apparatus throughout the entire loading cycle. 
         [0009]    Another object of the present invention is to provide a position sensing mechanism for providing input to a control system for a big bale loader apparatus that will ascertain the position of the loading apparatus thereby enabling control of the apparatus regardless of the initial position of the apparatus. 
         [0010]    It is another object of the present invention to provide a control system and position sensing mechanism for a big bale loading apparatus that will handle interruption of the automatic cycle without requiring the apparatus to be moved to a known initial position. 
         [0011]    It is another object of the present invention to provide a sensing and control system for a big bale loading apparatus that monitors and limits bale clamping pressure to limit damage to the bales. 
         [0012]    Yet another object of the present invention is to provide a sensing device in the bale clamping mechanism that can be used to initiate the bale clamping operation. 
         [0013]    It is yet another object of the present invention to provide a control system for a bale loading apparatus that operationally couples discrete action initiation signals and corresponding actions into a unified, controlled operational cycle requiring minimal operator input. 
         [0014]    It is yet another object of the present invention to provide a control system for a bale loading apparatus that operationally couples discrete action initiation signals for bale grasping and loader arm movement into a unified, controlled operational cycle requiring minimal operator input. 
         [0015]    It is a still further object of the present invention to provide a sensing device for monitoring the position of the loading arm of a bale loading apparatus as the arm is raised from a fully lowered position and as the arm is lowered from a fully raised position. 
         [0016]    It is a still further object of the present invention to provide a control system receiving position input from position sensing devices that is capable of controlling movement of the loading arm of a bale loading apparatus as is travels through an apogee in its travel path as the direction of motion of an actuator must be reversed. 
         [0017]    It is a still further object of the present invention to provide a sensing and control system for a bale loading apparatus that is durable in construction, inexpensive of manufacture, carefree of maintenance, easily assembled, and simple and effective to use 
         [0018]    These and other objects are attained by providing a control system for managing rotation of a bale loading arm in a bale loader in which a pair of sensors combined with a purposefully designed sensor target enable loading arm position to be efficiently derived by a controller in order to direct the actuator movements based upon loading arm position necessary for automated operation of a bale loading cycle. Additional inputs to the controller enable initiation of a bale loading cycle to be automatically initiated. The controller may also determine when a complete bale wagon load is achieved and automatically direct loading arm motions necessary to configure the bale wagon for transport. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0019]    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: 
           [0020]      FIG. 1  is a front perspective of a bale wagon having a bale loader of the type on which the present invention is useful; 
           [0021]      FIG. 2  is a partial perspective view of the bale loading apparatus incorporating one embodiment of the present invention showing the loading apparatus in the fully lowered position; 
           [0022]      FIG. 3  is a partial perspective view of the bale loading apparatus of  FIG. 2  showing the apparatus in the fully raised position; 
           [0023]      FIG. 4  is a partial section view of a portion of the bale load loading apparatus of  FIG. 2  showing the position sensing system while the bale loading apparatus is in the fully lowered position; 
           [0024]      FIG. 5  is a partial section view of the position sensing system shown in  FIG. 4  while the bale loading apparatus is in an intermediate position at which point the mechanism is at top dead center, referred to as an intermediate transition position; 
           [0025]      FIG. 6  is a partial section view of the position sensing system shown in  FIG. 3  while the bale loading apparatus is in the fully raised position; and 
           [0026]      FIG. 7  is a simplified schematic of the control system embodying the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    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. Likewise, “forward” and “rearward” are determined by the normal direction of travel. “Upward” and “downward” orientations are relative to the ground or operating surface as are any references to “horizontal” or “vertical” planes. 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 be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures. 
         [0028]    Referring now to the drawings and, particularly, to  FIG. 1 , a side view of a bale wagon incorporating the principles of the instant invention can be seen. The present invention is also useful on pull-behind bale wagons (bale wagons towed by a separate tractor or prime mover). Thus while the description herein is based upon application of the bale loader to a self-propelled wagon, the principles of the instant invention are equally useful on pull-behind bale wagons and should be construed as such. The bale wagon, generally designated  10 , is provided with a mobile chassis generally designated  12  having wheels  14  and an operator cab  16 . The cab  16  also includes the various controls both for the operation of the bale wagon as a vehicle and for the operation of the various bale loading and stacking portions of the machine. This bale wagon is of the self-propelled type; however, the primary source of power and some of the drive mechanism have been removed to simplify the drawing for purposes of clarity. The bale wagon  10  has the ability to function as an off-highway agricultural vehicle capable of good maneuverability and low speed for picking up ales, yet transport over the road from field to field. 
         [0029]    The bale wagon  10  is generally described as a three-table bale wagon and is normally provided with a bale loader adapted to pick small bales up successively from the field and deposit them on a first table (not shown), also referred to as a cross-conveyor, for arrangement in a tier. As adapted in the present invention, bale loader  30  is configured to pick big bales  5  up successively and place them on a second or tilting table  22  where they are arranged prior to loading onto a third table, referred to as the load rack  24 . The first table is not utilized when big bales are being loaded as a single big bale  5  (approximately  8  feet in length) typically spans the transverse width of the bale wagon. Bale loader  30 , to be described in further detail below, is mounted to the forward portion of chassis  12 , behind cab  16 . Bales on the tilting table  22  are moved onto the load rack  24  by a pivoting movement of the tilting table (illustrated in  FIG. 1 ). One, two, or three big bales (depending on the desired stack configuration) are typically simultaneously moved from the tilting table to the load rack resulting in one or two bales stacked upon the other when positioned on the load rack. When a sufficient quantity of bales is present in the load rack, the bale wagon is used to transport the bales to a location where the bales are to be stacked. The load rack  24  is pivotally connected to the chassis allowing it to be tilted to a near-vertical orientation, allowing the bales therein to be placed in a stack on the ground. Bale wagons of this type are generally well known in the art. Additional descriptive details of the bale wagon are provided in U.S. Pat. No. 2,848,127 issued to Grey, and U.S. Pat. No. 4,203,695, issued to Wynn, et al., the descriptive portions of which are incorporated herein by reference. 
         [0030]    Referring now to  FIGS. 1 through 3 , bales are moved from the ground to the tilting table  22  by the bale loader, generally indicated by reference number  30 . Bale loader  30  is mounted to chassis  12  and includes a pivoting bale loading arm  32  coupled to an elongate shaft  31 , the shaft  31  having opposing first and second ends. Shaft  31  is rotationally supported by chassis  12  in a conventional manner using bearings, bushings or other known means for radially and axially supporting a rotating shaft. Bale loading arm  32  is connected to a first end of shaft  31  and extends radially therefrom to a pickup end  33 . The connection between shaft  31  and bale loading arm  32  is configured to prevent relative movement therebetween such that bale loading arm  32  will be pivoted about axis  100  as shaft  31  rotates. Shaft  31  is oriented such that its rotational axis  100  is angled relative to the longitudinal axis  110  of the bale wagon, typically near 45 degrees, in order to provide proper bale positioning, retrieving bales from the field forwardly and outwardly and placing them on the tilting table rearwardly and inwardly by motion of the bale loading arm  32 . A lever arm  36  is connected to the second end of shaft  31  and configured to extend radially therefrom creating a moment arm on which actuator  40  can act to rotate the shaft  31 . In the embodiment presented, actuator  40  is a single-acting hydraulic cylinder which creates the need to reverse the direction of movement of the cylinder rod as the loading arm passes through the apogee position. 
         [0031]    Bale pickup is accomplished using a bale grasping mechanism  60  which is connected to the pickup end  33  of the bale loading arm  32 . Grasping mechanism  60  comprises a base frame  61  to which are connected a pair of spaced-apart grasping arms  62 , each arm being movably connected to the base frame to allow selective clamping of a bale therebetween. In operation, grasping arms  62  are initially positioned generally parallel to the ground and oriented generally parallel to the direction of travel of the bale wagon. The operator steers the bale wagon until the bale to be loaded is aligned in the space between the grasping arms  62 . As the bale wagon moves forward, the grasping arms  62  are positioned alongside the bale until an end of the bale contacts bumper  65 . Bumper  65  typically includes springs or similar means to lessen the impact forces of the bale contact with the base frame. Bumper  65  may also include a contact switch to provide a control input to initiate a bale loading cycle, described in greater detail hereinafter. Grasping arms  62  are then moved towards one another to grasp the bale for lifting. 
         [0032]    The range of motion of the bale loading arm  32  is approximately 180 degrees about the arm pivoting axis  100 . The range of motion may be limited by positive travel stops, shown in  FIGS. 4  though  6 , as lower travel stop  36  and raise travel stop  37 . The travel stops are shown adjacent to the actuator end of shaft  31 , but may be positioned to interact with rotation of the bale loading arm  32  or other movable portion of the bale loader with equivalent functionality. For reference purposes herein, a zero rotational position reference is established when the bale loading arm is in the fully lowered position, as it would be when retrieving a bale from the field (the position shown in  FIGS. 1 and 2 ). As the bale loading arm is raised, such as when picking up a bale from the field, it approaches a zenith position after approximately 120 degrees of rotation. Actuator  40  receives pressurized fluid for movement which elevates the bale grasping mechanism  60  (movement from 0 toward 120 degrees or from 180 degrees toward 120 degrees). At the zenith position, actuator  40  has reached a travel limit and its direction of travel must be reversed in order to continue rotation of the bale loading arm, thus this position is also referred to herein as the intermediate transition position. Motion which de-elevates the bale grasping mechanism  60  requires release of hydraulic fluid from actuator  40  (movement from 120 toward 180 degrees or from 120 degrees toward 0 degrees). Further rotation of the bale loading arm is necessary to position the bale on the tilting table  22 . The bale loading arm is considered to be in the fully raised position when the bale is placed on the tilting table, requiring approximately 180 degrees of rotation from the fully lowered position. 
         [0033]    Now referring to  FIGS. 4 through 7 , monitoring of the position of the bale loading arm is accomplished by a position sensing system  50  which comprises a first sensor  52 , also referred to as the raise sensor, a second sensor  54 , also referred to as a lower sensor, and a target  55  with a raising edge  56  and a lowering edge  57 , each edge being generally defined by a radius extending from axis  100 , span about 120 degrees of rotation of the shaft relative to a fixed point. Target  55  is configured to rotate in unison with shaft  31  while the first and second sensors remain in a fixed position. As the shaft and target rotate, the target will be sensed by neither, one, or both of the sensors. The raise and lower sensors  52 ,  54  are positioned approximately 92 degrees apart in the rotational plane of the target  55 . Mounting slots  59  allow the position of raise and lower sensors  52 ,  54  to be adjusted to fine-tune operation of the bale loader control system. Position sensing system  50  provides input signals  201 ,  202  to a bale loading controller  200  enabling the position and direction of motion of the bale loading arm  32  to be determined. The sensors  52 ,  54  are configured to produce a binary output signal (input signals  201 ,  202 ); each sensor input signal to the controller has a first value (high) if the sensor detects the presence of the target in its sensing view and a second value (low) when the presence of the target is not detected. As the raising edge  56  and/or lowering edge  57  pass through the sensing view for each sensor, the output signal of the sensor will change states. It is the change in state that enables controller  200  to determine the rotational position of the shaft  31  and thus the bale loading arm  32 . By comparing the order in which each sensor signal changes states, the position and direction of movement of the bale loading arm can be determined by the controller. As it is the change of state of the sensors that is used for input to the controller, one skilled in the art will recognize that the target and sensors can be re-oriented to reverse the target profile and/or the binary value of the output signals without departing from the intent of the present invention. 
         [0034]    For reference, the bale loading arm in the fully lowered position as shown in  FIG. 4  is established as 0 degrees and clockwise rotation as shown in  FIGS. 4 through 6  is the positive direction. In the fully lowered position, the bale loading arm  32  is extended away from the bale wagon as it would be positioned to grasp a bale in a field to initiate a bale loading sequence. At or near the fully lowered position, neither the raise nor lower sensors  52 ,  54  can sense the target  55 . Once initiated, actuator  40  is pressurized to begin moving lever arm  36  to rotate shaft  31  in a clockwise direction which corresponds to moving the bale loading arm  32  from the fully lowered position towards the raised position. 
         [0035]    As the shaft  31  rotates, the raising edge  56  of target  55  first covers the lower sensor  54 , positioned at approximately 14 degrees. A first signal  202  generated by the lower sensor when the raising edge  56  first encounters can be used to signal controller  200  that the bale loading arm  32  is moving in the raising direction. 
         [0036]    After approximately 92 degrees of continued rotation of the bale loading arm, raising edge  56  will cover the raise sensor  52  and the bale loading arm will be positioned at approximately 106 degrees (approaching top dead center of the rotation). Since the target  55  spans approximately 120 degrees, the target will be in view of both the raise and lower sensors  52 ,  54 . A second signal  201  generated by the raise sensor  52  combined with the first signal  202  from the lower sensor  54  can be used to signal the controller  200  that the bale loading arm is approaching its apogee (top dead center) and that the direction of travel of actuator  40  must be reversed in order to continue the bale loading motion. Controller  200  manages actuator  40  using actuator control valve  210 , the position of which is controlled by actuator signal  211 . 
         [0037]    When the bale loading arm continues rotation and reaches a position approximately 134 degrees from the fully lowered position, the lowering edge  57  passes the lower sensor  64  so that only the raising sensor  62  views target  55  and first signal  202  changes state. At this point, the bale in the grasping mechanism  60  is approaching the tilting table  22 . The change in the lower sensor  54  state while the raise sensor  52  is still sensing the target can be used by the controller  200  to initiate release timing of the bale grasping apparatus  60  so that the bale may be released and deposited on the tilting table as it reaches the tilting table surface. The raise sensor  52  continues to sense the target  55  as the bale loading arm moves to the fully raised position, 180 degrees from the fully lowered position. 
         [0038]    As the rotation of the bale loading arm is reversed, the target  55  remains in view of raise sensor  52 . Once the loading arm reaches a position at approximately 134 degrees, approaching the apogee in the lowering direction, lowering edge  57  passes over lower sensor  54  so that target  55  is in view of both sensors. As in the raising process, the presence of first and second signals  202 ,  201 , respectively, indicates that the direction of travel of actuator  40  will soon need to be reversed. 
         [0039]    Further rotation of the loading arm in the lowering direction results in the raising edge  56  of the target passing the raise sensor  52  as the loading arm reaches a position of approximately 106 degrees, just past the top dead center (zenith) position. This position is useful when the bale wagon  10  has been completely filled with bales  5  and is being prepared for transport. The normal transport position is with the tilting table  22  in the raised position against the bales in the load rack  24  and the bale loader  30  in the fully raised position. In order to reposition the tilting table  22 , the bale loader  30  must be at least partially lowered in order to clear the tilting table  22 . Rather than delay preparation for transport while the bale loader arm  32  travels from the fully raised position (where it would be having loaded the final bale for the load) to the fully lowered position to clear the tilting table and then return to the fully raised position for transport, an intermediate position that allows tilting table  22  movement without requiring the bale loader to travel to the fully lowered position saves time while the bale wagon is properly configured for transport. 
         [0040]    As the bale loading arm  32  approaches the fully lowered position, the raising edge  56  will finally pass over the lower sensor  54  so that neither sensor views the target  55 . At this point, time-based lowering of the lifting arm is allowed to continue until the lifting arm returns to the fully lowered position. When the lifting arm returns to the fully lowered position, the bale loading process is complete and the bale loader  30  is ready to pick up the next bale. 
         [0041]    The control system comprises controller  200  which manages the bale loading process and enables automated loading of a bale. Controller  200  is programmed and configured to receive inputs signals, perform computational operations based on those input signals, and generate output signals for directing movement of actuators in the bale loader  30  and the bale wagon  10 . The controller may be a separate unit dedicated to managing operation of the bale loader  30  or its function may be integrated into a controller tasked to manage the entire operation of the bale wagon. Controller  200  receives first and second input signals  201 ,  202  from raise and lower sensors  52 ,  54 , respectively, indicating whether the target is in view of each sensor. From the sensor information, the controller  200  can determine the position of the bale lifting arm  32  within certain ranges and generate appropriate output signals  211 ,  221  to the lifting actuator  40  control valve  210  or the grasping actuator  68  control valve  220 , respectively. Position indication signals at 106 and 134 degrees along with inputs from sequential actions enable the controller  200  to initiate control output signals to actuator control valve  210  so that changes in actuator  40  movement necessary to move the bale loading arm through the intermediate transition position may be managed. Additionally, the controller is configured to monitor the position of the bale lifting arm, even when the bale loader is being manually operated, so that the controller can resume automatic control with the lifting arm in any position without having to reposition the lifting arm to a known control initialization position. This allows control to be easily be moved between manual and automatic modes. 
         [0042]    The bale loading process may be manually initiated through an operator input apparatus  250 , initiated upon sensing that a bale has been properly grasped in the grasping apparatus by a pressure sensor  222  monitoring grasping actuator  68  pressure and generating grasping input signal  223 , or the process may be automatically initiated upon sensing the presence of a bale within the grasping apparatus  60  by using a contact sensor  69  incorporated into the grasping apparatus to initiate the bale grasping operation by contact signal  226  followed by the bale loading operation. 
         [0043]    Controller  200  may also include a counting function to monitor the number of bale loading cycles completed. The counter is needed to coordinate operation of the tilting table  22 , which requires a full or partial tilting movement with each bale placement on the table  22 . With an input for the bale capacity of the bale wagon (dependent upon the desired bale stack configuration), either built into the controller function or selectively input by an operator using the operator input apparatus  250 , the controller  200  can determine when the maximum load of the bale wagon has been reached and, using the position function that enables a partial lowering of the bale lifting arm described above, coordinate movement of the bale lifting arm to an intermediate position at which the tilting table  22  can be repositioned for transport and then direct the bale lifting arm  32  to return to the fully raised position for transport. Tilt table position is determined by well known means resulting in a tilt table position signal  241  which is provided to controller  200 . Controller  200  the operationally coordinates movement of the tilting table  22  with the bale loader  30  by providing the tilt table position signal  242  which directs movement of the tilt table, generally by directing movement of the tilt table hydraulic actuators similar to the methods discussed above with respect to the bale loading arm actuator control. 
         [0044]    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.