Abstract:
A round baler is provided with a bale-forming chamber that is surrounded by a pressing apparatus in the form of a single pressing belt or several pressing belts arranged one next to the other, wherein the pressing apparatus contacts a roller that can be driven and freely co-rotating rollers, of which at least one pre-tensioned roller is loaded by pre-tensioning apparatus in the sense of tightening the pressing apparatus such that it pre-tensions the pre-tensioned roller more strongly the farther this roller moves in a direction for loosening the pressing apparatus. The two ends of the pre-tensioned roller are each pre-tensioned by the pre-tensioning apparatus and can move independently of each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Pursuant to 35 USC §119, this application claims the benefit of and priority to German patent application no. 102015211034.6, filed on Jun. 16, 2015, which is herein incorporated by reference in its entirety. 
       FIELD OF THE DISCLOSURE 
       [0002]    The disclosure relates to a round baler with a bale-forming chamber and at least one pre-tensioned roller. 
       BACKGROUND 
       [0003]    Round balers are used to form bales from stalk-shaped agricultural harvested produce. Such round balers have a bale-forming chamber and associated pressing means. After completing and optionally wrapping a bale with mesh, twine, or a film, the bale is ejected out the back of the bale-forming chamber. 
         [0004]    In many round balers, especially in those with a variable bale size, the bale-forming chamber is partially or completely surrounded by one or more pressing belts. The pressing belt or belts wrap around the rollers, of which at least one can be driven. Some of the rollers are supported on the frame of the round baler and others can move relative to the frame, in order to adapt the bale-forming chamber to the gradually growing bale and to allow an ejection of a completed bale. 
         [0005]    The partially driven, partially freely co-rotating rollers extend transverse to the forward direction and to the axis of the bale. Typically, a number of narrower pressing belts is distributed across the width of the bale-forming chamber or a single, wide pressing belt is used (cf. U.S. Pat. No. 5,941,168 A1). 
         [0006]    Because a non-uniform loading of harvested produce across the width of the bale-forming chamber or a shifting of the harvested produce toward one side while working on a hill leads to a lateral displacement of the pressing belt, which can result in undesired rubbing of the pressing belt against the side wall of the round baler and incorrect measured values of a sensor interacting with the pressing belt for detecting the bale size, guides for the pressing belt have been proposed that are made from rigid elements contacting the pressing belt on the side (U.S. Pat. No. 5,261,323 A1). It has also been proposed to attach rings that project in the radial direction on one of the rollers, so that the individual pressing belts each run between two rings (U.S. Pat. No. 3,992,987 A1). It has further been proposed to implement the lateral guidance of the belt through grooved rollers that contact the belts on the side directly before a driven roller (DE 10 2011 003 727 A1). 
         [0007]    U.S. Pat. No. 3,687,273 A describes a conveyor belt in which the lateral position of the belt is registered by rollers contacting the belt on the side. The rollers control a holder that is supported by springs on the frame on which a deflection roller of the belt is supported, such that the belt is pre-tensioned more strongly by the deflection roller on the side toward which the belt is running. In this way, the belt should be guided centrally on the deflection roller. 
         [0008]    The known means for the lateral guidance of pressing belts causes increased friction of the belt on the guidance means, which requires, on one hand, drive energy and, on the other hand, results in wear of the belt. 
       SUMMARY 
       [0009]    The present disclosure provides a round baler which does not have the disadvantages mentioned above or has them at a reduced degree. 
         [0010]    A round baler is provided with a bale-forming chamber that is surrounded by a pressing apparatus in the form of a single pressing belt or multiple pressing belts arranged directly next to each other or forming only relatively small gaps. The pressing apparatus contacts a roller that can be driven and freely co-rotating rollers on which at least one pre-tensioned roller is loaded by pre-tensioning apparatus in the sense of tightening the pressing apparatus. The pre-tensioning apparatus are constructed such that the pre-tensioned rollers are pre-tensioned more strongly the farther these move in a direction leading to the loosening of the pressing apparatus. Consequently, they have an increasing characteristic curve, like what can be achieved with a hydraulic cylinder controlled by a spring or a position-detecting sensor. The two ends of the pre-tensioned rollers are each pre-tensioned by associated pre-tensioning apparatus and move independently of each other. 
         [0011]    The pressing apparatus consequently revolves around the rollers pre-tensioned separately from each other on both ends. If the pressing apparatus is now tensioned non-uniformly across its width—for example, due to a non-cylindrical bale—which could have the result that it deviates from its desired position on the pre-tensioned roller, the pre-tensioned roller is deflected against the pre-tensioning of the pre-tensioning apparatus more toward the larger side of the bale (in the direction leading to the loosening of the pressing apparatus) than toward the other side. This increases the pre-tensioning force of the pre-tensioning apparatus on the larger side of the bale (due to the increasing characteristic curve of the pre-tensioning apparatus), which in turn has the result that material of the bale and, if it has left its desired position, also the pressing apparatus move in the other direction until they have again reached their desired positions. In this way, without lateral guides and without means for registering the position of the pressing apparatus, it is achieved that the pressing apparatus remain in its desired lateral position on the pre-tensioned roller also for non-cylindrical bales and thus also on the other rollers. 
         [0012]    The pre-tensioned roller can be mounted on both ends on a holder that is hinged so that it can pivot on the frame of the round baler and is coupled with the pre-tensioning apparatus. 
         [0013]    The positions of the ends of the pre-tensioned roller can be detected by a sensor. The signals of the sensors can be displayed to the operator, so that he or she can steer the tractor and the baler over the field in the sense of forming a cylindrical bale, or can be used by an automatic steering system in the mentioned sense. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    In the drawings, an embodiment that is described in more detail below is shown, wherein the reference symbols should not be used for limiting the features of the claims. Shown are: 
           [0015]      FIG. 1  a schematic side view of a round baler, 
           [0016]      FIG. 2  a schematic front view of a pre-tensioned roller of the round baler for proper running pressing apparatus, and 
           [0017]      FIG. 3  a schematic front view of a pre-tensioned roller of the round baler for pressing apparatus deviating toward the left from the proper path. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIG. 1  shows a schematic side view of a round baler  10 , which includes a frame  12  that is supported on wheels  14  and can be pulled by means of a tow bar  82  by a not-shown tractor over a field in its forward direction that runs, in  FIG. 1 , toward the left, in order to collect harvested produce by means of a not-shown pick-up device and to feed it via an inlet channel  20  into a bale-forming chamber  16 , in which a bale  18  is then successively formed. The bale-forming chamber  16  is bounded by rollers  22 ,  24 ,  26  that are supported so that they can rotate in the frame  12  and are adjacent to the inlet channel  20 . In addition, the bale-forming chamber  16  is bounded by an endless pressing apparatus  64  in the form of one or more belts arranged laterally one next to the other, which encloses or enclose additional rollers  28 ,  30 ,  32 ,  34 ,  36 ,  38 ,  40 ,  42 ,  62 , and  44 , as well as the roller  22 , partially, of which one (e.g., the roller  30 ), multiple, or all rollers are driven to rotate during the formation of a bale  18  and the others co-rotate freely. The rollers  28 ,  30 ,  38 ,  40 , and  22  are supported so that they can rotate in the frame  12 , i.e., apart from their rotation about the longitudinal axis, they do not move relative to the frame  12 , when a bale  18  is being formed. 
         [0019]    The rollers  32  and  36  are each mounted on their two ends on a carrier  50  that is hinged on its upper end so that it can pivot about an axis  74  on the frame  12 . The carrier  50  is coupled rigidly with an arm  52  that is pre-tensioned by means of a hydraulic cylinder  54 . The carrier  50  thus moves during the creation of a bale  18  against a pressure present in the piston rod chamber of the hydraulic cylinder  54  set upward, if a bale  18  is created and the bale-forming chamber  16  gradually grows larger in that the pressing apparatus  64  bounding the bale-forming chamber  16  deflect upward and backward, as is shown in  FIG. 1  with dashed lines. 
         [0020]    The rollers  42 ,  62 , and  42  are mounted on a pivot part  46  so that it can be pivoted backward and upward about an upper axis  76  by an actuator  48  in the form of a hydraulic cylinder, in order to eject a bale  18  from the bale-forming chamber  16 . The bale  18  then rolls onto an unloading ramp  78  and onto the ground. 
         [0021]    The pre-tensioned roller  34  is supported so that it can rotate on a holder  58 , which is hinged on the frame  12  so that it can pivot about an axis  56  approximately in its center and is pre-tensioned by a spring  60 . The spring  60  has the goal of tightening the pressing apparatus  64 , in that it pulls the pre-tensioned roller  34  upward in the counterclockwise direction, and it is pulled farther the more the pre-tensioned roller  34  moves downward, i.e., in the direction of loosening of the pressing apparatus  64 . On the other side of the round baler  10 , there is also another holder  58  on which the pre-tensioned roller  34  is supported so that it can rotate, and another spring  60 , wherein this holder and spring are independent from the components (holder  58  and spring  60 ) shown in  FIG. 1  and thus can move independently of these parts. 
         [0022]    The round baler  10  is known essentially from EP 1 396 187 A1 and EP 1 364 574 A1, whose disclosure is incorporated in the present document through this reference. 
         [0023]    The function of the roller  34  pre-tensioned on its two ends independently from each other is shown in  FIGS. 2 and 3 . In  FIGS. 2 and 3 , the holder  58  is not shown for reasons of illustration, so that the springs  60  in the schematic diagrams directly attach to the axis of the pre-tensioned roller  34  and pull the latter upward on both ends (as is the case also in  FIG. 1 ). In the situation according to  FIG. 2 , the pressing apparatus  64  run symmetric to the pre-tensioned roller  34 . 
         [0024]    If the bales  18  that are formed are not cylindrical, but conical, e.g., due to non-symmetrical feeding of the harvested produce into the bale-forming chamber  16  or feeding on the side of a hill, this leads to the situation according to  FIG. 3 , in which the left side of the bale  18  has a larger diameter than its right side. The bale  18  thus tensions the pressing apparatus  64  more strongly to the left than to the right. Because the pressing apparatus  64  is essentially not elastic overall, it cannot absorb even the different tension, but instead pulls the roller  34  farther to the left against the downward force of the spring  60  than to the right. Thus the left side of the roller  34  moves downward and the left spring  60  is more strongly tensioned than the right spring  60 . Here, the pressing apparatus  64  can move slightly to the left on the roller  34 , as shown, exaggerated for illustrative purposes, in  FIG. 3 . The resulting forces acting on the pressing apparatus  64  are indicated in  FIG. 3  by arrows: The farther it moves to the left, the greater the force becomes pulling the pressing apparatus  64  upward, because the left spring  60  pulls the roller  34  upward more strongly than the right spring  60 . That leads to a force component that pulls the pressing apparatus  64  on the roller  34  back to the right. Simultaneously, the material in the baler chamber  16  is also moved to the right, because it is compressed by the pressing apparatus  64  more strongly in the left part of the baler chamber  16  than in the right part. As a result, the situation according to  FIG. 2  is finally obtained again. 
         [0025]    If the pressing apparatus  64  were to deviate toward the right, the function would be analogous, only in the other direction. 
         [0026]    For detecting the active spring forces, two sensors  66  are used, each of which detect the rotational position of the holder  58  about the axis  56  on another side of the round baler  10 . 
         [0027]    The spring forces depend on the tensile force in the pressing apparatus  64  that depends, in turn, on the size of the bale  18 . The sensors  66  are designed, in particular, as potentiometers or some other kind of rotational angle sensor. The sensors  66  are connected to an evaluation circuit  70 . Because the sensors  66  can move independently of each other, in the event of non-cylindrical bales  18 , different values are detected by the two sensors  66 . The output values of the sensors  66  are transmitted by the evaluation circuit  70  to a display device  72  that can be located, in particular, in the cabin of the tractor. For this purpose, in particular, a bus line  80  is used. The operator thus detects the shape of the bale  72  on the display device  72  with reference to two bar charts or some other representation and can countersteer if the bars are not the same size, in order to form a cylindrical bale. This task can also be taken over by an automatic system. For this purpose, refer to EP 1 813 146 A2, whose disclosure is incorporated into the present document through this reference. 
         [0028]    Furthermore, the signal of the sensors  66  can be used to detect an overload of the round baler  10 . If the output signal of the sensor  66  thus notes that a threshold is exceeded that corresponds to a maximum tension force in the pressing apparatus  64 , a warning note can be given to the operator via the display device  72  and/or automatically lower the pressure in the piston rod chamber of the hydraulic cylinder  54  and thus the tension in the pressing apparatus  64 . For this purpose, a proportional valve (not shown) can be controlled accordingly.