Abstract:
A round baler is provided with a bale-forming chamber and boundary apparatus of the bale-forming chamber that can be moved into an open position for ejecting a completed bale. The boundary apparatus includes a pivoting part rotatable between a first position, a second position and a third position. The axial dimensions of the bale-forming chamber can be changed by at least one side wall that can be moved by an adjustment drive. The adjustment drive is configured such that the axial dimensions of the bale-forming chamber increases when the pivoting part rotates to the second position and then reduces when the pivoting part rotates to the third position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Pursuant to 35 USC §119, this application claims the benefit of and priority to German patent application no. 102015210998.4, filed on Jun. 16, 2015, which is herein incorporated by reference in its entirety. 
     FIELD OF THE DISCLOSURE 
     The disclosure relates to a round baler and a boundary apparatus that can be moved into an open position for ejecting a completed bale. 
     BACKGROUND 
     Round balers are used to produce bales from stalk-shaped agricultural harvested produce. Such round balers have a bale-forming chamber and associated pressing means. After completion and optional wrapping of a bale with mesh, twine, or film, this bale is ejected toward the back out of the bale-forming chamber, after a rear door has been opened or a pivoting part holding a bale pressing element has been pivoted upward, in order to clear the path for the bale. 
     When leaving the bale-forming chamber, on one hand, the bale still has a not insignificant rotational energy from the bale-forming and optional wrapping process and, on the other hand, also gains kinetic energy while rolling out of the bale-forming chamber when it rolls down a rear-facing unloading ramp of the round baler. This kinetic energy can result in the bale rolling on the ground an undesired distance. In addition, it impacts the unloading ramp at a rather high speed, which could damage the wrapping material. The unloading ramp therefore is to be constructed with sufficient flexibility in the prior art in a rather complicated way in order to prevent this problem. 
     In the prior art (DE 103 39 652 A1), it has been proposed to attach a door to the rear side of the bale-forming chamber of the round baler, wherein this door can pivot about a vertical or approximately vertical pivoting axis and is used as a retaining device for the bale, in that it comes in contact with the end side of the ejected bale and brakes it. Such a door, however, also means additional costs and cannot influence the speed at which the bale reaches the unloading ramp, because the bale contacts the door only at a later time. 
     Furthermore, round balers have been described with side walls or side wall parts that move in the lateral direction, which are moved into an inner position during the forming of a bale and are moved outward for ejecting the bale, in order to reduce the friction forces of the bale during the ejection. Refer here to U.S. Pat. No. 4,334,467 A, DE 39 20 377 A1, DE 10 2005 036 181 A1, EP 1 264 531 A1, EP 1 364 574 A1, and EP 1 396 187 A2. When the bale is rolled out, the force exerted by the side walls on the bale is thus reduced by a relatively small value that does not lead to significant braking of the bale while it is rolling out and does not solve the mentioned problem. 
     According to DE 10 2007 012 174 A1, for the unloading process, the side wall is moved into a position in which a specified friction detected by sensors is produced. Here, greater costs for the controller are required, including an associated actuator for moving the side wall. The movement should guarantee an ejection of the bale, so that a significant braking effect also cannot be assumed here. 
     SUMMARY 
     The present disclosure provides a round baler in which the disadvantages mentioned above are not present or are present only to a reduced degree. 
     A round baler is equipped with a bale-forming chamber and boundary apparatus of the bale-forming chamber, which can be moved into an open position for ejecting a completed bale. The axial dimensions of the bale-forming chamber can be changed by at least one side wall that can be moved by means of an adjustment drive. The adjustment drive is configured such that the axial dimensions of the bale-forming chamber initially increase during the ejection of the bale relative to the dimensions provided for forming the bale and then (still during the ejection of the bale) are reduced again. 
     In this way, it is achieved that the clamping force of the side wall on the bale during the ejection is initially reduced relative to the clamping force while forming the bale and then is increased again. In this way, the bale can begin its rolling motion out of the bale-forming chamber at first without great braking, so that it does not remain stuck in the bale-forming chamber, and it is then braked by the side wall. Therefore, there is no longer the risk or there is a reduced risk of damage to the wrapping material while rolling down the unloading ramp, which makes it possible to shape the unloading ramp simpler than before. In addition, the bale no longer rolls too far away from the round baler. 
     The adjustment drive can be coupled with the boundary apparatus, i.e., can be controlled by this, so that the position of the side wall depends on the position of the boundary apparatus, which, in turn, specifies the position of the bale. It would also be conceivable, however, to control the adjustment drive directly as a function of the position of the bale detected by means of a sensor. 
     The coupling between the boundary apparatus and the adjustment drive can be realized in an arbitrary way, e.g., by a mechanical coupling, as described below, or by an electronic coupling between an actuator for moving the boundary apparatus on one side and an actuator for actuating the adjustment drive on the other side, analogous to DE 10 2007 012 174 A1. In this case, the actuator can control the adjustment drive such that the side wall assumes a position that is dependent on the position of the boundary apparatus or exerts on the bale a friction force that is dependent on this position and is detected by a sensor. 
     In particular, the boundary apparatus could include a pivoting part that carries means for forming a bale in the bale-forming chamber and can move rotatably between a bale-forming position and a bale ejection position. In a different embodiment, the boundary apparatus could also be constructed as a door (cf. U.S. Pat. No. 4,334,467 A1). 
     The pivoting part is preferably connected at a distance from its rotational axis to a control element that interacts with a double wedge-shaped control surface of the side wall. Multiple control elements and control surfaces could also be provided that are arranged at different distances from the rotational axis of the pivoting part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of the disclosure is described in more detail below and shown in the drawings. Shown are: 
         FIG. 1  a round baler according to the disclosure in a lateral view in a closed position and schematic representation, 
         FIG. 2  the round baler according to  FIG. 1  in a view from behind and in schematic representation, and 
         FIG. 3  an enlarged representation of the inner adjustment drive  32 . 
     
    
    
     DETAILED DESCRIPTION 
     A round baler  10  shown in  FIG. 1  includes a frame  12 , a chassis  14 , a tow bar  16 , a pick-up device  18 , rollers  20 , pressing elements  22 , a tensioning device  24 , side walls  26 , a bale-forming chamber  28 , pivoting parts  30 , and an adjustment drive  32 . 
     The round baler  10  is provided in the shown embodiment with a variable size bale-forming chamber  28 , but could also be provided with a constant size bale-forming chamber  28 . In the bale-forming chamber  28 , harvested produce picked up from the ground is formed into a so-called round bale that presses with its end sides on the side walls  26 . 
     The frame  12  is especially easy to see in  FIG. 2  and represents a welded and/or threaded assembly on which all of the components of the round baler  10  are mounted. The frame is supported on the chassis  14  and can be connected with the tow bar  16  to a tractor, not-shown. The frame  12  carries, among other things, cover parts, not-shown, some of the rollers  20 , the side walls  26 , and the pivoting parts  30 . The frame  12  amply surrounds the area enclosed by the side walls  26  and the pressing elements  22 . 
     The chassis  14  consists of an axle and wheels, in a way that is not described in more detail, on which the frame  12  contacts. The tow bar  16  attaches to the front side of the frame  12  in a rigid or height-adjustable way. The pick-up device  18  is typically constructed as a so-called pick-up and is attached to the frame  12  in a height-adjustable way. The pick-up device  18  can also be arranged downstream of a known cutting device. The pick-up device  18  picks up produce on the ground and forwards it via an optionally provided cutting device into the bale-forming chamber  28 , where it is shaped into a cylindrical round bale. 
     Some of the rollers  20  are supported so that they can rotate fixed in place in the frame  12  and are designated with  20 ′, one of the other rollers  20  can be moved against the force of a spring that is not described in more detail so that the pressing elements  22  can yield to the increasing bale diameter, and is designated with  20 ″; each of the other rollers  20  can be pivoted above a pivoting axis  34  on pivoting parts  30 . These rollers  20  are designated with  20 ″′ and have wide constructions, run parallel to each other, and are arranged such that the pressing elements  22  can run over these rollers and enclose the bale-forming chamber  28 . In addition to the rollers  20  there are also cylinders  36  that are located above an inlet opening  38  into the bale-forming chamber  28 , which operate as so-called starter rollers at the beginning of the bale formation, and on which a part of the weight of the round bale can be supported. 
     The pressing elements  22  are constructed as belts that run parallel to each other and essentially cover the bale-forming chamber  28  over its width. Instead of the construction as a belt, a construction as a belt-and-slat conveyor or as a wide belt could also be selected, as is also known; in this case, only one pressing element would be present, which, however, shall also be included within the scope of protection. The pressing elements  22  are endless and are therefore set into revolving motion such that they form a friction-fit contact on at least one drivable roller  20 . The pressing elements  22  form, in the area of the inlet opening  38 , a bridge that is formed into an inward expanding loop with increasing amount of harvested produce and surrounds the round bale. The pressing elements  22  are therefore held under tension such that they are guided over the position-changing roller  20 ′. 
     The tensioning device  24  is formed in a known way such that the roller  20 ″ is guided on a not-shown arm, sled, or the like against the force of the spring and always keeps a loop of the pressing elements  22  in tension. 
     The side walls  26  essentially assume the shape of a “D” in a view of  FIG. 1 , wherein the rear end area at the right in  FIG. 1  forms an arc that essentially follows the circumferential line of the completed round bale, i.e., on a part of a circular arc. The side walls  26  basically have a one-piece construction, i.e., they are divided not like in conventional round balers along an approximately central vertical plane, but instead they can be formed from multiple parts. From  FIG. 2  it emerges that the side walls  26  assume a not insignificant distance to the frame  12  and thus can be deflected outward, as is described below. The side walls  26  have a construction that is resistant to bending by means of reinforcing braces  40 , wherein the reinforcing braces  40  can be screwed on or welded on. According to the illustration in  FIG. 2 , the reinforcing braces  40  have an approximately star-shaped profile with respect to the pivoting axis  34  and run tangentially past this axis at a slight distance, in order to ultimately meet each other at more or less of a right angle. Due to this profile, they enclose a chamber  42  that is rectangular in this embodiment. In its front end area, the side walls  26  are connected essentially rigidly to the frame  12 ; however, a slight pivoting motion starting from a position according to  FIG. 2  by a few degrees outward is possible such that either the side walls  26  are formed in the connection area, e.g., are made from a flexible plate or are fixed in a flexible connection, e.g., to a flexible flange or spring-loaded screws. The connection of the side walls  26  on the frame  12  takes place essentially along a more or less vertical line on the front end of the bale-forming chamber  28 . In the area of the pivoting axis  34 , each side wall  26  is guided on an axle  44  that is rigidly attached to the frame  12  and simultaneously acts as the pivoting axis for the pivoting parts  30 . 
     The bale-forming chamber  28  is variable in its size and is bounded at the beginning, i.e., for an empty bale-forming chamber  28 , by an approximately triangular, cylindrical space between the pick-up device  18  and the pressing apparatus  22  and laterally by the side walls  26 . With the increased feeding of harvested produce, the bale-forming chamber  28  is expanded and ultimately assumes a cross section that follows the shape of the side walls  26  in the rear area. 
     The pivoting parts  30  are provided in this embodiment on each side with one or more arms  46  running radial to the pivoting axis  34  and one or more crossbeams  48  that are attached on its/their radially outer end and run perpendicular thereto. On the end of each crossbeam  48 , there is a roller  20 ″′. The pivoting parts  30  are arranged on the axle  44  so that they can pivot with the radially inner end of each arm  46 . The position of the arms  46  is controlled by means of a drive  50  that contains a motor  52 , and for each pivoting part  30 , a traction gear  54  or another kind of pivoting drive. The motor  52  can be braked in each of its positions and hold the arms  46  fixed in place accordingly. Driven wheels  56  allocated to each of the traction gears  54  are supported concentric to each other and to the axle  44  and are each connected locked in rotation with a pivoting part  30 . The control of the pivoting parts  30  is realized such that the front pivoting part  30  is moved during the bale-forming phase in order to help with the formation of a bale core, and the rear pivoting part  30  assumes a lower position while the round bale is formed and an upper position when it is ejected. The rear pivoting part  30  is thus used as boundary apparatus of the bale-forming chamber  28  that can be moved into an open position for ejecting a completed bale. The lower end position of the rear pivoting part  30  is shown in  FIG. 1 , while it is pivoted upward by approximately 180° into its upper end position. It is noted that the front pivoting part  30  is not absolutely required or could be connected rigidly to the rear pivoting part  30 . 
     The adjustment drive  32  contains a control surface  58  that rises and then falls again (i.e., double-wedge-shaped) and a control element  60  (cf.  FIG. 3 ) and is used for and during the ejection of the round bale to initially lower the pressure and thus the friction of the side walls  26  on its end faces, so that the round bale can be unloaded more easily out of the bale-forming chamber  28 , and then can be increased again in order to brake it. 
     The control surface  58  is positioned on a circular arc running concentric to the pivoting axis  34  and is mounted on the outer side of both side walls  26 , if it were also sufficient to provide only one rising surface, i.e., on one side wall  26 . In the present embodiment, the control surface  58  is formed from a bent, steel double wedge that is screwed onto the side walls  26  falling and rising equally within the chamber  42 . 
     An additional control surface  58 ′ is located farther outside on a larger circular arc and mounted on the outside of both side walls  26 , if it were also sufficient to provide only one rising surface, i.e., on one side wall  26 . In the present embodiment, the additional control surface  58 ′ is formed from a bent steel double wedge that is screwed onto the side walls  26  falling and rising equally within the chamber  42 . 
     The control element  60  interacting with the control surface  58  is provided on the side of the arm  46  of the rear pivoting part  30  toward the longitudinal center plane of the round baler  10  and constructed as a sliding surface. For minimizing the friction, the friction surfaces are lubricated; alternatively, the control element  60  could also be constructed as a wheel, roller, ball, or similar rotating element. The control element  60  is arranged such that it describes a round circular path for rotation of the pivoting part  30  about the pivoting axis  34  and moves on the control surface  58 . Preferably, the control element is always in contact on the control surface  58 . 
     A control element  60 ′ interacting with the additional control surface  58 ′ is provided on the side of the arm  46  of the rear pivoting part  30  toward the longitudinal center plane of the round baler  10  in the vicinity of its radially outer end and is constructed as a sliding surface. For minimizing the friction, the friction surfaces are lubricated; alternatively, the control element  60  could also be constructed as a wheel, roller, ball, or similar rotating element. The additional control element  60  is arranged such that it describes a round circular path for rotation of the pivoting part  30  about the pivoting axis  34  and moves on the additional control surface  58 ′. Preferably, the control element  60  is always in contact on the additional control surface  58 ′. 
     The control elements  60 ,  60 ′ lie on the highest elevation of the control surfaces  58 ,  58 ′, if the rear pivoting parts  30  are located in their lower end position—cf.  FIG. 1 —and the round bale can be formed. If the pivoting parts  30  are moved into their center position, in which the round bale begins its movement out of the bale-forming chamber  28 , the control element  60 ,  60 ′ moves to the lowest position of the control surfaces  58 ,  58 ′. If the pivoting parts  30  are moved into their upper position, in which the round bale continues its movement out of the bale-forming chamber  28  and exits the bale-forming chamber  28 , the control elements  60 ,  60 ′ are moved toward a higher position of the rising control surfaces  58 ,  58 ′, whose height agrees with the lower pivoting position or can be somewhat lower or even higher, in order to brake the bale, because it reaches an unloading ramp  62 . 
     As soon as a round bale is formed in the bale-forming chamber  28 , the rear pivoting part  30  is raised, whereupon the side walls  26  move outward due to the pressure in the bale-forming chamber  28  from the pressed harvested produce. Consequently, the friction is reduced between the inner side of the side walls  26  and the end faces of the round bale and the bale begins to roll out from the bale-forming chamber  28  due to the force of gravity in the direction toward the unloading ramp  62 . Shortly afterward, the side walls  26  are brought back together again and the bale is braked, before this reaches the unloading ramp  62 . As soon as the round bale has completely exited the bale-forming chamber  28  and the round baler  10  has been moved farther such that the rear pivoting part  30  can be lowered again, a pivoting movement of the rear pivoting part  30  is realized in the opposite direction, so that the control element  60 ′,  60 ′ is moved toward the smallest and ultimately toward the largest elevation of the rising surfaces  58 ,  58 , and in this way presses the side walls  26  outward and then inward and a new bale can be formed.