Abstract:
A large round baler comprises a baling chamber and a door that is arranged in the rear area of the baling chamber and includes a pair of wings mounted to opposite sides of the baler so that each is displaceable about an upright pivot axis between a closed position, in which the wings extend inwardly along the rear of the baling chamber, and an open position, in which a passage is defined through which a finished bale can pass after being ejected from the baling chamber. The baler may be of a type including a carrier for bale-forming devices that can be displaced in the baling chamber, independently from the door, between a bale-forming position and a bale ejection position, and that the door, when closed, blocks direct access to the carrier and the devices for forming the bale.

Description:
FIELD OF THE INVENTION 
   The invention relates to a round baler comprising a baling chamber and a door that is arranged in the rear area of the baling chamber and is displaceable about a pivot between a closed position, in which the door extends along the rear of the baling chamber, and an open position, in which a finished bale can be ejected from the baling chamber. 
   BACKGROUND OF THE INVENTION 
   Round balers are used to turn agricultural harvested crops into bales. Such round balers comprise a baling chamber and corresponding pressing devices. Upon completion of a bale, in conventional round balers a rear door swivels upward to eject the bale. 
   In order to achieve that the bale reaches the door from the swivel area so that the door can be closed again as quickly as possible, so-called discharge devices are known, which move the bale away from the pivot area of the door. It has been suggested (DE 43 15 374 C) to equip such a discharge device with a hold-back device, which prevents the bale from rolling too far away from the round baler, for example, down a hill. These devices are additional elements, which increase the weight of the round baler and make its manufacture more complex and expensive. 
   Other designs of round balers have been suggested (EP 1 308 078 A), comprising a carrier that fastens elements, which support the belt-shaped pressing device in the lower region of the baling chamber of the round baler. The carrier can pivot between said bale-forming position and a bale ejection position, in which it is swiveled backward and upward and releases an opening on the rear of the baling press. On such round balers, movable elements, for example the pressing devices, can be found in the rear area during operation. From an occupational safety aspect these round balers are therefore questionable. 
   The subsequently published document DE 102 50 425 A suggests to install a rear guard in form of a shield or similar mobile fittings on such a round baler. 
   The problem on which the invention is based is to provide a round baler, which does not exhibit the above-described disadvantages or to a lesser degree. 
   SUMMARY OF THE INVENTION 
   According to the present invention, there is provided an improved discharge door arrangement for a large round baler. 
   An object of the invention is to provide a large round baler having a discharge door which pivots about an upright axis when moving between a closed position during bale formation and an open position for bale discharge. 
   It is suggested to install a door on the rear of the baling chamber of the round baler, wherein said door can swivel about a vertical or substantially vertical pivot. The door is not dependent on the pressing devices of the baling chamber since the latter are generally swiveled upward to release the baling chamber to the rear for ejection of a bale. Due to the vertical arrangement of the pivot the door can be opened and closed without great efforts and hence without large and expensive drives. 
   Alternatively or in addition it is suggested to equip the baling press with a carrier, which carries devices for bale-forming purposes in the baling chamber and which is displaceable between a bale-forming position and a bale ejection position, and to design the door such that it can be moved independently from the carrier. In a baling press, in which the bale-forming devices that move during operation would otherwise be exposed openly to the rear, this way a rear guard is achieved to improve occupational safety. 
   Since the door can move independently from the carrier, it can be displaced in any random direction and can in particular swivel about a vertical axis. 
   In a preferred embodiment the door serves as a retention device for the bale. It comes into contact with the ejected bale at its front and slows it down. This way it can be prevented that the bale moves too far away from the round baler. In order to prevent undesirable wear of the door, it is conceivable to equip the end region of the door resting against the bale with rotational elements, which can move freely or can be slowed down. 
   As a rule the door comprises two leaves, between which the bale is ejected. It can therefore be slowed down on both sides, avoiding undesirable rotational movements of the bale about the vertical axis. Embodiments with only a single door however are conceivable as well. 
   The door is preferably pre-stressed in the closed position, which can occur by means of weights and/or springs. This also leads to a defined lateral force on the ejected bale, which suffices to slow it down safely. It may however also be advisable to move the door additionally or exclusively by means of a power (hydraulic, pneumatic or electric) drive. In a preferred embodiment the power drive moves the door into an intermediate position between the closed and open positions. From said position it can be opened further—for example by the discharged bale—against the pre-stress. To this end it is possible to provide a coupling between the drive and the door, which allows a free relative movement between the drive and the door over a specific angle range of the door movement. 
   The power drive can be synchronized with the movement of the carrier in order to achieve a useful time progression of the movements. Another benefit of such a drive consists of the fact that it is possible to rotate the two wings of a door at different angles. This allows also the bale to be rotated in a specific, desired direction, for example in order to prevent it from rolling down a hill. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawing shows an exemplary embodiment of the invention, which is described in more detail in the following. It shows: 
       FIG. 1  is a schematic left side view of a large round baler, constructed in accordance with the principles of the present invention, shown in a slightly filled operating state. 
       FIG. 2  is a view of the round baler from  FIG. 1  shown in a filled state. 
       FIG. 3  is a view of the round baler from  FIG. 1  shown during the discharge operation. 
       FIG. 4  is a top view of the round baler shown during formation of a bale. 
       FIG. 5  is a top view of the round baler shown after discharge of a bale. 
       FIG. 6  is a top view of a swiveling device of the door shown in a closed position. 
       FIG. 7  is a side view of the door swiveling device. 
       FIG. 8  is a top view of the swiveling device of the door shown in an open position. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows one embodiment of a round baler  10  comprising a frame  14 , which is supported on the ground by a wheel assembly  18 . On the front of the frame  14 , a tow bar  16  is arranged in order to attach the round baler  10  to a tractor used for towing the baler  10  across a field. A crop receiving device  20  in form of a pick-up device serves to pick up harvested crop from the ground, e.g., a windrow of hay or straw. The harvested crop that is picked up by the receiving device  20  is fed to the entrance of a baling chamber  12  and rolled there in a spiral shape into a cylindrical bale  36 , is tied up and subsequently placed on the ground. 
   A lower, stationary roller  60  and two upper rollers  62 ,  64  delimit an crop inlet or  40  of the baling chamber  12 . The baling chamber  12  is furthermore formed by an endless bale-forming device  34  defined by a belt arrangement, which is guided around a number of fixed rotary elements  24   a–d  and movable rotary elements  32   a–f . Thus, the periphery of the baling chamber  12  is essentially surrounded by the bale-forming device  34 , it is closed off laterally by side walls  38 . 
   Four of the rotary elements  32   a ,  32   b ,  32   c  and  32   d  can each pivot freely in pairs at the end of a delta- or triangular-shaped carrier  26 , having opposite sides which each comprise a first leg  42  and a second leg  44 , which are connected to each other by means of a strut  46 . The first and the second legs  42  and  44  of each side of the carrier  26  join in a bearing  48 , which is seated on a bearing part  50  on the outside of a respective one of the side walls  38 . The bearing part  50  is located directly in or close to the center of the baling chamber  12  and/or the side wall  38 . 
   Adjustment of the carrier  26  occurs by means of a not depicted actuator, e.g. a hydraulic cylinder, a rotating hydraulic motor with a gear or an electric or pneumatic motor. The carrier  26  can swivel between two end positions, namely a lower position, as shown in  FIG. 1 , in which the rotary elements  32   a  through  32   d  are located substantially close to a horizontal plane beneath the baling chamber  12 , and a position that is offset upwardly by nearly 180 degrees thereto, as shown in  FIG. 3 , in which the rotary elements  32   c ,  32   d  of the second leg  44  rest between the intermediate and the rear fixed rotary elements  24   d  and  24   c.    
   A tensioning mechanism  28 , for the purpose of tightening the endless belts of the bale-forming device  34 , comprises a tensioning arm  52  mounted, as by respective bearings  54 , at each side wall  38  of the baling chamber  12  for swinging vertically. A rotary element  32   e  is mounted on a radially outer end of each arm  52  and its counterclockwise movement about the axis of the bearing  54  is resisted by a tensioning element, which is not shown. The bearings  54  of the tensioning arms  52  are respectively located in the areas of the side walls  38  above and in front of the bearing parts  50  and below the plane about which the fixed upper rotary elements  24   a–d  are arranged. The tensioning element is designed in the usual fashion as a mechanical spring or as a hydraulic motor, which can be displaced against a possibly modifiable resistance. Such a resistance can be produced by means of a preferably adjustable throttle in a hydraulic circuit, as is known in general. The degree of resistance at the same time determines the density and the maximum weight of the bale  36 . 
   The rollers  62 ,  64 , bordering the upper side of the inlet  40 , and the rotary element  32   f  are attached to a swiveling carrier  30 , which comprises a frame  56  that can swivel vertically in its central region about a pivot  58 . The rotary element  32   f  and the rollers  62 ,  64  can pivot freely in the frame  56 , wherein the roller  62  runs coaxially to the pivot  58 . The frame  56  can be pre-stressed to a specific position by means of a tensioning element. 
   The bale-forming device  34 , among other things, runs across the fixed rotary elements  24   a–d  and across the movable rotary elements  32   a–f  and is placed against at least one rotatably driven fixed rotary element  24   a–d  by means of the tensioning mechanism  28  such that it can be caught safely. The bale-forming device  34  assumes a starting position, in which it bridges the entrance  40  in a barely stretched manner, and an end position, in which it wraps around the bale  36  like a large loop. The baling chamber  12  therefore has a variable size, i.e., its diameter increases with the size of the bale  36 . During its production, the bale  36  is located in the baling chamber  12  and largely wrapped by the bale-forming device  34 , but it drops out of the baling chamber  12 , i.e. the chamber between the side walls  38 , onto the ground as soon as the carrier  26  with the movable rotary elements  32  swivels upward counter-clockwise, looking at the drawing. 
   The side walls  38  could be mounted for being displaced transversely to the driving direction so that upon ejection of the bale  36  they reduce the contact pressure between opposite ends of the bale and inner surfaces of the side walls  36 , allowing the bale  36  to exit more easily and hence more quickly. It would, for example, suffice if the side walls  38  were able to move apart a few centimeters from each other. The side walls  38 , while shown fixed in this application, could be designed for moving with the carriers  26 . 
   The function of the round baler  10  is as follows: As long as the round baler  10  is not fed any harvested crop and the baling chamber  12  is empty, the carrier  26  is located in its lower, front end position, in which the first, front rotary element  32   a , which is carried by the lower end of the first leg  42 , is disposed close to the roller  60  and the rotary elements  32   a – 32   d  are located close to a substantially horizontal plane. The tensioning arm  52  will, at that point, be pushed to the rear, while the pivoting carrier  30  assumes its farthest possible counter-clockwise end position. A section of the bale-forming device  34  extends across the insides of the rollers  60  and  64  and closes the entrance  40 . This state is shown in  FIG. 1 . 
   As soon as harvested crop is conveyed into the baling chamber  12  via the receiving device  20 , it will lead to an excursion of the section of the bale-forming device  34  towards the inside of the baling chamber  12 , causing the tensioning arm  52  to begin its forward movement in order to shorten loops  66 ,  68  formed by the bale-forming device  34  in the upper region of the round baler  10 . As the bale  36  grows in diameter, the tension in the bale-forming device  34  will act against the rotary element  32   f  and will cause the carrier  30  to pivot counterclockwise about the pivot axis  58 . This moves the roller  64  to the rear so as to force the bale  36  away from the entrance  40  so that the arriving harvested crop can be easily received. While the bale diameter increases, the carrier  26  remains in its position illustrated in  FIGS. 1 and 2 . 
   When the bale  36  has reached its largest diameter (see  FIG. 3 ), the swiveling carrier  30  will have reached its maximum counter-clockwise position and the tensioning arm  52  will have assumed its front position, in which the first loop  66  has its shortest length (see  FIG. 2 ). Although shown slightly separated from them, the bale  36  rests on the front of the roller  60  and the adjoining first rotary element  32   a . However, the tension in the bale-forming device  34  does keep the bale  36  from coming into contact with the first and the second rotary elements  32   c ,  32   d  and the belt sections running across them. If needed, another, not depicted roller can be provided between the two second legs  44  for providing support for the bale  36 . When the bale  36  has reached its maximum size, the radial offset of the first and second rotary elements  32   a  and  32   b  on the first leg  42  prevents the adjacent sections of the bale-forming device  34  from resting against each other. In this state, the bale  36  can be tied or wrapped with a film or net so that it does not fall apart when leaving the baling chamber  12 . 
   After the bale  36  has been completed, it can be ejected from the baling chamber  12 , for which purpose the carrier  26  is swiveled back and upward counter-clockwise. Especially due to the carrier  26  being pivotally coupled to location in or close to the center of the side walls  38 , the bale  36  will drop to the ground after only a short swivel path of the carrier  26  of, for example, about 90 degrees. After the carrier  26  pivots counterclockwise about 180 degrees, the first rotary element  32   a  is located on the first leg  42  so far above the ground that the round baler  10  can travel further forward without hitting the bale  36 . 
   As soon as the bale  36  has rolled out of the baling chamber  12 , the carrier  26  is swiveled again downward into the position shown in  FIG. 1 . This tensions the bale-forming device  34  again, and the tensioning arm  52  is moved again to the back. 
   The illustrated embodiment of the baler is disclosed in detail in EP 1 308 078 A. Other possible embodiments are described in DE 198 51 470 A, DE 102 41 215 A and EP 1 264 531 A. The disclosed content of these documents is included by means of reference in the present invention. 
   Based on  FIGS. 1 through 3  it is evident that the round baler  10  is open to the back so that the finished bale  36  can be ejected. The bale-forming devices  34 , which move during operation, are hence freely accessible in the rear area of the round baler  10 , which is not beneficial from an occupational safety aspect. In order to improve the latter, a door  70  is arranged on the rear of the round baler  10 . The door  70 , as is illustrated in  FIGS. 4 and 5 , comprises two wings  72 , which are composed of pipes. Respectively associated with the two wings  72  are two swiveling devices  74  respectively mounted to upper rear locations at opposite sides of the baler  10 . Each of the wings  72  extends, in its closed position, initially downward from an associated one of the two swiveling devices  74 , then to the back and inside, then again downward and finally forward up to a lower swiveling device  76 . The wings  72  at each side of the baler  10  are linked to the upper and lower swiveling devices  74  and  76 , respectively, so as to be able to pivot about a vertical, pivot axis  78 . This is accomplished through bearing arrangements  96 , which are arranged between arms  98  connected to the round baler  10  and the wings  72 . The lower swiveling devices  76  are simple bearing arrangements, which correspond to the bearing arrangements  96  in their design and function. 
   When forming the bale  36 , the doors  70  are located in the closed position, as illustrated in  FIG. 4 . When the bale  36  is discharged, the doors  70  transition into the open position, as is illustrated in  FIG. 5 , in which the wings  72  are swiveled outward. During ejection of the bale  36 , elements  80  in the form of cylinders mounted for turning freely, or in a slowed-down fashion, on vertically extending sections of the wings  72 , initially rest against the front of the bale  36   
   The door  70 , on one hand, provides a shield to the carrier  26  and the bale-forming device  34  during production of the bale  36 , on the other hand it has a braking effect during ejection of the bale  36 . It therefore serves as a retention device, which prevents the bale  36  from rolling too far away from the round baler  10  or even for example down a hill. The shielding effect of the doors moreover eliminates the necessity to swivel the carrier  26  relatively slowly for occupational safety reasons. To improve the shielding effect of the door  70 , the wings  72  could be supplemented with sheets, fabrics or the like. The wings  72  can consist of metal or non-metallic material. Instead of round pipes, as is shown in the drawings, cornered pipes, plates and/or sheets can be used as well. 
   The  FIGS. 6 through 8  show detailed views of the swiveling device  74 . Each figure shows the upper swiveling device  74  illustrated in  FIGS. 4 and 5  (the right one in the driving direction of the round baler  10 ), which has assumed the closed position in  FIG. 6  and the open position in  FIGS. 7 and 8 . Based on these figures, it is evident that the wings  72  on the upper swiveling device  74  are each attached to a swiveling plate  84  with a flange  82  and screw bolts. The swiveling plate  84  and the flange  82  can rotate jointly with the leaf  72  about the pivot axis  78 . To the swiveling plate  84 , a pin  94  is connected in an arcuate opening  92  formed at a radius about the axis  78 , wherein the pin  94  is connected to a first end of a drive  86  in form of a double-action hydraulic cylinder. The drive  86  is linked to the side wall  38  with its other end. Additionally, a spring  88  extends between the flange  82  and the side wall  38 . Moreover a gas spring  90  is connected between the swiveling plate  84  and the side wall  38 . The spring  88  pre-stresses the leaf  72  in the closed position. The gas spring  90  ensures a vibration dampening effect. The drives  86  enable an active opening and closing of the door  70 . Since the drive  86  is coupled via the pin  94  and the arcuate opening  92  to the swiveling plate  84 , undesirable damage to the leaf  72  is prevented in case a bale  36  should still be located between the wings  72  when closing the door  70 . It should be noted that the wings  72  are supported on the arms  98  by the bearing arrangements  96 , see  FIG. 1 . 
   The drives  86  are actuated by an electro-hydraulic control device  99 . The latter also controls the movement of the carrier  26  so that the control unit can initiate the movements of the door  70  and the carrier  26  in a time-coordinated sequence. After swiveling the carrier  26  upward, the door  70  is brought by means of the drives  86  into a slightly open position (generally as soon as it is located roughly in the middle between the bale-forming position and the bale ejection position), in which it is located roughly in the middle between the positions illustrated in  FIGS. 4 and 5 . The ejected bale  36  moves the wings  72  outward against the force of the springs  88 , wherein the pin  94  moves in relation to the arcuate opening  92  since the drive  86  then remains stationary. The bale  36  is then slowed down by the wings  72  and comes to a halt. Thereafter the control device  99  returns the carrier  26  into the bale-forming position. Independent hereof the drive  86  can be retracted again as soon as (for example based on a time period that has passed or based on the signal of a suitable sensor) it can be assumed that the bale  36  has come to a halt. Shortly before reaching the closed position, the movement of the door  70  is preferably slowed down in order to reduce the risk of an accident. 
   The braking effect of the door  70  on the bale  36  has the advantage that an undesirable rolling away of the bale  36  is prevented. This is useful in particular on a hill. In this case, it may be useful to bring the bale  36  into an angled position in relation to the driving direction of the round baler  10  so that it is aligned transversely to the direction of the hill gradient and cannot roll down the hill. For this purpose the drives  86  can bring the wings  72  of the door  70  into respectively different positions. The control device  99  is hence equipped to actuate the two drives  86  differently. Moreover it is connected to an inclination sensor  100  in form of a pendulum or the like in order to be able to actuate the drives  86  in a suitable fashion. Information about the hill incline can also be deduced from the signals of a satellite antenna of a position determination system of the tractor. 
   Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.