Abstract:
Provided is a combination of a tractor and a implement drawn by the tractor by way of a draw bar, supported on the ground by wheels, the implement having a processing element interacting with a field. A controller is connected to a first actuator disposed for adjusting the angle between the draw bar and the implement, and to a second actuator disposed for adjusting the angle of the wheels of the implement about the vertical axis. The controller can be operated for actuating the two actuators in such a manner that the longitudinal axis of the processing element is always oriented at least nearly orthogonal to a target line.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The disclosure concerns a combination of a tractor and a implement that is drawn by the tractor by way of a draw bar, and supported on the ground by wheels and that comprises a processing element interacting with a field, with a control device that is connected to an actuator, with which the implement can be steered in a lateral direction relative to the tractor. 
       BACKGROUND OF THE DISCLOSURE 
       [0002]    In agricultural applications, there are frequently cases in which pulled implements are drawn behind tractors and the intention is to move the implements on a desired theoretical path, so as to, for example, remove harvested crops from a field or bring out materials onto a field. In the past, to this end, the tractor was steered and the implement suspended by way of a draw bar on a coupling of the tractor followed the tractor, wherein the theoretical path of the implement could not always be maintained exactly because of the different movement paths of the tractor and the implement. 
         [0003]    In order to simplify in a baler, the preparation of a bale uniform over the width of the bale formation chamber, the proposal in U.S. Pat. No. 4,433,533, regarded as generic, was to detect the size of the bale over the width of the round bale, and as a function of the individual form of the bale, either to move the baler in a lateral direction relative to the tractor by way of a hydraulic cylinder or to swivel the wheels of the baler around the vertical axis. In this way, the tractor is moved along the windrow by the operator, while the baler automatically moves on a curve-like or meandering path and a cylindrical bale is produced. 
         [0004]    Furthermore, EP 1 634 491 A1 describes a baler with sensors for the detection of the bale size and distributed over the width of the bale-forming chamber. The sensors are connected to the control, which controls an automatic steering direction of the tractor in such a manner that the tractor is conducted automatically along the windrow and, dependent on the individual shape of the bale, moves more or less far laterally next to the windrow so as to produce a cylindrical bale. 
         [0005]    EP 1 685 759 A1 describes another baler in which the tractor is conducted automatically along the windrow and sensors distributed over the width of the bale-forming chamber for the detection of the bale size are connected to a control, which controls the automatic steering direction of the tractor, or an actuator, which adjusts the draw bar of the baler so as to produce bales that are homogeneous over the width. 
         [0006]    The known embodiments in which the tractor is steered so as to make it possible for the implement to be moved along the desired theoretical path have the disadvantage that the driver of the tractor is also exposed to the lateral movements, which over time can be tiring and uncomfortable. Moreover, there is the danger with a baler, for example, that the wheels of the tractor move over the draw bar and compress and soil it in an undesired manner. With embodiments in which the implement is forced-steered relative to the tractor, there are occasionally, on the other hand, operating situations in which a processing element of the implement—for example, with a baler or a trailer, a crop collector—is not oriented in an orthogonal manner relative to the windrow, that is, it is moved in a lateral direction relative to the windrow, which can lead to undesired distortions and wear phenomena in the tines of the crop collector. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    The goal of the disclosure is to be found in making available a combination of a tractor and a drawn implement, in which a lateral movement of the processing element of the implement relative to a theoretical line will not be expected or will occur to a reduced extent. 
         [0008]    A combination is composed of a tractor and a implement drawn by a tractor. The implement is drawn by a tractor by way of a draw bar; it is supported on the ground by wheels and comprises a processing element that interacts with a field, for example, a crop collector or a sprayer boom. Furthermore, a control device is connected, which is found on board the tractor or the implement or can be adjusted spatially over both. The control device is connected to a first actuator, which is used to adjust the angle between the draw bar and the implement. The first actuator can (for the direct adjustment of the draw bar relative to the implement) be located between the draw bar and a carriage of the implement or (for the indirect adjustment of the draw bar relative to the implement) between the tractor and the draw bar. Furthermore, the control device is coupled to a second actuator, which is used to steer the wheels—that is, to adjust their angle around the vertical axis. During operation, the control device controls the two actuators in a way so that the longitudinal axis of the processing element is always oriented at least approximately orthogonal to a theoretical line. 
         [0009]    In this way, it is possible for the processing element to always be oriented transverse to the theoretical line, which reduces the wear with a processing element interacting with a windrow. 
         [0010]    With a preferred embodiment of the disclosure, the implement is a collecting vehicle for the crops, for example, a baler for rectangular or round bales or a trailer. As a processing element, a crop collector is provided, which is used to take up a windrow from the ground. The collecting vehicle also has a container to hold the collected crops, in particular, in the form of a baling chamber or a loading container. In order to obtain a uniform distribution of the crop in the container and thus uniform bales, sensors are distributed over the width of the container; they detect the lateral distribution of the crop. The sensors are connected to the control device. The signals of the sensors serve the control device (in addition to the orientation of the processing element transverse to the theoretical line, which corresponds to the longitudinal axis of the windrow in this embodiment) as a second parameter to control the actuators. The container is correspondingly filled up according to a filling strategy. 
         [0011]    The control device can be acted on by a position determining device and/or a detection device with information regarding the location of the theoretical line. 
         [0012]    The tractor can be conducted along the theoretical line by an operator or based on signals of a position-determining device and/or the detection device (particularly those mentioned previously). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Embodiments of the disclosure are described in detail below with reference to the accompanying drawings wherein: 
           [0014]      FIG. 1  is a side view of a tractor with a drawn implement; 
           [0015]      FIG. 2  is a top view of the tractor and the implement; and 
           [0016]      FIG. 3  is a flow chart according to which the control device of the implement works. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]      FIG. 1  shows a side view of an agricultural tractor  10  in the form of a tractor and a implement  12 , coupled by way of a draw bar  14  to a suspension coupling  28  of the tractor  10 , in the form of a round baler with a variable size baling chamber. The tractor  10  is built on a frame  18 , which is supported on steerable front wheels  20  and drivable rear wheels  22  and carries a cab in which there is a work station for the operator  26 . 
         [0018]    The implement  12  comprises a carriage  32  that is supported on the ground via steerable wheels  34 , a processing element  36  in the form of a crop collector  38  to collect crops lying on the ground in a windrow  40 , and a conveyer  42  that conveys the crops taken up by the crop collector  38  into a container  46  in the form of a baling chamber  44 . The baling chamber  44  is limited in a manner that is in fact known by baling elements (not depicted) in the form of belts. A completed bale can be ejected through a back door that can pivot upwards, and deposited on the field. The mechanical drive of the driven elements of the implement  12  is carried out by the tractor  10  via a universal joint shaft  30 , although a drive with electric motors would also be conceivable, which are supplied with electrical energy by the tractor  10 . 
         [0019]    In total, three sensors  50  are distributed over the width of the container  46 ; they are used to detect the diameter of the bale and/or to detect the tension of the baling elements, which likewise contain information on the distribution of the crops over the width of the container  46 . The sensors  50  are connected to a control device  52 , which is located on board the implement  12 , but which could also be located on board the tractor  10 . The control device  52  is connected via a valve arrangement  56  to a first actuator  54  in the form of a hydraulic cylinder, which is articulated on one end on the draw bar  14  and on the other end on the carriage  32 . The control device is connected, moreover, via the valve arrangement  56  to a second actuator  58  in the form of a hydraulic cylinder, which is coupled to a rod  60  to swivel the wheels  34  of the implement  12  around the vertical axis. By way of feedback sensors  70 ,  72 , the control implement  52  gives information regarding the actual angles of the draw bar  14  and the wheels  34 . 
         [0020]    A detection device  62  in the form of a camera is placed on the front side of the tractor  10 ; it detects the windrow  40  optically and is connected to an image processing system, which emits a steering signal to a steering control  64  of the tractor, which in turn adjusts the steerable front wheels  20  of the tractor via a suitable actuator (not depicted) in such a manner that the longitudinal middle axis of the tractor  10  is conducted at least approximately on a theoretical line  66 , which corresponds to the longitudinal axis of the windrow  40 . In another embodiment, data regarding the position of the windrow are stored in the steering control  64  and a position-determining device  68  (for example, in the form of a GPS antenna) transmits to the steering control  64  up-to-date position information, which is used together with the stored data regarding the position of the windrow by the steering control  64  to control the actuator for the steerable front wheels  20 . Both variants mentioned in this paragraph can also be combined (see EP 1 266 553 A2). The steering control  64  continuously transmits to the control device  52  data regarding the lateral position of the theoretical line  66  relative to the longitudinal middle axis of the tractor  10  and the corresponding time of the detection and/or the corresponding position in the forward direction, and is, to this end, connected to the control device  52  via a bus. 
         [0021]    In the light of the foregoing, the mode of operation of the control device  52  shown in  FIG. 3  is produced. After the start in step  100 , step  102  follows, in which the expected position of the theoretical line  66  relative to the middle line of the implement  12  after traversing a stretch of the length x (of, for example, 1 m) is determined on the processing element  36 . Thus, the expected lateral offset of the windrow  40  relative to the longitudinal middle plane of the implement  12  is determined on a site lying approximately the distance x in front of the implement  12 . This position can be determined with the aid of the signals by the steering control  64  and the distance traversed until the attaining of the elapsed time or the distance traversed from the implement  12  (between the detection by the detection device  62  and the reaching of the site). The lateral movement of the implement can be derived from the signals of the feedback sensors  70 ,  72  and/or another feedback sensor (not depicted) located between the draw bar  14  and the coupling  28 , and/or an individual position-determining device  74  is allocated to the implement  12 , or for the purpose, a kinematic model (see WO 2008/005159 A2) is used for the combination of the tractor  10  and the implement  12 . 
         [0022]    In the following step  104 , the lateral distribution of the crops in the container  46  is detected by the sensors  50 . Then step  106  follows, in which the theoretical positions for the actuators  54  and  58  are calculated. They are determined in such a way that, on the one hand, the processing element  36  is still orthogonal to the theoretical line  66  even after the traversing of the distance x; on the other hand, however, the distribution of the crops in the container corresponds to the filling strategy, which can, for example, imply that first the left half of the bale is built up to a diameter of 10% of the desired bale size, then the right half is built up to a diameter of 20% of the desired bale size, then, in turn, the left half of the bale is built up to a diameter of 30%, etc. In this respect, one can additionally refer to the state of the art according to EP 1 634 491 A1 and EP 1 813 146 A2, whose disclosures are incorporated in the documentation under consideration by reference. 
         [0023]    In step  106 , then, signals for the valve arrangement  56  are determined and transmitted, which are based on the result of step  104  and the initial values of the sensors  70 ,  72  with regard to the up-to-date positions of the actuators  54  and  58 . Step  102  follows, in turn. 
         [0024]    It should be noted that other refinements would also be possible. Thus, the tractor  10  and/or the implement  12  could be equipped with an inclination sensor (not depicted) for the detection of the side inclination of the ground, whose signals are supplied to the control device  52 . The control device  52  can then steer the implement  12  upwards on the slope, so as to compensate for slippage. The signals of the inclination sensor can also be used in order to place the implement  12  parallel to the slope before automatically ejecting a bale and thus preventing it from rolling down the slope. 
         [0025]    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.