Abstract:
A large round baler is equipped with a pick-up mounted to the baler frame for being raised and lowered relative to the ground by operation of a hydraulic cylinder. The pick-up is maintained at a desired working height by a control arrangement including at least one height sensor which sends a signal corresponding to the instant height of the pick-up above the ground to a signal processing unit which compares the height signal with a stored value corresponding to a desired height, the signal processing unit the sending a control signal for controlling a solenoid-operated valve in such a way that the hydraulic cylinder is caused to move the pickup in the required direction for maintaining the desired height.

Description:
FIELD OF THE INVENTION  
         [0001]    The invention pertains to a device for adjusting a crop pick-up on an agricultural baling press, with the adjustment device containing an adjustment mechanism for varying the distance between the pick-up and the ground.  
         BACKGROUND OF THE INVENTION  
         [0002]    Baling presses, in particular, modern round balers according to WO-A1-98/17096, are provided with so-called pick-ups that are intended for picking up the widest swaths possible in order to achieve a high cropping capacity. In order to ensure that the pick-up always maintains a certain distance from the ground, the pick-up is provided with support wheels that can be mounted on the pick-up in different positions. However, this desired spacing of the pick-up from the ground is not achieved when ground conditions are such that the pick-up sinks into the ground and its tines engage the ground. The support wheels are laterally adjustable so that they do not protrude beyond the lateral dimensions of the baling press during its transport.  
           [0003]    The problem to be solved by the invention is the considerable structural expense associated with the mounting and adjustment of the support wheels and the fact that the wheels sometimes do not achieve the desired spacing, and crop sometimes builds up around the wheel support structure.  
         SUMMARY OF THE INVENTION  
         [0004]    According to the present invention, there is provided an improved pick-up height adjusting device.  
           [0005]    A broad object of the invention is to provide a pick-up height adjusting device that is relatively inexpensive and easily operated to achieve reliable, adjustable height maintenance.  
           [0006]    A more specific object of the invention is to provide a pick-up height adjusting device which eliminates the need for pick-up support wheels. This is achieved by using a contact-free height sensor such as a high-frequency or ultrasonic sensor.  
           [0007]    Another object of the invention is to provide an alternate sensor, which while in contact with the ground, is in the form of a feeler having the ability to penetrate dense weeds which cause the contact-free sensor to deliver a false height signal.  
           [0008]    These and other objects will become apparent from a reading of the ensuing description together with the appended drawing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The sole FIGURE is a schematic right side view of a large round baler and towing tractor, with the baler having a pick-up equipped with a height adjusting device constructed in accordance with the principles of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0010]    Referring now to the drawing, there is shown a baling press  10  having a frame  12 , a baling chamber  14 , wheels  16 , a hitch  18  and a pick-up  20 , with the hitch  18  being coupled to the drawbar of a towing vehicle  22 .  
         [0011]    In the embodiment shown, the baling press  10  is realized in the form of a round baler, with the baling chamber  14  being of a fixed size. Alternatively, the baling press  10  may also have a different design, e.g., in the form of a round baler with a baling chamber of variable size, a baling press for producing small or large square bales, or a similar towed machine with a pick-up.  
         [0012]    The baling press frame  12  is realized in the form of a welded frame and carries side walls  24 , between which roll-like pressing elements  26  extend.  
         [0013]    The baling chamber  14  is closed on the ends by the side walls  24  and on the circumference by the pressing elements  26 . The pressing elements  26  are arranged so that an inlet  28 , through which the crop can be fed into the baling chamber  14 , remains situated on the lower front side.  
         [0014]    The wheels  16  support the frame  12  and the entire baling press  10  on the ground. The hitch  18  serves for connecting the frame  12  to the towing vehicle  22  and essentially extends horizontally above the pick-up  20 .  
         [0015]    The pick-up  20  is realized conventionally, i.e., it is equipped with several revolving rows of spring-loaded prongs  30 . These prongs revolve above the ground so that the crop is lifted off the ground and transported toward the rear, i.e., to the inlet  28 . Although this is not absolutely imperative, a rotary conveyor  32  is provided between the pick-up  20  and the inlet  28 . The pick-up  20  is conventionally mounted on the frame  12  so that it can be pivoted and adjusted vertically by means of an adjustment mechanism  34  that forms part of an adjusting device  35 .  
         [0016]    The position of the pick-up  20  should be chosen so that the prongs  30  turn a short distance above the ground. However, this applies to the entire width of the pick-up  20 . This is intended to prevent the pick-up from being lowered when part or all of the pick-up briefly moves over a depression or the like. On the other hand, the pick-up  20  should be raised into the non-operating position when the baling press  10  is transported.  
         [0017]    The adjusting device  35  contains a control unit  36  in order to control or regulate the distance between the pick-up  20  and the ground. This control unit contains a sensor  38 , a signal processing unit  40 , an input unit  42 , a power supply  44  and various connecting lines which ultimately act upon the adjustment mechanism  34 .  
         [0018]    The adjustment mechanism  34  may be simply realized in the form of a single-action hydraulic cylinder that is controlled by a conventional solenoid-operated valve (not shown). A single-acting hydraulic motor or hydraulic cylinder suffices because the downward movement is caused by gravitational force. However, the adjustment speed can be increased by using a double-acting hydraulic cylinder. It would also be conceivable to use an electric motor with a spindle drive instead of the hydraulic cylinder. The adjustment mechanism  34  can also be operated from the towing vehicle  22  independently of the signal processing unit  40  in order to raise the pick-up  20  into its transport position and/or lower the pick-up onto the ground. In the embodiment shown, the adjustment mechanism  34  only acts over part of the maximum adjusting distance of the pick-up  20 , i.e., to the extent of the required adjustment during its operation. In other respects, the pick-up  20  is able to move freely upward relative to the adjustment mechanism  34 . When raising the pick-up  20  into the transport position, a servomotor  37  arranged on the pick-up  20  and the frame  12  is actuated so that the pick-up  20  is completely raised. As soon as the servomotor  37  is no longer pressurized, the pick-up  20  is lowered into a position in which it is carried by the adjustment mechanism  34 . However, it is not necessary to use the servomotor  37 . In instances in which no separate servomotor  37  is used, the entire movement is effected by means of the adjustment mechanism  34 .  
         [0019]    It is advantageous if the control unit  36  is partially arranged on the baling press  10  and partially arranged on the towing vehicle  22 . In an embodiment variant, the control unit  36  is arranged only on the baling press  10  and can be remote-controlled from the towing vehicle  22 ; the control unit may be realized electrically, electronically, in accordance with CAN-bus technology or the like.  
         [0020]    In the embodiment shown, the sensor  38  is realized in the form of a contact-free sensor  38  that transmits high-frequency or ultrasonic waves toward the ground and utilizes the reflection behavior of the waves for calculating the distance traveled. The sensor then derives a signal for the distance between the pick-up  20  and the ground from the distance traveled. In the drawing, the sensor  38  is situated within the contour of the front part of the pick-up  20 . Such an arrangement may, for example, be realized by mounting the sensor  38  in the pick-up  20  between adjacent moving paths of the prongs  30 . Alternatively, or additionally, the sensor  38  may be arranged in front of the pick-up  20  and carried by a corresponding arm, as indicated at  39  in broken lines. In a further alternate arrangement, for use when weeds are such as to interfere with the signal generated by the sensor  38 , a sensor arrangement for replacing each sensor  38  is used and includes a sensor  41  including a feeler or sliding element, pivotally mounted to the pick-up  20 , that follows the contour of the ground. It is known practice with such sensors to use a spring to bias the feeler against the ground and to use a potentiometer associated with the feeler for creating a signal for determining the distance that the pick-up is from the ground as a function of the angular displacement of the feeler. The feeler of the sensor  41  is mounted such that it may be folded to a stored position when not needed. Of course, when the ground-contacting sensors  41  are used, a signal is sent to the signal processing unit  40  for disabling the processing of any signals generated by the sensors  38  or they are somehow disabled so as not to operate at all.  
         [0021]    In this embodiment, three sensors  38  are arranged over the width of the pick-up  20 , in a manner not shown, so that one sensor is in the center and the other two are at the opposite lateral sides of the pick-up. The signal processing unit  40  selects the signal that represents the shortest distance from the ground from the signals delivered by the three sensors  38 .  
         [0022]    The signal processing unit  40  is realized in the form of an on-board computer and is usually arranged on the towing vehicle  22 . If so required, the signal processing unit  40  may also be realized so that it can be detached. In this case, the signal processing unit is portable and can be used in another towing vehicle. The signal processing unit  40  is hardware- and or/ software-based; however, the signal processing unit preferably contains a computer program that allows a series of arithmetic and logic operations. Power from the power supply  44  of the towing vehicle  22  is fed to the signal processing unit  40  in order to perform the computations. In addition, the signal processing unit  40  receives the signal or signals from the sensor(s)  38  so that the current distance from the ground can be obtained or calculated. If the signal processing unit  40  receives signals from several sensors  38 , the signal that corresponds to the shortest distance from the ground can be obtained or calculated. If so required, a timing element may also be used to prevent brief signal changes from negligible contour variations from being processed. A line leads from the signal processing unit  40  to the adjustment mechanism  34  in order to forward an extension or retraction signal to the adjustment mechanism.  
         [0023]    The input unit  42  is usually realized in the form of a keyboard and is suitable for adjusting certain minimum heights or initiating certain operating states. For example, a more or less aggressive raking process to be carried out by the prongs  30  can be adjusted. In addition, the pick-up  20  can be raised into transport position. It is possible to arrange the signal processing unit  40  on the baling press  10  and to arrange the input unit  42  on the towing vehicle  22 .  
         [0024]    The power supply  44  usually consists of the 12 volt voltage source of the towing vehicle. However, it would, in principle, also be possible to realize the power supply in the form of a battery arranged in the signal processing unit  40  or in the form of a solar cell.  
         [0025]    A deactivating device  46  is provided as part of the signal processing unit  40  in order to ensure that the pick-up  20  maintains its transport position, for example. In the embodiment shown, the deactivating device  46  is realized in the form of a contact switch that delivers a signal to the signal processing unit  40 . Based on this signal, the signal processing unit  40  recognizes that the pick-up  20  has reached its transport position and should no longer be adjusted in accordance with the signals of the sensors  38 .  
         [0026]    The operation of the invention will now be discussed in accordance with the previous description.  
         [0027]    During its operation, the baling press  10  is moved over a field with the aid of the towing vehicle  22  and is activated. The signal processing unit  40  is activated so that the sensors  38  determine the distance between the pick-up  20  and the ground and adjust the adjustment mechanism  34  in accordance with the value input by means of the input unit  42 . As the baling press  10  is towed over the field, the sensors  38  recognize changes in the distance from the ground and forward this information to the signal processing unit  40 , where said information is compared with a set value. Depending on the direction of the deviation, the adjustment mechanism  34  is either extended or retracted so that the actual value and the set value match. Once the pick-up  20  is raised into its transport position again by means of the servomotor  37 , the software or hardware computations carried out by the signal processing unit  40  are stopped again based on the signal received from the deactivation device  46 .  
         [0028]    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.