Patent Publication Number: US-2021185921-A1

Title: Agricultural apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.K. Application No. GB1918842.4, filed Dec. 19, 2019, which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     Field 
     The present invention relates to an agricultural apparatus comprising an agricultural vehicle and a number of work units suitable for generating swathes of cut crop, and in particular to a mowing apparatus for cutting a standing crop such as hay. 
     Description of Related Art 
     It is known to provide a mower combination in which a first mower unit is located ahead of an agricultural vehicle such as a tractor with two further lateral mower units trailing the agricultural vehicle. The rear mower units can optionally be provided with conveyors for depositing cut crop into a swath or swathes behind the agricultural vehicle. 
     During operation each of the lateral mower units are suspended from a central frame unit by suitably located hydraulic units. The hydraulic unit may be used to move the mower units from a working position to a transport position. A headland position may be defined between the working position and the transport position. In the working position the height of the lateral mower units above the ground surface may be further controlled by operation of the hydraulic units. 
     The mower units may be provided with rollers or runners to rest on the ground to be mowed. Ideally the mower units are supported so that the weight of the mower units is not on the ground surface or turf being cut. This is achieved by adjusting the relief pressure in the hydraulic units to reduce the bearing force of the mower unit. The higher the pressure relief the lower the bearing force. However in the case of varying terrain, due to hydraulic unloading the mower units do not follow the terrain contour resulting in an unclean cut. Also, the low contact pressures and high speed of operation of the mower units leads to an uneven cut since the mower units do not adapt to the terrain contour due to inertia in the hydraulic relief system. 
     It is an advantage of the present invention that these problems are addressed. 
     Other advantages of the present invention will become apparent as discussed below. 
     SUMMARY 
     According to a first aspect of the present invention, an agricultural apparatus comprises an agricultural vehicle and a number of work units suitable for cutting a standing crop, the work units being connected to the agricultural vehicle, the number of work units including a front work unit and two lateral work units located behind and to the sides of the front work unit, each of the work units depositing the cut crop as a swath, each of the lateral work units being supported from a central chassis by a hydraulic system, the agricultural apparatus further comprising a control unit and a plurality of sensors, the sensors determining a speed of the agricultural vehicle, a speed of operation of each lateral work unit and a relief pressure in the hydraulic system of each lateral work unit, the control unit being configured to receive inputs from the plurality of sensors, compare the values for a desired vehicle speed or speed of operation of the work unit and adjusting the pressure relief in the hydraulic system based on this comparison. 
     This has as an advantage that when an increase in speed is detected, the inertia of the hydraulic control system can be compensated for and the work units are able to follow the terrain contour, resulting in an even cut. Similarly if a decrease in speed is detected the bearing pressure can be reduced. 
     Preferably, agricultural apparatus further includes a plurality of sensors to detect an overload condition in each of the work units, the control unit compares a speed of operation of each work unit before and after an overload protection and the speed of the agricultural vehicle and adjusts the speed of the agricultural vehicle based on this comparison. 
     More preferably the plurality of sensors comprises a plurality of sensors to measure the torque of the PTO driving the front and rear work units. 
     Preferably a threshold value for the speed of operation of each work unit is set such that the agricultural vehicle may not speed up until such threshold value has been reached. 
     Preferably a maximum torque value may be stored such that if the maximum torque value is exceeded then the operating speed of the work unit is reduced. Preferably a minimum torque value is stored such that if the minimum torque value is undershot, the speed of operation of the work unit is increased. 
     Preferably a hysteresis pattern may be stored allowing alteration of the speed of operation of the work unit in response to the detected torque of the PTO. 
     This has as an advantage that the operator no longer needs constantly to monitor the speed of the agricultural vehicle and the operating speeds of the work units thereby reducing the stress and tiredness of the operator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a plan view of an agricultural apparatus for use in the present invention; 
         FIG. 2  shows a schematic view of elements of an agricultural apparatus for use in the present invention; 
         FIG. 3  shows a flow diagram illustrating an example load control method in accordance with the present invention; and 
         FIG. 4  shows a flow diagram illustrating an example vehicle speed or work unit control method in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     The invention will now be described in the following detailed description with reference to the drawings, wherein preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. But to the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description. 
     Reference to terms such as longitudinal, transverse and vertical are made with respect to a longitudinal vehicle axis which is parallel to a normal forward direction of travel. 
     With reference to  FIG. 1 , a plan view of an agricultural apparatus  2  for use in the present invention is shown. 
     An agricultural apparatus  2  comprises an agricultural vehicle  4  such as a tractor and a number of work units  6 , 8 , 10  suitable for cutting standing crop, the work units  6 , 8 , 10  being connected to the agricultural vehicle. The work units include a front work unit  6  located to the front of the agricultural vehicle  4  and two lateral work units  8 , 10  located behind and to the sides of the front work unit  6 , each of the work units  6 , 8 , 10  depositing cut crop as a swath. The front work unit  6  is conveniently mounted on a front hitch  12  of the agricultural vehicle  4 . The two lateral work units  8 , 10  are conveniently mounted on a central chassis supported from a rear hitch  14  of the agricultural vehicle  4 . In a preferred embodiment the work units comprise mowing units. 
     The work units  6 , 8 , 10  may conveniently be driven from a PTO (Power Take Off) drive provided to the front and to the rear of the agricultural vehicle  2 . 
     The lateral work units  8 , 10  are supported from a central chassis by hydraulic units  22 , 24 . Each hydraulic unit  22 , 24  may be used to move a respective lateral work unit  8 , 10  from a working position to a transport position. A headland position may be defined between the working position and the transport position. In the working position the height of each of the lateral work units  8 , 10  above the ground surface may be further controlled by operation of the hydraulic units  22 , 24 . 
     In the illustrated embodiment a swath  20  produced by the front work unit  6  is shown. In practice conveyors  16 , 18  mounted to the rear of the lateral work units  8 , 10  will direct cut crop material to one side or the other of the respective lateral work units  8 , 10  to produce a broader central swath or one or more additional swathes as desired. These swathes are omitted from  FIG. 1  for clarity. 
     An operator can control operation of the front and rear work units  6 , 8 , 10  from within the agricultural vehicle  4  by use of a suitable user terminal  30 . For example the operator can cause each of the work units  6 , 8 , 10  to move from a working position to a headland position, can cause the rear work units  8 , 10  to move from the working position to a transport position, or can cause the conveyors  16 , 18  to move from an active position to an inactive position. 
     The user terminal  30  communicates with an electronic control unit  32 . The control unit  32  provides signals to control operation of the front and rear hitches  12 , 14  of the agricultural vehicle  4  and provides signals to control operation of the work units  6 , 8 , 10 . Conveniently the signals are provided by way of a data communication network such as one compliant with the ISOBUS standard. 
     The control unit  32  may conveniently comprise a single processor located on the agricultural vehicle or its functions may be split between a processor located on the agricultural vehicle and one or more additional processors located on the work units, the additional processor(s) being in electronic communication with the first processor. 
     The control unit  32  is also able to access a suitable memory  34 . The memory  34  may take any suitable form and is in electronic communication with the control unit  32 . The memory  34  is adapted to store, in any suitable manner such as a database or look up table, a vehicle speed and/or the mower speed with respective target values for the relief pressure in each hydraulic unit  22 , 24 . 
     The agricultural apparatus  2  further comprises a plurality of sensors including a sensor  36  for determining a speed of the agricultural vehicle, a sensor  38  for determining a speed of operation of each lateral mower unit and a sensor  40  for determining a relief pressure in the hydraulic system of each hydraulic unit. 
     The control unit is configured to receive inputs from the plurality of sensors  36 , 38 , 40  and to compare the values for a desired vehicle speed or speed of operation of the mower unit and, as required, adjusting the pressure relief in the hydraulic system based on this comparison. 
     For example if the working speed increases, the control unit  32  detects the increase in in the speed signal (step  100   FIG. 3 ) and adjusts the relief pressure in the hydraulic system to increase the contact pressure of the work unit (step  102 ). Because the contact pressure has been increased, the inertia of the hydraulic system can be compensated for and the work units will adapt to the terrain contour resulting in a clean cut. 
     Alternatively, when a decrease in speed is detected, the bearing pressure is reduced by adjusting the pressure relief in the hydraulic system accordingly. In this way, the control unit  32  is able to regulate the contact pressure according to the speed dependent operating parameters. 
     In a further embodiment, the agricultural apparatus  2  is further provided with a plurality of sensors  42 , 44  to detect an overload condition in each of the lateral work units  8 , 10 . Conveniently the plurality of sensors  42 , 44  comprise sensors adapted to measure the torque of the PTO driving the front work unit and driving the rear work units. The control unit  32  receives inputs relating to torque values (step  200 ) and notes the detection of an overload condition corresponding to a change in torque values and compares a speed of operation of each work unit before and after the overload condition and the speed of the agricultural vehicle  4 . 
     The control unit  32  is then able to adjust the speed of the agricultural vehicle  4  based on this comparison (step  202 ). In a preferred embodiment, the control unit  32  monitors the operating speed of the work units  8 , 10  and compares this value against a stored threshold value to ensure that a minimum threshold value for the speed of operation of the work units  8 , 10  has been achieved. Only when this condition has been met does the control unit  32  increase the speed of the agricultural vehicle  4 . 
     A value for the maximum desired torque value may be stored. The control unit  32  is adapted to reduce the operating speed of the work unit  8 , 10  if the maximum desired torque value is met or exceeded. Additionally a value for the minimum desired torque value may be stored. The control unit  32  is adapted to increase the operating speed of the work unit  8 , 10  if the minimum desired torque value is met or exceeded. It can be seen that a hysteresis pattern may be stored allowing alteration of the operating speed of the work units  8 , 10  in response to changes in the detected torque of the work units  8 , 10 . 
     From reading the present disclosure, other modifications will be apparent to persons skilled in the art. Such modifications may involve other features which are already known in the field of mowers and component parts therefore and which may be used instead of or in addition to features already described herein.