Apparatus, systems and methods for row unit downforce control

Abstract

Systems, methods and apparatus for controlling the downforce applied to a row unit of an agricultural implement having multiple row units. A downpressure control device in fluid communication with a down chamber of the least one actuator maintains as a selected downpressure, any one of a continuous range of pressures in the downpressure chamber. Pressure in the down chamber tending to oppose pressure in the lift chamber of the at least one actuator.

1 . A downforce control system for a plurality of row units of an agricultural planter, each of the plurality of row units supported from a toolbar of the agricultural planter, each of the plurality of row units having an opening disc and a gauge wheel, the gauge wheel limiting a depth of penetration of the opening disc into a soil surface, the downforce control system comprising:
 a plurality of downforce sensors, each downforce sensor disposed on a respective one of the plurality of row units, wherein each downforce sensor is configured to generate a measured downforce signal related to a measured downforce on the soil surface by the gauge wheel of the respective one row unit;   a plurality of actuators, each actuator having a down chamber and a lift chamber, each actuator coupled at a first end to the toolbar and at a second end to a corresponding one of the plurality of row units;   a plurality of down pressure control devices, each down pressure control device in fluid communication with the down chamber of a corresponding one of the plurality of actuators, each down pressure control device in fluid communication with a fluid supply line and a fluid return line;   a common lift pressure control device in fluid communication with the lift chamber of each of the plurality of actuators, the common lift pressure control device in fluid communication with the fluid supply line and the fluid return line;   a monitor in signal communication with each of the plurality of downforce sensors, each of the plurality of down pressure control devices, and the common lift pressure control device, wherein the monitor is configured to command the common lift pressure control device to establish a commanded common lift pressure in the lift chamber of each of the plurality of actuators and wherein the monitor is configured to separately command each down pressure control device to establish a commanded down pressure in the down chamber of the corresponding one actuator of the corresponding one row unit based the commanded common lift pressure and the measured downforce signal of the downforce sensor of the respective one row unit to which the corresponding one actuator is coupled, so as to maintain a desired net pressure of each one of the plurality of actuators, wherein the desired net pressure of each one of the plurality of actuators is a sum of the commanded down pressure in its down chamber less the commanded common lift pressure in its lift chamber.   
     
     
         2 . The downforce control system of  claim 1 , wherein each of the plurality of down pressure control devices comprises a down pressure reducing-relieving valve, and wherein the fluid supply line and the fluid return line are in fluid communication with respective tank ports of the down pressure reducing-relieving valve and wherein the down chamber of the corresponding one actuator is in fluid communication with the work port of the down pressure reducing-relieving valve. 
     
     
         3 . The downforce control system of  claim 1 , wherein the common lift pressure control device comprises a lift pressure reducing-relieving valve, and wherein the fluid supply line and the fluid return line are in fluid communication with respective tank ports of the lift pressure reducing-relieving valve and wherein the lift chamber of each of the plurality of actuators is in fluid communication with a work port of the lift pressure reducing-relieving valve. 
     
     
         4 . The downforce control system of  claim 2 , wherein the monitor is in signal communication with a solenoid associated with the down pressure reducing-relieving valve, and wherein the monitor is configured to send a control current to the solenoid to set the down pressure proportional to the control current. 
     
     
         5 . The downforce control system of  claim 3 , wherein the monitor is in signal communication with a solenoid associated with the lift pressure reducing-relieving valve, and wherein the monitor is configured to send a control current to the solenoid to set the lift pressure proportional to the control current. 
     
     
         6 . The downforce control system of  claim 1 , wherein each of the plurality of down pressure control devices is a electro-hydraulic flow control servo valve and the common lift pressure control device is a electro-hydraulic flow control servo valve. 
     
     
         7 . The downforce control system of  claim 6 , further comprising: a plurality of pressure transducers, each disposed to measure the down pressure in the down chamber of each of the plurality of actuators. 
     
     
         8 . The downforce control system of  claim 1 , wherein the desired net pressure is a desired pressure range. 
     
     
         9 . The downforce control system of  claim 8 , wherein the desired pressure range is between a defined maximum pressure and a defined minimum pressure. 
     
     
         10 . The downforce control system of  claim 9 , wherein the defined maximum pressure is a maximum operating pressure of the actuator and the defined minimum pressure is a minimum operating pressure of the actuator. 
     
     
         11 . The downforce control system of  claim 10 , wherein the maximum operating pressure is approximately 3000 psi and the minimum operating pressure is approximately 0 psi. 
     
     
         12 . The downforce control system of  claim 9 , wherein the defined maximum pressure is a pressure less than the maximum operating pressure of the actuator by an upper band amount and wherein the defined minimum pressures is a pressure greater than the minimum operating pressure of the actuator by a lower band amount. 
     
     
         13 . The downforce control system of  claim 8 , wherein the desired pressure range is a midrange operating pressure of the actuator. 
     
     
         14 . The downforce control system of  claim 13 , wherein the midrange operating pressure of the actuator is approximately ½ of a maximum operating pressure of the actuator. 
     
     
         15 . The downforce control system of  claim 1 , wherein the plurality of actuators in fluid communication with the common lift pressure control device consists of all of the actuators of all of the row units of the agricultural planter. 
     
     
         16 . The downforce control system of  claim 1 , wherein the plurality of actuators in fluid communication with the common lift pressure control device consists of the actuators of at least two of the plurality of row units of the agricultural planter. 
     
     
         17 . The downforce control system of  claim 1 , wherein the plurality of actuators in fluid communication with the common lift pressure control device consists of all of the actuators of the plurality of row units on a section of the agricultural planter. 
     
     
         18 . The downforce control system of  claim 1 , wherein the commanded common lift pressure is based on a soil penetration criterion, and wherein the soil penetration criterion is based on any one of: (i) a predefined minimum net pressure of each of the plurality of actuators; (ii) a minimum measured downforce signal of the downforce sensor of each of the plurality of row units; and (iii) a minimum down pressure measurement in the down chamber of the actuator measured by a pressure transducer in communication with the down chamber of each of the plurality of actuators. 
     
     
         19 . The downforce control system of  claim 1 , wherein each of the plurality of actuators comprises a two-stage actuator, wherein the two-stage actuator includes a supplemental down chamber and wherein the downforce control system further comprises:
 a common supplemental down pressure control device, the common supplemental down pressure control device in fluid communication with the supplemental down chamber of each of the plurality of two-stage actuators; and   wherein the monitor is configured to command a commanded common supplemental down pressure in the supplemental down chamber of each of the plurality of two-stage actuators.   
     
     
         20 . The downforce control system of  claim 19 , wherein the desired net pressure of each one of the plurality of actuators comprising the two-stage actuator is a sum of the commanded down pressure in its down chamber and commanded common supplemental down pressure in its supplemental down chamber less the commanded common lift pressure in its lift chamber. 
     
     
         21 . The downforce control system of  claim 20 , further comprising:
 a first control device comprising a solenoid-operated bi-directional poppet and a flow control valve in fluid communication with the supplemental down chambers of each of the plurality of two-stage actuators;   a second control device comprising a solenoid-operated bi-directional poppet valve in fluid communication with the common lift pressure control device and the lift chamber of each of the plurality two-stage actuators;   a third control device comprising a solenoid-operated bi-directional poppet valve in fluid communication with the common supplemental down pressure control device and the supplemental down chamber of each of the plurality of two stage actuators;   the monitor in signal communication with each of the first, second and third control devices;   wherein the monitor is configured to open the second control device, close the third control device and open the first control device to allow fluid flow between the supplemental down chamber and the lift chamber of each of the plurality of two-stage actuators, and wherein the monitor is configured to close the second control device, open the third control device and open the first control device to allow fluid flow from the lift chamber to the supplemental down chamber of each of the plurality of two-stage actuators.   
     
     
         22 . A method of maintaining optimal downforce on each of a plurality of row units of an agricultural planter, each of the plurality of row units supported from a toolbar of the agricultural planter, each of the plurality of row units including an opening disc and a gauge wheel, the gauge wheel limiting a depth of penetration of the one opening disc into a soil surface, each row unit including an actuator coupled thereto, each actuator having a down chamber and a lift chamber, the method comprising:
 via a monitor in signal communication with a plurality of downforce sensors, a common lift pressure control device and a plurality of down pressure control devices, wherein each of the plurality of downforce sensors is disposed on a respective one of the plurality of row units, and wherein the common lift pressure control device is in fluid communication with the lift chamber of the actuator coupled to each of the plurality of row units, and wherein each respective one of the plurality of down pressure control devices is in fluid communication with the down chamber of the actuator coupled to each of the plurality of row units, whereby:   each of the plurality of downforce sensors generating a measured downforce signal related to a measured downforce on the soil surface by the gauge wheel of the respective one row unit;   commanding the common lift pressure control device to establish a common lift pressure in the lift chamber of each actuator of each of the plurality of row units;   determining a desired net pressure for the actuator of each of the plurality of row units based on the generated measured downforce signal for each respective one row unit and the commanded common lift pressure; and   commanding each down pressure control device to establish a down pressure in the down chamber of the actuator of the respective one row unit to which the actuator is coupled so that a sum of the commanded down pressure in the down chamber less the commanded lift pressure in the lift chamber of the actuator of the respective one row unit approximates the desired net pressure.   
     
     
         23 . The method of  claim 22 , wherein each of the plurality of down pressure control devices comprises a down pressure reducing-relieving valve, and wherein the fluid supply line and the fluid return line are in fluid communication with respective tank ports of the down pressure reducing-relieving valve and wherein the down chamber of the actuator is in fluid communication with the work port of the down pressure reducing-relieving valve. 
     
     
         24 . The method of  claim 22 , wherein the common lift pressure control device comprises a lift pressure reducing-relieving valve, and wherein the fluid supply line and the fluid return line are in fluid communication with respective tank ports of the lift pressure reducing-relieving valve and wherein the lift chamber of the actuator is in fluid communication with a work port of the lift pressure reducing-relieving valve. 
     
     
         25 . The method of  claim 24 , wherein the monitor is in signal communication with a solenoid associated with the down pressure reducing-relieving valve, and wherein the monitor is configured to send a control current to the solenoid to set the down pressure proportional to the control current. 
     
     
         26 . The method of  claim 25 , wherein the monitor is in signal communication with a solenoid associated with the lift pressure reducing-relieving valve, and wherein the monitor is configured to send a control current to the solenoid to set the lift pressure proportional to the control current. 
     
     
         27 . The method of  claim 22 , wherein each of the plurality of down pressure control devices is an electro-hydraulic flow control servo valve and the common lift pressure control device is an electro-hydraulic flow control servo valve. 
     
     
         28 . The method of  claim 27 , further comprising: a plurality of pressure transducers, each disposed to measure the down pressure in the down chamber of the actuator of each of the plurality of row units. 
     
     
         29 . The method of  claim 22 , wherein the desired net pressure is a desired pressure range. 
     
     
         30 . The method of  claim 29 , wherein the desired pressure range is between a defined maximum pressure and a defined minimum pressure. 
     
     
         31 . The method of  claim 30 , wherein the defined maximum pressure is a maximum operating pressure of the actuator and the defined minimum pressure is a minimum operating pressure of the actuator. 
     
     
         32 . The method of  claim 31 , wherein the maximum operating pressure is approximately 3000 psi and the minimum operating pressure is approximately 0 psi. 
     
     
         33 . The method of  claim 31 , wherein the defined maximum pressure is a pressure less than the maximum operating pressure of the actuator by an upper band amount and wherein the defined minimum pressures is a pressure greater than the minimum operating pressure of the actuator by a lower band amount. 
     
     
         34 . The method of  claim 29 , wherein the desired pressure range is a midrange operating pressure of the actuator. 
     
     
         35 . The method of  claim 34 , wherein the midrange operating pressure of the actuator is approximately ½ of a maximum operating pressure of the actuator. 
     
     
         36 . The method of  claim 22 , wherein the common lift pressure control device is in fluid communication with the lift chamber of the actuator of every one of the plurality of row units disposed on the toolbar of the agricultural planter. 
     
     
         37 . The method of  claim 22 , wherein the common lift pressure control device is in fluid communication with the lift chamber of the actuator of at least two of the plurality of row units of the agricultural planter. 
     
     
         38 . The method of  claim 22 , wherein the common lift pressure control device is in fluid communication with the lift chamber of the actuators of all of the plurality of row units on a section of the agricultural planter. 
     
     
         39 . The method of  claim 29 , further comprising:
 via the monitor, determining whether the commanded down pressure in the down chamber of the corresponding actuator of any one of the plurality of row units is outside the desired range, whereby:   if the down pressure in the down chamber of the corresponding actuator of at least one of the plurality of row units is above the desired range and if no down pressure in the down chamber of the corresponding actuator of any one of the plurality of row units is below the desired range, the monitor commands the common lift pressure control device to decrease the common lift pressure;   if the down pressure in the down chamber of the correspond actuator of at least one of the plurality of row units is below the desired range and if no down pressure in the down chamber of the correspond actuator of any one of the plurality of row units is above the desired range, the monitor commands the common lift pressure control device to increase the common lift pressure;   if the down pressure in the down chamber of the corresponding actuator of at least one of the plurality of row units is above the desired range and if no down pressure in the down chamber of the corresponding actuator of any of the plurality of row units is below the desired range, the monitor commanding the common lift pressure control device to decrease the common lift pressure.   
     
     
         40 . The method of  claim 34 , further comprising:
 via the monitor:   determining an average commanded down pressure by averaging commanded down pressure in the down chamber of the corresponding actuator of each of the plurality of row units;   comparing the average commanded down pressure to the midrange operating pressure of the actuator, whereby:   if the average commanded down pressure is below the midrange operating pressure, the monitor commands the common lift pressure control device to increase the common lift pressure;   if the average commanded down pressure is above the midrange operating pressure, the monitor commands the common lift pressure control device to decrease the common lift pressure; and   if the average commanded down pressure is substantial equal to the midrange operating pressure, the monitor retains the commanded lift pressure.   
     
     
         41 . The method of  claim 22 , wherein the common lift pressure is based on a soil penetration criterion, and wherein the soil penetration criterion is based on any one of: (i) a predefined minimum net pressure of each of the plurality of actuators; (ii) a minimum measured downforce signal of the downforce sensor of each of the plurality of row units; and (iii) a minimum down pressure measurement in the down chamber of the actuator measured by a pressure transducer in communication with the down chamber of each of the plurality of actuators. 
     
     
         42 . The method of  claim 41 , further comprising:
 via the monitor, determining if the soil penetration criteria is within a desired range, whereby:   if the soil penetration criteria is determined to be within the desired range for each of the plurality of row units, the monitor maintains the commanded common lift pressure;   if the soil penetration criteria is determined to be above the desired range for any one of the plurality of row units and not below the desired range for any of the plurality of row units, the monitor commands the common lift pressure control device to decrease the common lift pressure;   if the soil penetration criteria is determined to be below the desired range for any one of the plurality of row units and not above the desired range for any of the plurality of row units, the monitor commands the common lift pressure control device to increase the common lift pressure;   if the soil penetration criteria is determined to be below the desired range for at least one of the plurality of row units and is above the desired range for at least one of the plurality of row units, the monitor commands the common lift pressure control device to decrease the common lift pressure.   
     
     
         43 . The method of  claim 22 , wherein each of the plurality of actuators comprises a two-stage actuator, wherein the two-stage actuator includes a supplemental down chamber, the method further comprising:
 via the monitor in further signal communication with a common supplemental down pressure control device, and wherein the common supplemental down pressure control device is in fluid communication with the supplemental down chamber of each of the plurality of two-stage actuators;   wherein the step of determining the desired net pressure of each one of the plurality of actuators comprising the two-stage actuator is a sum of the commanded down pressure in its down chamber and commanded common supplemental down pressure in its supplemental down chamber less the commanded common lift pressure in its lift chamber; and   wherein the step of commanding each down pressure control device to establish a down pressure in the down chamber of the actuator comprising the two-stage actuator of the respective one row unit to which the two-stage actuator is coupled includes establishing the commanded down pressure so that the commanded down pressure in the down chamber and the commanded supplemental down pressure in the supplemental down chamber less the commanded lift pressure in the lift chamber of the two-stage actuator of the respective one row unit approximates the desired net pressure.   
     
     
         44 . The method of  claim 43 , further comprising:
 wherein a first control device comprising a solenoid-operated bi-directional poppet and a flow control valve is in fluid communication with the supplemental down chambers of each of the plurality of two-stage actuators;   wherein a second control device comprising a solenoid-operated bi-directional poppet valve is in fluid communication with the common lift pressure control device and the lift chamber of each of the plurality two-stage actuators;   wherein a third control device comprising a solenoid-operated bi-directional poppet valve is in fluid communication with the common supplemental down pressure control device and the supplemental down chamber of each of the plurality of two stage actuators;   wherein the monitor is in signal communication with each of the first, second and third control devices;   whereby to decrease an amount of time and fluid flow when it is desired to stop applying supplemental down pressure and to start applying lift pressure to each of the two-stage actuators, the monitor opens the second control device, closes the third control device and opens the first control device to allow fluid flow between the supplemental down chamber and the lift chamber of each of the plurality of two-stage actuators; and   whereby to decrease an amount of time and fluid flow when it is desired to stop applying lift pressure and to start applying supplemental down pressure to each of the two-stage actuators, the monitor closes the second control device, opens the third control device and opens the first control device to allow fluid flow from the lift chamber to the supplemental down chamber of each of the plurality of two-stage actuators.