Electrically actuated variable pressure control system

Abstract

An electrically-actuated variable pressure control system for use with flow-controlled liquid application systems. Direct acting solenoid valves are pulsed at varying frequencies and duty cycles to change the resistance to flow encountered by the flow-controlled liquid application system. This pulsing solenoid valve technique preserves a high degree of accuracy and uniformity through a wide range of pressure control. This wide range of pressure control indirectly allows the flow-controlled liquid application system to operate over a wider range of flow control, yielding indirect benefits to performance and productivity. When the solenoid valves are attached to pressure-atomization spray nozzles, control over spray pattern and droplet size is further achieved.

1 . An agricultural spraying system, comprising: 
 a valve including a nozzle and an actuator assembly, the nozzle having an orifice defined therethrough, the actuator assembly being configured to control an emission of an agrochemical from the orifice;    a pipe connected to the valve and configured to deliver the agrochemical thereto;    a pressure sensor connected to the pipe for sensing a pressure in the pipe; and    a pressure controller in communication with the pressure sensor, the pressure controller being configured to change a flow resistance based on the sensed pressure to maintain a predetermined pressure in the pipe for the emission of the agrochemical from the orifice.    
   
   
       2 . The agricultural spraying system as in  claim 1 , wherein the nozzle is a pressure-atomization spray nozzle configured to produce a desired droplet size spectra and an agrochemical spray pattern.  
   
   
       3 . The agricultural spraying system as in  claim 1 , wherein the actuator assembly includes a reciprocating solenoid actuator configured to move relative to the orifice when a voltage is applied to the reciprocating solenoid actuator.  
   
   
       4 . The agricultural spraying system as in  claim 1 , wherein the actuator assembly includes a coil, a guide, and a plunger, the coil being disposed about the guide, the plunger being interposed between the guide and the orifice and being configured to move relative to the orifice when a voltage is applied to the coil.  
   
   
       5 . The agricultural spraying system as in  claim 1 , further comprising means for controlling the actuator assembly, the actuator assembly defining an open position and a closed position.  
   
   
       6 . The agricultural spraying system as in  claim 5 , wherein the means for controlling is a square wave generator being configured to apply a voltage to the actuator assembly to move the actuator assembly from the closed position to the open position for the emission of the agrochemical from the orifice.  
   
   
       7 . The agricultural spraying system as in  claim 5 , wherein the square wave generator is configured to modulate a square wave frequency and a duty cycle to change the flow resistance for the emission of the agrochemical from the orifice.  
   
   
       8 . The agricultural spraying system as in  claim 7 , wherein the square wave generator is disposed in the pressure controller.  
   
   
       9 . The agricultural spraying system as in  claim 1 , further comprising an agrochemical tank for holding the agrochemical, the agrochemical tank connected to the pipe.  
   
   
       10 . The agricultural spraying system as in  claim 1 , further comprising a pump for pumping the agrochemical through the pipe.  
   
   
       11 . The agricultural spraying system as in  claim 10 , wherein the pump is one of a positive displacement pump and a centrifugal pump.  
   
   
       12 . The agricultural spraying system as in  claim 11 , further comprising a wheel and a piston, the piston connected to the wheel and to the positive displacement pump, the piston being configured to reciprocate the positive displacement pump as the wheel turns.  
   
   
       13 . The agricultural spraying system as in  claim 11 , further comprising a plurality of valves, each of the valves being configured for independent operation, or at least two of the valves being configured as a group to stop the emission of the agrochemical from the group.  
   
   
       14 . An agricultural spraying system, comprising: 
 an actuating valve including a nozzle and an actuator assembly, the nozzle having an orifice defined therethrough, the actuator assembly being configured to control an emission of an agrochemical from the orifice;    a pipe connected to the actuating valve and configured to deliver the agrochemical thereto;    a regulating valve connected to the pipe for regulating a predetermined flow rate of the agrochemical through the pipe;    a flow controller in communication with the regulating valve to control the predetermined flow rate;    a pressure sensor connected to the pipe for sensing a pressure in the pipe and    a pressure controller in communication with the pressure sensor, the pressure controller being configured to change a flow resistance based on the sensed pressure to maintain a predetermined pressure in the pipe for the emission of the agrochemical from the orifice, the predetermined pressure dictated by the flow resistance.    
   
   
       15 . The agricultural spraying system as in  claim 14 , further comprising a square wave generator being configured to apply a voltage to the actuator assembly to move the actuator assembly from a closed position to an open position for the emission of the agrochemical from the orifice.  
   
   
       16 . The agricultural spraying system as in  claim 15 , wherein the square wave generator is configured to modulate a square wave frequency and a duty cycle to change the flow resistance for the emission of the agrochemical from the orifice.  
   
   
       17 . The agricultural spraying system as in  claim 14 , wherein the pressure controller determines the predetermined flow resistance based on a system speed, a system condition, an application rate, a target area size, a geographic location, a field position, a weather phenomenon and combinations thereof.  
   
   
       18 . The agricultural spraying system as in  claim 14 , wherein the pressure controller determines the predetermined pressure and maintains the predetermined pressure based on a system speed, a system condition, an application rate, a target area size, a geographic location, a field position, a weather phenomenon and combinations thereof.  
   
   
       19 . The agricultural spraying system as in  claim 14 , further comprising a controller configured to set the predetermined resistance to flow.  
   
   
       20 . A method of controlling pressure and flow for application of an agrochemical from an agricultural spraying system, the method comprising: 
 pumping an agrochemical from a tank through a pipe to an actuating valve including a nozzle and an actuator assembly, the nozzle having an orifice defined therethrough, the actuator assembly being configured to control an emission of the agrochemical from the orifice;    regulating a predetermined flow rate of the agrochemical through the pipe by a regulating valve connected to the pipe;    controlling the predetermined flow rate with a flow controller in communication with the regulating valve;    sensing a pressure in the pipe using a pressure sensor connected to the pipe; and    changing a flow resistance with a pressure controller based on the sensed pressure to maintain a predetermined pressure in the pipe, the pressure controller in communication with the pressure sensor, the pressure controller being configured to for the emission of the agrochemical from the orifice, the predetermined pressure dictated by the flow resistance.    
   
   
       21 . The method as in  claim 20 , further comprising changing the flow rate to change the pressure.  
   
   
       22 . The method as in  claim 20 , further comprising assessing correctness of the flow rate with the flow controller.  
   
   
       23 . The method as in  claim 20 , further comprising opening the regulating valve when the flow rate is too low.  
   
   
       24 . The method as in  claim 20 , further comprising closing the regulating valve when the flow rate is too high.  
   
   
       25 . The method as in  claim 20 , further comprising assessing correctness of the sensed pressure with the pressure sensor.  
   
   
       26 . The method as in  claim 20 , further comprising increasing flow resistance when the sensed pressure is too low.  
   
   
       27 . The method as in  claim 26 , wherein decreasing a duty cycle of a square wave increases flow resistance.  
   
   
       28 . The method as in  claim 20 , further comprising decreasing flow resistance when the sensed pressure is too high.  
   
   
       29 . The method as in  claim 26 , wherein increasing a duty cycle of a square wave decreases flow resistance.