Variable Load Sensing Electro-Proportional Valve with Torque, Power and Anti-Stall Control for Variable Displacement Axial Piston Pumps

An innovative electro-hydraulic implementation of variable load sensing control for variable displacement axial piston pumps is presented, in which a standard hydraulic load sensing compensator is equipped with an additional proportional solenoid, providing an extra force on the spool, to override the compensator's working point. An embedded electronic control unit acquires the relevant physical quantities by means of a limited set of sensors installed in the system and provides the output current to set the required overriding force, to implement the additional controls on the pump, viz. torque, power, anti-stall (speed) and variable load sensing. The actuation of pump displacement control through the hydraulic compensator provides fast dynamics and stability to the electronic control schemes, allows retrofitting to standard devices and, since the standard hydraulic load sensing control is active when the solenoid is not energized, makes the system workable also in case of failure of the ECU output stage.