Servo-Valve Controlling Hydraulic Actuator

Warning: This example uses the hydraulic domain, which will be removed in a future release. Find an equivalent example model that uses the isothermal liquid domain here: Servo Valve with Custom Fidelity. To convert models to the isothermal liquid domain, use the hydraulicToIsothermalLiquid tool.

This example shows a model of a two-stage servo-valve with a 4-way, 3-position spool valve in the power stage and a flapper-nozzle amplifier in the pilot stage. The flapper is connected to the armature of a torque motor, which in the example is represented with an ideal translational force source. The servo-valve shown in the example is equipped with the spring feedback between the flapper and the spool of the main valve. To investigate the behavior of such a valve, axial hydraulic forces on all four spool orifices are accounted for in the model by using Spool Orifice Hydraulic Force blocks. The servo-valve controls a simple double-acting cylinder in an open-loop application.

Model

Servovalve Subsystem

Main Valve Subsystem

Orifice AT Subsystem

Simulation Results from Simscape Logging

The plots below show the pressures in the cylinder and the velocity of the spool in the pilot stage. The effect of the pilot stage spool oscillations are visible in the cylinder pressures.

The plots below show the flow rates in the valve and the position of the piston.