SimHydraulics 1.6

Hydraulic System with Servo-Valve

The demo represents the 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 demo is represented with an ideal translational force source. These three blocks of a servo-valve are arranged as an individual subsystem in the Servo-Valve model. The Flapper/Armature subsystem is formed with three external connections: conserving mechanical translational port F, to which force input generated by a torque motor is connected; conserving mechanical translational port FSPR that provides a spring feedback between the main spool and the armature; and physical output port FPOS that exports instantaneous flapper deflection to be used in other subsystems. The spring feedback is simulated with the spring SPR_FBK and damper TD_FBK. The Flapper-Nozzle subsystem simulates a hydraulic part of the flapper-nozzle amplifier and consists of two nozzle models (Nozzle A and Nozzle B) and two fixed orifice blocks. The nozzles are simulated with the Variable Orifice blocks. Conserving hydraulic ports A and B correspond to hydraulic chambers on both sides of the main valve. Physical input port FPOS conveys flapper position computed in the Flapper/Armature subsystem. Port P is a hydraulic conserving port associated with the pressure supply connection. The Main Valve subsystem represents a servo-actuator acting on the main spool valve and four spool valve variable orifices. The actuator is simulated with the Translational Hydro- Mechanical Converter blocks acting against each other. The actuator drives a spool valve loaded with axial hydraulic forces on all four orifices, viscous friction TD1, and inertia M1. The values of hydraulic forces are determined in the Spool Orifice Hydraulic Force blocks connected in series with the Orifice with Variable Area Slot blocks. External ports of the Main Valve subsystem include hydraulic pressure supply and return ports P and T, actuator ports A and B, servo-actuator hydraulic ports A_S and B_S, and a mechanical translational port FSPR, through which the spool is connected to the feedback spring. The servo-valve controls a simple double-acting cylinder in an open-loop application.

Copyright 2008-2009 The MathWorks™, Inc.