MODELING THE EFFECTS OF THE EXTERNAL ACCELERATION ON THE TWO STAGE FLAPPER- NOZZLE SERVO ELECTROHYDRAULIC VALVES

Original Research Paper Received 21 June 2015 Accepted 16 August 2015 Available Online 30 September 2015 The electrohydraulic valves are commonly used in the engineering applications. These valves, as the medium elements, prepare the hydraulic systems for the electrical control applications. For the precise performance of these valves, disturbances in the valve elements dynamics will disturb the control process of the system. The electrohydraulic servo valves are greatly affected by the external acceleration, for instance in the aerospace applications. In two stage flappernozzle electrohydraulic valve, the external acceleration changes the pressure of the fluid leaving the nozzles and affects the flapper and spool of the valve like virtual force. Thus, when the applied current is zero, the acceleration diverts the spool of the valve from the equilibrium point, and unwanted performance in the valve occurs. In this study the pilot pressures of the spool are modeled in unsteady state condition. The effects of the acceleration on the flapper and the spool of the two stage electrohydraulic valve are investigated. At the end, the obtained model is verified by use of the experimental data.