Modeling of a two-stage flapper-nozzle electrohydraulic servo valve exposed to acceleration

Abstract

The electrohydraulic valves are commonly used in the engineering applications because they cause the hydraulic systems to take the advantage of the electrical sensors and the electrical control commands. 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 acceleration especially the centrifugal acceleration in the aerospace applications. In a two stage flapper-nozzle electrohydraulic valve, the external acceleration changes the pressure of the fluid leaving the nozzles. Moreover it affects the flapper and the spool of the valve like an external force. Thus when the applied electrical current is zero, the acceleration diverts the spool of the valve from the equilibrium point. In this study the pilot pressures of the spool is modeled in the unsteady state condition. The effects of the acceleration on the elements of the two stage electrohydraulic valve are investigated. By simulation of the obtained model of the valve, the behavior of the system is analyzed.