Harmonic response characteristics of a hydraulic servo-valve torque motor

ZHANG Liang， PENG Jing-hui， LI Song-jing
（Department of Fluid Control and Automation， Harbin Institute of Technology， Harbin 150001， China）

Abstract： Aiming at the mechanism of self-excited noise in servo valves，vibration characteristics of servo valve torque motors was studied. The structure and working principle of a double-nozzle-flapper servo valve torque motor was introduced. By using the finite element analysis method and model analysis，the corresponding natural vibration frequencies of the first seven-order vibration modes were calculated. The harmonic response curves under the electromagnetic force were given. The results indicate that the armature and feedback rod is the key parts which may cause vibration in the servo-valve. The vibration of them in the working plane makes the greatest impact on the performance of the servo valve. The resonant peak of the armature and nozzle flapper group is concentrated in the low frequency and a calculation method of the amplitude is given by the harmonic response analysis. Then a theory reference for improving the performance and the optimization of the structure of the servo valve is presented.
Key words： double-nozzle-flapper；servo valve； torque motor； vibration characteristics； harmonic response characteristics； finite element