Vibration characteristics of armature assembly in a torque motor with magnetic fluids

Attempting to suppress high frequency resonant vibrations of a hydraulic servo-valve torque motor, vibration characteristics of armature assembly in the torque motor with and without magnetic fluids are studied in this paper. The mathematical model of the resistance force that the magnetic fluids acts on the armature is established. The equivalent physical model of magnetic fluids which is taken as a spring and a damper, is studied according to the relationship between the resistance force and the squeezing displacement of the armature. The finite element models of armature assembly in torque motor with and without magnetic fluids are established. The FFT transformation of harmonic responses at the end of feedback rod with and without magnetic fluids are compared under the excitation of electromagnetic force. Both simulation and experimental studies have shown that high-frequency self-excited vibrations of a torque motor are suppressed significantly after adding the magnetic fluids into the working gaps. So it is of great benefit for the mechanism revealing of high frequency self-excited vibrations, and improving the overall performance of the servo-valves.