Dynamic response of a hydraulic servo-valve torque motor with magnetic fluids

As magnetic fluids (MF) show higher saturation magnetization and larger viscosity when exposed to a magnetic field, large damping forces or resistance will be exerted on the armature of a hydraulic servo-valve torque motor by magnetic fluids if they are filled into the working gaps of the motor. This paper focuses on the application of magnetic fluids in a hydraulic servo-valve torque motor, especially the influence of magnetic fluids on the dynamic response of the motor. After introducing the working principle of the torque motor with magnetic fluids, the dynamic mathematical models of the torque motor and magnetic fluids are presented. The torque working on the armature introduced by magnetic fluids is analyzed. In order to study the influence of magnetic fluids, dynamic response of the torque motor is simulated and tested when magnetic fluids are applied or not in the motor. Simulation and experimental results show an obvious influence of magnetic fluids on the dynamic response of the hydraulic servo-valve torque motor.