Numerical Investigation on Suppressing High Frequency Self-Excited Noises of Armature Assembly in a Torque Motor Using Ferrofluid

Abstract

Attempting to suppress high frequency self-excited noises of armature assembly, ferrofluid is added to the working clearances of torque motor. The mathematical model of resistance force of ferrofluid applied to armature is derived theoretically from parallel plate squeeze flow theory and ferrofluid constitutive model in which shear thickening and shear thinning effects are taken into account. Then the equivalent physical model of ferrofluid is established according to the resistance force, and, through analysis, it can be further simplified as viscous damping model. Finally, the suppressing effect introduced by ferrofluid on high frequency noises of armature assembly is verified by comparing the results of numerical simulation with ferrofluid and that without ferrofluid.

Analysis of the static and dynamic characteristics of the electro-hydraulic pressure servo valve of robot

“…The rotary direct drive electro-hydraulic pressure control servo valve (hereinafter referred to as RDDPV) 1 , 2 converts the rotary motion of torque motor into the linear motion of power spool via the eccentric drive mechanism, so as to change the throttling area ratio of the oil inlet and return windows, and output the corresponding load pressure; servo control is achieved via the closed-loop electrical feedback of motor position and output pressure. Klarecki analyzed the influence of electronic controller parameters on the dynamic characteristics of electro-hydraulic servo system 3 . With respect to related researches in China, Songjing et al 4 studied the vibration noise of torque motor, and in their work, the self-excited vibration of the torque motor is suppressed by adding magnetic fluid to the working clearance.…”