Modeling for finding armature assembly moment of inertia in jet pipe servo valve torque motor

摘要

Jet pipe electro-hydraulic servo valve is the heart of feedback control system, its performance plays an important role in establishing the properties of the system. Dynamic characteristics of the jet pipe servo valve depend on many parameters such as the stiffness of flexure tube and feedback spring or the moment of inertia of torque motor. The research results show that the stiffness of armature assembly and feedback spring are the key parts which can be directly related to the geometric and material parameters of torque motor. A suitable stiffness of the elastic system is necessary because a too low stiffness results in unstable equilibrium while a high stiffness requires a high electric input current. It is required the best stiffness of the flexure tube and the overall system for improving dynamic characteristics. A finite element method analysis is used in mathematical model for finding stiffness of the elastic system, moreover, the effect of amplitude bandwidth on the dynamic characteristics is developed, too. In order to improve the dynamic response bandwidth of two-stage jet pipe electro-hydraulic servo valve, optimal design for the moment of inertia of torque motor is investigated in this paper. The approximate range of the moment of inertia, J_(a) , is found and the proper cause-effect relationship between the bandwidth and, J_(a) , is revealed as well.