Influence of Magnetic Reluctances of Magnetic Elements on Servo Valve Torque Motors

• Published in: Chinese journal of mechanical engineering Vol. 29; no. 1; pp. 136 - 144
• Main Authors: Liu, Changhai, Jiang, Hongzhou
• Format: Journal Article
• Language: English
• Published: Beijing Chinese Mechanical Engineering Society 2016; School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
• Subjects: Electrical Machines and Networks; Electronics and Microelectronics; Engineering; Engineering Thermodynamics; Experiment; Heat and Mass Transfer; Instrumentation; Machines; Manufacturing; Mechanical Engineering; Power Electronics; Processes; Simulation and Calculation; Theoretical and Applied Mechanics; 力矩电机; 力矩马达; 数学模型; 气隙磁通密度; 电液伺服阀; 磁性元件; 磁阻; 解析表达式; servo valve torque motor; magnetic spring stiffness; magnetic reluctance; electromagnetic torque constant
• ISSN: 1000-9345; 2192-8258
• DOI: 10.3901/CJME.2015.1204.142

The current research of electro-hydraulic servo valves mainly focuses on the vibration, pressure oscillating and source of noise. Unfortunately, literatures relating to the study of the influence of the magnetic reluctances of the magnetic elements are rarely available. This paper aims to analyze the influence of the magnetic reluctances of the magnetic elements on torque motor. Considering these magnetic reluctances ignored in previous literatures, a new mathematical model of servo valve torque motor is developed and proposed based on the fundamental laws of electromagnetism. By using this new mathematical model and the previous models, electromagnetic torque constant and magnetic spring stiffness are evaluated for a given set of torque motor parameters. A computer simulation by using AMESim software is also performed for the same set of torque motor parameters to verify the proposed model. The theoretical results of electromagnetic torque constant and magnetic spring stiffness evaluated by the proposed model render closer agreement with the simulation results than those evaluated by the previous models. In addition, an experimental measurement of the magnetic flux densities in the air-gaps is carried out by using SFL218 servo valve torque motor. Compared with the theoretical results of the magnetic flux densities in the air-gaps evaluated by the previous models, the theoretical results evaluated by the proposed model also show better agreement with the experimental data. The proposed model shows the influence of the magnetic reluctances of the magnetic elements on the servo valve torque motor, and offers modified and analytical expressions to electromagnetic torque constant and magnetic spring stiffness. These modified and analytical expressions could provide guidance more accurately for a linear control design approach and sensitivity analysis on electro-hydraulic servo valves than the previous expressions.