Effect of key structures and parameters on dynamic characteristics of three-stage jet-pipe servo valve

Abstract

The traditional two-stage electro-hydraulic servo valve cannot meet the needs of production equipment with large flow rate and wide frequency bandwidth. The structure and working principle of the three-stage jet-pipe electro-hydraulic servo valve are described. As the structure of the three-stage valve is complex and many factors influence dynamic characteristics, the main objective of this study is to establish a mathematical model and investigate those factors. In order to advance the local phase, a proportional–derivative correction link is added to the closed-loop transfer function of the three-stage valve. By simulations, the step response curve and open-loop Bode curve are obtained for analysis in the frequency domain and the time domain. The influences of main factors such as flow gain, pressure gain, main spool area, and feedback-rod rigidity on the dynamic response of the valve are analyzed in the time domain. A three-dimensional model of the armature–feedback-rod component is established and is simulated using the Workbench finite-element analysis software. The influences of various structural parameters are analyzed, especially those of the rod area, section shape, length, and material on the feedback rod rigidity.