The Research Of Rotarv Valve Control Hydraulic Vibration System

Electro-hydraulic fatigue test-beds are widely used in the fatigue test of the parts. The key element is the control valve. It is found that the control valve is the expensive servo slide valve, which leads to the small scale application of fatigue test bench. So the rotary valve is presented as a control valve in this paper. It has the characteristics of a simple structure, a high open-loop control precision, low costs, strong abilities to resist pollution. The rotary valves can control the frequency, amplitude and displacement offset of excited waves precisely. So it is significant to do the research of rotary valves. The research contents of this thesis are about t electro-hydraulic servo valve of rotational motion and its hydraulic vibration system. The main research content is as follows:(1)A new kind of rotary valve applied to the fatigue test bench is designed. And the effect of dynamic flow force to the movement of valve disk is also analyzed in detail. It is proposed to employ a proportional directional valve to adjust the wave offset of the piston rod in parallel with the rotary valve. Then the mathematical model of rotary valve controlling hydraulic vibration system is constituted with the adjusting regulator of displacement offset. And it is easy to establish the numerical simulation model of the system in the Matlab/Simulink according to the mathematical model. The simulation verifies the capacity of rotary valve controlling hydraulic vibration system. At the same time some control characteristics are obtained.(2)The control system consists of three independent control units in the rotary valve electro-hydraulic vibrator:The control unit of rotary motor adjusting vibration frequency, the control unit of linear motor regulating the excitation amplitude values, the control unit of proportional directional valve adjusting displacement offset. Because of the coupling control of vibration frequency, excitation amplitude values and displacement offset, the control strategy of half closed loop based on displacement characteristic value is proposed.(4) The rotary valve control hydraulic vibration system test bench is built. The displacement waves are analyzed under no-load and load conditions. The experiment demonstrates it is practicable to adjust the displacement waves by the half closed loop controller. The controllable frequency and amplitude of displacement waves are obtained. And the adjusting displacement waves are unbiased by adjusting the proportional directional valve. It verifies the validity of the simulation model and the feasibility of the half closed loop controller.