Dynamic analysis of a pilot-operated two-stage solenoid valve used in pneumatic system

A dynamic model was developed to study the dynamic characteristics of a pilot-operated two-stage solenoid valve used in pneumatic system. The dynamic model couples motion of the valve spindle with fluid in the system. While solving the system equations, vibration of the valve spindle, characteristics of the pressure-flow across valve orifices, pressure variation in valve chambers are taken into consideration. The model is validated by experimental results. With this model, the stability and dynamic response of the valve system for different operating conditions were discussed. The study identifies some critical parameters, which have significant effect on the dynamics of the system. A review of the obtained results indicate that the solenoid valve undergoes soft self-excited vibration, period-one hard self-excited vibration, period-two vibration, period-four vibration leading to stable working with the quasi-steadily increase in supply pressure or supply flow rate. Increasing in diameter of valve orifice db or decreasing in pre-compression of the valve spring z0, half-cone angle of the valve spindle α, diameter of valve orifice da would improve anti-disturbance capacity and increase stable region of the solenoid valve.