Analysis of Rotary Direct Drive Electro-hydraulic Pressure Control Servo Valve

A rotary direct drive electro-hydraulic pressure control servo valve(RDDPV) is proposed and designed. This new-type servo valve converts the rotary motion of torque motor into linear motion of spool by the eccentric drive mechanism, then the throttle area ratio of the inlet and outlet is changed and corresponding pressure is output, and the servo control is achieved by the electrical feedback loop of the motor position and output pressure. The nonlinear mathematical model of RDDPV is established to study the influence of structure parameters, especially eccentric mechanism parameters, on the static and dynamic characteristics of the servo valve,and the main structural parameters of the valve were determined. The RDDPV prototype was manufactured and its basic characteristics were tested on test bed. The results showed that the valve had high dynamic and static performance, and it could be applied to those pressure servo control systems that required high performance in stability, accuracy and speed, such as the anti-skid brake system of airplane.