Servovalve-Controlled Pneumatic Suspensions

Abstract

A linear analytical model of a ground-vehicle suspension system employing a pneumatic isolator and a three-way servovalve is developed. Damping is provided by connecting the pneumatic spring to a constant-volume surge tank through capillary resistances. Non-dimensional dynamic equations for the valve-controlled, self-damped, pneumatic isolator are derived and the effects of various feedback and feedforward controls on the performance of the closed-loop system are pointed out. Experiments are conducted to verify the validity of the assumptions made in deriving the absolute and relative displacement transmissibilities and the vehicle model is simulated on an analogue computer. It is shown that a servovalve-controlled pneumatic suspension system not only considerably reduces the body transmissibility at very low frequencies, but is also capable of very good isolation throughout the broad frequency range.