A new type two-stage proportional electro-hydraulic regulator valve using piezoelectric ceramics is promoted to cancel the requirement of pressure sensor. The piezoelectric ceramics controls the openness of pilot valve. The pressure drops across the fixed damping hole in the pilot supplier

and the throttling orifice of the pilot valve change accordingly. Thus the output pressure of pilot stage is controlled by the piezoelectric actuator and it serves as the command pressure to the main stage. The detailed structure and working principle have been given

and mathematical models and simulation models have been established. The influences of structural parameters over static and dynamic performances have been studied by Simulink simulation. A tuning spring has been employed to extend the lower bound of output pressure to 0. A three-land main spool has been employed to reduce the flow force and increase the precision

which is verified by flow field analysis. Proper feedback damping hole has been chosen according to dynamic simulation to ensure dynamic performance of pressure reducing valve. The new type valve proved to be able to work as a pressure reducing vavle without empoying a pressure sensor

and it has good output pressure range

pressure precision and fast and steady dynamic response.