DYNAMIC CHARACTERISTICS OF A DIRECT-PRESSURE SENSING WATER HYDRAULIC RELIEF VALUE

Abstract

This paper deals with dynamic characteristics of a direct-pressure sensing water hydraulic relief valve. Four hydrostatic bearings support the main valve to reduce hysteresis of static characteristics of the valve. Hence, Coulomb friction acting on the main valve is not available as damping force. A damping orifice is inserted between the main- and pilot valves to get a damping force for the main valve, while the orifice diameter affects on stability of the main valve. In addition, the motion of the pilot valve has large effects on the response of the relief valve itself. To show these influences, we compute the response to a step input of relief flowrate with the MATLAB/Simulink. The results show that the design parameters affecting the stability are followings: (1) the damping orifice diameter, (2) spring stiffness for the pilot valve, and (3) volume of a chamber between the damping orifice and the pilot valve.