Modelling and Simulation of the Transient Performance of a Direct Operated Pressure Relief Valve

The dynamic characteristics determine variations of the inlet pressure in front of the valve in function of the flow through the valve in the time. In any hydraulic system, the valve is connected at least by a pipe at the outlet, and at its inlet there is some volume of compressible oil which influences the quality of the transient process. When switching the directional control valve in the hydraulic system with direct- operated pressure relief valves, a transient process occurs in which it is possible for the pressure to reach values many times higher than the set value. This causes the system to be overloaded with undesirable consequences. This paper examines experimentally and theoretically the transients in hydraulic systems with these valves. From the experimental static characteristics, the coefficient of hydrodynamic force acting on the valve poppet is determined