Dynamic characteristics research of direct acting pressure relief valves through frequency response methods

The pressure relief valve is a basic component in every hydraulic system. Its function is to limit maximal pressure in the system independently of the flow across the valve. Many authors have investigated the characteristics of this type of valves and different mathematical models have been obtained which described their characteristics. In this paper an attempt has been done, with contemporary mathematical approach, to determine the mathematical model of a specified pressure relief valve including all features of the valve such as compressible volume in front of the inlet port of the valve, pipeline with oil at the outlet port of the valve and hydrodynamic force. In this paper a frequency response method is applied for dynamic characteristics investigation of the direct acting pressure relief valve. From the frequency characteristics it can be determined the frequency range for stable operation of the valve. It is shown that at high frequency of operation the valve is working as a throttle with fixed orifice. It has been shown how the compressible oil in front of the valve can occur unstable operation of the valve