Effect of the resonance suppression damping on the stability of a cartridge pilot-operated relief valve

The pilot-operated relief valve is a complex hydraulic component. The instability phenomenon during its application may cause some unexpected problems, such as poppet vibrations or pressure fluctuations, etc. Despite the abundant use of relief valves in pressure-control applications across various fields, there is a lack of quantitative stability criteria. This paper focuses on deriving the quantitative stability criteria of a cartridge pilot-operated relief valve. After establishing the detailed mathematical model of such a valve, the effects of the main parameters on its stability are analyzed through the Routh–Hurwitz stability criterion. The analysis results indicate that the unreasonable match between the chambers and the poppets may break the stability of the valve. However, limited to the internal space of the cartridge-type valve, some chambers are too small to match the minimum manufacturing mass of the poppets. To ensure the stability of the pilot-operated relief valve, a dynamic pressure feedback orifice is typically designed between the main stage and the pilot stage as a resonance suppression damping element. So that the contradiction between the stability criterion and the sensitive parameters will be resolved if the orifice is small enough. As a result, the stability of the pilot-operated relief valve may be considerably improved. Finally, simulations and measurements were utilized to verify the correctness of the predicted results.