Effects of Structure Parameters on Abnormal Opening of Pilot-Operated Relief Valve Under Alternating Pressure.

Hydraulic vibration excitation has been widely regarded as a promising method of excitation because of its high power density and large output force. However, the alternating pressure in the hydraulic vibration exciter could cause the pilot-operated relief valve (PRV) to open abnormally, which presents a new challenge to the normal operation of the PRV. To determine the abnormal opening characteristics of the PRV under alternating pressure, the effects of structure parameters of the PRV (including diameters of orifices 1 and 2, volume of the pilot valve inlet, volume of the main valve spring chamber, area ratio of the main spool, and main spring pre-compression force and stiffness) on its abnormal opening displacement under alternating pressure were numerically investigated. The calculation results indicate that the abnormal opening of the PRV will be effectively decreased by appropriately increasing the diameter of orifice 1, decreasing the pilot valve inlet and main valve spring chamber volumes, and increasing the area ratio of the main spool and the main spring pre-compression force. The influence of the orifice 2 diameter on the abnormal opening of the PRV is dependent on the diameter range of orifice 1. The reasonable diameters of orifices 1 and 2 are in the range of 0.8-1.2 mm. The influence of the main valve spring chamber volume is more significant than the pilot valve inlet volume. The influence of the main spring stiffness is not significant.