The Design And Performance Study Of Pilot Valve Based On Permanent Magnet Spring Pilot Operated Relief Valve

In hydraulic systems,the relief valve is one of the most important pressure control components,primarily for constant pressure relief and safety protection of the system.The pressure regulation of the pilot type relief valve is mainly realized by the mechanical spring in the pilot valve.Due to the inherent properties of the material,the traditional mechanical spring often has failure modes such as hardening,fatigue fracture and slack,which causes the pressure regulation of the relief valve to fluctuate.Reduced pressure accuracy,large pressure loss,etc.With the development of magnetic material technology,permanent magnet springs have been widely used.Compared with mechanical springs,permanent magnet springs have good force-displacement performance,simple structure,and no fatigue fracture,which replaces traditional mechanical springs to improve pilot type.The pressure relief of the relief valve reduces pressure loss,reduces valve body noise and vibration.This paper describes the classification and research status of the relief valve,and summarizes the classification of the spring and the research status of the permanent magnet spring.The classification of permanent magnet materials is introduced.The magnetic properties of rare earth NdFeB permanent magnet materials are analyzed,and the magnetic theory is applied to lay the foundation for the design of permanent magnet springs.According to the parameters of the pilot valve of the pilot type overflow valve and the design principle of the magnetic circuit,two permanent magnet springs with repulsive force and attractive force are designed by using the principle of "the same name magnetic pole repels and the same name magnetic pole attracts".The magnetic material of different grades of magnetic material and permanent magnet spring was simulated by Ansoft Maxwell software,and the magnetic material of the permanent magnet spring and the repulsive permanent magnet spring model were finally determined.The internal flow field of the pilot valve of the designed permanentmagnet spring pilot relief valve is simulated by CFD software.The simulation results show that the pilot valve structure is reasonable,and the flow field pressure drop in the pilot valve meets the requirements of the main spool opening pressure.The dynamic pressure at the junction of the pilot valve and the main valve is small,and the connection stability is high,meeting the design requirements.Finally,the differential pressure-flow and pressure-flow characteristics of the mechanical spring and the permanent magnet spring pilot type relief valve are compared.The results show that the differential pressure-flow characteristic of the permanent magnet spring pilot type relief valve is better,that is,the pressure loss is small.The performance is excellent and the structure design is reasonable;the slope of the pressure-flow characteristic curve of the permanent magnet spring pilot type relief valve is small,that is,the pressure at the inlet changes little with the fluctuation of the flow rate,the constant pressure precision is high,and the vibration generated by the pressure change The noise is smaller.