Study On The Vibration Property Of Hydraulic Poppet Valve

As an important and fundamental component in hydraulic transmission and control system, Hydraulic poppet valve is widely used in hydraulic system for the reason of resisting contamination capacity, good sealing property and simple structure. However, The problem of vibration, cavitation and noise in the poppet valve affect its applications severely. As the development of hydraulic technology, It's proposed more accurate requirements for hydraulic components. Therefore, the vibration, static and cavitation properties of poppet valve are concerned broadly in the field of engineering and industry.In this paper, the major work is using CFD software to modeling and simulating folw field in the poppet valve, The main point is to research the reason that causes vibration of poppet valve and how to decrease valve vibration, And also cavitation under different valve structures is included in the simulation, from the perspective of fluid visualization, the location and intensity of cavitation with different structures are analyzed.This thesis consists of five parts:(1) Designing the hexahedral mesh model of simplification poppet valve to be parameter in STAR-CD, utilizing ANSYS CFX to make static and transient simulation. The effects of cone "A" and spool circumference diameter "B" on the poppet valve's static and transient properties are analyzed primarily, and also the effects of port chamfer on poppet valve's properties is researched;(2) According to the spool dynamics equation and flowratio equation, the dynamic mathematical model is set up, and the model is put up in SIMULINK, via analysis of mathematical model, It's obtained that the magnitude and direction of steady-state flow force has great effect on transient property of poppet valve;(3) The CFD model is set up for the poppet valve vibrating strongly in practice by HITACHI, the steady calculation is implemented in different valve port opening, Combining the mathematical model and pressure field structure, It's indicated the reason why the poppet valve tends to vibrate from the point of structure, the original poppet valve is modified in structure, and its flow field is calculated also, finally, transient simulations in the case of inlet pressure step signal are made for both original structure and modified structure, the transient result verifies that the validation of theoretical analysis about the vibration reason.(4) The structural optimization is conducted for the original poppet valve of HITACHI, the effect of different structural parameters on poppet valve vibration property is researched, It's found that except for steady-state flow force, an slender annular crack throttling in the top of the cone may also causes poppet valve vibration, the transient simulation result shows the validation of research for vibration element;(5) The CFD cavitation simulation is carried out for both original structure and optimal structures, The cavitation model is included in flow field simulation to research the cavitation property of different valve structures, the simulation results and the pressure distribution profile on spool surface show:The original structural poppet valve tends to vibrate, however, it's not tends to generate cavitation phenomenon, on the other hand, the modified and optimal structures can decrease vibration indeed, but cavitation phenomenon is more prone to emerge in such structures, Cavitation and vibration consist of a contradiction that exist in poppet valve.