Research On Static And Dynamic Characteristics Of Proportional Solenoid Valves Used In Variable Valve Timing System Of Engine

Variable valve timing technology is one of the technical means that can achieve energy-saving and emission-reduction..The proportional solenoid valve is one of its core components.The performance of the solenoid valve directly affects the operating characteristics of the variable valve timing system.Therefore,it is necessary to develop the research of proportional solenoid valve.Through the research of proportional solenoid valve,the influence of various parameters of solenoid valve on its static and dynamic performance is obtained,which provides theoretical guidance for optimal design of proportional solenoid valve.In this paper,the static displacement-force characteristics and dynamic response characteristics of a proportional solenoid valve for a variable valve timing system are studied.The main research contents are as follows:The static and transient magnetic field simulation model of the proportional solenoid valve was established by Ansoft maxwell software.Based on the verification requirements of the simulation model,a static and dynamic characteristics test platform was built,and the simulation data was compared with the test data.It was found that the maximum deviation of the static displacement-force characteristics was 5.3%.The maximum deviation of the open response time is 4%,which verifies the correctness of the simulation model.The static simulation model was used to analyze the influence of the core material,core structure,guide bush thickness,pole shoe structure,radial clearance and coil position of the proportional solenoid valve on the static displacement-force characteristics of the solenoid valve.The results show that the core material,core length and thickness,pot width,pot height,ramp height,pot angle,and radial clearance are significant factors affecting the static displacement-force characteristics of the solenoid valve.The thickness of the guide bush,the chamfer and fillet of the core,the chamfer and fillet of the pole shoe,and the position of the coil are the secondary factors affecting the static displacement-force characteristics of the solenoid valve.Based on the robust design concept of Taguchi method,the structural parameters of the solenoid valve were optimized.The significant factors affecting the electromagnetic force of the proportional solenoid valve were as follows: pot height,core thickness,slope height,pot width.The significant factors affecting the horizontality of displacement-force characteristics of proportional solenoid valves are: iron core length,core thickness.Compared with the original displacement-force curve,the electromagnetic force is compensated when the working air gap is large;however,when the current is small,the electromagnetic force is reduced.When the current is large,the electromagnetic force is closer to the target valve;the level of displacement-force characteristics is better within the entire operating plane.The influence of driving voltage,spring stiffness,spring preload,mass of moving parts and resistance on the opening response time of proportional solenoid valve is analyzed by using the dynamic simulation model.It is concluded that the driving force voltage is the most important factor affecting the contact time.The secondary factors are spring preload,resistance,mass of moving parts,and the spring stiffness has almost no effect on the pull-to-touch time.The most important factor affecting the opening time of the solenoid valve is the driving voltage.The secondary factors are the coil resistance,the spring stiffness,the spring preload,and the least influence of mass of moving parts.Through the experimental design concept,the drive voltage,coil resistance,spring preload,spring stiffness and mass of moving parts are taken as independent variables,and the opening response time is used as the response variable,and an experimental scheme is developed by MODDE software.The response time result obtained by Ansoft was imported into MODDE.The correlation analysis was carried out by partial least squares method.The correlation between the influencing factors in all working planes and the opening response time of the solenoid valve was obtained.The results show that the correlation between the first factor and the opening response time is the driving voltage,resistance,and spring stiffness.The absolute value of the correlation coefficient decreases with the increase of the duty cycle of each operating point.Increased with the increase of the coefficient of friction at each operating point.The secondary factors formed by the self-interaction of the parameters and the correlation of the solenoid valve have different regularity from the primary factor.