Control Methods Research On An Electro-magnetic Fully Variable Valvetrain With Seating Buffer

Electromagnetic fully variable valve train(EMVT)technology promises to improve fuel economy and optimize engine performance,but the problem of valve seating impact still exists.In order to solve this problem,a novel EMVT equipped with a magnetorheological buffer(EMVT with MR buffer)is proposed to suppress the valve seating impact,which has the advantages of fast response and continuous adjustable damping characteristics.This paper focuses on the control method of EMVT with MR buffer,so the following work is carried out:(1)The structure scheme of EMVT with MR buffer is introduced,The structure composition and control difficulties of the valve system is analyzed.The paper introduces the working principle and important parameter measurement of EMVT with MR buffer.(2)The mathematical model of multi physical field and multi component coupling of electromagnetic valve with cushion and seat is established.The valve motion model,electromagnetic linear actuator model and magnetorheological buffer model are constructed.The sub model verification and parameter identification are completed through experiments.The high-order nonlinear model is established by Matlab/Simulink.(3)For the transition process and seating process of valve movement,the valve control strategy based on subsection control method is studied.The transition process needs to meet the needs of rapid response.The inverse system method is used to establish the pseudo linear system,and the displacement control is carried out by state feedback.The landing process needs to meet the needs of soft landing.Jacobian linearization is carried out at the landing point.The internal and external double-layer controllers are used.(4)The control system test platform is built.In the transition process,the variable parameter tests of valve opening time,lift and opening duration are completed.The maximum displacement error is 0.05 mm,and the transition time is about 4ms.The correctness of the inverse system algorithm is verified.In the process of seating,when the maximum lift of the valve is 8mm,the seating velocity is reduced from 0.58m/s to 0.14m/s,and the seating velocity decreases by 75.8% the rebound height can be reduced from 0.25 mm to 0.05 mm,and the rebound height decreases by 80%.