Simulation And Research On Fully Variable Mechanical Action Valve Lift Control System

With the development of modern high-tech, energy-saving, efficiency, low emissions has been the new requirements to automobile engine; "energy saving - high efficiency - environment-friendly" has been an integration of the subject which needs technological development and comprehensive research. Fixed limit of valve timing becomes more and more unsuited to the requirement of energy saving and emission requirements. To this end, variable valve actuation (VVA) technology has become a key direction of the automotive engine research.Variable valve actuation technology, including continuously variable valve timing technology and continuously variable valve lift technology, which can chose different levels of gas phase and valve lift according to the different conditions of the engine to meet the requirements of engine at high speed and low speed, heavy load with small load. so it can improve the power, economy and idle stability of the engine comprehensively. Specifically, when there's part of load, the variable valve actuation technology control the gas mixture in the cylinder by turning off the intake valve early or reducing intake valve lift. in this way, it makes throttle-free load control mode come true, and reduce the losses of pumping, improves the fuel economy of gasoline engine. Moreover, the smaller valve lift improves the flow speed, so it can improve the mixture of fuel and air when the gasoline engine is under conditions of low-speed and low load, thereby improving the process of combustion.This article mainly research the fully variable mechanical action valve lift control system, gives a brief analysis of the continuously variable valve timing (VVT) system, continuously variable valve lift (VVL) system, and mapping and curve fitting with related mechanical parts of the variable mechanical action valve lift control system (Valvetronic) of the BMW engine; created 3D solid model with geometric modeling software CATIA and got the valve lift curve under different eccentric shaft corner by CATIA kinematic simulation analysis module; derivation a kinematics mathematical model of variable valve actuation, calculated valve lift curve under different eccentric shaft angle with Matlab software. The results of mathematical model of valve train kinematics simulation are consistent with the CATIA geometric model. In this way ,this article confirms the correctness of the mathematical model and provides a theoretical basis for the design of continuously variable valve.