Modeling And Analysis Of The Engine Valve Train Using Multi-body Dynamics

The valve train of the engine is used to exchange the charge in the cylinder, and mostly the valve trains used in the modern engines are the cam mechanisms. The studies of the valve trains are concentrated in two areas; on the one hand it is the research of the volumetric efficiency of the valve trains, and the design of the cam mechanisms to improve the volumetric efficiency of the valve trains; on the other hand is the study of the reliability of the valve train, such as the analysis of dynamics, vibration and noise, friction and fatigue damage. In this thesis, it focuses on the dynamic analysis of the valve train of the 165F diesel engine.Firstly the models of single degree of freedom and multiple degrees of freedom are developed for the dynamic analysis of the valve train, and the parameters in the models are determined by the formulas or the finite element method, and the differential equations in the models are solved using MATLAB. Two models are used to analyze the influence of the elasticity of the valve train on the valve movement, and in the model of multiple degrees of freedom the conditions such as the valve bounce are taken into account.At the same time it is discussed that multi-body dynamics of the valve train of the 165F diesel engine in the thesis. A multi-body dynamics model is developed in the ADAMS/Engine and then all the parts of it are made flexible. The rocker of the valve train is modeled and the modal analysis and stress analysis are made in ANSYS, the file of the results is exported to ADAMS to make the rocker flexible. The multi-body dynamics models with rigid parts and flexible parts are used to analyze the valve movement, the contact stress of the cam and the tappet, and the properties of the valve spring.Finally, using the software AVL/Tycon two cam profiles are designed and the comparative dynamics analysis is made about the models with the two cam profile and the cam profile of the 165F diesel engine.