Analysis On Dynamics And Vibration Characteristics Of Valve Train Of Vehicle Engine

The valve train is an important part of an engine, which influences the economy, emission,NVH and reliability performance directly. Aiming at the LJ750 engine made by the Luoyang north industry group, the cam profile design, dynamics, and vibration of the valve train is researched; the force between the cam—tappet pairs and between valve–valve seat are discussed as well.First, the paper summarizes the research production of valve train dynamics and vibration in and out abroad, which is helpful in identifying the key problems. Secondly, special attention has been focused on the optimum design of cam profile, and approach of compound shape has been applied to the solution of optimum cam profile. Influence of the variety of power of the cam profile on the characteristics of cam movement has been discussed as well. Single mass model, two-mass model and multi-mass model of vehicle engine valve train have been established, which is the basis of analyzing dynamics and vibration of valve train. Particular attention was focused on the deduction of mathematic model of the valve spring, and the influence on the force exerted on the valve train made by the change of the valve stiffness, the change of the cam speed, and the change of the valve lash. The characteristics of the vibration are also analyzed on the biases of valve train dynamics. Suitable suggestions on the chosen of the stiffness of the valve train and the valve spring has also been put forward. Collision between valve face and valve seat has been simulated in the software environment of ANSYS/LS-DYNA.