Cam Profile Design And Dynamics Research Of Engine Valve Train

Valve Train is an important component of the engine. The engine’s power performance, emission performance, fuel economy and reliability have close ties with it. Cam profile is the hard core of the valve train. So the cam design is crucial to the valve train’s performance.In this paper, the kinematics and dynamics model on the valve train with hydraulic tappet of engine are built up with AVL EXCITE Timing Drive, which is the valve train dedicated software. The cam lines of the original model is fitted,via computer simulation optimization with kinematic model. The dynamic model includes a single valve system valve train dynamic model and overall valve train dynamic model. The hydraulic tappet performance, dynamics correction of the cam profile, dynamic characteristics between the transmission chain of the valve train and camshaft vibration are analyzed, via the kinetic model. The main contents of the study are as follows:1) The cam profile data of the original models is mapped by the coordinate measuring instrument. The data is imported UG and then by using the initial fitting adjustment of the spline curve, the usable original AVL EXCITE Timing Drive cam lines date file is obtained. 2) The kinematics model on the valve train of the engine is built up with AVL EXCITE Timing Drive. And then the original cam profile data is imported the model.And the original cam profile data is optimized design by the Cam design module in the software. The optimized cam profile can reduce the valve jerk, improve the lubrication between the cam and the tappet and ensure the normal work of the hydraulic tappet.3) The single valve system valve train dynamic model is built up with AVL EXCITE Timing Drive. Research and analysis on the spring characteristic and crash of valve have been made according to the dynamic characteristics of hydraulic lifter as a result of single valve system distribution mechanism dynamics model influencing the distribution device when engine is in medium speed and high speed.4) The overall valve train dynamic model is built up with AVL EXCITE Timing Drive. The model is based on single valve system valve train dynamic model,increasing the camshaft module, belt drive module and the chain drive module. The interaction between the four-cylinder and the force between the camshaft and support bearing are analyzed, and the cam profile is dynamicly corrected. During the design, taking into account the work of deformation of the valve train, so the valve train work more smoothly.