Research Of Valve Train On Model LJ750 Engine

Valve train is one of important parts in an engine. If cam profile only relies on mapping in the research of engine,which could not change cam profile according to the performance requirements of the engine, so, this paper make LJ750 Engine an object of research with design theory and methods of modern engine .Firstly,the kinematics and dynamics model on valve train of the engine are built up with AVL-TYCON, and the original cam profile is checked with the criteria of evaluation of cam profile-design. To the problems existed in valve train,the optimal designs are put forward,and the performances of original cam profile and optimal one are analysed and compared,the results indicate that the optimal ones not only satisfy standards of kinematics; but also satisfy standards of dynamics.So,the dynamic characteristics and the kinematic characteristics of intake cam and exhaust cam are finely improved.Then,the impacting factors of the dynamics of valve train is studied, which indicate the maximum valve seat velocity increases with the increase of engine speed,and increases then decreases with the increase of valve clearance;on the whole, valve seat force increases with the increase of engine speed and valve clearance . With ANSYS/LS-DYNA, the collision between valve face and valve seat is simulated , which indicate the nodes of valve and valve seat are deformed,the velocity and acceleration change rapidly,moreover,the elements contact-stress increases with the increase of valve seat velocity in the moment of a collision.In order to further improve the existing design , the valve model of the electrohydraulic valve train is build up,and the dynamics of valve model is caculated with MATLAB,which Verifies the feasibility of the theoryThe paper lays the groundwork for further optimization of valve train and the design of electrohydraulic Valve train for LJ750 motorcycle.