Dynamic Model and Computer Simulation of Valve Train Assemblies with Hydraulic Lash Adjuster

Abstract

Valve train design becomes an increasingly difficult discipline due to the current commercial and legislative pressures on engine design. The valve train designer must strike a balance between engine performance and valve train life. The use of features such as short cam periods and hydraulic elements requires sophisticated design techniques if good breathing and low wear are to be achieved without excessive cost or complexity. In this paper, the dynamic behavior of the finger-follower valve train system with the hydraulic lash adjuster was analyzed and a valve train model was developed by integration of the hydraulic lash adjuster model into the valve train system dynamic model. The analysis was based on variable cam angular velocity so that the program can be used to simulate the valve train system motion in either the constant engine speed or the variable engine speed operations. The effects of check valve operation and air entrainment in the oil were included in this study.