Nonlinear Valve Train Dynamics Simulation With a Distributed Parameter Model of Valve Springs

A simulation model of valve train dynamics was developed in order to investigate the vibrational behavior of a valve train under heavy normal load, especially for heavy-duty diesel engines. The nonlinear multi-degree-of-freedom model developed for this study uses input data resulting from the kinematic analysis. The valve spring was modeled as a distributed parameter system rather than a lumped mass system. The stiffness constants of each valve train component were theoretically obtained as nonlinear values. The partial differential equation describing the motion of the spring and the ordinary differential equations for other components, which were considered as a lumped mass system, were solved simultaneously without any iterations by using the numerical “Time Marching Step” method. The results of this simulation, which treated the elastic characteristics of each component as nonlinear, were more accurate than the previous studies that used simple linear elastic models.