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 i nvestigate the vibrational behavior of a valve train under heavy norma l load, especially for heavy-duty diesel engines. The nonlinear multi- degree-of-freedom model developed for this study uses input data resul ting from the kinematic analysis. The valve spring was modeled as a di stributed parameter system rather than a lumped mass system. The stiff ness constants of each valve train component were theoretically obtain ed as nonlinear values. The partial differential equation describing t he motion of the spring and the ordinary differential equations for ot her components, which were considered as a lumped mass system, were so lved simultaneously without any iterations by using the numerical ''Ti me Marching Step'' method. The results of this simulation, which treat ed the elastic characteristics of each component as nonlinear, were mo re accurate than the previous studies that used simple linear elastic models.