Influence of the Cylinder Block Dynamic Stiffness and the Crankshaft Damper Characteristics on the Three-Dimensional Vibrations of the Crankshaft-Systems.

Abstract

Three-dimensional vibrations of the crankshaft system under running conditions were inves- tigated for an automobile engine, taking account of the dynamic behavior of cylinder block and torsional damper. To simplify the analyses, the crankshaft was idealized by a set of jointed structures consisting of simple round rods and simple beam blocks of rectangular cross-section. The main journal bearings were modeled by a set of linear springs and dash-pots. For the flywheel, the dynamic stiffness matrix was derived from FEM. For the cylinder block, the dynamic stiffness matrix was constructed from the modal parameters obtained from the experimental modal analysis because of the complicated structure. Then the dynamic stiffness matrix was constructed for the crankshaft-cylinder block system, by the principle of superposition. The three-dimensional vibra- tions of the crankshaft system were analyzed for the two cases in which a solid pulley and a crankshaft damper were attached to the crankshaft. The calculated results were compared with the experimental results. In the analysis, influence of the vibration amplitude and temperature of damper on the damper characteristics were taken into account. The influences of the dynamic stiffness of the crankshaft thrust bearings and the oil film on the vibrations behavior of the crankshaft system were also investigated.