Investigation of a bending vibration absorber and, or damper for an internal combustion engine crankshaft

The objective of this study was to invent, mathematically model, and evaluate bending vibration absorbers for use as flywheels on crankshafts of spark ignition internal combustion engines. In this study, a two dimensional discrete mass model of an inline four cylinder spark ignition engine's crankshaft was developed to predict the bending vibration response during firing. Variations of five different absorber flywheel designs were added to the model in an attempt to reduce the bending vibration. Two of these designs were invented in the course of the study. The viscous roller damper dissipated vibrational energy using viscous friction. An elastomer dissipated vibrational energy in a second design. Mathematical models of these absorber and, or damper designs were evaluated using the crankshaft model. The displacement information was analyzed using a fast Fourier transform. A theoretical damper was the only design that reduced the free end vibration through the entire speed range. Results obtained in this study show that the vibration can be reduced by the addition of a damper in place of a flywheel. Tuning the crankshaft and absorber /damper system within a smaller speed range is a more feasible solution.