Torsional Vibration Analysis of Belt-Driven Camshafts in a High Speed IC Engine

An experimental method was developed to dynamically measure rigid-body camshaft torsional vibrations in a high speed internal combustion engine. A mathematical model of the system was also created which required an accurate dynamic model of the entire valvetrain to predict the forcing function. Techniques for limiting the vibration were also implemented and tested.

While attempting to correlate the experimental and theoretical results, it was discovered that the rubber timing belt exhibits viscoelastic behavior. The system stiffness and damping coefficients are frequency dependent. A system identification was required to accurately determine these parameters.

No distinct relation between camshaft torsional vibrations and valve response was determined for the system studied. However, significant vibration reduction was achieved with a camshaft damper and an inertia addition to the camshaft.