Research on the torque transmissibility of the passive torsional vibration isolator in an automotive clutch damper

The input torque vibrations (i.e. the fluctuations or ripples) induced by internal-combustion engines is a significant source of noise, vibration and harshness issues, which cause problems in automotive powertrains. This is because the torque vibrations are primarily transmitted to the input shaft of automotive transmissions (e.g. automatic transmissions) when the lock-up clutch is closed. Hence, a passive torsional vibration isolator with helical springs is generally inserted between the engine and the transmission to isolate the input vibratory energy. Although a passive isolator is used to resolve the noise, vibration and harshness issues because it generally exhibits frequencies with a very low transmissibility, the primary performance of the isolator is evaluated using only the static torsional spring characteristics and the measurement of the angular velocity or the angular acceleration. In this study, a low-inertia dynamometer incorporating state-of-the-art torque-sensing technology was used to evaluate experimentally the torque transmissibility of a torsional vibration isolator as a primary dynamic performance index for the first time.