Design and test of a torsional vibration absorber in series with a planetary gearset

Abstract

Traditional vibration absorbers have not often been a practical solution for attenuating low frequency drivetrain modes of vibration because of the combination of the large mass and inertia and/or low stiffness, required to tune to the desired frequency. With the goal of reducing the inertia and size of a torsional vibration absorber, a unique vibration absorber was developed. Using a planetary gearset, the effective inertia of the absorber was increased without changing its physical mass, and a torsional mode below 30 Hz was successfully attenuated with physically realizable inertia and stiffness parameters. By reducing the tuned mass, the total volume claimed by the vibration absorber and planetary gearset was up to three times less than an equivalent traditional vibration absorber. A lumped parameter torsional model was developed to determine the optimal configuration of the planetary gearset input, output, and absorber inertia as well as a method to predict the optimal tuning frequency of the planetary torsional vibration absorber. A drivetrain dynamometer setup which emulates a two-degree-of-freedom torsional system was used to experimentally test and validate the performance of two planetary torsional vibration absorber prototypes built based upon the results of the lumped parameter model. The dynamometer setup was designed to have a first torsional mode around 20 Hz in which the planetary torsional vibration absorber was designed to attenuate. Based upon the experimental results of the planetary torsional vibration absorber, a reduction of over 20 dB was achieved.