Abstract
Due to the recent advances in the field of engine noise, the reduction of gearbox rattle is necessary to have a quiet environment and acoustical comfort of driver and passenger in automotive vehicles. Gearbox rattle noise results from the vibro-impacts excited by engine torque fluctuations. It depends upon many parameters such as the amplitude of engine torque fluctuation, the torsional behaviour of the drive line, and also the backlashes, inertias, drag torque of unladen gears, gearbox case structure, engine mounts, and vehicle noise and solidian transfers.
This work focus on theoretical and experimental study of torsional dynamic behaviour of drivetrain as a non linear modal system, in order to reduce the gear rattle during acceleration. The correlation between noise emitted from the gearbox and drivetrain dynamic is shown as well.
In part II, the equations of each basic driveline component are set and a global non-linear system is given. After a quick description of the integration method (II.6), a simple analysis allows to find critical speeds and thus the potential problems in a qualitative approach (II.7). In part III, the measurement method is presented, and its result permits to verify the simple analysis (III.1). To go further and to quantify and optimize gear rattle, the updating of the model is done (III.2). A numerical tuning is carried out and permits to reduce the gearbox tortional vibration and consequently gear rattle noise (III.3).