Rattle detection in powertrain transmissions based on vibro-acoustical measurements

The sound of rattling is a common issue in gear transmissions, caused by the chattering of teeth during specific operating conditions. Given the growing focus on Noise and Vibration Harshness (NVH) issues in the automotive industry, identifying and explaining this phenomenon could prove beneficial. In this paper, three indices for rattle noise identification have been proposed, suitable for mechanical transmissions with gears. These indices are based on the processing of microphone signals and acceleration signals measured on the gearbox housing. The main advantage is that the accelerometers and the microphones can be simply placed on the exterior of a mechanical transmission and the experimental acquisition of these signals is accessible in a large number of configurations. Furthermore, a lumped parameter (LP) model of a transmission powertrain, capable of reproducing the rattle features, has been employed to verify the proposed indices on numerical data. Finally, an experimental campaign has been conducted, rattle and no rattle conditions have been compared and the effectiveness of the proposed indices has been proved. These techniques can be successfully used also for condition monitoring purposes.