Abstract
Keywords: Gear, Rattle, Noise, NVH, Gearbox, Transmission.
Nowadays one of the car manufacturers challenge is on comfort, in particular there is a huge demand of noise reduction: customers are now much more critical about the noise inside and outside their vehicles. In this study we have focused our attention on a particular gearbox noise: the gear rattle. This noise has become more important than in the past soon after the car manufacturers has pointed their attention to the engine noise reduction: in fact as quieter become the engine as noisier seems to be the gearbox.
Aim of the following article is to describe the experimental analysis that we´ve done in order to develop a new testing methodology to measure the transmission gear rattle on a car.
This kind of noise, up to now, has been analysed principally in subjective way, because of the difficulties of the objective evidence: usually, the analysis are performed by a jury of experts that gives a rate on SAE scale. This new methodology allow the transmission manufacturers to have a new tool for the objective evaluation of the gear rattle noise just doing an easy set of measurements: correlating this set of measurements with the subjective evaluation, we´ve also found a criteria for a quickly on line evaluation of the gear rattle noise.
With this study a new testing methodology for the gear rattle noise is found, next step is to generalized this methodology also for other kind of gearbox: this is a starting point for the future "quiet" gearbox.