In this paper a new testing methodology has been developed to objectively measure the gear rattle noise. This kind of noise has become very important especially since car manufacturers have pointed their attention to the engine noise reduction. In fact, when efforts are focused to reduce engine noise, the gearbox noise becomes more audible.
This article describes the experimental analysis that has been made to measure transmission gear rattle noise on an innovative NVH (Noise, Vibration & Harshness) transmission test rig. Also, emphasis on the capability of the test rig set-up to decouple the gear rattle noise from other vehicle noises is presented. Using such set-up, the gear rattle problem is pronounced and, consequently, noise investigation becomes easier and objective unlike what happens in a vehicle or in the power train test cell.
In order to obtain reliable results from this test rig, its performance has been correlated to measurements performed on the car. A parametric sensitivity study of the transmission gear rattle noise is also presented in this paper. Moreover, the gear rattle has been measured objectively and subjectively, in SAE scale, using several engine speed fluctuations.