Identification of gear rattle vibration by vibration relative approach

Gear rattle vibration signals on the transmission housing caused by unloaded gear pairs are difficult to be identified and the rattle vibration levels can not be evaluated quantitatively, because many vibration signals are included in the transmission housing when the vibration signals are recorded in the full vehicle on a chassis dynamometer. This paper proposes a rattle vibration relative approach to identify the gear rattle vibration signals. Firstly, the vibration signals on the transmission housing were filtered by ear characteristic filtering functions, and steady vibration signals were extracted by regression and smoothing processes. Then, the relative approaches of the unloaded gear vibration were obtained by subtracting the steady vibration signals from all of the filtered vibration signals. The vibration relative approaches were taken as transient vibration signals of the unloaded gear pairs. Finally, the occurrence time, frequency and the level of the gear rattle vibration were identified. Through this method, 134 rattle vibration signals of the highest relative approach were identified within 3.5 s in the full vehicle test. The results show that the rattle occurrence time obtained by the relative approaches is entirely coincided with that of the 134 rattle vibration signals which are gotten by the vibration signal playback. The result of the gear rattle vibration identification is consistent to that of the subjective perception, namely, the gear rattle vibration is identified accurately. The results of the gear vibration identification can be used to quantify the rattle vibration level, verify the theory model of rattle prediction, research the effect rule of different parameters on gear rattle vibration level, find the key factors with high sensitivity to the gear rattle vibration level and to optimize gear rattle performance. © 2015, Science Press. All right reserved.