Asymmetric Gear Noise Sidebands and Application to Planetary Gear Noise Reduction

Asymmetric sidebands of gear noise are frequently observed with a planetary gear set, and are different from typical sidebands that are symmetrical around the gear mesh order (or mesh frequency). The asymmetric sidebands are found to be caused by phase differences between the different mesh points. The sidebands' locations can be calculated with knowledge of the gear set parameters. In this paper, a numerical simulation is used to predict the sidebands in a 4-speed automatic transmission. An experimental test verifies the theoretical prediction. Finally an application is described to show how to use the theory for gear noise reduction on the planetary gear set.