Parameter Study and Improvement of Gearbox Whine Noise in Electric Vehicle

Gearbox whine noise can seriously reduce the interior sound quality in an electric passenger car. In this work, a six-degree-of-freedom (6-DOF) dynamic model of a helical gear system was constructed and the mechanism for generation of whine noise was analyzed. The root cause of the problem was found through noise, vibration and harshness (NVH) testing of the gearbox and the vehicle. A rigid-elastic coupling dynamics model of the reducer assembly was then developed. The accuracy of the model was then validated via modal testing. The structure-borne noise of the reducer under full acceleration conditions was predicted using the acoustic structure coupling model and the rigid-elastic coupling model of the reducer. Gear parameters including the pressure angle, the helix angle and the contact ratio were studied to determine their effects on the whine noise. Gear tooth microgeometry modification parameters were then optimized to reduce the transmission error of the first pair of meshing gears. Finally, the whine noise from the gearbox was eliminated.