An Investigation on the Correlation between Integrated Electric Motor Reducer Shaft Movement and Gear Vibration

Dynamic and static shaft eccentricity in integrated electric motor-reducers can lead to variations in the motor air gap and elevate both the motor and gear noise levels. This study investigates the effects of static and dynamic eccentricity, along with the presence of wave washers, on the gear noise of an integrated electric motor-reducer system. The results indicate that shaft eccentricity substantially increases both the orbit radius and width magnitude, with enhancements of up to 1.33 times and 4.57 times, respectively, under static and dynamic eccentricity conditions. Although the axial motion remains relatively small(under 10 μm), its magnitude is intensified by the absence of wave washers and the presence of eccentricity. A novel correlation between shaft motion and gear vibration was identified, illustrating that shaft movement induced by eccentricity has a direct impact on gear meshing dynamics. The absence of wave washers, coupled with static eccentricity, was associated with a maximum increase of 25 dB in gear vibration. These findings underscore the critical importance of closely regulating shaft eccentricity and related parameters to optimize motor-reducer performance and minimize gear noise in electric vehicles.