Virtual Gear Noise Analysis and Case Design Investigation for Concept Parallel Axis Drive Unit

For electric vehicles, it is critical to develop drive units that produce a minimal amount of noise while meeting efficiency needs for a given application. Modern computational resources and accumulated experience allow for engineers to evaluate gear noise early in the development process and influence the design of the drive unit. This paper documents a high-fidelity virtual engineering approach to evaluate gear noise in a concept parallel axis drive unit and provide learnings to influence design of the external structure to improve NVH performance. By using the latest simulation tools to calculate and visualize the noise and vibration characteristics of the drive unit, designers and developers can implement design changes in optimization iterations to reduce noise and vibration. Gear harmonic response is firstly analyzed through a system model which considers structural deflection and misalignment, then a FE housing model is incorporated which is used for noise radiation evaluation and correlation. Through these procedures, different vibrational modes of the system can be examined. By identifying both problematic internal harmonics and the noisy surfaces they excite, new external housing designs can be achieved with much lower noise. Verification analysis of this design illustrates local improvement at problematic frequencies and informs on future work to further optimize gear performance.