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With fast pacing development of automobile industry and growing needs for better driving experience, NVH performance has become an important aspect of analysis in new driveline product development especially in hybrid and electric powered vehicles. Differential bevel gear has significant role in the final drive. Unlike parallel axis gears such as spur or helical gear, bevel gear mesh shows more complicated characteristics and its mesh parameters are mostly time-varying which calls for more extensive design and analysis. The purpose of this paper is to conduct design study on a differential bevel gear unit under light torque condition and evaluate its NVH characteristics. Unloaded tooth contact analysis (UTCA) of those designs are conducted and compared for several design cases with different micro geometry to investigate their pattern position and size variation effects on NVH response.

In the current automotive industry, it is common that the driveline subsystem and components are normally from different automotive suppliers for OEMs. In order to ensure proper system integration and successful development of driveline system NVH performances, collaboration efforts between OEMs and suppliers are very demanding and important. In this paper, a process is presented to achieve successfulness in developing and optimizing vehicle integration through effective teamwork between a driveline supplier and a major OEM. The development process includes multiple critical steps. They include target development and roll down, targets being specific and measurable, comprehension of interactions of driveline and vehicle dynamics, accurate definition of sensitivity, proper deployment of modal mapping strategy, which requires open data sharing; and system dynamics and optimization.

This paper discusses approaches to properly design aluminum axles for optimized NVH characteristics. By effectively using well established and validated FEA and other CAE tools, key factors that are particularly associated with aluminum axles are analyzed and discussed. These key factors include carrier geometry optimization, bearing optimization, gear design and development, and driveline system dynamics design and integration. Examples are provided to illustrate the level of contribution from each main factor as well as their design space and limitations. Results show that an aluminum axle can be properly engineered to achieve robust NVH performances in terms of operating temperature and axle loads.

Overall transmission error (OTE) of gear system has been a main focus of gear dynamics study. The input-output transmission error (TE) depends heavily on mesh phasing conditions. Only reducing loaded transmission error (LTE) of a single gear mesh is not enough to ensure good NVH performance in a multiple gear mesh system. In order to predict OTE during bevel gear design instead of just analyzing single mesh TE, a new bevel gear OTE calculation method will be presented in this study. Based on single mesh parameters including loaded and unloaded TE or mesh stiffness, the OTE of a differential gear set can be calculated without building a complete system model. The effect of phasing on system OTE shows that different tooth combination can have significant effect on dynamic performance which should be considered during design.