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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.

For any combustion engine, balance has always been important regardless of types of cylinder layout. One of the disadvantages of the inline four engines is the second-order unbalanced forces, which leads to high-frequency excitation of vehicle’s structure and consequent internal noise. Balance shaft modules (BSM) are often used in inline-four engines, to reduce the second-order vibration and mitigate engine imbalance. Balance shafts are often running at light load and high-speed condition which could induce both gear rattle and gear whine from the BSM gear set. Typically, scissor gear set is used between crankshaft and BSM to reduce the gear rattle noise. However, a poor scissor gear design could easily lead to unpleasant gear whine noise. There is an increasing trend to shorten development cycles and reduce cost using simulation models. This paper discusses an analytical method to simulate gear whine and rattle generated by engine BSM.

The fast-growing automotive industry and rapid development of new E-drive technology nowadays brings about higher gear design requirements. E-motor applications challenge gear performance due to their higher load and speed levels compared to traditional internal combustion engines (ICE). The advantages of using asymmetric gears include lower stress, higher efficiency, better bending and contact strength, increased durability, etc. However, asymmetric gear dynamics are not well understood or analyzed. This paper performs extensive study on the effect of asymmetric gears on NVH performance of compound gear transmissions. The parametric study covers different combinations of pressure angles and root fillet settings on the drive and coast sides of the gear. The analysis is focused on the sensitivity of gear transmission error (TE) towards different symmetric and asymmetric gear designs.