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It is well known that the spacing of planets in an epicyclic gear set is an important “macro” design feature that is used to balance planet load sharing, increase gear life and reduce gear whine. What is less understood is how the manufacturing tolerance of the position of the planet pins within the carrier, a “micro” phenomenon, affects the gear whine. This paper describes an analysis technique that can predict system level behaviour and shows that the inherent variability in the manufacturing processes has a very significant effect on the TE and thus generated gear whine. The manufacturing variability causes radial, circumferential and tilt displacements of planet gears - these phenomenon are all investigated.

This paper presents CAE method enhancement which realizes time domain gear noise simulation to practical use for AISIN AW automatic transmission assembly model. Today, vehicle electrification has been accelerating due to severe fuel consumption regulations. Furthermore, as quietness of interior noise of vehicle is improving, further gear noise reduction of A/T is imperative. Currently, as one of the countermeasures for realizing lightweight and NV reduction, we apply elongate holes in gear flange. Although the effect of gear noise reduction is confirmed in evaluations, the mechanism for this gear noise reduction by the elongate holes has not been clarified completely and the current simulation based on modal analysis with static condition cannot replicate actual NV phenomena of A/T assy. Furthermore, it takes an enormous amount of time and cost since the design study for elongate holes is based on the evaluation results.