Transfer of the Method for the psychoacoustic Design of Ground Bevel Gears extended by the Application of a Targeted Micro Geometry Scatter

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The requirement on gears and transmissions are determined by external conditions as the legislation as well as the competitive situation on the world market. The continuous demand for higher power densities for the increase of the efficiency can be achieved by a reduction of the involved masses and by an increased load-carrying capacity via new materials. Furthermore, a major requirement by the transmission is a low noise level. Especially bevel gears, with comparatively low contact ratios because of the high values for the modifications, are often described as noise critical.Lapped bevel gear set are perceived as being quieter or smoother compared to ground bevel gear sets. Current investigations lead to the fact that the manufacturing related microgeometry scatter and pitch deviation can be identified as the root cause. Ground bevel gears in contrast have a high reproducibility of the manufactured geometry with low pitch deviations. The high reproducibility of the geometry may lead to a tonal noise spectrum. The implementation of targeted pitch deviations is used for fan applications to reduce the amplitudes of higher harmonics of the rotor blade frequency. In gear applications, the pitch deviation for reduction of tonality is avoided, as it may lead to premature tooth meshing which lead to a decrease of the load-carrying capacity. The aim of this research project is the transfer of the method for psychoacoustic design of bevel gears on an automotive application. Therefore, the existing methods of the dynamic simulation of the tooth mesh and the psychoacoustic design of gears provide the basis for the project and will be extended for the simulation of a complete tooth hunt in order to implement an increase of the background noise level by a targeted topography scatter. The topography scatter is used to reduce the tonality of the noise spectrum. Using the FE-based tooth contact analysis, a simulation of a gear set with individual micro geometries for each tooth is realized. In order to assure the productivity of the process The manufacturing process of the topography scatter needs to be realized without an extra dressing operation. Furthermore, it is necessary to define the microgeometry scatter which avoids disadvantages for the load-carrying capacity. The transferred methods and the gained knowledge will be applied on an automotive transmission and will be validated by test rig trials and vehicle measurements. The result of the planned research project is a novel method for optimizations of the acoustic behavior of bevel gears based on a targeted topography scatter.