In modern automotive vehicles, gear noise becomes more and more of an issue. The main reason is the reduced masking noise of the engine, which vanishes completely in the case of an electric driveline. Improved gear quality unfortunately does not correlate with a better noise performance in any case. High gear quality makes sure that the gear flanks are inside tight tolerances and that all teeth are nearly identical. Even if the running behavior of such gear sets shows a very low sound pressure level, the noise perception for human ears may be annoying.
The deformation of the gear teeth due to load conditions may cause premature tooth meshing. This irregular tooth contact causes increased stress on the tooth flank. These adverse effects can be avoided by using defined flank modifications, designed by means of FE-based tooth contact analysis.
Helical gear teeth are affected by cratering wear — particularly in the regions of low oil film thicknesses,
high flank pressures and high sliding speeds. The greatest wear occurs on the pinion — in the area of
negative specific sliding. Here the tooth tip radius of the driven gear makes contact with the flank of the
driving gear with maximum sliding speed and pressure.