Abstract
The current paper presents a method to feed back loaded tooth contact analysis results to the ease-off topography design of spiral bevel gears in order to reduce running noise. Loaded tooth contact analysis is herein implemented using a FEM solver, with additional consideration of the effects of housing deformations, bearing displacements and shaft deflections. The resulting deformations at the tooth contact are processed with the aim of pre-compensating their effect on motion transmission. The result is the noise-optimized ease-off topography design, a type of crowning special in shape and extent. Such design leads to minimum loaded transmission error, so that the gear pair will exert minimum excitation on the transmission chain. Actual tooth geometries near this optimum can be realized by higher-order modifications of CNC gear generators. The method was tested on a full scale test bench of a truck rear axle drive, and proved to be efficient in reducing gear noise. A sound pressure level decrease from 115 to 85dB was achieved at the target speed (70-80km/h truck speed), as compared to the original gear design. The essence of the proposed method lies in the ease-off topography design. All other gear parameters and drive components may remain the same. Thus it can be considered a quick-to-implement and universal method for noise reduction. As a favorable side-effect of optimization, tooth root stresses and contact pressures also reduce in general. However, it is necessary to investigate extreme operating conditions too, where the effect may be opposite.
