Optimal design with diagonal modification for reducing helical gear noise

An approach based on the minimum amplitudes of loaded transmission error, meshing impact force and vibration acceleration for diagonally modified helical gears was proposed to reduce vibration and noise. Firstly, the modified tooth surfaces were represented with a sum of two vector functions determining the theoretical tooth surface and the deviation surface, the latter was fitted with 3 B-Splines based on tooth surface grid data obtained with the designed deviation curve. Secondly, with the tooth deformation ascertained with TCA and LTCA, the meshing force and meshing stiffness were calculated according to the meshing impact theory. Finally, a dynamic model for a pair of helical gears was built to get the best deviation surface using the genetic algorithm. The example results showed that the diagonally modified helical gears can greatly reduce vibration and noise due to the varying of mesh-in and mesh-out positions of the modified gears, very small loads on mesh-in and mesh-out ends, and higher coincidence level than other type modified gears.