Abstract: A lightweight design method is proposed for non-circular gears with eccentric characteristics leading to dynamic imbalance problems in the transmission process. Based on the elucidation of gear meshing principle, the data acquisition and modeling of non-circular gear tooth surface is realized. A multi-objective topology optimization method is adopted to optimize the spokes of non-circular gears by considering the effects of static stresses and dynamic responses of different gear tooth positions by combining the compromise planning method and the gray correlation method. The spokes are then optimized in the tooth width direction to realize the lightweight design of non-circular gears. The transmission characteristics before and after the optimized design are compared by solid data measurement and dynamics simulation analysis. The results show that the overall weight of the non-circular gear is reduced by 38.87%, and the modal order of its circumferential vibration is increased from 2nd to 3rd order. indicating improved dynamic balance. The optimized gear exhibits smoother transmission, more accurate transmission ratios, reduced tooth surface, and enhanced fatigue life. These results provide a theoretical basis for the lightweight design and transmission characteristics optimization of the non-circular gear.

Key words: non-circular gear, dynamic balance, multi-objective topology optimization, lightweighting, dynamics simulation