Abstract: In order to study the influence of the profile parameters on the geometric performance of the variable cross-section scroll tooth, mathematical models were established for the profile area, occupancy ratio, and suction volume of III combined profile variable wall thickness scroll tooth, the relationship between the profile parameters and which are obtained. Utilizing algorithm NSGA-Ⅱ, the multi-objective optimization design is carried out with the occupancy ratio and the stroke volume as the optimization objectives, resulting in a Pareto optimal solution set of the relevant profile parameters. Subsequently, a comparative analysis is conducted between the optimized scroll tooth and unoptimized ones in terms of their geometric and mechanical performance.The result show that geometrical performance of the variable wall thickness scroll tooth is improved effectively through optimization of algorithm NSGA-Ⅱ but it is not conducive to enhancing the mechanical performance. The research results can provide valuable insights into the selection of the profile parameters in the design of the Ⅲ combined profile variable wall thickness scroll tooth.

Key words: Ⅲ variable wall thickness, geometric performance, NSGA-Ⅱ algorithm, multi-objective optimization design