A design framework to improve the dynamic characteristics of double planet planetary gearsets

Abstract

Double planet planetary gear sets have significantly more design options than their single planetary counterparts as the addition of the second planet set allows for greater flexibility in sizing and synthesizing transmission kinematic chains. Generally, the primary design constraints for these systems are based on transmitted load, speed ratio, and availability of space. However, once these specifications are met, few attempts are made to optimize the design any further as manual design techniques fail to assess all performance related aspects of the system. In this paper, a methodology to improve existing double planetary gear sets through adjustment of limited set of feasible design constraints is proposed. The improvement will be achieved through modifying the values of gear tooth profile shift, tooth thickness, and planet gear center distances. Design of experiments (DOE) approach is implemented to generate a finite set of models that accurately represent the entire design space. In order to investigate if the proposed alternative designs are an improvement from the baseline system, a finite element tool is used to model all of the potential configurations. The parameters that are used for the fundamental measurement of system performance in this study are bearing forces, gear mesh forces and transmission error spectra.