Optimization of two-speed planetary gearbox with brakes on single shafts

Abstract

This paper deals with configurations of complex planetary gear trains consisting of two planetary gear trains of basic type. These gear trains are formed by linking shafts from different component gearsets and contain two carriers, and therefore designated as two-carrier planetary gear trains with four external and two coupled shafts. The structural configurations are pointed out, and additional research has been made into gear trains using coupled external shafts for torque input and output, with the controlling brakes acting on single external shafts. The kinematic schemes have been created for all analyzed PGT variants, and the available transmission ratio ranges calculated for both speeds. The transmission ratio is changed by alternating the activation of each brake, enabling their use as transmissions with two transmission ratios in transportation technology and other engineering applications. Extreme transmission ratio changes have been determined for each analyzed PGT design solution. Also, relations of ideal torque ratios to the required transmission ratios of component planetary gear trains for both speeds have been calculated. These relations enable the selection of compound gear train designs which will achieve the required pair of transmission ratios. The optimal design parameters for the adopted configuration were determined, and the optimal transmission solution for the given input data selected.