Modeling for design simplification and power-flow efficiency improvement in an automotive planetary gearbox: A case example

Abstract

An approach for design simplification and improvement in power-flow efficiency of an automotive planetary gearbox is presented in this article. Integrated CAD-CAE model, formed on stick diagram representation of geartrain operation, is developed for gleaning efficient gearbox configuration. A stick diagram for a three-stage planetary gearbox is a case exemplified here. CAE/simulation for dynamic analysis is conducted to determine deformation in geartrain. Powertrain model of the vehicle, Saturn-SL1, is selected from NREL ADVISOR. The power flow efficiency for each gear ratio is computed using DelCastillo's principle, and deformation is analysed to identify suitable gear ratios. It is observed that designing gearbox with five ratios yields higher efficiency than with seven. The developed model is tested on MATLAB, with New Europian Driving Cycle, to specify best operating range. Higher efficiency range is underscored, that is, driving in second through fourth gear. The proposed approach specifies driving conditions and efficiency while designing a gearbox.