Prediction of Mechanical Power Loss of Planet Gear Roller Bearings Under Combined Radial and Moment Loading

Abstract

A modeling methodology is proposed to predict load-dependent (mechanical) power loss of cylindrical roller bearings under combined radial and moment loading with focus on planetary gear set planet bearings. This methodology relies on two models. The first model is a bearing load distribution model to predict load intensities along rolling element contacts due to combined force–moment loading. This model takes into account planet bearing macrogeometry as well as micromodifications to the roller and race surfaces. The second model is an elastohydrodynamic lubrication (EHL) model employed to predict rolling power losses of bearing contacts with load intensities predicted by the load distribution model. The bearing mechanical power loss methodology is applied to bearings of an automotive planetary gear set to quantify the sensitivity of mechanical power loss to key bearing, lubrication and surface parameters as well as operating speed, load and temperature conditions.