Geometrical Optimization of the EHL Roller Face/Rib Contact for Energy Efficiency in Tapered Roller Bearings

Sven Wirsching,Thomas Stahl,Sandro Wartzack,Max Marian,Marcel Bartz

doi:10.3390/lubricants9070067

Sven Wirsching, Thomas Stahl + Show 3 more

Open Access

https://doi.org/10.3390/lubricants9070067

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Abstract

In the context of targeted improvements in energy efficiency, secondary rolling bearing contacts are gaining relevance. As such, the elastohydrodynamically lubricated (EHL) roller face/rib contact of tapered roller bearings significantly affects power losses. Consequently, this contribution aimed at numerical optimization of the pairing’s macro-geometric parameters. The latter were sampled by a statistical design of experiments (DoE) and the tribological behavior was predicted by means of EHL contact simulations. For each of the geometric pairings considered, a database was generated. Key target variables such as pressure, lubricant gap and friction were approximated by a meta-model of optimal prognosis (MOP) and optimization was carried out using an evolutionary algorithm (EA). It was shown that the tribological behavior was mainly determined by the basic geometric pairing and the radii while eccentricity was of subordinate role. Furthermore, there was a trade-off between high load carrying capacity and low frictional losses. Thereby, spherical or toroidal geometries on the roller end face featuring a large radius paired with a tapered rib geometry were found to be advantageous in terms of low friction. For larger lubricant film heights and load carrying capacity, spherical or toroidal roller on toroidal rib geometries with medium radii were favorable.

Highlights

Tapered roller bearings (TRBs) are being widely used for high load supporting applications in mechanical, automotive and transmission engineering where their main characteristics—high radial and uniaxial load carrying capacity, demountability and adjustable clearance—can be fully exploited
Based on the geometric parameters describing the roller end face and rib geometries, they were sampled by a statistical design of experiments (DoE) and the tribological behavior was predicted by means of elastohydrodynamically lubricated (EHL) contact simulations
For each of the geometric pairings considered, a database was generated on the basis of which key target variables such as coefficient of friction (COF), maximum pressure and minimal lubricant film height were approximated by a meta-model and an optimization was carried out

Summary

Introduction

Tapered roller bearings (TRBs) are being widely used for high load supporting applications in mechanical, automotive and transmission engineering where their main characteristics—high radial and uniaxial load carrying capacity, demountability and adjustable clearance—can be fully exploited. They are frequently found, for example, in rail or passenger vehicle wheel hub assemblies, gas turbine engines or worm and bevel gear stages or differentials [1]. Despite secondary contacts or the micro-geometry were analyzed in few studies [9,10,11], most efforts focused on the macro-geometry of primary contacts between rolling elements and raceways, for example by profiling/crowning [12]

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