Abstract
Under certain operating conditions, rolling contacts have been shown to experience some challenges when lubricated with engine oils containing zinc dialkyldithophosphate (ZDDP) anti-wear additive. In order to better understand the main damage mechanisms during various operating conditions, further studies are needed. This article studies micro-pitting and wear damages of bearing steel surfaces under mixed lubrication conditions in a ball-on-disc setup, lubricated with different engine oils. Based on the results, micro-pitting and wear damage is shown to be highly case-dependent. In general, PAO-based engine oil tends to eliminate micro-pitting damage compared to mineral-based engine oil at less severe lubricating conditions. Moreover, a critical lambda was found for both oils, where the highest micro-pitting damage was observed.
Highlights
A crankshaft roller bearing engine presents a step into the future of internal combustion engines (ICEs)
Baubet et al [2] highlighted probable failure modes of crankshaft roller bearings lubricated with engine oils
Three different lambda ratios have been investigated for this study to explore how this will affect micro-pitting and wear damage: 0.15, 0.4 and 0.8
Summary
A crankshaft roller bearing engine presents a step into the future of internal combustion engines (ICEs). Current ICEs employ sliding bearings and their efficiency is far from optimal. By replacing sliding bearings with rolling element bearings, the engine efficiency can be improved up to 5 percent or more and, can directly reduce CO2 emissions [2,3,4]. In order to successfully employ rolling element bearings, further investigations are required for a smooth and durable operation. Baubet et al [2] highlighted probable failure modes of crankshaft roller bearings lubricated with engine oils. It was shown that micro-pitting and wear present the most likely failure modes when the anti-wear additive zinc dialkyldithophosphate (ZDDP) is present
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