Friction Prediction Method for Engine Bearings using EHD Analysis Considering Modified Friction Coefficient and Running-in depending on Lubrication Conditions

Friction reduction is one of the effective means to improve the thermal efficiency of internal combustion engine (ICE). In development of journal bearings, Model Based Development (MBD) is incorporated to study design considered the influence of the surrounding structure. However, the prediction accuracy of friction in journal bearings for engines under mixed lubrication is not sufficient. Therefore, the modified friction coefficient was introduced into the friction prediction model and running-in progression was considered. To introduce the modified friction coefficient, the parameters for aluminum alloy bearing and solid lubricant overlay bearing were identified based on the results of rig tests. As a validation, the results were compared with the engine friction tests in firing condition, and the results were in good agreement.