Investigation of friction power losses in automotive journal bearings

Journal bearings are used in a large number of critical positions in automotive internal combustion engines (ICE) and contribute a major contribution to the total friction power losses in these engines. These reasons motivate in addition the accurate and reliable simulation of the operating conditions and friction power losses in journal bearings. In this work the lubrication of journal bearings is investigated in detail using detailed rheological lubricant models that include the piezoviscous effect. To describe mixed lubrication realistically in the simulation, a sophisticated contact model is employed together with measured surface roughness data from journal bearings. Starting point is an extensive thermo-elastohydrodynamic (TEHD) simulation, which yields important insights into the thermodynamical behavior of the lubricant film in journal bearings. From these results, a powerful isothermal elastohydrodynamic (EHD) simulation model is derived that calculates the oil temperature for the simulation from two easily accessible experimental temperatures. The capabilities of the presented simulation methods are compared to extensive experimental measurements performed on a journal bearing test-rig, which show excellent agreement.