An Improved TEHL Model for Main Bearings of IC Engine with Flexible Crankshaft and Block

摘要

Considering the elastic deformation and thermal distortion of bearing surface, an improved thermo-elasto-hydrodynamic (TEHD) lubrication model for crankshaft bearings is proposed in this study. Oil film viscosity and density variation caused by temperature and pressure are considered. In addition, the mass conserving cavitation algorithm is applied in the analysis. Based on the compliance matrix method, elastic deformation and thermal distortion for the bearing surface are calculated. In order to get the temperature distribution of oil film, the energy equation which considers heat convection in three directions and heat conduction in radial direction is applied and solved by finite difference method. Meanwhile, the lubrication status of crankshaft bearing is solved by Reynolds equation, and the motion of crankshaft is solved by dynamic equations. To investigate the effects of thermal transfer of oil film on the state of bearing lubrication quantitatively, the peak oil film pressure, flow rates, minimum oil film thickness and asperity contact pressure are calculated with the elasto-hydrodynamic(EHD) lubrication model and the improved TEHD lubrication model respectively. The research results verify the accuracy of the improved TEHD lubrication model, which can effectively predict the lubrication status of crankshaft bearing.