Thermoelastohydrodynamic Lubrication Analysis of Crankshaft Bearing Considering Crankshaft Deformation under Load

Abstract

Journal misalignment in bearing caused by crankshaft deformation under load exists generally in IC engine. When serious journal misalignment takes place, the minimum oil film thickness of bearing reduces greatly and the maximum oil film pressure of bearing increases remarkably. So, it is necessary to consider thermal effects and deformation of bearing surface when analyzing hydrodynamic lubrication characteristics of misaligned bearing. In this paper, the thermoelastohydrodymic lubrication properties of crankshaft bearings considering crankshaft deformation under load for a four-cylinder IC engine were analyzed. The lubrication of crankshaft bearing was analyzed by kinetics method. The deformation of bush surface under pressure of oil film was calculated by deformation matrix method. The crankshaft deformation and the load of crankshaft bearing were calculated by whole crankshaft beam-element method. The temperature distributions of journal, bearing and lubricant were calculated by solving 3-D energy equation and heat conduction equation. The results show that, when crankshaft deformation is considered, the thermal effects have great influence on the orbit, the maximum oil film pressure and the minimum oil film thickness of crankshaft bearing, but the thermal effects affect the end flow-rate and friction coefficient of journal much little.