Diesel Engine Bearing Elastohydrodynamic Lubrication Characteristics Research

The modern internal combustion engine need the reduction of it's mass, bulk, vibration and noises, fuel consumption, costs, and the right design style to meet the demand of market, as well as more powerful and high rotating speed. The variational loads of crankshaft main bearings and the connecting-rod big-end bearings are so large that do harm to the bearing lubrication. Consequently, the lubrication research of main bearings and connecting-rod big-end bearings play an important role on it's analysis of damage, lubrication design and reliability.This article described the analysis of crankshaft bearing lubrication, systematically elaborated the hydrodynamic lubrication theory of slide bearings, including the formation of dynamic pressure principle, the derivation of Reynolds equation, boundary conditions and the lubrication parameter calculation. The AVL EXCITE software has been used to establish the main bearings and connecting rod bearing elastohydrodynamic lubrication model of a two cylinder diesel engine crankshaft, calculated and analysed the crankshaft main bearing and connecting rod bearing loads, the minimum film thickness, maximum film pressure and friction losses.Calculated and analysed the bearing lubrication factors which affecting the lubrication characteristics of two-cylinder engine crankshaft main bearings and connecting rod big-end bearings, analyzed the layout scheme of crankshaft balancing mass which affects main bearing lubrication characteristics and the connecting rod bearing clearance, connecting rod and crank pin bearing width of the oil diameter of three important factors which affect connecting rod bearing lubrication properties.The results show that:in range of engine speeds, the minimum oil film thickness, maximum film pressure and other important parameters of the two cylinder diesel engine main bearings and connecting-rod big-end bearings are within the limits, fulfil the design requirements, but the second main bearing shaft and connecting rod bearings need to do further optimizing. Through the analyze of influence factors on the crankshaft main bearings, connecting rod bearing lubrication parameters, the best solution were find for the optimum balancing mass of the crankshaft and the combination of connecting rod bearing clearance, bearing width, crank pin hole diameters.