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In current design optimization of engine crankshaft bearing, only the crankshaft bearing is considered as the studying object. However, the corresponding relations of major structure dimensions exist between the crankshaft and the crankshaft bearing in engine, and there are the interaction effects between the crankshaft and the crankshaft bearing during the operation of engine. In this paper, the crankshaft-bearing system of a four-cylinder engine is considered as the studying object, the multi-objective design optimization of crankshaft bearing is developed. The crankshaft mass and the total frictional power loss of crankshaft bearings are selected as the objective functions in the design optimization of crankshaft bearing. The Particle Swarm Optimization algorithm is used in the optimization calculation. The optimization results are compared to the ones of original engine design and the single-objective design optimization of crankshaft bearing.

There is the direct interaction between the crankshaft and the crankshaft bearing in an internal combustion engine. Current lubrication analysis of the crankshaft bearing was generally limited in the tribology discipline, only the factors relating to the bearing were considered, and the journal axis was generally supposed to be parallel to the centerline of bearing. In reality, the crankshaft deformation under load will result in the journal misalignment in the bearing. Although the journal misalignment was considered in a few of the lubrication analyses of crankshaft bearings, the causes of journal misalignment were usually thought to be caused by the manufacture, the assembly errors and the deformation of cylinder block. In order to simplify the problem, the journal misalignment was generally assumed to have constant magnitude and direction in an operating cycle of engine.

The actual engine (especially vehicle engine) does not always operate under rated operating condition and its operating condition changes constantly. However, only the lubrication performance of crankshaft bearing at rated engine operating condition has been generally analyzed in current design and research of engine crankshaft bearing. In this paper, a four-stroke four-cylinder engine is taken as the studying object, the load and lubrication of crankshaft bearing under different operating conditions are analyzed systematically and comprehensively. The load of connecting-rod bearing is calculated by the dynamic calculation method, the loads of all crankshaft main bearings are calculated by the whole crankshaft solid-element finite element method, and the lubrication performance of crankshaft bearings are analyzed by the dynamic method.

The lubrication analysis of IC engine piston ring is usually carried out under engine rated working condition. In actual use, the IC engine (especially the vehicle engine) does not always operate in rated working condition, and its working condition will be changed frequently. In this paper, an IC engine is taken as the studying object, based on the measured gas pressure in the engine cylinder, the lubrication characteristics of piston ring under different engine working conditions is analyzed in which the transport of lubricating oil between the piston ring and the cylinder liner is considered. The results indicate that the engine working condition has remarkable influence on the lubrication characteristics of IC engine piston ring. The worst lubrication status of piston ring may not occurred in the engine rated working condition.