Lubrication Performance Analysising And Optimization Of Conrod Small End Bearing

Conrod small end bearing is one of the main friction pairs of engine, its lubrication state affects the engine performance and reliability directly. In recent years, with the rapid development of high power density of engine, the manufacturing technology of sliding bearing of engine is more and more attention to all aspects, especially conrod small end bearing, it has a lot of difference with other sliding bearing.For example,the unit area load is very large, the speed of the piston pin and bush is low, it is easy to cause the insufficient of oil supply pressure, high working temperature. Therefore, the research of the lubrication performance of conrod small end bearing.In this paper, took a V-shaped six-cylinder diesel engine as the research object, based on the finite element and nonlinear multi-body dynamic of the basic theory and calculated by finite means of elastohydrodynamic lubrication. Made a model of conrod small end bearing though the finite element method and got the structure condensation by modal reduction method; established one dimensional simulation model of working process of diesel engine cylinder by using Boost software and got the cylinder pressure curve; based on the previous work, established a nonlinear multi-body dynamic model of conrod small end bearing by using the AVL EXCITE software, regarded the bearing width, bearing clearance, oil groove position and the inner surface of the bush type line as the influence factors, analyzed the lubrication performance of conrod small end bearing and got the influence of these factors to the minimum film thickness, maximum film pressure, influence of lubricating oil flow and friction power.At the end of paper, optimized the original machine. The main conclusions are as follows:Increasing the bearing width makes the minimum oil film thickness increased, reduces the maximum oil film pressure and decreases the friction power consumption slightly.however, the increase of bearing width reduces the oil flow and decreases the cooling effect, which is not conducive to the normal operation of the bearing. Reducing the bearing clearance can slightly improve the minimum oil film thickness,reduce the maximum oil film pressure, decrease oil flow significantly, it is not conducive to the formation of oil film bearing lubrication. Open the oil tank should be avoided in the area of minimum oil film thickness, namely non bearing area layout of oil groove. The lining sleeve inner surface can process axial line,the selection of fitting equation(parabolic equation, arc equation and exponential equation) is not related.The selection of to the maximum radial reduction must be cautious. Through the optimization of the original machine, I improved the minimum oil film thickness and oil flow.