Lifetime Performance Prediction Of Piston Ring Pack-Cylinder Liner System In Distributed Resource Environment And Low Friction Design Research

The number of global vehicle automobile increases every year and scarce resources and environmental pollution are increasingly more serious,mankind is faced with unprecedented energy pressure and environment pressure.The reciprocating piston internal combustion engine(ICE)is the main power source in human life and production and the friction and energy consumption reduction of ICE in the lifetime has been the most urgent pursuit of the practitioners in this field.In order to achieve the low friction design of ICE in the lifetime,this paper researches the lifetime performance prediction method.Then,this paper considers the piston rings-cylinder liner system as the research object,establishes its lifetime performance prediction model,and analyses the change of the structure and performance in the running-in process and steady state.Due to the knowledge lack of a resource unit,this paper researches the knowledge service and its achieving method in the lifetime performance prediction.The main work and contributions of this paper are as follows.Firstly,the effect of the structural change,caused by the wear,on the lifetime performance of machines is analyzed.And for internal combustion engine,the lifetime performance prediction framework is proposed.Then for the piston rings-cylinder liner system,on the basis of the two-dimensional average Reynolds equation and Greenwood-Tripp model,this paper establishes the lifetime performance prediction model by considering the kinematics and dynamics of piston assembly,blow-by of piston rings,viscosity-temperature characteristics of oil lubricant,cylinder liner deformation and piston ring conformability,surface roughness of piston rings and cylinder bore,wear and so on.The effects of cylinder liner deformation and piston ring conformability on blow-by,lubrication and wear properties of piston rings are analyzed by this model.This work establishes the foundation for realizing the low friction of engine piston ring pack-cylinder liner system in the lifetime.Then,based on the lifetime performance prediction model,the tribological performance of piston rings-cylinder liner system under cold start-starved,cold startflooded,cold idle and warm idle operating conditions is analyzed.The blow-by,lubrication and wear of piston rings under different operating conditions are studied.The research shows that during the cold start-starved,the oil film of the piston ring pack is thinner,the frictional force and friction mean effective pressure(FMEP)is greater and the wear of piston rings is more severe.And then,considering the non-flat piston ring profile,the uneven wear model of piston ring rough surface is built.And the wear coefficient in this wear model is determined by the experiment.Running-in behavior of the surface roughness at different small regions of piston rings is studied by this model.The effects of the realtime change of the rough surface topography on the lubrication,friction and wear behaviors are also discussed.Then after running-in period,this paper predicts the lifetime performance degradation process of piston rings-cylinder liner system,which is from steady wear stage to severe wear stage,until failure.The above analysis establishes the foundation for performance optimization of piston rings and cylinder liner system in the lifetime and the achievement of the low friction.Due to the complexity of lifetime performance prediction,a resource unit is difficult to master the related knowledge of all disciplines and parts.According to this situation,this paper also researches the knowledge service method in the lifetime performance prediction.Considering the key friction pair of the engine as low friction object,the knowledge service website is built,and the corresponding client and server components are developed.Taking the tribological performance analysis of piston skirt and cylinder liner system,the tribological performance analysis of the crankshaft and bearing,the tribological performance analysis of piston rings and cylinder liner system,and Modelica numerical calculation knowledge service as example,the effectiveness of the knowledge service is verified.