Study On Performance Optimization And Coupling Mechanism Of Textured Cylinder Liner-piston Ring In Diesel Engine

As one of the core friction pairs of diesel engine,the performance of cylinder liner-piston ring(CLPR)assembly has a significant impact on the efficiency,service life,reliability and economy of diesel engine.Relevant research shows that the mechanical loss caused by CLPR accounts for about 40%-60% of total mechanical loss of diesel engine.In addition,all kinds of accidents caused by poor lubrication also account for a large proportion in ship maintenance.Surface texture is designed to improve tribological performance by machining a certain sized texture structure on CLPR.The optimization design of texture is always the key point of research.Therefore,in order to improve the reliability,improve diesel engine efficiency and reduce operation and maintenance cost,the performance optimization of textured CLPR is particularly important.In this paper,CLPR of diesel engine was taken as the research object.The purpose was to improve the efficiency and reliability of diesel engine.The groove texture was machined on cylinder liner,the dimple texture was machined on piston ring,and the co-texture was formed.The basic research of pin-disk,the feasibility verification of slices,and the performance research of whole cylinder liner were carried out respectively,and compared with non-textured and single-textured surface.Direct characterization parameters such as friction coefficient,wear losses,wear morphology and indirect characterization parameters such as electron microscope energy spectrum,contact resistance and cylinder pressure were adopted.Performances of friction,wear,lubrication and air tightness were analyzed and characterized.Based on the above parameters,the mechanism of single texture and co-texture was analyzed.It provided a reference for the optimum design of textured CLPR.The experimental results showed that single cylinder liner groove texture,single piston ring dimple texture and co-texture with proper sizes effectively increased oil film thickness and improved the tribological performance.As a dynamic oil storage structure,piston ring dimple texture carried lubricating oil to play a role in whole contact surface.Its oil film improvement ability was stronger than cylinder liner groove texture’s,as a static oil storage structure.Groove texture on cylinder liners,as a static debris trapping structure,prevented the debris in texture from escaping and participating in wear again.Its wear resistance was stronger than the piston ring dimple texture’s,as a dynamic debris trapping structure.The co-texture combined the advantages of cylinder liner groove texture and piston ring dimple texture,further improving oil film characteristics and debris trapping efficiency.The oil film thickness of co-texture increased by 98.4% averagely compared with that of non-texture under the whole cylinder liner tests,and wear resistance was also the strongest.Oil film characteristic were closely related to air tightness.Single cylinder liner groove texture formed a high-low staggered oil pressure distribution on cylinder liner,and single piston ring dimple texture formed an arc oil pressure distribution on cylinder liner.The air tightness was improved by 4.6 k Pa and 7.8 k Pa respectively in the dead center.For co-texture,there was a staggered oil pressure distribution on the basis of arc oil pressure distribution.The air tightness in middle was improved by12.3 k Pa,and the optimal air tightness was obtained.