Study On Surfacetexture Metrology Of Cylinder Liner-piston Ring And Method Of Running Condition Identification In Marine Diesel Engine

Marine diesel engine is the power heart of marine system, where the cylinderliner-piston ring is one of the most important rubbing pairs. The cylinder liner-pistonring of a diesel engine has a great influence on diesel engine performance (dynamicproperty, economy and reliability) and service life. Under the premise of reliable sealconditions of the combustion chamber, lubrication performance determines thefriction loss between the cylinder liner and piston ring. If the lubrication performanceis good, the friction between the cylinder liner and piston ring is small, or else, it maycause great consumption of friction power, in addition, it may lead to excessive wearof cylinder liner-piston ring and reduce its service life. Literature reviews show thatabout25-50%of the mechanical loss is contributed by the friction of the pistonassembly. It has great economic and technological significanes to study thelubrication characteristics of cylinder liner-piston ring, which will provide the guidefor the reasonable design of cylinder liner-piston ring to reduce the friction loss andprolong the service life of cylinder liner-piston ring, improve the efficiency and fueleconomy of diesel engine.This paper takes the rubbing pair of cylinder liner-piston ring in marine dieselengine as the research object to investigate the lubrication characteristics of cylinderliner-piston rings and the method of state identification. The lubricationcharacteristics of cylinder liner-piston ring in marine diesel engine including thetribological performance of the rubbing pair (the characteristics of the rubbing pairsurface, lubricating oil, the2D and3D characteristics of wear particles) and thevibration properties of cylinder liner-piston ring. The running state identificationmodel of cylinder liner-piston ring is established based on the information fusion ofvibration and tribological.Comprehensive considering the surface texture structure during the differentshape and size, the average Reynolds equation and the film thickness equation isintroduced to establish the hydrodynamic lubrication theory model of differentsurface textures. Then, a multiple grid method is used to numerical simulation. Theaffect of lubrication performance between the cylinder liner and piston ring on different surface textures is analyzed through numerical simulation.Based on the theoretical analysis, Different surface textures (such as differentsizes of surface concaves and grooves, etc.) were designed and produced on thecylinder liners using surface treatment. A series of experimental tests were thencarried out in a specially designed diesel engine tester which was used for friction,wear and vibration test of the main moving components. Collected the vibrationsignal of diesel engine, the analysis methods of wavelet packet decomposition andbispectrum were used to extract and analysis the feature vector which characteristicthe vibration characterization of different surface textures. Then, the correspondingrelationship between cylinder liner’s surface textures and vibration signal of dieselengine was investigated.The lubrication oil was collected in the operation process of the diesel engine.The mapping relation between element content of wear particles and the cylinder linerwith different surface textures was investigated through the oil analysis. Thefiltergram method was performed to identify the fundamental mechanisms of thewear processes. The relationship between the characteristics of wear particle andsurface textured cylinder liners was obtained through the method of numericalanalysis. The influence of cylinder liners’ surface texture to the friction and wearperformances of the rubbing pair was investigated through comparative analysis thecylinder liner inner surface before and after the test. Comprehensive the aboveinformation, the mapping relationships between surface textures and the tribologicalproperties of cylinder liner-piston ring were investigated.In order to further analyze the performance of cylinder liner-piston rings withdifferent surface textures and real-time monitor the running state of this rubbing pair,the technology of running state identification was proposed in this paper based oninformation fusion of vibration and tribology. With the development of the oil onlinemonitoring technology, it is believed that key friction parts of diesel engine can beidentified according to this identification method in the non-stop, non-removerunning state.