Analysis Of The Lubrication Characteristics Based On The Considerations Of Rod Bushing Surface Morphology

Rod small end bearing is also known as the piston pin bearing and also is one of the keyfriction in the internal combustion engine.Its hydrodynamic lubrication performance has avery significant impactation in work condition of the internal combustion engine.In normalconditions,the piston and connecting rodis are connected to full floating piston pin,which canbe rotated between the piston pin and connecting rod small end bore hole.The surface ofpiston rod bushing and the pin is not absolutely smooth.It is composed of many differentshapes and sizes of the peaks and valleys.Therefore,the rod bushing surface morphology inthe study of piston pin bearing friction wear and lubrication plays a decisive impact.Firstly,the kinematics and dynamics are analyzed of the piston pin bearing in thispaper.According to the work cycle internal combustion engine piston,the load of piston pinbearing is calculated in a cycle.Secondly,the three-dimensional data of surface roughness of the three differentspecimens rod bushing is collected.By using wavelet analysis,the wavelet planes and surfaceroughness are extracted based on wavelet analysis and reconstruction principles.Comparedwith the calculated three-dimensional surface roughness and the measured value computer,therelative error is particularly small,which determines the feasibility of the wavelet analysis.Finally,based on the average flow model and asperity contact theory,a model isestablished which shows the relationship between the rod bushing surface roughness and thepiston pin bearing lubrication.By using the finite difference method,the model is soluted,andthe piston pin bearing lubrication parameters is calculated. This paper analyzes the relationship that the rod bushing with three different surfaceroughness affects to piston pin bearing lubrication properties,which is in the condiction of thesame cylinder pressure and the same crank speed.The variation of film thickness ratio,oil filmbearing capacity,asperity carrying capacity,oil film friction and asperity friction are obtainedin three kinds of surface roughness.