Optimization Design Of Elliptical Cylindrical Micro-pit Parameters On Cylinder Liner Surface

The cylinder liner-piston ring friction pair is one of the most important friction pairs in the internal combustion engine,whose friction loss accounts for 45% of the friction loss of the whole internal combustion engine.If the friction lubrication state of the friction pair can be improved,the energy loss caused by friction can be reduced,bringing huge economic benefits.As the most effective means of lubrication and friction reduction in recent years,micro-pit texture technology has received wide attention from scholars all over the world.In this paper,the friction and lubrication properties between the textured cylinder liner and the piston ring are studied from both theoretical and experimental aspects.Firstly,the friction loss mechanism of the cylinder liner-piston ring friction pair is analyzed.Through reasonable simplification and assumption,the dynamic pressure lubrication model of the cylinder liner-piston ring friction pair and the four typical shape micropore texture film thickness models are established.The oil pressure distribution of four shape textures and the tribological performance parameters of different shape textures were obtained by Matlab.The results show that the elliptical cylindrical pits and parabolic micro-pits have good oil film bearing capacity,and the square-column micro-pits are second.The positive triangle pit is the worst.Considering the processing point of view,the elliptical cylindrical pit is selected as the research object,and the influence of its geometric parameters on the lubrication performance is further discussed.The finite difference method is used to solve the Reynolds equation under the dynamic pressure lubrication condition.The super-relaxation iterative method accelerates the convergence.When the micro-pit parameters take the value: the ellipse tilt angle is 0°(the motion velocity direction is parallel to the ellipse long axis)When the depth of the micro-pit is 12?m~18?m,the area occupancy rate is 5%~20%,and the ratio of the ellipse length to the short axis is not less than 3,the average dimensionless oil film pressure is large,which is beneficial to improve the oil film bearing capacity.Finally,test verification is carried out.In this paper,laser engraving technology is used for texture processing.The laser processing technology is used to determine the optimal processing parameters: laser wavelength 1064 nm,frequency fixed at 40 kHz,output power 12 W,engraving line speed 500mm/s,engraving times 2 times.The friction and wear performance tests were carried out,and the following conclusions were obtained: compared with the smooth test piece,the friction coefficient of the test piece with elliptical cylindrical micro-pits decreased,and the elliptical cylindrical micro-pits can effectively reduce the friction between the friction pair contact faces.Wear;test micro-pit parameter range: the inclination angle is 0°,the ratio of the ellipse length to the short axis is between 3 and 4,the elliptical column-like pit depth is between 12 and 18 ?m,and the elliptical columnar pit area is occupied.The ratio is between 10% and 20%,which is in agreement with the theoretical calculation.