Research On The Establishment Mechanism Of Pressure Lubrication Oil Film Of Splash Lubrication Of Swinging Friction Pair

Since the internal combustion engine came into being,it has brought tremendous changes to people’s lives and production patterns.With the advancement of industrialization and the continuous improvement of people’s material living standards,the tests of various working indicators of internal combustion engines are becom ing more and more stringent and meeting the basic requirements of many indicators has always been a requirement of reliability.The connecting rod small end bearing,and the piston pin is a typical wobble friction pair in diesel engines,and one of the worst motion pairs in the loaded environment as well.It adopts splash lubrication method,and its surface lubrication will affect directly the overall reliability of the engine.Therefore,the research on the lubrication mechanism and influence law of the swinging motion pair is of great significance to the design of the engine swinging pair and improving the reliability and service life of the diesel engine.Therefore,the research on the lubrication mechanism and the influence law of the swinging pair is of great significance for its design and improving the reliability and service life of the diesel engine.The paper takes the high-density diesel connecting rod small head bearing and piston pin as the research object,the multi field coupling,multi-body mechanism dynamics and dynamic pressure lubrication as the research theory,and the splash oil lubrication and swing motion characteristics of the motion pair as important influencing factors to study the sucking,spreading and the establishment of the pressure-bearing oil film between connecting rod small end bearing and the under the condition of oil supply lubrication.Through the combination of numerical simulation analysis and simulation test verification,the pumping effect" and "stop point effect" are introduced to establish a mathematical model of splash lubrication of the swinging motion pair to explore the influencing factors and the law of the splash lubricant film formation,and to analyze the causes of abnormal wear of connecting rod small-end bearings.The results indicate that:(1)During the compression stroke and the power stroke,the small end connecting rod bearing is heavily loaded,and reaches the peak at the beginning of the power stroke and the end of the compression stroke.At this time,the minimum oil film thickness reaches a minimum value,and the main friction loss of the bearing is roughness friction loss.Besides,in the vertical direction,the eccentricity of the piston pin is large;the oil grooves and oil holes can alleviate the lubrication of the bearing,and the oil grooves and oil holes should be located in the non-bearing area.(2)When the oil supply is sufficiently supplied,the minimum oil film thickness of the bearing increases and the friction loss power decreases with the increase of engine speed.With the increase of bearing clearance,the inflow and outflow of lubricating oil,but the total peak pressure of the bearing increases sharply,the minimum oil film thickness of the bearing decreases,and the friction loss power of the bearing increases.As the roughness point of the bearing becomes larger,the minimum oil film thickness increases,the total peak pressure of the bearing decreases,and the oil flow rate of lubricating changes little,but the friction loss power increases greatly,which is not conducive to bearing lubrication.With the increase of piston pin diameter,the minimum oil film thickness of bearing increases,friction torque decreases,total peak pressure decreases,roughness friction loss decreases,and hydraulic friction loss increases.(3)The increase of bearing assembly interference will lead to the increase of contact pressure and plastic deformation under the influence of thermal effect.When a certain degree is reached,the bearing will rotate and finally loosen.Therefore,while ensuring the lubrication performance of the bearing,it is necessary to select the appropriate assembly interference.(4)Simulate the bearing lubrication conditions under different working conditions according to the swing friction and wear test machine to verify the simulation calculation results of the oil film influence law.Use the high-temperature torsion testing machine and WE-300 electronic universal testing machine to verify the effect of the interference of the bushing on the bearing loosening.Analyze the test result data,and the result is basically the same as the simulation calculation law.