Lubrication Characteristics And Influencing Factors Of Diesel Engine Connecting Rod Big End Bearing

As an important power machinery,diesel engine has been widely used in different engineering fields.With the continuous improvement of the modern diesel engine strengthening,the lubrication of its sliding frictional subsets has also put forward higher requirements.As one of the main sliding frictional subsets of diesel engine,the connecting rod big-end bearing is subjected to complex alternating heat engine load,and the working conditions are worse.Aiming at the problems of poor lubrication and friction and wear of the connecting rod big-end bearing of diesel engine,the method of combining theoretical analysis and numerical simulation is used to study its profile design and bearing parameter optimization,which can improve the lubrication characteristics of the connecting rod big-end bearing and the working reliability of the diesel engine.,Has important engineering value and research significance.Taking a certain type of diesel engine connecting rod big-end bearing as the research object,the three-dimensional model is established and reduced through finite element analysis software,and the multi-body dynamic model of the connecting rod group is built in the AVL EXCITE,which comprehensively considers the elastic deformation and surface roughness of the flexible body Based on the Reynolds equation and multi-body dynamics theory,the lubrication characteristics and influencing factors of large-end connecting rod bearings are studied.Research indicates:(1)When the connecting rod bearing has dumbbell shaped,fork shaped,straight shaped and A-shaped oil grooves,Each scheme has little influence on the minimum oil film thickness and peak oil film pressure of connecting rod big-end bearing,but has great influence on the lubricating oil flow.At the same time,each bearing oil groove plan has little effect on the oil film thickness and oil film pressure at the moment of cylinder explosion pressure,but it has a certain improvement effect on the average oil film thickness and average rough contact pressure in a cycle.On the whole,different bearing oil groove schemes have little effect on the lubrication performance of connecting rod big end bearings.(2)When the connecting rod big end bearing has four types: exponential,super elliptical,barrel and trapezoid,the minimum oil film thickness of the connecting rod big end bearing increases first and then decreases with the increase of the radial change of the mould line.Small,the rough contact pressure first decreases and then increases,and the oil flow increases;when the connecting rod large-end bearing bush profile is exponential,super-elliptical and trapezoidal,the overall lubrication performance will be improved to a certain extent,and the profile diameter The improvement effect of the plan with a radial change of 5?m is better than that of the plan with a radial change of 10?m.Compared with the original scheme,when the big-end connecting rod journal has a cylindricity shape tolerance,the average oil film thickness decreases,the average rough contact pressure increases,and the oil flow decreases,which will weaken the comprehensive lubrication performance of the big-end connecting rod bearing.Therefore,for bearings with higher requirements for lubrication performance,the more strictly control their manufacturing and processing errors are required to ensure the lubrication effect of the bearings.(3)On the basis of the super-elliptical spool bearing with the best comprehensive lubrication performance optimization effect,the optimization software ISIGHT and AVL EXCITE are used for joint simulation to select the bearing clearance,bearing width,journal oil hole diameter and oil supply pressure As input variables,multi-objective optimization of the minimum oil film thickness and the average rough contact pressure of the connecting rod large-end bearing is carried out.Among them,the minimum oil film thickness increased from 1.56?m to 1.97?m,the increase rate was 0.41?m,the peak oil film pressure decreased from 231.09 MPa to 170.29 MPa,the decrease rate was60.8MPa,and the average rough contact effective pressure decreased from 3.97 MPa to0.25 MPa.The amplitude is 3.72 MPa.Finally,the comprehensive lubrication effect of the optimized connecting rod large-end bearing is improved,and the optimization effect of the average rough contact pressure is more obvious.