Study And Improvement On The Mechanism Of The Reduction Of The Excess Force Of Connecting Rod Lining Based On AVL Excite

Taking the connecting rod small head bearing as the research object,the flexible Body dynamics(EHD)lubrication model of piston,connecting rod and bearing is established with the help of the PU module of the commercial development software AVL,and the working parameters(explosion pressure in diesel engine cylinder,diesel engine speed,incomplete lubrication of spent oil of unit parts)and structural parameters are considered(The mechanism and lubrication characteristics of the overflow force of connecting rod small head sliding bearing are analyzed by factors such as bearing type line,piston pin stiffness,bearing coordination clearance and surface roughness).Based on the dynamic model of flexible multi-body ehd of crank linkage mechanism,considering the elastic deformation and surface roughness contact of piston pin and sliding bearing,the lubrication characteristics of the small end sliding bearing of connecting rod are analyzed,and the influence law of the working parameters and structural parameters of piston pin sliding bearing on its lubrication characteristics is simulated and analyzed.The optimum bearing clearance of the small end sliding bearing of connecting rod generally takes the 0.8‰~1.5‰ of the axle neck,in this reasonable range,the smaller bearing clearance is conducive to the formation of an effective lubricating oil film,with the increase of bearing clearance,the minimum oil film thickness shows a decreasing trend,when the bearing gap is 0.025 mm,the minimum oil film thickness to obtain a maximum value;The shaft repair type makes the piston pin line and pin hole good fit can reduce the flange effect better,after repairing the connecting rod small head hole in the maximum combustion pressure moment the maximum rough contact pressure significantly lower than the pre-repair;Reducing the diameter of the inner hole of the piston pin and increasing the stiffness of the piston pin can also reduce the flange effect,the lubrication of the sliding bearing is improved,and the change of the peak oil film pressure appears to decrease first and then increase the trend;The surface roughness of the bearing increases from 0.2 micron to 1.0 microns,which has a significant effect on the lubrication performance of the minimum oil film thickness,oil film pressure and friction loss power of the connecting rod small head sliding bearing,and the minimum film thickness is from 1.091 ?m increased to 2.091?m,increased by 91.66%,peak oil film pressure showed a decreasing trend,wear also increased,friction loss power is rising,from the beginning of 0.157 kW to 0.411 kW,increased by 161.78%,the increase of surface roughness of sliding bearings will improve the thickness of the oil film to a certain extent,and thus reduce the pressure of the oil film,but with the increase of roughness will also lead to increased friction and wear,will cause friction loss power is rising.