Structural Matching Characteristics Analysis And Influence Research Of Connecting Rod Small End Bearing

The connecting rod small end bearing is the bearing with the most complex motion conditions and loading characteristics and the worst lubrication condition in the internal combustion engine.Therefore,the connecting rod small end bearing is most likely to fail during the operation,especially in high-power diesel engines.Practice have proved that unreasonable structural deformation matching and structural lubrication matching are the important cause of its failure.That is why it is so important and urgent to carry out study on the structural matching of the connecting rod small end bearing under working conditions.In this paper,for the small end bearing of a high power diesel engine,it carrys out the impact of different structural parameters on the deformation matching characteristics based on thermal elastic-plastic mechanics and response surface method.Moreover,the effect of the bushing profile on the deformation matching characteristics and the lubrication matching characteristics are studied based on an elastohydrodynamic lubrication dynamics model.The main research contents are as follows:1)Working conditions of the connecting rod small end bearing is analyzed and a finite element analysis model is established which considers the elastic-plastic deformation of the bushing and the overall temperature field of the bearing.It can receive the structural deformation matching rules and the reasonable evaluation index of the connecting rod small end bearing.Moreover,for the lubricating oil film in the working process of the internal combustio engine,the influence of the piston boss oil film and connecting rod small end oil film on the bearing structural deformation matching is studied by comparing the application of several oil film loads.2)Using the response surface design method,the circular eccentricity of the small end,bushing thickness,and inner diameter of the piston pin are used as the test factor.And the maximμm contact pressure,the maximμm bushing compressive stress,and the matching contact pressure are taken as the response value to study the functional relationship and influence rules between the response variable and the test factor.The optimal design scheme is determined for the bearing structural deformation matching.3)The dynamic model of the elastohydrodynamic lubrication of the connecting rod small end bearing is established for comprehensively considering the influence of the three types of the bushing profile(parabolic profile,taper profile,and hyperbolic profile)to lubrication matching characteristics(minimμm oil film thickness and peak oil film pressure) and deformation matching characteristics.