Study On Sliding Problem Of Diesel Engine Connecting Rod Bush Based On TEHD Theory

The current requirements of the intensity of the internal combustion engine is getting higher and higher,so that the trend of connecting rod bush failure cases are also rising.In this paper,the multi-body dynamics analysis and the thermo-elastic-plastic finite element simulation are carried out to analyze the reason why the bush is slipping in detail,for the sliding problems of the connecting rod small end bush under the influence of the spatial position,the oil supply mode,the high temperature and the high pressure.By using the method of changing the parameters of the connecting rod bush,a reasonable suppression scheme is put forward,which can effectively restrain the slippage of the connecting rod bush.The main tasks of this paper are as follows:Firstly,a simplified multi-body dynamics model was established by using nonlinear multibody dynamics theory in AVL-EXCITE software based on the actual working condition of a V type six cylinder diesel engine.The thermo elastic fluid hydrodynamic lubrication model was used to calculate the connecting rod small end bush,which took into account the thermal effect,the hole effect and the elastic deformation.By analyzing the maximum oil film pressure,minimum oil film thickness,temperature distribution,other lubrication characteristics,orbital path and total friction loss in detail,the results showed that the piston pin was in contact with the bush and the friction occurred in the maximum explosion pressure conditions.Then,By using the oil film pressure and the temperature distribution as the boundary conditions,the thermo-elastic-plastic finite element model of the connecting rod small end bush was established in Abaqus.The results of the contact pressure,equivalent stress and plastic deformation of the connecting rod bush under the maximum compression condition were analyzed in detail,which showed that the reason for the slippage of the connecting rod bush was that the dynamic moment was greater than the resistance moment.Based on the reason of the slippage of the connecting rod bush,a design scheme for restraining the slippage of connecting rod bush was proposed by changing the radial clearance,oil supply pressure,surface roughness and inner surface.Finally,the rationality of the design was verified by calculating the contact pressure of the liner.