Study on movement characteristics of floating piston pin

The movement characteristics of floating piston pin in engine were analyzed using the EHL theory, the average flow model and the asperity contact theory, the finite element method (FEM), the finite difference method (FDM) and the multi-body dynamics (MBD) based on component mode synthesis. The effect of the surface roughness of connecting rod small end bush on the movement characteristics of piston pin during engine running-in was also analyzed. The results show that the piston pin rotation speed increases rapidly before the top dead center of compression stroke and remains substantially stable in the second half of the exhaust stroke and in the first half of the intake stroke, and the direction of mean piston pin rotation in one work cycle is opposite to that of crankshaft. There are three maximum points on the curve of moment friction torque produced by the connecting rod small end bush and two maximum points produced by the piston pin bore. The mean rotation speed of the piston pin in one work cycle decreases when the roughness of the small end decreases during the running-in.