Elasto-Hydrodynamic Lubrication Analysis and Wear Prediction of Connecting Rod Small-End Bush and Piston Pin Interface

The coupled EHL analysis of the small-end and the piston-pin boss are carried out using a technique of successive iteration. The pin is free to rotate in both the small-end and the pin-boss. The total frictional torque is used to calculate the angular velocity of the pin. After obtaining a converged solution of pin rotation, a wear simulation is performed by carrying out an additional set of EHL analysis. Results show that the pin rotational velocity is insignificant which suggests that the EHL performance of the small-end is satisfactory. Since it is the friction between small-end bush and the pin that drives the pin to move, less pin rotation is an indication of good lubrication in the small-end interface. Hence, the technique outlined is a useful tool for establishing that the small-end/pin-boss lubrication conditions are sufficient, or when more harsh conditions are encountered, helping to optimize the design.