Effective Approach to Analytical, Angle Resolved Simulation of Piston-Cylinder Friction in IC Engines

Abstract

Most frequently used approach to describe, model and analyse engine effective performance and mechanical losses is largely based on global, time/angle averaged empirical friction models. Importance of detailed, systematic approach to simulation of motor car and its real-world behaviour in terms of combustion efficiency and overall fuel consumption is greater than ever. Therefore, commonly employed empirical or semiempirical approaches seem insufficient in terms of precision and capabilities for global optimisation of power train system which poses a need to invest more attention into comprehensive angle-resolved, analytical models. Such models have been already presented elsewhere, mainly based on fundamental friction theory of Stribeck, however, simplifications in both slider mechanism dynamic and combustion simulation influenced insufficient accuracy and reliability. In this paper, detailed Stribeck’s theory based analytical approach has been employed to model friction in contact of piston ring assembly to cylinder (PRAC) and piston skirt to cylinder (PSC), as well. Gas pressure trace was measured and used to predict instantaneous indicated and effective torque based on engine 1DoF dynamic model and friction models presented in paper.