The Effect of Compression Ring Profile on the Friction Force in an Internal Combustion Engine

Abstract

In an internal combustion engine piston, piston ring and cylinder are the most important assembly for transmitting the forces produced by the combustion process. The friction between piston ring pack and cylinder accounts for major portion of friction in an internal combustion engine and it also significantly affects the mechanical efficiency of the engine. In the piston ring pack, friction is mainly due to the compression ring, especially at the top dead centre and bottom dead centre where boundary lubrication exists. This paper provides a detailed study on the effect of ring profile on ring friction using MATLAB code. Three different ring profiles were selected and analysed for lubricant film thickness, ring twist angle, ring friction and friction coefficient. Out of these three, friction force and friction coefficient of one ring profile design was found minimum. The ring design with minimum friction force and friction coefficient was manufactured and assembled in a low speed SI engine. The engine liner was modified to float and friction of the ring was studied using motoring test method. The experimental results were compared with the simulation result, it was found that simulation result was in agreement with the experimental result.

Keywords

• Friction
• Ring profile design
• Simulation
• Floating liner method