Analysis of Piston Skirt Friction in a Gasoline Engine

Abstract

In order to reduce the friction of the piston system, it is important to understand the friction and lubrication at the skirt and ring. In gasoline engines, the friction of the skirt is often equal to or larger than that of the ring pack, then the reduction of the friction at the skirt is indispensable. In this study, the piston skirt friction was measured by the floating liner engine which consists of independent measuring devices for skirt and ring pack friction. In addition, the skirt friction was calculated by a simulation model considered surface roughness, boundary lubrication, skirt profile and skirt stiffness. The calculated skirt friction compared with experimental data measured by floating liner method. As a result, the calculated skirt friction showed good agreement with the measured results, thus it was confirmed that the calculation accuracy of the skirt friction was sufficient. Furthermore, calculations of the skirt friction were carried out to clarify the influence of friction factors. It was also found that the skirt friction was affected by the skirt stiffness, skirt profile and skirt bearing area at the case of gasoline engines.