A Three-Dimensional Analysis of Piston Ring Lubrication Part 2: Sensitivity Analysis

Abstract

A three-dimensional model, developed by the authors, incorporating axial and circumferential variations in film shape and squeeze effects has been presented in Part 1 (1). In order to verify this model, the minimum film thicknesses predicted by the authors' model are compared with the predictions of an axisymmetric (two-dimensional) theory and with experimental results presented by Brown (2). A sensitivity analysis is then presented. A number of important factors affecting piston ring performance are examined. They include ring lateral location, constant ring twist (or offset of the ring face profile), bore out-of-roundness, liner temperature distribution and barrel height of the ring face profile. The results indicate that most of these factors have a considerable influence on piston ring performance. Notably, it is shown that ring lateral displacement and bore distortion can have a favourable effect on energy consumption provided blow-by and excessive oil consumption are avoided.