Analysis of Tribological Performance of a Piston Ring Pack

Abstract

Performance analysis of a piston ring pack is presented in this investigation with the objective of studying the behavior and interrelationships of key engine parameters such as oil consumption, blow-by/blow-back, power loss and wear loads for typical operating conditions. The analysis is based on an integrated methodology addressing the various physical phenomena associated with ring packs including (a) ring dynamics for axial and twist motions within the grooves to determine flow paths for gases, (b) inter-ring gas dynamics for blow-by and blow-back behavior, (c) mixed lubrication at the ring face-liner conjunction for friction considerations and radial ring dynamics, and (d) oil transport for distribution of lubricant along the liner. Relevant output from each of these phenomenological models such as instantaneous values of (i) inter-ring flow areas, (ii) gas blow-back, (Hi) volume of oil within inter-ring regions, (iv) oil accumulation at top ring's leading edge and (v) liner oil film distribution are utilized by the oil consumption models which enable the calculations from the various consumption mechanisms (due to throw-off, entrainment and evaporation). Additionally, wear loads on the ring faces and liner are calculated based on contact pressures due to mixed lubrication at the ring face-liner interface. Included in this investigation are results from a series of studies undertaken to analyze the behavior of the aforementioned engine parameters over a range of speed and load conditions. Presented as a Society of Tribologists and Lubrication Engineers Paper at the STLE/ASME Tribology Conference in Orlando, Florida, October 11–13, 1999