Downsized engines are considered one major technical trend to
attend the demands for CO₂ and fuel consumption reduction. Usually
this engine configuration consists of displacements between 0.9L
and 1.2L with 3 or 4 cylinders, usually associated with turbo
charge. The increased load due to high gas pressures and power
density may affect the PCU components, specially the piston
rings.
This work reviews the ring pack used on the current downsized
engines from European and NAFTA OEMs. The different ring designs
and materials used on downsized engines are discussed. The specific
challenges that those engines present to piston rings and the
available alternatives are discussed.
An extreme low friction, under development, ring pack was tested
in a 1.2L Turbo downsized engine. With low friction, a low
tangential force ring pack, the main issue was control of Lube Oil
Consumption. The use of an innovative Oil Control Ring design
enable the ring pack to present similar levels of Lube Oil
Consumption than the current production with almost 60% reduction
on the ring pack load.