Federal-Mogul Powertrain has developed a new piston ring for use in commercial vehicle diesel engines that enhances gas sealing capability by stabilising ring dynamic motion and homogenising oil film. The running surface profile of the new eLine rings for use in the second groove has been designed to distribute oil more evenly around the cylinder bores and to modify the running face area for reduced gas pressure force. This results in enhanced engine efficiency, increased robustness and lower emissions. Bench tests with eLine in different diesel engines have shown a significant reduction in blow-by of up to 20%, which converts directly into either an increase in mean effective pressure or a decrease in fuel consumption.
“eLine is the first commercial vehicle piston ring technology that distributes oil circumferentially in a consistent layer,” explained Dr Steffen Hoppe, director, Technology, Rings and Liners, Federal-Mogul Powertrain. “The design compensates for localised surplus oil drops, protects against local oil film breakdown, supports low oil viscosity strategies, improves the sealing of combustion gases and reduces wear. The specific running surface profile has also been designed to prevent radial ring instabilities, which are becoming more common due to the industry trend for increased peak combustion pressures.”
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Rings used in the second groove of commercial vehicle engines are predominantly designed with a tapered running face profile. These can struggle to maintain a homogeneous oil film in sub-optimal conditions, such as bore distortion or oil supply issues. The tapered profile also provides a comparably large running face area, which can result in radial ring instability when the pressure between the inner and outer diameter of the ring becomes imbalanced.
The eLine piston ring has a circumferential groove towards its lower side, allowing surplus oil to be retained below the ring. The oil in this groove reservoir creates a circumferential pressure difference that generates controlled oil flow around the bore as the piston reciprocates, improving the uniformity of the oil film. The hydrodynamic function of the running surface profile has been developed in a way that allows for a reduced area for gas pressure force towards the upper side of the ring.
Federal-Mogul Powertrain’s eLine piston rings are currently with customers for validation in preparation for a short-term market introduction.
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