New Piston Ring Concept by Winterthur Gas & Diesel for Optimized Fuel Consumption

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Winterthur Gas & Diesel (WinGD) reveals a groundbreaking new piston ring concept for optimized fuel consumption. Friction reduction cavities in the piston ring utilize entrapped air for lubrication and save weight.

Within the constant struggle to optimize fuel consumption of marine diesel engines, WinGD revealed their latest technological achievement: A new piston ring design enabling a completely new piston running tribological system which achieves significant fuel savings due to friction reduction and unprecedented weight saving particularly for masses exposed to high acceleration and speeds.

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Caption 1: CAD depiction of the new FRC piston ring design (gas tight top ring shown).

A key element of the new tribology is the new piston ring design, which relies on the well-known and proven piston ring design used in WinGD 2-stroke marine diesel engines in vessels all over the globe. However, unlike conventional piston rings, the running surface has been modified with friction reduction cavities (FRCs) which not only reduce the amount of surface needing lubrication, but further reduce friction by utilizing the air entrapped in the FRCs for lubrication.

Compared to conventional cylinder lubrication oils of the SAE 50 grade having kinematic viscosities of 16.3-21.9 cSt at 100°C, the utilization of FRC entrapped air reduces kinematic viscosity to a mere 1.8 cSt at 100°C. This yield tremendously reduced friction coefficients for the piston ring/ liner system at ever-increasing mean piston speeds, while acting as an ideal insulation material to avoid unintentional heat transfer.

The manufacturing costs for FRC piston rings will be slightly higher than for conventional piston rings due to additional manufacturing steps of machining the cavities into the piston ring running surface. However, the material removed in this process contributes directly to the overall weight saving of up to 40% in comparison to traditional designs. When considering the high accelerations and speeds of the piston rings during engine running, the resulting lower masses in motion lead to additional fuel savings. Reliability and time between overhauls are not compromised, in fact the lower reciprocating masses are anticipated to lead to lower wear of the piston ring groove, resulting in longer times between overhaul or reconditioning of the piston crown.

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Caption 2: Picture of gas tight FRC piston top ring in comparison to standard execution.

The achieved savings in fuel consumption and overhaul costs strongly outweigh the higher component price within a minimum duration of typical vessel operation in the field.

Additionally, lube oil savings may be realized from FRC piston ring development due to the partial replacement of lubrication oil with entrapped air. First indications are very promising and detailed investigations are ongoing.

Once again WinGD is pushing the boundaries for maximizing fuel efficiency in 2-stroke low-speed marine diesel engines to the benefit of the marine industry.

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