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Worldwide emissions standards are becoming increasingly rigorous, and this leads to more complex engine demands. Several new PCU (Power Cell Unit) technologies are being applied to cope with these demands. This means engine parameters are changing, e.g. higher EGR (Exhaust Gas Recirculation) rates, higher PCP (Peak Cylinder Pressure), lower viscosity oils, higher oil contamination and soot. Therefore the operating conditions for the bearings have drastically changed, leading to an environment prone to seizure occurrences. There is a clear demand for seizure resistant bearings motivated mainly by the increased engine complexity described above. Therefore for HDD (Heavy Duty Diesel) applications the PCU robustness should not be compromised also in terms of wear and fatigue resistance. The polymeric coating developed by MAHLE was applied over a sputtered layer and has demonstrated to be a suitable solution to attend to the application demands.

The increasing demand for engines with higher efficiency, reduced fuel consumption and high power density is driving the future engine technologies in the direction of downsizing and reduction of number of cylinders, especially for Otto engines. Specifically the Power Cell Unit (PCU) components are of extreme interest due to its potential for weight and friction reduction. To cope with these demands a new lightweight connecting rod design for flex fueled engines was developed. The combination of thinner web thickness and bushingless small end (coated and profiled), through the optimization by Finite Element Analysis (FEA) simulation, enabled on the new lightweight design a weight reduction of 25% maintaining safe connecting rod fatigue limits in a studied flex fueled engine. The connecting rod bearings were evaluated using Elasto-Hydrodynamic Lubrication (EHL) simulation, and demonstrated suitable results. The connecting rod material selected was the premium 46MnVS6 forged steel.

Lead free bronze substrate associated with a lead free electroplated coating has been the standard bearing material technology for medium size Diesel engines. However the increasing engine demands are driving this technology to the limit. With the increase of Peak Cylinder Pressure (PCP) to improve power density and reduce CO2 emissions, the bearings are subjected to higher loads which usually reduce their durability. The new operating conditions are more prone to wear and eventually scuffing occurrences. Therefore materials with higher scuffing and wear resistance without a significant cost increase are demanded. To meet the requirements of highly loaded Medium Duty Diesel (MDD) applications, a lead free material based on a high resistant bronze substrate associated with a polymeric coating was developed. The polymer is sprayed onto the substrate and cured on a high temperature to provide performance improvement and adequate thickness control.