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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.

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.

With the implementation of Proconve P7, several challenges were faced regarding the integrity of the Power Cell Unit (PCU), which comprehends pistons, rings, cylinder liners, pins, conrods and bearings. The technologies of reducing NOx affect directly the performance of these parts. The systems focused on EGR (Exhaust Gas Recirculation) provoke a higher level of soot contamination in the oil, which creates to all the PCU an abrasion mechanism that leads to the increase of wear load. The systems focused on post treatment of the exhaust gas enables to reach higher PCP (peak cylinder pressure) and higher temperature of combustion. Such conditions are also critical to the PCU combustion, which needs to increase resistance to higher mechanical and thermal loads. Using the experience of Europe and NAFTA some expectations about the environment conditions of Heavy Duty Diesel (HDD) engines after Proconve P7 can be discussed.

Several cases of rod bearing shells assembled in highly loaded engines have been reported to show premature wear of the sliding surface, more specifically the electroplated lead-tin overlay. To understand these phenomena and overcome such occurrences, an analytical method has been developed to simulate the operation of specially designed journal bearings featuring circumferential profiling of the sliding surface. The resulting computer program solves the Reynolds equation taking into account a non-circular bearing surface, thus allowing for a customized design which extends operational component life through minimum oil film thickness (MOFT) increase and peak oil film pressure (POFP) and bearing back temperature (BBT) reduction. Theoretical results show an effective way to prevent premature wear.