Research Trend of Friction Loss Reduction in Internal Combustion Engines

According to the International Energy Agency (IEA), it is predicted that internal combustion engines (ICEs) will function as important power sources for plug-in hybrid vehicles or hybrid electric vehicles until 2050. To improve ICE performance, the utilization of technology that is focused on reducing heat loss and friction loss is critical. To achieve friction reduction, the application of low-viscosity oil for pistons and the realization of lower coefficients of friction between piston rings and cylinders serve as effective boundary conditions. The application of these conditions generates high seizure resistance as well. Many research and evaluation studies have been performed using the single cylinder floating liner engine method. However, there are no engines for which a quantitative evaluation is possible, so the causes behind friction losses are difficult to determine, and a mechanical analysis is difficult to perform. In this study, the trend of power sources analyzed by the IEA, prediction of the reduction in the coefficient of friction in automobiles by the European research center, and the concepts of each engine sliding surface condition are introduced. In addition, the difficulty of quantitative evaluation is also described, and the importance of a standard for the floating liner engine is explained