The effect of diesel knock on a turbocharged diesel engine emissions and top compression ring friction

Turbocharged engines with direct injection offer a significant contribution to engine downsizing technology. However, there remain many unsolved and ambitious issues concerning knocking and pre-ignition. Therefore, detailed understanding of the top compression ring lubrication and fuel economy is critical. This paper focuses on the tribological performance of the top compression ring under partially lubricated conditions caused by diesel knock in a turbocharged diesel engine. A mixed-hydrodynamics model was built including multi-phase flow and asperity interactions with realistic boundary conditions. The study shows that frictional power losses in the compression ring-liner contact increased owing to diesel knock and starved conditions in a turbocharged gasoline engine. This finding indicates that the control of knocking combined with the inlet flow conditions can help to mitigate fuel economy and emissions in ring-liner conjunction.