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Influence of engine load on piston ring pack operation of an automotive IC engine

Wolff Andrzej, Koszałka Grzegorz

Combustion Engines

2022

R. 61, nr 3

88--94

A piston-rings-cylinder (PRC) assembly determines the blowby, engine oil consumption, and friction and wear processes accompanying the system's operation. Thus, it is crucial for the whole IC engine efficiency and lifetime. A lot of research effort is put into increasing the performance of this complex and highly dynamic system. Advanced, comprehensive models play an important role in understanding and improving the PRC system. In the presented work, the effect of load on the operation of the ring pack of an automotive gasoline engine is analyzed. A comprehensive model that covers the gas flow through the crevices of the PRC system, ring displacements in the groove, and ring lubrication was used for this analysis. The results of the simulations show that the local thickness of the oil film, especially near the piston top dead center is compared to the height of the combined surface roughness of a cylinder liner and piston rings, and friction-related asperity contact strongly increases as the engine load increases. The simulations also show that the engine load affects the axial displacements of the rings in the grooves but practically does not affect the thickness of the oil film left by the ring pack on the cylinder liner.

Comparison of fuel consumption and exhaust emissions in WLTP and NEDC procedures

Koszałka Grzegorz, Szczotka Andrzej, Suchecki Andrzej

Combustion Engines

2019

R. 58, nr 4

186--191

Fuel consumption achieved in the New European Driving Cycle (NEDC) could be 50% lower than the fuel consumption in real driving conditions and in the case of emissions of regulated toxic compounds the differences could even be much greater. In order to bring the results achieved in official tests closer to real life figures, the European Commission introduced in 2017 the Worldwide Harmonized Light Vehicles Test Procedure (WLTP), which replaced the NEDC. In this article the results of fuel consumption and exhaust emissions for 3 cars fitted with engines of the same displacement but with direct and indirect gasoline injection, determined according to the NEDC and WLTC were presented. The results show that the effect of driving cycle on the fuel consumption is equivocal - for one car, fuel consumption was higher in the WLTC; for the other one in the NEDC; and for the third one, fuel consumption achieved in both driving cycles was practically the same. Emissions of regulated exhaust compounds, except for THC, obtained in the WLTC were higher than in the NEDC driving cycle.