How the wear of cylinder liner affects the cooperation of piston - cylinder assembly of IC engine

A ring pack of modern IC engine consists of at least one compression ring that should guarantee secure a necessary tightness of combustion chamber. A circumferential wall pressure of correctly designed compression ring should be sufficient to achieve a full contact between wall and ring, which means light tightness preventing gas blowby. Lack of tightness is being considered as a principal cause of deterioration of engine performance data including torque instability, and a rapid grow in ring and cylinder wear within the area of blow-by. During engine design process mathematical models are applied which implement analytical and numerical methods of calculation. Analytical methods that were used earlier presented a limited range of application and lower accuracy in comparison to the numerical methods but they allowed achieving approximate results quicker. Taking this into consideration the presented study describes the most important relations between ring geometry and its wall pressure, which were obtained using the analytical methods. Presented formulas facilitate the evaluation of cylinder wear effect on the ring circumferential pressure distribution, especially the change in liner diameter. An attempt of light slits evaluation has been performed as well. The study was supplemented with graphs and calculative example.