Experimental study of cylinder-piston group resource of marine ICEs using lubricant compositions

The paper presents the results of a model experimental study of the resource of the mating parts “piston ring - cylinder liner” of a marine diesel engine. A medium-speed trunk engine 6Ch36/45 of medium boost was chosen as a real diesel engine under study. An experimental study was carried out by using an antiwear additive containing molybdenum diselenide MoSe2 to a lubricating oil similar to that used in a circulating lubrication system. The studies are supplemented by a calculation model of the resource of the mating parts “piston ring - cylinder liner” followed by a comparison of the calculated values with the obtained experimental data. The following parameters mainly influence the resource of the selected tribological mating: the contact pressure of rubbing surfaces, the additive concentration in the oil, the shelf life of the additive before it is added to the oil without mixing it. The life tests of the parts of the “piston ring - cylinder liner” mating of a marine diesel engine made it possible to identify the effective concentration of the additive in oil by the formula Ci = 0.5÷1.0 vol. %. The resource of parts of the friction pair “piston ring - cylinder liner” increases by 1.28÷1.67 times in relation to the standard parameters of the 6Ch36/45 diesel engine. Non-compliance with the storage conditions of the additive before adding it to the oil can reduce the resource performance relative to the normative standards for of this diesel engine by 1.7÷3.45 times. It has been proved that the developed mathematical model of the service life of the parts that make up the tribological mating “piston ring - cylinder liner” has a high convergence (relative error 0.5÷5%) with the results of the experiment on the physical model of the studied friction pair “piston ring-cylinder liner”. There has been studied the influence of the volume concentration Ci of an antiwear additive on the calculated and experimental indicators of the marine diesel engine resource, the optimal value of which should not be lower than 1.0%, while the value of the contact pressure in the friction pair is up to 1.0 MPa, the time of preliminary storage of the additive is no longer than 36 hours. It has been recommended to apply the developed mathematical model to estimate the resource of the friction pair “piston ring - cylinder liner” for high- and medium-speed internal combustion engines.