Improving the performance of parts of the cylinder piston group of marine diesel engines

Abstract

For the repaired engine installed on the vessel, in order to ensure its normal operation, it is necessary to run-in. This operation consists in the running-in of rubbing surfaces to ensure the necessary surface roughness, surface shape, and an increase in the contact area of the mating surfaces. The result of proper running-in is considered to be the efficient operation of the engine, in which all engine parameters are stable, such as coolant temperature, exhaust gas temperature, fuel consumption, oil consumption. In most cases, the details of the cylinder piston group, especially the piston rings, which operate under the most extreme conditions, are responsible for all the listed engine parameters. New piston rings, with an ideal shape inserted into the piston groove of the piston, cannot ensure a tight fit to the cylinder surface during movement, in this regard, gaps appear in some places that violate the tightness of the combustion chamber. Elimination of these gaps is one of the main tasks of running-in of the mating surfaces. The main factors affecting the duration of the run-in are the macrogeometry of the piston rings, the profiles of the working surface of the piston ring and cylinder, the roughness of the surfaces, the running-in modes, lubrication and maintenance coatings. Analyzing scientific research in this field and relying on their experience, an algorithm of running-in works was formed, which was subsequently tested on engines. The final stage of the research in this direction consisted of the analysis of the positive results of the experiment and on its basis formulas for engines of different turnovers were proposed.