On fuel and deposits. Part 1

Introduction (problem statement and relevance). Generally, deposits or sediments are an inevitable consequence of processes of mixture formation and combustion in the engine cylinder, complex physical and chemical processes with the hydrocarbon “participants” of this process – fuel and oil. There is no consensus in the scientific community regarding the role of these participants. Some researchers consider the “fuel” factor to be the predominant one, the others have no less reason to think it is the “oil” factor. Meanwhile, understanding the nature of formation of deposits, both the “cold” ones (in the intake path) and the “hot” ones (in the combustion chamber) is the most important condition in order to determine the methods to combat this negative phenomenon, in particular, and due to development of scientifically grounded requirements for qualitative characteristics of both fuels and oils. The relevance of the issue increases due to the fact that the existing methods of fuel testing based on foreign procedures with application of foreign reference engines become almost inaccessible following refusal of a number of the manufacturers of reference engines for standardized testing to provide further technical support caused by phasing-out of models of these engines. Moreover, during the period of common confusion in the European engine-building and uncertainty over prospects of the automotive industry on the whole, no solution was taken either for the procedure or for the new reference engine for the direct fuel injection engines increasingly dominant in the market of gasoline engines. The vacuum created is occupied by unapproved procedures with application of engines having different designs. In such conditions, correct comparison of test results obtained in different laboratories becomes almost impossible, while the results themselves lose their practical value. The purpose of the study and its practical significance consist in study of the mechanism of deposits formation in spark ignition engines and development of methods to test fuels for tendency to form certain types of deposits. Development of domestic scientific research methodological and experimental basis for engine testing of fuels and oils for deposits formation tendencies. Scientific novelty and results. The experimental studies, and the thermal gravimetric ones in particular, convincingly prove the hypothesis of domination of the fuel factor in formation of “cold” deposits on the intake valves. It has been experimentally shown that the results of testing following the new procedures adequately reflect the efficiency of using detergent additives.