Characterization of Automotive Engine Deposits

Abstract

It is well-known that the deposits accumulated excessively in automobile engine affect the exhaust emission and drivability. Accordingly, the accumulation of the deposit is one of the serious problems to be solved for developing high performance engines. We have been studying the analytical methods of the deposit formation in order to clarify the cause of the deposit accumulation. The methods introduced in this documentation are as follows. First, the deposits were classified into two types of seven components by the differences in their formation origins and environments; four components from fuel, three components from engine oil. Next, the characteristics of these components were determined by four kinds of analytical techniques, and the seven components could be distinguished from one another by four kinds of analytical indexes; chemical structure, elemental composition, thermal gravimetric property and solubility. Furthermore, by using these indexes, the deposit formation factors such as formation origins, formation environments and formation routes could be estimated. In addition to the above methods, the key points to keep in mind for the deposit countermeasure were also described.