Formation of Soot Particulates in the Combustion Chamber of a Precombustion Chamber Type Diesel Engine

To clarify the formation processes of soot particulates in the combustion chamber, we sampled the gas during combustion in a precombustion chamber and a main chamber using an electromagnetic sampling valve, and made a gas analysis by gas chromatography, examined the soot concentration, and size distribution and dispersion of soot particulates with a transmission electron microscope.

The following results were obtained: (1) In the prechamber soot particulates form at the period of rapid combustion in the initial stage rather than the end of the diffusion combustion. (2) Soot particulates which were formed in the prechamber were introduced to the main chamber, and a part of the soot particulates were burned. (3) Soot particulates formed at the initial stage of the combustion process exhibited a tendency to become smaller by oxidation. (4) If the oxygen concentration in the combustion chamber is above 5%, the combustion of soot particulates take place.