Characteristics of Injector Nozzle Carbon Deposits in Diesel Engine

The distribution area, shape and size of the injector nozzle carbon deposits in a diesel engine were analyzed by optical electron microscopy.The microstructure and elemental composition of the carbon deposits were analyzed by scanning electronic microscopy and energy dispersive spectroscopy, respectively.The results show that the nozzle carbon deposits can be divided into three types which are the exit carbon deposits, large internal carbon deposits and carbon deposits on the inner wall of the hole according to the distribution area.The exit carbon deposits, roughly distributed in an arc shape around the exit, take the largest amount with relatively regular shape.The internal carbon deposits are less amount with smaller size and irregular shape.The carbon deposits on the inner wall of the hole are uniformly distributed on the wall surface, but the carbon deposition amount is not significant, resulting in an increase in wall surface roughness.It is found from the microscopic morphology that the carbon deposits on the bottom layer are spherical, the spherical particles are closely arranged, the structure is complex.The surface layer carbon deposits are integrated into one piece, whose structure is firm and there is no obvious granular shape.The carbon deposits are mainly composed of C and O elements.There are also a small amount of Si, Fe, K, Mo, Cl, Cr elements, in which Fe, Mo, Cr may be come from the wear of the cylinder liner piston particles adsorbed in the carbon deposit with the lubricating oil and Si, K, Cl elements may be from the oil and oil additives. © 2019, Editorial Office of the Transaction of CSICE. All right reserved.