Lubricating Oil Droplets in Cylinder on Abnormal Combustion in Supercharged SI Engine
The supercharged spark ignition engine has a problem of abnormal combustion at low speed and high load operating condition. This paper focuses on the sauce and mechanism of the abnormal combustion, namely, the behavior of lubricating oil droplets in cylinder, ring crevice, piston crown and ring gap. The experimental approach and the numerical analysis have been carried out. The two experimental approaches namely direct photography by high speed camera and measurement of scattering oil quantity at low speed condition have been tried. The photographs which is in engine operation show, 1st The oil droplets from ring crevice scatter every reciprocating motion and the diameter of oil droplets is between 0.10mm and 0.30mm. 2nd The oil droplets from piston crown has three steps as follows, firstly, the lubricating oil which reaches piston crown continues to accumulate, secondly, the accumulated lubricating oil scatters by the reciprocating motion.