Technical Paper
Autoignition of Lubricating Oil from Piston Crown and In-Cylinder Condition on Abnormal Combustion of Supercharged SI Engine
2022-01-09
2022-32-0008
The supercharged spark ignition engine with direct fuel supply system in cylinder (SI engine) has a problem on abnormal combustion at low engine speed. It is called the LSPI (Low Speed Pre-Ignition)[1]. This research focuses on one of the source of abnormal combustion which is the autoignition of lubricating oil from piston crown in cylinder, here especially, frequency of autoignition in cylinder[2,3,4]. In this experiment, the test engine operates without spark ignition as motoring operation. The advantage of this method is to avoid the effect of gasoline dilution[5,6]. Namely, it is able to reveal the essence of abnormal combustion experimentally. The 2 kinds of lubricating oil are tested. The measured data show that the frequency of autoignition in this research is 1/10 of that of lubricating oil scattering from piston crown. The abnormal combustion occurs the frequency of 1 time in each 10000 cycles approximately. The special behavior of the LSPI has been measured.