In recent years, the supercharged spark ignition engine (SI engine) is spread out in the field of passenger vehicle. However, it has a problem of abnormal combustion which is called Low Speed Pre-ignition (LSPI). It is cleared gradually that the character of lubricating oil effects on LSPI behavior. The lubricating oil which has a tolerance for LSPI has been introduced already in the market nowadays. However, cause and mechanism of LSPI occurrence does not clear sufficiently. In previous conference SETC 2018, it was reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown. This paper focuses on frequency of lubricating oil scattering from piston crown.
Two-stroke (2S) engines still play a key role in the global internal combustion engine (ICE) market when high power density, low production costs, and limited size and weight are required. However, they suffer from low efficiency and high levels of pollutant emissions, both linked to the short circuit of fuel and lubricating oil. Low- and high-pressure direct injection systems have proved to be effective in the reduction of fuel short circuiting, thus decreasing unburnt hydrocarbons and improving engine efficiency. However, the narrow time window available for fuel to be injected and homogenized with air, limited to few crank-angles, leads to insufficiently homogenized fuel-air mixtures and, as a consequence, to incomplete combustions. The use of prechambers can be a well-suited solution to avoid these issues.
The supercharged spark ignition engine (SI engine) has a problem of abnormal combustion. It is called Low Speed Pre-ignition (LSPI). The lubricating oil which has a tolerance for LSPI has been introduced already in automobile market nowadays. However, cause and mechanism of LSPI does not clear sufficiently. It has been reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown. This paper focuses on effect of fuel ingredients on autoignition of a lubricating oil droplet about LSPI. On the ignition source point of view, it is important to clear the mechanism of a lubricating oil droplet autoignition in cylinder. This paper will be tried to clear its mechanism fundamentally by using of electric furnace which is heated an oil droplet. As a result, the activation energy E is found for quantitative evaluation of LSPI.