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A stoichiometric 2.0L turbocharged DISI engine is developed based upon the Theta 2.0L NA engine. The engine is intended to be installed in a midsize sedan as a downsizing concept, targeting to improve the fuel efficiency of the vehicles installed with the V6 3.3L engines while maintaining the performances. The base 2.0L engine is modified to accommodate the 4∼12MPa direct injection system with the multi-hole injectors and the intake/exhaust variable valve timing (VVT) system. The turbocharger is carefully matched so that the specific power over 85kW/L can be achieved while the maximum torque reached at 2000RPM. The fuel efficiency of the target vehicle was improved significantly due to the reduced friction and pumping losses compared to the vehicle equipped with the V6 3.3L engines. Various advanced gasoline turbocharger technologies for improving the transient performances are evaluated.

In order to investigate the effects of a DC electric field and its polarity on the knock intensity in a spark-ignition engine, an experimental study was carried out with a rapid compression machine. To get a good understanding of the effect of an electric field on knocking combustion, the high-speed direct photographs were taken. The ionization current measurements were also carried out using the electrode as an ionization probe The major findings of present investigation of the effects of DC electric fields on the knocking combustion process in a spark-ignition engine could be summarized as follows: It was clearly indicated that the knock intensity decreases with the increase of the electric field regardless its polarity. The knock intensity was strongly dependent upon the burned mass fraction at the onset of the end-gas autoignition, and decreased as the burned mass fraction increased.

In HMC, the fundamental research on the hydrogen fueled engine and vehicle has been carried out. For this engine, solenoid driven injector is used to supply gaseous hydrogen into the cylinder and various operating parameters have been changed to study the combustion characteristics of hydrogen. After these experiments on engine, hydrogen fueled vehicle has been constructed and it is controlled by ECU. The amount of emission from the hydrogen vehicle with stoichiometric operation is less than 1/3 of the ULEV legislation.

The flow characteristics such as flow coefficient and swirl ratio in cylinder were measured at steady-state condition by using a steady-state flow measuring system which consists of an impulse swirl meter and a viscous flow air meter. Effects of the in-cylinder swirl on the emissions (NOx, THC), BSFC, MBT, and lean mixture limit (LML) were investigated by using single cylinder research engine with a helical intake port. The combustion pressure in the cylinder was measured to analyze the combustion duration (such as the initial burn duration and the main burn duration) and COV of IMEP which have an effect on LML. By generating the in-cylinder swirl, the combustion duration is remarkably decreased, while the emissions and BSFC are increased. The lean mixture limit is increased with the in-cylinder swirl ratio. In the case of high swirl ratio (Rs=2.48),the lean mixture limit is increased by 3.3 with optimized fuel inject ion timing.

The purpose of this paper is to closely examine the influence of the behavior of fuel mixture in the intake manifold on combustion characteristics, performances of engine output and exhaust emission by using a 4-stroke spark ignition engine. In case of removing the liquid film fuel flowing on the wall of the intake manifold and of not removing it, the values of combustion characteristics such as the heat release delay, the combustion delay, the rate of heat release, the burned mass fraction and the maximum combustion pressure were obtained from the analysis of pressure indicator diagram. And then, the values of engine performance and concentration of exhaust gas were obtained.