Search Results

A new combustion concept for DISI gasoline engine was developed to achieve superior performances of high power and low environmental load. It realizes a high specific power and a good lean combustion performance simultaneously by utilizing a DI spray jet effectively to accelerate the in-cylinder tumble flow. Injection direction and configuration of the DI spray was optimized for intensification of the in-cylinder flow and high mixture homogeneity, a thin fan-shaped spray generated by a slit nozzle was adopted. As a result, combustion was accelerated by increase of in-cylinder turbulence intensity, and homogeneity of air-fuel mixture was improved. In addition, in-cylinder fuel wall wetting, which causes emission of particulate matter (PM) and oil dilution, was drastically reduced by improvement of the fan-shaped spray.

In this study, a rapid compression and expansion machine(RCEM) with a pancake combustion chamber was designed to investigate fundamentally on the knocking phenomena in spark ignition(S.I) engines. This RCEM is intended to simulate combustion in an actual engine. The homogeneous pre-mixture of n-pentane and air was charged into a quiescent atmosphere of the chamber. Then, the combustion field become simpler in this machine than it in a real S.I. engine. Also, the combustion phenomena, that is a cylinder pressure history, the behavior of flame propagation and so on, with high reproducibility are realized in this machine. The phenomena caught in this experiment were so-called low speed knocking. And, this knocking characteristics such as a knock intensity and a knock mass fraction were revealed by the cylinder pressure analysis varying the charge pressure and the equivalence ratio of the mixture, a compression ratio and an ignition timing.