GDI용 인젝터를 이용한 분사 조건별 분무형상의 특성

Abstract

Recently GDI(Gasoline Direct Injection) engine is spotlighted to achieve higher thermal efficiency under partial loads and better performance at full loads. To realize these, it is essential to make both super-lean stratified combustion and homogeneous combustion. When compared to PFI(Port Fuel Injection) engine, GDI engine needs more complicated control and optimal design with piston cavity. In addition, spray pattern must be optimized according to injection timing because ambient pressure in combustion chamber is also varied. Thus spray structure should be analyzed in details to meet various conditions. In this experimental study, system of spray visualization was built for coping with variable ambient pressures in high pressure chamber and the spray characteristics were investigated for a few sample GDI injectors. To make clear spray pattern, the images for vertical and horizontal sections were taken as fuel injection was processed. With an increase at the ambient pressure in chamber, the tip penetration and spray diameter is inclined to decrease due to rising resistance caused by the drag force of the ambient air. These results provide the information on macro spray structure and design factors for developing GDI injector.