연료 레일 체적이 가스분사 특성에 미치는 영향(1) - 분사 유량

This study is to investigate the fuel injection characteristics according to fuel injection pressure, injection pulse width and engine speed in a gas fuel supply system. A current conversion kit consisting of 5 cc volume fuel rail and injector is mainly used. In addition, the fuel rails with the volume of 100, 200, and 435 cc are compared to verify the fuel rail volume effect. Compressed air was used as an analogous fuel, and sequential injection was performed using an injector driver that controls injection pulse width. The fuel injection quantity was measured using water transposition method. The injection pressure, injection duration, and engine speed were set in four steps, respectively, considering the actual engine operation. For the most part, the higher the fuel pressure and the longer the injection period, the higher the injection flow. In contrast, the higher the engine speed, the lower fuel quantity. If the natural gas was used as the fuel at 6,000 rpm wide open throttling operating condition of the 2,000 cc 4-cylinder engine, at least 53 cc of single injection per each cylinder was required. The minimum injection quantity should be 5 cc or less for smooth fuel quantity control. At all conditions the minimum injection quantity was much greater than 5 cc. At full load conditions, the fuel injection pressure of 1.5 bar did not meet 53 cc. If the injection pressure was increased, the injection quantity became excessive nonetheless. On the other hand, the volumetric effect was visible only in the very difference such as between 5 and 435 cc. When the volume of the fuel rail was increased, it was advantageous in securing a precise fuel metering characteristic and could satisfy maximum injection requirement. However, the minimum injection requirement was still excessively great.