P-L-N 디젤 噴射系의 噴射特性에 미치는 燃料캠의 影響에 관한 硏究

Abstract

In the study of diesel engines more efforts have been made on the lower fuel consumption and the reduction of exhaust emission. Especially, the atomization and injection rate in related to the exhaust gas to be minimize its harmful components. From this point of view many investigations have been carried out to solve this problem. Those are the studies on improving the atomization characteristics by higher injection pressure and shortening the injection duration by the higher injection rate. In diesel engine the fuel and air mixture which is accumulated in combustion chamber during the ignition delay is studied. High temperature and high pressure gas intend to increase the engine noise, vibration and nitrogen oxides. So shortening the ignition delay and lower injection rate in the initial phase of injection are demanded. At the end of injection, falling of pressure in injection system and combustion chamber make the atomization worse. Therefore the fuel injected during the end phase of injection does not burn completely and unburned gas of deposites are accumulated at the tip of injection nozzle. Therefore a ideal from of injection rate is the higher rate of pressure drop during the end phase of injection and lower injection rate during the initial phase. In this study, in order to investigate the influence of cam profile on the injection rate, the characteristics of injection in P-L-N ( pump-line-nozzle ) diesel injection system was simulated. 6 type of the profiles of fuel cam are used for simulation. As far as the characteristics of injection are concerned, maximum injection pressure, maximum injection rate and the injection rate of initial phase, end phase were analyzed. The mathematical model of injection system and the computation results, were verified by experimental results. Simulation results showed that maximum injection pressure, maximum injection rate, injection quantity and pressure drop in the end phase were proportional to the velocity of fuel cam during the effective stroke.