| 초록 |
In this study, in an attempt to analyze the effect on combustion and the exhaust characteristics of the ultra-high pressure fuel injection system in the gasoline direct injection(GDI) engine, the conventional fuel injection pressure of 350 bar and the 500 bar fuel injection system were compared. To improve the delay of the needle behavior due to the fuel pressure of 500 bar, a non-magnetic ring was inserted so that magnetic force loss would not occur, unlike the low-pass method of a magnetic force transfer of the existing injector. In the process of engine evaluation, indicated mean effective pressure(IMEP) and brake specific fuel consumption(BSFC) results based on load were compared, while combustion speed and loss were calculated by additionally measuring engine combustion pressure. As a result, in terms of combustion speed and loss, the 350 bar system showed better results under the low load condition, but, as the load increased, the 500 bar system showed faster combustion speed and less loss. Lastly, in the case of exhaust gas emission characteristics, when the exhaust results for the 350 bar and 500 bar fuel injection systems were compared, NOx emission showed a higher emission at the 500 bar condition, compared to the 350 bar, as the load condition increased. Conversely, in the case of CO emission, lower emission could be confirmed at 500 bar condition as the load condition increases. This result can be considered as influencing combustion temperature according to the combustion rate. Furthermore, in the results of particle number(PN) emission, high PN reduction was confirmed by the application of an ultra-high pressure injection. |
