Abstract
Since late 1980s, high pressure fuel injection technologies for diesel engine have been developed as one of the effective measures for achieving gradually tightened exhaust emissions target. While demand for improving exhaust emissions is still strong, there also have been much stronger demands for lower engine cost, lower fuel consumption, and lower GHG emissions in recent years. Under these circumstances, it should be necessary to predict future injection pressure target from not only exhaust emissions, but energy balance view point. As for the increase in BMEP resulted from downsizing and/or down-speed ing, higher injection pressure is necessary to increase injected fuel quantity within the limited injection duration. However, for the simultaneous improvement in both exhaust emissions and fuel consumption under such high temperature and high density conditions, higher injection pressure should be combined with optimized injection rate profile, nozzle specification, cavity shape, and in-cylinder flow to reduce energy losses.
