Application of Air Assisted Direct Fuel Injection to Pressure Charged Gasoline Engines 2002-01-0705
With the ever increasing desire to improve the thermal efficiency of the internal combustion engine, the combination of gasoline direct injection with engine downsizing and intake charging may offer the greatest potential for maximizing the efficiency of these engines. Although the comparative benefit of direct injection alone may be reduced when compared to the downsized and charged engine directly, the combination of the two technologies has the potential to offer substantially larger total fuel consumption reduction in automotive applications than either technology independently.
The Orbital developed air-assisted spray guided combustion system has unique properties which are shown to be desirable given the increased demand of boosted engine operation. The decoupling of fuel metering and direct injection events promotes large dynamic range of fuel metering and, when combined with variable fuel metering differential pressure, results in turn down ratios in excess of 24 to 1. As well, the spray guided combustion system, with the direct injector aligned with the cylinder bore axis, enables injection timing which is not dependent on piston position. This results in the ability to operate the engine with boosted inlet conditions at higher part load, leading to further reductions in fuel consumption compared to naturally aspirated operation without increasing engine out emissions levels.