Overview

IntroductionIn the recent years, heavy emphasis on reducing the BSFC while meeting the stringent emission normsOver the past two decades, attempts have been made to develop an internal combustion engine for automotive applications that combines the best features of the SI and the diesel engines.The objective has been to combine the specific power of the gasoline engine with the efficiency of the diesel engine at part load.Research has indicated that a promising candidate for achieving this goal is a direct-injection, four-stroke, sparkignition engine that does not throttle the inlet mixture to control the load.In this engine, a fuel spray plume is injected directly into the cylinder, generating a fuel-air mixture with an ignitable composition at the spark gap at the time of ignition.This class of engine is designated as a direct-injection, stratified-charge (DISC) enginePotential benefits of GDI over PFIFuel System requirementsFuel injector characteristicsFuel spray characteristicsThe fuel injection system in a GDI engine is a key component that must be carefully matched with the specific in cylinder flow field to provide the desired mixture cloud over the entire operating range of the engineA well-atomized fuel spray must be produced for all operating conditionsA GDI fuel system needs to provide for at least two, and possibly three or more distinct operating modes.Flow structureFuel air mixingCombustion chamber geometryEngine operating modes and fuel injection strategiesTypes of combustion chambers

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