GASOLINE DIRECT INJECION
ABSTRACT:
The presently used technology for gasoline engine is the port fuel engine technology (MPFI is multiport fuel injector). This technology, although extremely refined has reached a limit beyond which its efficiency and performance be improved. This is because there are a few limitations inherent to this technology like throttled like throttled charge and lack stratification.
Stratification is the basis of the gasoline direct injection engine and hence it is also called as direct injection stratified charge engine. The concept and achievement of stratification is explained in the paper. For the achievement of charge stratification direct injection of fuel into the combustion chamber is a requirement. Thus, in gasoline direct injection, the fuel is directly sprayed into the combustion chamber. There are again various modes of doing so much as wall guidance or spray guidance of fuel and narrow spacing or wide spacing of injector. These are explained in the paper.
Another feature of the GDI engine is the elimination of throttling losses. This feature is similar to the diesel engine which was the only technology to make use of direct injection before GDI and provides many advantages over PFI. These advantages of direct injection were known since a long time and a lot of manufacturers attempted to develop GDI. A brief history of the development of GDI engines has been given in the paper. However the sophisticated equipment like high pressure pump required for GDI have been made available only recently to the mass production of GDI.
The specification and engines used by a few presently mass produced GDI engines are given in the paper. Also an account of the fuel injection system and strategies is given in the paper. Thus by he end of paper, an overall trend of automotive industries can be observed which start of with the limitation s of the PFI engines and challenges for the next generation technology i.e. GDI engine; prorogates with the development of GDI engines and concludes (but does not terminates) with the high compatibility of GDI with other modern technologies of impending future.
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