Gasoline direct injection-challenges

Abstract

The demand for reduced fuel consumption and low-emission spark ignition engine is rising, in response to concerning energy conservation and preservation of the global environment. Air-fuel mixture formation plays a significant role in controlling exhaust emissions and engine efficiency. The primary purpose of fuel injection system is to provide the engine with correct air-fuel ratio according to engine operating condition. Fuel injection system of spark ignition engine has developed in last thirty years monotonically from the carburetor to throttle-body injection, and then to port fuel injection (PFI). Although, the current port fuel injection technology is highly evolved, but it is difficult to achieve further stringent emission norms and demand for lower fuel economy. Gasoline direct injection (GDI) system is a promising next generation of technology for the automotive engine to improve fuel economy, performance and emissions control. GDI engines are characterized by injecting fuel directly into the combustion chamber at high pressure during the compression stroke. Air-fuel mixture formation takes place inside the combustion chamber as in a diesel engine. GDI engine offers a significant potential for improving the fuel economy and reduction of exhaust emissions from spark ignited engine, while maintaining or improving the high specific power output of current PFI engines. GDI engines has several potential advantages over PFI system, however, it does have a number of inherent problems that need to be address. These constraints are controlling the stratified charge combustion over wide range of engine operation, complexity in injection strategy for seamless load changes, injector deposits, increased particulate emissions etc. In this paper, several difficulties associated with GDI development and its probable solution will be discussed.