Multi-Stage Injection Control for Super Ultra Low Emission Vehicles

Direct Injection Gasoline Engine has been developed to improve the performance and the fuel consumption of engine. On the other hand, the issues such as wall-wetting, HC at low load condition and low NOx combustion are remained. Spray-guide concept is employed to get a high-torque and to improve fuel consumption under low emission performance at the same level as a port injection engine. Multi stage injection system (MUSIC) can reduces emission, and provides better performance and fuel economy than single injection. As generally known, the rapid catalyst warm-up using ignition retarding has an effect on emission reduction during engine start-up mode. In this paper, spray-guide and multi stage injection system are applied to improve a rapid catalyst warm-up as a technology to reduce emissions for meeting SULEV category of California emission standard. For the measurement of the mixture characteristics in the cylinder, Flame Ionization Detection analyzer (FID) is used. The characteristic of mixture controlled by the injection ratio and timing of MUSIC was optimized on the basis of FID analysis.