Technical Paper
Development of a High Fuel Economy and Low Emission Four-Valve Direct Injection Engine With a Center-Injection System
2004-10-25
2004-01-2941
The authors developed a direct injection stratified charge engine employing a center-injection system in which a high-pressure fuel injector is located in the center of the combustion chamber and the fuel spray is vertically injected into the cylinder toward the piston bowl. Stratification is controlled by the fuel spray characteristics and the piston-bowl shape which were calibrated using CFD simulations and in-cylinder analyses. The VTEC mechanism is employed to control the burn rate with in-cylinder swirl gas motion, which is generated by one-intake-valve deactivation. Optimization of the mixture preparation and combustion through calibrations of the piston bowl, the fuel spray characteristics of the high pressure injector and the in-cylinder gas motion enabled stable combustion with an ultra lean air-fuel ratio of 65. As a result, this engine has significantly improved fuel economy and emissions.