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This paper describes a cold start emission reduction system developed for a 3.0L V6 test vehicle in order to meet SULEV emission regulations. The emphasis of this research is how the system can be used to meet SULEV emission standards without the need for a heavily loaded catalyst. A fuel-vaporizing device has been developed that generates vaporized fuel to be consumed during engine start up. The device allows for lean A/F ratio control during engine start and idle and is called a Combustion Stabilizing Device (CSD). A vehicle with a CSD mounted to the engine was tested in an emission lab. The test vehicle resulted in approximately 50% HC emission reduction in the first 20s of engine startup and had a catalyst warm-up time to T50 (50% converter efficiency) of less than 20s.

We propose a flat spray pattern to improve conventional stratified-charge combustion systems in a direct-injection (DI) gasoline engine. Swirl-type DI fuel injectors with a V-groove cut orifice nozzle (V-groove nozzle) and a rectangular-groove cut orifice nozzle (U-groove nozzle) are newly designed. We examine experimentally the characteristics of newly designed injector nozzles under various ambient pressure and fuel pressure conditions. The fuel spray characteristics were tested inside an experimental pressure chamber. The resulting spray patterns were illuminated by YAG-laser sheet and recorded by CCD cameras. The atomization of fuel-spray in the V-groove and U-groove nozzle was also investigated. These experiments showed that the V-groove and the U-groove nozzles generate a well-atomized flat fuel-spray pattern that can be controlled by the orifice-depth and it is robust under ambient pressure variations.