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A fuel injector adapter which can divide the fuel spray into two streams and produce fine fuel atomization is being developed to improve fuel economy and transient performance in four-valve gasoline engines. The adapter has the shape of a pair of spectacles and is attached to the orifice outlet of the injector. The optimum shape of the adaptor is investigated by 3-D viscous flow analysis by FEM and experiment. A 17% improvement in transient performance over the conventional Hitachi injector is confirmed by engine tests in a passenger car.

The effect of fuel injection fuel atomization on engine performance has been studied in order to improve fuel economy and emission characteristrics. The fuel swirl method for injector atomization was studied both by fuel flow analysis and prototype experimentation. The goal of the studies was to develop fine fuel atomization over a wide engine operation range. As a result of our studies, it has been concluded that a desirable atomization can be obtained when the fuel is swirled in a circumferential direction and the swirl number is greater than 0.6. Protoype injectors applying these principles have been developed and tested in passenger car engines. The test results show that 3% improvement in fuel consumption and 8% reduction in hydro-carbon emission can be expected when fine atomization injectors are installed.