Soft Spray Formation of a Low-Pressure High-Turbulence Fuel Injector for Direct Injection Gasoline Engines 2002-01-2746

Currently, high-pressure fuel systems and swirl injectors dominate direct injection spark ignition (DISI) engine applications worldwide. Besides its advantage of good atomization due to the high pressure, this technology also has many inherent drawbacks, such as, high system cost, complicated system configuration, excessive wall wetting, lack of spray tailoring flexibility, etc., which limit the benefits available from the DISI concept. To overcome these drawbacks, a low-pressure direct injection (LPDI) fuel injector was developed which utilizes a novel high-turbulence nozzle to produce a soft spray, with droplet size comparable to the high-pressure swirl injector sprays, but much reduced penetration. This unique nozzle design provides a degree of independent control of injector flow, spray droplet size, spray angle, penetration, and spray distribution pattern. The injector operates at normal battery voltage and at a much lower system pressure which can be generated by an in-tank fuel pump. Therefore, the system complexity is significantly less than that of the high-pressure systems. This paper reports initial results of the prototype LPDI injector flow test and spray characterization, as well as engine dynamometer verification testing.