Examination of Factors Impacting Unaccounted Fuel Post GDI Fuel Injector Closing

The characteristics of gasoline sprayed directly into combustion chambers are of critical importance to engine out emissions and combustion system development. The optimization of the spray characteristics to match the in-cylinder flow field, chamber geometry, and spark location is a vital tasks during the development of an engine combustion strategy. Furthermore, the presence of liquid fuel during combustion in Spark-Ignition (SI) engines causes increased hydro-carbon (HC) emissions. Euro 6, LEVIII, and US Tier 3 emissions regulations reduce the allowable particulate mass significantly from the previous standards. LEVIII standards reduce the acceptable particulate emission to 1 mg/mile. A good DISI strategy vaporizes the correct amount of fuel just in time for optimal power output with minimal emissions. The opening and closing phases of DISI injectors are crucial to this task as the spray produces larger droplets during both theses phases. This paper illustrates the preliminary results looking at how deposits on the injector tip, fuel type, and manufacturer affect the fuel characteristics during injector closing. The data was collected using a novel technique developed at Ford’s Powertrain and Fuel Subsystems Lab. The review will focus on the variation of droplet diameter and the mass post injector closing for a given injector.