Effects of Fuel Atomization on Cold Starting of a 4 Stroke Cycle Spark Ignition Engine

Abstract

Effects of fuel atomization on cold starting of a 4 stroke cycle spark ignition engine were investigated experimentally. Two kinds of ultrasonic fuel injectors using a micro nozzle array (MNA injectors) were applied, whose nozzle diameter d=4 and 6 μm, respectively. A conventional port fuel injector (PFI injector) was also used for comparison. The Sauter mean diameters (SMDs) of the sprays were 15 μm (MNA, d = 4 μm), 23μm (MNA, d = 6 μm), and 59 μm (PFI), respectively, An air cooled, single cylinder, 4 stroke cycle, spark ignition engine was used. The first ignition cycles and the cumulative fuel amount were investigated at a wide range of the air fuel ratio. For the MNA injector (d = 4μm), the first ignition cycle became much earlier when compared with the PFI injector. The cumulative fuel amount during cold starting reduced by about 30%. It is shown that, by use of the MNA injector, the unburned hydrocarbon emissions during cold starting could be reduced.