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Influence of Injection Timing on In-Cylinder Fuel Distribution in a Lean-Burn Engine
Published July 18, 1995 by Society of Automotive Engineers of Japan in Japan
Measurements are presented of droplet characteristics and air velocity in the cylinder of a 0.36 liter four valve engine, equipped with an sohc VTEC-E valve train and port injection. The results show that injection at crank angles, ϑinj(s), when the inlet valve is open results in the most of the liquid volume flux being in the form of droplets with Sauter mean diameter between 20 and 30 μm which strikes the sleeve up to about 2.5 cm below the exhaust valves, thus generating a locally rich cloud there. The amount of liquid phase gasoline passing through the plane 16 mm below the spark plug gap increases with ϑinj(s) up to 50 CA after intake TDC and this, together with the crank angle of droplet arrival and vapor generation, controls stratification of the gaseous fuel phase. The optimum injection time is when the fuel-rich cloud is generated so that the tumble vortex conve the spark plug at the time of ignition.