Experimental studies have been carried out on homogeneous charge, spark ignition engines running on European pump-grade, 95 RON gasoline. The aim was to determine the limits on dilution and mixture proportions imposed by a deterioration in engine cycle-by-cycle combustion stability. The stable limit was taken as corresponding to a COVimep of 10%. Residual gas fraction was raised through engine load and valve timing changes, and determined by cylinder gas sampling. The results define a bounded region of stable operation on two diagrams, with axes of air/burned gas and fuel/burned gas for the first and burned gas fraction and air/fuel ratio for the second. For stable operation, gas/fuel ratio is limited to around 25:1 and is the constraint on upper limits of dilution and air/fuel ratio. For fuel-rich mixture operation, the limiting value of air/fuel ratio rises from around 9:1 to stoichiometric as burned gas fraction increases. The limiting value of burned gas fraction was less than or around 0.3.
Limits on Charge Dilution, Fuel and Air Proportions for Stable Combustion in Spark Ignition Engines
Sae Technical Papers
SAE 2004 World Congress & Exhibition ; 2004
2004-03-08
Aufsatz (Konferenz)
Englisch
Limits on Charge Dilution, Fuel and Air Proportions for Stable Combustion in Spark Ignition Engines
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