Combustion/NVH Analysis for Development of a 2-Valve Double Spark Plug Engine

An experimental activity aimed to analyze the noise emission of a small gasoline engine equipped with two spark plugs per cylinder was performed. A custom electronic device permitted to set the delay time between the first and second spark ignition with three different modalities: single spark, synchronous double spark and sequential double spark. Engine noise emission was analyzed at full load and at part load engine condition. The measurements were carried out in a semi-anechoic engine test cell. An acoustic binaural head system also permitted a subjective evaluation of the noise emission. Indicated measurements were also performed and correlated to the noise emission levels. With appropriate sequential double spark advances chosen, the experimental results put on evidence the satisfying noise emission of the sequential double spark versus synchronous double spark.