Controlled auto-ignition

Controlled Auto-Ignition (CAI) feature in vehicle engines allows significant fuel efficiency and low NOx emission levels, as compared to conventional spark-ignited combustion concepts. A homogeneous gaseous mixture is compressed in gasoline auto-ignition that ignites automatically, when a sufficiently high temperature and pressure are reached within the combustion chamber. The mixture starts to react simultaneously in several locations, after the ignition temperature has been reached during compression. CAI-based ignition also faces several challenges, including inability of its operating mode to be extended to high loads, due to required dilution and adherence to an acceptable combustion noise level. The ignition time of CAI is also controlled by the reaction kinetics and determined by the thermal condition of the gas at the 'intake closing' event. It is suggested that significant benefits from CAI, can be achieved by considering complex overall system of a vehicle.