The application of Controlled Auto-Ignition Gasoline Engines -The challenges and solutions
To be published on April 2, 2019 by SAE International in United States
Controlled auto-ignition (CAI) combustion, also known as homogeneous charge compression ignition (HCCI), has the potential to simultaneously reduce the fuel consumption and nitrogen oxides (NOx) emissions of gasoline engines. However, narrow operating region in loads and speeds is one of the challenges for the commercial application of CAI combustion to gasoline engines. Therefore, the extension of loads and speeds is an important prerequisite for the application of CAI combustion to gasoline engines. The effect of intake charge boosting, charge stratification and spark-assisted ignition on the operating range in CAI mode was reviewed. Stratified flame ignition (SFI) hybrid combustion is one form to achieve CAI combustion under the conditions of highly diluted mixture caused by the flame in the stratified mixture with the help of spark plug. CAI combustion in two-stroke gasoline engine can be used to enhance the torque of a four-stroke gasoline engine with the same displacement at the same indicated mean effective pressure. Poppet-valved two-stroke gasoline engines with normal valve lift and variable valve timing (VVT) device are promising to achieve CAI combustion in a wide operating range. Hence, CAI combustion in two-stroke gasoline engines is a feasible solution for its commercial application to vehicles.