Combustion chamber for direct-injected spark-ignited engines with swirl airflows

摘要

A stratified-charge combustion chamber system for a direct-injection spark-ignited (DISI) engine with a swirl-type airflow. An asymmetrical combustion bowl design in the top wall of the piston provides a wide area on the downstream side of the swirl flow and a harbor area upstream of the swirl flow in a direction further away from the fuel injector. The edge of the combustion bowl is comprised of smoothly-connected curves with large radii, except for the curve connecting the wide and harbor areas, which has a small radius. The vertical cross-sections of the bowl also have large radii in order to guide the air-fuel mixture and rebounded fuel droplets toward the spark plug and prevent dead regions for the fuel. The precise position of the spark plug in the harbor area can be adjusted as desired within a certain range to improve ignitability of the air-fuel mixture.