In-cylinder direct-injection spark-ignition engine

Abstract

An in-cylinder direct-injection spark-ignition engine using at least a homogeneous combustion mode and a stratified combustion mode and equipped with a pentroof combustion chamber head having first and second shallow-angled surfaces, comprises intake valves disposed in the first shallow-angled surface, exhaust valves disposed in the second shallow-angled surface. A pair of substantially straight intake ports are formed in the cylinder head. A tumble-and-swirl control valve is disposed in a first intake port of the substantially straight intake ports for adjusting the amount of intake air passing through the first intake port. A piston crown comprises an intake-valve side inclined surface generally parallel to the first shallow-angled surface, an exhaust-valve side inclined surface generally parallel to the second shallow-angled surface, and a piston bowl having an opening of a substantially complete round and arranged in an eccentric position with respect to the outside circle of the upper portion of the piston toward the intake valves. The piston bowl has a deeply-recessed bowl cavity. The deeply-recessed bowl cavity is arranged eccentrically to the opening of the piston bowl toward a second intake port of the substantially straight intake ports.