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A direct-injection spark-ignition engine operable between a stratified charge combustion mode where fuel injection is executed on a compression stroke while introducing a vertical-vortex tumble flow to an induced air drawn into a combustion chamber through an intake port, and a homogeneous combustio

A direct-injection spark-ignition engine operable between a stratified charge combustion mode where fuel injection is executed on a compression stroke while introducing a vertical-vortex tumble flow to an induced air drawn into a combustion chamber through an intake port, and a homogeneous combustion mode where fuel-injection early in the intake stroke produces a homogeneous air-fuel mixture, comprises a cylinder block having a cylinder, a piston movable through a stroke in the cylinder and having a centrally-formed piston bowl cavity combustion chamber in its piston head, a cylinder head mounted on the cylinder block, a centrally-located spark plug, and a fuel injector valve provided nearby the intake valve for injecting fuel directly into the combustion chamber. The piston bowl cavity combustion chamber is formed, so that the deepest portion of the piston bowl cavity combustion chamber is obtained at the center of the piston head, and the inner peripheral concave wall surface of the cavity combustion chamber is contoured to be curved in a direction of a streamline of the vertical-vortex tumble flow.

대표청구항 ▼

[ What is claimed is:] [1.] A direct-injection spark-ignition engine operable in at least a stratified charge combustion mode where fuel injection is executed on a compression stroke while introducing a vertical-vortex tumble flow to an induced air drawn into a combustion chamber through an intake p

[ What is claimed is:] [1.] A direct-injection spark-ignition engine operable in at least a stratified charge combustion mode where fuel injection is executed on a compression stroke while introducing a vertical-vortex tumble flow to an induced air drawn into a combustion chamber through an intake port, comprising:a cylinder block having a cylinder;a piston movable through a stroke in the cylinder, and having a piston bowl cavity combustion chamber in a piston head;a cylinder head mounted on said cylinder block;a spark plug centrally located at a center of the combustion chamber; anda fuel injector valve provided at a side wall portion of the combustion chamber and near an intake valve disposed in the intake port, for injecting fuel directly into the combustion chamber;said piston bowl cavity combustion chamber being formed in the piston head, so that a deepest portion of said piston bowl cavity combustion chamber is obtained at a center of the piston head, and an inner peripheral concave wall surface of said piston bowl cavity combustion chamber is contoured to be curved in a direction of a streamline of the vertical-vortex tumble flow.