INTAKE PORT SHAPE OF INTERNAL COMBUSTION ENGINE

摘要

An intake port shape of internal combustion engine which suppresses a part of intake flow which is likely to flow in a reverse swirl direction on collision with a valve stem and produces a strong swirl while suppressing a flow coefficient from being deteriorated, wherein a valve seat supporting annular stepped surface (14) is formed at the outlet part of an intake port of a cylinder head (1), its inner peripheral edge shape uses the shape of an inner peripheral edge (4a) of a valve seat (4) as a reference circumference, an extension part (15) projecting toward a valve stem (11) side is provided at the inlet part of the intake part of the intake port in the radial direction, the extension part (15) is formed in an angle-, arc-, or trapezoidal-shape which expands from a top part (15a), the most projected part toward a valve stem side, to both sides in circumferential direction and of which base end is connected to the reference circumference, and a rear wall (16) which is gradually lower in projected height toward the upstream side of the intake port and connected smoothly to the inner peripheral wall surface of the intake port (2) is formed on the side opposite to the valve seat side of the extension part (15).