INTAKE PORT STRUCTURE OF INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide an intake port structure of an internal combustion engine capable of making both compatible a high swirl ratio and a flow rate factor. SOLUTION: This intake port structure of an engine E is composed of primary and secondary intake ports 2 and 3 in each of which an upstream end opens on an intake manifold connecting surface 11 and a downstream end opens in a combustion chamber 22 formed on the upper end of a cylinder 1. The primary intake port 2 is formed as a tangential port substantially contacting with its axis 2A to a virtual circle C passing through the center 2bA of a combustion chamber side opening 2b with the axis 1A of the cylinder 1 as a center. The secondary intake port 3 is formed a helical port for controlling its intake flow rate by an intake control valve and forming the vicinity of a combustion chamber side opening 3b in a spiral shape. Straight lines 2L and 3L of connecting the centers 2bA and 3bA of the combustion chamber side openings 2b and 3b to the centers 3aA and 3aA of intake manifold side openings 2a and 3a in both intake ports 2 and 3 are inclined by 45° or larger with respect to an upper en surface 1a of the cylinder 1. COPYRIGHT: (C)2009,JPO&INPIT