INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide an internal combustion engine in which tumble in a combustion chamber 2 is improved by the inside of an intake port 3 with a high degree of freedom in design. SOLUTION: In the internal combustion engine 1 having the intake port 3 formed to a cylinder head so that one end thereof is opened to the combustion chamber 2 of a lower surface of the cylinder head, a stepped surface 5 projected toward the inside of the intake port 3 and changing an intake flow in the intake port 3 is formed to an inner wall face of the intake port 3 at a position neighboring the combustion chamber 2 so as to be continuous along a longitudinal direction of the intake port 3. Therefore, a draft angle in demolding is easily disposed to an intake port core defining a shape of the intake port 3, so that the degree of freedom in design of the intake port 3 is enhanced. By the intake port 3 with high degree of freedom in design, the tumble in the combustion chamber 2 is improved. COPYRIGHT: (C)2008,JPO&INPIT