Intake port structure in internal combustion engine

摘要

A powerful swirl in intake air flowing into a combustion chamber in an internal combustion engine is generated to enhance combustion efficiency. An intake port portion has an axis which is eccentric with respect to an axis of a cylinder bore and inclined with respect to a plane perpendicular to the axis of the cylinder bore. The intake port portion is partitioned off from an adjacent port portion through a partition wall. A deflecting recess is formed in a lower surface of the intake port portion to extend from a point of an upstream end of the partition wall to a point in the vicinity of an intake opening. When an intake valve is opened during a low-load operation of the internal combustion engine, intake air flowing through the intake port portion is deflected by the deflecting recess to flow into the combustion chamber substantially in parallel to a top face of a piston. Thus, the intake air flowing into the combustion chamber cannot be reduced in a speed component in a tangential direction of the cylinder bore, and a powerful swirl can be generated.