Inlet port for internal combustion engine.

摘要

@ An inlet port for an internal combustion engine has an inlet port opened on an end face of a cylinder chamber at an off-center position, and the inlet hole is provided with an inlet valve and connected to an inlet passage. The inlet passage comprises a swirl generating section and an introducing section, and width between the peripheral surface of the valve stem of the inlet valve and the wall surface of the swirl generating section is made larger at the outside part on the wall side of the cylinder chamber than at the inside part on the center side of the cylinder chamber. The introducing section is connected to the outside part of the swirl generating section. In the plane intersecting perpendicularly to the center line of the introducing section within the parallel plane to the opening face of the inlet hole, the width of the outside part of the swirl generating section is set between 1.1 times and 2.8 times of the width of the inside part. The height from the opening face of the inlet hole to a ceiling of the swirl generating section is made to decrease from the outside part to the inlet part around the valve stem, and rate of reduction is set between 0% and 0.18% of the inlet hole diameter per one degree around the valve stem.