INTAKE SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an intake system of an internal combustion engine that sucks an EGR lean gas where an EGR gas concentration is lean and an EGR rich gas where the EGR gas concentration is rich so that they form stratified distribution and that can improve a degree of stratification of the EGR lean gas and the EGR rich gas.SOLUTION: A passage 22 in which an EGR lean gas flows is connected to a swirl generation port 12 of an engine 10, and a passage 25 in which an EGR rich gas flows is connected to a tumble generation port 13 of the engine 10. A connection passage 29 is provided which connects the passage 22 with the passage 25. An ECU 50 delays valve opening of an intake valve 142 of the tumble generation port 13 further than valve opening of an intake valve 141 of the swirl generation port 12, and thereby causes the EGR rich gas to be sucked in the middle of an intake stroke. Furthermore, the ECU 50 changes a lift amount or a period of starting valve opening in the intake valve 142 so that an amount of the EGR rich gas sucked from the tumble generation port 13 increases more when a target EGR rate is high than when that is low.