| 摘要 |
PROBLEM TO BE SOLVED: To promote the efficient formation of a whirl stream in particular by improving the distribution performance of EGR gas into each cylinder of an internal combustion engine, and preventing backflow of gas to a throttle valve. SOLUTION: This exhaust gas recirculation system is provided with an inlet system installed with a throttle valve 27 at the upstream side of an inlet pipe 23 equipped with four branch pipes 25 connecting to each cylinder and a collector 24, and introduces EGR gas from an exhaust system via an exhaust gas recirculation passage 31 into this inlet pipe 23 at the downstream side of the throttle valve 27 and at the upstream side of the collector 24. The EGR gas is introduced into a semi-annular EGR passage 32 set up in the circumferential direction of the inlet pipe 23 via the EGR passage 31, and then the EGR passage 32 and the inlet pipe 23 are interconnected to each other through a slitlike opening part 33. With this, a whirling movement is imparted to the EGR gas to be introduced from this slitlike opening part 33, whereby its mixture with fresh air is accelerated.
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