| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust passage structure for an internal combustion engine, which smoothly controls an internal combustion engine, based on information from an oxygen concentration sensor, and prevents deterioration in detection accuracy or failure of the oxygen concentration sensor caused by deposition of condensate water. SOLUTION: The oxygen concentration sensor 4 is interposed between catalysts 21, 22 of a tandem type exhaust cleaning catalyst disposed in the middle of an exhaust passage 1, and a sensor element part 41 is positioned above the center Q of an approximately center part in an exhaust flow direction of the casing 30. An approximately cylindrical guide 31 for guiding an exhaust flow to the sensor element part 41 is disposed immediately downstream of an upstream catalyst 21, a bore diameter of a downstream end opening 312a of the guide 31 is formed to be a diameter smaller than a diameter of an upstream end opening 311a. The center P of the downstream end opening 312a of the guide 31 is deviated to be closer to the sensor element part 41 than the center Q of the casing 30, and a plurality of exhaust ports 33, 33 are formed in a lower position of the guide 31. The exhaust ports 33, 33 discharge the condensate water in the exhaust condensed in contact with the guide 31, on the upstream from the downstream end opening 312a to the outside of the guide 31. COPYRIGHT: (C)2009,JPO&INPIT
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