| 摘要 |
PROBLEM TO BE SOLVED: To prevent clogging of an exhaust-gas flowing port with the soot in exhaust gas in an oxygen-concentration detector, wherein an oxygen- concentration detecting part coated with a cover body in which the exhaust-gas flowing port is formed is protruding into the exhaust pipe in an internal combustion engine and operated at high temperature. SOLUTION: A cover body 5A is constituted of first, second and third cover bodies 51, 52 and 53 in three layers at the inside and outside. A third exhaust- gas flowing port 531 of the third cover body 53 is formed in a trumpet shape at a position facing a second exhaust-gas flowing port 521 of the second cover body 52. At the same time, the diameter of the opening end of the port 531 is made larger than that of the second exhaust-gas flowing port 521 so as to suppress the clogging by soot. The above described opening end is made to approach around the second exhaust-gas flowing port 521 so than the part between the second cover body 52 and the third cover body 53 is substantially closed. Thus, the heat deprivation by the exhaust gas in the second cover body 52 is suppressed, and the clogging with the soot of the second exhaust-gas flowing port 521 is suppressed. |
