| 摘要 |
PROBLEM TO BE SOLVED: To achieve both responsiveness and durability at high levels by preventing degradation of a sensor caused by the clinging of dirt to a gas concentration detecting part, and making sufficiently large the amount of flow of gas to be measured which passes over the surface of the gas concentration detecting part. SOLUTION: A sensor element 2 whose end having a gas concentration detecting part 21 projects into an exhaust pipe is passed and held inside a housing 1 secured to the exhaust pipe wall of an internal combustion engine, and a portion around the end of the sensor element 2 is covered with a protective cover 3. The protective cover 3 is formed into a double structure consisting of inside and outside covers 32, 31, and gas circulating holes 31a, 32a pointed to the flow of gas to be measured are provided oppositely to each other in the circumferential walls of the inside and outside covers 32, 31 above the gas concentration detecting part 21 of the sensor element 2. Gas circulating holes 32b, 32c in the inside cover are provided in the lower circumferential walls in such a way as to be located between gas circulating holes 31e to 31h in the outside cover. |
