| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sensor which can restrain water from creeping into a protective cover by a method wherein protrusions which protrude toward the outside of the protective cover are formed in the edge part of a through hole at least on one layer of the protective cover. SOLUTION: An oxygen sensor 1 is provided with a protective cover 3 which covers a detection part 2. The protective cover 3 is provided with a cylindrical inner cover 4 and with a cylindrical outer cover 5. A gap 7 is formed between the inner cover 4 and the outer cover 5. Inner through holes 41 and outer through holes 51 are formed nearly in the whole regions in the circumferential wall of the inner cover 4 and in the circumferential wall of the outer cover 5 in such a way that they are dispersed alternately at prescribed intervals. In addition, first protrusions 53 and second protrusions 43 are formed respectively at the outer through holes 51 and the inner through holes 41. Then, the first protrusions 53 act as barriers to water which creeps into the outer cover 5, and the water is hard to creep into the outer cover 5 from the outer through holes 51. Consequently, it is possible to restrain the water from creeping into the gap 7 between the the inner cover 4 and the outer cover 5. Even when the water creeps into the gap 7, the second protrusions 43 act as barriers to the water which creeps into the inner cover 4, and the life of the detection part 2 can be made long. |
