| 摘要 |
First inner gas holes 134a and first outer gas holes 144a of a gas sensor are formed so that the following conditions are satisfied: a first-inner-hole count Nin≧3, 0<an inner/outer hole count ratio Nr≦0.5, and 0<an inner/outer hole-area ratio Ar≦0.25, where the first-inner-hole count Nin represents the number of first inner gas holes 134a, a first-inner-hole average area Ain [mm2] represents (the total opening area of the first inner gas holes 134a)/(the first-inner-hole count Nin), a first-outer-hole count Nout represents the number of the first outer gas holes 144a, a first-outer-hole average area Aout represents (the total opening area of the first outer gas holes 144a)/(the first-outer-hole count Nout), the inner/outer hole count ratio Nr represents the first-inner-hole count Nin/the first-outer-hole count Nout, and the inner/outer hole-area ratio Ar represents the first-inner-hole average area Ain/the first-outer-hole average area Aout. |
| 主权项 |
1. A gas sensor including:
a sensor element capable of detecting the concentration of predetermined gas in measured gas, an inner protection cover having a bottomed cylindrical shape and covering a tip end of the sensor element, where the inner protection cover has at least three first inner gas holes and at least one second inner gas hole formed at a position further away in a tip direction of the sensor element than the first inner gas holes, an outer protection cover having a bottomed cylindrical shape and covering the inner protection cover, where the outer protection cover includes a cylindrical body portion having a plurality of first outer gas holes formed therein and a bottomed cylindrical tip end portion having at least one second outer gas hole formed therein and having an inner diameter that is smaller than an inner diameter of the body portion, a first gas chamber formed as a space between the body portion of the outer protection cover and the inner protection cover, where the first gas chamber communicates with the inside of the inner protection cover through the first inner gas holes, and; a second gas chamber formed as a space between the tip end portion of the outer protection cover and the inner protection cover, where the second gas chamber does not directly communicate with the first gas chamber and communicates with the inside of the inner protection cover through the second inner gas hole, wherein the first inner gas holes and the first outer gas holes are formed so that the following conditions are satisfied: 0<an inner/outer hole count ratio Nr≦0.5 and 0<an inner/outer hole-area ratio Ar≦0.25 (where the first-inner-hole count Nin represents the number of first inner gas holes, a first-inner-hole average area Ain [mm2] represents (the total opening area of the first inner gas holes)/(the first-inner-hole count Nin), a first-outer-hole count Nout represents the number of the first outer gas holes, a first-outer-hole average area Aout [mm2] represents (the total opening area of the first outer gas holes)/(the first-outer-hole count Nout), the inner/outer hole count ratio Nr represents the first-inner-hole count Nin/the first-outer-hole count Nout, and the inner/outer hole-area ratio Ar represents the first-inner-hole average area Ain/the first-outer-hole average area Aout). |
