Ngk Spark Plug Company, Limited

Other

Honda Motor Co., Ltd.

Teppei Okawa

Seiichi Hosogai

Akio Mizutani

Hiroshi Kubota

Hiroyuki Fujita

Akio Takami

Toshitaka Matsuura

Hiroshi Isomura

Takashi Nakao

Keizo Furusaki

Mineji Nasu

Shinya Awano

Mitsunori Oi

Keisuke Makino

A gas sensor including a detection element having a front-end portion, a detection portion formed at the front-end portion of the detection element, and a protector that covers the detection portion. The protector includes a first portion having a first sidewall and a second portion having a second sidewall disposed outside the first portion. The first sidewall has an axial front end and a tapering portion. The tapering portion is formed from the axial front end of the first sidewall. The side portion has a front-end surface provided with a first gas outlet, and the second portion has a front-end surface provided with a second gas outlet. Furthermore, at least one gas inlet is formed to the sidewall of the second portion opposite the tapering portion, and plural gas inlets are formed on the sidewall of the first portion.

Gas sensor

There is disclosed an oxygen sensor disposed before an exhaust gas purifying catalyst of an engine which uses a hydrocarbon containing fuel with a H/C ratio of three or more. An oxygen sensor,is provided with a solid electrolytic body,which can generate a difference in oxygen concentration with reference gas and measured gas, a reference electrode,and a detection electrode,formed on inner and outer surfaces of the solid electrolytic body,, and a porous protective layer,for covering the detection electrode,. The detection electrode,is formed only of a metal like Pt which promotes oxidizing reaction of methane to have a thickness of 1 to 2 &mgr;m. In the protective layer,, only a second protective layer,carries Pt catalyst,which promotes oxidizing reaction of hydrogen, and the amount of carried catalyst is in the range of 0.5 to 7 mol % relative to the whole of the second protective layer,. According to the oxygen sensor,, even if a large amount of hydrogen is exhausted, for example, from CNG engine, or even if a large amount of methane is exhausted, an excellent engine control can be realized.

Oxygen sensor

An oxygen sensor is disposed behind an exhaust gas purifying catalyst for an internal combustion engine and which suppresses the influence of unburnt hydrocarbon on the output voltage. A sensor element,is provided with a detection electrode,on the outer face of a zirconia ceramic body,, a reference electrode,on the inner face of the ceramic body,and a spinel protective layer,on the outer surface of the detection electrode,. The tip end of the sensor element,is covered with a protective cover,which is provided with an outer partition wall,having through holes,and an inner partition wall,having through holes,. In a case where the pressure difference between the inside and outside of the protective cover,is &Dgr;P(atm) when the atmospheric air with a volume flow rate Q(L/min) is passed into the protective cover,from the outside, the ratio &Dgr;P/Q,is 3.2&times;10,(atm&middot;min,&middot;L,). When the surface temperature of the sensor element,is changed in a range of sensor active temperature, the reversing time is substantially constant. Therefore, the catalyst deterioration can be detected by the oxygen sensor with high accuracy.

A laminar gas-sensitive thick film consisting of ceramic semiconductor and metallic catalyzer is formed across a pair of electrodes carried by a ceramic substrate, and the nature of metallic catalyzer on an outer surface layer of the thick film is different from that of metallic catalyzer in that portion of the thick film which is in the proximity of the electrodes.

Thick-film gas-sensitive element

Growing community of inventors

Kounan, Japan

Teppei Okawa