JPH10221298A - Nitrogen oxide concentration detector - Google Patents
Nitrogen oxide concentration detectorInfo
- Publication number
- JPH10221298A JPH10221298A JP9159195A JP15919597A JPH10221298A JP H10221298 A JPH10221298 A JP H10221298A JP 9159195 A JP9159195 A JP 9159195A JP 15919597 A JP15919597 A JP 15919597A JP H10221298 A JPH10221298 A JP H10221298A
- Authority
- JP
- Japan
- Prior art keywords
- oxygen
- nitrogen oxide
- concentration
- gap
- oxide concentration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、たとえば燃焼器や
内燃機関の排ガスの成分である窒素酸化物濃度を検出す
るために使用される窒素酸化物濃度検出器及び窒素酸化
物濃度検出方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrogen oxide concentration detector and a nitrogen oxide concentration detection method used for detecting, for example, the concentration of nitrogen oxide which is a component of exhaust gas from a combustor or an internal combustion engine.
【０００２】[0002]
【従来の技術】従来の窒素酸化物濃度検出器としては、
例えばＳＡＥ ｐａｐｅｒ Ｎｏ．９６０３３４ ｐ１
３７〜１４２ １９９６に、薄板状ジルコニアからなる
固体電解質層の積層体の内部に、第１酸素ポンピングセ
ルと酸素濃度測定セルを有する第１空隙部と、第２酸素
ポンピングセルを有する第２空隙部と、第１空隙部を被
測定ガス側と連通する第１拡散通路と、第１空隙部と第
２空隙部との間を連通する第２拡散通路とを備えた図３
の平面図と図４のＡ−Ａ’拡大断面図に示す窒素酸化物
濃度検出器が開示されている。2. Description of the Related Art Conventional nitrogen oxide concentration detectors include:
For example, SAE paper No. 960334 p1
37-142, 1996, a first void portion having a first oxygen pumping cell and an oxygen concentration measuring cell and a second void portion having a second oxygen pumping cell inside a laminated body of a solid electrolyte layer made of sheet zirconia. FIG. 3 having a first diffusion passage communicating the first gap with the measured gas side, and a second diffusion passage communicating between the first gap and the second gap.
And a nitrogen oxide concentration detector shown in an enlarged sectional view taken along the line AA ′ of FIG. 4 are disclosed.
【０００３】図４において、１は第１拡散通路、２は第
１空隙部、３は第２拡散通路、４は第２空隙部、５-
１、５−２、５−３、５−４、５−５及び５−６は積層
された薄板状ジルコニアの固体電解質層、６は第１酸素
ポンピングセル、７は酸素濃度測定セル、８は第２酸素
ポンピングセル、９は大気導入部、１０は加熱ヒータで
ある。第１酸素ポンピングセル６、酸素濃度測定セル７
及び第２酸素ポンピングセル８には、多孔質白金又は多
孔質ロジウムからなる電極６−ａ、６−ｂ、７−ａ、７
−ｂ、８−ａ及び８−ｂがそれぞれ設けられている。以
下、本明細書では、酸素ポンピングセルや酸素濃度測定
セルを酸素セルと呼ぶことにする。In FIG. 4, reference numeral 1 denotes a first diffusion passage, 2 denotes a first gap, 3 denotes a second diffusion passage, and 4 denotes a second gap.
1, 5-2, 5-3, 5-4, 5-5 and 5-6 are laminated solid electrolyte layers of thin zirconia, 6 is a first oxygen pumping cell, 7 is an oxygen concentration measuring cell, and 8 is A second oxygen pumping cell, 9 is an atmosphere introduction unit, and 10 is a heater. First oxygen pumping cell 6, oxygen concentration measuring cell 7
And the second oxygen pumping cell 8 has electrodes 6-a, 6-b, 7-a, 7 made of porous platinum or porous rhodium.
-B, 8-a and 8-b are provided respectively. Hereinafter, in this specification, the oxygen pumping cell and the oxygen concentration measuring cell are referred to as oxygen cells.
【０００４】この窒素酸化物濃度検出器では、加熱ヒー
タ１０に通電することによって各酸素セルの温度が一定
値に保持される。内燃機関の排ガスなどの被測定ガス
は、第１拡散通路１を通って第１空隙部２に導入され、
第１空隙部２に導入された被測定ガスから、第１酸素ポ
ンピングセル６によって酸素が抜き取られる。第１空隙
部２内の酸素濃度は、酸素濃度測定セル７によって監視
され、窒素酸化物が分解しない低い酸素濃度にまで酸素
が抜き取られ、この酸素濃度に保持される。In this nitrogen oxide concentration detector, the temperature of each oxygen cell is maintained at a constant value by energizing the heater 10. A gas to be measured such as exhaust gas from an internal combustion engine is introduced into the first gap 2 through the first diffusion passage 1,
Oxygen is extracted from the gas to be measured introduced into the first gap 2 by the first oxygen pumping cell 6. The oxygen concentration in the first gap 2 is monitored by the oxygen concentration measuring cell 7, oxygen is extracted to a low oxygen concentration at which nitrogen oxides are not decomposed, and is maintained at this oxygen concentration.
【０００５】この、低酸素濃度に保持された第１空隙部
２内のガスが、第２拡散通路３を通って第２空隙部４に
導入される。次いで第２空隙部４に導入された被測定ガ
スから、第２酸素ポンピングセル８によって酸素が抜き
取られる。この第２酸素ポンピングセル８で、酸素がほ
とんどすべて抜き取られてさらに低い酸素濃度になるた
め、また、電極として用いた多孔質ロジウムの触媒機能
によって窒素酸化物が完全に窒素と酸素に分解されるた
め、窒素酸化物の分解された酸素が第２酸素ポンピング
セル８によって抜き取られる。このとき、第２酸素ポン
ピングセル８に流れる電流値（μＡ）は、被測定ガス中
に含まれる窒素酸化物の濃度（ｐｐｍ）と直線関係を有
するので、あらかじめ窒素酸化物の濃度とポンプ電流Ｉ
ｐ2との相関関係を求めておけば、被測定ガス中に含ま
れる窒素酸化物濃度を検出することができる。The gas in the first gap 2 maintained at a low oxygen concentration is introduced into the second gap 4 through the second diffusion passage 3. Next, oxygen is extracted from the gas to be measured introduced into the second gap 4 by the second oxygen pumping cell 8. In this second oxygen pumping cell 8, almost all oxygen is extracted to lower the oxygen concentration, and nitrogen oxide is completely decomposed into nitrogen and oxygen by the catalytic function of porous rhodium used as an electrode. Therefore, the decomposed oxygen of the nitrogen oxide is extracted by the second oxygen pumping cell 8. At this time, since the current value (μA) flowing through the second oxygen pumping cell 8 has a linear relationship with the concentration (ppm) of nitrogen oxide contained in the gas to be measured, the concentration of nitrogen oxide and the pump current I
if seeking correlation between the p 2, it can be detected nitrogen oxide concentration in the measurement gas.
【０００６】[0006]
【発明が解決しようとする課題】この窒素酸化物濃度検
出器による窒素酸化物濃度の検出値は、ＣＯ、炭化水
素、ＣＯ2、ＳＯ2などの他のガス成分が共存していても
影響されない。しかし、被測定ガス中にある酸素によっ
てある程度影響される。その影響はあまり大きくない
が、低濃度の窒素酸化物を検出するときには大きな誤差
となる。また、窒素酸化物濃度検出器の使用時には、固
体電解質層が７００℃程度に加熱されるため、固体電解
質層の比抵抗が数百Ωｃｍ程度にまで低下する。このた
め、同一の固体電解質層上に酸素濃度測定セルと第２酸
素ポンピングセルの電極が設けられている従来の検出器
では、電極間に電流リークがあるために酸素濃度の測定
精度が悪く、第１空隙部内の酸素濃度を精度よく制御で
きないことによって窒素酸化物濃度の検出精度が劣ると
いう問題がある。また、ＥＰ０６７８７４０Ａ１に開示
されている窒素酸化物濃度検出器についても同様であ
る。The detected value of the nitrogen oxide concentration by this nitrogen oxide concentration detector is not affected even if other gas components such as CO, hydrocarbons, CO 2 and SO 2 coexist. . However, it is affected to some extent by oxygen in the gas to be measured. The effect is not so large, but a large error occurs when detecting a low concentration of nitrogen oxides. Further, when the nitrogen oxide concentration detector is used, the solid electrolyte layer is heated to about 700 ° C., so that the specific resistance of the solid electrolyte layer is reduced to about several hundred Ωcm. For this reason, in the conventional detector in which the electrodes of the oxygen concentration measurement cell and the second oxygen pumping cell are provided on the same solid electrolyte layer, the measurement accuracy of the oxygen concentration is poor due to the current leak between the electrodes, Since the oxygen concentration in the first gap cannot be controlled with high accuracy, there is a problem that the detection accuracy of the nitrogen oxide concentration is inferior. The same applies to the nitrogen oxide concentration detector disclosed in EP0678740A1.
【０００７】他方、特開昭６２−２７６４５３号には、
図５に示す構造の、複数の固体電解質層５−１、５−
２、５−３及び５−４と多孔質の電極６−ａ、６−ｂ、
７−ａ、７−ｂ、７−ｃ、８−ａ及び８−ｂからなる複
数の酸素セルを有する空燃比センサが開示されている。
この空燃比センサには、被測定ガスの導入部の第１拡散
通路１側にある第１空隙部２と、第１空隙部２と比べて
ガス拡散抵抗を第１拡散通路１の約２倍にした第２拡散
通路３で連通された第２空隙部４とがあり、第１空隙部
２と第２空隙部４の２箇所に酸素濃度測定セル７、７’
が設けられ、両酸素濃度測定セル７、７’を空燃比のリ
ーン域とリッチ域で使い分けることによってリーン域に
おける酸素濃度の検出精度を向上させている。また、被
測定ガスが内燃機関の排ガスである場合など、被測定ガ
ス中に含まれるパティキュレートによって第１拡散通路
１の通気性が悪くなっても、第２拡散通路３が目詰まり
しないことを利用して、検出値の経時変化を補正するよ
うにしているので、酸素濃度の検出値に基いて求める空
燃比を長期間にわたって精度よく検出できる空燃比セン
サとなっている。On the other hand, Japanese Patent Application Laid-Open No. 62-276453 discloses that
A plurality of solid electrolyte layers 5-1, 5-
2, 5-3 and 5-4 and porous electrodes 6-a, 6-b,
An air-fuel ratio sensor having a plurality of oxygen cells consisting of 7-a, 7-b, 7-c, 8-a and 8-b is disclosed.
This air-fuel ratio sensor has a first air gap 2 on the first diffusion path 1 side of the gas introduction section and a gas diffusion resistance that is about twice that of the first air diffusion path 1 as compared with the first air gap 2. There is a second void portion 4 communicated with the second diffusion passage 3, and oxygen concentration measurement cells 7 and 7 ′ are provided at two places of the first void portion 2 and the second void portion 4.
The oxygen concentration measurement cells 7, 7 'are used separately in a lean region and a rich region of the air-fuel ratio to improve the detection accuracy of the oxygen concentration in the lean region. Further, even when the gas to be measured is an exhaust gas of an internal combustion engine, the second diffusion passage 3 is not clogged even if the gas permeability of the first diffusion passage 1 is deteriorated by the particulates contained in the gas to be measured. The air-fuel ratio sensor is capable of accurately detecting the air-fuel ratio obtained based on the detected value of the oxygen concentration over a long period of time because the detection value is used to correct the temporal change of the detected value.
【０００８】本発明は、被測定ガス中の窒素酸化物濃度
を高精度で検出でき、小型で安価な窒素酸化物濃度検出
器の提供を目的とする。さらに本発明は、被測定ガス中
の窒素酸化物を実用レベルにおいて高精度で検出可能な
窒素酸化物濃度検出方法を提供することを目的とする。An object of the present invention is to provide a small and inexpensive nitrogen oxide concentration detector which can detect the concentration of nitrogen oxides in a gas to be measured with high accuracy. Still another object of the present invention is to provide a nitrogen oxide concentration detection method capable of detecting nitrogen oxides in a gas to be measured at a practical level with high accuracy.
【０００９】[0009]
【課題を解決するための手段】本発明の第１の視点にお
ける窒素酸化物濃度検出器は、固体電解質層に一対の多
孔質の電極を備えてなる第１酸素ポンピングセル及び酸
素濃度測定セルを有する第１空隙部と、固体電解質層に
一対の多孔質の電極を備えてなる第２酸素ポンピングセ
ルを有する第２空隙部と、第１空隙部を被測定ガス側に
連通する第１拡散通路と、第１空隙部を第２空隙部に連
通する第２拡散通路とを備える固体電解質層が積層され
てなる窒素酸化物濃度検出器であって、第１酸素ポンピ
ングセル、酸素濃度測定セル及び第２酸素ポンピングセ
ルがいずれも互いに異なる固体電解質層に設けられてい
ることを特徴とする。固体電解質層としては例えば薄板
状ジルコニアを用い、これを挟んで一対の多孔質電極を
設けることができる。According to a first aspect of the present invention, there is provided a nitrogen oxide concentration detector comprising a first oxygen pumping cell and an oxygen concentration measurement cell each having a pair of porous electrodes in a solid electrolyte layer. A first void portion, a second void portion having a second oxygen pumping cell having a pair of porous electrodes in the solid electrolyte layer, and a first diffusion passage communicating the first void portion to the gas to be measured. And a solid oxide layer having a second diffusion passage communicating the first gap with the second gap, the nitrogen oxide concentration detector comprising: a first oxygen pumping cell; an oxygen concentration measurement cell; Each of the second oxygen pumping cells is provided in a different solid electrolyte layer. For example, thin zirconia is used as the solid electrolyte layer, and a pair of porous electrodes can be provided with the zirconia sandwiched therebetween.
【００１０】[0010]
【発明の実施の形態】ジルコニアの固体電解質として
は、ジルコニアとイットリアの固溶体やジルコニアとカ
ルシアの固溶体が代表的なものであるが、他にハフニア
の固溶体、ペロブスカイト型酸化物固溶体、３価金属酸
化物固溶体等も使用できる。固体電解質の表面に設ける
多孔質の電極としては、触媒機能を有する白金やロジウ
ムあるいはその合金を使用するのが好ましい。その形成
方法は、たとえば白金粉末に固体電解質と同じ材料の粉
末を混合したものをペースト状とし、固体電解質層上に
スクリーン印刷し、次いで焼結する厚膜形成方法や溶射
による皮膜形成方法がある。電極が触媒機能を有してい
ると、窒素酸化物の検知を妨害する一酸化炭素や炭化水
素ガスが触媒作用によって分解され、除去される。ま
た、拡散通路には、細い貫通孔を有するセラミックスや
多孔質セラミックスを使用するのが好ましい。DESCRIPTION OF THE PREFERRED EMBODIMENTS As a solid electrolyte of zirconia, a solid solution of zirconia and yttria and a solid solution of zirconia and calcia are typical. A solid solution or the like can also be used. As the porous electrode provided on the surface of the solid electrolyte, it is preferable to use platinum, rhodium, or an alloy thereof having a catalytic function. As a forming method, for example, there is a method of forming a thick film by mixing a powder of the same material as a solid electrolyte with platinum powder to form a paste, screen printing on a solid electrolyte layer, and then sintering, or a method of forming a film by thermal spraying. . When the electrode has a catalytic function, carbon monoxide and hydrocarbon gas that interfere with the detection of nitrogen oxides are decomposed and removed by the catalytic action. In addition, it is preferable to use a ceramic having a small through hole or a porous ceramic for the diffusion passage.
【００１１】本発明の窒素酸化物濃度検出器は、薄板状
ジルコニアからなる固体電解質層の積層体の内部に、第
１酸素ポンピングセル及び酸素濃度測定セルを有する第
１空隙部と、第２酸素ポンピングセルを有する第２空隙
部と、第１空隙部を被測定ガス側と連通する第１拡散通
路と、第１空隙部を第２空隙部に連通する第２拡散通路
とを備えている点において前述のＳＡＥ ｐａｐｅｒ
Ｎｏ．９６０３３４に記載された窒素酸化物濃度検出器
と同じであるが、酸素濃度測定セルの電極と第２酸素ポ
ンピングセルの電極とが同じ固体電解質層上に設けられ
ていない点が異なっている。A nitrogen oxide concentration detector according to the present invention includes a first void portion having a first oxygen pumping cell and an oxygen concentration measurement cell inside a laminate of a solid electrolyte layer made of thin plate zirconia; A second gap having a pumping cell; a first diffusion passage communicating the first gap with the measured gas side; and a second diffusion passage communicating the first gap with the second gap. In the above SAE paper
No. It is the same as the nitrogen oxide concentration detector described in 960334, except that the electrode of the oxygen concentration measurement cell and the electrode of the second oxygen pumping cell are not provided on the same solid electrolyte layer.
【００１２】この相違によって本発明の窒素酸化物濃度
検出器では、酸素濃度測定セルと第２酸素ポンピングセ
ルの電極間に生じる電流リークが顕著に減少し、第１空
隙部内の酸素濃度の測定精度が向上して第１空隙部内の
酸素濃度を精度よく制御することができる。これによっ
て第１空隙部内の酸素濃度を、窒素酸化物が分解を始め
る酸素濃度に近い低レベルに安定して制御できるので、
微量である排ガス中の窒素酸化物濃度の検出精度が顕著
に向上する。本発明による上述の構造を有する窒素酸化
物濃度検出器は、セラミックス多層基板の製造技術をセ
ラミックス固体電解質材料に適用することによって、小
型の窒素酸化物濃度検出器を、生産性よく安価に製造で
き、かつ提供できる。[0012] Due to this difference, in the nitrogen oxide concentration detector of the present invention, the current leak between the electrodes of the oxygen concentration measurement cell and the second oxygen pumping cell is remarkably reduced, and the measurement accuracy of the oxygen concentration in the first void portion is improved. And the oxygen concentration in the first void portion can be controlled accurately. As a result, the oxygen concentration in the first void can be stably controlled to a low level close to the oxygen concentration at which nitrogen oxides start to decompose,
The detection accuracy of the nitrogen oxide concentration in the exhaust gas which is a very small amount is remarkably improved. The nitrogen oxide concentration detector having the above-described structure according to the present invention can produce a small-sized nitrogen oxide concentration detector with good productivity and low cost by applying the manufacturing technology of the ceramic multilayer substrate to the ceramic solid electrolyte material. , And can be provided.
【００１３】また、本発明の好ましい窒素酸化物濃度検
出器では、固体電解質層の間に設けられた絶縁膜又は絶
縁層によって、酸素濃度測定セルの電極が第１酸素ポン
ピングセル及び第２酸素ポンピングセルの電極と電気的
に絶縁されている。同じ層の固体電解質に２つ以上の酸
素濃度セルが設けられている従来の窒素酸化物濃度検出
器では電極間が互いに完全に絶縁されていないが、本発
明の窒素酸化物濃度検出器ではこれが可能であり、固体
電解質層の間に設けた絶縁膜又は絶縁層によって電極相
互間の電流リークを完全に防げる。In the preferred nitrogen oxide concentration detector of the present invention, the electrodes of the oxygen concentration measuring cell are connected to the first oxygen pumping cell and the second oxygen pumping by the insulating film or the insulating layer provided between the solid electrolyte layers. It is electrically insulated from the cell electrodes. In a conventional nitrogen oxide concentration detector in which two or more oxygen concentration cells are provided in the same layer of solid electrolyte, the electrodes are not completely insulated from each other, but in the nitrogen oxide concentration detector of the present invention, this is not the case. It is possible, and the current leak between the electrodes can be completely prevented by the insulating film or the insulating layer provided between the solid electrolyte layers.
【００１４】このような構成とした窒素酸化物濃度検出
器では、酸素濃度測定セルの測定精度が向上し、第１空
隙部の酸素濃度を精度よく制御できるので窒素酸化物濃
度検出器の窒素酸化物濃度の検出精度がさらに向上し、
低濃度の窒素酸化物濃度も精度よく検出できる。絶縁膜
はすべての固体電解質層の間に設けてもよいが、絶縁を
必要とする固体電解質層の間にだけ設けるのが好まし
い。また、絶縁膜を設ける代わりに、酸素セルを設けな
い固体電解質層をアルミナなどの絶縁層で置き換えても
よい。In the nitrogen oxide concentration detector having such a configuration, the measurement accuracy of the oxygen concentration measurement cell is improved, and the oxygen concentration in the first gap can be controlled with high accuracy. The detection accuracy of substance concentration is further improved,
Even low concentrations of nitrogen oxides can be accurately detected. The insulating film may be provided between all the solid electrolyte layers, but is preferably provided only between the solid electrolyte layers requiring insulation. Instead of providing an insulating film, a solid electrolyte layer without an oxygen cell may be replaced with an insulating layer such as alumina.
【００１５】本発明の他の好ましい窒素酸化物濃度検出
器では、第２空隙部が多孔質材料で充填されている。た
とえば、第２拡散通路と第２空隙部に同じ多孔質材料が
充填されており、これによって第２空隙部の有効容積が
顕著に小さくなる。第２空隙部の有効容積が小さくなれ
ば、窒素酸化物検出器が窒素酸化物を検知する応答性が
顕著に向上する。この第２空隙部の容積は、０．１ｍｍ
3以下、あるいは第１空隙部の５０％以下とするのが好
ましい。In another preferred nitrogen oxide concentration detector of the present invention, the second void is filled with a porous material. For example, the second diffusion passage and the second gap are filled with the same porous material, so that the effective volume of the second gap is significantly reduced. When the effective volume of the second gap is reduced, the responsiveness of the nitrogen oxide detector to detect nitrogen oxide is significantly improved. The volume of the second gap is 0.1 mm
It is preferably set to 3 or less, or 50% or less of the first gap portion.
【００１６】本発明の他の好ましい窒素酸化物濃度検出
器では、第２酸素ポンピングセルの第２空隙部側に設け
た多孔質の電極が白金、ロジウム、パラジウム、イリジ
ウム、レニウムから選ばれるいずれかの金属又はその合
金からなり、他の電極が白金又は白金合金からなる。特
にロジウムを含む多孔質の電極には窒素酸化物を分解す
る触媒機能があるので、検出器のセンサ部の温度をそれ
ほど高くしなくても第２空隙部中の窒素酸化物を完全に
分解でき、ｐｐｍオーダーの少ない窒素酸化物濃度を第
２酸素ポンピングセルの電流値として検出できる。な
お、第１空隙部に設けた多孔質の電極は好ましくは、白
金、ロジウム、パラジウム、イリジウム、レニウムから
選ばれるいずれかの金属又はその合金からなり、あるい
は、これらとＡｇ，Ａｕ，Ｎｉ，Ｃｏ，Ｃｒ，Ｆｅ，Ｍ
ｎ，Ｃｕ，Ｔｉ，Ａｌ，Ｐｂ，Ｚｎ，Ｓｎ，Ｉｎから選
ばれる少なくとも１種とを含有する。[0016] In another preferred nitrogen oxide concentration detector of the present invention, the porous electrode provided on the second void side of the second oxygen pumping cell is any one selected from platinum, rhodium, palladium, iridium and rhenium. And the other electrode is made of platinum or a platinum alloy. In particular, since the porous electrode containing rhodium has a catalytic function of decomposing nitrogen oxides, it is possible to completely decompose nitrogen oxides in the second void portion without increasing the temperature of the sensor portion of the detector so much. , A low nitrogen oxide concentration on the order of ppm can be detected as the current value of the second oxygen pumping cell. The porous electrode provided in the first void portion is preferably made of any metal selected from platinum, rhodium, palladium, iridium and rhenium, or an alloy thereof, or is made of Ag, Au, Ni, and Co. , Cr, Fe, M
and at least one selected from n, Cu, Ti, Al, Pb, Zn, Sn, and In.
【００１７】本発明の他の好ましい窒素酸化物濃度検出
器では、絶縁膜又は絶縁層がアルミナセラミックス（例
えば高純度アルミナ）である。アルミナセラミックスは
高温下での絶縁性が良好であり、またジルコニアの固体
電解質層との同時焼成も可能であり、さらに原料の入手
も容易である。In another preferred nitrogen oxide concentration detector of the present invention, the insulating film or the insulating layer is made of alumina ceramics (for example, high-purity alumina). Alumina ceramics have good insulation properties at high temperatures, can be co-fired with a zirconia solid electrolyte layer, and can easily obtain raw materials.
【００１８】本発明の他の好ましい窒素酸化物濃度検出
器では、窒素酸化物濃度検出器を固体電解質層に垂直な
方向に投影したとき、第１空隙部と第２空隙部とが互い
に概ね重なり合う位置にあり、第１空隙部と第２空隙部
の間の固体電解質層を貫通して固体電解質層に垂直な方
向に伸びる第２拡散通路によって第１空隙部と第２空隙
部とが連通されている。In another preferred nitrogen oxide concentration detector according to the present invention, when the nitrogen oxide concentration detector is projected in a direction perpendicular to the solid electrolyte layer, the first void and the second void substantially overlap each other. A first diffusion portion extending in a direction perpendicular to the solid electrolyte layer through the solid electrolyte layer between the first void portion and the second void portion, the first void portion and the second void portion being in communication with each other. ing.
【００１９】この構成の窒素酸化物濃度検出器では、た
とえば被測定ガスである排ガスが流れる管の管壁に設け
た穴から棒状に形成されたセンサ部を管内に挿入すると
き、センサ部の各酸素セルの管壁からの距離がほぼ等し
くなるので、熱伝導などによって検出器の長手方向に温
度勾配があっても、各酸素セル間に温度差が生じないの
で検出値に誤差がもたらされないという利点がある。ま
た、検出器の第２空隙部中の窒素酸化物を分解できるよ
うに、検出器を高温に保持する必要がある。このとき、
空隙部が互いに重なり合っているセンサ部構成を採用す
ることによって、温度保持のために付設する面状の発熱
部を有する加熱ヒータの発熱部を小さくでき、各酸素セ
ルの管壁からの距離が等しくなるので、管内の温度分布
や検出器を通しての熱伝導による温度差に影響されにく
く、検出器の各酸素セルの温度を一定温度に制御しやす
い。In the nitrogen oxide concentration detector having this configuration, for example, when a rod-shaped sensor section is inserted into a pipe through a hole formed in a pipe wall of a pipe through which an exhaust gas to be measured flows, each of the sensor sections Since the distance from the tube wall of the oxygen cell is almost equal, even if there is a temperature gradient in the longitudinal direction of the detector due to heat conduction or the like, no error occurs in the detected value because no temperature difference occurs between the oxygen cells. There is an advantage. Further, it is necessary to keep the detector at a high temperature so that the nitrogen oxide in the second void portion of the detector can be decomposed. At this time,
By adopting the sensor section configuration in which the voids overlap each other, the heating section of the heater having a planar heating section provided for maintaining the temperature can be made small, and the distance from the tube wall of each oxygen cell is equal. Therefore, the temperature of each oxygen cell of the detector is easily controlled to a constant temperature because the temperature is hardly affected by the temperature distribution in the tube and the temperature difference due to heat conduction through the detector.
【００２０】本発明の他の好ましい窒素酸化物濃度検出
器では、積層された固体電解質層に面状の発熱部を有す
る加熱ヒータを設けた層が積層され、窒素酸化物濃度検
出器を固体電解質層に垂直な方向に投影したとき、第１
空隙部、第２空隙部及び面状の発熱部が互いに概ね重な
り合う位置にある。加熱ヒータは、酸素濃度測定セルの
温度を一定値に保持し、第２空隙部の温度を高くしやす
い、互いに概ね重なり合う位置に積層するのが好まし
い。ここで面状の発熱部というのは、ヒータ線が一平面
上に屈曲して設けられているものを含む。なお、加熱ヒ
ータをたとえば２枚用いてセンサ部をその間に配置する
サンドイッチ構造にすることも好ましい。この場合加熱
ヒータと固体電解質層との間に外部に通じる空隙を設け
れば、各ポンピングセルから抜き取った酸素ガスを排出
させることができる。In another preferred nitrogen oxide concentration detector of the present invention, a layer provided with a heater having a planar heating section is laminated on the laminated solid electrolyte layer, and the nitrogen oxide concentration detector is connected to the solid electrolyte layer. When projected in a direction perpendicular to the layer, the first
The air gap, the second air gap, and the planar heat generating portion are located at positions substantially overlapping each other. The heater is preferably stacked at a position where the temperature of the oxygen concentration measurement cell is maintained at a constant value and the temperature of the second gap portion is easily increased, and the heaters are substantially overlapped with each other. Here, the planar heat generating portion includes one in which the heater wire is provided to be bent on one plane. In addition, it is also preferable to adopt a sandwich structure in which, for example, two heaters are used and the sensor unit is disposed therebetween. In this case, if an air gap communicating with the outside is provided between the heater and the solid electrolyte layer, oxygen gas extracted from each pumping cell can be discharged.
【００２１】窒素酸化物の分解温度は酸素濃度が低い程
低いが、窒素酸化物濃度検出器に付設する加熱ヒータ
は、通常酸素濃度測定セルの部分の温度を７００℃以上
に保持できるものが好ましい。この条件を充たす加熱ヒ
ータとしては、加熱ヒータの発熱部をセラミックスと白
金又は白金合金の複合材料とし、加熱ヒータのリード部
を白金又は白金合金としたものを使用するのが好まし
い。また、加熱ヒータのリード部の常温抵抗値を加熱ヒ
ータ全体の常温抵抗値の３０％以下とするのが好まし
い。リード部の抵抗値を小さくすれば、検出器を加熱す
るための電気エネルギのロスを少なくできる。The decomposition temperature of nitrogen oxides is lower as the oxygen concentration is lower, but it is preferable that the heater attached to the nitrogen oxide concentration detector can usually maintain the temperature of the oxygen concentration measurement cell at a temperature of 700 ° C. or higher. . As a heater satisfying this condition, it is preferable to use a heater whose heating part is made of a composite material of ceramics and platinum or a platinum alloy, and whose lead part is made of platinum or a platinum alloy. Further, it is preferable that the normal temperature resistance value of the lead portion of the heater be 30% or less of the normal temperature resistance value of the entire heater. If the resistance value of the lead portion is reduced, the loss of electric energy for heating the detector can be reduced.
【００２２】本発明の第２の視点における窒素酸化物濃
度の検出方法は、固体電解質層に一対の多孔質電極を備
えた第１酸素ポンピングセル及び酸素濃度測定セルを有
する第１空隙部と、固体電解質層に一対の多孔質電極を
備えた第第２酸素ポンピングセルを有する第２空隙部
と、第１空隙部を被測定ガス側と連通する第１拡散通路
と、第１空隙部を第２空隙部に連通する第２拡散通路と
を備える固体電解質層が積層されてなるとともに、第１
酸素ポンピングセル、酸素濃度測定セル及び第２酸素ポ
ンピングセルがいずれも異なる固体電解質層に設けられ
ている窒素酸化物濃度検出器を用い、第１拡散通路を通
して第１空隙部に導入した被測定ガスから窒素酸化物が
実質的に分解しない所定の低酸素濃度まで、酸素濃度測
定セルで酸素濃度を測定しつつ第１酸素ポンピングセル
によって第１空隙部から酸素を抜き取り、所定の低酸素
濃度とした被測定ガスを第２拡散通路を通して第２空隙
部に導入し、第２空隙部に設けられた第２酸素ポンピン
グセルに一定電圧を印加して第２空隙部内の被測定ガス
中の窒素酸化物を分解しつつ酸素を抜き取り、このとき
第２酸素ポンピングセルに流れるポンプ電流Ｉｐ2（μ
Ａ）に基いて被測定ガス中の窒素酸化物濃度を検出する
ことを特徴とする。A method for detecting a concentration of nitrogen oxides according to a second aspect of the present invention includes a first void having a first oxygen pumping cell having a pair of porous electrodes in a solid electrolyte layer and an oxygen concentration measuring cell; A second gap having a second oxygen pumping cell having a pair of porous electrodes in the solid electrolyte layer, a first diffusion passage communicating the first gap with the gas to be measured, and a first gap formed by the first gap. A solid electrolyte layer having a second diffusion passage communicating with the second cavity;
The gas to be measured introduced into the first void portion through the first diffusion passage using a nitrogen oxide concentration detector in which the oxygen pumping cell, the oxygen concentration measuring cell, and the second oxygen pumping cell are all provided in different solid electrolyte layers. From the first oxygen pumping cell, oxygen was extracted from the first void while measuring the oxygen concentration in the oxygen concentration measurement cell until a predetermined low oxygen concentration at which the nitrogen oxides were not substantially decomposed to obtain a predetermined low oxygen concentration The gas to be measured is introduced into the second gap through the second diffusion passage, and a constant voltage is applied to a second oxygen pumping cell provided in the second gap to cause nitrogen oxide in the gas to be measured in the second gap. Is decomposed to extract oxygen, and at this time, the pump current Ip 2 (μ
The method is characterized in that the nitrogen oxide concentration in the gas to be measured is detected based on A).
【００２３】すなわち、前述の窒素酸化物濃度検出器を
使用し、第１拡散通路を通して第１空隙部に導入された
被測定ガスから窒素酸化物が実質的に分解しない所定の
低酸素濃度まで、酸素濃度測定セルで酸素濃度を監視し
つつ第１酸素ポンピングセルによって酸素を抜き取り、
酸素を抜き取った後の一定の低酸素濃度、たとえば酸素
分圧を１０-6ａｔｍ（１００ｐｐｍ程度）とした被測定
ガスを第２拡散通路を通して第２空隙部に導入し、第２
空隙部に設けた第２酸素ポンピングセルに、第１酸素ポ
ンピングセルで印加したより高い一定電圧、例えば４５
０ｍＶを印加して第２空隙部内に導入した被測定ガス中
の窒素酸化物を分解するとともに酸素を抜き取り、この
ときの第２酸素ポンピングセルに流れる電流値から被測
定ガス中の窒素酸化物濃度を検出する。酸素分圧を一定
の低酸素濃度とするには、第１空隙部の酸素測定セルの
起電力が所定の値（例えば１５０ｍＶ）となるように、
第１酸素ポンピングセルを制御すればよい。That is, by using the above-mentioned nitrogen oxide concentration detector, the concentration of the gas to be measured introduced into the first gap through the first diffusion passage is reduced to a predetermined low oxygen concentration at which nitrogen oxides are not substantially decomposed. Oxygen is extracted by the first oxygen pumping cell while monitoring the oxygen concentration in the oxygen concentration measuring cell,
A gas to be measured having a constant low oxygen concentration, for example, an oxygen partial pressure of 10 −6 atm (approximately 100 ppm) after extracting oxygen is introduced into the second gap through the second diffusion passage,
A constant voltage higher than that applied by the first oxygen pumping cell, for example, 45, is applied to the second oxygen pumping cell provided in the gap.
By applying 0 mV to decompose nitrogen oxides in the gas to be measured introduced into the second gap and extract oxygen, the concentration of nitrogen oxides in the gas to be measured is determined from the current value flowing through the second oxygen pumping cell. Is detected. In order to set the oxygen partial pressure to a constant low oxygen concentration, the electromotive force of the oxygen measurement cell in the first gap is set to a predetermined value (for example, 150 mV).
The first oxygen pumping cell may be controlled.
【００２４】第２ポンピングセルに印加する電圧は、第
２空隙部の温度や第２空隙部内にある触媒の種類、第２
酸素ポンピングセルの電極の種類などによって変化する
が、ＣＯ2やＨ2Ｏが分解しない電圧、たとえば温度が７
００℃で電極が多孔質ロジウム（Ｒｈ）であるとき、安
定して窒素酸化物濃度が検出できるように３００〜８０
０ｍＶとするのが好ましい。The voltage applied to the second pumping cell depends on the temperature of the second gap, the type of the catalyst in the second gap, the second
The voltage varies depending on the type of the electrode of the oxygen pumping cell, but does not decompose CO 2 or H 2 O, for example, a temperature of 7
When the electrode is made of porous rhodium (Rh) at 00 ° C., 300 to 80 is used to stably detect the nitrogen oxide concentration.
Preferably, it is 0 mV.
【００２５】本発明の窒素酸化物濃度の検出方法は、従
来の検出方法と比べて酸素濃度測定セルの電極と他の酸
素セルの電極と間の電流リークが僅かであることによっ
て、好ましくは絶縁膜又は絶縁層で電極間が絶縁されて
いて電極間で電流リークがないことによって、酸素濃度
測定セルの測定精度が高い。酸素濃度測定セルの測定精
度が高いことによって、第１空隙部内の酸素濃度を窒素
酸化物が実質的に分解しない一定の低濃度に精度よく制
御でき、低酸素濃度の窒素酸化物を含む被測定ガスを第
２拡散通路から第２空隙部に送って被測定ガス中の窒素
酸化物を分解し、第２空隙部に流れる電流値から窒素酸
化物を精度よく検出できる。この検出方法で得られる検
出値は、被測定ガス中の酸素を除く介在ガスの濃度によ
って変動しない。また、被測定ガス中の酸素濃度による
変動はあまり大きくない。The method for detecting the concentration of nitrogen oxides according to the present invention is preferable because the current leakage between the electrode of the oxygen concentration measuring cell and the electrode of another oxygen cell is small as compared with the conventional detecting method. Since the electrodes are insulated by the film or the insulating layer and there is no current leak between the electrodes, the measurement accuracy of the oxygen concentration measurement cell is high. Due to the high measurement accuracy of the oxygen concentration measuring cell, the oxygen concentration in the first void can be accurately controlled to a constant low concentration at which nitrogen oxides are not substantially decomposed, and the measured object containing nitrogen oxides having a low oxygen concentration can be measured. The gas is sent from the second diffusion passage to the second gap to decompose the nitrogen oxides in the gas to be measured, and the nitrogen oxides can be accurately detected from the current value flowing through the second gap. The detection value obtained by this detection method does not vary depending on the concentration of the intervening gas other than oxygen in the gas to be measured. Further, the fluctuation due to the oxygen concentration in the gas to be measured is not so large.
【００２６】本発明の他の好ましい窒素酸化物の検出方
法は、被測定ガス中の酸素濃度が窒素酸化物濃度の検出
値に及ぼす影響を、あらかじめ酸素濃度と窒素酸化物濃
度が異なり、かつ既知である標準ガスを用いて測定した
データに基いて補正する。これによって被測定ガス中に
含まれる酸素濃度による検出値の変動を補正することが
でき、窒素酸化物の検出精度を一層向上させることがで
きる。According to another preferred method for detecting nitrogen oxides of the present invention, the influence of the oxygen concentration in the gas to be measured on the detected value of the nitrogen oxide concentration is determined in advance if the oxygen concentration and the nitrogen oxide concentration are different from each other. Is corrected based on the data measured using the standard gas of This makes it possible to correct the fluctuation of the detection value due to the concentration of oxygen contained in the gas to be measured, and to further improve the detection accuracy of nitrogen oxides.
【００２７】本発明の他の好ましい窒素酸化物の検知方
法は、前記データが、前記標準ガスを用いて酸素濃度測
定セルで第１空隙部内の酸素濃度を監視しつつ第１酸素
ポンピングセルで第１空隙部内の酸素濃度を窒素酸化物
が実質的に分解されない低濃度に保つときの被測定ガス
中の酸素濃度（％）と第１酸素ポンピングセルのポンプ
電流Ｉｐ1（μＡ）との関係、窒素酸化物濃度がゼロの
ときのＯ2濃度（％）と第２空隙部から酸素を抜き取る
第２酸素ポンピングセルのポンプ電流Ｉｐ2o（μＡ）と
の関係、及び測定対象とする被測定ガスと同レベルの酸
素濃度を有し、異なる窒素酸化物濃度を有する標準ガス
について求めた窒素酸化物濃度（ｐｐｍ）と第２酸素ポ
ンピングセルのポンプ電流Ｉｐ2（μＡ）との関係であ
る。このデータは、検出器の仕様やその製造上のばらつ
き、たとえば検出器の設定温度、第１拡散通路や第２拡
散通路の通気性とその比、第１空隙部と第２空隙部の容
積とその比などによって変わるので、好ましくは各検出
器についてあらかじめ測定データを求めておく。[0027] In another preferred method for detecting nitrogen oxides of the present invention, the data is obtained by monitoring the oxygen concentration in the first void in the oxygen concentration measurement cell using the standard gas and by using the standard oxygen gas in the first oxygen pumping cell. The relationship between the oxygen concentration (%) in the gas to be measured and the pump current Ip 1 (μA) of the first oxygen pumping cell when the oxygen concentration in the void is kept at a low concentration at which nitrogen oxides are not substantially decomposed. The relationship between the O 2 concentration (%) when the nitrogen oxide concentration is zero and the pump current Ip 2 o (μA) of the second oxygen pumping cell for extracting oxygen from the second gap, and the measured gas to be measured 7 shows the relationship between the nitrogen oxide concentration (ppm) obtained for a standard gas having the same level of oxygen concentration and a different nitrogen oxide concentration and the pump current Ip 2 (μA) of the second oxygen pumping cell. This data is based on the specifications of the detector and its manufacturing variations, such as the set temperature of the detector, the air permeability and the ratio of the first diffusion passage and the second diffusion passage, and the volume of the first and second voids. Since the ratio varies depending on the ratio or the like, preferably, measurement data is preferably obtained in advance for each detector.
【００２８】本発明の他の好ましい窒素酸化物の検出方
法は、被測定ガス中の酸素濃度が変化しても、窒素酸化
物濃度（ｐｐｍ）とポンプ電流Ｉｐ2（μＡ）の間に所
定の函数関係（例えば直線関係）があると仮定し、あら
かじめマイクロコンピュータのメモリーに蓄積した前記
データに基きマイクロコンピュータで演算して補正した
窒素酸化物濃度を求め、ディスプレイに表示又は記録計
に出力する。検出値の補正演算を検出器に付設したマイ
クロコンピュータによって行なえば、補正された精度の
よい検出値をオンタイムで得ることができ、得られた検
出値を表示あるいは記録できる他、内燃機関などの燃焼
装置の制御部にこの検出値をフィードバックして燃焼装
置の運転状態の制御に使用できる。Another preferred method for detecting nitrogen oxides according to the present invention is that a predetermined nitrogen oxide concentration (ppm) and a pump current Ip 2 (μA) are maintained even when the oxygen concentration in the gas to be measured changes. Assuming that there is a function relationship (for example, a linear relationship), the microcomputer calculates a corrected nitrogen oxide concentration based on the data previously stored in the memory of the microcomputer, and displays the corrected nitrogen oxide concentration on a display or outputs it to a recorder. If the correction calculation of the detected value is performed by a microcomputer attached to the detector, a corrected and accurate detected value can be obtained on-time, and the obtained detected value can be displayed or recorded. The detected value is fed back to the control unit of the combustion device and can be used for controlling the operation state of the combustion device.
【００２９】ここで、本発明の一実施形態に係る窒素酸
化物濃度検出器の測定原理を説明する。図１６は、本発
明の一実施形態に係る窒素酸化物濃度検出器の測定原理
を説明するための概略構成図であって、検出器を短手方
向に沿って切断した断面図である。図１６に示した検出
器においては、固体電解質層と該層を挟んで設けられた
一対の酸素イオンポンプ電極を備えた第１酸素イオンポ
ンプセル（第１酸素ポンピングセル）６の層、第１測定
室（第１空隙部）２の層、固体電解質層と該層を挟んで
設けられた一対の酸素分圧検知電極を備えた酸素濃度測
定セル７の層、固体電解質の層、第２測定室（第２空隙
部）４の層、及び固体電解質層と該層を挟んで設けられ
た一対の酸素イオンポンプ電極を備えた第２酸素イオン
ポンプセル（第２酸素ポンピングセル）８の層の順に積
層され、さらに、第１測定室２の両側には第１拡散孔
（第１拡散通路）１が設けられ、第１測定室２と第２測
定室４の間には、酸素濃度測定セル７の層及び固体電解
質の層を貫通して両室２，４を連通する第２拡散孔（第
２拡散通路）３が設けられている。Here, the measurement principle of the nitrogen oxide concentration detector according to one embodiment of the present invention will be described. FIG. 16 is a schematic configuration diagram for explaining a measurement principle of the nitrogen oxide concentration detector according to one embodiment of the present invention, and is a cross-sectional view of the detector cut along a lateral direction. In the detector shown in FIG. 16, a layer of a first oxygen ion pump cell (first oxygen pumping cell) 6 including a solid electrolyte layer and a pair of oxygen ion pump electrodes provided with the layer interposed therebetween, The layer of the measurement chamber (first void) 2, the layer of the oxygen concentration measurement cell 7 including the solid electrolyte layer and a pair of oxygen partial pressure detection electrodes provided with the layer interposed therebetween, the layer of the solid electrolyte, the second measurement Of the layer of the chamber (second void portion) 4 and the layer of the second oxygen ion pump cell (second oxygen pumping cell) 8 including the solid electrolyte layer and a pair of oxygen ion pump electrodes provided with the layer interposed therebetween. The first measurement chamber 2 is provided with first diffusion holes (first diffusion passages) 1 on both sides thereof, and an oxygen concentration measurement cell is provided between the first measurement chamber 2 and the second measurement chamber 4. 7 and the second diffusion hole (the second diffusion hole) penetrating the solid electrolyte Diffusion path) 3 is provided.
【００３０】次ぎに、図１６に示した窒素酸化物濃度検
出器の測定原理を説明する。先ず、(ａ)排気ガスが第１
拡散孔１を通って第１測定室２に拡散する。(ｂ)第１酸
素イオンポンプセル６により、第１測定室２に流入した
排気ガス中の酸素を、ＮＯXが実質的に分解しない程度
にまで外部へ汲み出す。このとき、酸素分圧検知電極
（酸素濃度測定セル７の電極）から出力される信号に基
いて、第１酸素イオンポンプセル６を駆動して、第１測
定室２内の酸素分圧を一定に制御する。(ｃ)第１測定室
２から、第２拡散孔３を通って、第２測定室４へ、濃度
制御されたＯ2ガスと、ＮＯXガスとが拡散する。(ｄ)第
２酸素イオンポンプセル８によって、第２測定室４内の
酸素が汲み出されることにより、第２測定室４内の酸素
濃度が低下され、第２測定室４のＮＯxガスはＮ2とＯ2
とに分解される。このとき、第２酸素イオンポンプセル
８間に流れるポンプ電流Ｉｐ2の値とＮＯx濃度の値には
直線的な相関関係があるから、結局Ｉｐ2の値を測定す
ることによりＮＯx濃度が測定でき、排気ガス中の窒素
酸化物濃度を検出できることとなる。また、このような
窒素酸化物濃度検出器において、異なる固体電解質層に
酸素分圧検知電極と酸素イオンポンプ電極とをそれぞれ
設けることにより、両電極間にリーク電流が流れなくさ
れる。従って、第１測定室２内の残留酸素濃度をより正
確に測定できるようになるから、ＮＯxが分解された酸
素濃度に基づき検出されるＮＯx濃度がより正確に検出
されることとなる。Next, the measurement principle of the nitrogen oxide concentration detector shown in FIG. 16 will be described. First, (a) the exhaust gas is the first
Diffusion into the first measurement chamber 2 through the diffusion hole 1. (b) The first oxygen ion pump cell 6 pumps the oxygen in the exhaust gas flowing into the first measurement chamber 2 to the outside to the extent that NO X is not substantially decomposed. At this time, the first oxygen ion pump cell 6 is driven based on the signal output from the oxygen partial pressure detection electrode (the electrode of the oxygen concentration measurement cell 7) to keep the oxygen partial pressure in the first measurement chamber 2 constant. To control. (c) O 2 gas and NO x gas whose concentration is controlled are diffused from the first measurement chamber 2 to the second measurement chamber 4 through the second diffusion holes 3. (d) The oxygen in the second measurement chamber 4 is reduced by pumping out the oxygen in the second measurement chamber 4 by the second oxygen ion pump cell 8, and the NO x gas in the second measurement chamber 4 is N 2 and O 2
And is decomposed into At this time, the concentration of NO x by the linear correlation to values of the concentration of NO x pumping current Ip 2 flowing between the second oxygen ion pump cell 8 to measure the value of Ip 2 eventually It is possible to measure and detect the nitrogen oxide concentration in the exhaust gas. Further, in such a nitrogen oxide concentration detector, by providing an oxygen partial pressure detection electrode and an oxygen ion pump electrode on different solid electrolyte layers, a leak current is prevented from flowing between the two electrodes. Accordingly, since so the residual oxygen concentration in the first measurement chamber 2 can be measured more accurately, so that the concentration of NO x in which NO x is detected based on the oxygen concentration which is decomposed can be more accurately detected.
【００３１】次ぎに、本発明の第３の視点に係る別の好
ましい実施形態を図１７を参照して説明する。図１７
は、被測定ガスが流入する第１測定室（第１拡散通路、
第１拡散律速部）を固体電解質層面に沿って破断した断
面を示す説明図であり、図中左側には本実施形態に係る
ＮＯxセンサ（窒素酸化物濃度検出器）、右側には比較
例のＮＯxセンサを示し、両者を対比して、本実施形態
に係るＮＯxセンサの原理を説明する。まず、図１７中
右側の比較例のＮＯxセンサにおいては、被測定ガスを
第１測定室２に流入させるための４つの第１拡散孔（第
１拡散通路）１が第２拡散孔（第２拡散通路）３の近く
に設けられ、かつ第１測定室２底面のほぼ全面に第１拡
散孔１に接して（第１測定室２の全長に対して長く）酸
素分圧検知電極７−ａが設けられている。一方、同図中
左側の実施形態のＮＯxセンサにおいては、２つの第１
拡散孔１が第２拡散孔３と大きく離間して設けられ、酸
素分圧検知電極７−ａは第１測定室２底面全体の面積に
対して小さく（第１測定室２の全長に対して短く）、第
１拡散孔１と所定距離離間して、かつ第２拡散孔３の周
囲（近傍）のみに設けられている。この実施形態のＮＯ
xセンサの“第１拡散孔が第２拡散孔と大きく離間して
設けられ、酸素分圧検知電極は第１測定室底面全体の面
積に対して小さく（第１測定室２の全長に対して短
く）、第１拡散孔１と所定距離離間して、かつ第２拡散
孔３の周囲（近傍）のみに設けられている”という特徴
は、後述の図１５に示すＮＯxセンサも備えている。Next, another preferred embodiment according to the third aspect of the present invention will be described with reference to FIG. FIG.
Is a first measurement chamber (first diffusion passage, into which the gas to be measured flows).
FIG. 4 is an explanatory view showing a cross section in which a first diffusion-controlling portion is cut along the surface of a solid electrolyte layer, wherein the left side of the figure shows a NO x sensor (nitrogen oxide concentration detector) according to the present embodiment, and the right side shows a comparative example of the NO x indicates sensor, by comparing them, to explain the principles of the NO x sensor according to the present embodiment. First, in the NO x sensor of the comparative example on the right in FIG. 17, four first diffusion hole (first diffusion path) 1 second diffusion hole for introducing the measurement gas into the first measurement chamber 2 (the (2 diffusion passage) 3, and is in contact with the first diffusion hole 1 (along the entire length of the first measurement chamber 2) over almost the entire bottom surface of the first measurement chamber 2. a is provided. On the other hand, in the NO x sensor embodiments of the left side in the figure, two first
The diffusion hole 1 is provided largely apart from the second diffusion hole 3, and the oxygen partial pressure detection electrode 7-a is small with respect to the entire area of the bottom surface of the first measurement chamber 2 (with respect to the entire length of the first measurement chamber 2). Short), provided at a predetermined distance from the first diffusion hole 1 and only around (near) the second diffusion hole 3. NO of this embodiment
The x- sensor “the first diffusion hole is provided largely apart from the second diffusion hole, and the oxygen partial pressure detection electrode is small with respect to the entire area of the bottom surface of the first measurement chamber (with respect to the entire length of the first measurement chamber 2). short), the first diffusion hole 1 and a predetermined distance apart, and wherein a "is provided only around (near) the second diffusion hole 3 is also provided with NO x sensor shown in FIG. 15 described later .
【００３２】ところで、本発明者の知見によれば、第１
に、ＮＯxセンサにおいて、第１測定室の酸素濃度は実
質的に酸素分圧検知電極上に存在する酸素濃度の平均値
で代表される。従って、第１測定室内で部分的に酸素濃
度が低い場所があったとしても、第１測定室内の酸素濃
度は酸素分圧検知電極上に存在する酸素濃度の平均値に
応じて制御されるため、実際値より高い酸素濃度が検出
されれば余分に酸素が第１測定室から汲み出されてしま
い、ＮＯxの分解が第１測定室で発生するおそれがあ
る。第２に、第１測定室において第１拡散孔付近の酸素
濃度は第１測定室の他の部分よりも高いと考えられる。
従って、第１拡散孔付近の酸素濃度が酸素分圧検知電極
による酸素濃度検出に影響を与える場合、第１酸素イオ
ンポンプセルの電圧は自動的に高められることとなる。
このような印加電圧の上昇は、通常ジルコニア製の固体
電解質層に“ブラックニング”の発生を招くから、好ま
しくない。第３に、被測定ガスの条件変化（例えば、デ
ィーゼルエンジンの排ガスでは酸素濃度が４〜１８％に
変化する）に対する酸素分圧検知電極の出力の追随性が
低い場合、この出力を入力要素とする第１酸素イオンポ
ンプセルの制御が最適化できないため、第１測定室から
第２測定室へ送られる残留酸素濃度が変化して、第２測
定室において正確なＮＯX濃度測定ができないおそれが
ある。第４に、第１測定室においてＮＯXが分解しない
ように、及び“ブラックニング”が発生しないように、
第１測定室の酸素濃度を高めに設定することは、第２測
定室における窒素酸化物濃度測定において大きなオフセ
ットの存在を許すこととなり、このオフセットの存在が
窒素酸化物濃度測定の温度依存性、酸素濃度依存性を高
めるという問題を発生させる。According to the findings of the present inventors, the first
, In NO x sensor, the oxygen concentration in the first measuring chamber is represented in a substantially average value of the oxygen concentration present on the oxygen partial pressure detection electrode. Therefore, even if there is a place where the oxygen concentration is partially low in the first measurement chamber, the oxygen concentration in the first measurement chamber is controlled according to the average value of the oxygen concentration present on the oxygen partial pressure detection electrode. if it is detected higher oxygen concentration than the actual value will be extra oxygen is pumped out from the first measurement chamber, there is a possibility that the decomposition of the NO x is generated in the first measurement chamber. Second, the oxygen concentration near the first diffusion hole in the first measurement chamber is considered to be higher than in other parts of the first measurement chamber.
Therefore, when the oxygen concentration near the first diffusion hole affects the oxygen concentration detection by the oxygen partial pressure detection electrode, the voltage of the first oxygen ion pump cell is automatically increased.
Such an increase in the applied voltage is not preferable because it usually causes "blackening" in the zirconia solid electrolyte layer. Thirdly, if the output of the oxygen partial pressure detection electrode is low in response to a change in the condition of the gas to be measured (for example, the exhaust gas of a diesel engine changes the oxygen concentration to 4 to 18%), this output is used as an input element. since the control of the first oxygen ion pump cell that can not be optimized, from the first measurement chamber residual oxygen concentration is fed into the second measurement chamber changes, it may not be accurate nO X concentration measured in the second measurement chamber is there. Fourth, as NO X in the first measurement chamber is not decomposed, and as "blackening" does not occur,
Setting the oxygen concentration in the first measurement chamber to be higher allows a large offset in the nitrogen oxide concentration measurement in the second measurement chamber, and the presence of this offset indicates the temperature dependence of the nitrogen oxide concentration measurement, This causes a problem of increasing the oxygen concentration dependency.
【００３３】従って、前記第１〜第４の知見に基づき、
図１７中右側に示した比較例ＮＯxセンサを検証すれ
ば、その酸素分圧検知電極７−ａは、第１測定室２の底
面積（第２拡散孔の開口が形成された第１空隙部の壁
面）に比較して非常に大きく、しかも第１拡散孔１に接
して設けられているため、上述した通り、正確な窒素酸
化物濃度測定ができない等の不都合を生じる場合が考え
られる。これに対し、図１７の左側に示した実施形態の
ＮＯxセンサにおいては、酸素分圧検知電極７−ａが第
１測定室２底面全体の面積に対して小さくされ、第１拡
散孔１と離間され、かつ第２拡散孔３の周囲（近傍）の
みに設けられていることによって、前記比較例ＮＯxセ
ンサの不都合がいずれも解消されている。好ましくは、
同一平面上において、前記酸素濃度測定セルの電極と前
記第１拡散通路の出口との距離が略１．５ｍｍ以上とす
る。なお、本発明において数値範囲の記載は上下限のみ
ならず、任意の中間値も含むものとする。Therefore, based on the first to fourth findings,
If verified Comparative Example NO x sensor shown on the right side in FIG. 17, the oxygen partial pressure detection electrode 7-a is first cavity in which the bottom area of the first measurement chamber 2 (the opening of the second diffusion hole is formed Since it is very large compared to the first diffusion hole 1 and is provided in contact with the first diffusion hole 1, as described above, there may be inconveniences such as the inability to accurately measure the nitrogen oxide concentration. In contrast, in the NO x sensor of the embodiment shown in the left side of FIG. 17, the oxygen partial pressure detection electrode 7-a is smaller than the area of the entire first measurement chamber 2 bottom, a first diffusion hole 1 The inconvenience of the comparative example NO x sensor is eliminated by being separated and provided only around (near) the second diffusion hole 3. Preferably,
On the same plane, the distance between the electrode of the oxygen concentration measurement cell and the outlet of the first diffusion passage is approximately 1.5 mm or more. In the present invention, the description of the numerical range includes not only the upper and lower limits but also any intermediate value.
【００３４】[0034]
【実施例】以下、本発明を実施例の図面に基いて具体的
に説明するが、本発明は以下の実施例に限定されない。DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings of embodiments, but the present invention is not limited to the following embodiments.
【００３５】［実施例１］図１は、本発明の一実施例で
ある窒素酸化物濃度検出器の先端部分の縦断面図であ
る。同図において、１は第１拡散通路、２は第１空隙
部、３は第２拡散通路、４は第２空隙部、５−１、５ー
２、５−３、５−４、５−５、５−６及び５−７は薄板
状ジルコニアの固体電解質層、６は第１酸素ポンピング
セル、６−ａ及び６−ｂは第１酸素ポンピングセルの多
孔質電極、７は酸素濃度測定セル、７−ａ及び７−ｂは
酸素濃度測定セルの多孔質電極、８は第２酸素ポンピン
グセル、８−ａ及び８−ｂは第２酸素ポンピングセルの
多孔質電極、９は大気導入部、１０は加熱ヒータであ
る。[Embodiment 1] FIG. 1 is a longitudinal sectional view of a tip portion of a nitrogen oxide concentration detector according to an embodiment of the present invention. In the figure, 1 is a first diffusion passage, 2 is a first gap, 3 is a second diffusion passage, 4 is a second gap, 5-1, 5-2, 5-3, 5-4, 5-. 5, 5-6 and 5-7 are thin zirconia solid electrolyte layers, 6 is a first oxygen pumping cell, 6-a and 6-b are porous electrodes of the first oxygen pumping cell, and 7 is an oxygen concentration measuring cell. , 7-a and 7-b are porous electrodes of an oxygen concentration measurement cell, 8 is a second oxygen pumping cell, 8-a and 8-b are porous electrodes of a second oxygen pumping cell, 9 is an air introduction part, Reference numeral 10 denotes a heater.
【００３６】図１に示された窒素酸化物濃度検出器の、
図３、図４に示された従来の窒素酸化物濃度検出器と異
なる点は、酸素濃度測定セル７と第２酸素ポンピングセ
ルが異なる固体電解質層５−３及び５−４に設けられて
いる点である。本発明の窒素酸化物濃度検出器では、酸
素セルがいずれも異なる固体電解質層に設けられている
ので、各酸素セルの電極間の電流リークが僅かとなり、
酸素濃度測定セル７によって測定される酸素濃度の精度
が高い。この酸素濃度測定セル７で第１空隙部１中の酸
素濃度を監視しつつ第１空隙部２から第１酸素ポンピン
グセル６で酸素を抜き取り、第１空隙部２内の酸素濃度
を窒素酸化物が実質的に分解しない低い酸素濃度、たと
えば約１００ｐｐｍに制御する。この低酸素濃度に安定
して制御できることによって、窒素酸化物濃度の低い被
測定ガス中の窒素酸化物濃度を精度よく検出できる。The nitrogen oxide concentration detector shown in FIG.
The difference from the conventional nitrogen oxide concentration detector shown in FIGS. 3 and 4 is that the oxygen concentration measurement cell 7 and the second oxygen pumping cell are provided in different solid electrolyte layers 5-3 and 5-4. Is a point. In the nitrogen oxide concentration detector of the present invention, since all oxygen cells are provided in different solid electrolyte layers, current leakage between the electrodes of each oxygen cell becomes small,
The accuracy of the oxygen concentration measured by the oxygen concentration measuring cell 7 is high. While monitoring the oxygen concentration in the first gap 1 with the oxygen concentration measuring cell 7, oxygen is extracted from the first gap 2 with the first oxygen pumping cell 6, and the oxygen concentration in the first gap 2 is determined as nitrogen oxide. Is controlled to a low oxygen concentration that does not substantially decompose, for example, about 100 ppm. By being able to stably control the low oxygen concentration, the nitrogen oxide concentration in the gas to be measured having a low nitrogen oxide concentration can be accurately detected.
【００３７】すなわち、次いで酸素濃度の低いこの被測
定ガスを、第２拡散通路３から第２空隙部４に送って第
２空隙部４中の被測定ガスから第２酸素ポンピングセル
８で酸素を抜き取る。第２空隙部内４の酸素濃度を窒素
酸化物が分解する濃度にまで下げると、２ＮＯX→Ｎ2＋
ＸＯ2の分解反応が起き、生成したＯ2が第２酸素ポンピ
ングセル８によって抜き取られる。このとき抜き取られ
るＯ2のほとんどは前記分解反応で生成したＯ2であるの
で、第２酸素ポンピングセル８に流れる電流値を測定す
れば、被測定ガス中の窒素酸化物濃度を検出できる。That is, the gas to be measured having a low oxygen concentration is then sent from the second diffusion passage 3 to the second gap 4, and oxygen is supplied from the gas to be measured in the second gap 4 by the second oxygen pumping cell 8. Remove it. When the oxygen concentration in the second gap 4 is reduced to a concentration at which nitrogen oxides are decomposed, 2NO x → N 2 +
The decomposition reaction of XO 2 occurs, and the generated O 2 is extracted by the second oxygen pumping cell 8. Since most of the O 2 being withdrawn at this time is the O 2 generated by the decomposition reaction, by measuring the current flowing through the second oxygen pumping cell 8, it can detect the NOx concentration in the measurement gas.
【００３８】このとき、第２空隙部４中の酸素濃度はＣ
Ｏ2やＨ2Ｏが分解するほど低い濃度にしないようにして
ＮＯを分解するためには、たとえば４５０ｍＶの定電圧
を第２酸素ポンピングセル８に印加する。この窒素酸化
物濃度の測定方法では、被測定ガスと第１酸素ポンピン
グセル６と第２酸素ポンピングセル８の温度、第１拡散
通路１及び第２拡散通路３のガス拡散抵抗、第１空隙部
２の設定酸素濃度、第２酸素ポンピングセル８の設定電
圧などによって第２酸素ポンピングセル８に流れる電流
値が変化するので、あらかじめガス濃度が既知の標準ガ
スを用いて較正しておく。この窒素酸化物濃度検出器の
寸法は、たとえば高さ（固体電解質層に垂直な方向）が
１．７ｍｍ、幅３．５ｍｍ、長さ７ｍｍである。At this time, the oxygen concentration in the second gap 4 is C
In order to decompose NO without keeping the concentration low enough to decompose O 2 and H 2 O, a constant voltage of, for example, 450 mV is applied to the second oxygen pumping cell 8. In this method for measuring the nitrogen oxide concentration, the gas to be measured, the temperature of the first oxygen pumping cell 6 and the temperature of the second oxygen pumping cell 8, the gas diffusion resistance of the first diffusion passage 1 and the second diffusion passage 3, the first void portion Since the current value flowing through the second oxygen pumping cell 8 changes depending on the set oxygen concentration of 2, the set voltage of the second oxygen pumping cell 8, and the like, calibration is performed in advance using a standard gas whose gas concentration is known. The dimensions of the nitrogen oxide concentration detector are, for example, a height (in a direction perpendicular to the solid electrolyte layer) of 1.7 mm, a width of 3.5 mm, and a length of 7 mm.
【００３９】なお、第２酸素ポンピングセル８に印加す
る電圧を適宜設定することにより、ＮＯX以外のガス
（例えばＣＯXやＨ2Ｏ、ＨＣなど）を選択時に分解させ
れば、他のガスの測定にも利用可能である。これらの設
定条件をマイクロコンピュータに記憶させておけば、Ｏ
2，ＮＯX，Ｈ2Ｏ，ＣＯ2等の多成分ガスを１個の検出器
で測定することも可能となる。It should be noted, by setting the voltage applied to the second oxygen pumping cell 8 as appropriate, gases other than NO X (e.g. CO X and H 2 O, HC, etc.) if caused to decompose when selecting the other gas It can also be used for measurement. If these setting conditions are stored in the microcomputer, O
2, NO X, it is possible to measure H 2 O, the multi-component gas such as CO 2 in one detector.
【００４０】［実施例２］図２の実施例２の図１の実施
例と異なる点は、固体電解質５−１と５−２の間及び固
体電解質５−３と５−４の間に絶縁膜１１−１と１１−
２が配置されている点と、第２空隙部４が多孔質材料で
充填されている点である。実施例２では、実施例１と同
じ機能を有する部分に同じ符号を付して説明を省略した
（以下同じ）。この実施例では、厚さ２０〜３０μｍの
高純度アルミナの絶縁膜１１−１及び１１−２が固体電
解質層の間に配置されていることによって酸素濃度測定
セル７の電極７−ａ、７−ｂと、第２酸素ポンピングセ
ル８の電極８−ａ、８−ｂの間のリーク電流を完全に防
止しているので、酸素濃度測定セル７の測定精度が高
く、第１空隙部２内の酸素濃度を低い一定濃度に安定し
て保持でき、窒素酸化物濃度が低いときも高い窒素酸化
物の検出精度が得られる。Embodiment 2 Embodiment 2 of FIG. 2 is different from the embodiment of FIG. 1 in that insulation between solid electrolytes 5-1 and 5-2 and between solid electrolytes 5-3 and 5-4 are provided. Membranes 11-1 and 11-
2 and the second space 4 is filled with a porous material. In the second embodiment, portions having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted (the same applies hereinafter). In this embodiment, the electrodes 7-a, 7- of the oxygen concentration measurement cell 7 are formed by arranging insulating films 11-1 and 11-2 of high-purity alumina having a thickness of 20 to 30 μm between the solid electrolyte layers. b, and the leak current between the electrodes 8-a, 8-b of the second oxygen pumping cell 8 is completely prevented, so that the measurement accuracy of the oxygen concentration measuring cell 7 is high, and the The oxygen concentration can be stably maintained at a low constant concentration, and high detection accuracy of nitrogen oxide can be obtained even when the nitrogen oxide concentration is low.
【００４１】［実施例３］図６は本発明の窒素酸化物濃
度検出器の他の実施例、すなわち実施例３の平面図であ
る。この検出器の寸法は、高さ（固体電解質層に垂直な
方向）１．５ｍｍ、幅３．５ｍｍ、長さ５ｍｍである。
また、図７は図６の実施例のＢ−Ｂ’縦断面図である。
実施例１との相違点は、第１空隙部２と第２空隙部４が
上下方向に互いに概ね重なり合って配置されていること
である。また、第１拡散通路１は、検出器の先端側でな
く検出器の両側にあり、第２空隙部４には多孔質材料が
充填されず、固体電解質５−１、５−２、５−３、５−
４、５−５及び５−６の各相互間に絶縁膜１１−１、１
１−２、１１−３及び１１−５がそれぞれ配置されてお
り、各酸素セルの電極は互いに絶縁されている点であ
る。なお、第２空隙部４には実施例２のように多孔質材
料を充填してもよい。図７にはさらに、第１酸素ポンピ
ングセル６の電源部１５と電流計１６、酸素濃度測定セ
ル７のポテンショメータ１７、第２酸素ポンピングセル
８の電源部１９と電流計１８及び記録計２１を備えたマ
イクロコンピュータ２０が付設されている。この検出器
の酸素濃度測定セル７の基準酸素濃度は、電極７−ｂと
そのリード線が多孔質であることによって外部の空気に
所定の拡散抵抗を介して連通されている。また、酸素濃
度測定セル７に一定の微小電流を流す構成にすれば、電
極７−ｂを自己生成基準極として、使用できる。この自
己生成基準極の利点は基準とする酸素濃度が空気中の酸
素濃度の変化に影響されにくいことである。Third Embodiment FIG. 6 is a plan view of another embodiment of the nitrogen oxide concentration detector according to the present invention, that is, a third embodiment. The dimensions of this detector are 1.5 mm in height (in the direction perpendicular to the solid electrolyte layer), 3.5 mm in width, and 5 mm in length.
FIG. 7 is a vertical sectional view taken along the line BB 'of the embodiment of FIG.
The difference from the first embodiment is that the first gap 2 and the second gap 4 are arranged so as to substantially overlap each other in the vertical direction. Further, the first diffusion passage 1 is not on the tip side of the detector but on both sides of the detector, and the second gap portion 4 is not filled with a porous material, and the solid electrolytes 5-1 5-2, and 5- 3,5-
4, 5-5 and 5-6, the insulating films 11-1, 1
1-2, 11-3, and 11-5 are respectively arranged, and the point of this is that the electrodes of each oxygen cell are insulated from each other. The second gap 4 may be filled with a porous material as in the second embodiment. FIG. 7 further includes a power supply unit 15 and an ammeter 16 of the first oxygen pumping cell 6, a potentiometer 17 of the oxygen concentration measurement cell 7, a power supply unit 19 of the second oxygen pumping cell 8, an ammeter 18, and a recorder 21. A microcomputer 20 is additionally provided. The reference oxygen concentration of the oxygen concentration measuring cell 7 of this detector is communicated to the outside air via a predetermined diffusion resistance because the electrode 7-b and its lead wire are porous. In addition, if a configuration in which a constant minute current is applied to the oxygen concentration measurement cell 7 is used, the electrode 7-b can be used as a self-generated reference electrode. The advantage of this self-generated reference electrode is that the reference oxygen concentration is less susceptible to changes in the oxygen concentration in the air.
【００４２】［実施例４］図８は、本発明の実施例に係
る窒素酸化物濃度検出器を製造するときのレイアウトの
一例を示す斜視図である。この場合、酸素濃度測定セル
７に微小な一定電流を流せば電極７−ｂを自己生成基準
極として使用可能である。Embodiment 4 FIG. 8 is a perspective view showing an example of a layout when manufacturing a nitrogen oxide concentration detector according to an embodiment of the present invention. In this case, if a small constant current is passed through the oxygen concentration measuring cell 7, the electrode 7-b can be used as a self-generated reference electrode.
【００４３】図９は図６や図８の窒素酸化物濃度検出器
に積層して使用する加熱ヒータであり、この加熱ヒータ
２４は固体電解質層５−７上にスクリーン印刷されたア
ルミナと白金の複合材料からなる発熱部２２と、白金の
リード線２３からなる。この加熱ヒータ２４は、たとえ
ば図６に示された検出器の下方に積層され、一体化され
る。この発熱部２２は第１空隙部２及び第２空隙部４と
固体電解質層に垂直方向に投影したとき互いに概ね重な
り合っている。この例では、加熱ヒータ２４は高純度ア
ルミナの絶縁膜１１−６に挟まれており、第２酸素ポン
ピングセルの電極とは絶縁されている。FIG. 9 shows a heater which is used by being laminated on the nitrogen oxide concentration detector shown in FIGS. 6 and 8. This heater 24 is made of alumina and platinum screen-printed on the solid electrolyte layer 5-7. It comprises a heating section 22 made of a composite material and a lead wire 23 made of platinum. The heater 24 is, for example, stacked below and integrated with the detector shown in FIG. The heat generating portion 22 substantially overlaps with the first gap portion 2 and the second gap portion 4 when projected onto the solid electrolyte layer in the vertical direction. In this example, the heater 24 is sandwiched between insulating films 11-6 of high-purity alumina, and is insulated from the electrodes of the second oxygen pumping cell.
【００４４】［試験例１］実施例２の窒素酸化物濃度検
出器（図２の構成のもの）を使用し、１気圧の被測定ガ
スについての窒素酸化物の検出方法を以下に説明する。
図１０は、第１空隙部内に導入される温度が５００℃、
センサー温度が７６０℃でＣＯ2を１０％含む被測定ガ
ス中の窒素酸化物濃度を０ｐｐｍと１０００ｐｐｍに変
化させ、酸素濃度が７％、３％及び１％であるとき（残
りのガスは窒素）、第１空隙部内の酸素濃度が１ｐｐｍ
に維持されるように第１ポンピングセルが制御された際
の第１ポンピングセルに流れるポンプ電流Ｉｐ1（ｍ
Ａ）と被測定ガス中の酸素濃度との相関関係を示すグラ
フである。Test Example 1 A method for detecting nitrogen oxides in a gas to be measured at 1 atm using the nitrogen oxide concentration detector of the second embodiment (having the configuration shown in FIG. 2) will be described below.
FIG. 10 shows that the temperature introduced into the first gap is 500 ° C.
When the sensor temperature is 760 ° C. and the nitrogen oxide concentration in the gas to be measured containing 10% of CO 2 is changed to 0 ppm and 1000 ppm, and the oxygen concentration is 7%, 3% and 1% (the remaining gas is nitrogen) The oxygen concentration in the first void is 1 ppm
When the first pumping cell is controlled so as to be maintained at the same value, the pump current Ip 1 (m
3 is a graph showing a correlation between A) and an oxygen concentration in a gas to be measured.
【００４５】次に、被測定ガス中の酸素濃度を１％、３
％、７％とし、第２酸素ポンピングセルに４５０ｍＶの
電圧を印加したときに流れるポンプ電流Ｉｐ2と酸素濃
度の相関関係を求め図１１に示した。図１１のグラフか
ら、窒素酸化物濃度がゼロのときの第２酸素ポンピング
セルの電流値Ｉｐ2oを求めることができる。他方、窒素
酸化物濃度とポンプ電流Ｉｐ2の間には、図１２に示す
所定の函数関係（この例では直線関係）があるので、あ
らかじめ図１０と図１１に示されるデータを求めておけ
ば、第１酸素ポンピングセルのポンプ電流Ｉｐ1から被
測定ガス中の酸素が求められ、図１１からその酸素濃度
のときのＩｐ2oを求めることができる。Ｉｐ2oが決まれ
ば、図１２のグラフにポンプ電流Ｉｐ2と窒素酸化物濃
度との関係を示すほぼ直線状の函数曲線を引くことがで
きるので、ポンプ電流Ｉｐ2に基いて補正された精度の
よい窒素酸化物濃度を検出することができる。なお、図
１１に示すポンプ電流Ｉｐ2と酸素濃度との関係は窒素
酸化物濃度検出器の設計仕様によっては図１３に示すよ
うな場合もあるが、ポンプ電流Ｉｐ1から求めた酸素濃
度を用いて補正すれば良い点については同じである。Next, the oxygen concentration in the gas to be measured is set to 1%, 3
%, And 7%, as shown in pumping current Ip 2 and obtains 11 the correlation between the oxygen concentration flowing when a voltage is applied to the 450mV to the second oxygen pumping cell. From the graph of FIG. 11, the current value Ip 2 o of the second oxygen pumping cell when the nitrogen oxide concentration is zero can be obtained. On the other hand, since there is a predetermined function relationship (a linear relationship in this example) shown in FIG. 12 between the nitrogen oxide concentration and the pump current Ip 2 , the data shown in FIG. 10 and FIG. , oxygen in the measurement gas is obtained from the pump current Ip 1 of the first oxygen pumping cell, it can be determined Ip 2 o when the oxygen concentration of 11. If Ip 2 o is determined, a substantially linear function curve showing the relationship between the pump current Ip 2 and the nitrogen oxide concentration can be drawn in the graph of FIG. 12, so that the accuracy corrected based on the pump current Ip 2 A good nitrogen oxide concentration can be detected. Although the relationship between the pump current Ip 2 and an oxygen concentration shown in Figure 11 is also shown in FIG. 13 depending on the design specifications of the nitrogen oxide concentration sensor, using an oxygen concentration obtained from the pump current Ip 1 The same is true for the correction.
【００４６】［試験例２］図１４は実施例における窒素
酸化物濃度検出器の使用状況を説明するためのグラフで
あり、縦軸が第１空隙部内及び第２空隙部内の温度
（℃）、横軸が−ｌｏｇ［Ｏ2］で表される酸素濃度
（％）である。そして図中の領域Ａが窒素酸化物が安定
な領域、領域Ｂが窒素酸化物が分解する領域である。図
１４の横方向の一点鎖線は酸素ポンピングセルが作動で
きる下限温度、△Ｔａは温度差が小さい検出器の、△Ｔ
ｂは温度差が大きい検出器の第１空隙部内に存在する温
度差の範囲である。また、［Ｏ2］1は第１空隙部内の酸
素濃度の制御範囲、［Ｏ2］2は第２空隙部内の酸素濃度
の範囲である。[Test Example 2] FIG. 14 is a graph for explaining the use state of the nitrogen oxide concentration detector in the embodiment, in which the vertical axis represents the temperature (° C.) in the first and second voids, the horizontal axis is oxygen concentration (%) represented by -log [O 2]. A region A in the figure is a region where the nitrogen oxide is stable, and a region B is a region where the nitrogen oxide is decomposed. The dashed line in the horizontal direction in FIG. 14 indicates the lower limit temperature at which the oxygen pumping cell can operate, and ΔTa indicates ΔT of the detector having a small temperature difference.
b is the range of the temperature difference existing in the first gap of the detector having a large temperature difference. [O 2 ] 1 is a control range of the oxygen concentration in the first void, and [O 2 ] 2 is a range of the oxygen concentration in the second void.
【００４７】酸素濃淡電池の場合、酸素セルの電極間に
発生する起電力ｅは、ファラデー常数をＦ、１モル当た
りの気体常数をＲ、絶対温度をＴ、両極の酸素分圧をそ
れぞれＰ1、Ｐ2とするとき、ｅ＝−（ＲＴ／ｎＦ）ｌｎ
（Ｐ1／Ｐ2）で表される。酸素濃度測定セルでは、たと
えば空気中の酸素分圧を基準にして第１空隙部内の酸素
濃度を測定する。In the case of an oxygen concentration cell, the electromotive force e generated between the electrodes of the oxygen cell is Faraday constant, F is gas constant per mole, R is absolute temperature, T is oxygen temperature, and oxygen partial pressure of both electrodes is P 1. , P 2 , e = − (RT / nF) ln
(P 1 / P 2 ). In the oxygen concentration measuring cell, the oxygen concentration in the first gap is measured, for example, based on the oxygen partial pressure in the air.
【００４８】図２の実施例２や図６、図７の実施例３の
窒素酸化物濃度検出器では、酸素濃度測定セルの電極と
第２酸素ポンピングセルの電極との間に電流リークがな
いので、第１空隙部内の酸素濃度を精度よく制御でき、
これによって第１空隙部内の酸素濃度を狭い範囲の一定
値に制御できる。第１空隙部内の酸素濃度がばらつく
と、ばらつきがそのまま窒素酸化物濃度の検出値に影響
し、第１空隙部内の酸素濃度の変動量が即誤差となる。
たとえば、第１空隙部内の酸素濃度が１ｐｐｍ変動した
とすると、数ｐｐｍ程度の窒素酸化物濃度を検出すると
きの誤差としては影響が大きい。実施例２の窒素酸化物
濃度検出器では、第１空隙部内の酸素濃度のばらつきを
±０．０１ｐｐｍ程度以内に制御できる。また、第２空
隙部４が多孔質材料で充填されていれば、第２空隙部の
有効容積が小さく、第２酸素ポンピンセルのポンプ電流
Ｉｐ1が短時間で平衡値に到達する。したがって、窒素
酸化物濃度を検出するときの応答性が良好である。In the nitrogen oxide concentration detector according to the second embodiment shown in FIG. 2 or the third embodiment shown in FIGS. 6 and 7, there is no current leak between the electrode of the oxygen concentration measuring cell and the electrode of the second oxygen pumping cell. Therefore, it is possible to accurately control the oxygen concentration in the first void portion,
Thereby, the oxygen concentration in the first gap can be controlled to a constant value in a narrow range. When the oxygen concentration in the first gap varies, the variation directly affects the detected value of the nitrogen oxide concentration, and the amount of change in the oxygen concentration in the first gap becomes an immediate error.
For example, if the oxygen concentration in the first gap fluctuates by 1 ppm, an error in detecting a nitrogen oxide concentration of about several ppm has a large effect. In the nitrogen oxide concentration detector according to the second embodiment, the variation in the oxygen concentration in the first gap can be controlled within about ± 0.01 ppm. The second cavity portion 4 if it is filled with a porous material, the effective volume of the second cavity portion is small, the pump current Ip 1 of the second oxygen Ponpinseru reaches an equilibrium value in a short time. Therefore, the response when detecting the nitrogen oxide concentration is good.
【００４９】空気中の酸素分圧を基準として酸素濃度測
定セルで第１空隙部内の酸素濃度を監視しながら、第１
空隙部内の酸素濃度を所定の［Ｏ2］1に制御するときに
第１空隙部内に△Ｔａの温度のばらつきがあっても、第
１空隙部内の窒素酸化物が分解されることはない。しか
し、第１空隙部内に△Ｔｂの温度のばらつきがあると、
第１空隙部内の一部の状態が領域Ｂにはみ出て窒素酸化
物の一部が分解するため、第１空隙部内の被測定ガスを
第２拡散通路を経て第２空隙部に送って酸素濃度を［Ｏ
2］2に下げて窒素酸化物を完全に分解させても、既に窒
素酸化物の一部が既に分解していて窒素酸化物の濃度を
精度よく測定できない。While monitoring the oxygen concentration in the first gap with the oxygen concentration measuring cell based on the oxygen partial pressure in the air, the first
When the oxygen concentration in the gap is controlled to a predetermined value [O 2 ] 1 , even if the temperature of ΔTa varies in the first gap, the nitrogen oxide in the first gap is not decomposed. However, if there is a temperature variation of ΔTb in the first gap,
Since a part of the state in the first void part protrudes into the region B and a part of the nitrogen oxide is decomposed, the gas to be measured in the first void part is sent to the second void part through the second diffusion passage, and the oxygen concentration is reduced. To [O
2 ] Even if the nitrogen oxide is completely decomposed by reducing the value to 2 , the nitrogen oxide concentration cannot be measured accurately because a part of the nitrogen oxide has already been decomposed.
【００５０】［試験例３］図６と図７に示した実施例３
の窒素酸化物濃度検出器を、被測定ガスが流れるガソリ
ン内燃機関の排ガス管に設けた穴から挿入し、窒素酸化
物濃度を検出した。この検出器では、検出器を固体電解
質層に垂直な方向に投影したとき、第１空隙部、第２空
隙部及び発熱部が互いに概ね重なり合う位置にあるの
で、管の壁に設けた穴から検出器の測定部を管内に挿入
して管内を流れる被測定ガスの窒素酸化物濃度を検出す
るとき、第１空隙部、第２空隙部及び酸素濃度測定セル
が管の壁からほぼ等距離にあり、管内の温度分布に起因
する温度差がほとんど発生しないことが分かった。[Test Example 3] Example 3 shown in FIGS. 6 and 7
Was inserted through a hole provided in an exhaust gas pipe of a gasoline internal combustion engine through which a gas to be measured flows, and the nitrogen oxide concentration was detected. In this detector, when the detector is projected in the direction perpendicular to the solid electrolyte layer, the first gap, the second gap, and the heat generating portion are located at positions substantially overlapping each other. When the measuring part of the measuring instrument is inserted into the pipe and the nitrogen oxide concentration of the gas to be measured flowing in the pipe is detected, the first gap, the second gap and the oxygen concentration measuring cell are substantially equidistant from the pipe wall. It was found that there was almost no temperature difference caused by the temperature distribution in the tube.
【００５１】また、第１空隙部が細長くない形状とされ
ているので、第１空隙部内における温度差が小さく、第
１空隙部中の酸素濃度を高精度に制御できた。これによ
って所定の低酸素濃度になった被測定ガスを第２拡散通
路から第２空隙部に送って被測定ガス中の窒素酸化物濃
度が検出されるので、窒素酸化物濃度を高精度に検出で
きた。また、加熱ヒータの面状の発熱部が第１空隙部、
第２空隙部及び酸素濃度測定セルと投影図上で重なり合
う位置にあるので、検出器のセンサー部の加熱が容易で
あり、センサー部の温度を所定値に保持するのに要する
加熱ヒータの消費電力量を節減できることが分かった。
なお、図９に示した構成の加熱ヒータを２枚用いてセン
サ部を間に配置するサンドイッチ構造とすることも好ま
しく、図１５にその一例を示す。上下の加熱ヒータ３２
と第１、第２ポンピングセルとの間には、外気に連通す
る排気通路３１が設けられ、各ポンピングセルから抜き
取った酸素ガスを排出できる。加熱ヒータ３２の基部は
セメント等の接着層３３で各ポンピングセルの基部に接
着される。なお、酸素濃度測定セル７の第１測定室に対
向する側の電極は内部基準電極をなし、その多孔質電極
と多孔質リード部を介して外気に連通される。Further, since the first gap is not elongated, the temperature difference in the first gap is small, and the oxygen concentration in the first gap can be controlled with high precision. As a result, the gas to be measured having a predetermined low oxygen concentration is sent from the second diffusion path to the second gap, and the nitrogen oxide concentration in the gas to be measured is detected, so that the nitrogen oxide concentration can be detected with high accuracy. did it. Further, the planar heating portion of the heater is a first void portion,
Since the second gap and the oxygen concentration measurement cell are located on the projected position at an overlapping position, heating of the sensor of the detector is easy, and power consumption of the heater required to maintain the temperature of the sensor at a predetermined value is easy. It turns out that the amount can be saved.
Note that it is also preferable to adopt a sandwich structure in which the sensor unit is arranged between two heaters having the configuration shown in FIG. 9, and FIG. 15 shows an example thereof. Upper and lower heaters 32
An exhaust passage 31 communicating with the outside air is provided between the pumping cell and the first and second pumping cells, and can discharge oxygen gas extracted from each pumping cell. The base of the heater 32 is adhered to the base of each pumping cell with an adhesive layer 33 such as cement. The electrode of the oxygen concentration measurement cell 7 on the side facing the first measurement chamber forms an internal reference electrode, and is communicated with the outside air via the porous electrode and the porous lead.
【００５２】また、図７の実施例３に示したように、記
録計等を備えるマイクロコンピュータに検出器を接続
し、センサー部の酸素濃度や温度等の測定や制御を行な
うと同時に、出力された第１ポンプ電流Ｉｐ1と第２ポ
ンプ電流Ｉｐ2の値から、あらかじめ標準ガスについて
求めたデータに基き補正計算をマイクロコンピュータに
実行させれば、補正された精度の高い窒素酸化物濃度の
検出値がオンタイムで得られ、マイクロコンピュータを
内燃機関の制御系と接続すれば内燃機関の運転制御に即
使用できることが分かった。As shown in the third embodiment in FIG. 7, a detector is connected to a microcomputer having a recorder and the like, and the measurement and control of the oxygen concentration and the temperature of the sensor section are performed, and at the same time, the output is performed. If the microcomputer executes a correction calculation based on the data obtained in advance for the standard gas from the values of the first pump current Ip 1 and the second pump current Ip 2 , it is possible to detect the corrected and accurate nitrogen oxide concentration. The value was obtained on-time, and it was found that if the microcomputer was connected to the control system of the internal combustion engine, it could be used immediately for operation control of the internal combustion engine.
【００５３】［比較例１］図３と図４に示した構成の従
来の窒素酸化物濃度検出器を用いて窒素酸化物濃度の検
出を試みた。その結果、窒素酸化物濃度検出器を正常に
機能させられる検出器の温度の設定範囲が狭いことが分
かった。その理由は、窒素酸化物濃度検出器の第１空隙
部が細長いことによって第１空隙部内に温度差が存在す
るためであると推定された。また、低い窒素酸化物濃度
の被測定ガス中の窒素酸化物濃度を測定するときには、
従来の窒素酸化物濃度検出器の検出精度が本発明の窒素
酸化物濃度検出器の検出精度と比べて顕著に劣ることを
認めた。Comparative Example 1 Detection of the nitrogen oxide concentration was attempted using a conventional nitrogen oxide concentration detector having the structure shown in FIGS. As a result, it was found that the setting range of the temperature of the detector that allowed the nitrogen oxide concentration detector to function normally was narrow. It was presumed that the reason was that the first gap of the nitrogen oxide concentration detector was elongated and a temperature difference was present in the first gap. When measuring the nitrogen oxide concentration in the gas to be measured having a low nitrogen oxide concentration,
It was recognized that the detection accuracy of the conventional nitrogen oxide concentration detector was significantly inferior to the detection accuracy of the nitrogen oxide concentration detector of the present invention.
【００５４】［実施例５及び比較例２］図１８は、本発
明の実施例５に係る窒素酸化物濃度検出器を長手方向に
沿って切断した断面図である。図１８に示す本発明の実
施例５に係る窒素酸化物濃度検出器の特徴部分の概略構
成は、図１７の左側（実施形態のＮＯxセンサ）に図示
した通りであって、発明の実施の形態の欄で説明した通
り、第２拡散孔（第２拡散通路）３と大きく離間して、
第１拡散孔（第１拡散通路）１が計２カ所設けられ、酸
素分圧検知電極７は第１測定室２底面全体の面積に対し
て小さく（第１測定室２の全長に対して短く）、第１拡
散孔１と離間して、かつ第２拡散孔３の周囲（近傍）の
みに設けられている。一方、比較例であるタイプ４の検
出器は、図１７の右側図を参照して発明の実施の形態の
欄で説明した通り、被測定ガスを第１測定室に流入させ
るための４つの第１拡散孔１が第２拡散孔３の近くに設
けられ、第１測定室２底面のほぼ全面に第１拡散孔１に
接して酸素分圧検知電極７−ａが設けられているもので
ある。また、実施例５に係る窒素酸化物濃度検出器の構
成が、図１などに示した実施例の検出器と異なる点は、
第１拡散孔１が第１測定室２の短手方向に対向して設け
られ、第２拡散孔３が第１拡散孔１と離間して検出器
（第１測定室２）端部側に設けられ、Ｐｔ線からなるヒ
ータは別体で素子を挟むように設けられ、第１拡散孔１
と酸素分圧検知電極７との距離が所定値に規定されたこ
とである。Example 5 and Comparative Example 2 FIG. 18 is a cross-sectional view of a nitrogen oxide concentration detector according to Example 5 of the present invention cut along the longitudinal direction. A schematic configuration of a characteristic portion of the nitrogen oxide concentration sensor according to Embodiment 5 of the present invention shown in FIG. 18, be as shown on the left (NO x sensor of embodiment) of FIG. 17, the embodiment of the invention As described in the section of the form, the second diffusion hole (second diffusion path) 3 is largely separated from the second diffusion hole 3,
The first diffusion holes (first diffusion passages) 1 are provided in two places in total, and the oxygen partial pressure detecting electrode 7 is small with respect to the entire area of the bottom surface of the first measurement chamber 2 (short with respect to the entire length of the first measurement chamber 2). ), Are provided apart from the first diffusion hole 1 and only around (near) the second diffusion hole 3. On the other hand, a detector of type 4 as a comparative example has four fourth sensors for flowing the gas to be measured into the first measurement chamber, as described in the section of the embodiment of the invention with reference to the right view of FIG. One diffusion hole 1 is provided near the second diffusion hole 3, and an oxygen partial pressure detection electrode 7-a is provided on almost the entire bottom surface of the first measurement chamber 2 in contact with the first diffusion hole 1. . The configuration of the nitrogen oxide concentration detector according to the fifth embodiment is different from that of the embodiment shown in FIG.
The first diffusion hole 1 is provided to face the first measurement chamber 2 in the lateral direction, and the second diffusion hole 3 is separated from the first diffusion hole 1 and located at the end of the detector (the first measurement chamber 2). The heater made of a Pt line is provided so as to sandwich the element in a separate body.
That is, the distance between the electrode and the oxygen partial pressure detecting electrode 7 is set to a predetermined value.
【００５５】図１７の紙面上に示す第１拡散孔１と酸素
分圧検知電極７−ａとの距離Ａを表１に示す通り変えた
タイプ１〜３の検出器を作製した。比較例であるタイプ
４の検出器の形状は、第１拡散孔１及び酸素分圧検知電
極７−ａの形態、相互配置関係以外はタイプ１〜３の検
出器の形状と同一である。検出器の外形は、高さ（第２
拡散孔の延在する方向）１．３５ｍｍ、短手方向の幅
（第１拡散孔の延在する方向）４．１ｍｍ、長手方向の
長さ（第１測定室の延在する方向）４５ｍｍであり、第
１拡散孔１の図１７中上下方向の幅は２．４ｍｍ、第２
拡散孔３の孔径は１．１ｍｍである。タイプ１〜４の酸
素分圧検知電極７−ａ（図１７参照）の寸法（図１７中
上下方向×図１７中左右方向）は、タイプ１が６．９×
２．２ｍｍ、タイプ２〜４が２．０×２．２ｍｍ、厚み
はいずれも１０〜２０μｍである。Detectors of types 1 to 3 were prepared in which the distance A between the first diffusion hole 1 and the oxygen partial pressure detection electrode 7-a shown on the paper surface of FIG. The shape of a type 4 detector as a comparative example is the same as the shape of the type 1 to 3 detectors except for the form and mutual arrangement of the first diffusion hole 1 and the oxygen partial pressure detection electrode 7-a. The outer shape of the detector is the height (second
1.35 mm in width (direction in which the diffusion hole extends), 4.1 mm in the width direction (direction in which the first diffusion hole extends), and 45 mm in length in the longitudinal direction (direction in which the first measurement chamber extends). The width of the first diffusion hole 1 in the vertical direction in FIG.
The diameter of the diffusion hole 3 is 1.1 mm. The dimensions (vertical direction in FIG. 17 × horizontal direction in FIG. 17) of the oxygen partial pressure detection electrodes 7-a of types 1 to 4 (see FIG. 17) are 6.9 × for type 1.
2.2 mm, types 2 to 4 are 2.0 × 2.2 mm, and the thickness is 10 to 20 μm.
【００５６】[0056]
【表１】 [Table 1]
【００５７】［試験例４］タイプ１〜４の検出器を用い
て、酸素濃度検出電位Ｖｓ、及び第２酸素ポンピングセ
ルのポンプ電流Ｉｐ2を測定した。測定条件は、酸素濃
度検出電位Ｖｓと第２酸素ポンピングセルのポンプ電流
Ｉｐ2のゲインとの相関を測定する場合、排ガス温度を
３００℃、検出器温度を８００℃、排ガス中の酸素濃度
を７％、ＮＯ＝１５００ｐｐｍとした。酸素濃度とＩｐ
2の相関を測定する場合、排ガス温度を３００℃、検出
器温度を８００℃、排ガス中の酸素濃度を１，４及び，
７％、ＮＯ＝０ｐｐｍとした。ヒータ電力とＩｐ2の相
関を測定する場合、排ガス温度を３００℃、排ガス中の
酸素濃度を７％、ＮＯを０ｐｐｍとした。検出器温度は
ヒータ電圧（電力）により変化し、ヒータ電力１６Ｗで
検出器温度８００℃に相当する。なお、Ｉｐ2のゲイン
とは、“ＮＯ：１５００ｐｐｍ（所定濃度）を投入した
際のＩｐ2の変化量（μＡ）である”。ゲインはＮＯガ
ス濃度測定感度をあげるため高い方が好ましく、外的要
因によって変動しないことが望ましい。Ｉｐ2のオフセ
ットとは、“ＮＯを投入していない場合のＩｐ2の値
（μＡ）であり、第１測定室で汲み残した残留酸素濃度
に相当する。オフセット値はより小さい方が好ましく、
またいろいろな外的要因、例えば被測定ガス雰囲気中の
酸素濃度及び温度等の変動に対しより鈍感で変動し難い
ことが望ましい。表２及び図１９に、検出器タイプ１〜
４における酸素濃度検出電位Ｖｓと第２酸素ポンピング
セルのポンプ電流（窒素酸化物濃度検出電流）Ｉｐ2の
ゲインとの相関を示す。表３及び図２０に、検出器タイ
プ１〜４における酸素濃度とＩｐ2の相関を示す。さら
に、表４及び図２１に、ヒータ電力とＩｐ2の相関を示
す。Test Example 4 The oxygen concentration detection potential Vs and the pump current Ip 2 of the second oxygen pumping cell were measured using detectors of types 1 to 4. When measuring the correlation between the oxygen concentration detection potential Vs and the gain of the pump current Ip 2 of the second oxygen pumping cell, the exhaust gas temperature is 300 ° C., the detector temperature is 800 ° C., and the oxygen concentration in the exhaust gas is 7 %, NO = 1500 ppm. Oxygen concentration and Ip
When measuring the correlation of 2 , the exhaust gas temperature is 300 ° C., the detector temperature is 800 ° C., and the oxygen concentration in the exhaust gas is 1, 4, and.
7%, NO = 0 ppm. When measuring the correlation between the heater power and Ip 2 , the exhaust gas temperature was 300 ° C., the oxygen concentration in the exhaust gas was 7%, and NO was 0 ppm. The detector temperature changes depending on the heater voltage (power), and corresponds to a detector temperature of 800 ° C. at a heater power of 16 W. Note that the gain of Ip 2, "NO: is 1500ppm variation of Ip 2 when was charged (predetermined concentration) (.mu.A)". The gain is preferably high in order to increase the sensitivity of NO gas concentration measurement, and it is desirable that the gain does not fluctuate due to external factors. The offset of Ip 2 is “the value (μA) of Ip 2 when NO is not supplied, and corresponds to the residual oxygen concentration remaining in the first measurement chamber. The smaller the offset value, the better.
In addition, it is desirable that it is less sensitive to various external factors, for example, changes in the oxygen concentration and the temperature in the atmosphere of the gas to be measured. Table 2 and FIG.
4 shows the correlation between the oxygen concentration detection potential Vs and the gain of the pump current (nitrogen oxide concentration detection current) Ip 2 of the second oxygen pumping cell at 4. Table 3 and FIG. 20 show the correlation between the oxygen concentration and Ip 2 in the detector types 1 to 4. Further, Table 4 and FIG. 21 show the correlation between the heater power and Ip 2 .
【００５８】[0058]
【表２】 [Table 2]
【００５９】表２及び図１９に示した通り、酸素分圧検
知電極７−ａが第１拡散孔１から遠くに且つ第２拡散孔
３の周囲に小さな面積で設けられた検出器ほど、酸素濃
度検出電位Ｖｓの変化に対する第２酸素ポンピングセル
のポンプ電流Ｉｐ2のゲインの変化が小さいこと、また
ゲインが大きくＮＯガス濃度測定感度が高いことが分か
る。As shown in Table 2 and FIG. 19, a detector in which the oxygen partial pressure detecting electrode 7-a is provided farther from the first diffusion hole 1 and with a smaller area around the second diffusion hole 3 has a higher oxygen content. the change of the gain of the pump current Ip 2 of the second oxygen pumping cell to a change in the concentration detection potential Vs is small, also it can be seen gain greater NO gas concentration measuring sensitivity high.
【００６０】[0060]
【表３】 [Table 3]
【００６１】表３及び図２０に示した通り、酸素分圧検
知電極７−ａが第１拡散孔１から遠くに且つ第２拡散孔
３の周囲に小さな面積で設けられた検出器ほど、酸素濃
度に対する窒素酸化物濃度検出電流Ｉｐ2の値及び変動
が小さく外乱に影響されにくい検出器であることが分か
る。As shown in Table 3 and FIG. 20, a detector in which the oxygen partial pressure detecting electrode 7-a is provided farther from the first diffusion hole 1 and with a smaller area around the second diffusion hole 3 has a higher oxygen content. it can be seen the values and variations of the nitrogen oxide concentration detection current Ip 2 relative concentration of detector less sensitive to small disturbances.
【００６２】[0062]
【表４】 [Table 4]
【００６３】表４及び図２１に示した通り、酸素分圧検
知電極７−ａが第１拡散孔１から遠くに且つ第２拡散孔
３の周囲に小さな面積で設けられたタイプ１の検出器の
方が、素子温度に対する窒素酸化物濃度検出電流Ｉｐ2
の値及び変動が小さく、外乱に影響されにくい検出器で
あることが分かる。比較例であるタイプ４の検出器によ
れば、窒素酸化物濃度検出電流Ｉｐ2の値が大きく、素
子温度に対するＩｐ2の変動が大きくなり、しかも極小
値を有している。As shown in Table 4 and FIG. 21, a type 1 detector in which the oxygen partial pressure detecting electrode 7-a is provided with a small area far from the first diffusion hole 1 and around the second diffusion hole 3 Is the nitrogen oxide concentration detection current Ip 2 with respect to the element temperature.
It can be understood that the detector is small in the value and fluctuation of, and is not easily affected by disturbance. According to the detector of the type 4 is a comparative example, the value of the nitrogen oxide concentration detection current Ip 2 is large, the greater the variation of Ip 2 for element temperature, yet has a minimum value.
【００６４】以上の結果より、タイプ１〜４の順に（タ
イプ１の方がよい）、Ｉｐ2のゲイン変動が小さく、か
つオフセット値及びその変動が低く、素子温度変動の影
響が少なく、正確な窒素酸化物濃度測定が可能な検出器
であることが分かった。また、第１拡散孔と酸素分圧検
知電極との距離Ａ＝１．５ｍｍ以上の検出器が好まし
く、さらにＡ＝３ｍｍ以上の検出器が好ましいことが分
かった。なお、１．５ｍｍ以上の任意のＡの値を有する
検出器も好ましい。From the above results, in the order of types 1 to 4 (type 1 is better), the gain fluctuation of Ip 2 is small, the offset value and its fluctuation are low, the influence of element temperature fluctuation is small, and accurate The detector was found to be capable of measuring nitrogen oxide concentration. Further, it was found that a detector having a distance A of 1.5 mm or more between the first diffusion hole and the oxygen partial pressure detection electrode was preferable, and a detector having A of 3 mm or more was more preferable. Note that a detector having an arbitrary value of A of 1.5 mm or more is also preferable.
【００６５】また、第１測定室の長手方向（第１拡散孔
から第２拡散孔へ向かう方向、図１７中上下方向）に、
第１拡散孔と酸素分圧検出電極とを、酸素分圧検出電極
の第１測定室長手方向の長さの２／３、好ましくは同距
離以上、離間して配置することが好ましいと考えられ
る。In the longitudinal direction of the first measurement chamber (the direction from the first diffusion hole to the second diffusion hole, the vertical direction in FIG. 17),
It is considered preferable to dispose the first diffusion hole and the oxygen partial pressure detection electrode at a distance of 2/3, preferably the same distance or more, of the length of the oxygen partial pressure detection electrode in the longitudinal direction of the first measurement chamber. .
【００６６】［製造例］図１８などに示した窒素酸化物
濃度検出器の製造方法及びレイアウトを説明する。図２
２は、窒素酸化物濃度検出器の製造方法及びレイアウト
を説明するための図である。なお、図１８及び下記の説
明により、他の実施例及び比較例の検出器のレイアウト
及び製造工程も容易に理解される。[Manufacturing Example] A manufacturing method and a layout of the nitrogen oxide concentration detector shown in FIG. 18 and the like will be described. FIG.
FIG. 2 is a diagram for explaining a manufacturing method and a layout of the nitrogen oxide concentration detector. The layout and manufacturing process of the detectors of the other examples and comparative examples can be easily understood from FIG. 18 and the following description.
【００６７】図２２を参照して、図中左上から左下、そ
して右上から右下の順にＺｒＯ2シート及び電極用ペー
ストなどが積層されて、一体の検出器が作成される。絶
縁コート、電極などペースト材料は、所定のＺｒＯ2シ
ートにスクリーン印刷されることにより、積層形成され
る。次に、図２２に示したＺｒＯ2シートなど各構成部
品の製造例を説明する。Referring to FIG. 22, a ZrO 2 sheet, an electrode paste, and the like are stacked in order from the upper left to the lower left and the upper right to the lower right in the figure to form an integrated detector. The paste material such as an insulating coat and an electrode is laminated and formed by screen printing on a predetermined ZrO 2 sheet. Next, an example of manufacturing each component such as the ZrO 2 sheet shown in FIG. 22 will be described.
【００６８】［ＺｒＯ2シート成形］[ZrO 2 sheet molding]
【００６９】ＺｒＯ2粉末を600℃×２時間、大気炉にて
仮焼した。仮焼したＺｒＯ2粉末30kg、分散材150g、有
機溶剤10kg、玉石60kgをトロンメルにて調合し、約50時
間混合し、分散させ、これにバインダー４kgを有機溶剤
10kgに溶解させたものを添加し、20時間混合して10Pa・s
（パスカル・セカンド）程度の粘度を有するスラリーを
得た。このスラリーからドクターブレード法により、厚
さ0.4ｍｍ程度のＺｒＯ2グリーンシートを作成し、100
℃×１時間乾燥した。The ZrO 2 powder was calcined in an atmospheric furnace at 600 ° C. for 2 hours. 30 kg of calcined ZrO 2 powder, 150 g of dispersant, 10 kg of organic solvent, and 60 kg of cobblestone are prepared by trommel, mixed and dispersed for about 50 hours, and 4 kg of binder is added to the organic solvent.
Add what was dissolved in 10 kg, mix for 20 hours and 10 Pa
A slurry having a viscosity of about (Pascal second) was obtained. A ZrO 2 green sheet having a thickness of about 0.4 mm was prepared from this slurry by a doctor blade method,
C. × 1 hour drying.
【００７０】［印刷用ペースト］[Printing Paste]
【００７１】(１)第１酸素イオンポンプ電極ａ、酸素分
圧検出電極（酸素基準電極）ａ、第２酸素イオンポンプ
電極ａ、ｂ用： 白金粉末20g、ＺｒＯ2粉末2.8g、適量
の有機溶剤を、らいかい機（或いはポットミル）にて調
合し、４時間混合し、分散させ、これにバインダー２g
を有機溶剤20gに溶解させたものを添加し、さらに粘度
調整剤５gを添加し、４時間混合して粘度150Pa・s程度の
ペーストを作成した。(1) First oxygen ion pump electrode a, oxygen partial pressure detection electrode (oxygen reference electrode) a, second oxygen ion pump electrode a, b: platinum powder 20 g, ZrO 2 powder 2.8 g, appropriate amount of organic The solvent was mixed with a grinder (or pot mill), mixed for 4 hours, dispersed, and 2 g of binder was added.
Was dissolved in 20 g of an organic solvent, 5 g of a viscosity modifier was further added, and the mixture was mixed for 4 hours to prepare a paste having a viscosity of about 150 Pa · s.
【００７２】(２)第１酸素イオンポンプ電極ｂ、酸素分
圧検出電極（酸素基準電極）ｂ用：白金粉末19.8g、Ｚ
ｒＯ2粉末2.8kg、金粉末0.2ｇ、適量の有機溶剤を、ら
いかい機（或いはポットミル）にて調合し、４時間混合
し、分散させ、これにバインダー２gを有機溶剤20gに溶
解させたものを添加し、さらに粘度調整剤５gを添加
し、４時間混合して粘度150Pa・s程度のペーストを作成
した。(2) For the first oxygen ion pump electrode b and oxygen partial pressure detection electrode (oxygen reference electrode) b: 19.8 g of platinum powder, Z
A mixture of 2.8 kg of rO 2 powder, 0.2 g of gold powder and an appropriate amount of an organic solvent mixed with a grinder (or pot mill), mixed for 4 hours, dispersed, and dissolved 2 g of a binder in 20 g of an organic solvent. Was added, and 5 g of a viscosity modifier was further added, followed by mixing for 4 hours to prepare a paste having a viscosity of about 150 Pa · s.
【００７３】(３)絶縁コート、保護コート用： アルミ
ナ粉末50gと適量の有機溶剤を、らいかい機（或いはポ
ットミル）にて調合し、１２時間混合し、溶解させ、さ
らに粘度調整剤20gを添加し、３時間混合して粘度100Pa
・s程度のペーストを作成した。(3) For insulation coating and protective coating: 50 g of alumina powder and an appropriate amount of an organic solvent are mixed with a grinder (or pot mill), mixed for 12 hours, dissolved, and further added with 20 g of a viscosity modifier. And mix for 3 hours, viscosity 100Pa
・ Created about s paste.
【００７４】(４)Pt入り多孔質用（リード線用）： ア
ルミナ粉末10g、白金粉末1.5g、バインダ2.5g、有機溶
剤20gを、らいかい機（或いはポットミル）にて調合
し、４時間混合し、さらに粘度調整剤10gを添加し、４
時間混合して粘度100Pa・s程度のペーストを作成した。(4) For Pt-containing porous material (for lead wire): Alumina powder 10 g, platinum powder 1.5 g, binder 2.5 g, and organic solvent 20 g are mixed with a grinder (or pot mill) and mixed for 4 hours. And further add 10 g of a viscosity modifier,
After mixing for a time, a paste having a viscosity of about 100 Pa · s was prepared.
【００７５】(５)第１拡散孔用： 平均粒径２μｍ程度
のアルミナ粉末10g、バインダ2g、有機溶剤20gを、らい
かい機（或いはポットミル）にて調合し、混合し、分散
させ、さらに粘度調整剤10gを添加し、４時間混合して
粘度400Pa・s程度のペーストを作成した。(5) For the first diffusion hole: 10 g of alumina powder having an average particle diameter of about 2 μm, 2 g of a binder, and 20 g of an organic solvent are prepared by a grinder (or a pot mill), mixed, dispersed, and further dispersed in viscosity. 10 g of the adjusting agent was added and mixed for 4 hours to prepare a paste having a viscosity of about 400 Pa · s.
【００７６】(６)カーボンコート用： カーボン粉末４
g、バインダ2g、有機溶剤40gを、らいかい機（或いはポ
ットミル）にて調合し、混合し、分散させ、さらに粘度
調整剤５gを添加し、４時間混合してペーストを作成し
た。なお、カーボンコートを印刷形成することにより、
一例を挙げれば、第１酸素ポンプ電極ｂと酸素基準電極
ｂとの接触が防止される。また、カーボンコートは第１
測定室及び第２測定室を形成するために用いられる。カ
ーボンは焼成途中で焼失するので、カーボンコート層は
焼成体には存在しない。(6) For carbon coating: carbon powder 4
g, 2 g of a binder, and 40 g of an organic solvent were mixed by a grinder (or a pot mill), mixed and dispersed, 5 g of a viscosity modifier was further added, and mixed for 4 hours to prepare a paste. In addition, by printing and forming a carbon coat,
For example, contact between the first oxygen pump electrode b and the oxygen reference electrode b is prevented. In addition, the carbon coat is the first
It is used to form a measurement chamber and a second measurement chamber. Since carbon is burned off during firing, the carbon coat layer does not exist in the fired body.
【００７７】［ペレット体］[Pellets]
【００７８】第２拡散孔用： 平均粒径２μｍ程度のア
ルミナ粉末20g、バインダ８g、有機溶剤20gを、らいか
い機（或いはポットミル）にて調合し、１時間混合し、
造粒し、金型プレスにて約２t/cm2圧を加えφ1.3×0.8
ｔの円柱状のプレス成形体（グリーン状態）を作成し
た。このグリーン状態のプレス成形体を、２、３層目の
ジルコニアグリーンシートの所定箇所に挿入され、圧着
して一体化した後、焼成することにより、検出器中に第
２拡散孔を形成する。For the second diffusion hole: 20 g of alumina powder having an average particle size of about 2 μm, 8 g of a binder, and 20 g of an organic solvent are mixed with a grinder (or a pot mill) and mixed for 1 hour.
Granulate and apply a pressure of about 2 t / cm 2 with a die press.
A cylindrical press-formed body (green state) of t was prepared. The green pressed body is inserted into a predetermined portion of the zirconia green sheets of the second and third layers, integrated by pressing, and then fired to form second diffusion holes in the detector.
【００７９】［ＺｒＯ2積層方法］ ２、３層目圧着
後、第２拡散孔が貫通する部分（φ1.3）を打ち抜く。
打ち抜き後、第２拡散孔となるグリーン円柱状成形体を
埋め込み、１〜４層のＺｒＯ2シートを加圧力：５kg/cm
2、加圧時間：１分で圧着する。[ZrO 2 Laminating Method] After pressure bonding of the second and third layers, a portion (φ1.3) through which the second diffusion hole penetrates is punched.
After punching, a green columnar molded body serving as the second diffusion hole is embedded, and a 1-4 layer ZrO 2 sheet is pressed with a pressure of 5 kg / cm.
2. Pressing time: 1 minute.
【００８０】［脱脂及び焼成］ 圧着した成形体を、40
0℃×２時間脱脂し、1500℃×１時間焼成する。[Defatting and firing]
Degreasing at 0 ° C. × 2 hours and baking at 1500 ° C. × 1 hour.
【００８１】[0081]
【発明の効果】本発明の第１の視点における窒素酸化物
濃度検出器を使用すれば、酸素濃度測定セルと酸素ポン
ピングセルが異なる固体電解質層に設けられているの
で、酸素濃度測定セルの電極と酸素ポンピングセルの電
極との間に流れるリーク電流が僅か又は電極間が絶縁さ
れていることによってリーク電流が全く流れないので酸
素濃度の測定精度がよく、第１空隙部中の酸素濃度を精
度よく制御できる。これによって、被測定ガス中の窒素
酸化物の濃度が低いときにも、窒素酸化物濃度を精度よ
く実用的レベルにおいて安定して検出できる。When the nitrogen oxide concentration detector according to the first aspect of the present invention is used, since the oxygen concentration measurement cell and the oxygen pumping cell are provided in different solid electrolyte layers, the electrodes of the oxygen concentration measurement cell are used. The leak current flowing between the electrode of the oxygen pumping cell and the leak current does not flow at all because the electrode is insulated, so the oxygen concentration measurement accuracy is good, and the oxygen concentration in the first gap is accurately measured. Can control well. Thus, even when the concentration of nitrogen oxides in the gas to be measured is low, the concentration of nitrogen oxides can be detected accurately and stably at a practical level.
【００８２】また、本発明の第２の視点における窒素酸
化物濃度の検出方法によれば、被測定ガス中に含まれる
酸素濃度による窒素酸化物濃度の検出値に対する影響を
補正して除くことができ、さらに精度の高い検出値を安
定して得ることができる。また、マイクロコンピュータ
を窒素酸化物濃度検出器に付設しておくことによって、
補正された窒素酸化物濃度の検出値をオンタイムで得る
ことができ、内燃機関などの燃焼機の制御系への接続が
可能となる。Further, according to the nitrogen oxide concentration detecting method according to the second aspect of the present invention, it is possible to correct and remove the influence of the concentration of oxygen contained in the gas to be measured on the detected value of the nitrogen oxide concentration. It is possible to stably obtain a highly accurate detection value. Also, by attaching a microcomputer to the nitrogen oxide concentration detector,
The corrected detected value of the nitrogen oxide concentration can be obtained on-time, and connection to a control system of a combustor such as an internal combustion engine becomes possible.
【００８３】本発明の第３の視点によれば、酸素濃度測
定セルの電極が、前記第２拡散通路の開口が形成された
前記固体電解質層の層面であって前記第１空隙部を区画
する壁面に部分的に、かつ第２拡散通路の近傍に設けら
れたことにより、又は、少なくとも第１空隙部側の酸素
濃度測定セルの電極が、第１拡散通路から離間されて第
２拡散通路の近傍に設けられたことにより、第１測定室
の残留酸素濃度の測定が正確に行えるため、窒素酸化物
が分解しないように第１測定室の残留酸素濃度を一層低
下させることが可能となり、これにより、窒素酸化物濃
度測定の酸素濃度依存性、温度依存性を大幅に低下させ
ることができる。さらに、同一平面上において、前記酸
素濃度測定セルの電極と前記第１拡散通路の出口との距
離を所定範囲にすることにより、上記効果が確実に得ら
れる。According to a third aspect of the present invention, the electrode of the oxygen concentration measuring cell is a layer surface of the solid electrolyte layer in which the opening of the second diffusion passage is formed, and partitions the first void. By being provided partially on the wall surface and in the vicinity of the second diffusion passage, or at least the electrode of the oxygen concentration measurement cell on the first void side is separated from the first diffusion passage, and By being provided in the vicinity, the measurement of the residual oxygen concentration in the first measurement chamber can be accurately performed, so that the residual oxygen concentration in the first measurement chamber can be further reduced so that the nitrogen oxide is not decomposed. Thereby, the oxygen concentration dependency and the temperature dependency of the nitrogen oxide concentration measurement can be significantly reduced. Further, by setting the distance between the electrode of the oxygen concentration measurement cell and the outlet of the first diffusion passage in a predetermined range on the same plane, the above-mentioned effect can be obtained reliably.
【００８４】各従属請求項に本発明の好適な実施の態様
を規定した。上述の第１、第２、第３の視点における基
本的効果に、夫々の態様に基づくさらに好ましい利点・
効果が付加される。その詳細は発明の実施の形態及び実
施例に記載したのでここでは記載を省く。The preferred embodiments of the present invention are defined in the respective dependent claims. The above-described basic effects in the first, second, and third viewpoints have more preferable advantages based on the respective aspects.
An effect is added. The details have been described in the embodiments and examples of the present invention, and will not be described here.
【図１】本発明の窒素酸化物濃度検出器の一実施例を示
す縦断面図である。FIG. 1 is a longitudinal sectional view showing one embodiment of a nitrogen oxide concentration detector of the present invention.
【図２】本発明の窒素酸化物濃度検出器の他の一実施例
を示す縦断面図である。FIG. 2 is a longitudinal sectional view showing another embodiment of the nitrogen oxide concentration detector of the present invention.
【図３】従来の窒素酸化物濃度検出器の一例を示す平面
図である。FIG. 3 is a plan view showing an example of a conventional nitrogen oxide concentration detector.
【図４】図３の窒素酸化物濃度検出器のＡ−Ａ’の拡大
断面図である。FIG. 4 is an enlarged cross-sectional view of AA ′ of the nitrogen oxide concentration detector of FIG. 3;
【図５】従来の空燃比センサを中央で切断した断面を示
す斜視図である。FIG. 5 is a perspective view showing a cross section of the conventional air-fuel ratio sensor cut at the center.
【図６】本発明の窒素酸化物濃度検出器の他の一実施例
を示す平面図である。FIG. 6 is a plan view showing another embodiment of the nitrogen oxide concentration detector of the present invention.
【図７】図６のＢ−Ｂ’拡大縦断面図に制御系の系統図
を付記した図である。7 is a diagram in which a system diagram of a control system is added to the BB 'enlarged longitudinal sectional view of FIG. 6;
【図８】図６の窒素酸化物濃度検出器を製造するときの
レイアウトの斜視図である。FIG. 8 is a perspective view of a layout when the nitrogen oxide concentration detector of FIG. 6 is manufactured.
【図９】図６の窒素酸化物濃度検出器に取り付けられる
加熱ヒータの平面図である。FIG. 9 is a plan view of a heater attached to the nitrogen oxide concentration detector of FIG.
【図１０】本発明の一実施例に係る窒素酸化物濃度検出
器（図２の構成）において、異なった窒素酸化物濃度に
おける第１ポンピングセルのポンプ電流Ｉｐ1と被測定
ガス中の酸素濃度との相関関係の一例を示すグラフであ
る。FIG. 10 shows a pump current Ip 1 of the first pumping cell and an oxygen concentration in the gas to be measured at different nitrogen oxide concentrations in the nitrogen oxide concentration detector (the configuration of FIG. 2) according to one embodiment of the present invention. 6 is a graph showing an example of a correlation with the above.
【図１１】本発明の他の実施例に係る窒素酸化物濃度検
出器（図２の構成）を用い、酸素濃度と窒素酸化物濃度
を変え、第２ポンピングセルに４５０ｍＶの電圧を印加
したときの酸素濃度との相関関係の一例を示すグラフで
ある。FIG. 11 shows a case where a voltage of 450 mV is applied to the second pumping cell while changing the oxygen concentration and the nitrogen oxide concentration by using the nitrogen oxide concentration detector (the configuration of FIG. 2) according to another embodiment of the present invention. 4 is a graph showing an example of a correlation with the oxygen concentration of the present invention.
【図１２】本発明の他の実施例に係る窒素酸化物濃度検
出器（図２の構成）における、被測定ガス中の窒素酸化
物濃度とポンプ電流Ｉｐ2との関係の一例を示すグラフ
である。FIG. 12 is a graph showing an example of a relationship between a nitrogen oxide concentration in a gas to be measured and a pump current Ip 2 in a nitrogen oxide concentration detector (the configuration in FIG. 2) according to another embodiment of the present invention. is there.
【図１３】図１１の場合と異なった設計仕様の本発明の
別の実施例に係る窒素酸化物濃度検出器における、酸素
濃度とＩｐ2の相関関係の一例を示すクラフである。FIG. 13 is a graph showing an example of a correlation between oxygen concentration and Ip 2 in a nitrogen oxide concentration detector according to another embodiment of the present invention having a design specification different from that of FIG. 11;
【図１４】本発明の実施例に係る窒素酸化物濃度検出器
の使用状況を説明するためのグラフである。FIG. 14 is a graph for explaining a use state of the nitrogen oxide concentration detector according to the embodiment of the present invention.
【図１５】本発明の窒素酸化物濃度検出器の更に他の実
施例を示す断面図である。FIG. 15 is a sectional view showing still another embodiment of the nitrogen oxide concentration detector of the present invention.
【図１６】本発明の一実施形態に係る窒素酸化物濃度検
出器の測定原理を説明するための概略構成図であって、
検出器を短手方向に沿って切断した断面図である。FIG. 16 is a schematic configuration diagram for explaining the measurement principle of the nitrogen oxide concentration detector according to one embodiment of the present invention,
It is sectional drawing which cut the detector along the short direction.
【図１７】本発明の一実施形態に係る及び更に別の実施
例（実施例５）に係る窒素酸化物濃度検出器の概略構成
を説明するための、被測定ガスが流入する第１測定室を
固体電解質層面に沿って切断した断面を示す図であり、
図中左側にはこの実施例に係るＮＯxセンサ（窒素酸化
物濃度検出器）、右側には比較例（比較例２）のＮＯx
センサを示す。FIG. 17 is a first measurement chamber into which a gas to be measured flows, for explaining a schematic configuration of a nitrogen oxide concentration detector according to an embodiment of the present invention and a further example (Example 5). It is a diagram showing a cross section cut along the solid electrolyte layer surface,
NO x of the NO x sensor is on the left side in the figure according to this embodiment (nitrogen oxide concentration sensor), the comparative example to the right (Comparative Example 2)
2 shows a sensor.
【図１８】本発明の更に別の実施例（実施例５）に係る
窒素酸化物濃度検出器を長手方向に沿って切断した断面
図である。FIG. 18 is a cross-sectional view of a nitrogen oxide concentration detector according to still another embodiment (Example 5) of the present invention cut along a longitudinal direction.
【図１９】本発明の更に別の実施例（実施例５）及び比
較例に係る窒素酸化物濃度検出器による、酸素濃度検出
電位Ｖｓと第２酸素ポンピングセルのポンプ電流Ｉｐ2
のゲインとの相関を示すグラフである。FIG. 19 shows the oxygen concentration detection potential Vs and the pump current Ip 2 of the second oxygen pumping cell by the nitrogen oxide concentration detector according to still another embodiment (Example 5) and a comparative example of the present invention.
6 is a graph showing a correlation with the gain of the first embodiment.
【図２０】本発明の更に別の実施例（実施例５）及び比
較例（比較例２）に係る窒素酸化物濃度検出器による、
酸素濃度とＩｐ2の相関を示すグラフである。FIG. 20 shows a nitrogen oxide concentration detector according to still another embodiment (Example 5) and a comparative example (Comparative Example 2) of the present invention.
Is a graph showing the correlation between the oxygen concentration and Ip 2.
【図２１】本発明の更に別の実施例（実施例５）に係る
窒素酸化物濃度検出器による、ヒータ電力とＩｐ2の相
関を示すグラフである。FIG. 21 is a graph showing a correlation between heater power and Ip 2 by a nitrogen oxide concentration detector according to still another embodiment (Example 5) of the present invention.
【図２２】本発明の実施例に係る窒素酸化物濃度検出器
の製造方法及びレイアウトを説明するための図である。FIG. 22 is a diagram for explaining a manufacturing method and a layout of the nitrogen oxide concentration detector according to the embodiment of the present invention.
１：第１拡散通路、第１拡散孔 ２：第１空隙部、第１測定室 ３：第２拡散通路、第２拡散孔 ４：第２空隙部、第２測定室 ５−１、・・・、５−６、５−７：ジルコニアの固体電
解質層 ６：第１酸素ポンピングセル、第１酸素イオンポンプセ
ル ６−ａ、６−ｂ：第１酸素ポンピングセルの多孔質電極 ７：酸素濃度測定セル、 ７−ａ、７−ｂ：酸素濃度測定セルの多孔質電極、酸素
分圧検知電極 ８：第２酸素ポンピングセル、第２酸素イオンポンプセ
ル ８−ａ、８−ｂ：第２酸素ポンピングセルの多孔質電極 ９：大気導入部 １０：加熱ヒータ １１−１、・・・、１１−５、１１−６、１１−７：高
純度アルミナの絶縁膜 １２：アルミナの絶縁層 １５：第１酸素ポンピングセルの電源部 １６：第１酸素ポンピングセルの電流計 １７：ポテンショメータ １８：第２酸素ポンピングセルの電流計 １９：第２酸素ポンピングセルの電源部 ２０：マイクロコンピュータ ２１：記録計 ２２：発熱部 ２３：白金のリード線 ２４：加熱ヒータ Ａ：第１拡散孔と第１測定室内部側の酸素分圧検知電極
との距離1: first diffusion passage, first diffusion hole 2: first gap portion, first measurement chamber 3: second diffusion passage, second diffusion hole 4: second gap portion, second measurement chamber 5-1 ... -, 5-6, 5-7: zirconia solid electrolyte layer 6: first oxygen pumping cell, first oxygen ion pumping cell 6-a, 6-b: porous electrode of first oxygen pumping cell 7: oxygen concentration Measurement cell, 7-a, 7-b: porous electrode of oxygen concentration measurement cell, oxygen partial pressure detection electrode 8: second oxygen pumping cell, second oxygen ion pump cell 8-a, 8-b: second oxygen Porous electrode of pumping cell 9: Atmospheric introduction section 10: Heater 11-1,..., 11-5, 11-6, 11-7: Insulating film of high-purity alumina 12: Insulating layer of alumina 15: 1 Power supply section of oxygen pumping cell 16: Ammeter of first oxygen pumping cell 17: PO 18: Ammeter of the second oxygen pumping cell 19: Power supply of the second oxygen pumping cell 20: Microcomputer 21: Recorder 22: Heating part 23: Lead wire of platinum 24: Heater A: First diffusion hole Distance to the oxygen partial pressure detection electrode inside the first measurement chamber
───────────────────────────────────────────────────── フロントページの続き (72)発明者 石田 昇 名古屋市瑞穂区高辻町14番18号 日本特殊 陶業株式会社内 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Noboru Ishida 14-18 Takatsuji-cho, Mizuho-ku, Nagoya Japan Special Ceramics Co., Ltd.
Claims (29)
なる第１酸素ポンピングセル及び酸素濃度測定セルを有
する第１空隙部と、固体電解質層に一対の多孔質電極を
備えてなる第２酸素ポンピングセルを有する第２空隙部
と、前記第１空隙部を被測定ガス側に連通する第１拡散
通路と、前記第１空隙部を前記第２空隙部に連通する第
２拡散通路とを備える固体電解質層が積層されてなる窒
素酸化物濃度検出器であって、 前記第１酸素ポンピングセル、前記酸素濃度測定セル及
び前記第２酸素ポンピングセルがいずれも互いに異なる
固体電解質層に設けられていることを特徴とする窒素酸
化物濃度検出器。1. A solid electrolyte layer comprising a first oxygen pumping cell having a pair of porous electrodes and a first void having an oxygen concentration measuring cell, and a solid electrolyte layer having a pair of porous electrodes. A second gap having a two-oxygen pumping cell, a first diffusion passage communicating the first gap to the gas to be measured, and a second diffusion passage communicating the first gap to the second gap. A nitrogen oxide concentration detector comprising a stack of solid electrolyte layers comprising: wherein the first oxygen pumping cell, the oxygen concentration measurement cell, and the second oxygen pumping cell are all provided in different solid electrolyte layers. A nitrogen oxide concentration detector.
絶縁層によって、前記酸素濃度測定セルの電極が前記第
１酸素ポンピングセル及び前記第２酸素ポンピングセル
の電極と電気的に絶縁されている請求項１に記載の窒素
酸化物濃度検出器。2. The electrode of the oxygen concentration measuring cell is electrically insulated from the electrodes of the first oxygen pumping cell and the second oxygen pumping cell by an insulating film or an insulating layer provided between the solid electrolyte layers. The nitrogen oxide concentration detector according to claim 1, wherein:
ミックスである請求項１又は２に記載の窒素酸化物濃度
検出器。3. The nitrogen oxide concentration detector according to claim 1, wherein said insulating film or said insulating layer is made of alumina ceramics.
部の有効容積の５０％以下である請求項１〜３のいずれ
かに記載の窒素酸化物濃度検出器。4. The nitrogen oxide concentration detector according to claim 1, wherein an effective volume of said second gap is 50% or less of an effective volume of said first gap.
直な方向に投影したとき、前記第１空隙部と前記第２空
隙部とが互いに概ね重なり合う位置にあり、前記第１空
隙部と前記第２空隙部の間の固体電解質層を貫通して固
体電解質層に垂直な方向に伸びる前記第２拡散通路によ
って該第１空隙部と該第２空隙部とが連通されている請
求項１〜４のいずれかに記載の窒素酸化物濃度検出器。5. When the nitrogen oxide concentration detector is projected in a direction perpendicular to the solid electrolyte layer, the first gap and the second gap are located at positions substantially overlapping each other, and The first gap and the second gap are communicated by the second diffusion passage extending through the solid electrolyte layer between the second gaps in a direction perpendicular to the solid electrolyte layer. A nitrogen oxide concentration detector according to any one of claims 1 to 4.
いる請求項１〜５のいずれかに記載の窒素酸化物濃度検
出器。6. The nitrogen oxide concentration detector according to claim 1, wherein said second void portion is filled with a porous material.
隙部側に設けた多孔質の電極が白金、ロジウム、パラジ
ウム、イリジウム、レニウムから選ばれるいずれかの金
属又はその合金からなり、他の電極が白金又は白金合金
からなる請求項１〜６のいずれかに記載の窒素酸化物濃
度検出器。7. A porous electrode provided on the second gap side of the second oxygen pumping cell is made of any metal selected from platinum, rhodium, palladium, iridium and rhenium or an alloy thereof, and The nitrogen oxide concentration detector according to any one of claims 1 to 6, wherein the electrode is made of platinum or a platinum alloy.
白金、ロジウム、パラジウム、イリジウム、レニウムか
ら選ばれるいずれかの金属又はその合金からなる請求項
１〜７のいずれかに記載の窒素酸化物濃度検出器。8. A porous electrode provided in the first void portion,
The nitrogen oxide concentration detector according to any one of claims 1 to 7, comprising a metal selected from platinum, rhodium, palladium, iridium, and rhenium or an alloy thereof.
白金、ロジウム、パラジウム、イリジウム、レニウムか
ら選ばれるいずれかの金属又はその合金と、Ａｇ，Ａ
ｕ，Ｎｉ，Ｃｏ，Ｃｒ，Ｆｅ，Ｍｎ，Ｃｕ，Ｔｉ，Ａ
ｌ，Ｐｂ，Ｚｎ，Ｓｎ，Ｉｎから選ばれる少なくとも１
種とを含有する請求項１〜７のいずれかに記載の窒素酸
化物濃度検出器。9. A porous electrode provided in the first void portion,
A metal selected from platinum, rhodium, palladium, iridium, and rhenium or an alloy thereof, and Ag, A
u, Ni, Co, Cr, Fe, Mn, Cu, Ti, A
at least one selected from l, Pb, Zn, Sn, In
The nitrogen oxide concentration detector according to any one of claims 1 to 7, further comprising a seed.
を有する加熱ヒータを設けた層が積層され、窒素酸化物
濃度検出器を固体電解質層に垂直な方向に投影したとき
前記第１空隙部、前記第２空隙部及び前記面状の発熱部
が互いに概ね重なり合う位置にある請求項５に記載の窒
素酸化物濃度検出器。10. A layer provided with a heater having a planar heating portion is laminated on the laminated solid electrolyte layer, and the first layer is formed by projecting a nitrogen oxide concentration detector in a direction perpendicular to the solid electrolyte layer. The nitrogen oxide concentration detector according to claim 5, wherein the gap, the second gap, and the planar heat generating portion are located at positions substantially overlapping each other.
積層された固体電解質層を挟むように配設されている請
求項１０に記載の窒素酸化物濃度検出器。11. A plurality of layers provided with the heater,
The nitrogen oxide concentration detector according to claim 10, wherein the detector is arranged so as to sandwich the stacked solid electrolyte layers.
層との間に、前記第１空隙部及び前記第２空隙部の少な
くとも一方から抜き取られた酸素を排出するための排気
路が設けられている請求項１０に記載の窒素酸化物濃度
検出器。12. An exhaust passage for exhausting oxygen extracted from at least one of the first gap and the second gap is provided between the layer provided with the heater and the solid electrolyte layer. The nitrogen oxide concentration detector according to claim 10, wherein:
と白金又は白金合金の複合材料からなり、前記加熱ヒー
タのリード部が白金又は白金合金からなり、前記加熱ヒ
ータのリード部の常温抵抗値が該加熱ヒータ全体の常温
抵抗値の３０％以下である請求項１０〜１２のいずれか
に記載の窒素酸化物濃度検出器。13. A heating part of the heater is made of a composite material of ceramics and platinum or a platinum alloy. A lead part of the heater is made of platinum or a platinum alloy. The nitrogen oxide concentration detector according to any one of claims 10 to 12, which is 30% or less of the normal temperature resistance value of the entire heater.
を備えた第１酸素ポンピングセル及び酸素濃度測定セル
を有する第１空隙部と、固体電解質層に一対の多孔質電
極を備えた第２酸素ポンピングセルを有する第２空隙部
と、前記第１空隙部を被測定ガス側と連通する第１拡散
通路と、前記第１空隙部を第２空隙部に連通する第２拡
散通路とを備える固体電解質層が積層されてなるととも
に、前記第１酸素ポンピングセル、前記酸素濃度測定セ
ル及び前記第２酸素ポンピングセルがいずれも異なる固
体電解質層に設けられている窒素酸化物濃度検出器を用
意すること、（ｂ）前記第１拡散通路を通して前記第１
空隙部に導入した被測定ガスから窒素酸化物が実質的に
分解しない所定の低酸素濃度まで、前記酸素濃度測定セ
ルで酸素濃度を測定しつつ前記第１酸素ポンピングセル
によって該第１空隙部から酸素を抜き取ること、（ｃ）
所定の低酸素濃度とした被測定ガスを前記第２拡散通路
を通して前記第２空隙部に導入すること、（ｄ）前記第
２空隙部に設けられた前記第２酸素ポンピングセルに所
定電圧を印加して該第２空隙部内の被測定ガス中の窒素
酸化物を分解しつつ酸素を抜き取ること、（ｅ）このと
き前記第２酸素ポンピングセルに流れるポンプ電流Ｉｐ
2に基いて被測定ガス中の窒素酸化物濃度を検出するこ
と、を特徴とする窒素酸化物濃度の検出方法。14. (a) A first oxygen pumping cell having a solid electrolyte layer and a pair of porous electrodes, a first void having an oxygen concentration measuring cell, and a solid electrolyte layer having a pair of porous electrodes. A second cavity having a second oxygen pumping cell, a first diffusion passage communicating the first cavity with the gas to be measured, and a second diffusion passage communicating the first cavity with the second cavity. And a nitrogen oxide concentration detector in which the first oxygen pumping cell, the oxygen concentration measurement cell, and the second oxygen pumping cell are all provided in different solid electrolyte layers. Providing (b) the first diffusion passage through the first diffusion passage;
From the gas to be measured introduced into the cavity to a predetermined low oxygen concentration at which nitrogen oxides are not substantially decomposed, the oxygen concentration is measured by the first oxygen pumping cell while the oxygen concentration is measured by the oxygen concentration measuring cell. Withdrawing oxygen, (c)
Introducing a gas to be measured having a predetermined low oxygen concentration into the second gap through the second diffusion passage; (d) applying a predetermined voltage to the second oxygen pumping cell provided in the second gap And extracting oxygen while decomposing nitrogen oxides in the gas to be measured in the second gap, (e) a pump current Ip flowing through the second oxygen pumping cell at this time.
2. A nitrogen oxide concentration detection method, comprising: detecting a nitrogen oxide concentration in a gas to be measured based on 2 .
度の検出値に及ぼす影響を、あらかじめ酸素の濃度と窒
素酸化物の濃度が異なり、かつ既知である標準ガスを用
いて測定したデータに基いて補正する請求項１４に記載
の窒素酸化物濃度の検出方法。15. The effect of the oxygen concentration in the gas to be measured on the detected value of the nitrogen oxide concentration is measured by using a known standard gas in which the concentration of oxygen and the concentration of nitrogen oxide are different in advance and are known. The method for detecting a nitrogen oxide concentration according to claim 14, wherein the correction is performed based on:
いて前記酸素濃度測定セルで前記第１空隙部内の酸素濃
度を監視しつつ前記第１酸素ポンピングセルで該第１空
隙部内の酸素濃度を窒素酸化物が実質的に分解されない
低濃度に保つときの被測定ガス中の酸素濃度と該第１酸
素ポンピングセルのポンプ電流Ｉｐ1との関係、（２）
窒素酸化物濃度がゼロのときのＯ2濃度と前記第２空隙
部から酸素を抜き取る前記第２酸素ポンピングセルのポ
ンプ電流Ｉｐ2oとの関係、及び（３）測定対象とする被
測定ガスと同レベルの酸素濃度を有し、異なる窒素酸化
物濃度を有する標準ガスについて求めた窒素酸化物濃度
と前記第２酸素ポンピングセルのポンプ電流Ｉｐ2との
関係である請求項１５に記載の窒素酸化物濃度の検出方
法。16. The data according to claim 1, wherein: (1) the oxygen concentration in the first gap is monitored by the first oxygen pumping cell while monitoring the oxygen concentration in the first gap using the standard gas. the relationship between the pump current Ip 1 of the oxygen concentration and the first oxygen pumping cell in a measurement gas when keeping the concentration low concentration of nitrogen oxides is not substantially degraded, (2)
The relationship between the O 2 concentration when the nitrogen oxide concentration is zero and the pump current Ip 2 o of the second oxygen pumping cell for extracting oxygen from the second gap, and (3) the measured gas to be measured It has an oxygen concentration of the same level, different concentration of nitrogen oxides NOx according to claim 15 which is a relationship between the nitrogen oxide concentration determined for the standard gas and pumping currents Ip 2 of the second oxygen pumping cell having a How to detect substance concentration.
窒素酸化物濃度とポンプ電流Ｉｐ2の間に所定の函数関
係があると仮定し、あらかじめマイクロコンピュータの
メモリーに蓄積した前記データに基きマイクロコンピュ
ータで演算して補正した窒素酸化物濃度を求める請求項
１５に記載の窒素酸化物濃度の検出方法。17. Even if the oxygen concentration in the gas to be measured changes,
Assuming a predetermined function relationship between the NOx concentration and the pump current Ip 2, claim to obtain the NOx concentration corrected by calculating a microcomputer based on the data stored in advance in the microcomputer memory 15. The method for detecting a nitrogen oxide concentration according to 15.
２拡散通路の開口が形成された前記固体電解質層の層面
であって前記第１空隙部を区画する壁面に部分的に、か
つ前記第２拡散通路の近傍に設けられたことを特徴とす
る請求項１〜１３のいずれかに記載の窒素酸化物濃度検
出器。18. An electrode of the oxygen concentration measuring cell, wherein the electrode is partially formed on a wall surface of the solid electrolyte layer in which an opening of the second diffusion passage is formed and which partitions the first void, and 14. The nitrogen oxide concentration detector according to claim 1, wherein the detector is provided in the vicinity of the second diffusion passage.
測定セルの電極が、前記第１拡散通路から離間されて前
記第２拡散通路の近傍に設けられたことを特徴とする請
求項１〜１３のいずれかに記載の窒素酸化物濃度検出
器。19. The apparatus according to claim 1, wherein an electrode of the oxygen concentration measuring cell at least on the first void side is provided in the vicinity of the second diffusion passage so as to be separated from the first diffusion passage. 14. The nitrogen oxide concentration detector according to any one of 13.
１空隙部側の酸素濃度測定セルの電極と前記第１拡散通
路の出口との距離が略１．５ｍｍ以上であることを特徴
とする請求項１８又は１９に記載の窒素酸化物濃度検出
器。20. The distance between at least the electrode of the oxygen concentration measuring cell on the first void side and the outlet of the first diffusion passage on the same plane is at least about 1.5 mm. 20. The nitrogen oxide concentration detector according to 18 or 19.
一対の多孔質電極が固体電解質層を挟んでその両側に配
されることを特徴とする請求項１〜１３及び１８〜２０
の一に記載の窒素酸化物濃度検出器。21. A pair of porous electrodes of said first and second oxygen pumping cells are disposed on both sides of a solid electrolyte layer.
2. The nitrogen oxide concentration detector according to claim 1.
らなることを特徴とする請求項１〜１３及び１８〜２１
の一に記載の窒素酸化物濃度検出器。22. The solid electrolyte layer according to claim 1, wherein said solid electrolyte layer is made of sheet zirconia.
2. The nitrogen oxide concentration detector according to claim 1.
ルが挟持される固体電解質層を貫通して配設され、前記
第２酸素ポンピングセルが前記酸素濃度測定セルの固体
電解質層に隣接する固体電解質層を挟んで配設されるこ
とを特徴とする請求項１〜１３及び１８〜２２の一に記
載の窒素酸化物濃度検出器。23. The second void portion is provided to penetrate a solid electrolyte layer in which the oxygen concentration measurement cell is sandwiched, and the second oxygen pumping cell is adjacent to the solid electrolyte layer of the oxygen concentration measurement cell. The nitrogen oxide concentration detector according to any one of claims 1 to 13, and 18 to 22, wherein the nitrogen oxide concentration detector is provided with a solid electrolyte layer interposed therebetween.
ベルにまで延在し、前記第２拡散通路が前記層レベルに
おいて第１、第２空隙部の間に介在することを特徴とす
る請求項２３に記載の窒素酸化物濃度検出器。24. The semiconductor device according to claim 24, wherein the second gap extends to a layer level of the first gap, and the second diffusion passage is interposed between the first and second gaps at the layer level. The nitrogen oxide concentration detector according to claim 23, wherein:
が外気に連通する通路に露出することを特徴とする請求
項２３又は２４に記載の窒素酸化物濃度検出器。25. The nitrogen oxide concentration detector according to claim 23, wherein the outer electrode of the second oxygen pumping cell is exposed to a passage communicating with the outside air.
ピングセルの固体電解質層を横切って延びる通路部分を
介して、前記通路に露出することを特徴とする請求項２
５に記載の窒素酸化物濃度検出器。26. The oxygen concentration measuring cell is exposed to the passage through a passage portion extending across the solid electrolyte layer of the second oxygen pumping cell.
6. The nitrogen oxide concentration detector according to 5.
ルにまで延在し、かつ該第２空隙部に充填された多孔質
材料が第２拡散通路を成すことを特徴とする請求項２３
に記載の窒素酸化物濃度検出器。27. The method according to claim 27, wherein the second gap extends to a layer level of the first gap, and the porous material filled in the second gap forms a second diffusion passage. Claim 23
2. The nitrogen oxide concentration detector according to 1.
くとも一側面に開口することを特徴とする請求項１〜１
３及び１８〜２７の一に記載の窒素酸化物濃度検出器。28. The detector according to claim 1, wherein the first diffusion passage is opened on at least one side surface of the detector body.
28. The nitrogen oxide concentration detector according to any one of 3 and 18 to 27.
の外部に連通する通路を残して第１及び第２酸素ポンピ
ングセルの少なくとも一方の外側多孔質電極を覆って配
設されたことを特徴とする請求項１〜１３及び１８〜２
８の一に記載の窒素酸化物濃度検出器。29. At least one heater is disposed over at least one outer porous electrode of the first and second oxygen pumping cells, leaving a passage communicating with the outside of the detector. Claims 1 to 13 and 18 to 2
8. The nitrogen oxide concentration detector according to item 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15919597A JP3587282B2 (en) | 1996-05-31 | 1997-06-02 | Nitrogen oxide concentration detector |
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16081296 | 1996-05-31 | ||
| JP8-160812 | 1996-12-03 | ||
| JP33748396 | 1996-12-03 | ||
| JP8-337483 | 1996-12-03 | ||
| JP15919597A JP3587282B2 (en) | 1996-05-31 | 1997-06-02 | Nitrogen oxide concentration detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10221298A true JPH10221298A (en) | 1998-08-21 |
| JP3587282B2 JP3587282B2 (en) | 2004-11-10 |
Family
ID=27321499
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15919597A Expired - Lifetime JP3587282B2 (en) | 1996-05-31 | 1997-06-02 | Nitrogen oxide concentration detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3587282B2 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003515166A (en) * | 1999-11-25 | 2003-04-22 | シーメンス アクチエンゲゼルシヤフト | Method for determining NOx concentration |
| JP2004028766A (en) * | 2002-06-25 | 2004-01-29 | Ngk Spark Plug Co Ltd | Gas sensor manufacturing method, and gas sensor |
| US6743352B2 (en) | 1997-03-21 | 2004-06-01 | Ngk Spark Plug Co., Ltd. | Method and apparatus for correcting a gas sensor response for moisture in exhaust gas |
| JP2010066246A (en) * | 2008-09-15 | 2010-03-25 | Nippon Soken Inc | Method of manufacturing gas sensor element |
| JP2010249801A (en) * | 2009-03-27 | 2010-11-04 | Ngk Spark Plug Co Ltd | Gas sensor |
| JP2015200642A (en) * | 2014-03-31 | 2015-11-12 | 日本碍子株式会社 | Sensor element and gas sensor |
| JP2016125891A (en) * | 2014-12-26 | 2016-07-11 | 日本特殊陶業株式会社 | Gas sensor element and gas sensor |
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-
1997
- 1997-06-02 JP JP15919597A patent/JP3587282B2/en not_active Expired - Lifetime
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6743352B2 (en) | 1997-03-21 | 2004-06-01 | Ngk Spark Plug Co., Ltd. | Method and apparatus for correcting a gas sensor response for moisture in exhaust gas |
| US6923902B2 (en) | 1997-03-21 | 2005-08-02 | Ngk Spark Plug Co, Ltd. | Methods and apparatus for measuring NOx gas concentration, for detecting exhaust gas concentration and for calibrating and controlling gas sensor |
| JP2003515166A (en) * | 1999-11-25 | 2003-04-22 | シーメンス アクチエンゲゼルシヤフト | Method for determining NOx concentration |
| JP4746239B2 (en) * | 1999-11-25 | 2011-08-10 | シーメンス アクチエンゲゼルシヤフト | Method for obtaining NOx concentration |
| JP2004028766A (en) * | 2002-06-25 | 2004-01-29 | Ngk Spark Plug Co Ltd | Gas sensor manufacturing method, and gas sensor |
| JP2010066246A (en) * | 2008-09-15 | 2010-03-25 | Nippon Soken Inc | Method of manufacturing gas sensor element |
| JP2010249801A (en) * | 2009-03-27 | 2010-11-04 | Ngk Spark Plug Co Ltd | Gas sensor |
| JP2015200642A (en) * | 2014-03-31 | 2015-11-12 | 日本碍子株式会社 | Sensor element and gas sensor |
| JP2016125891A (en) * | 2014-12-26 | 2016-07-11 | 日本特殊陶業株式会社 | Gas sensor element and gas sensor |
| JP2017207467A (en) * | 2016-05-17 | 2017-11-24 | 日本特殊陶業株式会社 | Gas sensor element |
| CN113466308A (en) * | 2020-03-31 | 2021-10-01 | 日本碍子株式会社 | Gas sensor |
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| Publication number | Publication date |
|---|---|
| JP3587282B2 (en) | 2004-11-10 |
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