JP2001041927A - Nitrogen oxide gas sensor - Google Patents
Nitrogen oxide gas sensorInfo
- Publication number
- JP2001041927A JP2001041927A JP11217789A JP21778999A JP2001041927A JP 2001041927 A JP2001041927 A JP 2001041927A JP 11217789 A JP11217789 A JP 11217789A JP 21778999 A JP21778999 A JP 21778999A JP 2001041927 A JP2001041927 A JP 2001041927A
- Authority
- JP
- Japan
- Prior art keywords
- gas
- electrode
- oxygen
- nox
- detection chamber
- 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.)
- Withdrawn
Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ガスセンサ、特に
内燃機関の排気ガス等の測定ガス雰囲気中に含まれる総
ＮＯx濃度をリアルタイムに検知できる窒素酸化物ガス
センサに属する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas sensor, and more particularly to a nitrogen oxide gas sensor capable of detecting in real time the total NOx concentration contained in a measurement gas atmosphere such as an exhaust gas of an internal combustion engine.
【０００２】[0002]
【従来の技術】近年、内燃機関の排ガス中に含まれる総
ＮＯx濃度を直接測定できる簡便な全固体素子型ＮＯxセ
ンサがいくつか提案されている。本発明者等は、酸素イ
オン伝導体であるジルコニア固体電解質を用いた高温作
動型の混成電位式ＮＯxセンサを既に提案している。例
えば、特開平９−２７４０１１号公報は、窒素酸化物の
検出に際し非測定ガスによる干渉を回避して総ＮＯx濃
度を検知できる窒素酸化物検出装置を開示する。この窒
素酸化物検出装置では、酸素イオン伝導体であるジルコ
ニア固体電解質によりガス検知室を形成し、固体電解質
体上の電極間に電圧を印加して電気化学的な酸素ポンピ
ング作用を発生し、酸素をガス検知室に導入することに
より、測定ガス中のＨＣ、ＣＯ及びＮＯを酸化させる。
ＨＣ、ＣＯは無害なＨ2ＯとＣＯ2に変換され、ＮＯはＮ
Ｏ2に単一ガス化変換され総ＮＯxとして混成電位型ＮＯ
xセンサ部で検知される。2. Description of the Related Art In recent years, several simple all-solid-element NOx sensors capable of directly measuring the total NOx concentration contained in exhaust gas of an internal combustion engine have been proposed. The present inventors have already proposed a high-temperature operation type mixed potential NOx sensor using a zirconia solid electrolyte which is an oxygen ion conductor. For example, Japanese Patent Application Laid-Open No. 9-274011 discloses a nitrogen oxide detection device capable of detecting the total NOx concentration while avoiding interference by a non-measurement gas when detecting nitrogen oxide. In this nitrogen oxide detection device, a gas detection chamber is formed by a zirconia solid electrolyte, which is an oxygen ion conductor, and a voltage is applied between electrodes on the solid electrolyte body to generate an electrochemical oxygen pumping action, whereby oxygen Is introduced into the gas detection chamber to oxidize HC, CO and NO in the measurement gas.
HC and CO are converted to harmless H 2 O and CO 2 , NO is N
Mixed potential NO as single gas converted to O 2 and converted to total NOx
It is detected by the x sensor unit.
【０００３】図１５に示すように、特開平９−２７４０
１１号公報に示される窒素酸化物検知装置(30)は、固体
電解質(31)と、固体電解質(31)の表面側に沿って形成さ
れかつ一定の酸素雰囲気を有する大気に通ずるダクト(3
2)と、固体電解質(31)の裏面側に形成された検知室(33)
と、固体電解質(31)の表面及び裏面に取り付けられた一
対の電気化学的酸素ポンプ(34, 35)と、検知室(33)内に
設置されたＮＯx検知電極(36)及びＮＯx参照極(37)とで
構成される。電気化学的酸素ポンプ(34, 35)はリード線
(20, 21)により直流電源(23)に接続され、ＮＯx検知電
極(36)とＮＯx参照極(37)はリード線(22, 22a)により電
位差計(24)に接続される。ＮＯx検知電極(36)とＮＯx参
照極(37)との間の電位差を電位差計(24)により測定して
ＮＯxの量を検出することができる。[0003] As shown in FIG.
The nitrogen oxide detection device (30) disclosed in Japanese Patent Publication No. 11-301 is composed of a solid electrolyte (31) and a duct (3) formed along the surface side of the solid electrolyte (31) and communicating with the atmosphere having a constant oxygen atmosphere.
2) and a detection chamber (33) formed on the back side of the solid electrolyte (31)
And a pair of electrochemical oxygen pumps (34, 35) attached to the front and back surfaces of the solid electrolyte (31), and a NOx detection electrode (36) and a NOx reference electrode ( 37). Electrochemical oxygen pump (34, 35) leads
The NOx detection electrode (36) and the NOx reference electrode (37) are connected to the potentiometer (24) by the lead wires (22, 22a). The amount of NOx can be detected by measuring the potential difference between the NOx detection electrode (36) and the NOx reference electrode (37) with a potentiometer (24).
【０００４】また、特開平１１−２３５２６号公報は、
酸素及びＮＯxに活性な酸素ポンプ（ＮＯx変換ポンプ）
をジルコニア固体電解質内のガス検知室に別途設け、検
知対象雰囲気中のＮＯをＮＯ2に変換し、窒素酸化物ガ
ス濃度を検知する窒素酸化物センサを示す。[0004] Also, Japanese Patent Application Laid-Open No. 11-23526 discloses that
Oxygen pump active for oxygen and NOx (NOx conversion pump)
Is separately provided in a gas detection chamber in a zirconia solid electrolyte, and converts a NO in an atmosphere to be detected into NO 2 to detect a nitrogen oxide gas concentration.
【０００５】[0005]
【発明が解決しようとする課題】このように、従来提案
されている総ＮＯx検知システムには、下記の構造が必
要であった。 （ａ） センサ検知室内の酸素濃度を制御して排ガス中
のＨＣ、ＣＯ等の還元性ガスを酸化無害化する酸素ポン
プ電極 （ｂ） センサ検知室内の酸素濃度を測定する酸素セン
サ （ｃ） センサ検知室内で測定ガス中のＮＯxをＮＯ2又
はＮＯの単一組成ガスに変換するＮＯx変換電極 （ｄ） 変換されたＮＯxガス濃度を検知するＮＯx検知
電極 （ｅ） センサ作動温度をフィードバック制御する温度
センサ（印刷型熱電対） （ｆ） センサを高温作動させるヒータAs described above, the total NOx detection system proposed conventionally requires the following structure. (A) an oxygen pump electrode that controls the oxygen concentration in the sensor detection chamber to oxidize and detoxify reducing gases such as HC and CO in exhaust gas. (B) an oxygen sensor that measures the oxygen concentration in the sensor detection chamber. (C) sensor temperature feedback control of the single composition into a gas NOx conversion electrode (d) NOx detection electrodes for detecting the converted NOx gas concentration was (e) sensor operating temperature of the NOx in the measurement gas in the detection chamber NO 2 or NO Sensor (printed thermocouple) (f) Heater that operates the sensor at high temperature
【０００６】特開平９−２７４０１１号公報では、
（ａ）と（ｃ）が兼用され、（ｂ）も基本的になくても
かまわない。更に、温度センサとして酸素ポンプ電極を
用いて固体電解質のインピーダンスを測定する方法も適
用できる。これらを考慮すれば、一対の酸素ポンプ、Ｎ
Ｏx検知センサ、ヒータが不可欠であり、センサに接続
されるリード線の本数は、最小６本必要となる。ＮＯx
の高効率な単一ガス化を行うために構成を増やせばその
分リード線が増加することになる。In Japanese Patent Application Laid-Open No. 9-274011,
(A) and (c) are shared, and (b) may be basically omitted. Further, a method of measuring the impedance of the solid electrolyte using an oxygen pump electrode as a temperature sensor is also applicable. Considering these, a pair of oxygen pumps, N
An Ox detection sensor and a heater are indispensable, and the minimum number of lead wires connected to the sensor is six. NOx
If the configuration is increased to perform highly efficient single gasification, the number of lead wires will increase accordingly.
【０００７】一方、近年自動車エンジンの燃費規制と排
ガス規制の大幅な強化に対応できる将来的に最も期待さ
れるエンジンシステムとして、ガソリンの直噴システム
に代表される超希薄燃焼システムが実用化されている。
しかしながら、現状のガソリンエンジンでは酸素過剰雰
囲気で直接ＮＯxを分解浄化できる触媒はない。そのた
め、実用化されたシステムでは周期的にリッチ領域に戻
しそこで増大する排ガス中のＨＣをＮＯx還元剤として
用いＮＯxを分解浄化している。ところが、直噴システ
ムには通常ＨＣを浄化する三元触媒も設けられ、ＯＢＤ
規制に対応するためＨＣ浄化機能の監視が必要である。
よって、三元触媒の酸素吸蔵を監視する目的で触媒の上
流と下流にそれぞれ酸素センサ（λ−Ｏ2センサ）が設
置される。触媒浄化システムには、ＮＯx検知機能と酸
素検知機能の２種類が一体化されたガス濃度検知装置が
望ましいが、センサ構成にλ−Ｏ2センサ用リード線が
更に増えるため、センサの構造及び制御システムが複雑
になる欠点がある。従って、従来の総ＮＯx検知センサ
では、その構成上、センサ製造上又はセンサ駆動制御シ
ステムにおいて更なるセンサ構成の簡素化、特にリード
線本数の低減が必要であり、よってセンサ制御の簡易化
が望まれている。On the other hand, in recent years, an ultra-lean combustion system represented by a direct injection system of gasoline has been put to practical use as an engine system most expected in the future that can cope with the drastic strengthening of fuel efficiency regulations and exhaust gas regulations of automobile engines. I have.
However, in the current gasoline engine, there is no catalyst capable of directly decomposing and purifying NOx in an oxygen-excess atmosphere. Therefore, in a practical system, NOx is decomposed and purified by periodically returning to a rich region and using HC in the exhaust gas which increases there as a NOx reducing agent. However, the direct injection system is usually provided with a three-way catalyst for purifying HC, and the OBD
It is necessary to monitor the HC purification function in order to comply with regulations.
Therefore, oxygen sensors (λ-O 2 sensors) are provided upstream and downstream of the three-way catalyst for the purpose of monitoring oxygen storage. For the catalyst purification system, it is desirable to use a gas concentration detection device that integrates two types of NOx detection function and oxygen detection function. However, since the number of lead wires for the λ-O 2 sensor further increases in the sensor configuration, the structure and control of the sensor There is a disadvantage that the system becomes complicated. Therefore, in the conventional total NOx detection sensor, it is necessary to further simplify the sensor configuration in the sensor production or the sensor drive control system, particularly, to reduce the number of lead wires because of its configuration. It is rare.
【０００８】そこで、本発明は、センサ機能及び検知精
度を低下せずに、電極数、リード線数を大幅に減少する
ことができ、簡素化された構造を有する窒素酸化物ガス
センサを提供することを目的とする。Accordingly, the present invention is to provide a nitrogen oxide gas sensor having a simplified structure in which the number of electrodes and the number of leads can be significantly reduced without lowering the sensor function and detection accuracy. With the goal.
【０００９】[0009]
【課題を解決するための手段】本発明による窒素酸化物
ガスセンサは、酸素イオン伝導性を有する固体電解質に
より形成された酸素イオン透過層(2)と、測定ガス雰囲
気に通ずるガス導入口(13)が設けられたガス検知室(6)
と、酸素イオン透過層(2)と同一のイオン伝導体により
連続しているガス検知室(6)内の底壁(10)と、酸素イオ
ン透過層(2)を介してガス検知室(6)の反対側に形成され
かつ大気に通じるダクト(5)と、ダクト(5)内で酸素イオ
ン透過層(2)に形成された酸素に活性な外側電極(7)と、
ガス検知室(6)内で酸素イオン透過層(2)に形成されかつ
酸素とＮＯxに活性な内側電極(8)と、内側電極(8)と対
面してガス検知室(6)内の底壁(10)に設置されかつ酸素
及びＮＯxに対して活性な検知電極(9)とを備えている。
カソード電極である外側電極(7)及びアノード電極であ
る内側電極(8)間に電圧を印加して、酸素イオン透過層
(2)を介してダクト(5)からガス検知室(6)内に供給され
る酸素により測定ガス中に含まれるＮＯxガス中のＮＯ
を酸化させてＮＯ2の単一ガスとし又はガス検知室(6)内
の還元性ガスを酸化させる。また、検知電極(9)と外側
電極(7)との間に生じる電位差を測定して、測定ガス中
の総ＮＯx濃度を検知する。A nitrogen oxide gas sensor according to the present invention comprises an oxygen ion permeable layer (2) formed of a solid electrolyte having oxygen ion conductivity, and a gas inlet (13) communicating with a measurement gas atmosphere. Gas detection room equipped with (6)
And the bottom wall (10) in the gas detection chamber (6), which is continuous with the oxygen ion permeable layer (2) by the same ion conductor, and the gas detection chamber (6) through the oxygen ion permeable layer (2). A) a duct (5) formed on the opposite side to the atmosphere and communicating with the atmosphere, and an oxygen-active outer electrode (7) formed in the oxygen ion permeable layer (2) in the duct (5).
An inner electrode (8) formed in the oxygen ion permeable layer (2) in the gas detection chamber (6) and active on oxygen and NOx, and a bottom in the gas detection chamber (6) facing the inner electrode (8). A sensing electrode (9) is provided on the wall (10) and is active against oxygen and NOx.
A voltage is applied between the outer electrode (7), which is a cathode electrode, and the inner electrode (8), which is an anode electrode, to form an oxygen ion permeable layer.
Oxygen supplied into the gas detection chamber (6) from the duct (5) through (2) causes NO in NOx gas contained in the measurement gas to be measured.
Is oxidized into a single gas of NO 2 or the reducing gas in the gas detection chamber (6) is oxidized. Further, a potential difference between the detection electrode (9) and the outer electrode (7) is measured to detect the total NOx concentration in the measurement gas.
【００１０】カソード電極としての外側電極(7)とアノ
ード電極としての内側電極(8)との間に外部電源により
定電圧を印加し、外側電極(7)と内側電極(8)を用いて電
気化学的に酸素のポンピングを行う。大気にのみ通ずる
酸素に活性な外側電極(7)は、通常ＮＯxに対する感度が
ないため、酸素とＮＯxに活性を有し混成電位に起因す
る電位差を発生する検知電極(9)に対し参照極として機
能し、その間の化学ポテンシャル差（電位差）は、ＮＯ
xの感度に対応する出力となる。外側電極(7)はＮＯx基
準極でもあるため、外側電極(7)が曝されるダクト(5)内
の酸素濃度は一定であることが望ましく、大気に通じて
いる。外側電極(7)、内側電極(8)により酸素のポンピン
グを行うと同時に測定ガス中の総ＮＯx濃度を検知電極
(9)と外側電極(7)を用いて検知することができる。[0010] A constant voltage is applied between an outer electrode (7) as a cathode electrode and an inner electrode (8) as an anode electrode by an external power source, and electric power is applied using the outer electrode (7) and the inner electrode (8). Chemical oxygen pumping. Since the outer electrode (7), which is active only for oxygen that passes only to the atmosphere, is generally insensitive to NOx, it serves as a reference electrode for the detection electrode (9), which is active in oxygen and NOx and generates a potential difference caused by a mixed potential. Function and the chemical potential difference (potential difference) between them is NO
The output corresponds to the sensitivity of x. Since the outer electrode (7) is also a NOx reference electrode, it is desirable that the oxygen concentration in the duct (5) to which the outer electrode (7) is exposed is constant, leading to the atmosphere. The outer electrode (7) and the inner electrode (8) pump oxygen and simultaneously detect the total NOx concentration in the measurement gas.
Detection can be performed using (9) and the outer electrode (7).
【００１１】本発明の実施の形態では、外側電極(7)と
内側電極(8)との間で一定の電流を流して、測定ガス中
の総ＮＯx濃度を検知することもできる。ガス導入口(1
3)は、測定ガス中の酸素濃度が０%であっても、ガス検
知室(6)内の酸素濃度を０.１vol%以上に維持するガス拡
散抵抗を有する。ガス検知室(6)の内部に配置した多孔
質体(6a)により、ガス検知室(6)内の酸素濃度を０.１vo
l%以上に維持してもよい。酸素とＮＯxに活性な内側電
極(8)の面のうち、少なくとも検知電極(9)と直接対向す
る面はＮＯxに対して活性であり、検知電極(9)と直接対
向しない面はＮＯxに対して不活性としてもよい。ガス
検知室(6)内の酸素濃度は一定に保持され易く、測定ガ
ス中の酸素濃度変動に対してより安定したＮＯx出力を
得ることができる。In the embodiment of the present invention, it is possible to detect a total NOx concentration in the measurement gas by flowing a constant current between the outer electrode (7) and the inner electrode (8). Gas inlet (1
3) has a gas diffusion resistance that maintains the oxygen concentration in the gas detection chamber (6) at 0.1 vol% or more even if the oxygen concentration in the measurement gas is 0%. The oxygen concentration in the gas detection chamber (6) is reduced to 0.1 vo by the porous body (6a) disposed inside the gas detection chamber (6).
It may be maintained at l% or more. Of the surfaces of the inner electrode (8) that are active on oxygen and NOx, at least the surface directly facing the detection electrode (9) is active on NOx, and the surface not directly facing the detection electrode (9) is on NOx. May be inactive. The oxygen concentration in the gas detection chamber (6) is easily kept constant, and a more stable NOx output can be obtained with respect to the oxygen concentration fluctuation in the measurement gas.
【００１２】ガス検知室(6)の酸素イオン透過層(2)の内
側電極設置面面積に対する内側電極(8)の占有比率は４
０%以上でありかつ内側電極(8)に対向する検知電極(9)
の面積は内側電極(8)の面積より小さく、内側電極(8)を
設置したガス検知室(6)内でガス導入口(13)側から測定
ガスの侵入方向の後方部に検知電極(9)を配置すると、
更に高効率で安定した総ＮＯx濃度を検知することがで
きる。The occupation ratio of the inner electrode (8) to the area of the inner electrode installation surface of the oxygen ion permeable layer (2) in the gas detection chamber (6) is 4
The sensing electrode (9) which is 0% or more and faces the inner electrode (8)
The area of the inner electrode (8) is smaller than the area of the inner electrode (8) .In the gas detection chamber (6) where the inner electrode (8) is installed, the detection electrode (9 )
Further, a highly efficient and stable total NOx concentration can be detected.
【００１３】内側電極(8)を設置したガス検知室(6)内で
ガス導入口(13)側から測定ガスの侵入方向の後方部に検
知電極(9)が配置される。測定ガス雰囲気に通じるガス
導入口(13)とそれに連絡するガス検知室(6)との間にガ
ス拡散抵抗を制御する内部ガス通路又は内部ガス空間を
形成してもよい。ガス導入口(13)と検知電極(9)の設置
されているガス検知室(6)との間に内部空間又は内部ガ
ス通路を形成し、内部空間とガス検知室(6)との間又は
内部ガス通路にガス拡散抵抗を設けることにより更に安
定して総ＮＯx濃度検知を行うことができる。内部ガス
通路、内部ガス空間又はガス検知室(6)のいずれかに酸
化触媒層、酸化触媒体又は酸化触媒担持体を配置すれ
ば、それにより測定ガス中のＨＣ等の還元性ガスは完全
に酸化される。In the gas detection chamber (6) in which the inner electrode (8) is installed, a detection electrode (9) is arranged from the side of the gas inlet (13) in the direction in which the measurement gas enters. An internal gas passage or an internal gas space for controlling gas diffusion resistance may be formed between the gas inlet (13) leading to the measurement gas atmosphere and the gas detection chamber (6) connected to the gas inlet (13). An internal space or an internal gas passage is formed between the gas inlet (13) and the gas detection chamber (6) where the detection electrode (9) is installed, and between the internal space and the gas detection chamber (6) or By providing the gas diffusion resistance in the internal gas passage, the total NOx concentration can be detected more stably. If the oxidation catalyst layer, the oxidation catalyst, or the oxidation catalyst carrier is disposed in any of the internal gas passage, the internal gas space, and the gas detection chamber (6), the reducing gas such as HC in the measurement gas can be completely eliminated. Oxidized.
【００１４】検知電極(9)が、ＮｉＣｒ2Ｏ4、ＭｇＣｒ2
Ｏ4、ＦｅＣｒ2Ｏ4、Ｃｒ2Ｏ3から選択されたクロム酸
化物を主成分とした材料又はＰｔ−Ｒｈ合金、Ｉｒ−Ｒ
ｈ合金、ＰｔとＲｈ酸化物との混相からなる電極であ
り、内側電極(8)のＮＯxに活性な面が、Ｐｔ−Ｒｈ合
金、Ｉｒ−Ｒｈ合金、Ｐｔ−Ｒｕ合金の少なくとも一つ
を主成分とする層からなるので、本発明では更に高性能
検知が可能である。干渉ガスを酸化無害化する触媒とし
ては、金属酸化物触媒ではＣｏ3Ｏ4、Ｍｎ2Ｏ3、Ｃｒ2
Ｏ3等、貴金属触媒ではＰｔ、Ｐｄ、Ｒｕ、Ａｕ等又は
それらの任意の混合物が用いられる。これらの触媒層に
は電圧を印加する必要がないのでリード線は不要であ
る。The detection electrode (9) is made of NiCr 2 O 4 , MgCr 2
A material mainly composed of chromium oxide selected from O 4 , FeCr 2 O 4 , and Cr 2 O 3, a Pt-Rh alloy, Ir-R
h-alloy, an electrode comprising a mixed phase of Pt and Rh oxide, wherein the surface active on the NOx of the inner electrode (8) mainly comprises at least one of a Pt-Rh alloy, an Ir-Rh alloy, and a Pt-Ru alloy. Since the present invention is composed of layers as components, high-performance detection is possible in the present invention. As a catalyst for oxidizing and detoxifying the interference gas, Co 3 O 4 , Mn 2 O 3 , Cr 2
For a noble metal catalyst such as O 3 , Pt, Pd, Ru, Au or the like or an arbitrary mixture thereof is used. Since no voltage needs to be applied to these catalyst layers, no lead wire is required.
【００１５】測定ガス中の酸素濃度を検知するため、酸
素に活性でＮＯxに不活性な付加電極(14)が、固体電解
質により構成された底壁(10)の表面、即ち測定ガス雰囲
気中に直接曝される底壁(10)の裏面又はガス導入口(13)
に連絡するガス検知室(6)内の底壁(10)の表面に固定さ
れる。ダクト(5)の酸素拡散は律速されず、酸素濃度差
に起因する外側電極(7)と付加電極(14)との間の出力
（起電力）を測定して測定ガス中又はガス検知室内の酸
素濃度を検知する。酸素濃度差に基づき外側電極(7)と
付加電極(14)との間の出力を検出して、検知電極(9)と
外側電極(7)との間に生じる電位差出力を補正し、測定
雰囲気中の総ＮＯx濃度を精度よく検知することができ
る。In order to detect the oxygen concentration in the measurement gas, an additional electrode (14) active on oxygen and inert on NOx is provided on the surface of the bottom wall (10) made of a solid electrolyte, that is, in the atmosphere of the measurement gas. The back of the directly exposed bottom wall (10) or gas inlet (13)
Fixed to the surface of the bottom wall (10) in the gas detection chamber (6). The diffusion of oxygen in the duct (5) is not limited, and the output (electromotive force) between the outer electrode (7) and the additional electrode (14) due to the oxygen concentration difference is measured to measure the output in the measurement gas or gas detection chamber. Detect oxygen concentration. The output between the outer electrode (7) and the additional electrode (14) is detected based on the oxygen concentration difference, and the potential difference output generated between the detection electrode (9) and the outer electrode (7) is corrected, and the measurement atmosphere is measured. It is possible to accurately detect the total NOx concentration therein.
【００１６】酸素に活性でかつＮＯxに不活性な付加電
極(14)が、酸素イオン透過層(2)と同一のイオン伝導体
により連続している底壁(10)の測定ガス雰囲気中に直接
曝される底壁(10)の裏面又はガス導入口(13)に連絡する
ガス検知室(6)内の底壁(10)の表面に固定され、付加電
極(14)と外側電極(7)との間の酸素濃度差に起因する起
電力を測定して測定ガス中又は検知ガス中に酸素濃度を
検知する。An additional electrode (14) which is active on oxygen and inert on NOx is directly connected to the measurement gas atmosphere on the bottom wall (10) which is continuous with the oxygen ion permeable layer (2) by the same ion conductor. The additional electrode (14) and the outer electrode (7) are fixed to the back surface of the exposed bottom wall (10) or the surface of the bottom wall (10) in the gas detection chamber (6) communicating with the gas inlet (13). The oxygen concentration is detected in the measurement gas or the detection gas by measuring the electromotive force caused by the difference in oxygen concentration between.
【００１７】外側電極(7)と内側電極(8)間に電圧を印加
したときに、大気中の酸素が酸素イオン透過層(2)を通
じてダクト(5)からガス検知室(6)に導入される。ダクト
(5)は酸素導入に拡散抵抗を付与して、外側電極(7)と内
側電極(8)間に流れる酸素イオン電流が限界電流を生じ
る拡散律速状態でＮＯx濃度を検知することも有効であ
る。ダクト(5)の断面積を減少し又はダクト長を増大す
ることにより拡散律速状態を容易に設定できる。拡散律
速状態で本発明による窒素酸化物ガスセンサを用いると
非常に安定した酸素ポンプ電流が得られ、安定したガス
検知室(6)内の酸素濃度に保持できる。When a voltage is applied between the outer electrode (7) and the inner electrode (8), oxygen in the atmosphere is introduced from the duct (5) into the gas detection chamber (6) through the oxygen ion permeable layer (2). You. duct
In (5), it is also effective to provide diffusion resistance to oxygen introduction, and to detect the NOx concentration in a diffusion-controlled state in which the oxygen ion current flowing between the outer electrode (7) and the inner electrode (8) generates a limiting current. . The diffusion-controlled state can be easily set by reducing the cross-sectional area of the duct (5) or increasing the duct length. When the nitrogen oxide gas sensor according to the present invention is used in a diffusion-controlled state, a very stable oxygen pump current can be obtained, and a stable oxygen concentration in the gas detection chamber (6) can be maintained.
【００１８】単一電源により同時駆動制御されるヒータ
(15)が底壁(10)及び／又は上壁(3)の外側に設置された
ヒータ基板(18)に埋設される。ヒータ(15)は酸化物から
なる電気絶縁層（図示せず）に挟まれて固体電解質ヒー
タ基板中に形成されるか又は酸化物電気絶縁ヒータ基板
中に形成されてもよい。センサ構造体(1a)の両面にヒー
タを形成した場合、ヒータ(15)に接続されたリード線(1
6, 17)はセンサ構造体(1a)の内部又は外部で並列に接続
される。A heater that is simultaneously driven and controlled by a single power supply
(15) is buried in the heater substrate (18) installed outside the bottom wall (10) and / or the top wall (3). The heater (15) may be formed in a solid electrolyte heater substrate sandwiched between electric insulating layers (not shown) made of oxide, or may be formed in an oxide electric insulating heater substrate. When heaters are formed on both sides of the sensor structure (1a), the lead wires (1) connected to the heater (15)
6, 17) are connected in parallel inside or outside the sensor structure (1a).
【００１９】外側電極(7)と内側電極(8)の間に交流電圧
を同時に印加し、外側電極(7)と内側電極(8)間に存在す
る固体電解質体のインピーダンスを測定し、これをもっ
て温度センサとなし、その出力をヒータ制御回路にフィ
ードバックすることにより、前記温度センサの温度制御
を行うことができる。An AC voltage is simultaneously applied between the outer electrode (7) and the inner electrode (8), and the impedance of the solid electrolyte existing between the outer electrode (7) and the inner electrode (8) is measured. The temperature of the temperature sensor can be controlled by feeding back the output of the temperature sensor to the heater control circuit.
【００２０】[0020]
【発明の実施の形態】以下、混成電位型ＮＯxセンサに
適用した本発明による窒素酸化物ガスセンサの実施の形
態を図１〜図１４について説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a nitrogen oxide gas sensor according to the present invention applied to a mixed potential type NOx sensor will be described below with reference to FIGS.
【００２１】図１に示すように、本発明による窒素酸化
物ガスセンサ(1)は、表面に外側電極(7)が取り付けられ
かつ裏面に内側電極(8)が取り付けられた固体電解質か
ら成る酸素イオン透過層(2)と、ダクト(5)を形成して酸
素イオン透過層(2)から上方に離間して配置された上壁
(3)と、酸素イオン透過層(2)と上壁(3)との間に配置さ
れたインサート(4)と、ガス検知室(6)を形成して酸素イ
オン透過層(2)から下方に離間して配置されかつ底壁(1
0)と、酸素イオン透過層(2)と底壁(10)との間に配置さ
れかつガス検知室(6)を形成するスペーサ(11)と、スペ
ーサ(11)の反対側で酸素イオン透過層(2)と底壁(10)と
の間に配置されかつガス検知室(6)を形成する側壁(12)
とを備えている。少なくとも酸素イオン透過層(2)、底
壁(10)及びスペーサ(11)は、酸素イオン伝導体として一
般的に用いられるイットリア添加のジルコニア酸素イオ
ン伝導体であるが、酸素イオンが連続的に流れ得る固体
電解質でセンサ構造体(1a)として一体に形成された酸素
イオン伝導体であればよい。検知電極(9)に対する参照
極として使用される外側電極(7)は、通常酸素にのみ活
性が高いＰｔ材料を使用して形成される。As shown in FIG. 1, a nitrogen oxide gas sensor (1) according to the present invention comprises an oxygen ion comprising a solid electrolyte having an outer electrode (7) attached to a front surface and an inner electrode (8) attached to a back surface. A permeable layer (2) and an upper wall forming a duct (5) and spaced upward from the oxygen ion permeable layer (2)
(3), an insert (4) disposed between the oxygen ion permeable layer (2) and the upper wall (3), and a gas detection chamber (6) formed below the oxygen ion permeable layer (2). And the bottom wall (1
0), a spacer (11) disposed between the oxygen ion permeable layer (2) and the bottom wall (10) and forming the gas detection chamber (6), and oxygen ion permeable on the opposite side of the spacer (11). Side wall (12) located between layer (2) and bottom wall (10) and forming gas sensing chamber (6)
And At least the oxygen ion permeable layer (2), the bottom wall (10) and the spacer (11) are yttria-doped zirconia oxygen ion conductors generally used as oxygen ion conductors, but oxygen ions flow continuously. Any oxygen ion conductor that is integrally formed as the sensor structure (1a) with the obtained solid electrolyte may be used. The outer electrode (7) used as a reference electrode for the sensing electrode (9) is usually formed using a Pt material having high activity only for oxygen.
【００２２】ガス検知室(6)の外側には酸素に活性な外
側電極(7)がダクト(5)内に設置され、酸素とＮＯxとに
活性な内側電極(8)はガス検知室(6)内で酸素イオン透過
層(2)に固定される。ＮＯx及び酸素に対して活性な検知
電極(9)はガス検知室(6)内で底壁(10)の上面に固定さ
れ、側壁(12)にはガス検知室(6)を大気に連絡するガス
導入口(13)が形成される。いずれも酸素とＮＯxに活性
な検知電極(9)及び内側電極(8)は、ＮＯxと同時に酸素
も存在するガス検知室(6)内に設置される。Outside the gas detection chamber (6), an outer electrode (7) active on oxygen is installed in the duct (5), and the inner electrode (8) active on oxygen and NOx is provided in the gas detection chamber (6). ) Is fixed to the oxygen ion permeable layer (2). A detection electrode (9) active for NOx and oxygen is fixed to the upper surface of the bottom wall (10) in the gas detection chamber (6), and the side wall (12) connects the gas detection chamber (6) to the atmosphere. A gas inlet (13) is formed. The sensing electrode (9) and the inner electrode (8), both active in oxygen and NOx, are installed in a gas sensing chamber (6) in which oxygen is present at the same time as NOx.
【００２３】酸素ポンピングのアノードとしての役割と
同時にＮＯxを電気化学的に変換する触媒電極でもある
内側電極(8)は酸素とＮＯxに対する活性が高いＰｔ−Ｒ
ｈ合金、Ｐｔ−Ｒｕ合金又はＩｒ−Ｒｈ合金を用い、Ｐ
ｔ−Ｒｈ合金又はＩｒ−Ｒｈ合金中のＲｈ組成は０.１
〜１０wt%であることが望ましい。ＮＯxに高い活性を有
する金属酸化物電極には酸素ポンピング機能が低いもの
もあるが、金属酸化物電極に比べて酸素ポンピング機能
自体が高いＰｔ−Ｒｈ合金、Ｐｔ−Ｒｕ合金又はＩｒ−
Ｒｈ合金により内側電極(8)を形成することが望まし
い。外側電極(7)及び内側電極(8)を形成する際に、電極
の多孔度を調整したり、電極の活性点（三相界面）を増
やすために、一般的に通常５〜２０wt%の添加量でジル
コニア固体電解質粉を同時に添加することもある。The inner electrode (8), which functions as an anode for oxygen pumping and also serves as a catalyst electrode for electrochemically converting NOx, has a high activity of Pt-R for oxygen and NOx.
h alloy, Pt-Ru alloy or Ir-Rh alloy,
Rh composition in the t-Rh alloy or the Ir-Rh alloy is 0.1.
Desirably, the content is 10 wt% to 10 wt%. Although some metal oxide electrodes having high activity for NOx have a low oxygen pumping function, a Pt-Rh alloy, a Pt-Ru alloy or an Ir-
It is desirable to form the inner electrode (8) with a Rh alloy. When forming the outer electrode (7) and the inner electrode (8), in order to adjust the porosity of the electrode or to increase the active point (three-phase interface) of the electrode, generally 5 to 20% by weight is usually added. In some cases, the zirconia solid electrolyte powder may be added at the same time.
【００２４】検知電極(9)は、Ｐｔ−Ｒｈ合金若しくは
Ｉｒ−Ｒｈ合金等の貴金属系材料又はＮｉＣｒ2Ｏ4、Ｆ
ｅＣｒ2Ｏ4、ＭｇＣｒ2Ｏ4、Ｃｒ2Ｏ3等のクロム酸化物
系材料から選択され、高いＮＯx活性と高い酸素活性を
有する材料で形成することが必要である。ＮＯx検知電
極(9)を形成する際に、ジルコニア固体電解質粉を同時
に添加して、電極の多孔度を調整しかつ電極の活性点
（三相界面）を増加することが望ましい。ジルコニアの
添加量は、電極性能上３〜２０wt%、好適には５〜１０w
t%が有効である。The detection electrode 9 is made of a noble metal material such as a Pt-Rh alloy or an Ir-Rh alloy, or NiCr 2 O 4 , F
It is necessary to be formed from a material selected from chromium oxide-based materials such as eCr 2 O 4 , MgCr 2 O 4 , and Cr 2 O 3 and having high NOx activity and high oxygen activity. When forming the NOx detection electrode (9), it is desirable to add zirconia solid electrolyte powder at the same time to adjust the porosity of the electrode and increase the active points (three-phase interface) of the electrode. Zirconia is added in an amount of 3 to 20 wt%, preferably 5 to 10 w
t% is valid.
【００２５】カソード電極としての外側電極(7)とアノ
ード電極としての内側電極(8)との間に外部電源により
定電圧を印加し、外側電極(7)と内側電極(8)を用いて電
気化学的に酸素ポンピングを行うと、ダクト(5)内の酸
素が酸素イオン透過層(2)を通じてガス検知室(6)内に供
給されると同時に、ガス検知室(6)内でＮＯxガス中のＮ
Ｏを電気化学的に酸化させてＮＯ2の単一ガスとする。
酸素に活性な外側電極(7)は、大気にのみ通じかつ通常
ＮＯxに対する感度がないため、酸素とＮＯxに活性を有
し混成電位に起因する電位差を発生する検知電極(9)
と、酸素にのみ活性な参照極である外側電極(7)との間
の化学ポテンシャル差（電位差）は、ＮＯx濃度に対応
する出力となり、電位差計(24)で検出される。この際
に、測定ガス中の酸素濃度が皆無でもガス検知室(6)内
の酸素濃度が０.１vol%以上となるように、酸素ポンプ
能力との兼ね合いでガス導入口(13)の断面積及び長さを
調整して、ガス導入口(13)のガス拡散抵抗を設定するこ
とができる。A constant voltage is applied between an outer electrode (7) as a cathode electrode and an inner electrode (8) as an anode electrode by an external power source, and electric power is applied by using the outer electrode (7) and the inner electrode (8). When oxygen pumping is performed chemically, oxygen in the duct (5) is supplied into the gas detection chamber (6) through the oxygen ion permeable layer (2), and at the same time, NOx gas in the gas detection chamber (6) is released. N
O is electrochemically oxidized to a single gas of NO 2 .
Since the outer electrode (7) that is active on oxygen is open only to the atmosphere and generally has no sensitivity to NOx, the detection electrode (9) that is active on oxygen and NOx and generates a potential difference caused by a mixed potential
And a chemical potential difference (potential difference) between the outer electrode (7), which is a reference electrode active only for oxygen, becomes an output corresponding to the NOx concentration, and is detected by the potentiometer (24). At this time, the cross-sectional area of the gas inlet (13) is determined in consideration of the oxygen pump capacity so that the oxygen concentration in the gas detection chamber (6) becomes 0.1 vol% or more even when the oxygen concentration in the measurement gas is completely absent. By adjusting the length and length, the gas diffusion resistance of the gas inlet (13) can be set.
【００２６】２０.９vol%酸素が存在する大気に連絡す
るダクト(5)は、常に酸素ポンプにより大気中からガス
検知室(6)内に酸素を供給できるが、一定の酸素濃度が
存在する雰囲気に通ずるダクトであれば大気でなくても
よい。また、酸素ポンピング量に関わらず、ダクト(5)
による酸素ガスの拡散抵抗が過度のガス拡散律速状態に
なってはならない。そのために、所定のセンサ作動温度
での酸素ポンピング量によって過度のガス拡散律速状態
にならないようにダクト(5)の断面積とダクト長を設計
する。酸素に活性な外側電極(7)は、例えばＮＯx等の他
のガスに対して活性でも酸素活性が充分であればよい。The duct (5), which communicates with the atmosphere containing 20.9 vol% oxygen, can always supply oxygen from the atmosphere into the gas detection chamber (6) by the oxygen pump. The air does not have to be air as long as it is a duct that leads to. Also, regardless of the amount of oxygen pumping, the duct (5)
The diffusion resistance of oxygen gas by the gas must not be excessively controlled by gas diffusion. For that purpose, the cross-sectional area and the duct length of the duct (5) are designed so that the gas diffusion rate is not excessively controlled by the oxygen pumping amount at a predetermined sensor operating temperature. The outer electrode (7) that is active on oxygen may be active on other gases such as NOx, for example, provided that the oxygen activity is sufficient.
【００２７】ガス検知室(6)内の内側電極(8)とＮＯx検
知電極(9)との配置関係は、本発明による窒素酸化物ガ
スセンサの特性に大きい影響を及ぼす。まず、ガス検知
室(6)の酸素イオン透過層(2)の内側電極設置面の面積に
対し、内側電極(8)の占有比率が４０%に満たないとＮＯ
x変換効率が低く、酸素ポンピング量が不充分となり、
ガス検知室(6)内の酸素濃度を０.１%以上に保持できな
い。従って、図１に示すように、酸素ポンピング機能が
低下しないように、酸素ポンピング機能とＮＯxのＮＯ2
化変換機能を同時に行う内側電極(8)の面積は、ガス検
知室(6)の内側電極設置面の面積に対して４０%以上を占
めることが必要である。また、内側電極(8)に対向する
検知電極(9)の面積は内側電極(8)の面積より小さい。内
側電極(8)を設置したガス検知室(6)内でガス導入口(13)
側から測定ガスの侵入方向の後方部に検知電極(9)を配
置すると、測定ガス中のＨＣ等の干渉ガスをガス検知室
(6)の前段にて酸化除去できるため、センサ検知特性を
改善できる。The positional relationship between the inner electrode (8) and the NOx detection electrode (9) in the gas detection chamber (6) greatly affects the characteristics of the nitrogen oxide gas sensor according to the present invention. First, if the occupation ratio of the inner electrode (8) is less than 40% of the area of the inner electrode installation surface of the oxygen ion permeable layer (2) of the gas detection chamber (6), NO
x Low conversion efficiency, insufficient oxygen pumping amount,
The oxygen concentration in the gas detection chamber (6) cannot be maintained at 0.1% or more. Accordingly, as shown in FIG. 1, so that the oxygen pumping function is not reduced, the oxygen pumping function and NOx NO 2
It is necessary that the area of the inner electrode (8) that simultaneously performs the conversion function occupies 40% or more of the area of the inner electrode installation surface of the gas detection chamber (6). Further, the area of the detection electrode (9) facing the inner electrode (8) is smaller than the area of the inner electrode (8). Gas inlet (13) in the gas detection chamber (6) where the inner electrode (8) is installed
When the detection electrode (9) is placed at the rear of the measurement gas from the side, the interference gas such as HC in the measurement gas is removed from the gas detection chamber.
Oxidation can be removed before (6), so that sensor detection characteristics can be improved.
【００２８】ＮＯx基準極となる外側電極(7)が曝される
ダクト(5)内の大気中の酸素濃度は一定である。ダクト
(5)内の酸素濃度が変動すると外側電極(7)の電極電位が
変動し、基準電位がふらつく原因となる。そのため、ダ
クト(5)の拡散抵抗設計によって酸素ポンピングにおけ
る拡散律速を防止することが好ましい。しかしながら、
測定雰囲気中の酸素濃度が余り大きく変動しないような
状況では、逆に酸素ポンプ電流に限界電流を生じさせ、
酸素ポンプ電極の性能変動が大きい場合に比べて、常に
安定した酸素量をガス検知室(6)内に供給する方が好ま
しい場合がある。The oxygen concentration in the atmosphere in the duct (5) to which the outer electrode (7) serving as the NOx reference electrode is exposed is constant. duct
If the oxygen concentration in (5) fluctuates, the electrode potential of the outer electrode (7) fluctuates, causing the reference potential to fluctuate. Therefore, it is preferable to prevent diffusion-limiting in oxygen pumping by designing the diffusion resistance of the duct (5). However,
In a situation where the oxygen concentration in the measurement atmosphere does not fluctuate too much, on the contrary, a limit current is generated in the oxygen pump current,
In some cases, it is preferable to always supply a stable amount of oxygen into the gas detection chamber (6) as compared with the case where the performance fluctuation of the oxygen pump electrode is large.
【００２９】本発明による窒素酸化物ガスセンサを製造
する際に、３〜８molのイットリア（Ｙ2Ｏ3）を添加し
たジルコニア（ＺｒＯ2）粉をＰＶＡ等の有機結合剤
と、可塑剤及び有機溶剤とでボールミル混合を行い、ジ
ルコニアのスラリーを得る。粉末粒子の分散性を改善す
る分散剤を混合物に添加してもよい。ドクターブレード
を備えたシート成形機を使用してＰＥＴフィルム上に数
１００μmの厚みを有するジルコニアのスラリーを塗布
成形する。ＰＥＴフィルム上に塗布されたスラリーから
溶剤を乾燥除去すると、非常に柔軟性に富む状態とな
り、ジルコニアのグリーンシートが得られる。３〜８mo
lのイットリア（Ｙ2Ｏ3）が予め添加されるので、グリ
ーンシートに酸素イオン伝導性を付与することができ
る。更に加温しながらジルコニアのグリーンシート同士
を積層圧着すると、相互に強く接着することができる。
グリーンシート積層体中に内部空間を形成するためには
その部分に脱脂温度以下で昇華するテオブロミン等を充
填しておけば、脱脂時に内部空間が形成される。勿論、
脱脂時にはグリーンシート中の有機結合剤が酸化除去さ
れる。脱脂後１４００℃前後の温度で焼成すると、ガス
検知室(6)及びダクト(5)を有するセンサ構造体(1a)が得
られる。When manufacturing the nitrogen oxide gas sensor according to the present invention, zirconia (ZrO 2 ) powder containing 3 to 8 mol of yttria (Y 2 O 3 ) is mixed with an organic binder such as PVA, a plasticizer and an organic solvent. And ball mill mixing to obtain a zirconia slurry. A dispersant that improves the dispersibility of the powder particles may be added to the mixture. Using a sheet forming machine equipped with a doctor blade, a slurry of zirconia having a thickness of several 100 μm is applied and formed on a PET film. When the solvent is dried and removed from the slurry applied on the PET film, the slurry becomes very flexible and a zirconia green sheet is obtained. 3-8mo
Since l yttria (Y 2 O 3 ) is added in advance, oxygen ion conductivity can be imparted to the green sheet. If zirconia green sheets are laminated and pressed together while further heating, they can be strongly bonded to each other.
In order to form an internal space in the green sheet laminate, if the portion is filled with theobromine or the like that sublimes at a temperature lower than the degreasing temperature, the internal space is formed at the time of degreasing. Of course,
During degreasing, the organic binder in the green sheet is oxidized and removed. When calcination is performed at a temperature of about 1400 ° C. after degreasing, a sensor structure (1a) having a gas detection chamber (6) and a duct (5) is obtained.
【００３０】図２に示すように、ガス検知室(6)内にア
ルミナ等の多孔質体(6a)を充填設置して、ガス拡散抵抗
を更に増大することができる。図３は、ＮＯxに対して
活性な変換ポンプ部(8a)と酸素に対して活性な酸素ポン
プ部(8b)とを接続する内側電極(8)の２相並列電極構造
を示す。２相並列電極構造は、内側電極(8)のリード線
本数を増やさずに内側電極(8)の酸素ポンピング機能を
改善するのに有効であるが、酸素に対して活性な内側電
極(8)の酸素ポンプ部(8b)をガス導入口(13)側に設置す
ることが必要である。As shown in FIG. 2, a gas diffusion resistance can be further increased by filling and installing a porous body (6a) such as alumina in the gas detection chamber (6). FIG. 3 shows a two-phase parallel electrode structure of the inner electrode (8) connecting the conversion pump section (8a) active for NOx and the oxygen pump section (8b) active for oxygen. The two-phase parallel electrode structure is effective for improving the oxygen pumping function of the inner electrode (8) without increasing the number of lead wires of the inner electrode (8). It is necessary to install the oxygen pump section (8b) on the gas inlet (13) side.
【００３１】図４は、ガス検知室(6)をＮＯx検知電極
(9)を設置するガス検知室(6b)と、内部ガス空間(6c)と
に分割し、内部ガス空間(6c)に触媒層(25)を配置した例
を示す。触媒層(25)は、測定ガス中のＨＣ、ＣＯ等の干
渉ガスを更に容易に酸化無害化し、干渉ガスを容易に除
去できる酸化触媒体である。図５は、酸化触媒層又は酸
化触媒を担持した多孔質体により内部ガス通路(6c)を構
成し干渉ガスを更に容易に除去できる例を示す。FIG. 4 shows a gas detection chamber (6) connected to a NOx detection electrode.
An example is shown in which a gas detection chamber (6b) in which (9) is installed is divided into an internal gas space (6c), and a catalyst layer (25) is arranged in the internal gas space (6c). The catalyst layer (25) is an oxidation catalyst body that can more easily oxidize and detoxify the interference gas such as HC and CO in the measurement gas, and can easily remove the interference gas. FIG. 5 shows an example in which the internal gas passage (6c) is constituted by an oxidation catalyst layer or a porous body supporting the oxidation catalyst, and the interference gas can be more easily removed.
【００３２】これらの触媒層又は触媒を担持した多孔質
体は触媒粉末に直接有機結合材、有機溶剤等を混ぜてペ
ーストとし、スクリーン印刷によって形成することがで
きる。金属酸化物触媒では通常、焼成収縮量が小さくジ
ルコニア基体との密着性に劣るので、ジルコニア粉末を
同時に添加して密着性を改善することが行われる。この
場合のジルコニア添加量は５〜５０wt%、より好ましく
は１０〜３０wt%とする。同様に貴金属触媒の場合、貴
金属のみでもよいが、多孔質にしたりジルコニア基体と
の収縮差の整合を図るにはジルコニア粉末を添加するこ
とがより好ましい。また、より多孔質にするにはジルコ
ニア粉末の代わりにアルミナ粉末を添加したペーストを
用いることができる。ジルコニア又はアルミナの添加量
は１０〜９５wt%、より好ましくは１０〜９０wt%とす
る。The catalyst layer or the porous body supporting the catalyst can be formed by directly mixing an organic binder, an organic solvent, and the like into the catalyst powder to form a paste, and forming the paste by screen printing. The metal oxide catalyst usually has a small shrinkage in firing and poor adhesion to a zirconia substrate. Therefore, zirconia powder is added at the same time to improve the adhesion. In this case, the added amount of zirconia is 5 to 50% by weight, more preferably 10 to 30% by weight. Similarly, in the case of a noble metal catalyst, only a noble metal may be used, but it is more preferable to add zirconia powder in order to make the catalyst porous and to match the shrinkage difference with the zirconia substrate. Further, in order to make it more porous, a paste to which alumina powder is added instead of zirconia powder can be used. The added amount of zirconia or alumina is 10 to 95 wt%, more preferably 10 to 90 wt%.
【００３３】本発明による窒素酸化物ガスセンサは、基
本的に測定雰囲気中の酸素濃度に余り依存せず、ＮＯx
濃度を検出できる混成電位検知型の特徴を有するが、測
定ガス中で極端に変動する酸素濃度により多少の影響を
受ける。本発明の窒素酸化物ガスセンサに要求される検
知精度が不十分なとき、図６に示すように、ガス検知室
(6)外の測定ガス中に通じる固体電解質の一面に酸素に
のみ活性な付加電極(14)を形成する。付加電極(14)は、
酸素に活性なＰｔ電極材料を用い、必要に応じてＰｔ電
極中にジルコニア固体電解質を分散添加することができ
る。底壁(10)の下方に形成された別室(6d)内に配置され
た付加電極(14)を底壁(10)に固定する。外側電極(7)と
付加電極(14)との間の酸素濃度に基づく起電力を測定し
て、測定ガス中の酸素濃度を検知し、その検知出力を用
いてＮＯx出力を補正して、大幅に検知精度を改善する
ことができる。例えば、測定ガス中の酸素濃度の変動に
対応するガス検知室(6)内の酸素濃度変化データとその
酸素濃度のＮＯx出力へ与える大きさを図示しない記憶
装置に記憶し、瞬時に補正計算しながら実質的にリアル
タイムでＮＯx濃度を測定することができる。The nitrogen oxide gas sensor according to the present invention basically does not largely depend on the oxygen concentration in the measurement atmosphere,
Although it has the feature of the hybrid potential detection type that can detect the concentration, it is somewhat affected by the extremely fluctuating oxygen concentration in the measurement gas. When the detection accuracy required for the nitrogen oxide gas sensor of the present invention is insufficient, as shown in FIG.
(6) An additional electrode (14) that is active only on oxygen is formed on one surface of the solid electrolyte communicating with the outside measurement gas. The additional electrode (14)
Using a Pt electrode material active on oxygen, a zirconia solid electrolyte can be dispersed and added to the Pt electrode as needed. An additional electrode (14) arranged in a separate chamber (6d) formed below the bottom wall (10) is fixed to the bottom wall (10). Measure the electromotive force based on the oxygen concentration between the outer electrode (7) and the additional electrode (14), detect the oxygen concentration in the measurement gas, correct the NOx output using the detected output, and significantly In addition, the detection accuracy can be improved. For example, the oxygen concentration change data in the gas detection chamber (6) corresponding to the fluctuation of the oxygen concentration in the measurement gas and the magnitude of the oxygen concentration given to the NOx output are stored in a storage device (not shown), and the correction is instantaneously calculated. However, the NOx concentration can be measured substantially in real time.
【００３４】また、図７に示すように、外側電極(7)と
付加電極(14)との間の酸素濃度差に基づく起電力を検知
する場合、ガス検知室(6)内に付加電極(14)を設置する
ことによりガス検知室(6)内の酸素濃度変動を直接検知
できる。これにより、ＮＯx出力を補正することもでき
るが、その場合、検知電極(9)の近傍に付加電極(14)を
設置することが望ましい。As shown in FIG. 7, when the electromotive force based on the oxygen concentration difference between the outer electrode (7) and the additional electrode (14) is detected, the additional electrode (7) is placed in the gas detection chamber (6). By installing 14), the oxygen concentration fluctuation in the gas detection chamber (6) can be directly detected. This makes it possible to correct the NOx output, but in this case, it is desirable to provide the additional electrode (14) near the detection electrode (9).
【００３５】図１〜図７の窒素酸化物ガスセンサでは、
実際のガス検出時には何らかのセンサ素子を加熱する手
段が必要である。図８は、ヒータ(15)を埋設したヒータ
基板との一体型の窒素酸化物ガスセンサを示す。電気抵
抗発熱体により構成されるヒータ(15)は、固体電解質の
平板により形成された底板(10)に固着されるヒータ基板
(18)に直接埋設された構造を有する。ヒータ基板(8)は
アルミナ等の絶縁基板でもセンサ素子材料となる固体電
解質基板でもよいが、固体電解質ヒータ基板の場合、ヒ
ータと固体電解質との間に図示しないアルミナ等の絶縁
層を設ける。図８では、図６に示すように、検知室(6)
から隔離された別室(6d)内に付加電極(14)を設置しなく
てもよいが、ヒータ(15)との一体構造では別室(6d)を形
成し格納するほうが製造上効率がよい。In the nitrogen oxide gas sensor shown in FIGS.
At the time of actual gas detection, some means for heating the sensor element is required. FIG. 8 shows a nitrogen oxide gas sensor integrated with a heater substrate in which a heater (15) is embedded. A heater (15) composed of an electric resistance heating element is a heater substrate fixed to a bottom plate (10) formed of a solid electrolyte flat plate.
It has a structure directly buried in (18). The heater substrate (8) may be an insulating substrate such as alumina or a solid electrolyte substrate serving as a sensor element material. In the case of a solid electrolyte heater substrate, an insulating layer (not shown) such as alumina is provided between the heater and the solid electrolyte. In FIG. 8, as shown in FIG.
The additional electrode (14) may not be installed in the separate room (6d) isolated from the outside, but it is more efficient to form and store the separate room (6d) and store it in an integrated structure with the heater (15).
【００３６】図９は、図６のセンサ構成にヒータ(15)を
含むヒータ基板(18)をセンサ構造体(1a)の上面及び下面
の両面に一体接合したヒータ一体型の窒素酸化物ガスセ
ンサの例を示す。図９に示すように、ガス検知室(6)の
上部及び下部の両面にヒータ(15)を一体に構成し、２対
のヒータ(15)を電気的に並列動作するとその熱制御性が
大幅に増し、また、電源へのリード線(17)を増加せずに
作製することができる。図９に示す例では、センサ構造
体(1a)中にスルーホール(16)を形成し、スルーホール(1
6)を通じて２つのヒータ(15)のリード線(17)を並列に接
続する。更に、ヒータ(15)の外側に形成した集電体(19)
をヒータグランドに接続して、ヒータ(15)からの漏れ電
流を集電体(19)により吸収することができる。更に、窒
素酸化物ガスセンサの温度を制御するために、外側電極
(7)と内側電極(8)の間に交番電圧を印加し、外側電極
(7)と内側電極(8)との間のジルコニア固体電解質のバル
クインピーダンスを測定しその大きさによりヒータ電圧
をフィードバック制御できると共に、６本のリード線(2
0, 21, 22, 26, ２本の17)でセンサ機能を作動できる効
果がある。FIG. 9 shows a heater-integrated nitrogen oxide gas sensor in which a heater substrate (18) including a heater (15) is integrally joined to both upper and lower surfaces of the sensor structure (1a) in the sensor configuration of FIG. Here is an example. As shown in FIG. 9, heaters (15) are integrally formed on both upper and lower surfaces of the gas detection chamber (6), and when two pairs of heaters (15) are electrically operated in parallel, the heat controllability is greatly increased. It can be manufactured without increasing the number of leads (17) to the power supply. In the example shown in FIG. 9, a through hole (16) is formed in the sensor structure (1a), and the through hole (1) is formed.
The lead wires (17) of the two heaters (15) are connected in parallel through 6). Furthermore, a current collector (19) formed outside the heater (15)
Is connected to the heater ground, and the leakage current from the heater (15) can be absorbed by the current collector (19). Further, the outer electrode is used to control the temperature of the nitrogen oxide gas sensor.
(7) Apply alternating voltage between the inner electrode (8) and the outer electrode.
The bulk impedance of the zirconia solid electrolyte between (7) and the inner electrode (8) is measured and the heater voltage can be feedback-controlled according to its magnitude.
There is an effect that the sensor function can be operated in 0, 21, 22, 26, and two 17).
【００３７】[0037]
【実施例】以下、本発明の実施例を詳細に説明するが、
本発明は下記実施例に限定されず、同一思想を含む全て
の発明を含む。Hereinafter, embodiments of the present invention will be described in detail.
The present invention is not limited to the following examples, but includes all inventions including the same idea.
【００３８】[例１]図８に示す窒素酸化物ガスセンサの
サンプルを作製するため、イットリア６mol%を添加した
ジルコニアのグリーンシートを前記の方法で準備した。
厚み約２００μmのジルコニアグリーンシートをセンサ
基板の焼成前サイズに切断し、ガス検知室(6)やダクト
(5)を形成する部位に窓開け加工を同時に行った。切断
した各グリーンシートに電極、リード導体、ヒータ(15)
等をスクリーン印刷機にて印刷形成した。外側電極
(7)、ヒータ(15)、集電体(19)の印刷材料にはＰｔペー
ストを用い、内側電極(8)にはＲｈ添加量が３wt%のＰｔ
−Ｒｈ合金ペーストを用い、付加電極(14)にはＮｉＣｒ
2Ｏ4の酸化物ペーストを用いた。外側電極(7)のＰｔペ
ースト及び内側電極(8)のＰｔ−Ｒｈ合金ペーストにジ
ルコニア固体電解質粉末を約１０wt%添加して各電極の
多孔度を調整した。Ｐｔ線をリード部に挿入しながら印
刷形成した各グリーンシートを図８の積層状態に順次重
ね合わせ、温水中で静水圧プレスによるラミネート処理
を行った。得られた積層体の脱脂を約６００℃で、続い
て焼成を１４００℃の高温雰囲気で行った。Example 1 To prepare a sample of the nitrogen oxide gas sensor shown in FIG. 8, a zirconia green sheet to which 6 mol% of yttria was added was prepared by the above-described method.
A zirconia green sheet with a thickness of about 200 μm is cut to the size before firing the sensor substrate, and the gas detection chamber (6) and duct
The window forming process was performed simultaneously on the portion where (5) was formed. Electrodes, lead conductors, and heaters on each cut green sheet (15)
And the like were printed by a screen printing machine. Outer electrode
(7) Pt paste is used for the printing material of the heater (15) and the current collector (19), and the inner electrode (8) is made of Pt containing 3 wt% of Rh.
-Rh alloy paste, NiCr for additional electrode (14)
An oxide paste of 2 O 4 was used. About 10 wt% of zirconia solid electrolyte powder was added to the Pt paste of the outer electrode (7) and the Pt-Rh alloy paste of the inner electrode (8) to adjust the porosity of each electrode. Each green sheet printed and formed while inserting the Pt wire into the lead portion was sequentially superimposed on the lamination state of FIG. 8, and a lamination process was performed in hot water by a hydrostatic pressure press. The obtained laminate was degreased at about 600 ° C., and subsequently baked in a high-temperature atmosphere at 1400 ° C.
【００３９】作製したセンササンプルを測定用のホルダ
ーにセットし、図８に略示する測定回路及び制御回路に
接続してセンサ特性を評価した。外側電極(7)と内側電
極(8)の間には定電圧の直流電源を接続し、外側電極(7)
を負極（カソード）、内側電極(8)を正極（アノード）
として０.６Vの定電圧を印加した。同時に外側電極(7)
と検知電極(9)との間に入力インピーダンス１０MΩ以上
の電位差計を接続した。また、図８には図示しないが、
外側電極(7)と内側電極(8)間のジルコニア基板のバルク
インピーダンスを測定する回路を並列に接続し、センサ
温度信号を取り出した。更に、ヒータ(15)からの２本の
リード線(17)間に直流電源を接続した。The prepared sensor sample was set on a holder for measurement and connected to a measurement circuit and a control circuit schematically shown in FIG. 8 to evaluate sensor characteristics. Connect a constant voltage DC power supply between the outer electrode (7) and the inner electrode (8), and connect the outer electrode (7)
Is the negative electrode (cathode) and the inner electrode (8) is the positive electrode (anode)
And a constant voltage of 0.6 V was applied. At the same time outer electrode (7)
A potentiometer having an input impedance of 10 MΩ or more was connected between the sensor and the detection electrode (9). Although not shown in FIG. 8,
A circuit for measuring the bulk impedance of the zirconia substrate between the outer electrode (7) and the inner electrode (8) was connected in parallel, and a sensor temperature signal was taken out. Further, a DC power supply was connected between two lead wires (17) from the heater (15).
【００４０】センサ作動温度が５５０℃になるようにヒ
ータ(15)をフィードバック制御し、１００ppmのＮＯ
と、１００ppmのＮＯ2と、５０ppmのＮＯ及び５０ppmの
ＮＯ2とからなる３水準のＮＯxガスに対する出力を測定
した。ＮＯxガスは他に酸素０.４%、残りは窒素からな
るドライガスである。また、外側電極(7)と内側電極(8)
間に流れる酸素イオン電流（ポンピング電流）をポンプ
電圧をゆっくりとスキャンしながら測定した。The heater (15) is feedback-controlled so that the sensor operating temperature becomes 550 ° C.
, 100 ppm NO 2 , and 50 ppm NO and 50 ppm NO 2 , the output for three levels of NOx gas was measured. The NOx gas is a dry gas consisting of 0.4% oxygen and the remainder nitrogen. Also, the outer electrode (7) and the inner electrode (8)
The oxygen ion current (pumping current) flowing therebetween was measured while slowly scanning the pump voltage.
【００４１】まず、図１０は、ポンプ電圧に対するポン
プ電流特性を示す。この結果から、本実施例での窒素酸
化物ガスセンサのサンプルでは、ダクト(5)の酸素ガス
拡散抵抗は充分小さく、外側電極(7)と内側電極(8)間に
印加された電圧は０〜１.０Vの間で拡散律速されていな
いことが分かる。このようなガス拡散抵抗を有するダク
ト(5)を用いて、外側電極(7)と内側電極(8)間に外部定
電圧０.６Vを印加しながら外側電極(7)と検知電極(9)と
の間の電位差をＮＯx出力として図１１に示す。図１１
は、ＮＯ及びＮＯ2に関係なく総ＮＯx濃度を検知できる
ことを示す。FIG. 10 shows pump current characteristics with respect to pump voltage. From this result, in the sample of the nitrogen oxide gas sensor in this example, the oxygen gas diffusion resistance of the duct (5) was sufficiently small, and the voltage applied between the outer electrode (7) and the inner electrode (8) was 0 to 0. It can be seen that diffusion control was not performed between 1.0V. Using the duct (5) having such gas diffusion resistance, the outer electrode (7) and the sensing electrode (9) are applied while applying an external constant voltage of 0.6 V between the outer electrode (7) and the inner electrode (8). 11 is shown in FIG. 11 as a NOx output. FIG.
It is shown to be able to detect the total NOx concentration regardless NO and NO 2.
【００４２】[例２]検知電極(9)に直接対向する内側電
極(8)の面に３wt%Ｒｈを添加したＰｔ−Ｒｈ合金電極膜
を形成し、検知電極(9)に直接対向しない面にＰｔ電極
膜を形成した２相並列電極としたこと以外は、例１とほ
ぼ同様なセンサ構造を有する例２のサンプルを作製し
た。内側電極(8)の構成は図３と同一である。このセン
サ構成と比較するため、例１で作製したサンプルを比較
サンプルＡとした。サンプルＡと例２のサンプルのガス
導入口(13)のサイズ、電極面積は同一である。サンプル
Ａ及び例２のサンプルを５５０℃の作動温度に制御し、
外側電極(7)（カソード）と内側電極(8)（アノード）間
に一定電圧の０.５Vを印加しながら、２００ppmのＮＯ
ガス（酸素０%〜１５%、残部は窒素）を測定系に導入
し、測定ガス中の酸素濃度を変えながらＮＯx出力を測
定した。酸素濃度変動に対するＮＯx出力特性を示す図
１２より、測定ガス雰囲気中の酸素濃度が大きく変動し
ても、２相並列電極構造の内側電極(8)を有する例２の
サンプルの方が、明らかにＮＯx出力に大きな影響を受
けないことが分かる。これは、２相並列構造の内側電極
(8)により酸素ポンピング機能が大きく改善されること
を示す。[Example 2] A Pt-Rh alloy electrode film to which 3 wt% Rh was added was formed on the surface of the inner electrode (8) directly facing the detection electrode (9), and the surface not directly facing the detection electrode (9). A sample of Example 2 having a sensor structure almost the same as that of Example 1 except that a two-phase parallel electrode having a Pt electrode film formed thereon was prepared. The configuration of the inner electrode (8) is the same as in FIG. For comparison with this sensor configuration, the sample manufactured in Example 1 was used as Comparative Sample A. The size of the gas inlet (13) and the electrode area of the sample A and the sample of Example 2 are the same. Controlling the sample A and the sample of example 2 to an operating temperature of 550 ° C.,
While applying a constant voltage of 0.5 V between the outer electrode (7) (cathode) and the inner electrode (8) (anode), 200 ppm NO
Gas (0% to 15% oxygen, the balance being nitrogen) was introduced into the measurement system, and the NOx output was measured while changing the oxygen concentration in the measurement gas. From FIG. 12 showing the NOx output characteristics with respect to the oxygen concentration fluctuation, even if the oxygen concentration in the measurement gas atmosphere fluctuates greatly, the sample of Example 2 having the inner electrode (8) of the two-phase parallel electrode structure is clearly clearer. It turns out that it is not greatly affected by the NOx output. This is a two-phase parallel inner electrode
(8) shows that the oxygen pumping function is greatly improved.
【００４３】[例３]内側電極(8)の面積がガス検知室(6)
の内側電極設置面の２０%〜８０%となりかつ図８中の検
知電極(9)の真上に内側電極(8)を配置して例１の各セン
ササンプルを作製した。また、内側電極(8)の面積が７
０%のときの検知電極(9)をガス検知室(6)の前方と後方
に配置したサンプルも作製した。これらのサンプルによ
り、内側電極(8)の最適面積率と検知電極(9)の設置位置
の影響を調べ、各サンプルについて１００ppmのＮＯと
１００ppmのＮＯ2との出力を比較した。測定ガスは酸素
０.４%、残部は窒素ガスからなり、外側電極(7)と内側
電極(8)間に０.５Vの電圧を印加した。図１３に各サン
プルにおける内側電極(8)の面積率に対する測定結果を
示す。図１３は、検知電極(9)を設置したガス検知室(6)
の内側電極設置面に占める内側電極(8)の面積率が約４
０%以上でないと、ＮＯとＮＯ2ガスの出力レベルが異な
り総ＮＯx濃度を精度良く検知できないことを示す。ま
た、面積率が約４０%に満たないと、ＮＯx出力自体の大
きさも低下することが明らかである。従って、内側電極
(8)の面積占有率を４０%以上にすることが特性上望まし
い。[Example 3] The area of the inner electrode (8) was changed to the gas detection chamber (6).
Each of the sensor samples of Example 1 was prepared by arranging the inner electrode (8) at 20% to 80% of the inner electrode installation surface and directly above the detection electrode (9) in FIG. The area of the inner electrode (8) is 7
A sample was also prepared in which the detection electrode (9) at 0% was disposed in front and behind the gas detection chamber (6). These samples, investigated the effect of the installation position of the optimum area ratio and the detection electrode of the inner electrode (8) (9), and compares the output of the NO 2 in the NO and 100ppm of 100ppm for each sample. The measurement gas consisted of 0.4% of oxygen and the remainder nitrogen gas. A voltage of 0.5 V was applied between the outer electrode (7) and the inner electrode (8). FIG. 13 shows the measurement results for the area ratio of the inner electrode (8) in each sample. FIG. 13 shows a gas detection chamber (6) in which a detection electrode (9) is installed.
The area ratio of the inner electrode (8) to the inner electrode installation surface of
If it is not 0% or more, the output levels of NO and NO 2 gases are different, indicating that the total NOx concentration cannot be detected with high accuracy. When the area ratio is less than about 40%, it is apparent that the magnitude of the NOx output itself also decreases. Therefore, the inner electrode
It is desirable in terms of characteristics that the area occupancy of (8) be 40% or more.
【００４４】表１は、面積占有率７０%の内側電極(8)で
は検知電極(9)の配置の与える影響を示す。同じ内側電
極(8)の面積占有率でも、ガス導入口(13)の直後にガス
検知室(6)を形成する図８のセンサ構造では、検知電極
(9)がガス導入口(13)側に配置される場合には、総ＮＯx
検知特性が低下することが分かる。また、測定ガス中に
含まれる例えば、排ガス中のＨＣ又はＣＯ等の干渉ガス
の影響が大きくなることも明らかである。ガス検知室
(6)内のガス導入口(13)側から検知電極(9)の先端までの
距離をガス検知室(6)の奥行長さの３０%以上、望ましく
は４０%以上に設置することが必要である。因みに、例
１では検知電極(9)は、５０%の位置に配置される。Table 1 shows the influence of the arrangement of the sensing electrodes 9 on the inner electrodes 8 having an area occupancy of 70%. Even with the same area occupancy of the inner electrode (8), in the sensor structure of FIG. 8 in which the gas detection chamber (6) is formed immediately after the gas inlet (13), the detection electrode
When (9) is arranged on the gas inlet (13) side, the total NOx
It can be seen that the detection characteristics are reduced. It is also clear that the influence of interference gas such as HC or CO in the exhaust gas contained in the measurement gas increases. Gas detection chamber
(6) The distance from the gas inlet (13) side to the tip of the detection electrode (9) in the gas detection chamber (6) must be at least 30%, preferably at least 40%, of the depth of the gas detection chamber (6). It is. Incidentally, in Example 1, the detection electrode (9) is arranged at a position of 50%.
【００４５】[0045]
【表１】 [Table 1]
【００４６】[例４]例１と同様のセンサ構造で、検知電
極(9)の材料を各種用意し、酸素０.４%、残部は窒素ガ
スからなる１５０ppmのＮＯガスと、これと同様な１５
０ppmのＮＯ 2ガスの検知出力を測定した。測定結果を示
す表２から明らかなように、例４で用いた検知電極(9)
材料では優れた総ＮＯx濃度を検知できることが分か
る。Example 4 With the same sensor structure as in Example 1,
Prepare various materials for the electrode (9), 0.4% oxygen, and the rest is nitrogen gas.
NO gas consisting of 150 ppm
0 ppm NO TwoThe gas detection output was measured. Show measurement results
As is clear from Table 2, the sensing electrode (9) used in Example 4 was used.
Find out that materials can detect excellent total NOx concentration
You.
【００４７】[0047]
【表２】 [Table 2]
【００４８】[例５]例１と同様のセンサ構造で、内側電
極(8)の材料を各種用意し、酸素０.４%、残部窒素ガス
からなる１５０ppmのＮＯガスと、これと同様な１５０p
pmのＮＯ2ガスの検知出力を測定した。表３に示す測定
結果から明らかなように、例５で用いた内側電極(8)の
材料では優れた総ＮＯx濃度検知ができることが分か
る。Example 5 A sensor structure similar to that of Example 1 was used, and various materials for the inner electrode (8) were prepared. A 150 ppm NO gas consisting of 0.4% oxygen and the remaining nitrogen gas was mixed with a 150 ppm NO gas.
The detection output of NO 2 gas at pm was measured. As is clear from the measurement results shown in Table 3, it can be seen that the material of the inner electrode (8) used in Example 5 can detect excellent total NOx concentration.
【００４９】[0049]
【表３】 [Table 3]
【００５０】[例６]ガス導入口(13)の断面積と長さを調
整し、ガス拡散抵抗は小さい方からサンプルI＜II＜III
＜IVと４水準を準備して、例１と同様な作製方法により
図７のセンサ構造を有する窒素酸化物ガスセンサのサン
プルを作製した。また、ガス検知室(6)内の酸素濃度を
測定するＰｔ付加電極(14)をガス検知室(6)内に同時形
成した。このセンササンプルを評価装置にセットし、外
側電極(7)と内側電極(8)の間に定電圧０.６Vを印加し
た。測定ガス中の酸素濃度を０〜１５vol%に変化させ、
ガス検知室(6)内の酸素濃度を測定した。図１４は、測
定ガス中の酸素濃度とガス検知室内の酸素濃度との関係
に対するガス導入口のガス拡散抵抗の影響を示すグラフ
である。図１４に示す測定結果から明らかなように、ガ
ス導入口(13)にサンプルII以上のガス拡散抵抗を設定す
ると、測定雰囲気中の酸素濃度が０%でもガス検知室(6)
内の酸素濃度を０.１vol%以上に保持できる。また、Ｎ
Ｏ2ガス１００ppmを測定したところ、ガス検知室(6)内
の酸素濃度が約０.０３%のときにガス応答性が非常に悪
く、明らかに０.１%以上のときに比べ、ガス検知性能が
悪化することが分かった。[Example 6] The cross-sectional area and length of the gas inlet (13) were adjusted, and the sample I <II <III
<IV and four levels were prepared, and a sample of the nitrogen oxide gas sensor having the sensor structure of FIG. Further, a Pt additional electrode (14) for measuring the oxygen concentration in the gas detection chamber (6) was simultaneously formed in the gas detection chamber (6). The sensor sample was set in an evaluation device, and a constant voltage of 0.6 V was applied between the outer electrode (7) and the inner electrode (8). Change the oxygen concentration in the measurement gas from 0 to 15 vol%,
The oxygen concentration in the gas detection chamber (6) was measured. FIG. 14 is a graph showing the effect of the gas diffusion resistance of the gas inlet on the relationship between the oxygen concentration in the measurement gas and the oxygen concentration in the gas detection chamber. As is clear from the measurement results shown in FIG. 14, when a gas diffusion resistance of the sample II or higher is set at the gas inlet (13), even if the oxygen concentration in the measurement atmosphere is 0%, the gas detection chamber (6)
The oxygen concentration in the inside can be kept at 0.1 vol% or more. Also, N
When 100 ppm of O 2 gas was measured, the gas responsiveness was very poor when the oxygen concentration in the gas detection chamber (6) was about 0.03%. It was found that performance deteriorated.
【００５１】[例７]例１と同様な作製方法にて、図１、
図８、図９のセンサ構造を有する窒素酸化物ガスセンサ
のサンプルを作製した。図１のセンササンプルはセンサ
部のみの構造体でヒータ(15)を取り付けないため、電気
炉中にサンプルをセットしてセンサを加熱しながら感度
測定を行った。図８と図９のセンササンプルは、設置さ
れた自己加熱ヒータで加熱した。外側電極(7)と内側電
極(8)間のジルコニアのバルクインピーダンスを測定し
ヒータ電圧にフィードバックをかけて温度を制御し、全
サンプルのセンサ温度を６００℃に保持した。酸素０.
４%、残部は窒素ガスからなるＮＯガス１５０ppm、酸素
０.４%、残部は窒素ガスからなるＮＯ2ガス１５０ppm、
及び酸素０.４%、残部は窒素ガスからなるＮＯガス１５
０ppmにＣ3Ｈ6ガス５００ppmを添加した測定ガスを用意
し、各検知出力を測定した。測定結果を表４に示す。表
４から、自己加熱ヒータのセンサ構造、特にセンサ構造
体(1a)の両面にヒータ(15)を設置したサンプルでは、ガ
ス検知室(6)の各電極が安定した温度分布を有するた
め、非常に安定したセンサ出力が得られることが分か
る。また、良好な温度分布にも関わらず電気炉中のサン
プルの出力が若干低いのは、リード線(20, 21, 22)の絶
縁性が若干低下するためと考えられる。Example 7 In the same manufacturing method as in Example 1, FIGS.
Samples of the nitrogen oxide gas sensor having the sensor structures of FIGS. 8 and 9 were produced. Since the sensor sample of FIG. 1 was a structure having only a sensor portion and was not provided with a heater (15), the sensitivity was measured while setting the sample in an electric furnace and heating the sensor. 8 and 9 were heated by the installed self-heating heater. The bulk impedance of zirconia between the outer electrode (7) and the inner electrode (8) was measured, the temperature was controlled by applying feedback to the heater voltage, and the sensor temperature of all samples was maintained at 600 ° C. Oxygen 0.
4%, the remaining 150 ppm NO gas composed of nitrogen gas, 0.4% oxygen, the remaining 150 ppm NO 2 gas composed of nitrogen gas,
NO gas 15 consisting of 0.4% oxygen and the balance nitrogen gas
A measurement gas in which 500 ppm of C 3 H 6 gas was added to 0 ppm was prepared, and each detection output was measured. Table 4 shows the measurement results. From Table 4, it can be seen that in the sensor structure of the self-heating heater, particularly in the sample in which the heaters (15) are installed on both sides of the sensor structure (1a), since the electrodes of the gas detection chamber (6) have a stable temperature distribution, It can be seen that a stable sensor output can be obtained. In addition, the reason why the output of the sample in the electric furnace is slightly low despite good temperature distribution is considered to be that the insulation of the lead wires (20, 21, 22) is slightly lowered.
【００５２】[0052]
【表４】 [Table 4]
【００５３】[例８]図４のセンサ構造の内部空間(6b)
と、図５のガス検知室(6)には、酸化触媒を特定の状態
で形成した以外は、例１と同様な作製方法にて、図４及
び図５のセンサ構造を有するセンササンプルを作製し
た。積層前のジルコニアグリーンシートに触媒ペースト
をスクリーン印刷して塗布形成し、乾燥後、別のジルコ
ニアグリーンシートと積層圧着した。酸化物からなる触
媒は、その粉末と直接有機バインダと有機溶剤を混ぜる
か、更にジルコニア粉末を添加混合して混練器でペース
トとした。貴金属からなる触媒は、貴金属粉末とジルコ
ニア粉末又はアルミナ粉末を混合して、同様に混練器で
ペーストを作製した。触媒層を印刷しない図４のセンサ
構造及びアルミナペーストのみの図５のセンサ構造を同
時に比較のため作製した。[Example 8] Internal space (6b) of the sensor structure in FIG.
Then, in the gas detection chamber (6) of FIG. 5, a sensor sample having the sensor structure of FIGS. 4 and 5 was manufactured by the same manufacturing method as in Example 1 except that the oxidation catalyst was formed in a specific state. did. The catalyst paste was screen-printed and formed on the zirconia green sheet before lamination, dried, and laminated and pressed with another zirconia green sheet. The oxide catalyst was prepared by directly mixing the powder with an organic binder and an organic solvent, or adding and mixing zirconia powder to form a paste with a kneader. The noble metal catalyst was prepared by mixing a noble metal powder and a zirconia powder or an alumina powder and similarly producing a paste with a kneader. The sensor structure of FIG. 4 without printing the catalyst layer and the sensor structure of FIG. 5 with only the alumina paste were simultaneously manufactured for comparison.
【００５４】[0054]
【表５】 [Table 5]
【００５５】温度５５０℃に保持した電気炉中の石英管
内に得られたセンサを配置して、ガス感度特性を調べ
た。酸素４%、残部は窒素ガスからなるＮＯガス１５０p
pm、酸素４%、残部は窒素ガスからなるＮＯ2ガス１５０
ppm及び酸素４%、残部は窒素ガスからなるＮＯガス１５
０ppmにＣ3Ｈ6ガス２０００ppmを添加した測定ガスを用
意し、各検知出力を測定した。触媒層の密着性（剥離状
況）と共に図４の構造の測定結果を表５に示し、図５の
構造の測定結果を表６に示す。酸化触媒構造を付与する
ことはＣ3Ｈ6ガス等の干渉ガスによる影響の除去に大き
な効果があり、また、ジルコニア添加触媒は製造上密着
性に優れることがわかる。また、図５の構造の方が、Ｎ
Ｏxの総検出性能及び干渉ガスの影響が更に小さいこと
がわかる。The obtained sensor was placed in a quartz tube in an electric furnace maintained at a temperature of 550 ° C., and gas sensitivity characteristics were examined. Oxygen 4%, the rest is NO gas consisting of nitrogen gas 150p
pm, oxygen 4%, balance of nitrogen gas NO 2 gas 150
ppm and oxygen 4%, balance NO gas consisting of nitrogen gas 15
A measurement gas in which 2000 ppm of C 3 H 6 gas was added to 0 ppm was prepared, and each detection output was measured. The measurement results of the structure of FIG. 4 are shown in Table 5 together with the adhesion (peeling state) of the catalyst layer, and the measurement results of the structure of FIG. 5 are shown in Table 6. It can be seen that the provision of the oxidation catalyst structure has a great effect on removing the influence of an interference gas such as C 3 H 6 gas, and that the zirconia-added catalyst has excellent adhesion in production. Further, the structure of FIG.
It can be seen that the total detection performance of Ox and the influence of the interference gas are even smaller.
【００５６】[0056]
【表６】 [Table 6]
【００５７】[0057]
【発明の効果】本発明による窒素酸化物ガスセンサで
は、外側電極、内側電極及び検知電極の３個の電極によ
り酸素のポンピングを行うと同時に測定ガス中の総ＮＯ
x濃度を検知することができるので、センサ機能及び検
知精度を低下せずに、従来のセンサ構成に比して構成さ
れる電極数、リード線数を大幅に減少することができ、
構造を簡素化することができる。According to the nitrogen oxide gas sensor of the present invention, oxygen is pumped by the three electrodes of the outer electrode, the inner electrode, and the detection electrode, and at the same time, the total NO in the measurement gas is increased.
Since x concentration can be detected, the number of electrodes and the number of lead wires can be significantly reduced as compared with the conventional sensor configuration without lowering the sensor function and detection accuracy,
The structure can be simplified.
【図１】 本発明による窒素酸化物ガスセンサの第１の
実施の形態を示す断面図FIG. 1 is a sectional view showing a first embodiment of a nitrogen oxide gas sensor according to the present invention.
【図２】 本発明による窒素酸化物ガスセンサの第２の
実施の形態を示す断面図FIG. 2 is a sectional view showing a second embodiment of the nitrogen oxide gas sensor according to the present invention.
【図３】 本発明による窒素酸化物ガスセンサの第３の
実施の形態を示す断面図FIG. 3 is a sectional view showing a third embodiment of the nitrogen oxide gas sensor according to the present invention.
【図４】 本発明による窒素酸化物ガスセンサの第４の
実施の形態を示す断面図FIG. 4 is a sectional view showing a nitrogen oxide gas sensor according to a fourth embodiment of the present invention.
【図５】 本発明による窒素酸化物ガスセンサの第５の
実施の形態を示す断面図FIG. 5 is a sectional view showing a nitrogen oxide gas sensor according to a fifth embodiment of the present invention.
【図６】 本発明による窒素酸化物ガスセンサの第６の
実施の形態を示す断面図FIG. 6 is a cross-sectional view showing a sixth embodiment of the nitrogen oxide gas sensor according to the present invention.
【図７】 本発明による窒素酸化物ガスセンサの第７の
実施の形態を示す断面図FIG. 7 is a sectional view showing a seventh embodiment of the nitrogen oxide gas sensor according to the present invention.
【図８】 本発明による窒素酸化物ガスセンサの第８の
実施の形態を示す断面図FIG. 8 is a sectional view showing an eighth embodiment of the nitrogen oxide gas sensor according to the present invention.
【図９】 本発明による窒素酸化物ガスセンサの第９の
実施の形態を示す断面図FIG. 9 is a sectional view showing a ninth embodiment of the nitrogen oxide gas sensor according to the present invention.
【図１０】 酸素ポンプの電流特性を示すグラフFIG. 10 is a graph showing current characteristics of an oxygen pump.
【図１１】 ＮＯx出力特性を示すグラフFIG. 11 is a graph showing NOx output characteristics.
【図１２】 酸素濃度変動に対するＮＯx出力特性を示
すグラフFIG. 12 is a graph showing NOx output characteristics with respect to oxygen concentration fluctuations.
【図１３】 内側電極の面積率とＮＯx出力特性との関
係を示すグラフFIG. 13 is a graph showing a relationship between an area ratio of an inner electrode and NOx output characteristics.
【図１４】 ガス導入口のガス拡散抵抗とガス検知室内
の酸素濃度との関係を示すグラフFIG. 14 is a graph showing the relationship between the gas diffusion resistance of the gas inlet and the oxygen concentration in the gas detection chamber.
【図１５】 従来の混成電位型ＮＯxセンサの断面図FIG. 15 is a cross-sectional view of a conventional mixed potential type NOx sensor.
(1)・・窒素酸化物ガスセンサ、 (1a)・・センサ構造
体、 (2)・・酸素イオン透過層、 (3)・・上壁、
(5)・・ダクト、 (6)・・ガス検知室、 (7)・・外側
電極、 (8)・・内側電極、 (9)・・検知電極、 (10)
・・底壁、 (13)・・開口部、 (14)・・付加電極、
(15)・・ヒータ基板、(1) ・ ・ Nitrogen oxide gas sensor, (1a) ・ ・ Sensor structure, (2) ・ ・ Oxygen ion permeable layer, (3) ・ ・ Top wall,
(5) ... duct, (6) ... gas detection chamber, (7) ... outer electrode, (8) ... inner electrode, (9) ... detection electrode, (10)
..Bottom walls, (13) .Openings, (14) .Additional electrodes,
(15) ・ ・ Heater substrate,
フロントページの続き (72)発明者 高 云智 埼玉県熊谷市末広四丁目14番１号 株式会 社リケン熊谷事業所内 Ｆターム(参考） 2G004 BB04 BD15 BE22 BE27 BK06 BL08 BM04 Continuation of the front page (72) Inventor Takashi Unchi 4-14-1, Suehiro, Kumagaya-shi, Saitama F-term (reference) in Riken Kumagaya Office 2G004 BB04 BD15 BE22 BE27 BK06 BL08 BM04
Claims (17)
より形成された酸素イオン透過層と、測定ガス雰囲気に
通ずるガス導入口が設けられたガス検知室と、酸素イオ
ン透過層と同一のイオン伝導体により連続しているガス
検知室内の底壁と、酸素イオン透過層を介してガス検知
室の反対側に形成されかつ大気に通じるダクトと、ダク
ト内で酸素イオン透過層に形成された酸素に活性な外側
電極と、ガス検知室内で酸素イオン透過層に形成されか
つ酸素とＮＯxに活性な内側電極と、内側電極と対面し
てガス検知室内の底壁に設置されかつ酸素及びＮＯxに
対して活性な検知電極とを備え、 カソード電極である外側電極及びアノード電極である内
側電極間に電圧を印加して、酸素イオン透過層を介して
ダクトからガス検知室内に供給される酸素により測定ガ
ス中に含まれるＮＯxガス中のＮＯを酸化させてＮＯ2の
単一ガスとし又はガス検知室内の還元性ガスを酸化させ
て、 検知電極と外側電極との間に生じる電位差を測定して、
測定ガス中の総ＮＯx濃度を検知することを特徴とする
窒素酸化物ガスセンサ。1. An oxygen ion permeable layer formed of a solid electrolyte having oxygen ion conductivity, a gas detection chamber provided with a gas inlet communicating with a measurement gas atmosphere, and an ion conductor identical to the oxygen ion permeable layer. The bottom wall in the gas detection chamber that is continuous with the air, a duct formed on the opposite side of the gas detection chamber through the oxygen ion permeable layer and communicating with the atmosphere, and active in the oxygen formed in the oxygen ion permeable layer in the duct An outer electrode, an inner electrode formed in the oxygen ion permeable layer in the gas detection chamber and active on oxygen and NOx, and installed on the bottom wall in the gas detection chamber facing the inner electrode and active on oxygen and NOx A voltage between the outer electrode, which is a cathode electrode, and the inner electrode, which is an anode electrode, so that oxygen supplied from the duct into the gas detection chamber through the oxygen ion permeable layer is provided. Was oxidized to NO of NOx in the gas is oxidized into a single gas NO 2 or gas detection chamber of the reducing gas contained more measurement gas by measuring the potential difference between the sensing electrode and the outer electrode hand,
A nitrogen oxide gas sensor for detecting a total NOx concentration in a measurement gas.
を流して、測定ガス中の総ＮＯx濃度を検知する請求項
１に記載の窒素酸化物ガスセンサ。2. The nitrogen oxide gas sensor according to claim 1, wherein a constant current is applied between the outer electrode and the inner electrode to detect a total NOx concentration in the measurement gas.
を０.１vol%以上に維持するガス拡散抵抗を有する請求
項１又は２に記載の窒素酸化物ガスセンサ。3. The nitrogen oxide gas sensor according to claim 1, wherein the gas inlet has a gas diffusion resistance for maintaining the oxygen concentration in the gas detection chamber at 0.1 vol% or more.
よりガス検知室内の酸素濃度を０.１vol%以上に維持す
る請求項１〜３のいずれか１項に記載の窒素酸化物ガス
センサ。4. The nitrogen oxide gas sensor according to claim 1, wherein the oxygen concentration in the gas detection chamber is maintained at 0.1 vol% or more by a porous body disposed inside the gas detection chamber.
ち、検知電極と直接対向する面はＮＯxに対して活性で
あり、検知電極と直接対向しない面はＮＯxに対して不
活性でありかつ酸素に対して活性である請求項１〜４の
いずれか１項に記載の窒素酸化物ガスセンサ。5. The surface of the inner electrode which is active against oxygen and NOx, the surface directly facing the detection electrode is active against NOx, and the surface not directly facing the detection electrode is inert against NOx. The nitrogen oxide gas sensor according to any one of claims 1 to 4, which is active for oxygen.
の内側電極設置面の面積に対する内側電極の占有比率は
４０%以上でありかつ酸素イオン透過層に対向する検知
電極の面積は内側電極の面積より小さい請求項１〜５の
いずれか１項に記載の窒素酸化物ガスセンサ。6. The occupation ratio of the inner electrode to the area of the inner electrode installation surface of the gas detection chamber facing the oxygen ion permeable layer is 40% or more, and the area of the detection electrode facing the oxygen ion permeable layer is equal to that of the inner electrode. The nitrogen oxide gas sensor according to any one of claims 1 to 5, which is smaller than the area.
導入口側から測定ガスの侵入方向の後方部に検知電極を
配置した請求項１〜６のいずれか１項に記載の窒素酸化
物ガスセンサ。7. The nitrogen oxide gas sensor according to claim 1, wherein a detection electrode is disposed in a gas detection chamber in which the inner electrode is installed, at a rear portion of the gas introduction port from a gas inlet side in a direction in which the measurement gas enters. .
れに連絡するガス検知室との間にガス拡散抵抗を制御す
る内部ガス通路又は内部ガス空間が形成された請求項１
〜７のいずれか１項に記載の窒素酸化物ガスセンサ。8. An internal gas passage or an internal gas space for controlling a gas diffusion resistance is formed between a gas inlet communicating with a measurement gas atmosphere and a gas detection chamber connected thereto.
The nitrogen oxide gas sensor according to any one of claims 1 to 7.
知室のいずれかに酸化触媒層、酸化触媒体又は酸化触媒
担持体を配置した請求項８に記載の窒素酸化物ガスセン
サ。9. The nitrogen oxide gas sensor according to claim 8, wherein an oxidation catalyst layer, an oxidation catalyst, or an oxidation catalyst carrier is disposed in any one of the internal gas passage, the internal gas space, and the gas detection chamber.
2Ｏ4、ＦｅＣｒ2Ｏ4、Ｃｒ2Ｏ3から選択されたクロム酸
化物を主成分とした材料又はＰｔ−Ｒｈ合金、Ｉｒ−Ｒ
ｈ合金、ＰｔとＲｈ酸化物との混相からなる電極である
請求項１〜９のいずれか１項に記載の窒素酸化物ガスセ
ンサ。10. The detecting electrode is made of NiCr 2 O 4 , MgCr.
A material mainly composed of chromium oxide selected from 2 O 4 , FeCr 2 O 4 , and Cr 2 O 3, a Pt-Rh alloy, Ir-R
The nitrogen oxide gas sensor according to any one of claims 1 to 9, wherein the electrode is an electrode made of a h-alloy, a mixed phase of Pt and Rh oxide.
−Ｒｈ合金、Ｉｒ−Ｒｈ合金、Ｐｔ−Ｒｕ合金の少なく
とも一つを主成分とする層からなる請求項１に記載の窒
素酸化物ガスセンサ。11. The surface of the inner electrode that is active on NOx is Pt.
The nitrogen oxide gas sensor according to claim 1, comprising a layer containing at least one of a -Rh alloy, an Ir-Rh alloy, and a Pt-Ru alloy as a main component.
加電極が、酸素イオン透過層と同一のイオン伝導体によ
り連続している底壁の測定ガス雰囲気中に直接曝される
底壁の裏面又はガス導入口に連絡するガス検知室内の底
壁の表面に固定され、付加電極と外側電極との間の酸素
濃度差に起因する起電力を測定して測定ガス中又は検知
ガス中の酸素濃度を検知する請求項１に記載の窒素酸化
物ガスセンサ。12. The back surface of the bottom wall, wherein the additional electrode active on oxygen and inert on NOx is directly exposed to the measurement gas atmosphere on the bottom wall which is continuous by the same ion conductor as the oxygen ion permeable layer. Alternatively, the oxygen concentration in the measurement gas or the detection gas is measured by measuring the electromotive force caused by the oxygen concentration difference between the additional electrode and the outer electrode, which is fixed to the surface of the bottom wall in the gas detection chamber connected to the gas inlet. The nitrogen oxide gas sensor according to claim 1, wherein the sensor detects a nitrogen oxide gas.
極との間の起電力を検出して、検知電極と外側電極との
間に生じる電位差出力を補正し、測定雰囲気中の総ＮＯ
x濃度を検知する請求項１２に記載の窒素酸化物ガスセ
ンサ。13. An electromotive force between the outer electrode and the additional electrode is detected based on the oxygen concentration difference, and a potential difference output generated between the detection electrode and the outer electrode is corrected, so that the total NO in the measurement atmosphere is corrected.
13. The nitrogen oxide gas sensor according to claim 12, which detects x concentration.
印加したときに、酸素イオンが酸素イオン透過層を通じ
てダクトからガス検知室に流れ、ダクトは酸素導入に対
するガス拡散抵抗を付与して、外側電極と内側電極間に
流れる酸素イオン電流が限界電流を生じたガス拡散律速
状態においてＮＯx濃度を検知する請求項１又は１２に
記載の窒素酸化物ガスセンサ。14. When a predetermined voltage is applied between the outer electrode and the inner electrode, oxygen ions flow from the duct to the gas detection chamber through the oxygen ion permeable layer, and the duct imparts gas diffusion resistance to oxygen introduction, The nitrogen oxide gas sensor according to claim 1 or 12, wherein the NOx concentration is detected in a gas diffusion controlled state in which an oxygen ion current flowing between the outer electrode and the inner electrode has generated a limiting current.
タ基板とが一体に形成された請求項１又は１２に記載の
窒素酸化物ガスセンサ。15. The nitrogen oxide gas sensor according to claim 1, wherein the bottom wall or the upper wall and the heater substrate in which the heater is embedded are formed integrally.
タ基板とが一体に形成されかつ一方のヒータのリードが
並列に接続され、単一電源により同時に駆動される請求
項１又は１２に記載の窒素酸化物ガスセンサ。16. The heater according to claim 1, wherein the bottom wall and the upper wall and the heater substrate having the heater embedded therein are integrally formed, the leads of one of the heaters are connected in parallel, and are driven simultaneously by a single power supply. Nitrogen oxide gas sensor.
同時に印加し、外側電極と内側電極間に存在する固体電
解質体のインピーダンスを測定し、これをもって温度セ
ンサとなし、その出力をヒータ制御回路にフィードバッ
クすることにより、前記温度センサの温度制御を行う請
求項１５又は１６に記載の窒素酸化物ガスセンサ。17. Simultaneously applying an AC voltage between the outer electrode and the inner electrode, measuring the impedance of the solid electrolyte body existing between the outer electrode and the inner electrode, forming a temperature sensor, and controlling the output with a heater 17. The nitrogen oxide gas sensor according to claim 15, wherein the temperature of the temperature sensor is controlled by feeding back to a circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11217789A JP2001041927A (en) | 1999-07-30 | 1999-07-30 | Nitrogen oxide gas sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11217789A JP2001041927A (en) | 1999-07-30 | 1999-07-30 | Nitrogen oxide gas sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001041927A true JP2001041927A (en) | 2001-02-16 |
Family
ID=16709760
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11217789A Withdrawn JP2001041927A (en) | 1999-07-30 | 1999-07-30 | Nitrogen oxide gas sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001041927A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7316767B2 (en) | 2002-08-30 | 2008-01-08 | Denso Corporation | Gas sensing element |
| WO2018030369A1 (en) * | 2016-08-09 | 2018-02-15 | 日本碍子株式会社 | Gas sensor |
| WO2020100644A1 (en) * | 2018-11-15 | 2020-05-22 | 株式会社デンソー | Gas sensor |
| WO2021059758A1 (en) * | 2019-09-23 | 2021-04-01 | 株式会社デンソー | Gas sensor |
-
1999
- 1999-07-30 JP JP11217789A patent/JP2001041927A/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7316767B2 (en) | 2002-08-30 | 2008-01-08 | Denso Corporation | Gas sensing element |
| WO2018030369A1 (en) * | 2016-08-09 | 2018-02-15 | 日本碍子株式会社 | Gas sensor |
| CN109564184A (en) * | 2016-08-09 | 2019-04-02 | 日本碍子株式会社 | Gas sensor |
| JPWO2018030369A1 (en) * | 2016-08-09 | 2019-06-13 | 日本碍子株式会社 | Gas sensor |
| US10845327B2 (en) | 2016-08-09 | 2020-11-24 | Ngk Insulators, Ltd. | Gas sensor |
| CN109564184B (en) * | 2016-08-09 | 2021-05-14 | 日本碍子株式会社 | Gas sensor |
| WO2020100644A1 (en) * | 2018-11-15 | 2020-05-22 | 株式会社デンソー | Gas sensor |
| WO2021059758A1 (en) * | 2019-09-23 | 2021-04-01 | 株式会社デンソー | Gas sensor |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6773565B2 (en) | NOx sensor | |
| KR101851281B1 (en) | Ammonia sensor | |
| JP3128114B2 (en) | Nitrogen oxide detector | |
| JPH11153578A (en) | Gas sensor, gas sensor system using the same and production of gas sensor | |
| JPH11201942A (en) | Nitrogen oxide sensor | |
| JP3855771B2 (en) | Porous electrode, electrochemical element including the same, gas concentration detection sensor, oxygen partial pressure control method, and combustible gas detection method | |
| JP3587290B2 (en) | NOx gas sensor | |
| JPH11166913A (en) | Gas sensor | |
| JP2002243692A (en) | Nitrogen oxide gas sensor | |
| JP3195758B2 (en) | Nitrogen oxide sensor | |
| JP2006133039A (en) | Nitrogen oxide sensor | |
| JP2002195978A (en) | Gas detector element and gas sensing device using it | |
| JPH1172476A (en) | Nitrogen oxide gas sensor | |
| JP2003185625A (en) | Gas detecting element and gas detecting apparatus using the same | |
| JP4153238B2 (en) | Electrochemical oxygen pump cell and nitrogen oxide detector using the same | |
| JP2001041927A (en) | Nitrogen oxide gas sensor | |
| JP3556790B2 (en) | Exhaust gas sensor and exhaust gas sensor system | |
| JP3943262B2 (en) | NOx gas concentration measuring apparatus and NOx gas concentration measuring method | |
| JP2002005883A (en) | Nitrogen oxide gas sensor | |
| JP4003879B2 (en) | Method for manufacturing gas sensor element and gas sensor element | |
| JP2002236107A (en) | Gas detecting element and gas detector using the same | |
| JP2000121604A (en) | Gas sensor | |
| JP4213939B2 (en) | Gas detector | |
| JP2001083117A (en) | Nitrogen oxide gas sensor | |
| JP2001221772A (en) | Electrochemical sensor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060728 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20090303 |
|
| A761 | Written withdrawal of application |
Free format text: JAPANESE INTERMEDIATE CODE: A761 Effective date: 20090609 |