JP4171803B2 - Oxygen sensor using oxide semiconductor - Google Patents

Oxygen sensor using oxide semiconductor Download PDF

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JP4171803B2
JP4171803B2 JP2003270843A JP2003270843A JP4171803B2 JP 4171803 B2 JP4171803 B2 JP 4171803B2 JP 2003270843 A JP2003270843 A JP 2003270843A JP 2003270843 A JP2003270843 A JP 2003270843A JP 4171803 B2 JP4171803 B2 JP 4171803B2
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oxide semiconductor
oxygen sensor
gas detection
oxygen
oxide
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JP2005024513A (en
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伊豆　　典哉
村山　　宣光
申　　ウソク
一郎 松原
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National Institute of Advanced Industrial Science and Technology AIST
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Description

本発明は、雰囲気ガスの酸素分圧に応じて抵抗値が変化する酸化物半導体からなるガス
検出部分を有している酸素センサに関するものであり、更に詳しくは、排ガスの浄化率向
上や燃費向上のための、自動車等の排ガスの空燃比を制御するための空燃比フィードバッ
ク制御システムに使われる酸素分圧を測定する酸素センサに関するものである。ここで、
空燃比とは空気と燃料の比であり、酸素分圧と空燃比とは1 対１の関係が成り立つ。本発
明は、小型で構造が簡単な酸化物半導体を使った酸素センサの技術分野において、広範囲
の酸素分圧で感度が良好な酸化物半導体を使った酸素センサを提供すること、また、自動
車等の排ガス浄化用触媒の劣化を検知するための自動車等の排ガス触媒劣化検知システム
に使用される酸素センサを提供すること、更に、ボイラー等の燃焼効率最適化のための空
燃比フィードバック制御システムに使われる酸素センサを提供すること、を可能にするも
のとして有用である。 The present invention relates to an oxygen sensor having a gas detection portion made of an oxide semiconductor whose resistance value changes in accordance with the oxygen partial pressure of atmospheric gas. More specifically, the present invention relates to an improvement in exhaust gas purification rate and fuel efficiency. The present invention relates to an oxygen sensor for measuring an oxygen partial pressure used in an air-fuel ratio feedback control system for controlling an air-fuel ratio of exhaust gas from an automobile or the like. here,
The air / fuel ratio is the ratio of air to fuel, and the oxygen partial pressure and the air / fuel ratio have a one-to-one relationship. The present invention provides an oxygen sensor using an oxide semiconductor having a good sensitivity in a wide range of oxygen partial pressures in the technical field of an oxygen sensor using an oxide semiconductor having a small and simple structure. To provide an oxygen sensor for use in an exhaust gas catalyst deterioration detection system for automobiles, etc., to detect deterioration of exhaust gas purification catalysts, and to be used in an air-fuel ratio feedback control system for optimization of combustion efficiency of boilers, etc. It is useful as an enabling to provide an oxygen sensor.

従来、一般に、自動車用の酸素ガスセンサとしては、例えば、先行技術文献に記載され
ているように、主として、固体電解質のものが用いられてきた（例えば、特許文献１参照
）。このタイプのセンサは、基準極と測定極の酸素分圧の違いを起電力として測定するも
のであり、必ず基準極が必要であるため、構造が複雑であり、小型化が困難であるという
問題点があった。この問題点を克服するために、例えば、先行技術文献に記載されている
ような、基準極を必要としない抵抗型酸素ガスセンサが開発されている（特許文献２参照
）。この抵抗型酸素ガスセンサの測定原理を簡単に説明すると、まず、雰囲気の酸素分圧
が変化したときに、酸化物半導体の酸素空孔濃度が変化する。酸化物半導体の抵抗率ある
いは電気伝導度は、酸素空孔濃度と１対１の対応関係があり、酸素空孔濃度の変化に伴い
、酸化物半導体の抵抗率が変化する。そこで、その抵抗率を測定することにより、雰囲気
の酸素分圧を知ることができる。 Conventionally, in general, as an oxygen gas sensor for automobiles, for example, as described in the prior art document, a solid electrolyte has been mainly used (see, for example, Patent Document 1). This type of sensor measures the difference in oxygen partial pressure between the reference electrode and the measurement electrode as an electromotive force. Since the reference electrode is always required, the structure is complicated and it is difficult to reduce the size. There was a point. In order to overcome this problem, for example, a resistance oxygen gas sensor that does not require a reference electrode as described in the prior art document has been developed (see Patent Document 2). The measurement principle of this resistance oxygen gas sensor will be briefly described. First, when the oxygen partial pressure of the atmosphere changes, the oxygen vacancy concentration of the oxide semiconductor changes. The resistivity or electric conductivity of the oxide semiconductor has a one-to-one correspondence with the oxygen vacancy concentration, and the resistivity of the oxide semiconductor changes with a change in the oxygen vacancy concentration. Therefore, the oxygen partial pressure of the atmosphere can be known by measuring the resistivity.

酸化物半導体を使った酸素センサの場合、出力を電圧とするには、ガス検出材料である
酸化物半導体に直列に基準抵抗を接続し、それに一定電圧を負荷し、酸化物半導体あるい
は基準抵抗における電位差を出力として用いる。ここで、基準抵抗とは一定の値を持つ抵
抗を持つもの、あるいは、ガス検出材料の抵抗の温度依存性に類似し、酸素分圧依存性の
ない温度補償材料のことである。この回路図を図１に示す。一定電圧をＥ、ガス検出部分
である酸化物半導体の抵抗をＲg1、基準抵抗をＲs1とすると、Ｒg1、Ｒs1は、次のように
表記される。
Ｒg1＝ｒg1×ｅｘｐ（Ｅa,g1／ＲＴ）×Ｐ1/n1 （１）
Ｒs1＝ｒs1×ｅｘｐ（Ｅa,s1／ＲＴ） （２） In the case of an oxygen sensor using an oxide semiconductor, in order to set the output to a voltage, a reference resistor is connected in series with the oxide semiconductor that is a gas detection material, and a constant voltage is applied to the oxide semiconductor or the reference resistor. The potential difference is used as an output. Here, the reference resistance is a material having a certain value or a temperature compensation material that is similar to the temperature dependency of the resistance of the gas detection material and has no oxygen partial pressure dependency. This circuit diagram is shown in FIG. Assuming that the constant voltage is E, the resistance of the oxide semiconductor that is the gas detection portion is R g1 , and the reference resistance is R s1 , R g1 and R s1 are expressed as follows.
R g1 = r g1 × exp (E a, g1 / RT) × P 1 / n1 (1)
R s1 = r s1 × exp (E a, s1 / RT) (2)

ここで、ｒg1、及びｒs1は、それぞれガス検出材料、及び基準抵抗の固有の抵抗を示し
、Ｅa,g1、及びＥa,s1は、それぞれガス検出材料、及び基準抵抗の活性化エネルギーを示
す。Ｐは酸素分圧、ｎ1 はガス検出材料固有の値であり、酸化セリウムでは約６である。
基準抵抗が一定抵抗の場合、Ｅa,s1は０である。ここで、ガス検出材料、基準抵抗での電
位差をそれぞれＶg1、Ｖs1とすると、
Ｖg1＝Ｒg1／（Ｒs1＋Ｒg1）×Ｅ （３）
Ｖs1＝Ｒs1／（Ｒs1＋Ｒg1）×Ｅ （４）
となり、Ｖg1あるいはＶs1がセンサ出力である。この出力が酸素分圧の対数とほぼ直線関
係が得られるのはｎ1 ＝６の場合、せいぜい酸素分圧の１０桁ほどの範囲であり、それよ
り広範囲では、直線から大きくずれる。したがって、酸素分圧の１０桁ほどの範囲以外で
は、このような回路をもつ酸化物半導体を使った酸素センサでは測定できないという問題
点があった。 Here, r g1 and r s1 indicate the specific resistance of the gas detection material and the reference resistance, respectively, and E a, g1 and E a, s1 indicate the activation energy of the gas detection material and the reference resistance, respectively. Indicates. P is the oxygen partial pressure, n 1 is a value specific to the gas detection material, and is about 6 for cerium oxide.
When the reference resistance is a constant resistance, E a, s1 is zero. Here, if the potential difference between the gas detection material and the reference resistance is V g1 and V s1 , respectively,
V g1 = R g1 / (R s1 + R g1 ) × E (3)
V s1 = R s1 / (R s1 + R g1 ) × E (4)
V g1 or V s1 is the sensor output. When n 1 = 6, this output has a linear relationship with the logarithm of the oxygen partial pressure. When n 1 = 6, the oxygen partial pressure is in the range of about 10 digits at most. Therefore, there is a problem that measurement cannot be performed by an oxygen sensor using an oxide semiconductor having such a circuit, except in the range of about 10 digits of oxygen partial pressure.

特開昭５５−１３７３３４号公報JP-A-55-137334 特開昭６２−１７４６４４号公報JP 62-174644 A

このような状況の中で、本発明者らは、上記従来技術に鑑みて、酸素分圧の対数に対す
る出力の関係が従来のものより広範囲の酸素分圧において、ほぼ直線である出力を得るこ
とを目標として鋭意研究を重ねた結果、ガス検出材料に直列に基準抵抗を接続した回路を
複数個並列に接続し、それに一定電圧を負荷し、複数個の基準抵抗の電位差の和あるいは
複数個のガス検出材料の電位差の和をセンサ出力とすることにより所期の目的を達成し得
ることを見出し、本発明を完成するに至った。 Under such circumstances, in view of the above prior art, the present inventors obtain an output in which the relationship of the output with respect to the logarithm of the oxygen partial pressure is substantially linear in a wider range of oxygen partial pressures than the conventional one. As a result of intensive research with the goal of, a plurality of circuits in which a reference resistor is connected in series to a gas detection material are connected in parallel, a constant voltage is applied to the circuit, and the sum of potential differences of a plurality of reference resistors or a plurality of It has been found that the intended purpose can be achieved by using the sum of the potential differences of the gas detection materials as the sensor output, and the present invention has been completed.

本発明は、ガス検出材料に直列に基準抵抗を接続した回路を複数個並列に接続し、それ
に一定電圧を負荷し、複数個の基準抵抗の電位差の和あるいは複数個のガス検出材料の電
位差の和をセンサ出力とすることにより、酸素分圧の対数に対する出力の関係が従来のも
のより広範囲の酸素分圧において、ほぼ直線である出力が得られる酸化物半導体を使った
酸素センサを提供することを目的とするものである。更に、本発明は、燃焼機関の燃焼最
適化のための空燃比フィードバック制御システムに使われる酸素センサ装置を提供するこ
とを目的とするものである。 In the present invention, a plurality of circuits in which a reference resistor is connected in series to a gas detection material are connected in parallel, a constant voltage is loaded thereon, and a sum of potential differences of a plurality of reference resistors or a potential difference of a plurality of gas detection materials is calculated. To provide an oxygen sensor using an oxide semiconductor that can obtain a substantially linear output in a broader range of oxygen partial pressures than the conventional one, by using the sum as the sensor output. It is intended. It is another object of the present invention to provide an oxygen sensor device used in an air-fuel ratio feedback control system for combustion optimization of a combustion engine.

上記課題を解決するための本発明は、以下の技術的手段から構成される。
（１）酸化物半導体を使った酸素センサであって、
（ａ）ガス検出材料である酸化物半導体と基準抵抗とが直列に接続された回路を複数個並列に接続した並列回路を有する、
（ｂ）上記並列回路に一定電圧を負荷したときの、複数個の基準抵抗の電位差の和又は平均、あるいは複数個のガス検出材料の電位差の和又は平均をセンサ出力とする、
（ｃ）複数個のガス検出材料の抵抗値が、酸素分圧の増加に対して増加する関係を有する、
ことを特徴とした酸化物半導体を使った酸素センサ。
（２）複数個の基準抵抗の電位差の和又は平均、あるいは複数個のガス検出材料の電位差の和又は平均を求めるための電圧加算回路を有する、前記（１）記載の酸化物半導体を使った酸素センサ。
（３）電圧加算回路の出力である電圧を測定するための回路を有する、前記（２）記載の酸化物半導体を使った酸素センサ。
（４）一定電圧を負荷するための定電圧電源を有する、前記（１）から（３）のいずれかに記載の酸化物半導体を使った酸素センサ。
（５）ヒータを有する、前記（１）から（４）のいずれかに記載の酸化物半導体を使った酸素センサ。
（６）ガス検出材料である酸化物半導体が、酸化セリウム、酸化チタン、酸化ガリウムあるいは酸化スズ、又は、それらの酸化物を含む複合酸化物である、前記（１）から（５）のいずれかに記載の酸化物半導体を使った酸素センサ。
（７）基準抵抗が、抵抗値の温度依存性が酸化物半導体と類似し、かつ、抵抗値の酸素濃度依存性がない温度補償材である、前記（１）から（６）のいずれかに記載の酸化物半導体を使った酸素センサ。
（８）温度補償材が、酸素イオン伝導体である、前記（７）記載の酸化物半導体を使った酸素センサ。
（９）酸化物半導体の形状が厚膜である、前記（１）から（８）のいずれかに記載の酸化物半導体を使った酸素センサ。
（１０）前記（１）から（９）のいずれかに記載の酸化物半導体を使った酸素センサを構成要素として含むことを特徴とする酸素センサ装置。
（１１）前記（１）から（９）のいずれかに記載の酸化物半導体を使った酸素センサを構成要素として含むことを特徴とする燃焼機関の空燃比を制御するための空燃比フィードバック制御システム。
（１２）自動車等の排ガスの空燃比を制御する、前記（１１）記載の空燃比フィードバック制御システム。 The present invention for solving the above-described problems comprises the following technical means.
(1) An oxygen sensor using an oxide semiconductor,
(A) having a parallel circuit in which a plurality of circuits in which an oxide semiconductor that is a gas detection material and a reference resistor are connected in series are connected in parallel;
(B) The sensor output is the sum or average of potential differences of a plurality of reference resistors or the sum or average of potential differences of a plurality of gas detection materials when a constant voltage is applied to the parallel circuit.
(C) The resistance value of the plurality of gas detection materials has a relationship of increasing with respect to an increase in oxygen partial pressure.
An oxygen sensor that uses an oxide semiconductor.
(2) The oxide semiconductor according to the above (1), which includes a voltage addition circuit for obtaining the sum or average of potential differences of a plurality of reference resistors or the sum or average of potential differences of a plurality of gas detection materials. Oxygen sensor.
(3) The oxygen sensor using an oxide semiconductor according to (2), further including a circuit for measuring a voltage that is an output of the voltage adding circuit.
(4) An oxygen sensor using the oxide semiconductor according to any one of (1) to (3), having a constant voltage power source for loading a constant voltage.
(5) An oxygen sensor using the oxide semiconductor according to any one of (1) to (4), having a heater.
(6) Any of (1) to (5) above, wherein the oxide semiconductor that is the gas detection material is cerium oxide, titanium oxide, gallium oxide, tin oxide, or a complex oxide containing such an oxide. An oxygen sensor using the oxide semiconductor described in 1.
(7) The reference resistance is any one of (1) to (6), wherein the temperature dependency of the resistance value is similar to that of an oxide semiconductor and the resistance value does not depend on the oxygen concentration. An oxygen sensor using the oxide semiconductor described.
(8) The oxygen sensor using the oxide semiconductor according to (7), wherein the temperature compensation material is an oxygen ion conductor.
(9) An oxygen sensor using the oxide semiconductor according to any one of (1) to (8), wherein the oxide semiconductor is a thick film.
(10) An oxygen sensor device including an oxygen sensor using the oxide semiconductor according to any one of (1) to (9) as a constituent element.
(11) An air-fuel ratio feedback control system for controlling the air-fuel ratio of a combustion engine, comprising as a component an oxygen sensor using the oxide semiconductor according to any one of (1) to (9) .
(12) The air-fuel ratio feedback control system according to (11), which controls the air-fuel ratio of exhaust gas from an automobile or the like.

次に、本発明について更に詳細に説明する。
本発明は、ガス検出材料である酸化物半導体と基準抵抗が直列に接続された回路が複数
個並列に接続された並列回路を有し、その並列回路に一定電圧を負荷したときの、複数個
の基準抵抗の電位差の和又は平均、あるいは複数個のガス検出材料の電位差の和又は平均
をセンサ出力としたことを特徴とする酸化物半導体を使った酸素センサである。ガス検出
材料である酸化物半導体と基準抵抗が直列に接続された回路が複数個並列に接続され、そ
の並列回路に一定電圧を負荷したときの、複数個の基準抵抗の電位差の和又は平均を出力
とする酸化物半導体を使った酸素センサの回路を図２に示す。図２で、Ｒsnはｎ番目の基
準抵抗を、Ｒgnはｎ番目のガス検出材料を示す。一定電圧Ｅを負荷し、基準抵抗での電位
差をＶsnとすると、
Ｖsn＝Ｒsn／（Ｒsn＋Ｒgn）×Ｅ （５）
と表すことができる。センサ出力をＶoutputとすると、ＶoutputはＶsnの和又は平均 Next, the present invention will be described in more detail.
The present invention has a parallel circuit in which a plurality of circuits in which an oxide semiconductor, which is a gas detection material, and a reference resistor are connected in series are connected in parallel, and when a constant voltage is applied to the parallel circuit, the plurality The oxygen sensor using an oxide semiconductor is characterized in that the sensor output is the sum or average of the potential differences of the reference resistances, or the sum or average of the potential differences of a plurality of gas detection materials. The sum or average of the potential differences of a plurality of reference resistors when a plurality of circuits in which a gas detection material oxide semiconductor and a reference resistor are connected in series are connected in parallel and a constant voltage is applied to the parallel circuit. FIG. 2 shows a circuit of an oxygen sensor using an oxide semiconductor as an output. In FIG. 2, R sn represents the nth reference resistance, and R gn represents the nth gas detection material. When a constant voltage E is loaded and the potential difference at the reference resistance is V sn ,
V sn = R sn / (R sn + R gn ) × E (5)
It can be expressed as. If the sensor output is V output , V output is the sum or average of V sn

Figure 0004171803
Figure 0004171803

である。また、Ｒgnでの電位差をＶgnとすると、ＶoutputはＶgnの和又は平均の値 It is. Also, when a potential difference in R gn and V gn, V output is the sum or average value of V gn

Figure 0004171803
Figure 0004171803

を用いることも可能である。 It is also possible to use.

複数個の基準抵抗の電位差の和又は平均、あるいは複数個のガス検出材料の電位差の和
又は平均を求めるための回路に制限はないが、例えば、図３に示すような回路がある。こ
の回路では、 There is no limitation on the circuit for obtaining the sum or average of the potential differences of a plurality of reference resistors or the sum or average of the potential differences of a plurality of gas detection materials. For example, there is a circuit as shown in FIG. In this circuit,

Figure 0004171803
Figure 0004171803

となる。ここで、Ｒf ＝Ｒmk（ｋ＝１，２，・・・・，ｎ）ならば、電位差の和が得られ
、Ｒmk＝ｎＲf （ｋ＝１，２，・・・・，ｎ）ならば、電位差の平均が得られる。図３の
右側のオペアンプは接地から見て正の出力にするためのものであり、出力が接地から見て
負の電圧でも可能であれば省略できる。図３に示す回路は電圧加算アンプの原理的なもの
であり、現実の回路はもう少し複雑である。 It becomes. Here, if R f = R mk (k = 1, 2,..., N), the sum of potential differences is obtained, and R mk = nR f (k = 1, 2,..., N). ), The average of the potential difference is obtained. The operational amplifier on the right side of FIG. 3 is for a positive output when viewed from the ground, and even if the output is a negative voltage when viewed from the ground, it can be omitted if possible. The circuit shown in FIG. 3 is the principle of a voltage summing amplifier, and the actual circuit is a little more complicated.

ガス検出材料は測定したい雰囲気に保持しなければならないが、基準抵抗は測定したい
雰囲気に保持する必要はない。例えば、自動車のエンジンからの排ガスの酸素分圧を調べ
る場合、ガス検出材料は、排ガス中に保持しなければならないが、基準抵抗は、排ガス中
あるいは排ガスの外のどちらでもよい。ただし、基準抵抗が温度補償材料の場合、ガス検
出材料のすぐ近くにそれがあれば精度がよくなるので、排ガス中に保持したほうが良い。
ガス検出材料の酸化物半導体としては、好適には、例えば、酸化セリウム、酸化チタン
、酸化ガリウムなどが列挙できるが、これらに限定されない。また、基準抵抗としては、
固定の抵抗値を有する抵抗でも可能であるし、温度補償材料でも可能である。温度補償材
料としては、例えば、イオン伝導体、ガラスシールされた酸化物半導体などが挙げられる
が、これらに限定されない。また、ガス検出材料の形態は、バルク体、厚膜、薄膜など種
々の形態が可能であるが、厚膜、薄膜の場合、基板が必要となる。基板材料としては、絶
縁体である酸化アルミニウム、酸化マグネシウム、石英などが例示されるが、これらに制
限されるものではない。 The gas detection material must be kept in the atmosphere to be measured, but the reference resistance need not be kept in the atmosphere to be measured. For example, when the oxygen partial pressure of exhaust gas from an automobile engine is examined, the gas detection material must be held in the exhaust gas, but the reference resistance may be either in the exhaust gas or outside the exhaust gas. However, if the reference resistance is a temperature compensation material, the accuracy will be improved if it is in the immediate vicinity of the gas detection material, so it is better to keep it in the exhaust gas.
Preferable examples of the oxide semiconductor of the gas detection material include, but are not limited to, cerium oxide, titanium oxide, gallium oxide, and the like. In addition, as a reference resistance,
It can be a resistor having a fixed resistance value or a temperature compensation material. Examples of the temperature compensation material include, but are not limited to, ion conductors and glass-sealed oxide semiconductors. The gas detection material can be in various forms such as a bulk body, a thick film, and a thin film. In the case of a thick film and a thin film, a substrate is required. Examples of the substrate material include, but are not limited to, aluminum oxide, magnesium oxide, and quartz that are insulators.

基準抵抗についても、形態を限定しない。基準抵抗が固定の抵抗値を有するものの場合
、ガス検出材料に隣接して設置する必要がなく、設置場所は任意である。基準抵抗が温度
補償材料の場合、ガス検出材料と隣接して温度補償材料を設けることが好ましい。
ガス検出材料や温度補償材料には電極材料を使用することがあるが、電極材料としては
、Ｐｔ、Ａｕ、Ｐｄなどの貴金属及び導電性酸化物などが挙げられる。センサの作製方法
は任意である。
ヒータ付の酸化物半導体を使った酸素センサの場合、例えば、基板にセラミックヒータ
、シリコンマイクロヒータなどを取り付ける。ただし、ヒータの取り付け位置、ヒータの
形状、ヒータの特性については、特に限定するものではない。 The form of the reference resistance is not limited. When the reference resistance has a fixed resistance value, it is not necessary to install it adjacent to the gas detection material, and the installation location is arbitrary. When the reference resistance is a temperature compensation material, it is preferable to provide a temperature compensation material adjacent to the gas detection material.
An electrode material may be used for the gas detection material and the temperature compensation material, and examples of the electrode material include noble metals such as Pt, Au, and Pd, and conductive oxides. The method for producing the sensor is arbitrary.
In the case of an oxygen sensor using an oxide semiconductor with a heater, for example, a ceramic heater, a silicon micro heater, or the like is attached to the substrate. However, the attachment position of the heater, the shape of the heater, and the characteristics of the heater are not particularly limited.

本発明の酸化物半導体を使った酸素センサは、表示部を備えた酸素センサ装置に用いる
ことが可能である。この装置は、本発明の酸化物半導体を使った酸素センサと、出力であ
るＶoutputを酸素分圧に変換する回路と、その酸素分圧を表示する表示部とを基本的構成
要素として任意に設計することが可能である。
本発明に係る自動車用空燃比フィードバック制御システムは、例えば、本発明の酸化物
半導体を使った酸素センサと、エンジンに流入する空気の流量を測定する流量計と、エン
ジンに燃料を入れる燃料噴射器と、酸素センサや流量計からの信号を受け取り、計算を行
い、燃料噴射器の燃料噴射量を制御するコントロール回路とを基本的構成要素として含む
ものが例示されるが、これらに制限されない。 The oxygen sensor using the oxide semiconductor of the present invention can be used for an oxygen sensor device including a display portion. This apparatus has an oxygen sensor using an oxide semiconductor of the present invention, a circuit that converts V output as an output into an oxygen partial pressure, and a display unit that displays the oxygen partial pressure as basic components. It is possible to design.
An air-fuel ratio feedback control system for an automobile according to the present invention includes, for example, an oxygen sensor using the oxide semiconductor of the present invention, a flow meter for measuring the flow rate of air flowing into the engine, and a fuel injector for injecting fuel into the engine And a control circuit that receives a signal from an oxygen sensor or a flow meter, performs calculation, and controls a fuel injection amount of the fuel injector as basic components, but is not limited thereto.

また、本発明に係る燃焼機関の燃焼効率最適化のための空燃比フィードバック制御シス
テムは、例えば、本発明の酸化物半導体を使った酸素センサと、燃焼機関に流入する空気
の流量を測定する流量計と、燃焼機関内に入れる燃料を制御する燃料制御器と、酸素セン
サや流量計からの信号を受け取り、計算を行い、燃料制御器に出力信号を送る電子制御ユ
ニットとを基本的構成要素として含むものが例示されるが、これらに制限されない。
更に、本発明に係る自動車排ガス触媒劣化検知システムは、本発明の酸化物半導体を使
った酸素センサと、酸素センサからの信号を読み取り計算し触媒が劣化したかどうかを判
断する電子制御ユニットと、電子制御ユニットからの信号を受けとり、触媒が劣化したか
どうかを示す表示部とを基本的構成要素として含むものが例示されるが、これらに制限さ
れない。 The air-fuel ratio feedback control system for optimizing the combustion efficiency of the combustion engine according to the present invention includes, for example, an oxygen sensor using the oxide semiconductor of the present invention and a flow rate for measuring the flow rate of air flowing into the combustion engine. The basic components are a meter, a fuel controller that controls the fuel that enters the combustion engine, and an electronic control unit that receives signals from oxygen sensors and flow meters, performs calculations, and sends output signals to the fuel controller Although what is included is illustrated, it is not limited to these.
Furthermore, the automobile exhaust gas catalyst deterioration detection system according to the present invention includes an oxygen sensor using the oxide semiconductor of the present invention, an electronic control unit that reads and calculates a signal from the oxygen sensor and determines whether the catalyst has deteriorated, Although the thing which receives the signal from an electronic control unit and contains the display part which shows whether the catalyst deteriorated as a basic component is illustrated, it is not restrict | limited to these.

従来技術での酸素分圧と出力電圧の関係を計算により求め、図４に示す。回路図は図１
と同じである。また、センサは一定温度に保たれているとする。この場合、式（１）での
（Ｅa,g1／ＲＴ）の項は考えなくてよい。従って、ガス検出材料の抵抗を
Ｒg1＝ｒg1×Ｐ1/n1 （７）
とし、Ｐ: 酸素分圧（ａｔｍ）、ｒg1＝１（ＭΩ）、ｎ1 ＝６とした。また、基準抵抗を
Ｒs1＝２（ｋΩ）とし、
Ｖs1＝Ｒs1／（Ｒs1＋Ｒg1）×Ｅ （８）
より、出力を求めた。ここで、Ｅ＝１０（Ｖ）とした。図４から明らかのように、ｌｏｇ
（Ｐ／ａｔｍ）が−１１から−２１までは、ほぼ直線が得られたが、それ以外の範囲では
、この直線から多きくずれ、しかも傾きが小さくなった。 The relationship between oxygen partial pressure and output voltage in the prior art is obtained by calculation and shown in FIG. The circuit diagram is shown in FIG.
Is the same. It is assumed that the sensor is kept at a constant temperature. In this case, the term (E a, g1 / RT) in the equation (1) need not be considered. Therefore, the resistance of the gas detection material is R g1 = r g1 × P 1 / n1 (7)
And P: oxygen partial pressure (atm), r g1 = 1 (MΩ), and n 1 = 6. The reference resistance is R s1 = 2 (kΩ),
V s1 = R s1 / (R s1 + R g1 ) × E (8)
The output was obtained. Here, E = 10 (V). As is clear from FIG.
When (P / atm) is from -11 to -21, a substantially straight line is obtained, but in other ranges, the line is greatly deviated from this straight line, and the inclination is small.

次に、本発明での計算例を図５に示す。回路図は図２に示す場合であり、ここで、ガス
検出材料を２つ用いた。抵抗値は
Ｒg1＝ｒg1×Ｐ1/n1 （９）
Ｒg2＝ｒg2×Ｐ1/n2 （１０）
とし、Ｐ：酸素分圧（ａｔｍ）、ｒg1＝ｒg2＝１（ＭΩ）、ｎ1 ＝ｎ2 ＝６とした。また
、基準抵抗をそれぞれＲs1＝２（ｋΩ）、Ｒs2＝２００（ｋΩ）とし、 Ｖs1＝Ｒs1／（
Ｒs1＋Ｒg1）×Ｅ （１１）
Ｖs2＝Ｒs2／（Ｒs2＋Ｒg2）×Ｅ （１２）
Ｖoutput＝（Ｖs1＋Ｖs2）／２ （１３）
より、出力を求めた。ここで、Ｅ＝１０（Ｖ）とした。図５から明らかなように、ｌｏｇ
（Ｐ／ａｔｍ）が０から−２１までほぼ直線が得られ、広範囲で測定できることがわかる
。もっと広範囲の酸素分圧を測定したい場合は、更にガス検出材料と基準抵抗を直列につ
ないだ回路を図２に示すように接続し、ガス検出材料と基準抵抗の抵抗値を最適化すれば
、測定可能となる。以上の結果は、センサを一定温度に保持した場合である。 Next, a calculation example according to the present invention is shown in FIG. The circuit diagram is the case shown in FIG. 2, where two gas detection materials were used. The resistance value is R g1 = r g1 × P 1 / n1 (9)
R g2 = r g2 × P 1 / n2 (10)
And P: oxygen partial pressure (atm), r g1 = r g2 = 1 (MΩ), and n 1 = n 2 = 6. Reference resistances are R s1 = 2 (kΩ) and R s2 = 200 (kΩ), respectively, and V s1 = R s1 / (
R s1 + R g1 ) × E (11)
V s2 = R s2 / (R s2 + R g2 ) × E (12)
V output = (V s1 + V s2 ) / 2 (13)
The output was obtained. Here, E = 10 (V). As is clear from FIG.
It can be seen that a substantially straight line is obtained from (P / atm) from 0 to -21, and measurement is possible over a wide range. If you want to measure a wider range of oxygen partial pressure, connect a circuit that connects a gas detection material and a reference resistance in series as shown in Fig. 2, and optimize the resistance value of the gas detection material and the reference resistance. It becomes possible to measure. The above results are obtained when the sensor is held at a constant temperature.

次に、センサを一定温度でなく、温度が変動する雰囲気で使用した場合を考える。ガス
検出材料の抵抗Ｒg1とＲg2の活性化エネルギーをＥa,g1とＥa,g2とすると、
Ｒg1＝ｒg1×ｅｘｐ（Ｅa,g1／ＲＴ）×Ｐ1/n1 （１４）
Ｒg2＝ｒg2×ｅｘｐ（Ｅa,g2／ＲＴ）×Ｐ1/n2 （１５）
となる。ここで、基準抵抗Ｒs1とＲs2も、それぞれＲg1やＲg2と同じ活性化エネルギーを
持つとすると、
Ｒs1＝ｒs1×（Ｅa,g1／ＲＴ） （１６）
Ｒs2＝ｒs2×（Ｅa,g2／ＲＴ） （１７）
となる。したがって、Ｒg1、Ｒg2、Ｒs1、Ｒs2を式（１１）と（１２）に代入して計算す
ると、
Ｖs1＝ｒs1／（ｒs1＋ｒg1×Ｐ1/n1）×Ｅ （１８）
Ｖs2＝ｒs2／（ｒs2＋ｒg2×Ｐ1/n2）×Ｅ （１９）
となり、式（１８）及び（１９）には温度の項が含まれない。つまり、Ｖs1及びＶs2は温
度依存性がないことになる。以上のように、基準抵抗がガス検出材料と同じ温度依存性で
あれば、センサの温度を一定に保たなくても出力は変動しない。 Next, consider a case where the sensor is used in an atmosphere where the temperature fluctuates instead of a constant temperature. If the activation energies of the resistances R g1 and R g2 of the gas detection material are E a, g1 and E a, g2 ,
R g1 = r g1 × exp (E a, g1 / RT) × P 1 / n1 (14)
R g2 = r g2 × exp (E a, g2 / RT) × P 1 / n2 (15)
It becomes. Here, if the reference resistors R s1 and R s2 also have the same activation energy as R g1 and R g2 , respectively,
R s1 = r s1 × (E a, g1 / RT) (16)
R s2 = r s2 × (E a, g2 / RT) (17)
It becomes. Therefore, substituting R g1 , R g2 , R s1 , and R s2 into equations (11) and (12) and calculating,
V s1 = r s1 / (r s1 + r g1 × P 1 / n1 ) × E (18)
V s2 = r s2 / (r s2 + r g2 × P 1 / n2 ) × E (19)
Thus, Equations (18) and (19) do not include a temperature term. That is, V s1 and V s2 have no temperature dependence. As described above, if the reference resistance is the same temperature dependency as that of the gas detection material, the output does not fluctuate even if the temperature of the sensor is not kept constant.

本発明は、ガス検出材料に直列に基準抵抗を接続した回路を複数個並列に接続した並列
回路を有し、それに一定電圧を負荷したときの、複数個の基準抵抗の電位差の和又は平均
あるいは複数個のガス検出材料の電位差の和又は平均をセンサ出力とすることを特徴とす
る酸素センサに係るものであり、本発明により、１）酸素分圧の対数に対する出力の関係
が従来のものより広範囲の酸素分圧において、ほぼ直線である出力が得られる酸化物半導
体を使った酸素センサが提供できる、２）燃焼機関の燃焼最適化のための空燃比フィード
バック制御システムに使われる酸素センサ装置を提供できる、３）λ＝１近傍で出力のギ
ャップがある、４）λ＞１あるいはλ＜１において、λの値を知ることができる、５）小
型で構造が簡単な酸素センサを提供できる、という格別の効果が奏される。 The present invention has a parallel circuit in which a plurality of circuits in which a reference resistance is connected in series to a gas detection material is connected in parallel, and when a constant voltage is applied thereto, the sum or average of the potential differences of the plurality of reference resistances or The present invention relates to an oxygen sensor characterized in that the sum or average of potential differences of a plurality of gas detection materials is used as a sensor output. According to the present invention, 1) the relationship of the output with respect to the logarithm of oxygen partial pressure is higher than the conventional one. It is possible to provide an oxygen sensor using an oxide semiconductor that can provide a substantially linear output over a wide range of oxygen partial pressures. 2) An oxygen sensor device used in an air-fuel ratio feedback control system for combustion optimization of a combustion engine 3) There is an output gap in the vicinity of λ = 1. 4) When λ> 1 or λ <1, the value of λ can be known. 5) A small and simple oxygen sensor is provided. Possible, special effect can be attained.

次に、実施例に基づいて本発明を具体的に説明するが、本発明は、以下の実施例によっ
て何ら限定されるものではない。 EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.

図６に示すようなガス検出材料の厚膜を作製した。作製方法を以下に示す。まず、Ｐｔ
ペーストをアルミナ基板上にスクリーン印刷法により印刷し、１２００℃で１ｈ焼成させ
、電極を作製した。次に、酸化セリウムのペーストを電極上にスクリーン印刷法により印
刷し、５００℃で５ｈの仮焼後、１１００℃で２ｈで焼成させ、センサ素子部を得た。こ
のセンサ素子部の図６の電極Ａ，Ｂ，Ｃがそれぞれ図７のＡ，Ｂ，Ｃとなるように回路を
作製した。素子部基準抵抗Ｒs1とＲs2はそれぞれ２００ｋΩと２ｋΩとした。また、一定
電圧Ｅは１０Ｖとした。ガス検出材料部分を８００℃に加熱し、酸素分圧を１０-17 から
１ａｔｍまで変化させ、Ｖs1とＶs2をそれぞれ求めた。その結果を図８に示す。また、Ｖ
s1とＶs2の平均も併せて示す。Ｖs1は、酸素分圧が１０-4から１ａｔｍまでは、傾きが大
きいが、１０-15 ａｔｍ以下では傾きがほとんどなかった。また、Ｖs2では逆に１０-4か
ら１ａｔｍまで、傾きはほとんどなく、１０-15 ａｔｍ以下では傾きが大きかった。この
ことから、Ｖs1、Ｖs2単独では酸素分圧の狭い範囲しか感度のいい部分はなかった。一方
、（Ｖs1＋Ｖs2）／２は１ａｔｍから１０-17 ａｔｍまで傾きが大きく、かつ広範囲で直
線関係が得られた。このことから、Ｖs1とＶs2の加算あるいは平均した値を出力とする酸
素センサは広範囲な酸素分圧を検出できることが確認できた。 A thick film of a gas detection material as shown in FIG. 6 was produced. A manufacturing method is shown below. First, Pt
The paste was printed on an alumina substrate by a screen printing method and baked at 1200 ° C. for 1 h to produce an electrode. Next, a paste of cerium oxide was printed on the electrode by a screen printing method, calcined at 500 ° C. for 5 h, and then baked at 1100 ° C. for 2 h to obtain a sensor element portion. A circuit was fabricated so that the electrodes A, B, and C in FIG. 6 of the sensor element portion were respectively A, B, and C in FIG. The element unit reference resistances R s1 and R s2 were 200 kΩ and 2 kΩ, respectively. The constant voltage E was 10V. The gas detection material portion was heated to 800 ° C., the oxygen partial pressure was changed from 10 −17 to 1 atm, and V s1 and V s2 were obtained. The result is shown in FIG. Also, V
The average of s1 and Vs2 is also shown. V s1 has a large inclination when the oxygen partial pressure is 10 −4 to 1 atm, but hardly has an inclination when the oxygen partial pressure is 10 −15 atm or less. On the contrary, in V s2 , there was almost no inclination from 10 −4 to 1 atm, and the inclination was large below 10 −15 atm. For this reason, V s1 and V s2 alone had only a sensitive part in a narrow range of oxygen partial pressure. On the other hand, (V s1 + V s2 ) / 2 had a large gradient from 1 atm to 10 −17 atm, and a linear relationship was obtained over a wide range. From this, it was confirmed that the oxygen sensor that outputs the sum or average of V s1 and V s2 can detect a wide range of oxygen partial pressures.

実施例１と同条件で作製したガス検出材を８５０℃に加熱し、図７の回路を用いて、実
施例１と同様にして測定した結果を図９に示す。Ｒs1とＲs2は実施例１と同条件のそれぞ
れ２００ｋΩと２ｋΩである。図９から明らかなように、温度を変えても広範囲な酸素分
圧を検出できることが確認できた。 FIG. 9 shows the results obtained by heating the gas detection material produced under the same conditions as in Example 1 to 850 ° C. and measuring in the same manner as in Example 1 using the circuit of FIG. R s1 and R s2 are 200 kΩ and 2 kΩ, respectively, under the same conditions as in the first embodiment. As is clear from FIG. 9, it was confirmed that a wide range of oxygen partial pressures could be detected even when the temperature was changed.

実施例１と同条件で作製したガス検出材料を８００℃に加熱し、図７の回路及びＶs1と
Ｖs2の電圧を平均するための電圧加算アンプを用いて、電圧加算アンプの出力をセンサ出
力Ｖoutputとして求めた。その結果を図１０に示す。図１０から明らかなように、広範囲
の酸素分圧でほぼ直線関係が得られた。このことから、本発明により、広範囲の酸素分圧
で感度が良好な酸化物半導体を使った酸素センサを作ることが可能であることが示された
。 The gas detection material produced under the same conditions as in Example 1 is heated to 800 ° C., and the output of the voltage addition amplifier is sensored using the circuit of FIG. 7 and the voltage addition amplifier for averaging the voltages of V s1 and V s2. The output V output was obtained. The result is shown in FIG. As is apparent from FIG. 10, a substantially linear relationship was obtained over a wide range of oxygen partial pressures. From this, it was shown that according to the present invention, it is possible to make an oxygen sensor using an oxide semiconductor with good sensitivity in a wide range of oxygen partial pressures.

メタンガスの燃焼反応から、空燃比λと酸素分圧Ｐの関係を求めた。なお、Ｒg1＝Ｒg2
＝１×Ｐ1/6 （ＭΩ）が成り立っている場合とした。Ｒs1＝２００（ｋΩ）、Ｒs2＝２（
ｋΩ）とした場合、式（１１）、（１２）、（１３）を使って計算すると空燃比と酸素セ
ンサの出力は図１１のようになる。この場合、λ＝１での出力の変化は大きいが、λ＞１
又はλ＜１の範囲では、λに対するセンサの出力の依存性は小さい。しかし、Ｒs1＝２（
ＭΩ）、Ｒs2＝１００（Ω）とした場合、λ＝１での出力の変化は少し小さくなるが、λ
＞１又はλ＜１の範囲では、λに対するセンサの出力の依存性は大きくなる。このように
、基準抵抗の大きさを最適化すれば、λ＞１又はλ＜１の範囲でもセンサのλに対する出
力の依存性を大きくすることは可能であり、λ＞１又はλ＜１の範囲において、λの値を
求めることが可能となることがわかる。 From the combustion reaction of methane gas, the relationship between the air-fuel ratio λ and the oxygen partial pressure P was determined. R g1 = R g2
= 1 × P 1/6 (MΩ). R s1 = 200 (kΩ), R s2 = 2 (
kΩ), the air-fuel ratio and the output of the oxygen sensor are as shown in FIG. 11 when calculated using the equations (11), (12), and (13). In this case, the output changes greatly at λ = 1, but λ> 1
In the range of λ <1, the dependence of the sensor output on λ is small. However, R s1 = 2 (
MΩ) and R s2 = 100 (Ω), the change in output at λ = 1 is slightly smaller, but λ
In the range of> 1 or λ <1, the dependence of the sensor output on λ increases. As described above, by optimizing the size of the reference resistance, it is possible to increase the output dependency on the λ of the sensor even in the range of λ> 1 or λ <1, and λ> 1 or λ <1. It can be seen that the value of λ can be obtained in the range.

以上詳述したように、本発明は、ガス検出材料に直列に基準抵抗を接続した回路を複数
個並列に接続した並列回路を有し、それに一定電圧を負荷したときの、複数個の基準抵抗
の電位差の和又は平均あるいは複数個のガス検出材料の電位差の和又は平均をセンサ出力
とすることを特徴とする酸素センサに係るものであり、本発明により、１）酸素分圧の対
数に対する出力の関係が従来のものより広範囲の酸素分圧において、ほぼ直線である出力
が得られる酸化物半導体を使った酸素センサが提供できる、２）燃焼機関の燃焼最適化の
ための空燃比フィードバック制御システムに使われる酸素センサ装置を提供できる、３）
λ＝１近傍で出力のギャップがある、４）λ＞１あるいはλ＜１において、λの値を知る
ことができる、５）小型で構造が簡単な酸素センサを提供できる。 As described above in detail, the present invention has a parallel circuit in which a plurality of circuits in which a reference resistor is connected in series to a gas detection material is connected in parallel, and a plurality of reference resistors when a constant voltage is applied thereto. According to the present invention, the present invention relates to an oxygen sensor characterized in that the sensor output is the sum or average of the potential differences of the gas or the sum or average of the potential differences of the plurality of gas detection materials. It is possible to provide an oxygen sensor using an oxide semiconductor that can provide an output that is almost linear over a wider range of oxygen partial pressures than the conventional one. 2) An air-fuel ratio feedback control system for combustion optimization of a combustion engine Can provide oxygen sensor device used in
There is an output gap in the vicinity of λ = 1. 4) When λ> 1 or λ <1, the value of λ can be known. 5) A small and simple oxygen sensor can be provided.

従来技術による酸化物半導体を使った酸素センサの回路図である。It is a circuit diagram of the oxygen sensor using the oxide semiconductor by a prior art. 本発明における、酸素センサの回路図であり、ガス検出材料である酸化物半導体と基準抵抗が直列に接続された回路が複数個並列に接続され、その並列回路に一定電圧を負荷したときの、複数個の基準抵抗の電位差の和又は平均を出力とする酸化物半導体を使った酸素センサの回路である。In the present invention, it is a circuit diagram of an oxygen sensor, and a plurality of circuits in which an oxide semiconductor that is a gas detection material and a reference resistor are connected in series are connected in parallel, and when a constant voltage is applied to the parallel circuit, This is an oxygen sensor circuit using an oxide semiconductor that outputs the sum or average of potential differences of a plurality of reference resistors. 複数個の基準抵抗の電位差の和又は平均、あるいは複数個のガス検出材料の電位差の和又は平均を求めるための回路の一例である。It is an example of the circuit for calculating | requiring the sum or average of the electrical potential difference of several reference resistance, or the sum or average of the electrical potential difference of several gas detection material. 従来技術による酸素分圧と出力電圧の関係を計算により求めた結果である。図１に示す回路図において、ｒg1＝１（ＭΩ）、ｎ1 ＝６、Ｒs1＝２（ｋΩ）、Ｅ＝１０（Ｖ）ととし、式（８）よりＶs1を求めた。It is the result of having calculated | required the relationship between the oxygen partial pressure and output voltage by a prior art by calculation. In the circuit diagram shown in FIG. 1, r g1 = 1 (MΩ), n 1 = 6, R s1 = 2 (kΩ), and E = 10 (V), and V s1 was obtained from Equation (8). 本発明での酸素分圧と出力電圧の関係を計算により求めた結果である。図２に示す回路図においてガス検出材料を２つ用いて、Ｐ： 酸素分圧（ａｔｍ）、ｒg1＝ｒg2＝１（ＭΩ）、ｎ1 ＝ｎ2 ＝６、Ｒs1＝２（ｋΩ）、Ｒs2＝２００（ｋΩ）、Ｅ＝１０（Ｖ）として、式（１１），（１２），（１３）を用いてＶoutputを求めた。It is the result of calculating | requiring the relationship between the oxygen partial pressure and output voltage in this invention by calculation. In the circuit diagram shown in FIG. 2, using two gas detection materials, P: oxygen partial pressure (atm), r g1 = r g2 = 1 (MΩ), n 1 = n 2 = 6, R s1 = 2 (kΩ) ), R s2 = 200 (kΩ), E = 10 (V), and V output was obtained using equations (11), (12), and (13). ガス検出材料の配置の一例である。Ａ、Ｂ、Ｃは電極であり、図７のＡ、Ｂ、Ｃとそれぞれ対応する。１：基板、２：Ｐｔ電極、３：ガス検出材料（ＣｅＯ2 ）の厚膜である。It is an example of arrangement | positioning of a gas detection material. A, B, and C are electrodes, and correspond to A, B, and C in FIG. 1: substrate, 2: Pt electrode, 3: thick film of gas detection material (CeO 2 ). 実施例１で用いた回路図を示す。Ａ、Ｂ、Ｃは電極であり、図６のＡ、Ｂ、Ｃとそれぞれ対応する。The circuit diagram used in Example 1 is shown. A, B, and C are electrodes, and correspond to A, B, and C in FIG. ガス検出材料部分を８００℃に加熱した場合の、抵抗Ｒs1、Ｒs2での電位差Ｖs1、Ｖs2及びＶs1とＶs2の平均（Ｖs1＋Ｖs2）／２を示す。When the gas detection material part is heated to 800 ° C., the potential differences V s1 and V s2 at the resistances R s1 and R s2 and the average of V s1 and V s2 (V s1 + V s2 ) / 2 are shown. ガス検出材料部分を８５０℃に加熱した場合の、抵抗Ｒs1、Ｒs2での電位差Ｖs1、Ｖs2及びＶs1とＶs2の平均（Ｖs1＋Ｖs2）／２を示す。The average (V s1 + V s2 ) / 2 of potential differences V s1 , V s2 and V s1 and V s2 at the resistances R s1 and R s2 when the gas detection material portion is heated to 850 ° C. is shown. ガス検出材料を８００℃に加熱し、図７の回路及びＶs1とＶs2の電圧を平均するための電圧加算アンプを用いて、電圧加算アンプの出力をセンサ出力Ｖoutputとして求めた結果を示す。The gas detection material is heated to 800 ° C., and the output of the voltage addition amplifier is obtained as the sensor output V output using the circuit of FIG. 7 and the voltage addition amplifier for averaging the voltages of V s1 and V s2. . メタンガスの燃焼反応から、空燃比λと酸素分圧Ｐの関係を求め、空燃比と酸素センサの出力の関係を計算した結果を示す。The relationship between the air-fuel ratio λ and the oxygen partial pressure P is calculated from the combustion reaction of methane gas, and the relationship between the air-fuel ratio and the output of the oxygen sensor is calculated.

Claims (12)

酸化物半導体を使った酸素センサであって、
（１）ガス検出材料である酸化物半導体と基準抵抗とが直列に接続された回路を複数個並列に接続した並列回路を有する、
（２）上記並列回路に一定電圧を負荷したときの、複数個の基準抵抗の電位差の和又は平均、あるいは複数個のガス検出材料の電位差の和又は平均をセンサ出力とする、
（３）複数個のガス検出材料の抵抗値が、酸素分圧の増加に対して増加する関係を有する、
ことを特徴とした酸化物半導体を使った酸素センサ。 An oxygen sensor using an oxide semiconductor,
(1) having a parallel circuit in which a plurality of circuits in which an oxide semiconductor as a gas detection material and a reference resistor are connected in series are connected in parallel;
(2) The sensor output is the sum or average of potential differences of a plurality of reference resistors or the sum or average of potential differences of a plurality of gas detection materials when a constant voltage is applied to the parallel circuit.
(3) The resistance value of the plurality of gas detection materials has a relationship of increasing with respect to the increase of the oxygen partial pressure.
An oxygen sensor that uses an oxide semiconductor. 複数個の基準抵抗の電位差の和又は平均、あるいは複数個のガス検出材料の電位差の和又は平均を求めるための電圧加算回路を有する、請求項１記載の酸化物半導体を使った酸素センサ。   2. The oxygen sensor using an oxide semiconductor according to claim 1, further comprising a voltage addition circuit for obtaining a sum or average of potential differences of a plurality of reference resistors or a sum or average of potential differences of a plurality of gas detection materials. 電圧加算回路の出力である電圧を測定するための回路を有する、請求項２記載の酸化物半導体を使った酸素センサ。   The oxygen sensor using an oxide semiconductor according to claim 2, further comprising a circuit for measuring a voltage that is an output of the voltage adding circuit. 一定電圧を負荷するための定電圧電源を有する、請求項１から３のいずれかに記載の酸化物半導体を使った酸素センサ。   The oxygen sensor using an oxide semiconductor according to any one of claims 1 to 3, further comprising a constant voltage power source for loading a constant voltage. ヒータを有する、請求項１から４のいずれかに記載の酸化物半導体を使った酸素センサ。   The oxygen sensor using an oxide semiconductor according to any one of claims 1 to 4, further comprising a heater. ガス検出材料である酸化物半導体が、酸化セリウム、酸化チタン、酸化ガリウムあるいは酸化スズ、又は、それらの酸化物を含む複合酸化物である、請求項１から５のいずれかに記載の酸化物半導体を使った酸素センサ。   The oxide semiconductor according to any one of claims 1 to 5, wherein the oxide semiconductor that is a gas detection material is cerium oxide, titanium oxide, gallium oxide, tin oxide, or a composite oxide containing such an oxide. Oxygen sensor using 基準抵抗が、抵抗値の温度依存性が酸化物半導体と類似し、かつ、抵抗値の酸素濃度依存性がない温度補償材である、請求項１から６のいずれかに記載の酸化物半導体を使った酸素センサ。   The oxide semiconductor according to any one of claims 1 to 6, wherein the reference resistance is a temperature compensation material in which the temperature dependence of the resistance value is similar to that of the oxide semiconductor and the resistance value does not depend on the oxygen concentration. Used oxygen sensor. 温度補償材が、酸素イオン伝導体である、請求項７記載の酸化物半導体を使った酸素センサ。   The oxygen sensor using an oxide semiconductor according to claim 7, wherein the temperature compensation material is an oxygen ion conductor. 酸化物半導体の形状が厚膜である、請求項１から８のいずれかに記載の酸化物半導体を使った酸素センサ。   The oxygen sensor using an oxide semiconductor according to claim 1, wherein the oxide semiconductor is a thick film. 請求項１から９のいずれかに記載の酸化物半導体を使った酸素センサを構成要素として含むことを特徴とする酸素センサ装置。   An oxygen sensor device comprising the oxygen sensor using the oxide semiconductor according to claim 1 as a constituent element. 請求項１から９のいずれかに記載の酸化物半導体を使った酸素センサを構成要素として含むことを特徴とする燃焼機関の空燃比を制御するための空燃比フィードバック制御システム。   10. An air-fuel ratio feedback control system for controlling an air-fuel ratio of a combustion engine, comprising an oxygen sensor using the oxide semiconductor according to claim 1 as a constituent element. 自動車等の排ガスの空燃比を制御する、請求項１１記載の空燃比フィードバック制御システム。   The air-fuel ratio feedback control system according to claim 11, which controls an air-fuel ratio of exhaust gas from an automobile or the like.
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US10526945B2 (en) 2010-01-29 2020-01-07 Kerdea Technologies, Inc. Microchip oxygen sensor for control of internal combustion engines or other combustion processes
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