JPS60186750A - Device for measuring oxygen concentration - Google Patents
Device for measuring oxygen concentrationInfo
- Publication number
- JPS60186750A JPS60186750A JP59042774A JP4277484A JPS60186750A JP S60186750 A JPS60186750 A JP S60186750A JP 59042774 A JP59042774 A JP 59042774A JP 4277484 A JP4277484 A JP 4277484A JP S60186750 A JPS60186750 A JP S60186750A
- Authority
- JP
- Japan
- Prior art keywords
- oxygen
- air
- electrode
- sensor
- gas
- 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.)
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4071—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure
- G01N27/4072—Cells and probes with solid electrolytes for investigating or analysing gases using sensor elements of laminated structure characterized by the diffusion barrier
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
Abstract
Description
【発明の詳細な説明】
（技術分野）
本発明は酸素濃度測定装置、詳しくは酸素センサを用い
て被測定ガス中の酸素濃度を広範囲に精度よく検出する
酸素濃度測定装置に関する。DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an oxygen concentration measuring device, and more particularly to an oxygen concentration measuring device that accurately detects the oxygen concentration in a gas to be measured over a wide range using an oxygen sensor.
（従来技術）
近時、エンジン吸入混合気の空燃比を精度よく目標値に
制御するために空燃比と相関関係をもつ排気中の酸素濃
度を検出し、この酸素濃度に応じて燃料供給量をフィー
ドバック制御しており、このような空燃比を広範囲に亘
り検出する装置が開発されている。(Prior art) Recently, in order to accurately control the air-fuel ratio of the engine intake air-fuel mixture to a target value, the oxygen concentration in the exhaust gas, which has a correlation with the air-fuel ratio, has been detected, and the fuel supply amount is adjusted according to this oxygen concentration. A device that performs feedback control and detects such an air-fuel ratio over a wide range has been developed.
従来のこの種の酸素センサとしては、例えば特開昭５８
−１５３１５５号公報に記載されたものがあり、第１図
のように示すことができる。第１図において、１は酸素
センサであり、酸素センサ１は酸素濃度に応じて起電力
を発生する一種の濃淡電池の原理を応用したものである
。２．３は酸素イオン伝導性の固体電解質であり、これ
らの第１、第２固体電解質２．３は所定間隔Ｌ（例えば
、Ｌ ＝ ０．１ ｍｍ）を隔てて略平行に配設されて
いる。また、これらの第１、第２固体電解質２．３の間
には支持体４が介設されており、この支持体４は第１、
第２固体電解質２．３と共に間隙部５を画成している。As a conventional oxygen sensor of this kind, for example, Japanese Patent Application Laid-Open No. 58
There is one described in Japanese Patent No.-153155, and it can be shown as shown in FIG. In FIG. 1, reference numeral 1 denotes an oxygen sensor, and the oxygen sensor 1 applies the principle of a type of concentration battery that generates an electromotive force depending on the oxygen concentration. 2.3 is an oxygen ion conductive solid electrolyte, and these first and second solid electrolytes 2.3 are arranged approximately in parallel with a predetermined interval L (for example, L = 0.1 mm) apart. There is. Further, a support 4 is interposed between the first and second solid electrolytes 2.3, and this support 4 is interposed between the first and second solid electrolytes 2.3.
A gap 5 is defined together with the second solid electrolyte 2.3.
間隙部５に臨む第１固体電解質２の一面には酸素電極６
が設けられており、他面には酸素電極６と対向する位置
に基準電極７が設けられている。An oxygen electrode 6 is disposed on one side of the first solid electrolyte 2 facing the gap 5.
A reference electrode 7 is provided on the other side at a position facing the oxygen electrode 6.
そして、これらの各電極６．７にはセンサリード線８．
９がそれぞれ接続されている。一方、間隙部５に臨む第
２固体電解質３の一面には酸素電極６と対向する位置に
カソード電極１０が設けられており、他面にはアノード
電極１１が設けられている。そして、これらの各電極１
０．１１にはポンプリート線１２．１３がそれぞれ接続
されている。上記第１固体電解質２、酸素電極６および
基準電極７はセンサ部１４を構成し、第２固体電解質３
、カソード電極１０およびアノード電極１１はポンプ部
１５を構成している。また、ポンプ部１５の側方には絶
縁性を有するアルミナ基板１７が所定間隔を隔てて略平
行に配設されており、このアルミナ基板１７内には第１
、第２固体電解質２．３の活性を保つように適温に加熱
するヒータ１８が内蔵されている。ポンプ部１５のアノ
ード電極１１には後述する電流供給手段から流し込み電
流（以下、ポンプ電流１ｐという）が供給されており、
このポンプ電流１ｐは第２固体電解質３内をアノード電
極１１からカソード電極ｌＯに向けて流れる。このとき
、ポンプ電流ｒｐの値に応じてカソード電極１０からア
ノード電極１１に向けて第２固体電解質３内を酸素イオ
ンが移動する。したがって、図中ＧＡＳで示すように被
測定ガス、例えば排気を導くと、ポンプ電流１ｐにより
間隙部５の酸素分子がイオンの形で外部に排出される。Each of these electrodes 6.7 is connected to a sensor lead wire 8.
9 are connected to each other. On the other hand, a cathode electrode 10 is provided on one surface of the second solid electrolyte 3 facing the gap 5 at a position facing the oxygen electrode 6, and an anode electrode 11 is provided on the other surface. And each of these electrodes 1
0.11 are connected to pump cleat lines 12 and 13, respectively. The first solid electrolyte 2, the oxygen electrode 6 and the reference electrode 7 constitute a sensor section 14, and the second solid electrolyte 3
, the cathode electrode 10 and the anode electrode 11 constitute a pump section 15. Further, on the side of the pump section 15, an insulating alumina substrate 17 is arranged approximately parallel to each other at a predetermined interval.
A heater 18 is built in to heat the second solid electrolyte 2.3 to an appropriate temperature so as to maintain its activity. An inflow current (hereinafter referred to as pump current 1p) is supplied to the anode electrode 11 of the pump section 15 from a current supply means to be described later.
This pump current 1p flows within the second solid electrolyte 3 from the anode electrode 11 toward the cathode electrode IO. At this time, oxygen ions move within the second solid electrolyte 3 from the cathode electrode 10 toward the anode electrode 11 according to the value of the pump current rp. Therefore, when gas to be measured, such as exhaust gas, is introduced as indicated by GAS in the figure, oxygen molecules in the gap 5 are exhausted to the outside in the form of ions by the pump current 1p.
この場合、間隔１．が極めて狭いため、外部から間隙部
５に流入する酸素分子の量が制限される。このため、間
隙部５の内外部において酸素濃度差が発生し、この酸素
濃度差が所定値になるとセンサ部１４の出力電圧■Ｓが
急変する。この出力電圧Ｖｓの急変する空燃比（以下、
切り換り空燃比という）はポンプ電流１ｐの値に対応し
ており、ポンプ電流ｒｐの増加に伴って、理論空燃比よ
りリーン側に移行する。なお、上記空燃比は、詳しくは
排気中の酸素濃度に対応した空燃比という表現が妥当で
あるが、説明の便宜上、以下単に空燃比という。In this case, the interval 1. Since the gap 5 is extremely narrow, the amount of oxygen molecules flowing into the gap 5 from the outside is limited. For this reason, a difference in oxygen concentration occurs between the inside and outside of the gap portion 5, and when this oxygen concentration difference reaches a predetermined value, the output voltage S of the sensor portion 14 suddenly changes. The air-fuel ratio (hereinafter referred to as
The switching air-fuel ratio (referred to as the switching air-fuel ratio) corresponds to the value of the pump current 1p, and as the pump current rp increases, the air-fuel ratio shifts to a leaner side than the stoichiometric air-fuel ratio. Note that the above air-fuel ratio is appropriately expressed as an air-fuel ratio corresponding to the oxygen concentration in the exhaust gas, but for convenience of explanation, it will be simply referred to as the air-fuel ratio hereinafter.
第２図は、上述した酸素センサ１を用いて空燃比を制御
するものとして、本出願人が先に特許出願した「空燃比
制御装置」 （特願昭５８−７９０３２号）において空
燃比を検出している部分の回路図である。第２図におい
て、酸素センサ１はリード線８．９．１２．１３を介し
て電流供給手段２１および電流値検出手段２２に接続さ
れている。電流供給手段２１はオペアンプＯＰＩ、トラ
ンジスタＱ１、抵抗Ｒ１および基準電源２３により構成
されており、センサ部出力Ｖｓが目標電圧Ｖａとなるよ
うにポンプ部１５にポンプ電流１ｐを供給している。こ
の目標電圧Ｖａはセン号部出力Ｖｓの急変する空燃比（
すなわち、切り換り空燃比）における急変電圧の略中間
値であり、基準電源２３により設定される。FIG. 2 shows the air-fuel ratio detected in the "air-fuel ratio control device" (Japanese Patent Application No. 79032-1981), which the present applicant previously applied for as a patent application, which controls the air-fuel ratio using the oxygen sensor 1 described above. This is a circuit diagram of the part where the In FIG. 2, the oxygen sensor 1 is connected to current supply means 21 and current value detection means 22 via lead wires 8.9.12.13. The current supply means 21 includes an operational amplifier OPI, a transistor Q1, a resistor R1, and a reference power supply 23, and supplies a pump current 1p to the pump section 15 so that the sensor section output Vs becomes the target voltage Va. This target voltage Va is the air-fuel ratio (
That is, it is approximately the intermediate value of the sudden change voltage at the switching air-fuel ratio), and is set by the reference power supply 23.
ここで、目標電圧Ｖａが固定的であるのは、センサ部１
４自体にはポンプ電流１ｐが供給されず、該センサ部１
４の内部抵抗に対してポンプ電流１ｐによる電圧降下分
が出力電圧Ｖｓに上乗せされないからである。これは、
例えば特開昭５７−７６４５０号公報に記載されている
ような単一体の酸素センサと異なり、素子部１６を出力
電圧Ｖｓのみを取り出すセンサ１４と、ポンプ電流Ｉｐ
が供給されるポンプ部１５と、に分割しているためであ
る。したがって、センサ部出力Ｖｓの急変圧力の中間値
は切り換り空燃比の大きさに拘らず略目標電圧Ｖａ程度
となる。そして、この切り換り空燃比はポンプ電流ｒｐ
の大きさに応じて変化する。Here, the target voltage Va is fixed because the sensor unit 1
4 itself is not supplied with the pump current 1p, and the sensor section 1
This is because the voltage drop due to the pump current 1p with respect to the internal resistance of 4 is not added to the output voltage Vs. this is,
For example, unlike a single unit oxygen sensor as described in Japanese Patent Application Laid-Open No. 57-76450, the element section 16 is divided into a sensor 14 that extracts only the output voltage Vs and a pump current Ip.
This is because it is divided into a pump section 15 to which is supplied. Therefore, the intermediate value of the sudden pressure change of the sensor output Vs is approximately equal to the target voltage Va regardless of the magnitude of the switching air-fuel ratio. This switching air-fuel ratio is determined by the pump current rp
It changes depending on the size of.
ポンプ電流１ｐの値は電流値検出手段２２により検出さ
れており、電流値検出手段２２はオペアンプＯＰ２、Ｏ
Ｆ２、抵抗Ｒ２、Ｒ３およびコンデンサＣＩにより構成
されている。そして、電流値検出手段２２はポンプ電流
Ｉｐの値を抵抗Ｒ２の両端間の電圧降下として検出し、
現空燃比を表わず電圧信号Ｖｉを出力している。したが
って、このような装置によれば、被測定ガス中の酸素濃
度、すなわち、空燃比を広範囲に検出することができる
。The value of the pump current 1p is detected by the current value detection means 22, and the current value detection means 22 is detected by the operational amplifiers OP2 and 0.
F2, resistors R2 and R3, and capacitor CI. Then, the current value detection means 22 detects the value of the pump current Ip as a voltage drop across the resistor R2,
It outputs a voltage signal Vi without representing the current air-fuel ratio. Therefore, with such a device, the oxygen concentration in the gas to be measured, that is, the air-fuel ratio, can be detected over a wide range.
しかしながら、このような従来と先願の組み合せに係る
酸素濃度測定装置にあっては、酸素センサ１の間隙部５
の酸素濃度を被測定ガス中の酸素濃度に対して数分の１
の値に維持し、このときのポンプ電流Ｉｐの値を検出し
て空燃比を判断する構成となっていたため、理論空燃比
近傍における空燃比判断が不正確となるという問題点が
あった。However, in the oxygen concentration measuring device according to such a combination of the conventional and the prior application, the gap 5 of the oxygen sensor 1
The oxygen concentration in the measured gas is a fraction of the oxygen concentration in the measured gas.
Since the air-fuel ratio is maintained at a value of , and the air-fuel ratio is determined by detecting the value of the pump current Ip at this time, there is a problem that air-fuel ratio determination near the stoichiometric air-fuel ratio becomes inaccurate.
すなわち、第３図に示すようにポンプ電流Ｉｐの値は酸
素センサ１の切り換り空燃比に対応しており（以下、こ
れらの関係をＩｐ−Ａ／Ｆ特性という）、理論空燃比（
λ＝１）において最小となるもののリッチ（過濃）側に
移行するに従って再び増加する。これば、リッチ域では
排気中に酸素が殆どなく二酸化炭素（Ｃ０２）が多く存
在することから、このＣＯ２の分極反応によりＺｒＯ２
等からなる第２固体電解質３中を酸素イオン０２−が移
動するためで（イオンの移動は、言い換えれば電流であ
る）、排気がリンチ側に移行する程、酸素イオンの移動
量が多くなりポンプ電流Ｉｐの値が増加する。したがっ
て、理論空燃比付近では同一のポンプ電流Ｉｐ値に対し
て切り換り空燃比が２値存在することとなり、単にポン
プ電流１ｐの値に基づいて空燃比を判断するのみでは現
空燃比を一義的に決定することができない。That is, as shown in FIG. 3, the value of the pump current Ip corresponds to the switching air-fuel ratio of the oxygen sensor 1 (hereinafter, these relationships are referred to as Ip-A/F characteristics), and the value of the stoichiometric air-fuel ratio (
Although it is minimum at λ=1), it increases again as it moves to the rich (excessively rich) side. In this case, in the rich region, there is almost no oxygen in the exhaust gas and there is a lot of carbon dioxide (C02), so the polarization reaction of this CO2 causes ZrO2
This is because the oxygen ions 02- move through the second solid electrolyte 3 consisting of (in other words, the movement of ions is an electric current), and the more the exhaust moves to the Lynch side, the more oxygen ions move, and the pump The value of current Ip increases. Therefore, near the stoichiometric air-fuel ratio, there are two switching air-fuel ratios for the same pump current Ip value, and simply determining the air-fuel ratio based on the value of pump current 1p is not sufficient to determine the current air-fuel ratio. cannot be determined.
（発明の目的）
そこで本発明は、センサ部の基準電極側に大気を、酸素
電極側に酸素分子の流入拡散を制限する制限部材を介し
て被測定ガスをそれぞれ導き、酸素電極の酸素分圧を大
気のそれに対して所定比に維持する流し込み電流を供給
することにより、この流し込み電流の値ををリッチ域か
らリーン域までの広範囲な空燃比に一義的に対応させて
、空燃比判断を正確なものとし広範囲な空燃比を正確に
検出することを目的としている。(Objective of the Invention) Therefore, the present invention introduces the atmosphere to the reference electrode side of the sensor part and the gas to be measured to the oxygen electrode side through a restriction member that restricts the inflow and diffusion of oxygen molecules. By supplying a sinking current that maintains the current at a predetermined ratio to that of the atmosphere, the value of this sinking current uniquely corresponds to a wide range of air-fuel ratios from rich to lean regions, making it possible to accurately judge the air-fuel ratio. The purpose is to accurately detect a wide range of air-fuel ratios.
（発明の構成）
本発明による酸素濃度測定装置は、その全体構成図を第
４図に示すように、酸素分子の流入拡散を制限する制限
部材を介して比測定ガスに接する酸素電極と大気に接す
る基準電極が酸素イオン伝導性の固体電解質を挟んで設
けられ、両電極間の酸素分圧比に応じた電圧信号を出力
するセンサ部４３と、流し込み電流の値に応してセンサ
部の両電極間における酸素分圧比を決定するポンプ部４
４と、を有する酸素センサ４５．５１と、前記センサ部
４３の両電極間の酸素分圧比を所定の値に維持してその
出力電圧が所定値となるように前記ポンプ部４４に流し
込み電流を供給する電流供給手段４９と、流し込み電流
の値を検出して被測定ガス中の酸素濃度を算出する酸素
濃度検出手段５０と、を備えており、被測定ガス中の酸
素濃度を正確に判断するものである。(Structure of the Invention) As shown in FIG. 4, the oxygen concentration measuring device according to the present invention connects an oxygen electrode in contact with a ratio measurement gas to the atmosphere through a restriction member that restricts the inflow and diffusion of oxygen molecules. A sensor section 43 is provided with contacting reference electrodes sandwiching an oxygen ion conductive solid electrolyte, and outputs a voltage signal according to the oxygen partial pressure ratio between the two electrodes, and a sensor section 43 that outputs a voltage signal corresponding to the oxygen partial pressure ratio between the two electrodes, and a sensor section 43 that outputs a voltage signal corresponding to the oxygen partial pressure ratio between the two electrodes. Pump section 4 that determines the oxygen partial pressure ratio between
4 and an oxygen sensor 45,51 having an oxygen sensor 45,51, and a current flowing into the pump section 44 so that the oxygen partial pressure ratio between both electrodes of the sensor section 43 is maintained at a predetermined value and the output voltage thereof becomes a predetermined value. It includes a current supply means 49 and an oxygen concentration detection means 50 that detects the value of the injected current and calculates the oxygen concentration in the gas to be measured, and accurately determines the oxygen concentration in the gas to be measured. It is something.
（実施例） 以下、本発明を図面に基づいて説明する。(Example) Hereinafter, the present invention will be explained based on the drawings.
第５〜９図は本発明の第１実施例を示す図であり、本発
明をエンジンの排気中の酸素濃度、ずなわち空燃比を検
出する装置に適用した例である。5 to 9 are diagrams showing a first embodiment of the present invention, and are examples in which the present invention is applied to a device for detecting the oxygen concentration in the exhaust gas of an engine, that is, the air-fuel ratio.
まず、構成を説明すると、第５図は酸素センサの組立要
領を示す斜視図である。第５図において、３１はアルミ
ナ基板であり、アルミナ基板３１の上面（図中上方の端
面）にはヒータ３２を挟んで大気導入板３３が積層され
る。大気導入板３３は酸素イオン伝導性の固体電解質を
主成分としており、その上面側には大気導入溝３３ａが
形成されている。そして、この大気導入板３３の上面側
には平板状の固体電解質３４、空間画成板３５および遮
蔽板３６が略平行に順次積層される。固体電解質３４の
下面には基準電極３７とアノード電極３８が並設配置さ
れており、上面にはこれらの電極３７．３８と対向する
位置にカソード電極３９が配置されている。これらの電
極３７．３８．３９は白金等を主成分とし２ており、例
えば印刷処理により七、下面に積層される。また、これ
らの電極３７．３８．３９にばリ−ド呻４０．４１．４
２がそれぞれ接続されている。空間画成板３５にはカソ
ード電極３９よりやや大きい便形状の孔３５ａが形成さ
れており、また遮蔽板３６には円筒状の拡散孔３６ａが
形成されている。この拡散孔３６ ａの内径は極めて小
さく、例えば０．１ｍ程度に設定される。First, to explain the configuration, FIG. 5 is a perspective view showing the assembly procedure of the oxygen sensor. In FIG. 5, reference numeral 31 denotes an alumina substrate, and an air introduction plate 33 is laminated on the upper surface of the alumina substrate 31 (upper end surface in the figure) with a heater 32 in between. The air introduction plate 33 is mainly composed of an oxygen ion conductive solid electrolyte, and has an air introduction groove 33a formed on its upper surface. A flat solid electrolyte 34, a space defining plate 35, and a shielding plate 36 are sequentially stacked substantially parallel on the upper surface side of the air introduction plate 33. A reference electrode 37 and an anode electrode 38 are arranged side by side on the lower surface of the solid electrolyte 34, and a cathode electrode 39 is arranged on the upper surface at a position facing these electrodes 37, 38. These electrodes 37, 38, and 39 are mainly composed of platinum or the like, and are laminated on the bottom surface by, for example, a printing process. Also, these electrodes 37.38.39 have leads 40.41.4.
2 are connected to each other. A stool-shaped hole 35a slightly larger than the cathode electrode 39 is formed in the space defining plate 35, and a cylindrical diffusion hole 36a is formed in the shielding plate 36. The inner diameter of this diffusion hole 36a is extremely small, for example, set to about 0.1 m.
上記固体電解質３４、基準電極３７およびカソード電極
３９はセンサ部４３を構成しており、センサ部４３にお
りるカソード電極３９は酸素電極としての機能を有して
いる。また、固体電解質３４、アノード電極３８および
カソード電極３９はポンプ部４４を構成しており、さら
にセンサ部４３、ポンプ部４４、遮蔽板３６、空間画成
板３５、大気導入板３３、アルミナ基板３Ｉおよびヒー
タ３２は全体として酸素センサ４５を構成している。The solid electrolyte 34, reference electrode 37, and cathode electrode 39 constitute a sensor section 43, and the cathode electrode 39 in the sensor section 43 has a function as an oxygen electrode. The solid electrolyte 34, anode electrode 38, and cathode electrode 39 constitute a pump section 44, and further include a sensor section 43, a pump section 44, a shielding plate 36, a space defining plate 35, an air introduction plate 33, and an alumina substrate 3I. The heater 32 constitutes an oxygen sensor 45 as a whole.
第６図は上述したように組立られた酸素センサ４５の断
面図である。第６図において、大気導入板３３と固体電
解質３４は大気導入部４６を画成しており、大気導入部
４６には前記第５図に矢印ＡＩＲで示す方向から人気が
導かれる。また、固体電解質３４、空間画成板３５およ
び遮蔽板３Ｇは空間部４７を画成しており、空間部４７
は図中符号ＧＡＳで示すよ・うに被測定ガスの導かれて
いる空間と拡散孔３６ａのみによって連通している。FIG. 6 is a cross-sectional view of oxygen sensor 45 assembled as described above. In FIG. 6, the atmosphere introduction plate 33 and the solid electrolyte 34 define an atmosphere introduction section 46, and popularity is introduced into the atmosphere introduction section 46 from the direction indicated by the arrow AIR in FIG. Further, the solid electrolyte 34, the space defining plate 35, and the shielding plate 3G define a space 47.
As indicated by the symbol GAS in the figure, the space in which the gas to be measured is guided is in communication only through the diffusion hole 36a.
上記空間画成板３５および遮蔽板３６は制限部材４８を
構成しており、制限部材４８は被測定ガス空間Ｇ Ａ
Ｓと空間部４７との間における中位時間当りの酸素分子
の流入拡散量を拡散孔３６ａにより所定値に制限してい
る。したがって、センサ部４３はその基準電極３７側が
人気に接し、酸素電極３９側が制限部材４８を介して被
測定ガスに接することとなり、酸素濃淡電池を形成して
両電極３７．３９間の酸素分圧比に応した起電力Ｅを発
生ずる（後述するネルンスｉ・の式参照）。この起電力
Ｅはセンサ部４３の出力Ｖｓとして外部に取り出される
。The space defining plate 35 and the shielding plate 36 constitute a limiting member 48, and the limiting member 48 defines the gas space to be measured G A
The amount of inflow and diffusion of oxygen molecules per intermediate time between S and the space 47 is limited to a predetermined value by the diffusion hole 36a. Therefore, the sensor section 43 has its reference electrode 37 side in contact with the gas to be measured and its oxygen electrode 39 side in contact with the gas to be measured via the restriction member 48, forming an oxygen concentration cell and increasing the oxygen partial pressure ratio between the two electrodes 37,39. generates an electromotive force E corresponding to (see the Nerns i equation described later). This electromotive force E is taken out to the outside as the output Vs of the sensor section 43.
一方、ポンプ部４４には後述する電流供給手段から流し
込み電流（以下、ポンプ電流という）Ｉｐが供給されて
おり、ポンプ電流１ｐは矢印で示すように固体電解質３
４内をカソード電極３９からアノード電極３８に向けて
流れる。このとき、ポンプ電流ｒｐにより矢印０２−で
示すように７ノード電極３８からアノード電極３９に向
けて酸素イオンが移動する。この酸素イオンの移動量は
ポンプ電流１ｐの値に比例している。したがって、ポン
プ部４４はポンプ電流１ｐの値に応じて大気側の酸素分
子をイオンの形で空間部４７に移動させる。なお、第６
図中ではヒータ３２が省略されているが、ヒータ３２は
固体電解質３４を適温に加熱しその活性を保っている。On the other hand, an inflow current (hereinafter referred to as pump current) Ip is supplied to the pump section 44 from a current supply means to be described later, and the pump current 1p is applied to the solid electrolyte 3 as shown by the arrow.
4 from the cathode electrode 39 to the anode electrode 38. At this time, oxygen ions move from the 7-node electrode 38 toward the anode electrode 39 as indicated by the arrow 02- due to the pump current rp. The amount of movement of this oxygen ion is proportional to the value of the pump current 1p. Therefore, the pump section 44 moves oxygen molecules from the atmosphere side to the space section 47 in the form of ions in accordance with the value of the pump current 1p. In addition, the 6th
Although the heater 32 is omitted in the figure, the heater 32 heats the solid electrolyte 34 to an appropriate temperature and maintains its activity.
第７図は上記酸素センサ４５を使用した酸素濃度測定装
置の回路図である。第７図において、酸素センサ４５は
リード線４０．４１．４２を介して電流供給手段４９お
よび酸素濃度検出手段５０に接続されている。電流供給
手段４９はオペアンプＯＰ４、トランジスタＱ２および
抵抗Ｒ４により構成されており、カソード電極３９の酸
素分圧を基準電極３７の酸素分圧（大気に等しい）と同
一のの値に維持してセンサ部出力Ｖｓが０となるように
ポンプ部４４にポンプ電流１ｐを供給している。ポンプ
電流１ｐの値は酸素濃度検出手段５０により検出されて
おり、酸素濃度手段５０は差動アンプＤＦＩ、オペアン
プＯＰ５、抵抗Ｒ５、Ｒ６およびコンデンサＣ２により
構成されている。そして、酸素濃度検出手段５０はポン
プ電流Ｔｐの値を抵抗Ｒ５の両端間の電圧降下として検
出し、電圧信号Ｖｉを出力している。この電圧信号Ｖｉ
はポンプ電流１ｐの値、すなわち大気側から空間部４７
側に移動する酸素イオンの移動量を表しており、これは
後述するように被測定ガス中の酸素濃度（空燃比）に対
応している。FIG. 7 is a circuit diagram of an oxygen concentration measuring device using the oxygen sensor 45 described above. In FIG. 7, oxygen sensor 45 is connected to current supply means 49 and oxygen concentration detection means 50 via lead wires 40, 41, 42. The current supply means 49 is composed of an operational amplifier OP4, a transistor Q2, and a resistor R4, and maintains the oxygen partial pressure of the cathode electrode 39 at the same value as the oxygen partial pressure of the reference electrode 37 (equal to the atmosphere), and operates the sensor section. A pump current 1p is supplied to the pump section 44 so that the output Vs becomes zero. The value of the pump current 1p is detected by an oxygen concentration detection means 50, which is composed of a differential amplifier DFI, an operational amplifier OP5, resistors R5, R6, and a capacitor C2. The oxygen concentration detection means 50 detects the value of the pump current Tp as a voltage drop across the resistor R5, and outputs a voltage signal Vi. This voltage signal Vi
is the value of the pump current 1p, that is, from the atmospheric side to the space 47
It represents the amount of movement of oxygen ions moving to the side, and this corresponds to the oxygen concentration (air-fuel ratio) in the gas to be measured, as described later.
次に作用を説明する。Next, the effect will be explained.
一般に、Ｉ ｐ−Ａ／Ｆ特性で示したように酸素セン号
の切り換り空燃比は流し込み電流に対応しており、理論
空燃比で最小となるもののリッチ側に移行するに従って
再び増加する。したがって、このような特性を利用して
空燃比を検出する酸素センサでは理論空燃比近傍の空燃
比が不正確とｔ（る。In general, as shown in the Ip-A/F characteristics, the switching air-fuel ratio of the oxygen sensor corresponds to the injected current, and is minimum at the stoichiometric air-fuel ratio, but increases again as it shifts to the rich side. Therefore, in an oxygen sensor that detects the air-fuel ratio using such characteristics, the air-fuel ratio near the stoichiometric air-fuel ratio is inaccurate.
そこで本実施例では、空燃比が無限大である人気がら空
燃比が非富に小さい排気側？、こ酸素分子を移動させる
ようなポンプ電流の値は、排気側での拡散量が所定値に
制限されていれば、現空燃比に一義的に対応させること
ができるという原理に着目して、理論空燃比近傍のポン
プ電流の値ヲー値のみとし空燃比判断を正確に行ってい
る。Therefore, in this embodiment, the exhaust side has an infinite air-fuel ratio, which is popular, but the air-fuel ratio is extremely small. Focusing on the principle that the value of the pump current that moves oxygen molecules can be uniquely matched to the current air-fuel ratio if the amount of diffusion on the exhaust side is limited to a predetermined value, The air-fuel ratio is accurately determined by using only the value of the pump current near the stoichiometric air-fuel ratio.
ＬＥＪ下、最初に」二記原理について説明する。Under LEJ, I will first explain the second principle.
基準電極３７における酸素分圧Ｐａは大気の酸素分圧で
あり、カソード電極３９における酸素分圧Ｐ６は空間部
４７の酸素分圧である。したがって、これらの酸素分圧
Ｐａ、Ｐｂに基づいて両電極３７．３９間に
Ｅ−（ＲＴ／４．Ｆ） ・／ｎ −（Ｐａ／Ｐｔ＋）−
一−−−−■
但し、Ｒ；気体定数
Ｔ：絶対温度
Ｆ：ファラデイ定数
なるネルンストの式によって表される起電力ＩＥが発生
し、センサ部出力Ｖｓとして取り出さ才ｊる。いま、ポ
ンプ部４４にポンプ電流１ｐを供給して酸素ポンプ作用
を行ね−１１、人気側の酸素分子をイオンの形で空間部
４７に移動さゼると、空間部４７の酸素分圧Ｐｂが上昇
する。そしζ１、人気側からの酸素分子の移動量と拡散
孔３６ａを通して排気中に拡散する拡ｔｌ（！量１ｐと
が平衡した時点で空間部４７の酸素分圧ｐｂが安定し、
その大きさが決定される。The oxygen partial pressure Pa at the reference electrode 37 is the oxygen partial pressure of the atmosphere, and the oxygen partial pressure P6 at the cathode electrode 39 is the oxygen partial pressure in the space 47. Therefore, based on these oxygen partial pressures Pa and Pb, E-(RT/4.F) ·/n -(Pa/Pt+)-
1---■ However, R: Gas constant T: Absolute temperature F: Faraday constant An electromotive force IE expressed by Nernst's equation is generated and taken out as the sensor output Vs. Now, supply the pumping current 1p to the pumping section 44 to perform the oxygen pumping action-11. When oxygen molecules on the popular side are moved to the space 47 in the form of ions, the oxygen partial pressure Pb in the space 47 rises. Then, ζ1, when the amount of oxygen molecules transferred from the popular side and the expansion tl (! amount 1p diffused into the exhaust gas through the diffusion hole 36a) are in equilibrium, the oxygen partial pressure pb in the space 47 becomes stable,
Its size is determined.
ここで、Ｐａ＝Ｐｂとなるように、ずなわち、−上記■
式からＶｓ＝０となるようにポンプ電流１ｐを供給する
と、上記拡散量１１）は次式〇で表される。Here, so that Pa=Pb, - above ■
According to the equation, if the pump current 1p is supplied so that Vs=0, the above-mentioned diffusion amount 11) is expressed by the following equation.
ｒｐ ＝Ｋ（Ｐｂ−Ｐｃ）−−−−■
但し、Ｋ：定数
Ｐｃ：排気中の酸素分圧
この場合、Ｐａ＝Ｐｂに維持しているので上記■式にお
いてＰｂ＝Ｐａとおくと、■式は次のように変形できる
。rp = K (Pb - Pc) ----■ However, K: Constant Pc: Oxygen partial pressure in the exhaust In this case, Pa = Pb is maintained, so if Pb = Pa in the above formula (■), The formula can be transformed as follows.
［Ｄ ＃Ｋ （Ｐａ Ｐｃ） −−−−−００式中、拡
散量Ｉ９ は酸素ポンプ作用による大気側からの酸素分
子の移動量と等しく、ポンプ電流＋ｐの値に対応してい
る。したがって、次式■の関係が成立する。[D #K (Pa Pc) ------00 In the formula, the amount of diffusion I9 is equal to the amount of movement of oxygen molecules from the atmosphere side due to the oxygen pumping action, and corresponds to the value of pump current +p. Therefore, the relationship expressed by the following equation (2) holds true.
Ｉｐｏｃｌｐ−−−−・−■
この０式と■とから、
ＩｐｏｃＰａ−ｐｃ−、、−■
なる関係式が導かれる。０式中、Ｐａは大気の酸素分圧
であり、ｐ ａ−−一定（酸素濃度は席に２１％）であ
ることから、第８図に示すようにポンプ電流ｒｐの値は
排気中の酸素分圧Ｐｃに対応したものとなる。したがっ
て、ポンプ電流■ｐの値を検出すれば、排気中の酸素濃
度を一義的に決定することができる。Ipoclp-----■ From this 0 equation and ■, the relational expression IpocPa-pc-,,-■ is derived. In equation 0, Pa is the oxygen partial pressure in the atmosphere, and since p a is constant (the oxygen concentration is 21% in the seat), the value of the pump current rp is determined by the oxygen in the exhaust, as shown in Figure 8. This corresponds to the partial pressure Pc. Therefore, by detecting the value of the pump current ■p, the oxygen concentration in the exhaust gas can be uniquely determined.
次にかかる原理に基づく回路の動作を説明する。Next, the operation of the circuit based on this principle will be explained.
電流供給手段４９はＶｓ＝０となるようにポンプ電流１
ｐを供給することにより、Ｐａ＝Ｐｂなる条件を成立さ
せる。酸素濃度手段５０はこのときのポンプ電流１ｐの
値を検出し、電圧信号Ｖｉとして出力する。このポンプ
電流Ｉｐの値は第９図に示すように、リーン域では空燃
比の増加に伴って、すなわち排気中の酸素分圧ＰＣが小
さくなるに従って徐々に太き（なり、理論空燃比で所定
値Ｔｏとなる。そして、リッチ域では排気中の酸素分子
が極めて少なくなるが、拡散孔３６ａから拡散する酸素
分子０２が排気中のＣＯやＨＣと反応するためより多く
の酸素分子０２がこの拡散孔３６ａから排気中へ流出す
る。The current supply means 49 supplies a pump current of 1 so that Vs=0.
By supplying p, the condition Pa=Pb is established. The oxygen concentration means 50 detects the value of the pump current 1p at this time and outputs it as a voltage signal Vi. As shown in Fig. 9, the value of this pump current Ip gradually increases (becomes) as the air-fuel ratio increases in the lean region, that is, as the oxygen partial pressure PC in the exhaust gas decreases. In the rich region, the number of oxygen molecules in the exhaust gas is extremely small, but since the oxygen molecules 02 diffusing from the diffusion hole 36a react with CO and HC in the exhaust gas, more oxygen molecules 02 are absorbed by this diffusion. It flows out into the exhaust gas from the hole 36a.
よって、第９図に示すようにリッチ域ではｌ。Therefore, as shown in FIG. 9, l in the rich region.
よりさらに大きなポンプ電流１ｐが流れる。An even larger pump current 1p flows.
したがって、ポンプ電流ＩＩ）の値をリッチ域からリー
ン域までの広範囲を空燃比に一義的に対応させることが
でき、現空燃比を正確に検出することができる。Therefore, the value of the pump current II) can be made to correspond uniquely to the air-fuel ratio over a wide range from the rich region to the lean region, and the current air-fuel ratio can be detected accurately.
第１０図は本発明の第２実施例を示す図であり、本実施
例は酸素センサ５１の構造を変更したものである。FIG. 10 is a diagram showing a second embodiment of the present invention, in which the structure of the oxygen sensor 51 is changed.
すなわち、固体電解質３４およびカソード電極３９の上
面は多孔質保護層５２によって被覆されており、この多
孔質保護層５２は制限部材としての機能を有し第１実施
例と同様に酸素分子の流入拡散を制限している。その他
の部分は第１実施例と同様である。That is, the upper surfaces of the solid electrolyte 34 and the cathode electrode 39 are covered with a porous protective layer 52, and this porous protective layer 52 functions as a restricting member and prevents the inflow and diffusion of oxygen molecules as in the first embodiment. is restricted. Other parts are the same as in the first embodiment.
したがって、この第２実施例においても第１実施例と同
様の効果を得ることができる。Therefore, the same effects as in the first embodiment can be obtained in this second embodiment as well.
なお、上記各実施例ではカソード電極をセンザ部の酸素
電極とポンプ部の本来のカソード電極とを兼ね一体化し
たものとして構成しているが、これに限らず、例えば一
体化せずに別体として分割構成し、これらの間を酸素イ
オンの移動が可能な部材（電気の良導体等）で接続する
ようにしてもよい。そして、その場合センサ部出力Ｖｓ
を差動アンプを介して電流供給手段に入力するようにす
れば、センサ部出力Ｖｓに対するポンプ電流■ｐの影響
を排除することができ、空燃比判断の精度をより一層高
めることができる。また％に上記各実施例の基準電極３
７とアノード電極３８を同一の電極で構成しても同様の
効果を得ることができる。Note that in each of the above embodiments, the cathode electrode is configured as an integrated one that serves as the oxygen electrode of the sensor section and the original cathode electrode of the pump section, but the present invention is not limited to this. It is also possible to have a divided configuration, and to connect these parts with a member (such as a good electrical conductor) that allows the movement of oxygen ions. In that case, the sensor unit output Vs
By inputting this into the current supply means via a differential amplifier, the influence of the pump current ■p on the sensor output Vs can be eliminated, and the accuracy of air-fuel ratio judgment can be further improved. In addition, the reference electrode 3 of each of the above examples is expressed as %.
The same effect can be obtained even if the anode electrode 7 and the anode electrode 38 are made of the same electrode.
（効果）
本発明によれば、流し込み電流の値をリッチ域からリー
ン域までの広範囲な空燃比に一義的に対応させることが
でき、空燃比判断を正確なものとしてリッチ域からリー
ン域までの広範囲な空燃比を正確に検出することができ
る。(Effects) According to the present invention, the value of the injected current can be uniquely made to correspond to a wide range of air-fuel ratios from the rich region to the lean region, and the air-fuel ratio judgment can be made accurate. A wide range of air-fuel ratios can be detected accurately.
第１図は従来の酸素センサの断面図、第２．３図ば先願
の空燃比制御装置を示す図であり、第２図はその空燃比
を検出している部分の回路図、第３図はそのＩ ｐ −
Ａ／Ｆ特性を示す図、第４図は本発明の全体構成図、第
５〜９図は本発明の第１実施例を示す図であり、第５図
はその酸素センサの組立要領を示す斜視図、第６図はそ
の酸素センサの断面図、第７図はその回路構成図、第８
図はそのポンプ電流と排気中の酸素分圧との関係を示す
図、第９図はそのＴｐ−Ａ／Ｆ特性を示す図、第１Ｏ図
は本発明の第２実施例を示すその酸素センサの断面図で
ある。
４３−−−−センザ部、
４４−−−−ポンプ部、
４５．５Ｉ−〜−酸素センサ、
４８．５２−−−−−・制限部材、
４９−−−−一電流供給手段、
５０・−−一−−酸素濃度検出手段。
特許出願人 日産自動車株式会社
代理人弁理士 有我軍一部
第１図Figure 1 is a sectional view of a conventional oxygen sensor, Figures 2 and 3 are diagrams showing the air-fuel ratio control device of the prior application, Figure 2 is a circuit diagram of the part that detects the air-fuel ratio, and Figure 3 is a diagram showing the air-fuel ratio control device of the prior application. The figure shows that I p −
FIG. 4 is a diagram showing the A/F characteristics, FIG. 4 is an overall configuration diagram of the present invention, FIGS. 5 to 9 are diagrams showing the first embodiment of the present invention, and FIG. 5 is a diagram showing the assembly procedure of the oxygen sensor. Fig. 6 is a sectional view of the oxygen sensor, Fig. 7 is its circuit configuration diagram, and Fig. 8 is a perspective view.
Figure 9 shows the relationship between the pump current and oxygen partial pressure in the exhaust gas, Figure 9 shows the Tp-A/F characteristics, and Figure 1O shows the oxygen sensor according to the second embodiment of the present invention. FIG. 43-----Sensor section, 44--Pump section, 45.5I--Oxygen sensor, 48.52--Limiting member, 49--Current supply means, 50.- -1--Oxygen concentration detection means. Patent Applicant Nissan Motor Co., Ltd. Representative Patent Attorney Ugagun Part 1 Figure 1
Claims (1)
ガスに接する酸素電極と大気に接する基準電極が酸素イ
オン伝導性の固体電解質を挟んで設けられ、両電極間の
酸素分圧比に応した電圧信号を出力するセンサ部と、流
し込み電流の値に応じてセンサ部の両電極間における酸
素分圧比を決定するポンプ部と、を有する酸素センサと
、前記センサ部の両電極間の酸素分圧比を所定の値に維
持してその出力電圧が所定値となるように前記ポンプ部
に流し込み電流を供給する電流供給手段と、流し込み電
流の値を検出して被測定ガス中の酸素濃度を算出する酸
素濃度検出手段と、を備えたことを特徴とする酸素濃度
測定装置。An oxygen electrode in contact with the gas to be measured and a reference electrode in contact with the atmosphere are provided with an oxygen ion conductive solid electrolyte sandwiched between them, through a restriction member that restricts the inflow and diffusion of oxygen molecules. An oxygen sensor having a sensor section that outputs a voltage signal, and a pump section that determines an oxygen partial pressure ratio between both electrodes of the sensor section according to the value of an injected current, and an oxygen partial pressure ratio between both electrodes of the sensor section. a current supply means for supplying current to the pump section so as to maintain the current at a predetermined value and output voltage thereof to a predetermined value; and detecting the value of the inflow current to calculate the oxygen concentration in the gas to be measured. An oxygen concentration measuring device comprising an oxygen concentration detection means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59042774A JPS60186750A (en) | 1984-03-05 | 1984-03-05 | Device for measuring oxygen concentration |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59042774A JPS60186750A (en) | 1984-03-05 | 1984-03-05 | Device for measuring oxygen concentration |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS60186750A true JPS60186750A (en) | 1985-09-24 |
Family
ID=12645313
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59042774A Pending JPS60186750A (en) | 1984-03-05 | 1984-03-05 | Device for measuring oxygen concentration |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60186750A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4808293A (en) * | 1986-12-19 | 1989-02-28 | Matsushita Electric Industrial Co., Ltd. | Oxygen sensor and method of making such sensor |
-
1984
- 1984-03-05 JP JP59042774A patent/JPS60186750A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4808293A (en) * | 1986-12-19 | 1989-02-28 | Matsushita Electric Industrial Co., Ltd. | Oxygen sensor and method of making such sensor |
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