JP3015673B2 - Method and apparatus for controlling air-fuel ratio sensor - Google Patents
Method and apparatus for controlling air-fuel ratio sensorInfo
- Publication number
- JP3015673B2 JP3015673B2 JP6158853A JP15885394A JP3015673B2 JP 3015673 B2 JP3015673 B2 JP 3015673B2 JP 6158853 A JP6158853 A JP 6158853A JP 15885394 A JP15885394 A JP 15885394A JP 3015673 B2 JP3015673 B2 JP 3015673B2
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- applied voltage
- output current
- voltage value
- 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.)
- Expired - Fee Related
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、内燃機関の空燃比セン
サを制御する空燃比センサの制御方法及び装置に関する
ものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling an air-fuel ratio sensor for controlling an air-fuel ratio sensor of an internal combustion engine.
【０００２】[0002]
【従来技術】内燃機関の燃焼ガスの空燃比を測定するセ
ンサとして、袋管状をした酸素イオン透過性固体電解質
の両面に電極を設けて一方の外側電極を多孔性拡散膜で
被覆した素子の、内側に大気を導入し、外側を測定ガス
にさらし、電極の両端に電圧を印加したとき、測定ガス
の空燃比に応じて素子に流れる限界電流を測定すること
により空燃比を測る限界電流型空燃比センサが知られて
いる。図７は、このような限界電流方式の空燃比センサ
における電極間印加電圧Ｖｓと出力電流Ｉｐの関係を示
すグラフで、空燃比を空気過剰率λ（λ＝空気／燃料）
であらわし、空気過剰率λが０．８からＡＩＲまでの特
性を示している。特性の立上がり部分はセンサの内部抵
抗Ｒｉに主に依存し、印加電圧の増加とともに出力電流
が増加する。フラットな部分は空気過剰率によつてきま
る限界電流領域をあらわす。このフラットな特性は次の
ようにして決まる。センサを流れる電流は、拡散抵抗膜
を透して外側電極に到達した測定ガス中の酸素が電極で
イオン化され、センサに印加された電圧により固体電解
質の中を移動することで発生する。拡散抵抗膜を透して
外側電極に拡散してくる酸素の量は拡散抵抗膜で律速さ
れて空気過剰率λ毎の一定の値となる。このため、出力
電流も印加電圧に依存しない一定の値となる。その範囲
を越えて印加電圧を上げてゆくと、しだいに電解質内の
電子が強制的に流れる電子伝導領域となり、特性は再び
右上がりの傾向を示す。このように、限界電流領域の開
始点と終了点では特性が曲線を描くため、空燃比を測定
するときは、測定点を限界電流領域の特性のフラットな
ところに定めないと、得られる電流−空燃比特性カーブ
が歪んだり、安定した電流値の測定が難しくなり測定精
度が悪くなる問題がある。従来より、このようなセンサ
において電極間に電圧を印加する方法として、空気過剰
率λが１以上のリーン領域の測定の場合、例えば特開昭
５９ー１７０７５８号公報記載のように、出力電流に依
存しない一定電圧Ｖａと電流の立ち上がり部分の傾斜α
を比例係数とする出力電流に比例する電圧Ｖｖを加算し
た電圧Ｖｓ（＝Ｖａ＋Ｖｖ）を印加する方法がある。2. Description of the Related Art As a sensor for measuring the air-fuel ratio of combustion gas of an internal combustion engine, an element in which electrodes are provided on both surfaces of a bag-shaped tubular oxygen ion-permeable solid electrolyte and one outer electrode is covered with a porous diffusion film, A limit current type air that measures the air-fuel ratio by measuring the limit current flowing through the element according to the air-fuel ratio of the measurement gas when the atmosphere is introduced inside, the outside is exposed to the measurement gas, and a voltage is applied to both ends of the electrode. Fuel ratio sensors are known. FIG. 7 is a graph showing the relationship between the inter-electrode applied voltage Vs and the output current Ip in such a limiting current type air-fuel ratio sensor, wherein the air-fuel ratio is expressed by the excess air ratio λ (λ = air / fuel).
, And shows characteristics from an excess air ratio λ of 0.8 to AIR. The rising portion of the characteristic mainly depends on the internal resistance Ri of the sensor, and the output current increases as the applied voltage increases. The flat part represents a limit current region determined by the excess air ratio. This flat characteristic is determined as follows. The current flowing through the sensor is generated when oxygen in the measurement gas that reaches the outer electrode through the diffusion resistance film is ionized by the electrode and moves through the solid electrolyte by the voltage applied to the sensor. The amount of oxygen diffusing into the outer electrode through the diffusion resistance film is determined by the diffusion resistance film and becomes a constant value for each excess air ratio λ. Therefore, the output current also has a constant value independent of the applied voltage. As the applied voltage is increased beyond that range, the region becomes an electron conduction region where electrons in the electrolyte flow forcibly, and the characteristics again show a tendency to rise to the right. As described above, since the characteristic draws a curve at the start point and the end point of the limit current region, when measuring the air-fuel ratio, unless the measurement point is set to a flat portion of the characteristic of the limit current region, the obtained current- There are problems in that the air-fuel ratio characteristic curve is distorted, that the measurement of a stable current value is difficult, and that the measurement accuracy is deteriorated. Conventionally, as a method of applying a voltage between the electrodes in such a sensor, in the measurement of a lean region where the excess air ratio λ is 1 or more, for example, as described in JP-A-59-170758, the output current is reduced. Independent voltage Va and slope α of rising portion of current
There is a method of applying a voltage Vs (= Va + Vv) obtained by adding a voltage Vv that is proportional to an output current with the following equation.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、上記、
従来の方法では、空気過剰率が１以下のリッチ領域まで
電流値の測定範囲を拡大した場合、リツチ領域では飽和
して直線性が劣化し、限界電流領域をはずれてしまい測
定不可能となる場合がある。また、限界領域内に入る場
合でも領域の端にかたより種々の変動で限界電流領域を
外れる可能性が大きく、安定動作の余裕が少ない。SUMMARY OF THE INVENTION However,
In the conventional method, when the measurement range of the current value is expanded to a rich region where the excess air ratio is 1 or less, the saturation occurs in the rich region, the linearity is deteriorated, and the measurement becomes impossible because the linear current deteriorates. There is. In addition, even when entering the limit region, there is a high possibility that the device will fall out of the limit current region due to various changes depending on the end of the region, and there is little margin for stable operation.
【０００４】本発明の目的は、リツチ領域までひろげた
空燃比測定範囲において、空燃比センサ電極へ種々の変
動要因に対しても余裕のある印加電圧の供給を可能とす
る空燃比センサの制御方法及び装置を提供することにあ
る。An object of the present invention is to provide a method of controlling an air-fuel ratio sensor capable of supplying an applied voltage with sufficient margin to various air-fuel ratio sensor electrodes in an air-fuel ratio measurement range extending to a rich region. And a device.
【０００５】[0005]
【課題を解決するための手段】上記目的を達成するため
に、本発明は、袋管状の酸素イオン伝導性固体電解質の
両面に設けられた第１電極および第２電極を有し、前記
第１電極の上に多孔質の拡散抵抗膜を被覆し、前記第２
電極側に大気を導入し、前記第１電極側を測定ガスにさ
らす空燃比センサであって、前記両電極間に電源電圧と
して所定の印加電圧を印加したとき前記両電極間に流れ
る出力電流を測定して空燃比を求める空燃比センサの制
御方法において、前記空燃比を空気過剰率に換算して空
気過剰率が０．１変化する各点毎に、限界電流領域が始
まる開始電圧と限界電流領域が終わる終了電圧の間を一
定比率で分割して前記印加電圧値求め、該求めた各印加
電圧値と前記空燃比センサの前記出力電流の関係を予め
制御回路のマイクロコンピュ−タのデータテーブルに記
憶しておき、周期的に前記空燃比センサの出力電流を前
記マイクロコンピュータに入力することにより、前記記
憶された複数の印加電圧値の中から前記出力電流に対応
した印加電圧値を検索することを特徴とする空燃センサ
の制御方法を提供する。In order to achieve the above object, the present invention has a first electrode and a second electrode provided on both sides of a bag-shaped oxygen ion conductive solid electrolyte, A porous diffusion resistance film is coated on the electrode,
An air-fuel ratio sensor that introduces air to an electrode side and exposes the first electrode side to a measurement gas, and outputs an output current flowing between the two electrodes when a predetermined applied voltage is applied as a power supply voltage between the two electrodes. In the control method of an air-fuel ratio sensor for measuring and obtaining an air-fuel ratio, the starting voltage and the limiting current at which a limit current region starts at each point where the air-fuel ratio is converted into an excess air ratio and the excess air ratio changes by 0.1. The applied voltage value is obtained by dividing the end voltage at which the region ends by a constant ratio, and the relationship between each of the obtained applied voltage values and the output current of the air-fuel ratio sensor is previously stored in a data table of a microcomputer of a control circuit. By inputting the output current of the air-fuel ratio sensor to the microcomputer periodically, an applied voltage value corresponding to the output current is selected from the plurality of stored applied voltage values. Provides a method of controlling the air-fuel sensor, characterized in that the cord.
【０００６】また、上記目的の他の達成手段として、袋
管状の酸素イオン伝導性固体電解質の両面に設けられた
第１電極および第２電極を有し、前記第１電極の上に多
孔質の拡散抵抗膜を被覆し、前記第２電極側に大気を導
入し、前記第１電極側を測定ガスにさらす空燃比センサ
であって、前記両電極間に電源電圧として所定の印加電
圧を印加したとき前記両電極間に流れる出力電流を測定
して空燃比を求める空燃比センサの制御装置において、
前記空燃比を空気過剰率に換算して空気過剰率が０．１
変化する各点毎に、限界電流領域が始まる開始電圧と限
界電流領域が終わる終了電圧の間を一定比率で分割して
前記印加電圧値を求める印加電圧値判定手段と、該印加
電圧値判定手段で求めた各印加電圧値と前記空燃比セン
サの前記出力電流の関係を予め制御回路のマイクロコン
ピュ−タのデータテーブルに記憶するデータ記憶手段
と、周期的に前記空燃比センサの出力電流を前記マイク
ロコンピュータに入力することにより、前記データ記憶
手段に記憶された複数の印加電圧値の中から前記出力電
流に対応した印加電圧値を検索する印加電圧値検索手段
を備えたことを特徴とする空燃センサの制御装置を提供
する。As another means for achieving the above object, a first electrode and a second electrode are provided on both surfaces of a bag-shaped oxygen ion conductive solid electrolyte, and a porous electrode is provided on the first electrode. An air-fuel ratio sensor that covers a diffusion resistance film, introduces air to the second electrode side, and exposes the first electrode side to a measurement gas, and applies a predetermined applied voltage as a power supply voltage between the two electrodes. In the control device of the air-fuel ratio sensor to determine the air-fuel ratio by measuring the output current flowing between the two electrodes,
The air-fuel ratio was converted to an excess air ratio to obtain an excess air ratio of 0.1.
An applied voltage value determining means for dividing the starting voltage at which the limiting current region starts and an ending voltage at which the limiting current region ends at a fixed ratio to obtain the applied voltage value, and Data storage means for storing in advance a relationship between each applied voltage value obtained in the above and the output current of the air-fuel ratio sensor in a data table of a microcomputer of a control circuit; and periodically storing the output current of the air-fuel ratio sensor. An input voltage value searching means for searching an applied voltage value corresponding to the output current from a plurality of applied voltage values stored in the data storage means by inputting the data to a microcomputer; A control device for a fuel sensor is provided.
【０００７】[0007]
【作用】本発明によれば、周期的に空燃比センサの出力
電流をマイクロコンピュータに入力すると、出力電流に
対応した印加電圧がデータテーブルから検索され、空燃
比センサの電極に印加される。データテーブルには、予
め各空燃比において限界電流領域の開始点と終了点を一
定比率で分割することより求められ最も安定した出力電
流が得られる印加電圧が記憶されているので、空燃比セ
ンサはそのときの空燃比において最適の印加電圧に制御
される。これにより、精度の良い、正確な空燃比の測定
が可能となる。According to the present invention, when the output current of the air-fuel ratio sensor is periodically input to the microcomputer, an applied voltage corresponding to the output current is retrieved from the data table and applied to the electrodes of the air-fuel ratio sensor. Since the data table previously stores the applied voltage that is obtained by dividing the start point and the end point of the limit current region at a constant ratio in each air-fuel ratio and obtains the most stable output current, the air-fuel ratio sensor The optimum applied voltage is controlled at the air-fuel ratio at that time. This enables accurate and accurate measurement of the air-fuel ratio.
【０００８】[0008]
【実施例】以下、本発明の一実施例に係る空燃比センサ
の制御方法及び装置について、図面を用いて説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus for controlling an air-fuel ratio sensor according to an embodiment of the present invention will be described with reference to the drawings.
【０００９】図１は、空燃比センサを制御する制御装置
の全体構成を示す。FIG. 1 shows the overall configuration of a control device for controlling an air-fuel ratio sensor.
【００１０】制御装置は、空燃比センサ１０およびマイ
クロコンピュータ１１を含めた制御回路部で構成されて
いる。The control device comprises a control circuit including an air-fuel ratio sensor 10 and a microcomputer 11.
【００１１】マイクロコンピュータ１１には、印加電圧
値判定手段１１０と、データ記憶手段１１２と、印加電
圧値検索手段１１４と、印加電圧値補間計算手段１１６
が備えられている。The microcomputer 11 includes an applied voltage value determining means 110, a data storage means 112, an applied voltage value searching means 114, and an applied voltage value interpolation calculating means 116.
Is provided.
【００１２】印加電圧値判定手段１１０は、空燃比を空
気過剰率に換算して空気過剰率が０．１変化する各点毎
に、限界電流領域が始まる開始電圧と限界電流領域が終
わる終了電圧の間を一定比率で分割して前記印加電圧値
を求める。The applied voltage value determination means 110 converts the air-fuel ratio into an excess air ratio and calculates a start voltage at which the limit current region starts and an end voltage at which the limit current region ends at each point where the excess air ratio changes by 0.1. Is divided at a fixed ratio to obtain the applied voltage value.
【００１３】データ記憶手段１１２は、印加電圧値判定
手段１１０で求めた各印加電圧値と空燃比センサ１０の
出力電流の関係を予めデータテーブル１１２０に記憶す
る。The data storage means 112 stores the relationship between each applied voltage value obtained by the applied voltage value determination means 110 and the output current of the air-fuel ratio sensor 10 in a data table 1120 in advance.
【００１４】印加電圧値検索手段１１４は、周期的に空
燃比センサの出力電流がマイクロコンピュータ１１に入
力されることにより、データ記憶手段１１２に記憶され
た複数の印加電圧値の中から出力電流に対応した印加電
圧値を検索する。When the output current of the air-fuel ratio sensor is input to the microcomputer 11 periodically, the applied voltage value searching means 114 converts the output current from the plurality of applied voltage values stored in the data storage means 112 to the output current. Search for the corresponding applied voltage value.
【００１５】印加電圧値補間計算手段１１６は、印加電
圧値検索手段１１４で検索された印加電圧値を補間計算
する。The applied voltage value interpolation calculating means 116 interpolates and calculates the applied voltage value searched by the applied voltage value searching means 114.
【００１６】制御回路部において、演算増幅器２０，ト
ランジスタ２１，２２からなる回路はプシュプル結合の
出力段をもつゲイン１の増幅器３０であり、入力側に接
続された抵抗１８，１９の分圧電圧Ｖｅを出力し空燃比
センサ１０の第２電極３に一定電圧として供給される。
これにより、空燃比がリーンとリッチで電流Ｉｐの向き
が逆になる場合でも空燃比センサ１０の第１電極２に正
電圧を印加するだけでよいようにしている。演算増幅器
１５，トランジスタ１６，１７からなる回路はプシュプ
ル結合の出力段をもつゲイン１の増幅器４０であり、そ
の出力電圧Ｖａはセンサ出力電流検出用抵抗Ｒ１４を通
して空燃比センサ１０の第１電極２に接続され、この出
力電圧Ｖａと上記分圧電圧Ｖｅの差電圧Ｖｓが空燃比セ
ンサ１０の印加電圧となる。出力電圧ＶａはＤ／Ａ変換
器１２を通してマイクロコンピュータ１１のデジタル出
力で制御され、空燃比センサ１０の印加電圧Ｖｓが空燃
比に応じた電圧になるように制御される。差動増幅器１
３はセンサ出力電流検出用抵抗１４の両端電圧を増幅す
る。マイクロコンピュータ１１はアナログ入力からこの
差動増幅器１３の出力を読み込むことにより空燃比セン
サ１０の出力電流を測定する。In the control circuit section, a circuit comprising an operational amplifier 20 and transistors 21 and 22 is an amplifier 30 having a gain of 1 and having a push-pull output stage, and a divided voltage Ve of resistors 18 and 19 connected to the input side. And is supplied as a constant voltage to the second electrode 3 of the air-fuel ratio sensor 10.
Accordingly, even when the air-fuel ratio is lean and rich and the direction of the current Ip is reversed, it is sufficient to apply only a positive voltage to the first electrode 2 of the air-fuel ratio sensor 10. The circuit including the operational amplifier 15 and the transistors 16 and 17 is an amplifier 40 having a gain of 1 and a push-pull coupling output stage. The output voltage Va is supplied to the first electrode 2 of the air-fuel ratio sensor 10 through a sensor output current detection resistor R14. The difference voltage Vs between the output voltage Va and the divided voltage Ve is the voltage applied to the air-fuel ratio sensor 10. The output voltage Va is controlled by a digital output of the microcomputer 11 through the D / A converter 12, and is controlled so that the applied voltage Vs of the air-fuel ratio sensor 10 becomes a voltage corresponding to the air-fuel ratio. Differential amplifier 1
3 amplifies the voltage between both ends of the sensor output current detecting resistor 14. The microcomputer 11 measures the output current of the air-fuel ratio sensor 10 by reading the output of the differential amplifier 13 from the analog input.
【００１７】図２は、図１の空燃比センサを制御するフ
ローチャートを示す。まず、ステップ２１０で、各空燃
比における空燃比センサ１０ヘの最適な印加電圧値を、
空燃比を空気過剰率に換算して空気過剰率が０．１変化
する各点毎に、限界電流領域が始まる開始電圧と限界電
流領域が終わる終了電圧の間を一定比率で分割して求め
る。次に、求めた印加電圧値と空燃比センサの出力電流
の関係を予め制御回路のマイクロコンピュ−タ１１のデ
ータテーブル１１２０に記憶する（ステップ２１２）。
次に、周期的に空燃比センサの出力電流をマイクロコン
ピュータ１１に入力することにより（ステップ２１
４）、記憶された印加電圧値の中から出力電流に対応し
た印加電圧値を検索する（ステップ２１６）。ここで、
出力電流がデータテーブル１１２０に記憶された印加電
圧値と一致するか否か比較する（ステップ２１８）。一
致する場合は空燃比センサに検索した印加電圧値をその
まま印加する（ステップ２２０）。一致しない場合は補
間により印加電圧値を計算し（ステップ２２２）、計算
した印加電圧値を印加する（ステップ２２０）。FIG. 2 shows a flowchart for controlling the air-fuel ratio sensor of FIG. First, in step 210, the optimum applied voltage value to the air-fuel ratio sensor 10 at each air-fuel ratio is
The air-fuel ratio is converted into an excess air ratio, and for each point where the excess air ratio changes by 0.1, the starting voltage at which the limiting current region starts and the ending voltage at which the limiting current region ends end are divided at a fixed ratio. Next, the relationship between the obtained applied voltage value and the output current of the air-fuel ratio sensor is stored in advance in the data table 1120 of the microcomputer 11 of the control circuit (step 212).
Next, the output current of the air-fuel ratio sensor is periodically input to the microcomputer 11 (step 21).
4) Retrieve the applied voltage value corresponding to the output current from the stored applied voltage values (step 216). here,
It is compared whether the output current matches the applied voltage value stored in the data table 1120 (step 218). If they match, the retrieved applied voltage value is applied to the air-fuel ratio sensor as it is (step 220). If they do not match, the applied voltage value is calculated by interpolation (step 222), and the calculated applied voltage value is applied (step 220).
【００１８】図３は、図１の空燃比センサ１０の構成を
示す。ジルコニアからなる酸素イオン伝導性の固体電解
質１は袋管状の形状をなし、固体電解質１の外側には多
孔質の白金からなる第１電極２が、また内側にも同様に
多孔質の白金からなる第２電極３が被覆されている。そ
して、第１電極２の外側には、多孔質の拡散抵抗体４が
被覆されている。また、固体電解質１の内側にはセラミ
ック保護層で被覆された白金からなるヒータ６が取り付
けられ、ヒータ制御については特に説明しないが、固体
電解質１を動作温度（約６５０゜Ｃ）に加熱する。これ
ら全体はハウジング７内に納められ、ハウジングの外に
出て測定ガスにさらされる拡散抵抗体４の外側には保護
管５が被覆されている。電極２，３及びヒータ６にはリ
−ド線が接続されセンサの外に引き出されている。FIG. 3 shows the configuration of the air-fuel ratio sensor 10 of FIG. The oxygen ion conductive solid electrolyte 1 made of zirconia has a bag-like shape, and a first electrode 2 made of porous platinum is formed on the outside of the solid electrolyte 1, and a porous platinum is formed on the inside similarly. The second electrode 3 is covered. The outside of the first electrode 2 is covered with a porous diffusion resistor 4. A heater 6 made of platinum covered with a ceramic protective layer is attached inside the solid electrolyte 1, and the control of the heater is not particularly described, but the solid electrolyte 1 is heated to an operating temperature (about 650 ° C.). These are all housed in a housing 7, and a protective tube 5 is coated on the outside of the diffusion resistor 4 which comes out of the housing and is exposed to the measurement gas. Lead wires are connected to the electrodes 2 and 3 and the heater 6, and are drawn out of the sensor.
【００１９】図４は、各空燃比における空燃比センサ１
０ヘの最適な印加電圧を示すグラフで、たとえば測定ガ
スが大気のときの限界電流領域に入る最初の電圧をＶ
ｓ’とし限界電流領域の終了点の電圧をＶｓ”としたと
きＶｓ”とＶｓ”間をｍ対ｎの比で分割して求めた電圧
Ｖｓ９を大気時の限界電流測定印加電圧とする。１．５
から０．８の各空気過剰率λにおいても同じ比率で分割
してＶｓ８からＶｓ１を求める。このＶｓ９からＶｓ１
までの値とそのときの出力電流Ｉｐ９からＩｐ１をマイ
クロコンピュータ１１のデータテーブル１１２０に記憶
する。FIG. 4 shows an air-fuel ratio sensor 1 at each air-fuel ratio.
0 is a graph showing an optimum applied voltage to 0. For example, the first voltage that enters the limit current region when the measurement gas is the atmosphere is V
Assuming that s' is the voltage at the end point of the limit current region and Vs ", the voltage Vs9 obtained by dividing Vs" and Vs "by the ratio of m to n is defined as the applied voltage for the limit current measurement in the atmosphere. .5
Vs1 is calculated from Vs8 by dividing the same ratio at each excess air ratio λ from 0.8 to 0.8. From Vs9 to Vs1
And the output currents Ip9 to Ip1 at that time are stored in the data table 1120 of the microcomputer 11.
【００２０】図５は、最適な印加電圧を記憶するデータ
テ−ブル１１２０を示す。空燃比センサ１０の印加電圧
を制御するときは、データテーブル１１２０から、測定
した出力電流に対応した印加電圧を求め、これを空燃比
センサ１０に供給する。例えば、周期的に空燃比センサ
１０の出力電流Ｉｐ９をマイクロコンピュータ１１に入
力すると、出力電流に対応した印加電圧Ｖｓ９がデータ
テーブル１１２０から検索され、空燃比センサの電極に
印加される。データテーブル１１２０には予め各空燃比
における最適な印加電圧が記憶されているので、空燃比
センサはそのときの空燃比において最適の印加電圧に制
御される。FIG. 5 shows a data table 1120 for storing the optimum applied voltage. When controlling the applied voltage of the air-fuel ratio sensor 10, an applied voltage corresponding to the measured output current is obtained from the data table 1120 and supplied to the air-fuel ratio sensor 10. For example, when the output current Ip9 of the air-fuel ratio sensor 10 is periodically input to the microcomputer 11, an applied voltage Vs9 corresponding to the output current is retrieved from the data table 1120 and applied to the electrodes of the air-fuel ratio sensor. Since the optimum applied voltage for each air-fuel ratio is stored in the data table 1120 in advance, the air-fuel ratio sensor is controlled to the optimum applied voltage for the air-fuel ratio at that time.
【００２１】図６は、図２のフローチャートにおけるス
テップ２２２の補間計算のフローチャートを示す。ま
ず、ステップ２３２でマイクロコンピュータ１１は増幅
器１３の出力Ｖｐを読み込み、下記式よりそのときの限
界電流Ｉｐ’を求める。FIG. 6 shows a flowchart of the interpolation calculation in step 222 in the flowchart of FIG. First, in step 232, the microcomputer 11 reads the output Vp of the amplifier 13, and obtains the limit current Ip 'at that time from the following equation.
【００２２】Ｉｐ’＝Ｖｐ／（Ｒ＊Ｇ） ここで Ｒ：電流検出抵抗１４の抵抗値 Ｇ：増幅器１３のゲイン 次に、図５のデータテーブル１１２０を検索し、Ｉｐ’
がテ−ブル上のＩｐと一致しないときは補間により印加
電圧Ｖｓ’を計算する。すなわち、データテーブル１１
２０からＩｐ’より大きいすぐ上のＩｐｎ、Ｉｐ’より
小さいすぐ下のＩｐｎ−１を、またＩｐｎ，Ｉｐｎ−１
に対応するＶｓｎ，Ｖｓｎ−１を求める（ステップ２３
４）。次に、下記式よりＶｓ’をもとめる。Ip '= Vp / (R * G) where R: resistance value of current detection resistor 14 G: gain of amplifier 13 Next, the data table 1120 in FIG.
Does not coincide with Ip on the table, the applied voltage Vs' is calculated by interpolation. That is, the data table 11
20 from Ipn just above Ip ', Ipn-1 just below Ip', and Ipn, Ipn-1
Are obtained (step 23).
4). Next, Vs' is obtained from the following equation.
【００２３】Ｖｓ’＝Ｖｓｎ−１＋（Ｖｓｎ−Ｖｓｎ−
１）＊Ｉｐ’／（Ｉｐｎ−Ｉｐｎ−１） 次に、Ｖｓ’にＶｅを加え、電流検出用抵抗１４の電圧
降下分のＲ＊Ｉｐ’を加算したＶａ（Ｖａ＝Ｖｅ＋Ｖ
ｓ’＋Ｒ＊Ｉｐ’）を求め、このＶａに相当する信号を
Ｄ／Ａコンバータにデジタル出力する（ステップ２３
６）。これにより、限界電流Ｉｐ’が示す空気過剰率λ
のときにおける最適電圧Ｖｓ’を空燃比センサ１０の電
極間に印加することができる。Vs' = Vsn-1 + (Vsn-Vsn-
1) * Ip ′ / (Ipn−Ipn−1) Next, Ve is added to Vs ′, and R * Ip ′ corresponding to the voltage drop of the current detection resistor 14 is added to Va (Va = Ve + V)
s '+ R * Ip'), and digitally outputs a signal corresponding to this Va to the D / A converter (step 23).
6). Thus, the excess air ratio λ indicated by the limit current Ip ′
In this case, the optimum voltage Vs ′ can be applied between the electrodes of the air-fuel ratio sensor 10.
【００２４】[0024]
【発明の効果】本発明によれば、空気過剰率がリッチか
らリーンまでの広い範囲にわたり空燃比センサへの印加
電圧を安定した限界電流領域に設定することにより、精
度が良く、正確な空燃比を測定することができる。According to the present invention, by setting the voltage applied to the air-fuel ratio sensor to a stable limit current region over a wide range from an excess air ratio to a rich air-fuel ratio, a precise and accurate air-fuel ratio can be obtained. Can be measured.
【図１】本発明の一実施例に係る空燃比センサを制御す
る制御装置の全体構成を示すブロック図である。FIG. 1 is a block diagram showing an overall configuration of a control device for controlling an air-fuel ratio sensor according to one embodiment of the present invention.
【図２】図１の空燃比センサを制御するフローチャート
図である。FIG. 2 is a flowchart for controlling the air-fuel ratio sensor of FIG. 1;
【図３】図１の空燃比センサの構成を示す図である。FIG. 3 is a diagram illustrating a configuration of an air-fuel ratio sensor of FIG. 1;
【図４】図１の空燃比センサへの最適な印加電圧を示す
グラフである。FIG. 4 is a graph showing an optimum applied voltage to the air-fuel ratio sensor of FIG. 1;
【図５】最適な印加電圧を記憶するデータテ−ブルを示
す図である。FIG. 5 is a diagram showing a data table for storing an optimum applied voltage.
【図６】図２のステップ２２２の補間計算の詳細を示す
フローチャート図である。FIG. 6 is a flowchart showing details of interpolation calculation in step 222 of FIG. 2;
【図７】従来の電圧印加法に使用した空燃比センサの電
極間印加電圧と出力電流の関係を示すグラフである。FIG. 7 is a graph showing a relationship between an applied voltage between electrodes and an output current of an air-fuel ratio sensor used in a conventional voltage application method.
１…固体電解質、２…第１電極、３…第２電極、４…拡
散抵抗体、１０…空燃比センサ、１１…マイクロコンピ
ュータ、１１０…印加電圧値判定手段、１１２…データ
記憶手段、１１４…印加電圧値検索手段、１１６…印加
電圧値補間計算手段、１１２０…データテーブルDESCRIPTION OF SYMBOLS 1 ... Solid electrolyte, 2 ... 1st electrode, 3 ... 2nd electrode, 4 ... Diffusion resistor, 10 ... Air-fuel ratio sensor, 11 ... Microcomputer, 110 ... Applied voltage value determination means, 112 ... Data storage means, 114 ... Applied voltage value searching means, 116 ... Applied voltage value interpolation calculating means, 1120 ... Data table
───────────────────────────────────────────────────── フロントページの続き (72)発明者 南 直樹 茨城県勝田市大字高場字鹿島谷津2477番 地３ 日立オートモティブエンジニアリ ング株式会社内 審査官 郡山 順 (56)参考文献 特開 昭60−237047（ＪＰ，Ａ) 特開 昭58−172443（ＪＰ，Ａ) 特開 昭60−43139（ＪＰ，Ａ) 特開 昭61−280560（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) G01N 27/41 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Naoki Minami 2477 Kashimayatsu, Kata-shi, Ibaraki Pref. Inspector, Hitachi Automotive Engineering Co., Ltd. Jun Koriyama (56) References 237047 (JP, A) JP-A-58-172443 (JP, A) JP-A-60-43139 (JP, A) JP-A-61-280560 (JP, A) (58) Fields investigated (Int. 7 , DB name) G01N 27/41
Claims (6)
面に設けられた第１電極および第２電極を有し、前記第
１電極の上に多孔質の拡散抵抗膜を被覆し、前記第２電
極側に大気を導入し、前記第１電極側を測定ガスにさら
す空燃比センサであって、前記両電極間に電源電圧とし
て所定の印加電圧を印加したとき前記両電極間に流れる
出力電流を測定して空燃比を求める空燃比センサの制御
方法において、 前記空燃比を空気過剰率に換算して空気過剰率が０．１
変化する各点毎に、限界電流領域が始まる開始電圧と限
界電流領域が終わる終了電圧の間を一定比率で分割して
前記印加電圧の値を求め、該求めた各印加電圧値と前記
空燃比センサの前記出力電流の関係を予め制御回路のマ
イクロコンピュ−タのデータテーブルに記憶しておき、
周期的に前記空燃比センサの出力電流を前記マイクロコ
ンピュータに入力することにより、前記記憶された複数
の印加電圧値の中から前記出力電流に対応した印加電圧
値を検索することを特徴とする空燃センサの制御方法。The present invention has a first electrode and a second electrode provided on both surfaces of a bag-shaped oxygen ion conductive solid electrolyte, and a porous diffusion resistance film is coated on the first electrode. An air-fuel ratio sensor that introduces air to two electrode sides and exposes the first electrode side to a measurement gas, wherein an output current flowing between the two electrodes when a predetermined applied voltage is applied as a power supply voltage between the two electrodes In the control method of the air-fuel ratio sensor for obtaining the air-fuel ratio by measuring the air-fuel ratio,
For each changing point, the value of the applied voltage is obtained by dividing the starting voltage at which the limit current region starts and the end voltage at which the limit current region ends by a fixed ratio, and the obtained applied voltage value and the air-fuel ratio are obtained. The relationship between the output currents of the sensors is stored in advance in a data table of a microcomputer of the control circuit,
By periodically inputting the output current of the air-fuel ratio sensor to the microcomputer, an applied voltage value corresponding to the output current is searched from the stored plurality of applied voltage values. Control method of fuel sensor.
電流は、酸素の拡散速度が前記拡散抵抗体で律速される
ために前記両電極間の印加電圧に依存しない、測定ガス
中の酸素濃度に比例した出力電流となることを特徴とす
る空燃センサの制御方法。2. The method according to claim 1, wherein the output current is not dependent on an applied voltage between the two electrodes because the diffusion rate of oxygen is limited by the diffusion resistor. A method for controlling an air-fuel sensor, wherein an output current is proportional to a concentration.
極に印加する印加電圧値は、前記記憶された複数の印加
電圧値の中から前記出力電流に対応した印加電圧値を検
索し、補間計算して求めることを特徴とする空燃比セン
サの制御方法。3. The method according to claim 1, wherein the applied voltage value applied to the both electrodes is obtained by searching an applied voltage value corresponding to the output current from the stored plurality of applied voltage values, A method for controlling an air-fuel ratio sensor, which is obtained by interpolation calculation.
電流の測定は、８ｍｓ〜４０ｍｓ間隔で周期的に行うこ
とを特徴とする空燃比センサの制御方法。4. The control method for an air-fuel ratio sensor according to claim 1, wherein the measurement of the output current is periodically performed at intervals of 8 ms to 40 ms.
面に設けられた第１電極および第２電極を有し、前記第
１電極の上に多孔質の拡散抵抗膜を被覆し、前記第２電
極側に大気を導入し、前記第１電極側を測定ガスにさら
す空燃比センサであって、前記両電極間に電源電圧とし
て所定の印加電圧を印加したとき前記両電極間に流れる
出力電流を測定して空燃比を求める空燃比センサの制御
装置において、 前記空燃比を空気過剰率に換算して空気過剰率が０．１
変化する各点毎に、限界電流領域が始まる開始電圧と限
界電流領域が終わる終了電圧の間を一定比率で分割して
前記印加電圧値を求める印加電圧値判定手段と、該印加
電圧値判定手段で求めた各印加電圧値と前記空燃比セン
サの前記出力電流の関係を予め制御回路のマイクロコン
ピュ−タのデータテーブルに記憶するデータ記憶手段
と、周期的に前記空燃比センサの出力電流を前記マイク
ロコンピュータに入力することにより、前記データ記憶
手段に記憶された複数の印加電圧値の中から前記出力電
流に対応した印加電圧値を検索する印加電圧値検索手段
を備えたことを特徴とする空燃センサの制御装置。5. A method according to claim 1, further comprising a first electrode and a second electrode provided on both sides of the bag-shaped oxygen ion conductive solid electrolyte, wherein said first electrode is covered with a porous diffusion resistance film. An air-fuel ratio sensor that introduces air to two electrode sides and exposes the first electrode side to a measurement gas, wherein an output current flowing between the two electrodes when a predetermined applied voltage is applied as a power supply voltage between the two electrodes In the control device for an air-fuel ratio sensor that obtains an air-fuel ratio by measuring the air-fuel ratio,
An applied voltage value determining means for dividing the starting voltage at which the limiting current region starts and an ending voltage at which the limiting current region ends at a fixed ratio to obtain the applied voltage value, and Data storage means for storing in advance a relationship between each applied voltage value obtained in the above and the output current of the air-fuel ratio sensor in a data table of a microcomputer of a control circuit; and periodically storing the output current of the air-fuel ratio sensor. An input voltage value searching means for searching an applied voltage value corresponding to the output current from a plurality of applied voltage values stored in the data storage means by inputting the data to a microcomputer; Control device for fuel sensor.
センサの制御装置に、前記印加電圧値検索手段で検索さ
れた前記印加電圧値を補間計算する印加電圧値補間計算
手段を備えたことを特徴とする空燃比センサの制御装
置。6. The control device for an air-fuel sensor according to claim 5, further comprising: an applied voltage value interpolation calculating means for interpolating and calculating the applied voltage value searched by the applied voltage value searching means. A control device for an air-fuel ratio sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6158853A JP3015673B2 (en) | 1994-07-11 | 1994-07-11 | Method and apparatus for controlling air-fuel ratio sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6158853A JP3015673B2 (en) | 1994-07-11 | 1994-07-11 | Method and apparatus for controlling air-fuel ratio sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0829388A JPH0829388A (en) | 1996-02-02 |
| JP3015673B2 true JP3015673B2 (en) | 2000-03-06 |
Family
ID=15680842
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6158853A Expired - Fee Related JP3015673B2 (en) | 1994-07-11 | 1994-07-11 | Method and apparatus for controlling air-fuel ratio sensor |
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| Country | Link |
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|---|---|---|---|---|
| JP5360312B1 (en) | 2013-01-29 | 2013-12-04 | トヨタ自動車株式会社 | Control device for internal combustion engine |
| KR101733329B1 (en) | 2013-01-29 | 2017-05-08 | 도요타지도샤가부시키가이샤 | Control device for internal combustion engine |
| JP2017207397A (en) * | 2016-05-19 | 2017-11-24 | 日本特殊陶業株式会社 | Gas concentration detecting device |
| JP2017207396A (en) * | 2016-05-19 | 2017-11-24 | 日本特殊陶業株式会社 | Gas concentration detecting device |
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