JPH08178896A - Apparatus for diagnosing abnormality of air-fuel ratio detector - Google Patents
Apparatus for diagnosing abnormality of air-fuel ratio detectorInfo
- Publication number
- JPH08178896A JPH08178896A JP6323401A JP32340194A JPH08178896A JP H08178896 A JPH08178896 A JP H08178896A JP 6323401 A JP6323401 A JP 6323401A JP 32340194 A JP32340194 A JP 32340194A JP H08178896 A JPH08178896 A JP H08178896A
- Authority
- JP
- Japan
- Prior art keywords
- fuel ratio
- air
- fuel
- voltage
- oxygen
- 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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Links
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、機関排気中の酸素濃度
に基づいて機関吸入混合気の空燃比を広域にわたって検
出可能な広域型空燃比センサの異常を診断する技術に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for diagnosing an abnormality of a wide area type air-fuel ratio sensor capable of detecting the air-fuel ratio of an engine intake air-fuel mixture over a wide area based on the oxygen concentration in engine exhaust.
【０００２】[0002]
【従来の技術】燃費の向上を目的として、理論空燃比
(14.7) よりも高い空燃比 (例えば20〜25) で燃焼を行
わせるようにした稀薄燃焼機関が近年提案されている。
かかる稀薄燃焼を高精度に制御するためには、前記理論
空燃比よりも高い空燃比 (リーン空燃比) を検出できる
センサが必要になる。2. Description of the Related Art The theoretical air-fuel ratio is used to improve fuel efficiency.
In recent years, a lean-burn engine has been proposed in which combustion is performed at an air-fuel ratio higher than (14.7) (for example, 20 to 25).
In order to control such lean burn with high accuracy, a sensor capable of detecting an air-fuel ratio (lean air-fuel ratio) higher than the stoichiometric air-fuel ratio is required.
【０００３】上記のように理論空燃比よりもリーン (リ
ッチ) な空燃比を検出できる空燃比センサ (以下広域型
空燃比センサと称する。) としては、ＳＡＥ paper 853
78において示されているものがある。このものの原理を
簡単に説明すると、酸素濃度一定の基準ガス (例えば大
気)が導かれる基準ガス室と、排気が小孔から導かれる
排気室とに両面を臨ませて酸素イオン伝導性固体電解質
からなるセンサセルを設け、その両面に設けた第１の電
極間に発生する電圧により前記基準ガスと排気との酸素
濃度比を検出する濃度検出部を備える。一方、前記排気
室と排気通路とを前記小孔を残して大略覆う酸素イオン
伝導性固体電解質からなるポンプセルを設け、該ポンプ
セルの排気室と排気通路に臨む両面に設けた第２の電極
間に前記酸素濃度比に応じた電圧 (を増幅した電圧) を
印加して前記ポンプセルを介して排気室に排気通路との
間酸素イオンを汲み出したり汲み入れたりしてで排気室
と基準ガス室との酸素濃度比を所定値 (排気が理論空燃
比となる状態) に近づける方向に制御する酸素ポンプ部
を備える。それによって生じる電流値 (限界電流値) を
測定することによって、排気中の酸素濃度ひいては機関
吸入混合気中の空燃比を検出するようになっている。As an air-fuel ratio sensor capable of detecting an air-fuel ratio leaner than the stoichiometric air-fuel ratio as described above (hereinafter referred to as a wide area type air-fuel ratio sensor), SAE paper 853.
Some are shown in 78. To briefly explain the principle of this, the oxygen ion-conducting solid electrolyte is exposed by facing both sides to a reference gas chamber in which a reference gas with a constant oxygen concentration (for example, the atmosphere) is introduced and an exhaust chamber in which exhaust gas is introduced through small holes. And a concentration detector for detecting the oxygen concentration ratio between the reference gas and the exhaust gas by the voltage generated between the first electrodes provided on both sides of the sensor cell. On the other hand, a pump cell made of an oxygen ion conductive solid electrolyte that substantially covers the exhaust chamber and the exhaust passage except for the small holes is provided, and between the exhaust chamber of the pump cell and the second electrodes provided on both surfaces facing the exhaust passage. By applying a voltage (amplified voltage) according to the oxygen concentration ratio and pumping out or pumping oxygen ions between the exhaust chamber and the exhaust passage through the pump cell, the exhaust chamber and the reference gas chamber are separated from each other. An oxygen pump unit is provided for controlling the oxygen concentration ratio so as to approach a predetermined value (a state in which the exhaust gas has a stoichiometric air-fuel ratio). By measuring the resulting current value (limit current value), the oxygen concentration in the exhaust gas and thus the air-fuel ratio in the engine intake air-fuel mixture is detected.
【０００４】[0004]
【発明が解決しようとする課題】ところで、この種の広
域型空燃比センサにおいては、前記第２の酸素イオン伝
導性固体電解質に印加される電圧が異常に増大すると該
固体電解質の黒化現象を招き、該黒化の度合いが進行す
ると固体電解質が損傷されやすくなるという問題があ
り、そのため、例えば特開昭62−81559 号公報に示され
るように印加電圧を検出して所定レベルを超えたときに
印加を停止又は制限することが提案されている。By the way, in this type of wide area type air-fuel ratio sensor, when the voltage applied to the second oxygen ion conductive solid electrolyte is abnormally increased, the blackening phenomenon of the solid electrolyte is caused. However, there is a problem that the solid electrolyte is likely to be damaged as the degree of blackening progresses. Therefore, for example, when the applied voltage is detected and a predetermined level is exceeded, as shown in JP-A-62-81559. It has been proposed to stop or limit the application.
【０００５】ところが、上記のように酸素イオン伝導性
固体電解質への印加電圧が異常に増大するのは、実際に
センサやその制御回路に異常が無くとも機関の運転状態
を要因として発生する場合があることが判明した。即
ち、印加電圧は、図７ (Ａ) に示すように、排気空燃比
が理論空燃比から外れるほど大きく発生するように構成
されており、また、同図 (Ｂ) に示すようにポンプセル
が低温であるほど電極面での酸素イオン化反応の促進に
要するエネルギーが増大して内部抵抗が増大し、それに
よって印加電圧が増大する傾向がある。この他、同図
(Ｃ) に示すようにセンサの熱劣化 (耐久時間) が進む
ほど低温時と同様イオン化性能が低下して内部抵抗の増
大により印加電圧が増大する。However, the abnormal increase in the voltage applied to the oxygen ion conductive solid electrolyte as described above may occur due to the operating state of the engine even if there is no abnormality in the sensor or its control circuit. It turned out to be. That is, as shown in FIG. 7 (A), the applied voltage is so configured that it becomes large as the exhaust air-fuel ratio deviates from the stoichiometric air-fuel ratio, and as shown in FIG. The higher the value, the more the energy required for promoting the oxygen ionization reaction on the electrode surface increases, and the internal resistance increases, which tends to increase the applied voltage. Besides this, the same figure
As shown in (C), as the heat deterioration (durability time) of the sensor progresses, the ionization performance decreases as in the case of low temperature, and the applied voltage increases due to the increase in internal resistance.
【０００６】したがって、これらの印加電圧を増大させ
る条件が組み合わされると、印加電圧が異常に増大する
可能性がでてくる。通常の運転状態では空燃比は制御範
囲内にあり、排気温度も十分高いため、運転状態によっ
て印加電圧が異常となることはないが、例えば、減速運
転時等で燃費向上のため燃料供給を停止するとき (燃料
カット) には、燃焼が行われないため、排気として吸入
された空気がそのまま排出され、空燃比が理論空燃比か
ら大きく外れると共に、排気温度も大きく低下するた
め、印加電圧が異常に上昇してしまうこととなる。Therefore, if these conditions for increasing the applied voltage are combined, the applied voltage may increase abnormally. In normal operating conditions, the air-fuel ratio is within the control range and the exhaust gas temperature is sufficiently high, so the applied voltage does not become abnormal depending on operating conditions.However, for example, during deceleration operation, fuel supply is stopped to improve fuel efficiency. When (fuel cut) is performed, combustion is not performed, so the air taken in as exhaust gas is discharged as it is, the air-fuel ratio greatly deviates from the stoichiometric air-fuel ratio, and the exhaust gas temperature also drops significantly, so the applied voltage is abnormal. Will rise to.
【０００７】その結果、センサや制御回路が正常であっ
ても異常であると誤判定されやすくなり (特に、劣化の
進んだセンサでは誤判定されやすい) 、一旦異常と判定
されると、以後の空燃比フィードバック制御が停止さ
れ、良好な空燃比制御が行えず、リーン空燃比運転の停
止等により燃費の向上が妨げられることとなる。本発明
は、このような従来の問題点に鑑みなされたもので、広
域型空燃比センサの酸素ポンプ部への印加電圧の異常の
診断を適切な運転条件でのみ行うことにより誤診断を防
止できるようにした内燃機関の空燃比検出装置の異常診
断装置を提供することを目的とする。As a result, even if the sensor or the control circuit is normal, it is apt to be erroneously determined to be abnormal (in particular, a sensor that has deteriorated is apt to be erroneously determined). The air-fuel ratio feedback control is stopped, good air-fuel ratio control cannot be performed, and the lean air-fuel ratio operation is stopped, which hinders improvement in fuel consumption. The present invention has been made in view of the above-mentioned conventional problems, and erroneous diagnosis can be prevented by diagnosing an abnormality in the voltage applied to the oxygen pump portion of the wide area type air-fuel ratio sensor only under appropriate operating conditions. An object of the present invention is to provide an abnormality diagnosis device for an air-fuel ratio detection device for an internal combustion engine as described above.
【０００８】[0008]
【課題を解決するための手段】このため請求項１の発明
に係る内燃機関の空燃比検出装置は、図１に示すよう
に、第１の酸素イオン伝導性固体電解質を挟んで両側に
基準酸素濃度を有する基準ガスが導かれる基準ガス室と
内燃機関の排気通路中の排気が導かれる排気室とを備
え、該第１の酸素イオン伝導性固体電解質の基準ガス室
と排気室とに面する両面に夫々設けられた第１の電極間
に前記両室の酸素濃度比に応じた電位差を発生する酸素
濃度検出部と、前記排気室と排気通路との間を排気の導
入孔を残して大略覆う第２の酸素イオン伝導性固体電解
質の排気通路側と排気室側とに面する両面に夫々設けら
れた第２の電極間に電圧を印加されることにより排気通
路と排気室との間で第２の酸素イオン伝導性固体電解質
を介して酸素イオンを輸送する酸素ポンプ部と、を備え
てなる広域型空燃比センサと、前記酸素濃度検出部で検
出される両室の酸素濃度比に応じた電圧を印加して酸素
ポンプ部で酸素イオンを輸送させるセンサ制御回路と、
からなり、前記酸素イオン輸送時に第２の電極間に流れ
る電流値によって排気中の酸素濃度を検出し、以て機関
吸入混合気の空燃比を検出するように構成された内燃機
関の空燃比検出装置において、機関の運転状態の要因に
よって前記第２の電極間に印加される電圧が正常範囲か
ら外れる所定の運転状態を検出する所定運転状態検出手
段と、前記第２の電極間に印加される電圧の異常の有無
を、前記所定の運転状態以外の運転状態のときに診断す
る異常診断手段を設けたことを特徴とする。Therefore, an air-fuel ratio detecting device for an internal combustion engine according to a first aspect of the present invention, as shown in FIG. 1, has reference oxygen on both sides with a first oxygen ion conductive solid electrolyte interposed therebetween. A reference gas chamber into which a reference gas having a concentration is introduced and an exhaust chamber into which exhaust gas in an exhaust passage of an internal combustion engine is introduced are provided, and the first oxygen ion conductive solid electrolyte reference gas chamber and the exhaust chamber face each other. An oxygen concentration detection unit that generates a potential difference according to the oxygen concentration ratio between the two chambers is provided between the first electrodes provided on both surfaces, and an exhaust gas introduction hole is left between the exhaust chamber and the exhaust passage. By applying a voltage between the second electrodes provided on both sides of the second oxygen ion conductive solid electrolyte covering the exhaust passage side and the exhaust chamber side, the voltage is applied between the exhaust passage and the exhaust chamber. Oxygen ions are transferred through the second oxygen ion conductive solid electrolyte. A wide-range air-fuel ratio sensor including an oxygen pump unit for sending oxygen, and a voltage according to the oxygen concentration ratio of both chambers detected by the oxygen concentration detection unit is applied to transport oxygen ions in the oxygen pump unit. A sensor control circuit,
And an air-fuel ratio detection of an internal combustion engine configured to detect the oxygen concentration in the exhaust gas by the value of the current flowing between the second electrodes during the transport of oxygen ions, thereby detecting the air-fuel ratio of the engine intake air-fuel mixture. In the device, the voltage applied between the second electrodes is applied between the second electrode and a predetermined operation state detecting unit that detects a predetermined operation state in which the voltage applied between the second electrodes is out of the normal range due to the factor of the operation state of the engine. An abnormality diagnosing means for diagnosing the presence or absence of a voltage abnormality in an operating state other than the predetermined operating state is provided.
【０００９】また、請求項２に係る発明では、前記所定
運転状態検出手段は、機関への燃料の供給が停止される
運転状態を前記所定の運転状態として検出することを特
徴とする。また、請求項３に係る発明では、前記所定運
転状態検出手段は、前記内燃機関への燃料の供給が停止
される運転状態の終了後も所定時間継続して、前記所定
の運転状態として検出することを特徴とする。Further, in the invention according to claim 2, the predetermined operation state detecting means detects an operation state in which the supply of fuel to the engine is stopped as the predetermined operation state. Further, in the invention according to claim 3, the predetermined operation state detection means continues for a predetermined time even after the end of the operation state in which the supply of fuel to the internal combustion engine is stopped, and detects the predetermined operation state. It is characterized by
【００１０】また、請求項４に係る発明では、前記前記
所定時間は、前記内燃機関への燃料の供給が停止される
運転状態の継続時間に応じて設定されることを特徴とす
る。また、請求項５に係る発明では、前記内燃機関への
燃料の供給が停止される運転状態の継続時間を燃料供給
停止開始時の機関回転速度によって推定して前記所定時
間を設定することを特徴とする。The invention according to claim 4 is characterized in that the predetermined time is set according to a duration of an operating state in which the supply of fuel to the internal combustion engine is stopped. Further, in the invention according to claim 5, the predetermined time is set by estimating the duration of the operating state in which the fuel supply to the internal combustion engine is stopped by the engine rotation speed at the start of the fuel supply stop. And
【００１１】[0011]
【作用】請求項１の発明によると、広域型空燃比センサ
の酸素イオンを輸送する第２の酸素イオン伝導性固体電
解質の第２の電極間に印加される電圧が、機関の運転状
態の要因で正常範囲から外れるようなときには、該印加
電圧の異常の診断が行われないようにしたので、空燃比
検出装置が正常である場合に前記運転状態の要因で異常
と誤判定されることが防止できる。According to the invention of claim 1, the voltage applied between the second electrodes of the second oxygen ion conductive solid electrolyte for transporting oxygen ions of the wide area type air-fuel ratio sensor is a factor of the operating state of the engine. When the air-fuel ratio detecting device is out of the normal range, the abnormality of the applied voltage is not diagnosed. it can.
【００１２】請求項２の発明によると、燃料供給停止時
は広域型空燃比センサの排気室に大気が直接導かれるの
で通常の排気が導かれる場合の両室の酸素濃度比の範囲
から大きく外れた酸素濃度比となり、かつ、排気温度が
大気温度近くまで低下して第２の酸素イオン伝導性固体
電解質の内部抵抗が増大することにより、第２の電極間
に印加される電圧が異常な値となりやすい。そこで、該
燃料停止時を異常診断を停止する所定の運転状態として
検出することにより、異常の診断精度が向上する。According to the second aspect of the present invention, when the fuel supply is stopped, the atmosphere is directly introduced into the exhaust chamber of the wide area type air-fuel ratio sensor, so that the range of the oxygen concentration ratio of both chambers when the normal exhaust is introduced is largely deviated. Oxygen concentration ratio, and the exhaust temperature decreases to near atmospheric temperature and the internal resistance of the second oxygen ion conductive solid electrolyte increases, so that the voltage applied between the second electrodes becomes an abnormal value. It is easy to become. Therefore, by detecting the time when the fuel is stopped as a predetermined operating state in which the abnormality diagnosis is stopped, the accuracy of the abnormality diagnosis is improved.
【００１３】請求項３の発明によると、前記燃料供給停
止終了後も排気通路中に大気が残存し、また、燃料供給
再開後の排気熱で広域型空燃比センサの温度が高まるの
に遅れがあること等により、前記印加電圧が正常範囲に
確実に復帰するのに時間遅れを要するので、該所定時間
が経過するまで異常診断を停止することにより、診断精
度をより向上できる。According to the third aspect of the invention, the atmosphere remains in the exhaust passage even after the fuel supply is stopped, and there is a delay in the temperature of the wide area type air-fuel ratio sensor rising due to the exhaust heat after the fuel supply is restarted. As a result, there is a time delay for the applied voltage to reliably return to the normal range. Therefore, by stopping the abnormality diagnosis until the predetermined time elapses, the diagnostic accuracy can be further improved.
【００１４】請求項４の発明によると、特に、前記燃料
供給停止時間が長いほど大気による広域型空燃比センサ
の冷却量が多く、燃料供給再開後に温まるまでの時間遅
れが大きくなるので、該燃料供給停止時間に応じて燃料
供給再開後の異常診断停止時間を設定することで、必要
かつ十分な時間に設定できる。請求項５の発明による
と、前記燃料供給停止時間は燃料供給停止開始時の機関
回転速度が高速であるほど、長引くことになるので、該
機関回転速度に基づいて燃料供給再開後の異常診断停止
時間を容易に設定することができる。According to the invention of claim 4, in particular, as the fuel supply stop time is longer, the amount of cooling of the wide area type air-fuel ratio sensor by the atmosphere is larger, and the time delay until the fuel is warmed after the fuel supply is restarted becomes larger. By setting the abnormality diagnosis stop time after resuming fuel supply according to the supply stop time, it is possible to set the necessary and sufficient time. According to the invention of claim 5, the fuel supply stop time becomes longer as the engine rotation speed at the start of the fuel supply stop becomes longer. Therefore, based on the engine rotation speed, the abnormality diagnosis stop after the fuel supply is restarted. The time can be easily set.
【００１５】[0015]
【実施例】以下に本発明の実施例を図に基づいて説明す
る。図１は、広域型空燃比センサのセンサ素子の構造
と、そのポンプ電圧の制御回路及び該ポンプ電圧の異常
を診断する回路を示す。広域型空燃比センサのセンサ素
子の構造について説明すると、例えば白金で構成された
ヒータ１を装着したアルミナ等からなる基板２上に先端
側が閉塞する平面コ字型の例えばアルミナからなる平板
３を設けて基準の酸素濃度を有するガスとして大気が導
入される基準ガス室４を形成し、前記平板３上には酸素
濃度検出部５を設けてある。この酸素濃度検出部５は、
第１の酸素イオン伝導性固体電解質であるジルコニアで
形成されたセンサセル６の基準ガス室４側に白金からな
る検出電極７を設け、反対側に同じく白金からなる検出
電極８を設けて構成される。更に、この酸素濃度検出部
５の上方に機関排気が導入される排気室９を介して酸素
ポンプ部10が設けられる。この酸素ポンプ部10は、酸素
イオン伝導性固体電解質であるジルコニアで形成された
ポンプセル11の両面に白金からなるポンプ電極12，13を
設けると共に、前記排気室９に機関排気を導入する排気
導入孔14を設けて構成される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of a sensor element of a wide area type air-fuel ratio sensor, its pump voltage control circuit, and a circuit for diagnosing an abnormality in the pump voltage. Explaining the structure of the sensor element of the wide area type air-fuel ratio sensor, for example, a flat plate 3 made of, for example, alumina having a flat U-shape whose front end is closed is provided on a substrate 2 made of alumina or the like on which a heater 1 made of platinum is mounted. A reference gas chamber 4 into which the atmosphere is introduced as a gas having a reference oxygen concentration is formed, and an oxygen concentration detector 5 is provided on the flat plate 3. The oxygen concentration detector 5
A detection electrode 7 made of platinum is provided on the side of the reference gas chamber 4 of the sensor cell 6 made of zirconia, which is the first oxygen ion conductive solid electrolyte, and a detection electrode 8 made of platinum is also provided on the opposite side. . Further, an oxygen pump unit 10 is provided above the oxygen concentration detection unit 5 via an exhaust chamber 9 into which engine exhaust is introduced. This oxygen pump unit 10 has pump electrodes 12 and 13 made of platinum provided on both surfaces of a pump cell 11 made of zirconia which is an oxygen ion conductive solid electrolyte, and an exhaust introduction hole for introducing engine exhaust to the exhaust chamber 9. It is configured by providing 14.
【００１６】そして、基準ガス室４内の大気 (酸素濃度
略一定) と排気室９内の排気との酸素濃度の比によって
検出電極７，８間に電位差Ｖ1 が生じる。かかる構成の
広域型空燃比センサが、以下のセンサ制御回路によって
制御される。前記検出電極７，８間に生じた電位差Ｖ1
が増幅器15の−側入力端子に入力され、増幅器15の＋側
入力端子には基準電圧Ｖ0 が入力される。該基準電圧Ｖ
0 は排気室９に理論空燃比の排気が導かれたときに基準
ガス室４内の基準ガス (大気) との酸素濃度比によって
前記検出電極７，８間に生じる電位差Ｖ1 と等しい値に
設定されている。前記増幅器15の出力電圧が電流検出用
抵抗16を介してポンプセル11の外側のポンプ電極12に印
加される。排気室９に面したポンプ電極12及び検出電極
８は接地されている。前記電流検出用抵抗16の端子電圧
が空燃比検出信号としてコントロールユニット17に入力
される。A potential difference V 1 is generated between the detection electrodes 7 and 8 depending on the ratio of the oxygen concentrations of the atmosphere in the reference gas chamber 4 (oxygen concentration is substantially constant) and the exhaust gas in the exhaust chamber 9. The wide area type air-fuel ratio sensor having such a configuration is controlled by the following sensor control circuit. The potential difference V 1 generated between the detection electrodes 7 and 8
Is input to the negative side input terminal of the amplifier 15, and the reference voltage V 0 is input to the positive side input terminal of the amplifier 15. The reference voltage V
The value 0 is equal to the potential difference V 1 generated between the detection electrodes 7 and 8 due to the oxygen concentration ratio with the reference gas (atmosphere) in the reference gas chamber 4 when the exhaust of the stoichiometric air-fuel ratio is guided to the exhaust chamber 9. It is set. The output voltage of the amplifier 15 is applied to the pump electrode 12 outside the pump cell 11 via the current detecting resistor 16. The pump electrode 12 and the detection electrode 8 facing the exhaust chamber 9 are grounded. The terminal voltage of the current detection resistor 16 is input to the control unit 17 as an air-fuel ratio detection signal.
【００１７】次に、前記広域型空燃比センサとセンサ制
御回路からなる空燃比検出装置の作用を説明する。リー
ン空燃比で運転中は理論空燃比よりリーンな排気が排気
室９内に導かれ、基準ガス室４の大気に対する酸素濃度
比が理論空燃比の排気が導かれる場合より増大する。そ
こで、前記酸素濃度比に応じて発生する検出電極７，８
間の電位差Ｖ1 が、理論空燃比に対応する基準電圧Ｖ0
より小さくなり、その差に応じて増幅された正の電圧が
増幅器15から出力され、該出力電圧に応じたポンプ電圧
ＶPがポンプセル11のポンプ電極12，13間に印加され
る。その結果、排気室15内の酸素がポンプセルに流れる
電流に比例した量だけ酸素イオンとなってポンプセル11
を介して外部 (排気通路側) へ汲み出される。そして、
印加電圧が所定値以上になると、流れる電流は限界値に
達し、この限界電流値をコントロールユニット17によっ
て測定することにより排気中の酸素濃度、即ち吸入混合
気の空燃比を検出できる。リッチ空燃比で運転中は前記
とは逆に検出電極７，８間の電位差Ｖ1 が、基準電圧Ｖ
0 より小さくなり、負のポンプ電圧ＶP がポンプ電極1
2，13間に印加され、排気通路側の排気中の酸素イオン
がポンプセル11を介して排気室９内に汲み入れられ、リ
ーン運転時とは逆向きの限界電流値を測定することによ
り、リッチ空燃比を検出できる。Next, the operation of the air-fuel ratio detecting device comprising the wide area type air-fuel ratio sensor and the sensor control circuit will be described. During operation with a lean air-fuel ratio, exhaust gas leaner than the stoichiometric air-fuel ratio is introduced into the exhaust chamber 9, and the oxygen concentration ratio of the reference gas chamber 4 to the atmosphere is higher than when exhaust gas with the stoichiometric air-fuel ratio is introduced. Therefore, the detection electrodes 7 and 8 generated according to the oxygen concentration ratio
A potential difference V 1 between the reference voltage V 0 corresponding to the stoichiometric air-fuel ratio
The positive voltage which becomes smaller and is amplified according to the difference is output from the amplifier 15, and the pump voltage V P according to the output voltage is applied between the pump electrodes 12 and 13 of the pump cell 11. As a result, oxygen in the exhaust chamber 15 becomes oxygen ions in an amount proportional to the current flowing through the pump cell, and the pump cell 11
It is pumped out to the outside (exhaust passage side) via. And
When the applied voltage exceeds a predetermined value, the flowing current reaches a limit value, and by measuring this limit current value by the control unit 17, the oxygen concentration in the exhaust gas, that is, the air-fuel ratio of the intake air-fuel mixture can be detected. Contrary to the above, during operation with a rich air-fuel ratio, the potential difference V 1 between the detection electrodes 7 and 8 is the reference voltage V
Is less than 0 , and the negative pump voltage V P is less than 0
Oxygen ions in the exhaust gas on the side of the exhaust passage are pumped into the exhaust chamber 9 via the pump cell 11 by measuring the limiting current value in the opposite direction to that during lean operation. The air-fuel ratio can be detected.
【００１８】次に、本発明にかかる空燃比検出装置の前
記ポンプ電圧の異常を診断する実施例について説明す
る。図３は、前記コントロールユニット17による前記ポ
ンプ電圧の異常診断ルーチンの基本的な第１の実施例を
示す。ステップ (図ではＳと記す。以下同様) １では、
燃料供給停止 (燃料カット)中であるか否かを別ルーチ
ンで燃料カット条件成立時に立てられるフラグの値から
判別する。燃料カット条件は、例えば、アクセル開放に
よる減速運転が行われ、かつ、該減速運転開始時の機関
回転速度が所定値以上あるとき等が基本的な条件として
設定される。Next, an embodiment for diagnosing the abnormality of the pump voltage of the air-fuel ratio detecting device according to the present invention will be described. FIG. 3 shows a first basic embodiment of the pump voltage abnormality diagnosis routine by the control unit 17. Step (denoted as S in the figure. The same applies hereinafter) In 1,
Whether or not the fuel supply is stopped (fuel cut) is determined in another routine from the value of the flag set when the fuel cut condition is satisfied. The fuel cut condition is set as a basic condition, for example, when the deceleration operation by opening the accelerator is performed and the engine rotation speed at the start of the deceleration operation is equal to or higher than a predetermined value.
【００１９】ステップ１で燃料カット中であると判定さ
れた場合は、前記空燃比検出装置が正常であってもポン
プ電圧ＶP が正常範囲から外れて異常であるき誤判定さ
れる可能性があるので、診断を行わずステップ５へ進み
空燃検出装置が正常であると診断して、ステップ１に戻
る。即ち、燃料カット中は、燃料供給停止により燃焼が
行われず、大気が排気としてそのまま排出されるため、
広域型空燃比センサの酸素濃度検出部で検出される排気
室と基準ガス室との酸素濃度の差が無くなり検出電極
７，８間の電位差Ｖ1が０近くまで低下し、かつ、排気
温度も大気温度近傍まで下がることによりポンプセル11
の内部抵抗が大きく増大すること等によりポンプ電圧Ｖ
P が異常に増大することがあるので、異常の診断を停止
するのである。If it is determined in step 1 that the fuel is being cut, even if the air-fuel ratio detecting device is normal, the pump voltage V P may be out of the normal range and may be erroneously determined. Therefore, the diagnosis is not performed, and the routine proceeds to step 5, where it is diagnosed that the air-fuel detection device is normal, and the routine returns to step 1. That is, during fuel cut, combustion is not performed due to fuel supply stop, and the atmosphere is exhausted as exhaust gas,
The difference in oxygen concentration between the exhaust chamber and the reference gas chamber detected by the oxygen concentration detector of the wide-range air-fuel ratio sensor disappears, the potential difference V 1 between the detection electrodes 7 and 8 decreases to near 0, and the exhaust temperature also increases. By lowering the temperature to near the ambient temperature, the pump cell 11
Pump voltage V due to a large increase in the internal resistance of
Since P may increase abnormally, the diagnosis of abnormality is stopped.
【００２０】ステップ１で燃料カット中でないと判定さ
れたときは、ステップ２へ進みポンプ電圧｜ＶP ｜が正
常範囲から外れた設定値ＶP0 以上であるか否かを判定
する。そして、｜ＶP ｜≧ＶP0と判定されたときには、
ステップ３で空燃比検出装置に異常があると診断し、該
異常なポンプ電圧ＶP がポンプセル11に印加されるとポ
ンプセル11の耐久性が損なわれるので、ステップ４へ進
んで、広域型空燃比センサを用いた空燃比フィードバッ
ク制御を停止する。｜ＶP ｜＜ＶP0と判定されたときに
は、ステップ５で正常と診断してステップ１に戻る。When it is determined in step 1 that the fuel is not being cut, the routine proceeds to step 2, where it is determined whether or not the pump voltage | V P | is above a set value V P0 outside the normal range. When it is determined that | V P | ≧ V P0 ,
It is diagnosed in step 3 that the air-fuel ratio detecting device has an abnormality, and if the abnormal pump voltage V P is applied to the pump cell 11, the durability of the pump cell 11 is impaired. The air-fuel ratio feedback control using the sensor is stopped. | V P | when it is determined that <V P0, the process returns to step 1 and diagnoses it as normal in step 5.
【００２１】このようにすれば、ポンプセル11への印加
電圧 (ポンプ電圧) の異常診断を、運転状態を要因とし
て一時的に異常値を示す燃料カット時には行わないよう
にしたため、誤判定により空燃比フィードバック制御が
停止されることがなく、リーン運転等による燃費向上を
推進することができる。図４は、ポンプ電圧の異常診断
ルーチンの第２の実施例のフローチャートを示す。In this way, the abnormality of the voltage applied to the pump cell 11 (pump voltage) is not diagnosed at the time of fuel cut that temporarily shows an abnormal value due to the operating state. Therefore, the air-fuel ratio is erroneously determined. The feedback control is not stopped, and it is possible to promote fuel efficiency improvement by lean driving or the like. FIG. 4 shows a flowchart of a second embodiment of the pump voltage abnormality diagnosis routine.
【００２２】ステップ11で燃料カット中か否かを判定
し、燃料カット中と判定されたときにステップ12で空燃
比検出装置が正常と判定することは同様である。ステッ
プ11で燃料カット中でないと判定されたときは、ステッ
プ13へ進んで燃料カット終了後所定時間ｔ0 経過するの
を待ち、所定時間ｔ0 の経過後にステップ14へ進み、前
記同様のポンプ電圧ＶP の異常診断を行い、正常の場合
はステップ12へ進み、異常の場合は異常と診断した後、
ステップ16で空燃比フィードバック制御を停止する。Similarly, it is determined in step 11 whether the fuel is being cut, and when it is determined that the fuel is being cut, the air-fuel ratio detecting device is judged to be normal in step 12. When it is determined not to be in a fuel cut in step 11 waits for a predetermined time t 0 has elapsed after the fuel cut ends proceeds to step 13, the process proceeds to step 14 after a predetermined time t 0, the same pump voltage After diagnosing V P abnormality, if it is normal, proceed to step 12. If it is abnormal, diagnose it as abnormal,
At step 16, the air-fuel ratio feedback control is stopped.
【００２３】即ち、燃料カット停止後も暫くの間は排気
通路中に残存する大気が広域型空燃比センサに導かれて
検出され、ポンプセル11が燃焼排気によって通常温度ま
で上昇するのにも時間遅れがあるため、該遅れ時間分は
診断を停止するようにしたものである。図５は、第２実
施例と同様の主旨に基づくポンプ電圧の異常診断ルーチ
ンの第３の実施例のフローチャートを示す。That is, for a while after the fuel cut is stopped, the atmosphere remaining in the exhaust passage is guided to and detected by the wide area air-fuel ratio sensor, and there is a time delay before the pump cell 11 rises to the normal temperature by the combustion exhaust. Therefore, the diagnosis is stopped for the delay time. FIG. 5 shows a flowchart of a third embodiment of a pump voltage abnormality diagnosis routine based on the same concept as in the second embodiment.
【００２４】このものでは、ステップ21で燃料カット中
と判定されたときに、ステップ22で燃料カット開始後の
時間Ｔを計測した後ステップ23で正常との診断を行い、
燃料カット終了後にステップ24で前記燃料カットの継続
時間Ｔに応じて燃料カット終了後の異常診断停止時間ｔ
1 を設定する。そして、ステップ25で燃料カット終了後
前記設定された異常診断停止時間ｔ1の経過を待ってス
テップ26のポンプ電圧ＶP の異常診断を行い、正常の場
合はステップ23へ進み、異常の場合は、ステップ27で異
常と診断した後、ステップ28で空燃比フィードバック制
御を停止する。In this device, when it is determined in step 21 that the fuel is being cut, the time T after the fuel cut is started is measured in step 22 and then a normal diagnosis is made in step 23.
After the fuel cut, in step 24, the abnormality diagnosis stop time t after the fuel cut is finished according to the fuel cut duration T.
Set to 1 . Then, in step 25, after the completion of the fuel cut, the set abnormality diagnosis stop time t 1 is waited for, and the abnormality diagnosis of the pump voltage V P is performed in step 26. If the abnormality is normal, the routine proceeds to step 23, and if abnormal, After diagnosing the abnormality in step 27, the air-fuel ratio feedback control is stopped in step 28.
【００２５】このようにすれば、燃料カット継続時間が
長いほど大気による広域型空燃比センサの温度低下が大
きく燃料カット終了後の温度回復に時間を要するので、
それだけ異常診断停止時間ｔを長く設定することにより
必要かつ十分な時間だけ診断を停止することができる。
図６は、前記第３の実施例と同様の主旨に基づくポンプ
電圧の異常診断ルーチンの第４の実施例のフローチャー
トを示す。In this way, the longer the fuel cut duration is, the greater the temperature drop of the wide area type air-fuel ratio sensor due to the atmosphere becomes, and it takes time to recover the temperature after the fuel cut.
By setting the abnormality diagnosis stop time t as long as that, the diagnosis can be stopped for a necessary and sufficient time.
FIG. 6 shows a flow chart of a fourth embodiment of a pump voltage abnormality diagnosis routine based on the same concept as in the third embodiment.
【００２６】ステップ31で燃料カット中と判定されたと
きにはステップ32で燃料カット開始時の機関回転速度Ｎ
0 を読み込んでからステップ33で正常と診断し、燃料カ
ット終了後にステップ34で前記機関回転速度Ｎ0 に基づ
いて燃料カット終了後の異常診断停止時間ｔ2 を設定す
る。そして、ステップ35で燃料カット終了後前記設定さ
れた異常診断停止時間ｔ2の経過を待ってステップ36の
ポンプ電圧ＶP の異常診断を行い、正常の場合はステッ
プ33へ進み、異常の場合はステップ37で異常と診断した
後、ステップ38で空燃比フィードバック制御を停止す
る。When it is determined in step 31 that fuel is being cut, in step 32 the engine speed N at the start of fuel cutting
After reading 0 , it is diagnosed as normal in step 33, and after the fuel cut is completed, the abnormal diagnosis stop time t 2 after the fuel cut is set based on the engine speed N 0 in step 34. Then, in step 35, after the completion of the fuel cut, the set abnormality diagnosis stop time t 2 is waited for, and the abnormality of the pump voltage V P in step 36 is diagnosed. If the abnormality is normal, the routine proceeds to step 33, and if abnormal, After diagnosing the abnormality in step 37, the air-fuel ratio feedback control is stopped in step 38.
【００２７】このようにすれば、前記燃料カット時間は
機関回転速度が所定回転速度以下になるまで行われるの
で、燃料カット開始時の機関回転速度が高速であるほ
ど、燃料供給が再開される所定回転速度との差が大きい
ため燃料カット時間が長引くことになるので、燃料カッ
ト時間を計測しなくても燃料カット開始時の機関回転速
度に基づいて燃料カット時間を推定して燃料供給再開後
の異常診断停止時間を設定することができる。In this way, the fuel cut time is continued until the engine rotation speed becomes equal to or lower than the predetermined rotation speed. Therefore, the higher the engine rotation speed at the start of the fuel cut, the more the fuel supply is restarted. Since the difference with the rotation speed is large, the fuel cut time will be prolonged.Therefore, even if the fuel cut time is not measured, the fuel cut time is estimated based on the engine rotation speed at the start of fuel cut and Abnormal diagnosis stop time can be set.
【００２８】尚、以上の実施例では、基本的に燃料カッ
ト時にポンプ電圧の異常診断を停止するものについて示
したが、リーンの度合いが大きい運転状態で、かつ、排
気温度が特に低いような運転状態においても診断を停止
するような構成としてもよい。In the above embodiment, the pump voltage abnormality diagnosis is basically stopped when the fuel is cut off. However, in the operating state where the degree of lean is large and the exhaust temperature is particularly low. The diagnosis may be stopped even in the state.
【００２９】[0029]
【発明の効果】以上説明してきたように請求項１の発明
によると、機関の運転状態の要因で広域型空燃比センサ
の第２の電極間に印加される電圧が一時的に異常となる
ときには、該印加電圧の異常の診断を停止することによ
り誤判定を防止でき、以て広域型空燃比センサを用いた
リーン運転等の空燃比制御を推進でき、燃費等の向上を
図れる。As described above, according to the invention of claim 1, when the voltage applied between the second electrodes of the wide area type air-fuel ratio sensor becomes temporarily abnormal due to the operating state of the engine. The erroneous determination can be prevented by stopping the diagnosis of the abnormality of the applied voltage, and thus the air-fuel ratio control such as the lean operation using the wide area type air-fuel ratio sensor can be promoted, and the fuel consumption can be improved.
【００３０】請求項２の発明によると、燃料供給停止時
は大気が排出されるため第２の電極間に印加される電圧
が最も異常な値となりやすい運転状態であるので、該燃
料停止時に異常診断を停止することにより、異常の診断
精度が向上する。請求項３の発明によると、前記燃料供
給停止終了後も排気通路中に大気が残存することによる
誤判定を避けるため、所定時間が経過するまで異常診断
を停止することにより、診断精度をより向上できる。According to the second aspect of the present invention, since the atmosphere is discharged when the fuel supply is stopped, the voltage applied between the second electrodes tends to be the most abnormal value. Stopping the diagnosis improves the accuracy of the abnormality diagnosis. According to the invention of claim 3, in order to avoid erroneous determination due to air remaining in the exhaust passage even after the fuel supply is stopped, the abnormality diagnosis is stopped until a predetermined time elapses, thereby further improving the diagnostic accuracy. it can.
【００３１】請求項４の発明によると、燃料供給停止時
間に応じて燃料供給再開後の異常診断停止時間を必要か
つ十分な時間に設定できる。請求項５の発明によると、
前記燃料供給停止開始時の機関回転速度に基づいて燃料
供給停止時間を推定して燃料供給再開後の異常診断停止
時間を設定することができる。According to the invention of claim 4, the abnormality diagnosis stop time after the fuel supply is restarted can be set to a necessary and sufficient time according to the fuel supply stop time. According to the invention of claim 5,
The fuel supply stop time can be estimated based on the engine speed at the start of the fuel supply stop to set the abnormality diagnosis stop time after the fuel supply is restarted.
【図１】本発明の構成・機能を示すブロック図。FIG. 1 is a block diagram showing the configuration and functions of the present invention.
【図２】本発明の一実施例の構成を示す回路図。FIG. 2 is a circuit diagram showing a configuration of an embodiment of the present invention.
【図３】本発明の第１の実施例に係る異常診断ルーチン
のフローチャート。FIG. 3 is a flowchart of an abnormality diagnosis routine according to the first embodiment of the present invention.
【図４】本発明の第２の実施例に係る異常診断ルーチン
のフローチャート。FIG. 4 is a flowchart of an abnormality diagnosis routine according to a second embodiment of the present invention.
【図５】本発明の第３の実施例に係る異常診断ルーチン
のフローチャート。FIG. 5 is a flowchart of an abnormality diagnosis routine according to a third embodiment of the present invention.
【図６】本発明の第４の実施例に係る異常診断ルーチン
のフローチャート。FIG. 6 is a flowchart of an abnormality diagnosis routine according to a fourth embodiment of the present invention.
【図７】広域型空燃比センサのポンプ電圧の各種要因に
基づく特性を示す図。FIG. 7 is a diagram showing characteristics of a wide range air-fuel ratio sensor based on various factors of pump voltage.
４ 基準ガス室 ５ 酸素濃度検出部 ６ 第１の酸素イオン伝導性固体電解質 ７ 検出電極 ８ 検出電極 ９ 排気室 10 酸素ポンプ部 11 第２の酸素イオン伝導性固体電解質 12 ポンプ電極 13 ポンプ電極 15 増幅器 16 電流検出用抵抗 17 コントロールユニット 4 Reference gas chamber 5 Oxygen concentration detection unit 6 First oxygen ion conductive solid electrolyte 7 Detection electrode 8 Detection electrode 9 Exhaust chamber 10 Oxygen pump unit 11 Second oxygen ion conductive solid electrolyte 12 Pump electrode 13 Pump electrode 15 Amplifier 16 Current detection resistor 17 Control unit
───────────────────────────────────────────────────── フロントページの続き (72)発明者 森田 徳英 神奈川県横浜市神奈川区宝町２番地 日産 自動車株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tokuhide Morita 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.
Claims (5)
で両側に基準酸素濃度を有する基準ガスが導かれる基準
ガス室と内燃機関の排気通路中の排気が導かれる排気室
とを備え、該第１の酸素イオン伝導性固体電解質の基準
ガス室と排気室とに面する両面に夫々設けられた第１の
電極間に前記両室の酸素濃度比に応じた電位差を発生す
る酸素濃度検出部と、前記排気室と排気通路との間を排
気の導入孔を残して大略覆う第２の酸素イオン伝導性固
体電解質の排気通路側と排気室側とに面する両面に夫々
設けられた第２の電極間に電圧を印加されることにより
排気通路と排気室との間で第２の酸素イオン伝導性固体
電解質を介して酸素イオンを輸送する酸素ポンプ部と、
を備えてなる広域型空燃比センサと、 前記酸素濃度検出部で検出される両室の酸素濃度比に応
じた電圧を印加して酸素ポンプ部で酸素イオンを輸送さ
せるセンサ制御回路と、 からなり、前記酸素イオン輸送時に第２の電極間に流れ
る電流値によって排気中の酸素濃度を検出し、以て機関
吸入混合気の空燃比を検出するように構成された内燃機
関の空燃比検出装置において、 機関の運転状態の要因によって前記第２の電極間に印加
される電圧が正常範囲から外れる所定の運転状態を検出
する所定運転状態検出手段と、 前記第２の電極間に印加される電圧の異常の有無を、前
記所定の運転状態以外の運転状態のときに診断する異常
診断手段を設けたことを特徴とする内燃機関における広
域型空燃比センサの異常診断装置。1. A reference gas chamber into which a reference gas having a reference oxygen concentration is introduced, and an exhaust chamber into which exhaust gas in an exhaust passage of an internal combustion engine is introduced are provided on both sides of a first oxygen ion conductive solid electrolyte. Oxygen concentration detection for generating a potential difference according to the oxygen concentration ratio of both chambers between the first electrodes provided on both sides of the first oxygen ion conductive solid electrolyte facing the reference gas chamber and the exhaust chamber. And a second oxygen ion conductive solid electrolyte, which substantially covers the space between the exhaust chamber and the exhaust passage, leaving an introduction hole for the exhaust, and is provided on both surfaces facing the exhaust passage side and the exhaust chamber side, respectively. An oxygen pump unit that transports oxygen ions through the second oxygen ion conductive solid electrolyte between the exhaust passage and the exhaust chamber by applying a voltage between the two electrodes;
A wide-range air-fuel ratio sensor, and a sensor control circuit that applies a voltage according to the oxygen concentration ratio of both chambers detected by the oxygen concentration detection unit to transport oxygen ions by the oxygen pump unit. In an air-fuel ratio detection device for an internal combustion engine, which is configured to detect the oxygen concentration in exhaust gas by the value of a current flowing between the second electrodes during the transport of oxygen ions, and thus to detect the air-fuel ratio of the engine intake air-fuel mixture. A predetermined operating state detecting means for detecting a predetermined operating state in which a voltage applied between the second electrodes is out of a normal range due to a factor of an operating state of the engine; and a voltage applied between the second electrodes. An abnormality diagnosing device for a wide area type air-fuel ratio sensor in an internal combustion engine, comprising an abnormality diagnosing means for diagnosing the presence or absence of an abnormality in an operating state other than the predetermined operating state.
料の供給が停止される運転状態を前記所定の運転状態と
して検出することを特徴とする請求項１に記載の内燃機
関における広域型空燃比センサの異常診断装置。2. The wide area type internal combustion engine according to claim 1, wherein the predetermined operation state detecting means detects an operation state in which the supply of fuel to the engine is stopped as the predetermined operation state. Air-fuel ratio sensor abnormality diagnosis device.
関への燃料の供給が停止される運転状態の終了後も所定
時間継続して、前記所定の運転状態として検出すること
を特徴とする請求項２に記載の内燃機関における広域型
空燃比センサの異常診断装置。3. The predetermined operating state detecting means detects the predetermined operating state by continuing for a predetermined time even after the end of the operating state in which the supply of fuel to the internal combustion engine is stopped. An abnormality diagnosis device for a wide area type air-fuel ratio sensor in an internal combustion engine according to claim 2.
供給が停止される運転状態の継続時間に応じて設定され
ることを特徴とする請求項３に記載の内燃機関における
広域型空燃比センサの異常検出装置。4. The wide area type empty space in an internal combustion engine according to claim 3, wherein the predetermined time is set according to a duration of an operating state in which the supply of fuel to the internal combustion engine is stopped. Abnormality detection device for fuel ratio sensor.
運転状態の継続時間を燃料供給停止開始時の機関回転速
度によって推定して前記所定時間を設定することを特徴
とする請求項４に記載の内燃機関における広域型空燃比
センサの異常検出装置。5. The predetermined time is set by estimating the duration of an operating state in which the supply of fuel to the internal combustion engine is stopped based on the engine rotation speed at the start of the stop of fuel supply. A wide range air-fuel ratio sensor abnormality detection device for an internal combustion engine according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32340194A JP3314567B2 (en) | 1994-12-26 | 1994-12-26 | Air-fuel ratio detection device abnormality diagnosis device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32340194A JP3314567B2 (en) | 1994-12-26 | 1994-12-26 | Air-fuel ratio detection device abnormality diagnosis device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08178896A true JPH08178896A (en) | 1996-07-12 |
| JP3314567B2 JP3314567B2 (en) | 2002-08-12 |
Family
ID=18154309
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32340194A Expired - Fee Related JP3314567B2 (en) | 1994-12-26 | 1994-12-26 | Air-fuel ratio detection device abnormality diagnosis device |
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| Country | Link |
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| JP (1) | JP3314567B2 (en) |
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| JP2002257772A (en) * | 2001-02-27 | 2002-09-11 | Ngk Spark Plug Co Ltd | Abnormality detecting method for air-fuel ratio sensor and protecting method for sensor control circuit |
| US7320746B2 (en) | 2003-08-20 | 2008-01-22 | Toyota Jidosha Kabushiki Kaisha | Concentration detector |
| WO2015029166A1 (en) * | 2013-08-28 | 2015-03-05 | トヨタ自動車株式会社 | Control device for internal combustion engine |
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| JP2002257772A (en) * | 2001-02-27 | 2002-09-11 | Ngk Spark Plug Co Ltd | Abnormality detecting method for air-fuel ratio sensor and protecting method for sensor control circuit |
| US7320746B2 (en) | 2003-08-20 | 2008-01-22 | Toyota Jidosha Kabushiki Kaisha | Concentration detector |
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| JP5858178B2 (en) * | 2013-08-28 | 2016-02-10 | トヨタ自動車株式会社 | Control device for internal combustion engine |
| CN105473840A (en) * | 2013-08-28 | 2016-04-06 | 丰田自动车株式会社 | Control device for internal combustion engine |
| CN105473840B (en) * | 2013-08-28 | 2018-04-24 | 丰田自动车株式会社 | The control device of internal combustion engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3314567B2 (en) | 2002-08-12 |
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