JP3764842B2 - Heater control device for air-fuel ratio sensor - Google Patents

Heater control device for air-fuel ratio sensor Download PDF

Info

Publication number
JP3764842B2
JP3764842B2 JP2000147165A JP2000147165A JP3764842B2 JP 3764842 B2 JP3764842 B2 JP 3764842B2 JP 2000147165 A JP2000147165 A JP 2000147165A JP 2000147165 A JP2000147165 A JP 2000147165A JP 3764842 B2 JP3764842 B2 JP 3764842B2
Authority
JP
Japan
Prior art keywords
target temperature
air
temperature
fuel ratio
ratio sensor
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
Application number
JP2000147165A
Other languages
Japanese (ja)
Other versions
JP2001330583A (en
Inventor
肇 細谷
太 一柳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP2000147165A priority Critical patent/JP3764842B2/en
Priority to DE2001124134 priority patent/DE10124134A1/en
Publication of JP2001330583A publication Critical patent/JP2001330583A/en
Application granted granted Critical
Publication of JP3764842B2 publication Critical patent/JP3764842B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1493—Details
    • F02D41/1494—Control of sensor heater
    • 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
    • G01N27/4067—Means for heating or controlling the temperature of the solid electrolyte

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • Immunology (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Electrochemistry (AREA)
  • Pathology (AREA)
  • Molecular Biology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Measuring Oxygen Concentration In Cells (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、内燃機関の排気系に装着されて空燃比制御に用いられる、センサ素子加熱用のヒータを備える空燃比センサ（酸素センサを含む）のヒータ制御装置に関する。
【０００２】
【従来の技術】
内燃機関の空燃比制御装置として、空燃比センサにより排気中の酸素濃度などに基づいて実際の空燃比を検出し、これが目標空燃比となるように、機関への燃料供給量をフィードバック制御するものが知られている。
【０００３】
ところで、上記の空燃比フィードバック制御を行うためには、空燃比センサが活性化していることが前提条件となり、空燃比センサは、その素子温度が所定の活性温度に達することで活性化されるため、空燃比センサには、センサ素子加熱用のヒータを装備させて、ヒータへの通電制御により素子温度を目標温度に制御している（例えば特開平７−１９８６７９号公報、特開平８−２７８２７９号公報参照）。
【０００４】
具体的には、センサ素子の内部抵抗を計測して、これより推定される素子温度に基づき、これが目標温度となるように、ヒータへの通電量をフィードバック制御している。
【０００５】
【発明が解決しようとする課題】
ところで、ヒータでの消費電力を低減させる目的からは、空燃比センサの素子温度の目標温度は、活性温度範囲の下限（例えば３５０℃）付近に低く押さえた方がよい。
【０００６】
しかるに、空燃比センサの素子温度を下げると、素子が短時間で被毒してしまい、被毒によりセンサ出力の反転周期が長くなり、空燃比制御性能が低下してしまう。
【０００７】
すなわち、図８に示すように、センサ素子の被毒状態では、リッチ→リーンの素子の応答性が低下し、その結果、空燃比制御系出力がリッチ側にシフトし、排気性能や燃費性能が低下してしまうのである。
【０００８】
本発明は、このような従来の問題点に鑑み、センサ素子の被毒を解消しつつ、可能な限りヒータでの消費電力を節減することを目的とする。
【０００９】
【課題を解決するための手段】
このため、請求項１に係る発明では、図１に示すように、空燃比センサの素子温度を計測して、目標温度となるように、空燃比センサに備えられるヒータへの通電量を制御する空燃比センサのヒータ制御装置において、空燃比センサ出力の反転回数を計測する手段を有し、計測された反転回数に従って、前記目標温度を低温側目標温度と高温側目標温度とに交互に切換える目標温度切換手段を設けたことを特徴とする。
【００１０】
ここで、低温側目標温度は、センサ素子の活性温度範囲での下限付近の温度であって、センサ素子が被毒する可能性がある温度である。高温側目標温度は、センサ素子が被毒から回復可能な温度である。
【００１１】
より具体的には、請求項２に係る発明のように、前記目標温度切換手段は、空燃比センサ出力の反転回数が第１の所定値に達するまでの間、目標温度を低温側目標温度に設定し、この後、空燃比センサ出力の反転回数が第２の所定値に達するまでの間、目標温度を高温側目標温度に設定する。
【００１２】
また、請求項３に係る発明では、図１に示すように、空燃比センサの素子温度を計測して、目標温度となるように、空燃比センサに備えられるヒータへの通電量を制御する空燃比センサのヒータ制御装置において、空燃比センサ出力の反転周期を計測する手段を有し、計測された反転周期が第１の所定値以上となった時点で前記目標温度を低温側目標温度から高温側目標温度に切換え、その後、計測された反転周期が前記第１の所定値より小さく設定された第２の所定値以下となった時点で前記目標温度を高温側目標温度から低温側目標温度に切換えることによって、前記目標温度を低温側目標温度と高温側目標温度とに交互に切換える目標温度切換手段を設けたことを特徴とする。
【００１３】
請求項４に係る発明では、空燃比センサの素子温度計測手段として、空燃比センサのセンサ素子に素子温度計測用の所定の電圧を一時的に印加する素子温度計測用電圧印加手段と、前記電圧印加中のセンサ出力に基づいてセンサ素子の内部抵抗を算出する内部抵抗算出手段と、算出された内部抵抗に基づいて素子温度を算出する素子温度算出手段とを備えることを特徴とする。
【００１４】
【発明の効果】
請求項１〜４に係る発明によれば、ヒータへの通電量制御による空燃比センサの素子温度制御に際し、目標温度を低温側目標温度と高温側目標温度とに交互に切換えることで、低温側目標温度にてヒータ消費電力の節減を図る一方、このときに被毒しても、高温側目標温度にて被毒から回復させることができ、センサ素子の被毒を解消しつつ、可能な限りヒータ消費電力を節減することができる。
【００１５】
特に請求項１、２に係る発明によれば、空燃比センサ出力の反転周期は概ね一定であることを利用し、センサ出力の反転回数を計測して、計測された反転回数に従って、目標温度を低温側目標温度と高温側目標温度とに切換えることで、より具体的には、目標温度を低温側目標温度に設定した状態で、センサ出力の反転回数が第１の所定値に達したときに、被毒とみなして、目標温度を高温側目標温度に切換え、この状態でセンサ出力の反転回数が第２の所定値に達したときに、被毒解除とみなして、目標温度を低温側目標温度に戻すことで、簡潔な制御を実現できる。
【００１６】
特に請求項３に係る発明によれば、被毒により空燃比センサ出力の反転周期が長くなることから、センサ出力の反転周期を計測して、これに基づいて、目標温度を低温側目標温度と高温側目標温度とに切換えることで、すなわち、被毒有りと判定されたときに、目標温度を高温側目標温度に設定することで、被毒の影響を直接的に監視でき、内燃機関の使用環境や燃料性状等によりセンサ素子被毒に至る時間のバラツキがある場合に、最適制御により、ヒータ消費電力の節減と被毒解消による制御性能向上とを高次元で両立できる。
【００１７】
特に請求項４に係る発明によれば、素子温度計測に際し、空燃比センサのセンサ素子に素子温度計測用の所定の電圧を一時的に印加し、このときのセンサ出力に基づいてセンサ素子の内部抵抗を算出し、この内部抵抗に基づいて素子温度を算出することで、素子温度を的確に計測（推定）することが可能となる。
【００１８】
【発明の実施の形態】
以下に本発明の実施の形態について説明する。
図２は内燃機関の空燃比フィードバック制御装置のシステム図である。
【００１９】
内燃機関（以下エンジンという）１には、各気筒毎に、吸気通路２又は燃焼室内に臨むように、燃料噴射弁３が設けられ、各燃料噴射弁３の燃料噴射はコントロールユニット４により制御される。
【００２０】
コントロールユニット４は、例えば、エアフローメータ５からの信号に基づいて検出される吸入空気量Ｑａと、クランク角センサ６からの信号に基づいて検出されるエンジン回転数Ｎｅとから、ストイキ（λ＝１）相当の基本燃料噴射量Ｔｐ＝Ｋ×Ｑａ／Ｎｅ（Ｋは定数）を演算し、これを目標空燃比ｔλの他、排気通路７に配置した空燃比センサ８からの信号に基づく空燃比フィードバック補正係数αにより補正して、最終的な燃料噴射量Ｔｉ＝Ｔｐ×（１／ｔλ）×αを演算し、このＴｉに対応するパルス幅の燃料噴射パルスを、エンジン回転に同期して、各燃料噴射弁３に出力する。
【００２１】
ここで、空燃比センサ８は、排気通路７に配置されて、排気中の酸素濃度に応じた信号を出力するもので、コントロールユニット４は、空燃比センサ８からの信号に基づいて、エンジン１に供給されている混合気の空燃比λを検出し、これが目標空燃比ｔλとなるように、空燃比フィードバック補正係数αを比例積分制御などにより増減設定することで、空燃比λを目標空燃比ｔλにフィードバック制御する。
【００２２】
また、空燃比センサ８としては、空燃比に応じて出力電圧が連続的に変化することで空燃比をリニアに検出可能ないわゆる広域型空燃比センサであって、図３に示すようにセンサ素子１１加熱用のヒータ１２を備えるものを用いる。
【００２３】
図３は空燃比センサ８のセンサ素子１１及びセンサ素子加熱用のヒータ１２に対する制御回路を示している。
空燃比センサ８のセンサ素子１１は、空燃比に応じて出力電圧Ｖｓが連続的に変化し、その出力Ｖｓはコントロールユニット４に入力される。
【００２４】
また、センサ素子１１には、素子温度計測用（内部抵抗計測用）の所定の電圧Ｖcc（例えば５Ｖ）がスイッチング素子１３及び基準抵抗Ｒ０を介して印加されるようになっている。従って、素子温度計測時に、スイッチング素子１３がＯＮとなると、センサ素子１１の出力Ｖｓに素子温度計測用の電圧分が重畳される。
【００２５】
ヒータ１２には、バッテリ電圧ＶＢを印加するが、通電回路中にスイッチング素子１４を設けてある。
コントロールユニット４内のＣＰＵ１５は、素子温度計測用電圧印加用のスイッチング素子１３のＯＮ・ＯＦＦを制御しつつ、所定のタイミングで、センサ素子１１の出力Ｖｓをフィルタ（平滑化回路）１６及びＡ／Ｄ変換器１７を介して読込む。
【００２６】
また、ＣＰＵ１５は、Ｄ／Ａ変換器１８を介して、ヒータ制御用のスイッチング素子１４のＯＮ・ＯＦＦをデューティ制御することにより、ヒータ１２への通電量を制御する。
【００２７】
次にＣＰＵ１５の制御内容をフローチャートにより説明する。
図４は素子温度計測ルーチンのフローチャートであり、所定のクランク角周期で実行される。本ルーチンが素子温度計測手段に相当する。
【００２８】
ステップ１（図にはＳ１と記す。以下同様）では、空燃比を検出すべく、センサ出力Ｖｓを読込み、Ｖaf＝Ｖｓとして、これに基づいて空燃比λを検出する。
ステップ２では、スイッチング素子１３をＯＮにして、センサ素子１１への素子温度計測用電圧Ｖccの印加を開始する。すなわち、空燃比検出用のセンサ出力の読込み直後より、素子温度計測用電圧Ｖccの印加を開始する。この部分が素子温度計測用電圧印加手段に相当する。
【００２９】
ステップ３では、素子温度計測用電圧の印加開始から所定時間後に、センサ素子１１の内部抵抗を計測すべく、センサ出力Ｖｓを読込み、Ｖｒ＝Ｖｓとする。
ステップ４では、電圧印加中のセンサ出力Ｖｒを電圧印加直前のセンサ出力Ｖafにより補正する。具体的には、電圧印加中のセンサ出力Ｖｒから電圧印加直前のセンサ出力Ｖafを減算して、補正後センサ出力Ｖｒ＝Ｖｒ−Ｖafを求める。
【００３０】
ステップ５では、補正後センサ出力Ｖｒに基づいて、センサ素子１１の内部抵抗Ｒｓを算出する。この部分が内部抵抗算出手段に相当する。
具体的には、センサ素子１１に流れる電流をｉとし、Ｖｓ＝Ｖｒとすると、
Ｖｒ＝ｉ×Ｒｓ
Ｖcc−Ｖｒ＝ｉ×Ｒ０
であるので、両式より、
Ｒｓ＝Ｖｒ／〔（Ｖcc−Ｖｒ）／Ｒ０〕
として、内部抵抗Ｒｓを算出する。
【００３１】
ステップ６では、センサ素子１１の内部抵抗Ｒｓより、テーブルを参照するなどして、素子温度Ｔｓを算出する。素子温度Ｔｓが高くなるほど、内部抵抗Ｒｓが減少するので、内部抵抗Ｒｓより、素子温度Ｔｓを算出可能だからである。この部分が素子温度算出手段に相当する。
【００３２】
ステップ７では、素子温度計測用電圧の印加開始から所定時間後に、スイッチング素子１３をＯＦＦにすることで、センサ素子１１への素子温度計測用電圧Ｖccの印加を停止（終了）する。
【００３３】
図５はヒータ制御ルーチンのフローチャートであり、通常運転中に所定時間毎に実行される。本ルーチンがヒータ通電量制御手段に相当する。
ステップ１１では、図４のルーチンにより算出されている最新の素子温度Ｔｓを読込む。
【００３４】
ステップ１２では、後述する図６又は図７のルーチンにより設定される目標温度（低温側目標温度ＴＬ又は高温側目標温度ＴＨ）を読込む。
ステップ１３では、実際の素子温度Ｔｓと目標温度との偏差に応じて、周知のＰＩＤ制御により、素子温度Ｔｓを目標温度に近づけるように、ヒータデューティＨＤＵＴＹ（％）を算出する。
【００３５】
具体的には、実際の素子温度Ｔｓが目標温度より低い場合は、ヒータ１２への通電量（通電時間割合）を増大させるように、ヒータデューティＨＤＵＴＹを増大させ、逆に、実際の素子温度Ｔｓが目標温度より高い場合は、ヒータ１２への通電量（通電時間割合）を減少させるように、ヒータデューティＨＤＵＴＹを減少させる。
【００３６】
ステップ１４では、算出されたヒータデューティＨＤＵＴＹを出力し、これによりスイッチング素子１４のＯＮ・ＯＦＦでヒータ１２への通電量を制御して、素子温度Ｔｓを目標温度に収束させる。
【００３７】
ここにおいて、本発明では、ヒータ１２への通電量制御による空燃比センサ８の素子温度のフィードバック制御に際し、目標温度を、低温側目標温度ＴＬと高温側目標温度ＴＨとに交互に切換える。時間割合で見れば、基本的には低温側目標温度ＴＬに設定し、一時的に高温側目標温度ＴＨに切換える。
【００３８】
ここでいう低温側目標温度ＴＬとは、空燃比センサの活性温度範囲での下限付近の温度（例えば３５０℃）であって、センサ素子の被毒の可能性のある温度である。また、高温側目標温度ＴＨとは、センサ素子の被毒を解消可能な温度である（例えば７５０℃）。
【００３９】
図６は第１実施形態での目標温度設定ルーチンのフローチャートである。本ルーチンが目標温度切換手段に相当する。
【００４０】
ステップ３１では、先ず、目標温度を低温側目標温度ＴＬ（例えば３５０℃）に設定する。
そして、ステップ３２では、目標温度を低温側目標温度ＴＬに設定した状態での、センサ出力の反転回数を計測し（センサ出力反転回数計測手段）、ステップ３３では、反転回数が第１の所定値Ａ以上となったか否かを判定する。
【００４１】
第１の所定値Ａ未満であれば、目標温度を低温側目標温度ＴＬに維持して、反転回数の計測を続け、第１の所定値Ａに達した時点で、ステップ３４へ進む。
ステップ３４では、目標温度をセンサ素子が被毒から回復可能な高温側目標温度ＴＨ（例えば７５０℃）に切換える。
【００４２】
そして、ステップ３５では、目標温度を高温側目標温度ＴＨに設定した状態での、センサ出力の反転回数を計測し（センサ出力反転回数計測手段）、ステップ３６では、反転回数が第２の所定値Ｂ以上となったか否かを判定する。Ｂ＜Ａである。
【００４３】
第２の所定値Ｂ未満であれば、目標温度を高温側目標温度ＴＨに維持して、反転回数の計測を続け、第２の所定値Ｂに達した時点で、ステップ３１へ戻り、再び目標温度を低温側目標温度ＴＬに切換える。
【００４４】
このように、ヒータ１２への通電量制御による空燃比センサ８の素子温度のフィードバック制御に際し、目標温度をタイムスケジュール（センサ出力の反転回数）に従って交互に切換え、可能な限り目標温度を低温側目標温度ＴＬに設定して、ヒータ１２での消費電力の節減を図る一方、低温側目標温度ＴＬでは被毒の可能性があるので、低温側目標温度ＴＬでセンサ出力の反転回数が第１の所定値Ａに達したときに、一時的に（センサ出力の反転回数が第２の所定値Ｂに達するまでの間）、目標温度を高温側目標温度ＴＨに切換えて、被毒からの回復を図るのである。
【００４５】
すなわち、この第１実施形態は、空燃比センサのセンサ出力の反転周期は概ね一定であることを利用し、センサ出力の反転回数のカウント値に基づいてタイムスケジュールを規定するようにしたものである。尚、前記第１の所定値Ａは概ね時間オーダーに相当するのに対し、前記第２の所定値Ｂは概ね分オーダーに相当するものである（Ｂ＜Ａ）。
【００４６】
従って、ヒータ１２での消費電量を最小限に押さえつつ、センサ素子の被毒による影響を回避することができる。
【００４７】
尚、空燃比センサの被毒及び被毒解除のメカニズムは、次の通りである。
（１）被毒のメカニズム
大気やオイルに含まれているＳｉＯ2 、活性Ｓｉ、活性Ｐ、活性Ｚｒ等が、排気ガスを通じて、センサ素子表面（ジルコニア上のＰｔ電極を覆う保護層の表面）に付着する。その後、保護層の中に入り、保護層を目詰まりさせることで、ガス透過性を低下させたり、更にはＰｔ電極に達して付着することにより、Ｐｔ電極表面上でのＯ2 イオンの移動を阻害したりする。
【００４８】
（２）被毒解除のメカニズム
素子温度を７５０℃以上に高くすると、素子に付着していた活性Ｓｉや活性Ｐ等の活性化エネルギーが増えるため、これらが保護層やＰｔ電極に付着していられなくなり、飛び去ってしまう。
【００４９】
次に本発明の他の実施形態について説明する。
図７は第２実施形態での目標温度設定ルーチンのフローチャートであり、図６のフローに代えて実行される。本ルーチンが目標温度切換手段に相当する。
ステップ４１では、先ず、目標温度を低温側目標温度ＴＬに設定する。
【００５０】
そして、ステップ４２では、目標温度を低温側目標温度ＴＬに設定した状態での、センサ出力の反転周期を計測し、ステップ４３では、反転周期が第１の所定値Ａ以上となったか否かを判定する。
【００５１】
第１の所定値Ａ未満であれば、目標温度を低温側目標温度ＴＬに維持して、反転周期の計測を続け、第１の所定値Ａ以上となった時点で、被毒とみなして、ステップ４４へ進む。
【００５２】
ステップ４４では、目標温度をセンサ素子が被毒から回復可能な高温側目標温度ＴＨに切換える。
そして、ステップ４５では、目標温度を高温側目標温度ＴＨに設定した状態での、センサ出力の反転周期を計測し、ステップ４６では、反転周期が第２の所定値Ｂ以下となったか否かを判定する。第２の所定値Ｂは、第１の所定値Ａに対しヒステリシスを付けたもので、第１の所定値Ａよりヒステリシス分小さく設定される。
【００５３】
第２の所定値Ｂを超えていれば、目標温度を高温側目標温度ＴＨに維持して、反転周期の計測を続け、第２の所定値Ｂ以下となった時点で、被毒解除とみなして、ステップ４１へ戻り、再び目標温度を低温側目標温度ＴＬに切換える。
【００５４】
ここで、ステップ４２，４５の部分がセンサ出力反転周期計測手段に相当し、ステップ４３，４６の部分が被毒判定手段に相当する。
この第２実施形態は、空燃比センサが被毒すると、図８に示すように、リッチ→リーンの素子の応答性が低下し、センサ出力の反転周期ＴRVが長くなることから、反転周期を計測して、所定値未満であれば，被毒無しと判定して、低温側目標温度ＴＬに設定することで、ヒータ消費電力の節減を図り、所定値以上であれば、被毒有りと判定して、高温側目標温度ＴＨに切換えることで、被毒からの回復を図るのである。
【００５５】
素子温度の目標温度設定をタイムスケジュール設定で行った場合は、エンジンの使用環境やガソリン性状等による素子被毒に至る時間のバラツキを考慮して、低温設定時間を短めに、高温設定時間を長めにしなければないが、この第２実施形態では、素子被毒の影響を直接的に監視するため、上述のマージンは不要であるため、ヒータ消費電力をより節減することが可能となる。
【００５６】
尚、被毒判定のための反転周期としては、図８の反転周期ＴRVの他、リッチ→リーンの反転周期ＴRLを計測してもよい。
【図面の簡単な説明】
【図１】 本発明の構成を示す機能ブロック図
【図２】 本発明の実施形態を示すエンジンの空燃比フィードバック制御装置のシステム図
【図３】 空燃比センサのセンサ素子及びヒータに対する制御回路図
【図４】 素子温度計測ルーチンのフローチャート
【図５】 ヒータ制御ルーチンのフローチャート
【図６】 第１実施形態での目標温度設定ルーチンのフローチャート
【図７】 第２実施形態での目標温度設定ルーチンのフローチャート
【図８】 センサ素子の被毒と反転周期との関係を示す図
【符号の説明】
１ エンジン
３ 燃料噴射弁
４ コントロールユニット
７ 排気通路
８ 空燃比センサ
１１ センサ素子
１２ ヒータ
１３ スイッチング素子
１４ スイッチング素子
１５ ＣＰＵ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heater control device for an air-fuel ratio sensor (including an oxygen sensor) equipped with a heater for heating a sensor element that is mounted on an exhaust system of an internal combustion engine and used for air-fuel ratio control.
[0002]
[Prior art]
As an air-fuel ratio control device for an internal combustion engine, an air-fuel ratio sensor detects an actual air-fuel ratio based on oxygen concentration in exhaust gas, etc., and feedback-controls the amount of fuel supplied to the engine so that this becomes a target air-fuel ratio It has been known.
[0003]
By the way, in order to perform the above air-fuel ratio feedback control, it is a precondition that the air-fuel ratio sensor is activated, and the air-fuel ratio sensor is activated when its element temperature reaches a predetermined activation temperature. The air-fuel ratio sensor is equipped with a heater for heating the sensor element, and the element temperature is controlled to the target temperature by controlling energization to the heater (for example, Japanese Patent Laid-Open Nos. 7-198679 and 8-278279). See the official gazette).
[0004]
Specifically, the internal resistance of the sensor element is measured, and the energization amount to the heater is feedback-controlled based on the element temperature estimated from this, so that this becomes the target temperature.
[0005]
[Problems to be solved by the invention]
By the way, for the purpose of reducing the power consumption in the heater, it is better to keep the target temperature of the element temperature of the air-fuel ratio sensor low near the lower limit (for example, 350 ° C.) of the active temperature range.
[0006]
However, when the element temperature of the air-fuel ratio sensor is lowered, the element is poisoned in a short time, and the inversion period of the sensor output becomes longer due to the poisoning, and the air-fuel ratio control performance is degraded.
[0007]
That is, as shown in FIG. 8 , in the poisoned state of the sensor element, the response of the rich to lean element decreases, and as a result, the air-fuel ratio control system output shifts to the rich side, and the exhaust performance and fuel consumption performance are improved. It will fall.
[0008]
In view of such a conventional problem, an object of the present invention is to reduce power consumption of a heater as much as possible while eliminating poisoning of a sensor element.
[0009]
[Means for Solving the Problems]
For this reason, in the invention according to claim 1, as shown in FIG. 1, the element temperature of the air-fuel ratio sensor is measured, and the energization amount to the heater provided in the air-fuel ratio sensor is controlled so as to reach the target temperature. A heater control device for an air-fuel ratio sensor has a means for measuring the number of inversions of the air-fuel ratio sensor output, and the target temperature is switched alternately between the low-temperature side target temperature and the high-temperature side target temperature according to the measured number of inversions. A temperature switching means is provided.
[0010]
Here, the low temperature side target temperature is a temperature near the lower limit in the active temperature range of the sensor element and is a temperature at which the sensor element may be poisoned. The high temperature side target temperature is a temperature at which the sensor element can recover from poisoning.
[0011]
More specifically, as in the invention according to claim 2 , the target temperature switching means sets the target temperature to the low temperature side target temperature until the number of inversions of the air-fuel ratio sensor output reaches the first predetermined value. After that, the target temperature is set to the high temperature side target temperature until the number of inversions of the air-fuel ratio sensor output reaches the second predetermined value.
[0012]
Further, in the invention according to claim 3, as shown in FIG. 1, the element temperature of the air-fuel ratio sensor is measured, and the energization amount to the heater provided in the air-fuel ratio sensor is controlled so as to reach the target temperature. A heater control device for an air-fuel ratio sensor has means for measuring an inversion period of an air-fuel ratio sensor output, and the target temperature is increased from a low-temperature side target temperature when the measured inversion period becomes equal to or greater than a first predetermined value. The target temperature is changed from the high-temperature-side target temperature to the low-temperature-side target temperature when the measured inversion period becomes equal to or less than the second predetermined value that is set smaller than the first predetermined value. A target temperature switching means for switching the target temperature alternately between the low temperature side target temperature and the high temperature side target temperature by switching is provided.
[0013]
In the invention according to claim 4 , as the element temperature measuring means of the air-fuel ratio sensor, the element temperature measuring voltage applying means for temporarily applying a predetermined voltage for element temperature measurement to the sensor element of the air-fuel ratio sensor; An internal resistance calculating unit that calculates the internal resistance of the sensor element based on the sensor output being applied, and an element temperature calculating unit that calculates the element temperature based on the calculated internal resistance are provided.
[0014]
【The invention's effect】
According to the first to fourth aspects of the invention, when the element temperature of the air-fuel ratio sensor is controlled by controlling the amount of current supplied to the heater, the target temperature is alternately switched between the low temperature side target temperature and the high temperature side target temperature. While trying to reduce heater power consumption at the target temperature, even if poisoned at this time, it can be recovered from poisoning at the target temperature on the high temperature side, eliminating poisoning of the sensor element as much as possible Heater power consumption can be reduced.
[0015]
In particular , according to the first and second aspects of the invention, by utilizing the fact that the inversion period of the air-fuel ratio sensor output is substantially constant, the number of inversions of the sensor output is measured, and the target temperature is set according to the measured number of inversions. More specifically, by switching between the low temperature side target temperature and the high temperature side target temperature, the number of inversions of the sensor output reaches the first predetermined value with the target temperature set to the low temperature side target temperature. The target temperature is switched to the high temperature side target temperature, and when the number of inversions of the sensor output reaches the second predetermined value in this state, the target temperature is set to the low temperature side target. By returning to the temperature, simple control can be realized.
[0016]
Particularly , according to the invention of claim 3 , since the inversion period of the air-fuel ratio sensor output becomes longer due to poisoning, the inversion period of the sensor output is measured, and based on this , the target temperature is set as the low temperature side target temperature. By switching to the high temperature side target temperature, that is, when it is determined that there is poisoning, by setting the target temperature to the high temperature side target temperature, the influence of poisoning can be monitored directly and the use of the internal combustion engine When there is variation in the time required for sensor element poisoning due to the environment, fuel properties, etc., optimal control can achieve both a reduction in heater power consumption and improved control performance by eliminating poisoning at a high level.
[0017]
In particular , according to the fourth aspect of the present invention, when measuring the element temperature, a predetermined voltage for measuring the element temperature is temporarily applied to the sensor element of the air-fuel ratio sensor, and the inside of the sensor element is determined based on the sensor output at this time. By calculating the resistance and calculating the element temperature based on the internal resistance, the element temperature can be accurately measured (estimated).
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 2 is a system diagram of an air-fuel ratio feedback control apparatus for an internal combustion engine.
[0019]
An internal combustion engine (hereinafter referred to as an engine) 1 is provided with a fuel injection valve 3 so as to face the intake passage 2 or the combustion chamber for each cylinder, and the fuel injection of each fuel injection valve 3 is controlled by a control unit 4. The
[0020]
For example, the control unit 4 calculates the stoichiometric (λ = 1) from the intake air amount Qa detected based on the signal from the air flow meter 5 and the engine speed Ne detected based on the signal from the crank angle sensor 6. ) An equivalent basic fuel injection amount Tp = K × Qa / Ne (K is a constant) is calculated, and this is calculated based on the air / fuel ratio feedback based on the signal from the air / fuel ratio sensor 8 disposed in the exhaust passage 7 in addition to the target air / fuel ratio tλ. Corrected by the correction coefficient α, the final fuel injection amount Ti = Tp × (1 / tλ) × α is calculated, and the fuel injection pulse having a pulse width corresponding to this Ti is synchronized with the engine rotation. Output to the fuel injection valve 3.
[0021]
Here, the air-fuel ratio sensor 8 is disposed in the exhaust passage 7 and outputs a signal corresponding to the oxygen concentration in the exhaust gas. The control unit 4 is based on the signal from the air-fuel ratio sensor 8 and the engine 1. The air-fuel ratio λ of the air-fuel mixture supplied to the engine is detected, and the air-fuel ratio λ is set to increase or decrease by proportional integral control or the like so that the air-fuel ratio λ becomes the target air-fuel ratio tλ. Feedback control is performed at tλ.
[0022]
The air-fuel ratio sensor 8 is a so-called wide-area air-fuel ratio sensor that can detect the air-fuel ratio linearly by continuously changing the output voltage in accordance with the air-fuel ratio, as shown in FIG. 11 A heater provided with a heater 12 for heating is used.
[0023]
FIG. 3 shows a control circuit for the sensor element 11 of the air-fuel ratio sensor 8 and the heater 12 for heating the sensor element.
The output voltage Vs of the sensor element 11 of the air-fuel ratio sensor 8 changes continuously according to the air-fuel ratio, and the output Vs is input to the control unit 4.
[0024]
In addition, a predetermined voltage Vcc (for example, 5 V) for element temperature measurement (for internal resistance measurement) is applied to the sensor element 11 via the switching element 13 and the reference resistor R0. Therefore, when the switching element 13 is turned on during element temperature measurement, a voltage component for element temperature measurement is superimposed on the output Vs of the sensor element 11.
[0025]
A battery voltage VB is applied to the heater 12, and a switching element 14 is provided in the energization circuit.
The CPU 15 in the control unit 4 controls the ON / OFF of the switching element 13 for applying the element temperature measurement voltage, and filters the output Vs of the sensor element 11 with a filter (smoothing circuit) 16 and A / Reading is performed via the D converter 17.
[0026]
Further, the CPU 15 controls the energization amount to the heater 12 by duty-controlling ON / OFF of the heater control switching element 14 via the D / A converter 18.
[0027]
Next, the control content of the CPU 15 will be described with reference to a flowchart.
FIG. 4 is a flowchart of the element temperature measurement routine, which is executed at a predetermined crank angle cycle. This routine corresponds to element temperature measuring means.
[0028]
In step 1 (denoted as S1 in the figure, the same applies hereinafter), the sensor output Vs is read in order to detect the air-fuel ratio, and Vaf = Vs, and the air-fuel ratio λ is detected based on this.
In step 2, the switching element 13 is turned ON and application of the element temperature measurement voltage Vcc to the sensor element 11 is started. That is, application of the element temperature measurement voltage Vcc is started immediately after reading the sensor output for air-fuel ratio detection. This portion corresponds to the element temperature measurement voltage applying means.
[0029]
In step 3, after a predetermined time from the start of application of the element temperature measurement voltage, the sensor output Vs is read and Vr = Vs to measure the internal resistance of the sensor element 11.
In step 4, the sensor output Vr during voltage application is corrected by the sensor output Vaf immediately before voltage application. Specifically, the corrected sensor output Vr = Vr−Vaf is obtained by subtracting the sensor output Vaf immediately before voltage application from the sensor output Vr during voltage application.
[0030]
In step 5, the internal resistance Rs of the sensor element 11 is calculated based on the corrected sensor output Vr. This part corresponds to the internal resistance calculating means.
Specifically, if the current flowing through the sensor element 11 is i and Vs = Vr,
Vr = i × Rs
Vcc−Vr = i × R0
So, from both formulas,
Rs = Vr / [(Vcc−Vr) / R0]
As a result, the internal resistance Rs is calculated.
[0031]
In step 6, the element temperature Ts is calculated from the internal resistance Rs of the sensor element 11 by referring to a table. This is because as the element temperature Ts increases, the internal resistance Rs decreases, so that the element temperature Ts can be calculated from the internal resistance Rs. This portion corresponds to element temperature calculation means.
[0032]
In step 7, the switching element 13 is turned OFF after a predetermined time from the start of application of the element temperature measurement voltage, thereby stopping (ending) application of the element temperature measurement voltage Vcc to the sensor element 11.
[0033]
FIG. 5 is a flowchart of the heater control routine, which is executed every predetermined time during normal operation. This routine corresponds to heater energization amount control means.
In step 11, the latest element temperature Ts calculated by the routine of FIG. 4 is read.
[0034]
In step 12, a target temperature (low temperature side target temperature TL or high temperature side target temperature TH) set by a routine of FIG. 6 or FIG. 7 described later is read.
In step 13, the heater duty HDUTY (%) is calculated so as to bring the element temperature Ts closer to the target temperature by well-known PID control according to the deviation between the actual element temperature Ts and the target temperature.
[0035]
Specifically, when the actual element temperature Ts is lower than the target temperature, the heater duty HDUTY is increased so as to increase the energization amount (energization time ratio) to the heater 12, and conversely, the actual element temperature Ts. Is higher than the target temperature, the heater duty HDUTY is decreased so as to decrease the energization amount (energization time ratio) to the heater 12.
[0036]
In step 14, the calculated heater duty HDUTY is output, thereby controlling the energization amount to the heater 12 by turning on / off the switching element 14 to converge the element temperature Ts to the target temperature.
[0037]
Here, in the present invention, the target temperature is alternately switched between the low temperature side target temperature TL and the high temperature side target temperature TH in the feedback control of the element temperature of the air-fuel ratio sensor 8 by the energization amount control to the heater 12. In terms of time ratio, basically, the low temperature side target temperature TL is set, and the temperature is temporarily switched to the high temperature side target temperature TH.
[0038]
The low temperature side target temperature TL here is a temperature near the lower limit (for example, 350 ° C.) in the activation temperature range of the air-fuel ratio sensor and is a temperature at which the sensor element may be poisoned. The high temperature side target temperature TH is a temperature at which the sensor element can be poisoned (for example, 750 ° C.).
[0039]
FIG. 6 is a flowchart of a target temperature setting routine in the first embodiment. This routine corresponds to target temperature switching means.
[0040]
In step 31, first, the target temperature is set to the low temperature side target temperature TL (for example, 350 ° C.) .
In step 32, the number of inversions of the sensor output with the target temperature set to the low temperature side target temperature TL is measured (sensor output inversion number measuring means). In step 33, the number of inversions is a first predetermined value. It is determined whether or not A is greater than or equal to A.
[0041]
If it is less than the first predetermined value A, the target temperature is maintained at the low temperature side target temperature TL, the number of inversions is continuously measured, and when the first predetermined value A is reached, the routine proceeds to step 34.
In step 34, the target temperature is switched to a high temperature side target temperature TH (for example, 750 ° C.) at which the sensor element can recover from poisoning.
[0042]
In step 35, the number of inversions of the sensor output with the target temperature set to the high temperature side target temperature TH is measured (sensor output inversion number measuring means), and in step 36, the number of inversions is a second predetermined value. It is determined whether or not B or more. B <A.
[0043]
If it is less than the second predetermined value B, the target temperature is maintained at the high temperature side target temperature TH, and the measurement of the number of inversions is continued. When the second predetermined value B is reached, the process returns to step 31 and the target again The temperature is switched to the low temperature side target temperature TL.
[0044]
In this way, in feedback control of the element temperature of the air-fuel ratio sensor 8 by controlling the amount of current supplied to the heater 12, the target temperature is alternately switched according to the time schedule (number of sensor output inversions), and the target temperature is set as low as possible on the low temperature side target. The temperature TL is set to reduce power consumption in the heater 12, while the low temperature side target temperature TL may be poisoned. Therefore, the number of inversions of the sensor output at the low temperature side target temperature TL is the first predetermined number. When the value A is reached, the target temperature is temporarily switched to the high temperature side target temperature TH (until the number of inversions of the sensor output reaches the second predetermined value B) to recover from poisoning. It is.
[0045]
That is, the first embodiment uses the fact that the sensor output inversion period of the air-fuel ratio sensor is substantially constant, and defines the time schedule based on the count value of the number of sensor output inversions. . The first predetermined value A generally corresponds to the time order, while the second predetermined value B generally corresponds to the minute order (B <A).
[0046]
Accordingly, it is possible to avoid the influence due to poisoning of the sensor element while minimizing the power consumption in the heater 12.
[0047]
The mechanism of poisoning and detoxification of the air-fuel ratio sensor is as follows.
(1) Mechanism of poisoning SiO2, active Si, active P, active Zr, etc. contained in the atmosphere and oil adhere to the surface of the sensor element (the surface of the protective layer covering the Pt electrode on zirconia) through exhaust gas. To do. After that, entering the protective layer and clogging the protective layer, gas permeability is lowered, or even reaches the Pt electrode and adheres, thereby inhibiting the movement of O2 ions on the surface of the Pt electrode. To do.
[0048]
(2) Mechanism of detoxification When the element temperature is increased to 750 ° C. or higher, the activation energy such as active Si and active P adhering to the element increases, so that these adhering to the protective layer and the Pt electrode can be prevented. Disappear and fly away.
[0049]
Next, another embodiment of the present invention will be described.
FIG. 7 is a flowchart of a target temperature setting routine in the second embodiment , which is executed instead of the flow of FIG. This routine corresponds to target temperature switching means.
In step 41, first, the target temperature is set to the low temperature side target temperature TL.
[0050]
In step 42, the inversion cycle of the sensor output is measured in a state where the target temperature is set to the low temperature side target temperature TL. In step 43, it is determined whether or not the inversion cycle is equal to or greater than the first predetermined value A. judge.
[0051]
If it is less than the first predetermined value A, the target temperature is maintained at the low temperature side target temperature TL, and the measurement of the inversion period is continued. Proceed to step 44.
[0052]
In step 44, the target temperature is switched to a high temperature side target temperature TH at which the sensor element can recover from poisoning.
In step 45, the sensor output reversal cycle is measured with the target temperature set to the high temperature side target temperature TH. In step 46, it is determined whether the reversal cycle is equal to or less than a second predetermined value B. judge. The second predetermined value B is obtained by adding hysteresis to the first predetermined value A, and is set smaller than the first predetermined value A by the amount of hysteresis.
[0053]
If the second predetermined value B is exceeded, the target temperature is maintained at the high temperature side target temperature TH, and the reversal period is continuously measured. Then, returning to step 41, the target temperature is switched again to the low temperature side target temperature TL.
[0054]
Here, the steps 42 and 45 correspond to the sensor output reversal period measuring means, and the steps 43 and 46 correspond to the poisoning determination means.
In the second embodiment , when the air-fuel ratio sensor is poisoned, the response of the rich-to-lean element decreases as shown in FIG. 8 , and the inversion period TRV of the sensor output becomes longer. Therefore, the inversion period is measured. If it is less than the predetermined value, it is determined that there is no poisoning, and the heater power consumption is reduced by setting the target temperature TL to the low temperature side. Thus, recovery from poisoning can be achieved by switching to the high temperature side target temperature TH.
[0055]
When the target temperature of the element temperature is set by the time schedule setting, the low temperature setting time is shortened and the high temperature setting time is lengthened in consideration of variations in the time to element poisoning due to the engine operating environment and gasoline properties, etc. However, in the second embodiment , since the influence of element poisoning is directly monitored, the above-described margin is unnecessary, so that it is possible to further reduce the heater power consumption.
[0056]
As the inversion cycle for the poisoning determination, in addition to the inversion cycle TRV in FIG. 8 , a rich to lean inversion cycle TRL may be measured.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing the configuration of the present invention. FIG. 2 is a system diagram of an air / fuel ratio feedback control device for an engine showing an embodiment of the present invention. FIG. 3 is a control circuit diagram for sensor elements and heaters of an air / fuel ratio sensor. FIG. 4 is a flowchart of an element temperature measurement routine. FIG. 5 is a flowchart of a heater control routine. FIG. 6 is a flowchart of a target temperature setting routine in the first embodiment. FIG. 7 is a flowchart of a target temperature setting routine in the second embodiment. Flowchart [Fig. 8] Diagram showing relationship between sensor element poisoning and inversion cycle
1 engine
3 Fuel injection valve
4 Control unit
7 Exhaust passage
8 Air-fuel ratio sensor
11 Sensor element
12 Heater
13 Switching element
14 Switching elements
15 CPU

Claims (4)

空燃比センサの素子温度を計測して、目標温度となるように、空燃比センサに備えられるヒータへの通電量を制御する空燃比センサのヒータ制御装置において、
空燃比センサ出力の反転回数を計測する手段を有し、計測された反転回数に従って、前記目標温度を低温側目標温度と高温側目標温度とに交互に切換える目標温度切換手段を設けたことを特徴とする空燃比センサのヒータ制御装置。In the heater control device for an air-fuel ratio sensor that measures the element temperature of the air-fuel ratio sensor and controls the energization amount to the heater provided in the air-fuel ratio sensor so as to reach the target temperature,
It has means for measuring the number of inversions of the air-fuel ratio sensor output, and provided with target temperature switching means for alternately switching the target temperature between the low temperature side target temperature and the high temperature side target temperature according to the measured number of inversions. A heater control device for an air-fuel ratio sensor. 前記目標温度切換手段は、空燃比センサ出力の反転回数が第１の所定値に達するまでの間、目標温度を低温側目標温度に設定し、この後、空燃比センサ出力の反転回数が第２の所定値に達するまでの間、目標温度を高温側目標温度に設定することを特徴とする請求項１記載の空燃比センサのヒータ制御装置。The target temperature switching means sets the target temperature to the low temperature side target temperature until the number of inversions of the air-fuel ratio sensor output reaches the first predetermined value. The heater control device for an air-fuel ratio sensor according to claim 1, wherein the target temperature is set to the high temperature side target temperature until the predetermined value is reached. 空燃比センサの素子温度を計測して、目標温度となるように、空燃比センサに備えられるヒータへの通電量を制御する空燃比センサのヒータ制御装置において、
空燃比センサ出力の反転周期を計測する手段を有し、計測された反転周期が第１の所定値以上となった時点で前記目標温度を低温側目標温度から高温側目標温度に切換え、その後、計測された反転周期が前記第１の所定値より小さく設定された第２の所定値以下となった時点で前記目標温度を高温側目標温度から低温側目標温度に切換えることによって、前記目標温度を低温側目標温度と高温側目標温度とに交互に切換える目標温度切換手段を設けたことを特徴とする空燃比センサのヒータ制御装置。In the heater control device for an air-fuel ratio sensor that measures the element temperature of the air-fuel ratio sensor and controls the energization amount to the heater provided in the air-fuel ratio sensor so as to reach the target temperature,
Means for measuring an inversion period of the air-fuel ratio sensor output, and when the measured inversion period becomes equal to or greater than a first predetermined value, the target temperature is switched from the low temperature side target temperature to the high temperature side target temperature; The target temperature is changed by switching the target temperature from the high temperature side target temperature to the low temperature side target temperature when the measured inversion period becomes equal to or less than the second predetermined value set smaller than the first predetermined value. A heater control apparatus for an air-fuel ratio sensor, characterized in that target temperature switching means for alternately switching between a low temperature side target temperature and a high temperature side target temperature is provided. 空燃比センサの素子温度計測手段として、空燃比センサのセンサ素子に素子温度計測用の所定の電圧を一時的に印加する素子温度計測用電圧印加手段と、前記電圧印加中のセンサ出力に基づいてセンサ素子の内部抵抗を算出する内部抵抗算出手段と、算出された内部抵抗に基づいて素子温度を算出する素子温度算出手段とを備えることを特徴とする請求項１〜請求項３のいずれか１つに記載の空燃比センサのヒータ制御装置。As element temperature measuring means of the air-fuel ratio sensor, element temperature measuring voltage applying means for temporarily applying a predetermined voltage for element temperature measurement to the sensor element of the air-fuel ratio sensor, and based on the sensor output during the voltage application and the internal resistance calculation means for calculating the internal resistance of the sensor element, any one of claims 1 to 3, characterized in that it comprises a device temperature calculating means for calculating the element temperature based on the internal resistance calculated 1 A heater control device for an air-fuel ratio sensor according to claim 1.
JP2000147165A 2000-05-19 2000-05-19 Heater control device for air-fuel ratio sensor Expired - Fee Related JP3764842B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2000147165A JP3764842B2 (en) 2000-05-19 2000-05-19 Heater control device for air-fuel ratio sensor
DE2001124134 DE10124134A1 (en) 2000-05-19 2001-05-17 Heater control device and heater control method of an air / fuel ratio sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2000147165A JP3764842B2 (en) 2000-05-19 2000-05-19 Heater control device for air-fuel ratio sensor

Publications (2)

Publication Number Publication Date
JP2001330583A JP2001330583A (en) 2001-11-30
JP3764842B2 true JP3764842B2 (en) 2006-04-12

Family

ID=18653380

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2000147165A Expired - Fee Related JP3764842B2 (en) 2000-05-19 2000-05-19 Heater control device for air-fuel ratio sensor

Country Status (2)

Country Link
JP (1) JP3764842B2 (en)
DE (1) DE10124134A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10260720A1 (en) * 2002-12-23 2004-07-15 Robert Bosch Gmbh Method for operating a gas sensor and device for carrying out the method
DE102006043089A1 (en) * 2006-09-14 2008-03-27 Robert Bosch Gmbh Gas sensor, in particular lambda probe for motor vehicles with internal combustion engines
JP5559960B2 (en) * 2008-05-28 2014-07-23 トヨタ自動車株式会社 NOx sensor and its degradation suppression recovery control device
JP2011144779A (en) * 2010-01-18 2011-07-28 Toyota Motor Corp Device for determining imbalance between air-fuel ratio cylinders of internal combustion engine
US9146210B2 (en) * 2010-11-02 2015-09-29 Bradley Gibson Control system and method for heating an oxygen sensor
JP2014092135A (en) * 2012-11-06 2014-05-19 Denso Corp Fuel injection control device
JP7247989B2 (en) * 2020-07-31 2023-03-29 株式会社デンソー sensor controller

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57192849A (en) * 1981-05-25 1982-11-27 Toyota Central Res & Dev Lab Inc Detecting device for limit current system oxygen concentration performing temperature compensation of measuring output
JPS62165558U (en) * 1986-04-10 1987-10-21
JP2580053B2 (en) * 1990-01-25 1997-02-12 日産自動車株式会社 Air-fuel ratio control device
JP3603912B2 (en) * 1995-07-21 2004-12-22 本田技研工業株式会社 Oxygen sensor and air-fuel ratio control device for internal combustion engine
JPH1018886A (en) * 1996-07-05 1998-01-20 Mazda Motor Corp O2-sensor degradation detection method and device for the same
JP3669788B2 (en) * 1996-08-30 2005-07-13 大阪瓦斯株式会社 Oxygen concentration measuring device
JP3650266B2 (en) * 1998-05-18 2005-05-18 株式会社日立製作所 Control device for oxygen sensor with heater

Also Published As

Publication number Publication date
DE10124134A1 (en) 2002-02-07
JP2001330583A (en) 2001-11-30

Similar Documents

Publication Publication Date Title
US5970967A (en) Method and apparatus for diagnosing an abnormality in a wide range air-fuel ratio sensor
US7013214B2 (en) Air-fuel ratio feedback control apparatus and method for internal combustion engine
JP3785024B2 (en) Catalyst temperature detector
JPH1182114A (en) Air-fuel ratio control device for internal combustion engine
US6712054B2 (en) Device and method for measuring element temperature of air-fuel ratio sensor, and device and method for controlling heater of air-fuel ratio sensor
JP3764842B2 (en) Heater control device for air-fuel ratio sensor
JP3687495B2 (en) Exhaust gas purification device for internal combustion engine
JPH065047B2 (en) Air-fuel ratio controller
JP3982624B2 (en) Heater control device
JP2600807B2 (en) Control device for internal combustion engine
JP3764841B2 (en) Element temperature measuring device and heater control device for air-fuel ratio sensor
JP2008038720A (en) Abnormality diagnosis device for downstream side oxygen sensor of exhaust emission control system
JP3992004B2 (en) Engine air-fuel ratio control device
JP3869629B2 (en) Air-fuel ratio sensor activity determination device
JPH11166438A (en) Air-fuel ratio sensor deterioration detector for internal combustion engine
JPH07325066A (en) Control device for heating means for air-fuel ratio sensor
JP2005337213A (en) Diagnosis device for air fuel ratio sensor
JP3734685B2 (en) Sensor element temperature detection device for air-fuel ratio sensor
JP2004108187A (en) Deterioration diagnosis device of exhaust emission control catalyst for internal combustion engine
JP3854040B2 (en) Air-fuel ratio detection device for internal combustion engine
JPS6312855A (en) Air-fuel ratio controller for internal combustion engine
JP3608443B2 (en) Air-fuel ratio control device for internal combustion engine
JPH0531739B2 (en)
JP2001323838A (en) Element temperature measuring device for air-fuel ratio sensor and heater control device
JPH08284651A (en) Catalyst temperature estimating device for internal combustion engine

Legal Events

Date Code Title Description
A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20041129

A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20041217

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20050329

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20050527

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20060110

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20060123

R150 Certificate of patent or registration of utility model

Free format text: JAPANESE INTERMEDIATE CODE: R150

LAPS Cancellation because of no payment of annual fees