JP4117472B2 - EGR device - Google Patents

EGR device Download PDF

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JP4117472B2
JP4117472B2 JP2003066688A JP2003066688A JP4117472B2 JP 4117472 B2 JP4117472 B2 JP 4117472B2 JP 2003066688 A JP2003066688 A JP 2003066688A JP 2003066688 A JP2003066688 A JP 2003066688A JP 4117472 B2 JP4117472 B2 JP 4117472B2
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valve
opening
egr valve
egr
engine
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JP2004278307A (en
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英司 高山
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Denso Corp
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Denso Corp
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    • 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
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0047—Controlling exhaust gas recirculation [EGR]
    • F02D41/005—Controlling exhaust gas recirculation [EGR] according to engine operating conditions
    • F02D41/0055—Special engine operating conditions, e.g. for regeneration of exhaust gas treatment apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/45—Sensors specially adapted for EGR systems
    • F02M26/48—EGR valve position sensors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/49—Detecting, diagnosing or indicating an abnormal function of the EGR system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/52—Systems for actuating EGR valves
    • F02M26/53—Systems for actuating EGR valves using electric actuators, e.g. solenoids
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、エンジンの排気ガスの一部を吸気側へ戻すＥＧＲ（排気ガス再循環）装置に関するものである。
【０００２】
【従来の技術】
近年、排気規制が厳しくなっていく現状下においてＥＧＲ装置が重要となっており、エンジンの運転状態に応じてバルブ開度小〜バルブ開度大までのＥＧＲバルブの開度制御が必要となっている。
例えば、ディーゼルエンジンでは、アイドリング時の排気ガスを低減する目的で排気ガスを吸気側に戻すが、アイドリング状態では吸気負圧が小さく、且つ排気圧も低いため、必要量の排気ガスを吸気側へ戻すためにＥＧＲバルブのバルブ開度を大きくしている。この時、油分を含んだパティキュレートがＥＧＲバルブのバルブシート等に付着し、付着したパティキュレートによってＥＧＲバルブが開弁しない場合（閉弁固着）がある。
【０００３】
ここで、ＥＧＲバルブの開度を可変するＥＧＲ装置では、ＥＧＲバルブの実開度をバルブリフト量や吸入空気量等から読取り、この実開度が目標開度になるようにフィードバック制御をしている。
このため、従来では、バルブシート等に付着したパティキュレートによってＥＧＲバルブが閉弁固着した場合、ＥＧＲバルブの開弁指令値が徐々に大きくなっていく。そして、開弁に必要な駆動力に達するとＥＧＲバルブが開弁する。
このため、ＥＧＲバルブに開弁指示が与えられてから実際に開弁するまでの開弁遅れが発生してしまう。つまり、閉弁固着が発生してしまうと、適切なＥＧＲ量が得られない時間が長くなってしまう不具合がある。
【０００４】
また、上記作動による固着解消後の開弁は、実開度が本来目標とする開度より大きくなってしまうため、次にフィードバック制御によって実開度を小さくする動作を行う。つまり、従来では、固着解消のためにオーバーシュートした実開度をフィードバック制御で本来目標とする開度に近づけるため、固着解消後に目標開度に達するのにも時間がかかってしまう。
【０００５】
ＥＧＲバルブの閉弁固着を回避する技術として、イグニッションスイッチをON（あるいはスタータスイッチをON）してから、ＥＧＲバルブの通常開度制御が開始される前までの期間に、ＥＧＲバルブのアクチュエータ（リニアソレノイド等）を強制通電させて閉弁固着を解消する技術が知られている（例えば、特許文献１参照）。
【０００６】
【特許文献１】
特開平７−２９３３５５号公報
【０００７】
【発明が解決しようとする課題】
上記特許文献１に開示される技術は、エンジンの始動のためにイグニッションスイッチをON（あるいはスタータスイッチをON）してから、所定の時間、あるいはセンサによって固着解除が検出されるまでの間、ＥＧＲバルブを強制開弁する技術である。
このため、クランキング中においてＥＧＲバルブが強制開弁され、クランキング中に燃焼室に吸い込まれる混合気の未燃焼ガスの割合が増え、逆に空気の割合が減る。このような空燃比の悪化により、始動時の着火性が下がるため、始動開始（イグニッションスイッチの操作）からエンジンが完爆するまでの始動時間が長くなるとともに、始動時に大量のスモークが発生してしまう。
【０００８】
また、エンジンの始動性能の悪化を回避するために、ＥＧＲバルブを強制開弁する期間を、イグニッションスイッチONからクランキング開始（エンジン回転開始）までにすることも考えられるが、ＥＧＲバルブを強制開弁する時間が極めて短くなる。すると、ＥＧＲバルブが固着していても、強制開弁の実行時間が極めて短くなるため、固着解除できない可能性が高まる。
【０００９】
ここで、上記特許文献１に開示される技術には、エンジンの始動時にＥＧＲバルブの固着解除が検出されない場合、エンジンの始動完了後であっても通常開度制御の開始を延期して、再度強制通電させて強制開弁を図る技術が開示されている。
しかし、この技術であっても、再度強制通電を実施する前のクランキング中にもＥＧＲバルブが強制開弁されていることに変わりがなく、クランキング中の空燃比の悪化により、始動時間が長くなるとともに、始動時に大量のスモークが発生する。
【００１０】
【発明の目的】
本発明は、上記の事情に鑑みてなされたものであり、その目的は、エンジンの始動性能の悪化を招くことなく、ＥＧＲバルブの固着を解除できるＥＧＲ装置の提供にある。
【００１１】
【課題を解決するための手段】
〔請求項１の手段〕
請求項１の発明では、固着検出手段がエンジンの始動完了後のエンジン運転中にＥＧＲバルブの閉弁固着を検出するように設けられており、この固着検出手段がＥＧＲバルブの閉弁固着を検出すると、エンジンの始動完了後のエンジン運転中にアクチュエータへ開弁に必要な駆動力を与えて強制開弁する。このため、ＥＧＲバルブが閉弁固着した場合に、ＥＧＲバルブを素早く開弁できる。
このように、ＥＧＲバルブに閉弁固着が発生しても、素早く閉弁固着が解除されるため、素早く適切なＥＧＲ量を得ることができる。
【００１２】
また、特許文献１で示した始動時（エンジンの完爆前）にＥＧＲバルブを強制開弁する技術では、クランキング中の空燃比の悪化により、エンジンの始動時間が長くなるとともに、大量のスモークが発生する不具合が生じる。
これに対し、請求項１の発明は、エンジンの始動完了後のエンジン運転中にＥＧＲバルブの閉弁固着を認識した時にＥＧＲバルブを強制開弁する技術であるため、クランキング中に空燃比が悪化する不具合がない。このため、始動時間が延長する不具合がなく、また始動時に大量のスモークが発生する不具合も回避できる。
さらに、固着検出手段がＥＧＲバルブの閉弁固着を検出しても、エンジンの回転数が所定回転以上で、且つエンジンにかかる負荷が所定負荷以上の時には、強制開弁の動作を実行しないように設ける。
このように設けることにより、エンジンのトルクが大きい時にＥＧＲ量が急激に変わってトルクが急激に変化する不具合がない。
【００１３】
〔請求項２の手段〕
請求項２の手段を採用し、ＥＧＲバルブの目標開度と実開度の差が一定値以上で、且つＥＧＲバルブの目標開度が所定値以上の時に、ＥＧＲバルブの閉弁固着を検出するように設けても良い。
【００１４】
〔請求項３の手段〕
請求項３の手段を採用し、ＥＧＲバルブの目標開度と実開度の差が一定値以上で、且つＥＧＲバルブの目標開度が所定値以上の状態が所定時間以上続く時に、ＥＧＲバルブの閉弁固着を検出するように設けても良い。
【００１８】
【発明の実施の形態】
本発明の実施の形態を、実施例および変形例を用いて説明する。
［実施例］
図１を参照してディーゼルエンジン等に搭載されるＥＧＲ装置を説明する。
ＥＧＲ装置は、エンジン１の吸気管２と排気管３とを連通するＥＧＲ配管４に設けられたＥＧＲバルブ５と、このＥＧＲバルブ５の開度を調整するＥＣＵ６（エンジン・コントロール・ユニットの略であり、制御装置に相当する）とを備える。
【００１９】
ＥＧＲバルブ５は、図２の断面図に示されるように、吸気管２に連通する管内４ａと、排気管３に連通する管内４ｂとを区画する仕切壁７に設けられた２つのバルブシート８を、２つの弁体９で開閉するものであり、２つの弁体９はリニアソレノイド１０（アクチュエータの一例）によって駆動される。このリニアソレノイド１０は、ＥＣＵ６によってデューティ比制御されて、２つの弁体９の開度（ＥＧＲ配管４の連通度合に相当する）を０％〜１００％の範囲で調整するものである。
【００２０】
ＥＣＵ６は、車両の運転状態等に応じてエンジン１の制御（ＥＧＲバルブ５の制御を含む）を行うものであり、運転状態を検出するために種々のセンサ類からの出力を受ける。
ＥＣＵ６に出力されるセンサ類の一例としては、図１に示されるように、吸気管２を流れる吸入空気量を検出するエアフローセンサ１１、乗員が操作するアクセル開度を検出するスロットポジションセンサ１２、エンジン回転速度を検出するエンジンスピードセンサ１３、エンジン１の冷却水温度を検出するウォータテンプセンサ１４、ＥＧＲバルブ５の開度を直接検出するリフトセンサ１５等がある。
【００２１】
ＥＣＵ６は、上記センサ類によって検出された車両の運転状態に基づいてＥＧＲバルブ５の目標リフト（目標開度に相当する）をマップや計算式等から演算し、演算によって求めた目標リフトが、リフトセンサ１５で検出される実リフト（実開度に相当する）と一致するようにフィードバック制御するように設けられている。
【００２２】
ここで、ＥＧＲバルブ５によって吸気管２に戻される排気ガスは、図２に示すバルブシート８内を通過するものであるため、排気ガス中に含まれるパティキュレートがバルブシート８や弁体９に付着する。特に、アイドル状態などの低負荷では、大きなＥＧＲ量を要求され、かつ排気ガス温度も低くなっていることにより、排気ガス中のパティキュレートは油分を多く含んでいる。
このため、バルブシート８や弁体９に付着した油分を含むパティキュレートによって弁体９が閉弁固着する可能性がある。
【００２３】
そこで、ＥＣＵ６は、エンジン１の始動完了後（スタータスイッチのOFF 時であり、クランキングの停止時）のエンジン運転中（エンジン１の回転速度がクランキングによる回転速度より速い状態）にＥＧＲバルブ５の閉弁固着を検出する固着検出手段（固着検出のためのプログラム）を備える。
そして、ＥＣＵ６は、この固着検出手段がＥＧＲバルブ５の閉弁固着を検出すると、エンジン運転中における通常のフィードバック制御を一時中止して、リニアソレノイド１０へ開弁に必要な駆動力（この実施例ではデューティ比１００％）を与えて強制開弁し、リフトセンサ１５によって開弁が確認された時には通常のフィードバック制御に復帰するように設けられている。
【００２４】
この実施例における固着検出手段は、▲１▼ＥＣＵ６が算出するＥＧＲバルブ５の目標リフトとリフトセンサ１５が検出する実リフトの差が一定値以上（目標リフト−実リフト≧一定値）であり、▲２▼ＥＣＵ６が算出するＥＧＲバルブ５の目標リフトが所定値以上（目標リフト≧所定値）であり、▲３▼上記▲１▼、▲２▼の状態が所定時間以上続く時（▲１▼、▲２▼の継続時間≧所定時間）に、ＥＧＲバルブ５の閉弁固着を検出するものである。
【００２５】
また、ＥＣＵ６は、上述した強制開弁を実施した後（リニアソレノイド１０に全開指令であるデューティ比１００％を出力した後）、▲４▼リフトセンサ１５の検出する実リフトが所定リフトに達した時（実リフト≧所定リフト）に強制開弁を停止して、通常のフィードバック制御に復帰するものである。
しかし、ＥＣＵ６は、固着検出手段がＥＧＲバルブ５の閉弁固着を検出した時であっても、▲５▼エンジン１の回転数が所定回転以上であり、▲６▼エンジン１にかかる負荷が所定負荷以上（例えば、燃料噴射量が所定噴射量以上の時）には強制開弁の動作を実行しないように設けられている。これによって、エンジン１のトルクが大きい時にＥＧＲ量が急激に変化してドライバビリティが悪化する不具合を防いでいる。
【００２６】
一方、ＥＣＵ６には、ＥＧＲバルブ５の閉弁固着を検出して強制開弁を開始してから所定時間に亘ってＥＧＲバルブ５の開弁が認められない時に強制開弁を停止してＥＧＲバルブ５の異常信号を発生するプログラムが成されている。
このＥＧＲバルブ５の異常信号が発生すると、ＥＣＵ６内にプログラムされたＥＧＲバルブ５の診断ロジックが作動してＥＧＲバルブ５の異常が発生した旨が認識され、乗員等に警告ランプ等で警告するように設けられてる。
【００２７】
次に、上記ＥＣＵ６の制御を図３のフローチャートに基づいて説明する。
この制御フローでは、まずエンジン１の始動完了後のエンジン運転中であるか否かの判断を行う（ステップＳ1 ）。具体的な一例を示すと、キースイッチのイグニッションスイッチ（ＩＧスイッチ）がONの状態で、且つエンジン１の回転速度が所定の回転速度（クランキング時の回転速度）よりも速い状態であるか否かの判断を行う。この判断結果がNOの場合はリターンする。
【００２８】
ステップＳ1 の判断結果がYES の場合は、ＥＧＲバルブ５の制御実行中であるか否かを判断する（ステップＳ2 ）。この判断結果がNOの場合はリターンする。ステップＳ2 の判断結果がYES の場合は、バルブ固着のフラグが立てられていないか否かの判断を行う（ステップＳ3 ）。
このステップＳ3 の判断結果がYES の場合は上述した▲１▼、▲２▼が成立しているか否かを判断する（ステップＳ4 ）。このステップＳ4 の判断結果がNOの場合はＥＧＲバルブ５が正常動作していることを検出し（ステップＳ5 ）、その後リターンする。
【００２９】
ステップＳ4 の判断結果がYES の場合は上述した▲１▼、▲２▼の状態が一定時間継続しているか否かの判断を行う（ステップＳ6 ）。このステップＳ6 の判断結果がNOの場合はリターンする。また、ステップＳ6 の判断結果がYES の場合はバルブ固着のフラグを立て（ステップＳ7 ）、その後リターンする。
ステップＳ3 の判断結果がNOの場合、つまりステップＳ7 でフラグが立てられている場合は、上述した▲４▼が成立しているか否かの判断を行う（ステップＳ8 ）。このステップＳ8 の判断結果がYES の場合はバルブ固着が解消されたと判断してステップＳ5 へ進む。
【００３０】
ステップＳ8 の判断結果がNOの場合は、上述した▲５▼、▲６▼が成立しているか否かを判断する（ステップＳ9 ）。このステップＳ9 の判断結果がYES の場合はＥＧＲバルブ５に１００％のマックスデューティを出力し（ステップＳ10）、その後リターンする。
ステップＳ9 の判断結果がNOの場合は、エンジン１のトルクが大きい時にＥＧＲ量の急激な変化でドライバビリティが悪化する不具合を防ぐために強制開弁の動作を実施せずにそのままリターンする。
【００３１】
次に、エンジン１の始動完了後のエンジン運転中において、ＥＧＲバルブ５に固着が発生した場合におけるＥＧＲバルブ５に与えられるデューティ変化とＥＧＲバルブ５の開度変化とを、図４のグラフを参照して説明する。
エンジン１の運転状態に応じて演算されるＥＣＵ６の目標リフトが破線Ａに示すように上昇すると、その上昇に伴ってＥＧＲバルブ５に与えられるデューティ比が実線Ｂに示すように上昇する。
【００３２】
ＥＧＲバルブ５に固着が発生している場合は、目標リフトが破線Ａに示すように上昇しても、実リフトは実線Ｃに示すように上昇しない。
そして、目標リフトと実リフトの差が一定値以上（図中▲１▼参照）で、且つ目標リフトが所定値以上（図中▲２▼参照）であり、その状態が所定時間以上続く（図中▲３▼参照）と、ＥＣＵ６はＥＧＲバルブ５の閉弁固着を検出する。
すると、ＥＣＵ６は、通常のフィードバック制御を一時中止してＥＧＲバルブ５にデューティ比１００％を出力する。
【００３３】
ＥＧＲバルブ５に全開指示が与えられることで、ＥＧＲバルブ５に大きな開弁の力が発生する。そして、ＥＧＲバルブ５の閉弁固着が解除されると、実リフトが実線Ｃに示すように上昇を開始する。
そして、実リフトが所定リフトに達した時（図中▲４▼参照）に強制開弁を停止して、通常のフィードバック制御に復帰する。
【００３４】
以上の作動に示したように、本実施例のＥＧＲ装置では、エンジン１の始動完了後のエンジン運転中にＥＧＲバルブ５の閉弁固着を検出した場合、ＥＧＲバルブ５に対して開弁に必要な駆動力（デューティ比１００％）を与えて強制開弁するため、エンジン運転中における閉弁固着を短時間で解除できる。このように、ＥＧＲバルブ５に閉弁固着が発生しても、素早く閉弁固着が解除されるため、素早く適切なＥＧＲ量を得ることができる。
【００３５】
また、特許文献１で示した始動時（エンジン１の完爆前）にＥＧＲバルブ５を強制開弁する技術では、クランキング中にＥＧＲバルブ５が強制開弁されるために、クランキング中の空燃比が悪化して、エンジン１の始動時間が長くなるとともに、大量のスモークが発生する不具合が生じる。これに対し、エンジン１の始動完了後のエンジン運転中にＥＧＲバルブ５の閉弁固着を認識した時にＥＧＲバルブ５を強制開弁する技術であるため、クランキング中に空燃比が悪化する不具合がない。このため、始動時間が延長する不具合がなく、また始動時に大量のスモークが発生する不具合も回避できる。
【００３６】
［変形例］
上記の実施例では、ＥＧＲバルブ５の開度を調整するアクチュエータの一例としてリニアソレノイド１０を用いたが、他に負圧アクチュエータ、電動モータなど、他のアクチュエータを用いても良い。
上記の実施例では、ＥＧＲバルブ５の実開度を検出する一例として弁体９の動きに連動するリフトセンサ１５を用いたが、吸入空気量などからＥＧＲバルブ５の実開度を検出するように設けても良い。
【図面の簡単な説明】
【図１】ＥＧＲ装置の概略図である。
【図２】ＥＧＲバルブの断面図である。
【図３】ＥＧＲバルブの固着を解消する制御のフローチャートである。
【図４】ＥＧＲバルブの固着を解消する作動を説明するグラフである。
【符号の説明】
１ エンジン
２ 吸気管
３ 排気管
４ ＥＧＲ配管
５ ＥＧＲバルブ
６ ＥＣＵ（制御装置）
１０ リニアソレノイド（アクチュエータ）
１５ リフトセンサ（ＥＧＲバルブの実開度を検出する手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an EGR (exhaust gas recirculation) device that returns part of engine exhaust gas to the intake side.
[0002]
[Prior art]
In recent years, EGR devices have become important under the current situation where exhaust regulations are becoming strict, and it is necessary to control the opening of the EGR valve from a small valve opening to a large valve opening depending on the operating state of the engine. Yes.
For example, in a diesel engine, exhaust gas is returned to the intake side for the purpose of reducing exhaust gas during idling. However, since the intake negative pressure is low and the exhaust pressure is low in the idling state, a necessary amount of exhaust gas is sent to the intake side. In order to return, the opening degree of the EGR valve is increased. At this time, there are cases where the particulates containing oil adhere to the valve seat or the like of the EGR valve and the EGR valve does not open due to the adhering particulates (closed valve fixing).
[0003]
Here, in an EGR device that varies the opening of the EGR valve, the actual opening of the EGR valve is read from the valve lift amount, the intake air amount, etc., and feedback control is performed so that the actual opening becomes the target opening. Yes.
For this reason, conventionally, when the EGR valve is closed by the particulate adhering to the valve seat or the like, the valve opening command value of the EGR valve gradually increases. When the driving force necessary for opening the valve is reached, the EGR valve is opened.
For this reason, a valve opening delay from when the opening instruction is given to the EGR valve until the valve is actually opened occurs. That is, if the valve is stuck, there is a problem that the time during which an appropriate EGR amount cannot be obtained becomes long.
[0004]
Further, since the actual opening becomes larger than the target opening after the sticking is released by the above-described operation, the actual opening is subsequently reduced by feedback control. That is, conventionally, since the actual opening overshooted to eliminate the sticking is brought close to the target opening by feedback control, it takes time to reach the target opening after the sticking is released.
[0005]
As a technique for preventing the EGR valve from closing and closing, the EGR valve actuator (linear) is used after the ignition switch is turned on (or the starter switch is turned on) and before the normal opening control of the EGR valve is started. A technique for forcibly energizing a solenoid or the like to eliminate sticking of the closed valve is known (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-7-293355
[Problems to be solved by the invention]
In the technique disclosed in Patent Document 1, the EGR is performed for a predetermined time or until the release of the sticking is detected by a sensor after the ignition switch is turned on (or the starter switch is turned on) for starting the engine. This technology forcibly opens the valve.
For this reason, the EGR valve is forcibly opened during cranking, the proportion of the unburned gas in the air-fuel mixture sucked into the combustion chamber during cranking increases, and conversely the proportion of air decreases. Due to the deterioration of the air-fuel ratio, the ignitability at the time of starting decreases, so the starting time from the start of starting (operation of the ignition switch) to the complete explosion of the engine becomes longer, and a large amount of smoke is generated at the time of starting. End up.
[0008]
In order to avoid deterioration of the engine start performance, the EGR valve can be forcibly opened from the ignition switch ON to cranking start (engine rotation start), but the EGR valve is forcibly opened. The time to speak is extremely short. Then, even if the EGR valve is fixed, the execution time of forced valve opening becomes extremely short, so that the possibility that the fixed release cannot be released increases.
[0009]
Here, in the technique disclosed in Patent Document 1, when the release of the EGR valve sticking is not detected at the start of the engine, the start of the normal opening control is postponed even after the start of the engine is completed. A technique for forcibly opening a valve by forcibly energizing is disclosed.
However, even with this technology, the EGR valve is still forced open even during cranking before forced energization is performed again, and the start-up time is reduced due to the deterioration of the air-fuel ratio during cranking. As it becomes longer, a large amount of smoke is generated at start-up.
[0010]
OBJECT OF THE INVENTION
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an EGR device that can release the EGR valve from adhering without deteriorating the starting performance of the engine.
[0011]
[Means for Solving the Problems]
[Means of Claim 1]
In the first aspect of the invention, the sticking detection means is provided so as to detect the sticking of the EGR valve closed during engine operation after the start of the engine is completed, and the sticking detection means detects the sticking of the EGR valve closed. Then, during the engine operation after the completion of the engine start, the driving force necessary for opening the valve is applied to the actuator to forcibly open the valve. For this reason, when the EGR valve is fixedly closed, the EGR valve can be opened quickly.
As described above, even when the EGR valve is stuck closed, the valve closing sticking is quickly released, so that an appropriate EGR amount can be obtained quickly.
[0012]
Further, in the technology for forcibly opening the EGR valve at the time of start-up (before the complete explosion of the engine) shown in Patent Document 1, the start time of the engine becomes longer due to the deterioration of the air-fuel ratio during cranking, and a large amount of smoke A malfunction occurs.
On the other hand, the invention according to claim 1 is a technique for forcibly opening the EGR valve when it recognizes that the EGR valve is closed during engine operation after the completion of engine startup. There are no worsening defects. For this reason, there is no problem that the starting time is extended, and the problem that a large amount of smoke occurs at the time of starting can be avoided.
Further, even when the sticking detection means detects that the EGR valve is closed, when the engine speed is equal to or higher than a predetermined speed and the load on the engine is equal to or higher than the predetermined load, the forced valve opening operation is not executed. Provide.
By providing in this way, there is no problem that the EGR amount changes abruptly when the engine torque is large and the torque changes abruptly.
[0013]
[Means of claim 2]
When the difference between the target opening of the EGR valve and the actual opening is equal to or greater than a predetermined value and the target opening of the EGR valve is equal to or greater than a predetermined value, the EGR valve closed sticking is detected. It may be provided as follows.
[0014]
[Means of claim 3]
When the difference between the target opening of the EGR valve and the actual opening is equal to or greater than a certain value and the target opening of the EGR valve is equal to or greater than a predetermined value, the EGR valve You may provide so that valve closing adhesion may be detected.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described using examples and modifications.
[Example]
An EGR apparatus mounted on a diesel engine or the like will be described with reference to FIG.
The EGR device includes an EGR valve 5 provided in an EGR pipe 4 communicating the intake pipe 2 and the exhaust pipe 3 of the engine 1 and an ECU 6 (an abbreviation of engine control unit) for adjusting the opening degree of the EGR valve 5. And corresponds to a control device).
[0019]
As shown in the cross-sectional view of FIG. 2, the EGR valve 5 includes two valve seats 8 provided on a partition wall 7 that partitions a pipe interior 4 a communicating with the intake pipe 2 and a pipe interior 4 b communicating with the exhaust pipe 3. The two valve bodies 9 are driven by a linear solenoid 10 (an example of an actuator). This linear solenoid 10 is duty ratio controlled by the ECU 6 to adjust the opening degree of the two valve bodies 9 (corresponding to the degree of communication of the EGR pipe 4) in the range of 0% to 100%.
[0020]
The ECU 6 controls the engine 1 (including control of the EGR valve 5) in accordance with the driving state of the vehicle and receives outputs from various sensors in order to detect the driving state.
As an example of sensors output to the ECU 6, as shown in FIG. 1, an airflow sensor 11 that detects the amount of intake air flowing through the intake pipe 2, a slot position sensor 12 that detects the accelerator opening operated by the occupant, There are an engine speed sensor 13 for detecting the engine speed, a water temperature sensor 14 for detecting the coolant temperature of the engine 1, a lift sensor 15 for directly detecting the opening degree of the EGR valve 5, and the like.
[0021]
The ECU 6 calculates a target lift (corresponding to the target opening) of the EGR valve 5 from a map, a calculation formula, or the like based on the driving state of the vehicle detected by the sensors. Feedback control is provided so as to coincide with the actual lift (corresponding to the actual opening) detected by the sensor 15.
[0022]
Here, since the exhaust gas returned to the intake pipe 2 by the EGR valve 5 passes through the valve seat 8 shown in FIG. 2, the particulates contained in the exhaust gas are transferred to the valve seat 8 and the valve body 9. Adhere to. In particular, in a low load such as an idle state, a large amount of EGR is required and the exhaust gas temperature is low, so that the particulates in the exhaust gas contain a large amount of oil.
For this reason, there is a possibility that the valve body 9 is fixedly closed by the particulates containing the oil adhering to the valve seat 8 and the valve body 9.
[0023]
Therefore, the ECU 6 performs the EGR valve 5 while the engine is running after the engine 1 is started (when the starter switch is OFF and when cranking is stopped) (when the rotational speed of the engine 1 is higher than the rotational speed due to cranking). There is provided sticking detection means (a program for sticking detection) for detecting sticking of the valve.
Then, when this sticking detection means detects that the EGR valve 5 is closed, the ECU 6 temporarily stops normal feedback control during engine operation, and the driving force required to open the linear solenoid 10 (this embodiment) In this case, the valve is forcibly opened by giving a duty ratio of 100%, and when the valve opening is confirmed by the lift sensor 15, the normal feedback control is restored.
[0024]
The sticking detection means in this embodiment is: (1) The difference between the target lift of the EGR valve 5 calculated by the ECU 6 and the actual lift detected by the lift sensor 15 is equal to or greater than a certain value (target lift−actual lift ≧ constant value); (2) When the target lift of the EGR valve 5 calculated by the ECU 6 is equal to or greater than a predetermined value (target lift ≧ predetermined value), and (3) the above conditions (1) and (2) are continued for a predetermined time or longer ((1) , (2) duration ≧ predetermined time), the EGR valve 5 is detected to be closed.
[0025]
In addition, the ECU 6 performs the above-described forced valve opening (after outputting a duty ratio of 100%, which is a fully open command to the linear solenoid 10), and (4) the actual lift detected by the lift sensor 15 has reached a predetermined lift. At the time (actual lift ≧ predetermined lift), the forced opening is stopped and the normal feedback control is resumed.
However, even when the sticking detection means detects that the EGR valve 5 is stuck closed, the ECU 6 (5) The rotational speed of the engine 1 is equal to or higher than the predetermined speed, and (6) the load applied to the engine 1 is predetermined. It is provided so that the forced valve opening operation is not executed when the load is greater than (for example, when the fuel injection amount is greater than or equal to a predetermined injection amount). As a result, when the torque of the engine 1 is large, the EGR amount changes abruptly to prevent the drivability from deteriorating.
[0026]
On the other hand, the ECU 6 detects that the EGR valve 5 is closed and starts the forced opening. When the EGR valve 5 is not opened for a predetermined time, the ECU 6 stops the forced opening and stops the EGR valve. A program for generating 5 abnormal signals is made.
When the abnormality signal of the EGR valve 5 is generated, the diagnosis logic of the EGR valve 5 programmed in the ECU 6 is activated to recognize that the abnormality of the EGR valve 5 has occurred, and warn the occupant with a warning lamp or the like. Is provided.
[0027]
Next, the control of the ECU 6 will be described based on the flowchart of FIG.
In this control flow, first, it is determined whether or not the engine is operating after the start of the engine 1 is completed (step S1). As a specific example, whether or not the ignition switch (IG switch) of the key switch is ON and the rotational speed of the engine 1 is higher than a predetermined rotational speed (rotational speed during cranking). Judgment is made. If this determination is NO, the process returns.
[0028]
If the decision result in the step S1 is YES, it is judged whether or not the control of the EGR valve 5 is being executed (step S2). If this determination is NO, the process returns. If the determination result in step S2 is YES, it is determined whether or not the valve sticking flag is set (step S3).
If the determination result in step S3 is YES, it is determined whether the above-mentioned (1) and (2) are established (step S4). If the determination result in step S4 is NO, it is detected that the EGR valve 5 is operating normally (step S5), and then the process returns.
[0029]
If the decision result in the step S4 is YES, it is judged whether or not the above-mentioned conditions (1) and (2) are continued for a predetermined time (step S6). If the determination result in step S6 is NO, the process returns. If the determination result in step S6 is YES, a valve sticking flag is set (step S7), and then the process returns.
If the determination result in step S3 is NO, that is, if the flag is set in step S7, it is determined whether or not the above-mentioned (4) is established (step S8). If the determination result in step S8 is YES, it is determined that the valve sticking has been eliminated, and the process proceeds to step S5.
[0030]
If the decision result in the step S8 is NO, it is judged whether or not the above (5) and (6) are established (step S9). If the determination result in step S9 is YES, a 100% maximum duty is output to the EGR valve 5 (step S10), and then the process returns.
If the determination result in step S9 is NO, the routine returns without performing the forced valve opening operation to prevent a problem that the drivability deteriorates due to a rapid change in the EGR amount when the torque of the engine 1 is large.
[0031]
Next, the duty change given to the EGR valve 5 and the change in the opening degree of the EGR valve 5 when the EGR valve 5 is stuck during the engine operation after the completion of the start of the engine 1 are shown in the graph of FIG. To explain.
When the target lift of the ECU 6 calculated according to the operating state of the engine 1 rises as indicated by the broken line A, the duty ratio given to the EGR valve 5 rises as indicated by the solid line B along with the rise.
[0032]
When the EGR valve 5 is stuck, even if the target lift increases as indicated by the broken line A, the actual lift does not increase as indicated by the solid line C.
The difference between the target lift and the actual lift is a certain value or more (see (1) in the figure), the target lift is more than a predetermined value (see (2) in the figure), and this state continues for a predetermined time or more (see FIG. In the middle (3), the ECU 6 detects that the EGR valve 5 is closed.
Then, the ECU 6 temporarily stops normal feedback control and outputs a duty ratio of 100% to the EGR valve 5.
[0033]
When the full opening instruction is given to the EGR valve 5, a large opening force is generated in the EGR valve 5. When the EGR valve 5 is released from the closed state, the actual lift starts to rise as indicated by the solid line C.
Then, when the actual lift reaches a predetermined lift (see (4) in the figure), the forced valve opening is stopped and the normal feedback control is resumed.
[0034]
As shown in the above operation, in the EGR device of the present embodiment, it is necessary to open the EGR valve 5 when it is detected that the EGR valve 5 is closed during the engine operation after the start of the engine 1 is completed. Since the valve is forcibly opened by giving a sufficient driving force (duty ratio 100%), it is possible to release the closed valve sticking during engine operation in a short time. As described above, even when the EGR valve 5 is stuck closed, the valve closing sticking is quickly released, so that an appropriate EGR amount can be obtained quickly.
[0035]
Further, in the technology for forcibly opening the EGR valve 5 at the time of start-up (before the complete explosion of the engine 1) shown in Patent Document 1, the EGR valve 5 is forcibly opened during cranking. As the air-fuel ratio deteriorates, the starting time of the engine 1 becomes longer, and there is a problem that a large amount of smoke is generated. On the other hand, since the EGR valve 5 is forcibly opened when it is recognized that the EGR valve 5 is closed during engine operation after the start of the engine 1 is completed, the air-fuel ratio deteriorates during cranking. Absent. For this reason, there is no problem that the starting time is extended, and the problem that a large amount of smoke occurs at the time of starting can be avoided.
[0036]
[Modification]
In the above embodiment, the linear solenoid 10 is used as an example of an actuator for adjusting the opening degree of the EGR valve 5, but other actuators such as a negative pressure actuator and an electric motor may be used.
In the above embodiment, the lift sensor 15 interlocked with the movement of the valve body 9 is used as an example of detecting the actual opening of the EGR valve 5, but the actual opening of the EGR valve 5 is detected from the intake air amount or the like. May be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view of an EGR device.
FIG. 2 is a cross-sectional view of an EGR valve.
FIG. 3 is a flowchart of control for eliminating sticking of an EGR valve.
FIG. 4 is a graph for explaining the operation for canceling the sticking of the EGR valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Intake pipe 3 Exhaust pipe 4 EGR piping 5 EGR valve 6 ECU (control apparatus)
10 Linear solenoid (actuator)
15 Lift sensor (means for detecting the actual opening of the EGR valve)

Claims (3)

エンジンの吸気管と排気管を連通するＥＧＲ配管に設けられ、このＥＧＲ配管の連通度合をアクチュエータによって調整可能なＥＧＲバルブと、
前記エンジンの運転状態に応じて前記アクチュエータを制御することにより、前記ＥＧＲバルブの開度を調整する制御装置と、
を備えるＥＧＲ装置であって、
前記制御装置は、
前記エンジンの始動完了後のエンジン運転中に、前記アクチュエータに開弁指令が与えられても前記ＥＧＲバルブの弁体がバルブシートに着座した状態でリフトが成されない閉弁固着を検出する固着検出手段を備え、
この固着検出手段が前記ＥＧＲバルブの閉弁固着を検出すると、前記エンジンの始動完了後のエンジン運転中に前記アクチュエータへ開弁に必要な駆動力を与えて強制開弁するように設けられ、
前記固着検出手段が前記ＥＧＲバルブの閉弁固着を検出して前記強制開弁を実行して前記ＥＧＲバルブの開弁が認められた時には前記強制開弁の動作から前記ＥＧＲバルブの実開度を目標開度とする通常制御に復帰し、
前記固着検出手段が前記ＥＧＲバルブの閉弁固着を検出して前記強制開弁を実行した際、所定時間に亘って前記ＥＧＲバルブの開弁が認められない時には前記強制開弁を停止して前記ＥＧＲバルブの異常信号を発生し、
前記固着検出手段が前記ＥＧＲバルブの閉弁固着を検出しても、前記エンジンの回転数が所定回転以上で、且つ前記エンジンにかかる負荷が所定負荷以上の時には前記強制開弁の動作を実行しないように設けられたことを特徴とするＥＧＲ装置。An EGR valve that is provided in an EGR pipe that connects the intake pipe and the exhaust pipe of the engine, and the degree of communication of the EGR pipe can be adjusted by an actuator;
A control device that adjusts the opening of the EGR valve by controlling the actuator according to the operating state of the engine;
An EGR device comprising:
The controller is
During engine operation after completion of engine startup, even if a valve opening command is given to the actuator, a sticking detection means for detecting valve closing sticking that does not lift when the valve body of the EGR valve is seated on a valve seat With
When the sticking detection means detects that the EGR valve is stuck closed, the actuator is provided so as to force the valve to open by applying a driving force necessary for opening the actuator during the engine operation after the completion of the engine start,
When the sticking detection means detects that the EGR valve is closed and executes the forced opening, when the opening of the EGR valve is recognized, the actual opening degree of the EGR valve is determined from the operation of the forced opening. Return to normal control with the target opening,
When the sticking detection means detects that the EGR valve is closed and executes the forced opening, when the EGR valve is not opened for a predetermined time, the forced opening is stopped and the forced opening is stopped. Generate an EGR valve error signal ,
Even if the sticking detection means detects that the EGR valve is closed, the forced valve opening operation is not executed when the engine speed is equal to or higher than a predetermined speed and the load on the engine is equal to or higher than the predetermined load. An EGR device characterized by being provided as follows . 請求項１に記載のＥＧＲ装置において、
前記固着検出手段は、前記ＥＧＲバルブの目標開度と実開度の差が一定値以上で、且つ前記ＥＧＲバルブの目標開度が所定値以上の時に、前記ＥＧＲバルブの閉弁固着を検出することを特徴とするＥＧＲ装置。The EGR device according to claim 1,
The sticking detection means detects that the EGR valve is closed when the difference between the target opening of the EGR valve and the actual opening is a predetermined value or more and the target opening of the EGR valve is a predetermined value or more. An EGR device characterized by that. 請求項１に記載のＥＧＲ装置において、
前記固着検出手段は、前記ＥＧＲバルブの目標開度と実開度の差が一定値以上で、且つ前記ＥＧＲバルブの目標開度が所定値以上の状態が所定時間以上続く時に、前記ＥＧＲバルブの閉弁固着を検出することを特徴とするＥＧＲ装置。The EGR device according to claim 1,
When the difference between the target opening of the EGR valve and the actual opening is equal to or greater than a predetermined value and the target opening of the EGR valve is equal to or greater than a predetermined value for a predetermined time or longer, the sticking detection means An EGR device that detects valve-sticking adhesion.
JP2003066688A 2002-05-24 2003-03-12 EGR device Expired - Fee Related JP4117472B2 (en)

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JP2007255251A (en) * 2006-03-22 2007-10-04 Nissan Diesel Motor Co Ltd Device for and method of determining failure of egr control valve
JP4736978B2 (en) * 2006-06-29 2011-07-27 トヨタ自動車株式会社 Exhaust gas recirculation device for internal combustion engine
JP2009544896A (en) * 2006-07-25 2009-12-17 ボーグワーナー・インコーポレーテッド Control algorithm for releasing the EGR valve from contamination
JP2009287392A (en) * 2006-09-15 2009-12-10 Mitsubishi Electric Corp Control device for exhaust gas recirculation valve
JP2008291747A (en) * 2007-05-24 2008-12-04 Toyota Motor Corp Diagnostic device
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JP5393506B2 (en) * 2010-01-27 2014-01-22 三菱重工業株式会社 Control device and control method for control valve used in engine intake system
JP6031841B2 (en) * 2012-06-14 2016-11-24 いすゞ自動車株式会社 Method for cleaning EGR valve of internal combustion engine and internal combustion engine
JP2014034921A (en) * 2012-08-08 2014-02-24 Denso Corp Control device of internal combustion engine
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