JP3647250B2 - EGR device - Google Patents

EGR device Download PDF

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Publication number
JP3647250B2
JP3647250B2 JP06671998A JP6671998A JP3647250B2 JP 3647250 B2 JP3647250 B2 JP 3647250B2 JP 06671998 A JP06671998 A JP 06671998A JP 6671998 A JP6671998 A JP 6671998A JP 3647250 B2 JP3647250 B2 JP 3647250B2
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passage
egr
intake
egr cooler
engine
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JPH11257167A (en
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孝幸 土屋
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UD Trucks Corp
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UD Trucks Corp
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    • 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
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/35—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with means for cleaning or treating the recirculated gases, e.g. catalysts, condensate traps, particle filters or heaters
    • 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
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/04—EGR systems specially adapted for supercharged engines with a single turbocharger
    • F02M26/05—High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust-Gas Circulating Devices (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Description

【０００１】
【発明の属する技術分野】
この発明はエンジンのＥＧＲ装置に関する。
【０００２】
【従来の技術】
エンジンのＮＯｘ対策として排気ガスの一部を吸気側に還流するＥＧＲ装置がよく知られている。このうち、ＥＧＲガスの密度を高めるため、ＥＧＲガスを冷却するＥＧＲクーラ（熱交換器）を備えるものがある（特開平９ー１３７７５４号公報，特開平９ー２８０１１８号公報）。
【０００３】
その一例を図７に説明すると、１はエンジンの吸気通路、２は同じく排気通路であり、これらを連通するＥＧＲ通路３が設けられ、その通路途中にＥＧＲ弁４とＥＧＲクーラ５が介装される。ＥＧＲ弁４が開くと、エンジンの排気の一部が還流され、このＥＧＲガスをＥＧＲクーラ５が冷却する。そのため、吸入空気量を確保しつつ、ＥＧＲ率を高めることができる。
【０００４】
【発明が解決しようとする課題】
ＥＧＲクーラ５において、ＥＧＲガスの通路部分は冷却されるため、ＥＧＲガスの凝縮水などにより、煤などの付着しやすい条件下にあり、通路に煤などが付着すると、圧力損失の増加や冷却効率の低下およびこれらに伴うＥＧＲ率の低下を招くてしまう。つまり、良好なＥＧＲ性能を長く安定的に維持できないという不具合が考えられる。
【０００５】
この発明は、このような問題点の有効な対策手段の提供を目的とする。
【０００６】
【課題を解決するための手段】
第１の発明は、エンジンの吸気通路にバイパス通路を形成し、バイパス通路の途中にＥＧＲクーラを介装する一方、バイパス通路のＥＧＲクーラ上流側をエンジンの排気通路に連通するＥＧＲ通路と、吸気通路の上流側に対してその下流側を開いてバイパス通路の入口を閉じるＡポジションと同じく吸気通路の下流側を開いてバイパス通路の入口を開くＢポジションと同じく吸気通路の下流側を閉じてバイパス通路の入口を開くＣポジションとの３位置に切り替わる通路切換弁と、ＥＧＲ通路を開閉するＥＧＲ弁と、通路切換弁およびＥＧＲ弁をエンジン運転状態に応じて制御するコントローラと、を設けてなり、コントローラはエンジン運転状態がＥＧＲクーラに吸気の全量を流入させられる非ＥＧＲ領域にあることを判定すると通路切換弁をＣポジションに制御する手段を備えたことを特徴とする。
【０００７】
第２の発明は、第１の発明において、吸気通路の上流側に過給機を備えたことを特徴とする。
【０００９】
【発明の効果】
第１の発明においては、エンジン運転状態に応じて吸入空気の流れを制御することができる。通路切換弁が吸気通路の上流側に対してバイパス通路の入口を閉じてその下流側の吸気通路を開くと、吸入空気は吸気通路のみを流れ、この状態でＥＧＲ弁が開くと、バイパス通路のＥＧＲクーラには、ＥＧＲガスのみが流れる。通路切換弁が吸気通路の上流側に対してバイパス通路の入口を開いてその下流側の吸気通路も開くと、吸入空気は吸気通路とバイパス通路との両方を流れ、この状態でＥＧＲ弁が開くと、バイパス通路のＥＧＲクーラには、吸入空気の一部とＥＧＲガスの全量が流れる。通路切換弁が吸気通路の上流側に対してバイパス通路の入口を開いてその下流側の吸気通路を閉じると、吸入空気はバイパス通路のみに流れ、この状態でＥＧＲ弁が閉じると、バイパス通路のＥＧＲクーラには、吸入空気のみが流れる。このような制御を行うことにより、ＥＧＲが行われるときにも、吸入空気（新気）の一部がＥＧＲクーラを通過するため、ＥＧＲクーラの通路部分に煤などが付着しづらくなる。仮に煤などが付着しても，非ＥＧＲの特定領域において、新気の全量がＥＧＲクーラを通過するため、煤などの付着物を効果的に吹き飛ばし、エンジンで再燃焼することができる。
【００１０】
第２の発明においては、過給気がＥＧＲクーラを通過するため、ＥＧＲクーラの通路部分における、煤などの付着防止およびその除去作用（吹き飛ばし効果）を促進することができる。
【００１２】
【発明の実施の形態】
図１は第１の実施形態を表すものであり、エンジンの吸気通路１０において、吸気マニホールド１０ａ上流にＥＧＲクーラ１１が介装される。１２はＥＧＲ通路であり、エンジンの排気通路２０（この場合、排気マニホールド２０ａ）を吸気通路１０のＥＧＲクーラ１１上流側に連通する。そして、ＥＧＲ通路１２を開閉するＥＧＲ弁１３と、ＥＧＲ弁１３をエンジン運転状態に応じて制御するコントローラ（図示せず）と、が設けられる。
【００１３】
ＥＧＲクーラ１１として例えば水冷式が採用され、図示しないが、筒形の胴体とその内部を軸方向へ貫通する複数または単数の冷却管（吸気通路１０を形成する）とからなり、その回りに胴体で囲われる流路が形成される。エンジンの冷却水がこの流路を経由して循環するように配管され、冷却管を通過する流体とその回りの流路を通過する冷却水との間で熱交換を行うようになっている。
【００１４】
このような構成により、ＥＧＲ弁１３が開くと、ＥＧＲガスは吸気通路へＥＧＲ通路１２を通して供給され、吸入空気（新気）とともにＥＧＲクーラ１１を通過してエンジンへと供給される。エンジンの吸気通路１０にＥＧＲクーラ１１を備えるため、ＥＧＲが行われるときにも、吸入空気（新気）がＥＧＲクーラ１１を通過するため、ＥＧＲクーラ１１の通路部分に煤などの付着しづらくなる。また、仮に煤などが付着しても、ＥＧＲが停止すると、新気のみがＥＧＲクーラ１１を通過するため、煤などの付着物を吹き飛ばし、エンジンで再燃焼することができる。
【００１５】
その結果、ＥＧＲクーラ１１において、その通路部分に煤などが付着しすぎることはなく、煤などの付着物に原因する、圧力損失の増加や冷却効率の低下およびこれらに伴うＥＧＲ率の低下が防止されるため、良好なＥＧＲ性能を安定的に維持できるようになる。
【００１６】
図２は第２の実施形態を表すものであり、エンジンの吸気通路１０において、吸気マニホールド１０ａ上流にバイパス通路１４が形成され、バイパス通路１４の途中にＥＧＲクーラ１１が介装される。ＥＧＲ通路１２は、エンジンの排気通路２０（この場合、排気マニホールド２０ａ）をバイパス通路１４のＥＧＲクーラ１１上流に連通する。
【００１７】
吸気通路１０とバイパス通路１４の入口側との接続部には、吸気通路１０の上流側に対してバイパス通路１４およびその下流側の吸気通路１０を選択的に開閉するように吸入空気の流れを制御する通路切換弁１５が介装される。１３はＥＧＲ通路１２を開閉するＥＧＲ弁である。
【００１８】
通路切換弁１５は、吸気通路１０の上流側に対してバイパス通路１４を閉じてその下流側の吸気通路１０を開くＡポジションと、吸気通路１０の上流側に対してバイパス通路１４を開いてその下流側の吸気通路１０も開くＢポジションと、吸気通路１０の上流側に対してバイパス通路１４を開いてその下流側の吸気通路１０を閉じるＣポジションと、これらポジションを選択的に切り替える作動部（図示せず）と、を備える。
【００１９】
通路切換弁１５およびＥＧＲ弁１３をエンジン運転状態に応じて制御するのがコントローラ１６（ＣＰＵ）であり、そのメモリに図３のような制御マップが格納される。制御マップには、ＥＧＲを行う運転領域Ａ，Ｂと行わない運転領域Ｃ，Ｄ，Ｅのほか、エンジン性能にＥＧＲクーラ１１の圧力損失が及ぼす影響などについての考察に基づいて、吸入空気の一部をＥＧＲクーラ１１へ流入させられる運転領域Ｂ，Ｃと、吸入空気の全量をＥＧＲクーラ１１へ流入させられる運転領域Ｄと、吸入空気のＥＧＲクーラへの流入を不可とする運転領域Ａ，Ｅが設定される。１７はエンジン運転状態を検出する手段（アクセル開度センサ，エンジン回転センサ）であり、その検出信号はコントローラ１６に入力される。
【００２０】
図はコントローラ１６の制御内容を説明するフローチャートであり、ステップ１でエンジン運転状態の検出信号に基づいて、ＥＧＲを行う運転領域Ａ，Ｂかどうかを判定する。ＥＧＲを行う運転領域Ａ，Ｂのときは、ステップ２へ進む一方、ＥＧＲを行わない運転領域Ｃ，Ｄ，Ｅのときは、ステップ１１へ飛ぶ。
【００２１】
ステップ２では、吸入空気のＥＧＲクーラ１１への流入を可とする運転領域Ｂがどうかを判定する。吸入空気の流入が可（ステップ２の判定がＹＥＳ）のときは、ステップ３へ進み、通路切換弁１５をＢポジションに切り換える。ステップ４において、通路切換弁１５が吸気通路の上流側に対してバイパス通路１４を開いてその下流側の吸気通路１０を開くと、吸入空気は吸気通路１０とバイパス通路１４の両方を流れる。そして、ステップ５でＥＧＲ弁１３を開くと、ステップ６において、バイパス通路１４のＥＧＲクーラ１１には、吸入空気とＥＧＲガスが流れる。
【００２２】
ステップ２の判定がＮＯ（吸入空気のＥＧＲクーラ１１への流入を不可とする運転領域Ａ）のときは、ステップ７へ飛び、通路切換弁１５をＡポジションに切り替える。ステップ８において、通路切換弁１５が吸気通路１０の上流側に対してバイパス通路１４を閉じてその下流側の吸気通路１０を開くと、吸入空気は吸気通路１０のみを流れる。そして、ステップ９でＥＧＲ弁１３を開くと、ステップ１０において、バイパス通路１４のＥＧＲクーラ１１には、ＥＧＲガスのみが流れる。
【００２３】
ＥＧＲを行わない運転領域Ｃ，Ｄ，Ｅ（ステップ１の判定がＮＯ）のときは、ステップ１１において、吸入空気のＥＧＲクーラ１１への流入を可とする運転領域Ｃ，Ｄがどうかを判定する。その判定がＹＥＳのときは、ステップ１２へ進み、吸入空気の全量をＥＧＲクーラ１１へ流入させるかどうかを判定する。
【００２４】
ステップ１２の判定がＹＥＳ（吸入空気の全量をＥＧＲクーラ１１へ流入させられる運転領域Ｄ）のときは、ステップ１３で通路切換弁１５をＣポジションに切り換える。ステップ１４において、通路切換弁１５が吸気通路１０の上流側に対してバイパス通路１４を開いてその下流側の吸気通路１０を閉じると、吸入空気はバイパス通路１４のみを流れる。そして、ステップ１５でＥＧＲ弁１３を閉じると、ＥＧＲガスの供給が停止され、ステップ１６において、バイパス通路１４のＥＧＲクーラ１１には、吸入空気の全量が流れる。
【００２５】
ステップの判定がＮＯ（吸入空気の一部をＥＧＲクーラ１１へ流入させられる運転領域Ｃ）のときは、ステップ１７で通路切換弁１５をＢポジションに切り換える。ステップ１６において、通路切換弁１５が吸気通路１０の上流側に対してバイパス通路１４を開いてその下流側の吸気通路１０を開くと、吸入空気は吸気通路１０とバイパス通路１４の両方を流れる。そして、ステップ１９でＥＧＲ弁１３を閉じると、ＥＧＲガスの供給が停止され、ステップ２０において、バイパス通路１４のＥＧＲクーラ１１には、吸入空気の一部が流れる。
【００２６】
ステップ１１において、吸入空気のＥＧＲクーラ１１への流入を不可とする運転領域Ｅを判定すると、ステップ２１へ飛び、通路切換弁１５をＡポジションに切り替える。ステップ２２において、通路切換弁１５が吸気通路１０の上流側に対してバイパス通路１４を閉じてその下流側の吸気通路１０を開くと、吸入空気は吸気通路１０のみを流れる。そして、ステップ２３でＥＧＲ弁１３を閉じると、ステップ２４において、バイパス通路１４のＥＧＲクーラ１１には、吸入空気もＥＧＲガスも流れない状態になる。
【００２７】
このような制御により、図３の運転領域Ｂで吸入空気の一部がＥＧＲクーラ１１を通過するため、ＥＧＲクーラ１１の通路部分に煤などが付着しづらくなる。また、運転領域Ａおよび運転領域Ｂにおいて、仮に煤などが付着しても、ＥＧＲの停止時に運転領域Ｄで吸入空気の全量が、運転領域Ｃで吸入空気の一部がＥＧＲクーラを通過するため、煤などの付着物を吹き飛ばし、エンジンで再燃焼することができる。
【００２８】
その結果、ＥＧＲクーラ１１の通路部分に煤などが付着しすぎるようなことがなく、煤などの付着に原因する、圧力損失の増加や冷却効率の低下およびこれらに伴うＥＧＲ率の低下が防止されるため、良好なＥＧＲ性能を安定的に維持できるようになる。
【００２９】
図５は第３の実施形態を表すものであり、エンジンの吸気通路１０に過給圧を発生させる過給機２１と、その過給気を冷却するインタクーラ２２と、が備えられる。インタクーラ２２と吸気マニホールド１０ａとの間にＥＧＲクーラ１１が介装される。エンジンの排気通路２０（この場合、排気マニホールド２０ａ）を吸気通路１０のインタクーラ２２とＥＧＲクーラ１１との間に連通するＥＧＲ通路１２と、ＥＧＲ通路１２を開閉するＥＧＲ弁１３と、ＥＧＲ弁１３をエンジン運転状態に応じて制御するコントローラ（図示せず）と、が設けられる。
【００３０】
これによると、ＥＧＲが行われるときにも、インタクーラ２２下流の過給気が、ＥＧＲクーラ１１を通過するため、自然吸気の場合に較べると、煤などの付着防止およびその除去作用（吹き飛ばし）の効果を促進できる。そのため、ＥＧＲクーラ１１の通路部分に煤などが付着しすぎるようなことなく、良好なＥＧＲ性能を安定的に維持できるようになる。また、過給機２１とインタクーラ２２により、煤などの発生量を低減しつつ、ＮＯｘの発生量も抑制できる。
【００３１】
図６は第４の実施形態を表すものであり、エンジンの吸気通路１０に過給圧を発生させる過給機２１と、その過給気を冷却するインタクーラ２２と、が備えられる。吸気通路１０のインタクーラ２２と吸気マニホールド１０ａとの間にバイパス通路１４が形成され、バイパス通路１４の途中にＥＧＲクーラ１１が介装される。エンジンの排気通路２０（この場合、排気マニホールド２０ａ）をバイパス通路１４のＥＧＲクーラ１１上流に連通するＥＧＲ通路１２と、ＥＧＲ通路１２を開閉するＥＧＲ弁１３が設けられる。
【００３２】
吸気通路１０とバイパス通路１４の入口側との接続部には、吸気通路１０の上流側に対してバイパス通路１４およびその下流側の吸気通路１０を選択的に開閉するように吸入空気の流れを制御する通路切換弁１５が介装される。１６はコントローラ（ＣＰＵ）であり、エンジン運転状態を検出する手段１７が設けられ、図３のような制御マップに基づいて、エンジン運転状態の検出信号に応じて通路切換弁１５とＥＧＲ弁１３を図４のように制御する。
【００３３】
これによると、図３の運転領域Ｂと運転領域Ｃおよび運転領域Ｄにおいて、インタクーラ２２下流の過給気が、ＥＧＲクーラ１１を通過するため、自然吸気の場合に較べると、煤などの付着防止およびその除去作用（吹き飛ばし）の効果を促進できる。そのため、ＥＧＲクーラ１１の通路部分に煤などが付着しすぎるようなことなく、良好なＥＧＲ性能を安定的に維持できるようになる。また、過給機２１とインタクーラ２２により、煤などの発生量を低減しつつ、ＮＯｘの発生量も抑制できる。
【００３４】
なお、図１，図２，図５，図６において、ＥＧＲクーラ１１は空冷式でもよく、その場合も同様の効果が得られる。
【図面の簡単な説明】
【図１】第１の実施形態を表すシステムの構成図である。
【図２】第２の実施形態を表すシステムの構成図である。
【図３】同じくコントローラの制御内容を説明する特性（マップ）図である。
【図４】同じくコントローラの制御内容を説明するフローチャートである。
【図５】第３の実施形態を表すシステムの構成図である。
【図６】第４の実施形態を表すシステムの構成図である。
【図７】従来例の説明図である。
【符号の説明】
１０ 吸気通路
１１ ＥＧＲクーラ
１２ ＥＧＲ通路
１３ ＥＧＲ弁
１４ バイパス通路
１５ 通路切換弁
１６ コントローラ
１７ エンジン運転状態検出手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an EGR device for an engine.
[0002]
[Prior art]
As an engine NOx countermeasure, an EGR device that recirculates a part of exhaust gas to the intake side is well known. Among them, there are some equipped with an EGR cooler (heat exchanger) for cooling the EGR gas in order to increase the density of the EGR gas (Japanese Patent Laid-Open Nos. 9-137754 and 9-280118).
[0003]
An example of this is illustrated in FIG. 7. Reference numeral 1 denotes an engine intake passage, reference numeral 2 denotes an exhaust passage, and an EGR passage 3 that connects these is provided, and an EGR valve 4 and an EGR cooler 5 are interposed in the passage. The When the EGR valve 4 is opened, a part of the engine exhaust is recirculated, and the EGR cooler 5 cools the EGR gas. Therefore, the EGR rate can be increased while securing the intake air amount.
[0004]
[Problems to be solved by the invention]
In the EGR cooler 5, the passage portion of the EGR gas is cooled, so that conditions such as soot easily adhere to the EGR gas condensed water. If soot adheres to the passage, the pressure loss increases and the cooling efficiency And the accompanying decrease in the EGR rate. That is, there is a problem that good EGR performance cannot be maintained stably for a long time.
[0005]
It is an object of the present invention to provide effective countermeasure means for such problems.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, a bypass passage is formed in an intake passage of an engine, and an EGR cooler is interposed in the middle of the bypass passage, while an EGR passage communicating the upstream side of the EGR cooler of the bypass passage with an exhaust passage of the engine, Same as position A, which opens the downstream side with respect to the upstream side of the passage and closes the inlet of the bypass passage, opens the downstream side of the intake passage and opens the inlet of the bypass passage, and closes the downstream side of the intake passage and bypasses. A passage switching valve that switches to three positions, the C position that opens the passage inlet, an EGR valve that opens and closes the EGR passage, and a controller that controls the passage switching valve and the EGR valve according to the engine operating state, When the controller determines that the engine operating state is in a non-EGR region where the entire amount of intake air is allowed to flow into the EGR cooler, the passage is switched. The characterized by comprising means for controlling the C position.
[0007]
The second invention is characterized in that, in the first invention, a supercharger is provided upstream of the intake passage .
[0009]
【The invention's effect】
In the first invention, the flow of intake air can be controlled in accordance with the engine operating state. When the passage switching valve closes the inlet of the bypass passage with respect to the upstream side of the intake passage and opens the intake passage downstream thereof, the intake air flows only through the intake passage. When the EGR valve opens in this state, Only EGR gas flows through the EGR cooler. When the passage switching valve opens the inlet of the bypass passage with respect to the upstream side of the intake passage and also opens the intake passage downstream thereof, the intake air flows through both the intake passage and the bypass passage, and in this state, the EGR valve opens. Then, a part of the intake air and the entire amount of EGR gas flow through the EGR cooler in the bypass passage. When the passage switching valve opens the inlet of the bypass passage with respect to the upstream side of the intake passage and closes the intake passage on the downstream side thereof, the intake air flows only into the bypass passage. When the EGR valve is closed in this state, Only the intake air flows through the EGR cooler. By performing such control, even when EGR is performed, a part of the intake air (fresh air) passes through the EGR cooler, so that it is difficult for soot and the like to adhere to the passage portion of the EGR cooler. Even if soot or the like adheres, the entire amount of fresh air passes through the EGR cooler in the non-EGR specific region, so that the attached matter such as soot can be effectively blown off and recombusted by the engine .
[0010]
In the second invention, since the supercharged air passes through the EGR cooler, it is possible to promote adhesion prevention and removal action (blow-off effect) such as soot in the passage portion of the EGR cooler .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a first embodiment, and an EGR cooler 11 is interposed upstream of an intake manifold 10a in an intake passage 10 of an engine. An EGR passage 12 communicates the engine exhaust passage 20 (in this case, the exhaust manifold 20a) to the upstream side of the EGR cooler 11 in the intake passage 10. An EGR valve 13 that opens and closes the EGR passage 12 and a controller (not shown) that controls the EGR valve 13 according to the engine operating state are provided.
[0013]
For example, a water-cooled type is adopted as the EGR cooler 11, and although it is not shown in the figure, it is composed of a cylindrical body and a plurality of or a single cooling pipe (forming the intake passage 10) penetrating the inside thereof in the axial direction. A flow path surrounded by is formed. The cooling water of the engine is piped so as to circulate through this flow path, and heat exchange is performed between the fluid passing through the cooling pipe and the cooling water passing through the flow path around the cooling pipe.
[0014]
With such a configuration, when the EGR valve 13 is opened, the EGR gas is supplied to the intake passage through the EGR passage 12, and is supplied to the engine through the EGR cooler 11 together with the intake air (fresh air). Since the EGR cooler 11 is provided in the intake passage 10 of the engine, intake air (fresh air) passes through the EGR cooler 11 even when EGR is performed, so that it is difficult for the soot and the like to adhere to the passage portion of the EGR cooler 11. . Further, even if soot or the like adheres, when EGR stops, only fresh air passes through the EGR cooler 11, so that the attached matter such as soot can be blown off and recombusted by the engine.
[0015]
As a result, in the EGR cooler 11, soot or the like does not adhere too much to the passage portion, and an increase in pressure loss, a decrease in cooling efficiency and a concomitant reduction in the EGR rate caused by the deposits such as soot are prevented. Therefore, good EGR performance can be stably maintained.
[0016]
FIG. 2 shows a second embodiment. In the engine intake passage 10, a bypass passage 14 is formed upstream of the intake manifold 10 a, and an EGR cooler 11 is interposed in the bypass passage 14. The EGR passage 12 connects the engine exhaust passage 20 (in this case, the exhaust manifold 20a) to the EGR cooler 11 upstream of the bypass passage 14.
[0017]
At the connecting portion between the intake passage 10 and the inlet side of the bypass passage 14, the flow of intake air is provided so as to selectively open and close the bypass passage 14 and the intake passage 10 downstream thereof with respect to the upstream side of the intake passage 10. A passage switching valve 15 to be controlled is interposed. Reference numeral 13 denotes an EGR valve that opens and closes the EGR passage 12.
[0018]
The passage switching valve 15 has an A position in which the bypass passage 14 is closed with respect to the upstream side of the intake passage 10 and the intake passage 10 on the downstream side is opened, and the bypass passage 14 is opened with respect to the upstream side of the intake passage 10. A B position that also opens the intake passage 10 on the downstream side, a C position that opens the bypass passage 14 to the upstream side of the intake passage 10 and closes the intake passage 10 on the downstream side, and an operation unit that selectively switches between these positions ( (Not shown).
[0019]
The controller 16 (CPU) controls the passage switching valve 15 and the EGR valve 13 in accordance with the engine operating state, and a control map as shown in FIG. 3 is stored in its memory. In the control map, in addition to the operation areas A and B where EGR is performed and the operation areas C, D and E where the EGR is not performed, one of the intake air is based on the consideration of the influence of the pressure loss of the EGR cooler 11 on the engine performance. Operation areas B and C in which a part flows into the EGR cooler 11, an operation area D in which the entire amount of intake air flows into the EGR cooler 11, and operation areas A and E in which intake air cannot flow into the EGR cooler Is set. Reference numeral 17 denotes a means (accelerator opening sensor, engine rotation sensor) for detecting the engine operating state, and the detection signal is input to the controller 16.
[0020]
The figure is a flowchart for explaining the control contents of the controller 16. In step 1, it is determined whether or not the operation region is A or B in which EGR is performed based on the detection signal of the engine operation state. In the operation areas A and B where EGR is performed, the process proceeds to Step 2, while in the operation areas C, D and E where EGR is not performed, the process jumps to Step 11.
[0021]
In step 2, it is determined whether or not there is an operation region B in which intake air can flow into the EGR cooler 11. When the intake air is allowed to flow in (YES in step 2), the process proceeds to step 3 to switch the passage switching valve 15 to the B position. In step 4, when the passage switching valve 15 opens the bypass passage 14 to the upstream side of the intake passage and opens the intake passage 10 on the downstream side, the intake air flows through both the intake passage 10 and the bypass passage 14. When the EGR valve 13 is opened in step 5, intake air and EGR gas flow through the EGR cooler 11 in the bypass passage 14 in step 6.
[0022]
If the determination in step 2 is NO (operating region A in which intake air cannot flow into the EGR cooler 11), the routine jumps to step 7 and the passage switching valve 15 is switched to the A position. In step 8, when the passage switching valve 15 closes the bypass passage 14 with respect to the upstream side of the intake passage 10 and opens the intake passage 10 on the downstream side, the intake air flows only through the intake passage 10. When the EGR valve 13 is opened in step 9, only EGR gas flows through the EGR cooler 11 in the bypass passage 14 in step 10.
[0023]
When the operation regions C, D, and E are not used for EGR (the determination in step 1 is NO), in step 11, it is determined whether or not there are operation regions C and D that allow the intake air to flow into the EGR cooler 11. . When the determination is YES, the process proceeds to step 12 to determine whether or not the entire amount of intake air is allowed to flow into the EGR cooler 11.
[0024]
If the determination in step 12 is YES (operation region D in which the entire amount of intake air is allowed to flow into the EGR cooler 11), the passage switching valve 15 is switched to the C position in step 13. In step 14, when the passage switching valve 15 opens the bypass passage 14 with respect to the upstream side of the intake passage 10 and closes the intake passage 10 on the downstream side, the intake air flows only through the bypass passage 14. When the EGR valve 13 is closed in step 15, the supply of EGR gas is stopped. In step 16, the entire amount of intake air flows through the EGR cooler 11 in the bypass passage 14.
[0025]
When the determination of step is NO (operation region C in which a part of the intake air is allowed to flow into the EGR cooler 11), the passage switching valve 15 is switched to the B position in step 17. In step 16, when the passage switching valve 15 opens the bypass passage 14 to the upstream side of the intake passage 10 and opens the intake passage 10 on the downstream side, the intake air flows through both the intake passage 10 and the bypass passage 14. When the EGR valve 13 is closed in step 19, the supply of EGR gas is stopped. In step 20, part of the intake air flows through the EGR cooler 11 in the bypass passage 14.
[0026]
If it is determined in step 11 that the operation region E is incapable of allowing the intake air to flow into the EGR cooler 11, the process jumps to step 21 to switch the passage switching valve 15 to the A position. In step 22, when the passage switching valve 15 closes the bypass passage 14 with respect to the upstream side of the intake passage 10 and opens the intake passage 10 on the downstream side, the intake air flows only through the intake passage 10. When the EGR valve 13 is closed in step 23, in step 24, neither the intake air nor the EGR gas flows into the EGR cooler 11 of the bypass passage 14.
[0027]
Due to such control, part of the intake air passes through the EGR cooler 11 in the operation region B of FIG. 3, so that it is difficult for soot or the like to adhere to the passage portion of the EGR cooler 11. In addition, even if soot or the like adheres in the operation region A and the operation region B, the entire amount of intake air passes through the EGR cooler in the operation region D and part of the intake air in the operation region C when the EGR is stopped. Blow off deposits such as soot, and re-burn with the engine.
[0028]
As a result, soot or the like does not adhere excessively to the passage portion of the EGR cooler 11, and an increase in pressure loss, a decrease in cooling efficiency and a concomitant decrease in the EGR rate caused by the attachment of soot and the like are prevented. Therefore, good EGR performance can be stably maintained.
[0029]
FIG. 5 shows a third embodiment, which includes a supercharger 21 that generates a supercharging pressure in the intake passage 10 of the engine, and an intercooler 22 that cools the supercharged air. The EGR cooler 11 is interposed between the intercooler 22 and the intake manifold 10a. An EGR passage 12 that connects the engine exhaust passage 20 (in this case, the exhaust manifold 20a) between the intercooler 22 and the EGR cooler 11 of the intake passage 10, an EGR valve 13 that opens and closes the EGR passage 12, and an EGR valve 13 And a controller (not shown) for controlling according to the engine operating state.
[0030]
According to this, even when EGR is performed, since the supercharged air downstream of the intercooler 22 passes through the EGR cooler 11, it prevents the soot from adhering and removes it (blows off) compared to natural intake. It can promote the effect. As a result, good EGR performance can be stably maintained without excessive soot adhering to the passage portion of the EGR cooler 11. Further, the supercharger 21 and the intercooler 22 can reduce the generation amount of soot and the like, while suppressing the generation amount of NOx.
[0031]
FIG. 6 shows a fourth embodiment, which includes a supercharger 21 that generates a supercharging pressure in the intake passage 10 of the engine, and an intercooler 22 that cools the supercharged air. A bypass passage 14 is formed between the intercooler 22 of the intake passage 10 and the intake manifold 10 a, and the EGR cooler 11 is interposed in the middle of the bypass passage 14. An EGR passage 12 that connects the engine exhaust passage 20 (in this case, the exhaust manifold 20a) to the EGR cooler 11 upstream of the bypass passage 14 and an EGR valve 13 that opens and closes the EGR passage 12 are provided.
[0032]
At the connecting portion between the intake passage 10 and the inlet side of the bypass passage 14, the flow of intake air is provided so as to selectively open and close the bypass passage 14 and the intake passage 10 downstream thereof with respect to the upstream side of the intake passage 10. A passage switching valve 15 to be controlled is interposed. Reference numeral 16 denotes a controller (CPU), which is provided with means 17 for detecting the engine operating state. Based on the control map as shown in FIG. 3, the passage switching valve 15 and the EGR valve 13 are controlled according to the detection signal of the engine operating state. Control is performed as shown in FIG.
[0033]
According to this, in the operation region B, the operation region C, and the operation region D of FIG. 3, the supercharged air downstream of the intercooler 22 passes through the EGR cooler 11, so that adhesion of soot and the like is prevented compared to the case of natural intake. And the effect of the removal action (blow off) can be promoted. As a result, good EGR performance can be stably maintained without excessive soot adhering to the passage portion of the EGR cooler 11. Further, the supercharger 21 and the intercooler 22 can reduce the generation amount of soot and the like, while suppressing the generation amount of NOx.
[0034]
1, 2, 5, and 6, the EGR cooler 11 may be an air-cooled type, and in that case, the same effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a system representing a first embodiment.
FIG. 2 is a configuration diagram of a system representing a second embodiment.
FIG. 3 is a characteristic (map) diagram for explaining the control contents of the controller.
FIG. 4 is a flowchart for explaining the control contents of the controller.
FIG. 5 is a configuration diagram of a system representing a third embodiment.
FIG. 6 is a configuration diagram of a system representing a fourth embodiment.
FIG. 7 is an explanatory diagram of a conventional example.
[Explanation of symbols]
10 Intake Passage 11 EGR Cooler 12 EGR Passage 13 EGR Valve 14 Bypass Passage 15 Passage Switching Valve 16 Controller 17 Engine Operating State Detection Means

Claims (2)

エンジンの吸気通路にバイパス通路を形成し、バイパス通路の途中にＥＧＲクーラを介装する一方、バイパス通路のＥＧＲクーラ上流側をエンジンの排気通路に連通するＥＧＲ通路と、吸気通路の上流側に対してその下流側を開いてバイパス通路の入口を閉じるＡポジションと同じく吸気通路の下流側を開いてバイパス通路の入口を開くＢポジションと同じく吸気通路の下流側を閉じてバイパス通路の入口を開くＣポジションとの３位置に切り替わる通路切換弁と、ＥＧＲ通路を開閉するＥＧＲ弁と、通路切換弁およびＥＧＲ弁をエンジン運転状態に応じて制御するコントローラと、を設けてなり、コントローラはエンジン運転状態がＥＧＲクーラに吸気の全量を流入させられる非ＥＧＲ領域にあることを判定すると通路切換弁をＣポジションに制御する手段を備えたことを特徴とするＥＧＲ装置。 A bypass passage is formed in the intake passage of the engine, and an EGR cooler is interposed in the middle of the bypass passage, while the EGR passage upstream of the bypass passage communicates with the exhaust passage of the engine and the upstream side of the intake passage. Open the downstream side of the intake passage and close the inlet of the bypass passage. Similarly to the B position, open the downstream side of the intake passage and open the inlet of the bypass passage. And a controller for controlling the passage switching valve and the EGR valve in accordance with the engine operating state. The controller is configured so that the engine operating state is If it is determined that the EGR cooler is in a non-EGR region where the entire amount of intake air is allowed to flow, the passage switching valve is set to the C position. EGR apparatus characterized by comprising means for controlling the. 吸気通路の上流側に過給機を備えたことを特徴とする請求項１に記載のＥＧＲ装置。 The EGR device according to claim 1, further comprising a supercharger upstream of the intake passage .
JP06671998A 1998-03-17 1998-03-17 EGR device Expired - Fee Related JP3647250B2 (en)

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SE528881C2 (en) * 2005-07-18 2007-03-06 Scania Cv Ab Arrangement and method for recirculating exhaust gases of an internal combustion engine
JP4525544B2 (en) * 2005-09-28 2010-08-18 トヨタ自動車株式会社 Internal combustion engine with a supercharger
FR2892155B1 (en) * 2005-10-19 2007-12-14 Inst Francais Du Petrole CIRCUIT FOR SUPPLYING AT LEAST ONE FLUID OF A SUPERCHARGED MOTOR AND METHOD FOR FEEDING AT AT LEAST ONE FLUID SUCH A MOTOR
EP1957776B1 (en) * 2005-11-29 2009-03-25 Renault Trucks Exhaust gas recirculation system and method for cleaning such a system
JP2010528211A (en) * 2007-05-21 2010-08-19 ボーグワーナー・インコーポレーテッド Intake / exhaust system of combustion engine, component thereof, and operation control method thereof
FR2935024B1 (en) * 2008-08-13 2011-05-27 Renault Sas METHOD OF DEPOSITING DEPOSITS ON THERMAL EXCHANGE WALLS OF EXHAUST GAS RECIRCULATION COOLING AND INTERNAL COMBUSTION ENGINE
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