JP3695038B2 - EGR equipment with EGR cooler - Google Patents

EGR equipment with EGR cooler Download PDF

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JP3695038B2
JP3695038B2 JP01523497A JP1523497A JP3695038B2 JP 3695038 B2 JP3695038 B2 JP 3695038B2 JP 01523497 A JP01523497 A JP 01523497A JP 1523497 A JP1523497 A JP 1523497A JP 3695038 B2 JP3695038 B2 JP 3695038B2
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egr
passage
intake
pressure
branch
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JPH10213020A (en
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浩司 夏目
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Isuzu Motors Ltd
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Isuzu Motors Ltd
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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
    • F02M26/36—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with means for adding fluids other than exhaust gas to the recirculation passage; with reformers
    • 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

Description

【０００１】
【発明の属する技術分野】
本発明は、エンジンのＥＧＲにおいて、ＥＧＲクーラーでＥＧＲガスの温度を下げることにより、空気の吸入効率を向上させてエンジンの燃焼を良好に保つと共に、燃焼温度を下げて排気ガス中のＮＯｘを低減するＥＧＲクーラー付きＥＧＲ装置に関するものである。
【０００２】
【従来の技術】
ディーゼルエンジンなどの排気ガス対策において、排気ガス中のＮＯｘの排出量を低減するために、排気ガスの一部を吸気に還流することによって、燃焼温度を低く抑えて、ＮＯｘの生成を抑制するＥＧＲ（排気再循環）が有効であることが知られ、広く実用化されている。
【０００３】
このＥＧＲ装置においては、エンジンの排気通路から排気ガスを分流するＥＧＲ通路を吸気通路側に接続して、ＥＧＲ通路に設けたＥＧＲ弁でＥＧＲガスの流量を調整しながらＥＧＲを行っている。
しかし、高温のＥＧＲガスをそのまま吸気側に循環させると、高温で膨張したＥＧＲガスが吸気マニホールドに供給されることになり、吸気時のシリンダー内のＥＧＲガスが占める割合が多くなり、シリンダー内に入る空気量が低減してしまうという問題がある。
【０００４】
そのため、図３に示すように、ＥＧＲ通路６の途中に水冷式のＥＧＲクーラー５を設けて、エンジン冷却水を冷却水通路７を通じて循環して、この冷却水によりＥＧＲガスＧｅを冷却して体積を減少してから、吸気マニホールド３に供給することによって、シリンダー内に供給される空気量を確保している。
しかしながら、エンジンの排気ガス中には、燃焼により生成される水分があるので、冬季やエンジンスタート直後のように、ＥＧＲクーラー５が冷えている時には、ＥＧＲクーラー５内でＥＧＲガス中の水蒸気が結露する。
【０００５】
このＥＧＲクーラー５内で発生した結露水に、ＥＧＲガス中のカーボンが捕捉されて、これが伝熱管などへ付着して伝熱抵抗層を形成して、ＥＧＲクーラー５の効率を低下させたり、さらに、ＥＧＲガス中の硫黄酸化物が結露水中に溶解して硫酸を生じて、ＥＧＲクーラー５、ＥＧＲ通路６およびエンジン１内部を腐蝕するという問題がある。
【０００６】
さらに、結露水が吸気行程で潤滑油中に溶けて潤滑油を酸化するので、潤滑性能が低下して各部の磨耗が促進されるという問題もある。
この問題を解決するために、本発明者は図４に示すように、新気の一部分Ａｂを希釈用分岐通路９を経由させてＥＧＲクーラー５の上流側に供給して水蒸気分の多いＥＧＲガスＧｅを希釈し、ＥＧＲクーラー５に供給されるＥＧＲガス（Ｇｅ＋Ａｂ）中の水蒸気濃度を低下させて露点温度を下げてＥＧＲクーラー５内での結露を防止する装置を開発した。
【０００７】
【発明が解決しようとする課題】
しかしながら、図４のような構成のＥＧＲ装置においては、過給器のコンプレッサ15によって吸気が昇圧されるので、希釈用分岐通路９を経由した新気の圧力Ｐ３は正圧であるが、ＥＧＲ通路６のＥＧＲクーラー５の入口付近のＥＧＲガスの圧力Ｐ５も、排気の圧力Ｐ２と略同じ大きさの正圧となる。
【０００８】
そして、吸気側の圧力Ｐ３の脈動が極めて小さいのに対して、排気側の圧力Ｐ５の脈動は比較的大きく、しかも、両者の平均的な圧力の差が小さい場合には、脈動する圧力Ｐ５の低くなった部分で、吸気側の圧力Ｐ３より低くなる場合が発生し、希釈用分岐通路９にＥＧＲガスが逆流することになる。この状態になると、新気をＥＧＲクーラー側へ常時供給してこのＥＧＲクーラー内を通過するＥＧＲガスを安定して希釈することができなくなる結果、ＥＧＲガス濃度が不均一となってエンジンの燃焼を不安定にするという問題がある。
【０００９】
前記逆流の問題を解決するために、図４の装置においては、ＥＧＲ通路６の入口部に逆止弁（リード弁）26を設けているが、この逆止弁26は高温の排気ガスに晒されるため傷み易く、また、カーボンも付着し易いので作動不良を起こし易いという問題がある。
本発明は、上述の問題を解決するためになされたもので、その目的は、ＥＧＲガスを新気で希釈して水蒸気濃度を低下させることにより、ＥＧＲクーラー内の結露を防止してＥＧＲクーラーの冷却効率の低下の防止や耐久性の向上を図る過給器付きエンジンのＥＧＲ装置において、新気に対してＥＧＲガスの圧力を積極的に低くすることによって、希釈用分岐通路を流れる新気を安定してＥＧＲ通路に供給してＥＧＲガスを希釈するようにして、エンジンの燃焼を良好に保ちながら、排気ガス中のＮＯｘの低減ができる装置を提供することにある。
【００１０】
【課題を解決するための手段】
以上のような目的を達成するためのＥＧＲクーラー付ＥＧＲ装置は、過給器付きエンジンのコンプレッサの吸気流通方向下流側の吸気通路と排気通路とを連結するＥＧＲ弁を有するＥＧＲ通路を設け、該ＥＧＲ通路と前記吸気通路の前記ＥＧＲ通路が合流する吸気流通方向上流側とを流量調整弁を有する希釈用分岐通路で連結すると共に、前記ＥＧＲ通路の前記希釈用分岐通路が接続するＥＧＲガス流通方向上流側にＥＧＲ弁を下流側にＥＧＲクーラーをそれぞれ設けて構成し、開閉制御される前記ＥＧＲ弁によって、前記希釈用分岐通路の前記ＥＧＲ通路との接続部の圧力Ｐ３を前記吸気通路の前記希釈用分岐通路との分岐部の圧力Ｐ１よりも低くするとともに、前記ＥＧＲ通路の前記希釈用分岐通路との接続部の圧力Ｐ５をこの接続部での前記希釈用分岐通路の圧力Ｐ３よりも低くするものであり、吸気分岐通路からの新気をＥＧＲ通路内に円滑に流入させることができる。
【００１１】
また、前記吸気通路の前記希釈用分岐通路が分岐する部分と前記ＥＧＲ通路が合流する部分との間に、吸気絞りを設け、開閉制御される該吸気絞りによって、前記吸気通路の前記ＥＧＲ通路との合流部の圧力Ｐ４を前記ＥＧＲ通路の前記希釈用分岐通路との接続部の圧力Ｐ５よりも低くすることにより、更に円滑に安定して希釈用分岐通路を経由した新気をＥＧＲクーラー側に供給することができてエンジンの燃焼状態を良好に保てる。
【００１２】
【発明の実施の形態】
図１に示すように、過給器付きエンジン１の排気マニホールドや排気管などの排気通路２と、コンプレッサ15の下流側の吸気通路８とを、ＥＧＲ通路６で接続し、このＥＧＲ通路６とこのＥＧＲ通路６が合流する合流部12の上流の吸気通路８とを新気Ａｂの量を調整する流量調節弁10を有する希釈用分岐通路９で連結し、前記ＥＧＲ通路６の希釈用分岐通路９が接続する接続部14より上流にＥＧＲガスＧｅの流量を調整するＥＧＲ弁４を設け、接続部14の下流にＥＧＲクーラー５を設けて構成する。
【００１３】
また、必要に応じて、過給器のコンプレッサで昇圧されて温度が上昇した新気を冷却するインタークーラー16を、吸気通路６の希釈用分岐通路９が分岐する分岐部13より上流側、あるいは下流側に設ける。
このような構成のＥＧＲ装置では、コンプレッサ15の下流側の吸気通路８に、希釈用分岐通路９の新気Ａｂの入口（分岐部13）を設けているので、この入口の吸気の圧力Ｐ１は、コンプレッサ15によって昇圧して比較的高い圧力となっており、その上、新気Ａｂの出口（接続部14）をＥＧＲ弁４の下流に設けているので、出口付近のＥＧＲガスの圧力Ｐ５をＥＧＲ弁４によって低下させることができ、流量調整弁10下流の新気の圧力Ｐ３よりも低くできる。
【００１４】
つまり、ＥＧＲ弁によって、ＥＧＲガスＧｅの流量調整と共に、Ｐ１＞Ｐ３＞Ｐ５になるように積極的に圧力差を形成できるので、希釈用分岐通路９の入口圧力Ｐ１より出口圧力Ｐ５を小さくして、この希釈用分岐通路９を流れる新気ＡｂをＥＧＲ通路６側に安定して供給することができる。その上、ＥＧＲガスＧｅの全量が必ずＥＧＲ弁４を通過する構成になっているので、ＥＧＲガスＧｅの流量を正確に調整できる。
【００１５】
次に、上記の構成に加えて、図２に示すように、希釈用分岐通路９が分岐する分岐部13とＥＧＲ通路６が合流する合流部12との間の吸気通路８に、絞り弁などの吸気絞り11を設けて構成する。
この吸気絞り11により、希釈されたＥＧＲガス（Ｇｅ＋Ａｂ）の出口（合流部12）の新気Ａｍの圧力Ｐ４を、ＥＧＲクーラー５の上流のＥＧＲガスの圧力Ｐ５より低下させて、Ｐ１＞Ｐ３＞Ｐ５＞Ｐ４とすることができるので、希釈用新気ＡｂとＥＧＲガスＧｅとをＥＧＲクーラー５に安定して流すことができる。
【００１６】
以上のように、安定して希釈用新気ＡｂでＥＧＲクーラー５を通過するＥＧＲガスＧｅを希釈できるので、安定したエンジンの燃焼を得られると共に、このＥＧＲガスの希釈による次のような効果を得ることができる。
希釈用新気Ａｂを水蒸気分の多いＥＧＲガスＧｅ中に混入して、ＥＧＲガス（Ｇｅ＋Ａｂ）中の水蒸気濃度を低下させて露点温度を下げることができるので、ＥＧＲクーラー５内の結露を防止できる。
【００１７】
従って、この結露水に排気ガス中の硫黄酸化物が溶解して発生する硫酸腐蝕も防止できるので、ＥＧＲクーラー５などの耐久性を向上でき、また、結露水が排気ガス中のカーボンを捕捉してＥＧＲクーラー５内の伝熱管にカーボンを付着させて伝熱抵抗層を形成するのを防止できるので、冷却効率の低下を防止できる。
特に、ディーゼルエンジンの場合には、燃料油の性状上、水分、硫黄分の含有がまぬがれず硫酸腐蝕及び燃焼時のカーボンの発生が多いのでより一層効果的となる。
【００１８】
また、希釈用分岐通路５に設けた流量調整弁10で希釈新気量Ａｂを結露しない最小限の量に調整できるので、ＥＧＲクーラー５を通過するガス量の増大とそれに伴う圧損増加を抑制できると共に、希釈されたＥＧＲガスの温度の低下を最小限に抑えて冷却水との温度差を比較的大きく保てるので、冷却効率の低下を少なくでき、ＥＧＲクーラー５が大型化するのを防止できる。
【００１９】
更に、低水温時や暖機後においても、低速低負荷運転時はＥＧＲガスＧｅを冷却すると、通常、ＮＯｘとスモークの低減よりもむしろ燃焼温度の低下によるＨＣ量の増加を招くが、本発明の構成によれば、流量調整弁10を制御することでバイパスの新気量Ａｂを増加することができるので、混合ガス（Ｇｅ＋Ａｂ）の温度を下げてＥＧＲクーラー５からの放熱量を抑制でき、燃焼温度の低下を防止してＨＣ量の増加を防ぐことができる。
【００２０】
【発明の効果】
本発明に係るＥＧＲクーラー付きＥＧＲ装置によれば、ＥＧＲ通路においてＥＧＲ弁を希釈用分岐通路の出口より上流に設けて、希釈用分岐通路の出口側のＥＧＲガスの圧力を積極的に低下できるように構成したので、希釈用分岐通路を経由してＥＧＲガスを希釈する新気を安定して供給することができる。
【００２１】
そして、更に、吸気通路において、希釈用分岐通路の分岐部とＥＧＲ通路の合流部との間に吸気絞りを設けたので、この吸気絞りによりＥＧＲクーラーの下流側の合流部と希釈用分岐通路の入口側の分岐部との圧力差を積極的に形成することができ、希釈用分岐通路へのＥＧＲガスの逆流を防止しながら希釈用新気でＥＧＲガスを更に安定して希釈することができる。
【００２２】
従って、結露による硫酸腐蝕やカーボン付着を防止することができると共に、エンジンの燃焼状態を安定して良好に保つことができる。
【図面の簡単な説明】
【図１】本発明の実施の形態を示すＥＧＲ装置の構成図である。
【図２】本発明の他の実施の形態を示すＥＧＲ装置の構成図である。
【図３】従来技術を示すＥＧＲ装置の構成図である。
【図４】改良前のＥＧＲ装置の構成図である。
【符号の説明】
１ … エンジン ２ … 排気通路
３ … 吸気マニホールド ４ … ＥＧＲ弁
５ … ＥＧＲクーラー ６ … ＥＧＲ通路
７ … 冷却水通路 ８ … 吸気通路
９ … 希釈用分岐通路 10 … 流量調節弁
11 … 吸気絞り 12 … 合流部
13 … 分岐部 14 … 接続部
15 … コンプレッサ
Ａｍ… 新気の主流部分 Ａｂ… 新気の一部分（希釈用）
Ｇ … 排気ガス Ｇｅ… ＥＧＲ用排気ガス[0001]
BACKGROUND OF THE INVENTION
In the EGR of the engine, the temperature of the EGR gas is lowered by the EGR cooler to improve the air intake efficiency to keep the engine combustion well, and the combustion temperature is lowered to reduce NOx in the exhaust gas. The present invention relates to an EGR device with an EGR cooler.
[0002]
[Prior art]
In exhaust gas countermeasures such as diesel engines, in order to reduce the amount of NOx emission in exhaust gas, EGR that suppresses the generation of NOx by reducing the combustion temperature low by recirculating a part of the exhaust gas to the intake air It is known that (exhaust gas recirculation) is effective, and is widely put into practical use.
[0003]
In this EGR device, an EGR passage that divides exhaust gas from the exhaust passage of the engine is connected to the intake passage side, and EGR is performed while the flow rate of EGR gas is adjusted by an EGR valve provided in the EGR passage.
However, if the high-temperature EGR gas is circulated to the intake side as it is, the EGR gas expanded at a high temperature is supplied to the intake manifold, and the ratio of the EGR gas in the cylinder during intake increases. There is a problem that the amount of air that enters is reduced.
[0004]
Therefore, as shown in FIG. 3, a water-cooled EGR cooler 5 is provided in the middle of the EGR passage 6, and engine cooling water is circulated through the cooling water passage 7 to cool the EGR gas Ge with this cooling water. Is reduced and then supplied to the intake manifold 3 to secure the amount of air supplied into the cylinder.
However, since there is moisture generated by combustion in the exhaust gas of the engine, water vapor in the EGR gas is condensed in the EGR cooler 5 when the EGR cooler 5 is cold, such as in winter or immediately after the engine starts. To do.
[0005]
Carbon in the EGR gas is captured by the dew condensation water generated in the EGR cooler 5, and this adheres to the heat transfer tube and the like to form a heat transfer resistance layer, thereby reducing the efficiency of the EGR cooler 5. There is a problem that the sulfur oxide in the EGR gas dissolves in the dew condensation water to produce sulfuric acid, which corrodes the EGR cooler 5, the EGR passage 6 and the engine 1 interior.
[0006]
Furthermore, since the condensed water dissolves in the lubricating oil during the intake stroke and oxidizes the lubricating oil, there is also a problem that the lubricating performance is lowered and wear of each part is promoted.
In order to solve this problem, as shown in FIG. 4, the present inventor supplies a part of fresh air Ab to the upstream side of the EGR cooler 5 via the diluting branch passage 9 to provide an EGR gas with a high water vapor content. A device was developed that dilutes Ge and lowers the dew point temperature by lowering the water vapor concentration in the EGR gas (Ge + Ab) supplied to the EGR cooler 5 to prevent condensation in the EGR cooler 5.
[0007]
[Problems to be solved by the invention]
However, in the EGR apparatus configured as shown in FIG. 4, the intake air is boosted by the compressor 15 of the supercharger, so the fresh air pressure P3 passing through the dilution branch passage 9 is positive, but the EGR passage The pressure P5 of the EGR gas in the vicinity of the inlet of the EGR cooler 5 is also a positive pressure substantially equal to the exhaust pressure P2.
[0008]
When the pulsation of the pressure P3 on the intake side is extremely small, the pulsation of the pressure P5 on the exhaust side is relatively large, and when the average pressure difference between the two is small, the pulsating pressure P5 In the lowered portion, a case where the pressure becomes lower than the pressure P3 on the intake side occurs, and the EGR gas flows back into the diluting branch passage 9. In this state, fresh air is constantly supplied to the EGR cooler side, and the EGR gas passing through the EGR cooler cannot be stably diluted. As a result, the EGR gas concentration becomes non-uniform and combustion of the engine occurs. There is a problem of making it unstable.
[0009]
In order to solve the problem of the backflow, in the apparatus shown in FIG. 4, a check valve (reed valve) 26 is provided at the inlet of the EGR passage 6, but this check valve 26 is exposed to high-temperature exhaust gas. Therefore, there is a problem that it is easily damaged and carbon is liable to adhere, so that malfunction is likely to occur.
The present invention has been made to solve the above-mentioned problems, and its purpose is to dilute the EGR gas with fresh air to reduce the water vapor concentration, thereby preventing condensation in the EGR cooler and In an EGR system for an engine with a supercharger that prevents a decrease in cooling efficiency and improves durability, the fresh air flowing through the dilution branch passage is reduced by actively lowering the pressure of the EGR gas relative to the fresh air. An object of the present invention is to provide an apparatus capable of reducing NOx in exhaust gas while maintaining good combustion of the engine by stably supplying the EGR passage to dilute the EGR gas.
[0010]
[Means for Solving the Problems]
An EGR device with an EGR cooler for achieving the above object is provided with an EGR passage having an EGR valve for connecting an intake passage and an exhaust passage on the downstream side in the intake air flow direction of a compressor of an engine with a supercharger, An EGR gas flow direction in which the EGR passage and the upstream side in the intake flow direction where the EGR passage of the intake passage joins are connected by a diluting branch passage having a flow rate adjusting valve, and the diluting branch passage of the EGR passage is connected An EGR valve is provided on the upstream side, and an EGR cooler is provided on the downstream side. By the EGR valve that is controlled to open and close, the pressure P3 of the connection portion of the dilution branch passage with the EGR passage is changed to the dilution of the intake passage. The pressure P5 of the connecting portion of the EGR passage with the diluting branch passage is made lower than the pressure P1 of the branching portion with the branch passage for use at this connection portion. Wherein is intended to be lower than the pressure P3 of the diluent branch passage, it is possible to smoothly flow into the fresh air from the intake branch passage in the EGR passage.
[0011]
In addition, an intake throttle is provided between a portion where the diluting branch passage of the intake passage branches and a portion where the EGR passage joins, and the intake throttle that is controlled to be opened and closed is used to connect the EGR passage of the intake passage to the EGR passage. By making the pressure P4 at the junction of the EGR passage lower than the pressure P5 at the connection portion of the EGR passage with the dilution branch passage, the fresh air passing through the dilution branch passage is more smoothly and stably sent to the EGR cooler side. It can be supplied and the combustion state of the engine can be kept good.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, an exhaust passage 2 such as an exhaust manifold or an exhaust pipe of an engine 1 with a supercharger and an intake passage 8 on the downstream side of the compressor 15 are connected by an EGR passage 6, and the EGR passage 6 A dilution branch passage 9 having a flow rate adjusting valve 10 for adjusting the amount of fresh air Ab is connected to the intake passage 8 upstream of the junction 12 where the EGR passage 6 joins, and the dilution branch passage of the EGR passage 6 is connected. An EGR valve 4 that adjusts the flow rate of the EGR gas Ge is provided upstream of the connection portion 14 to which 9 is connected, and an EGR cooler 5 is provided downstream of the connection portion 14.
[0013]
Further, if necessary, an intercooler 16 that cools fresh air that has been pressurized by a turbocharger compressor and that has risen in temperature is connected to an upstream side or a downstream side of a branching section 13 where a dilution branching passage 9 of the intake passage 6 branches. Provide on the side.
In the EGR device having such a configuration, the intake air passage 8 on the downstream side of the compressor 15 is provided with the inlet (branch portion 13) of the fresh air Ab of the dilution branch passage 9, so that the intake pressure P1 at this inlet is Further, the pressure is increased by the compressor 15 to a relatively high pressure, and the outlet (connecting portion 14) of the fresh air Ab is provided downstream of the EGR valve 4. Therefore, the pressure P5 of the EGR gas in the vicinity of the outlet is increased. The pressure can be lowered by the EGR valve 4 and can be lower than the pressure P3 of fresh air downstream of the flow rate adjusting valve 10.
[0014]
That is, the EGR valve can positively form a pressure difference so that P1>P3> P5 as well as adjusting the flow rate of the EGR gas Ge, so that the outlet pressure P5 is made smaller than the inlet pressure P1 of the dilution branch passage 9. The fresh air Ab flowing through the diluting branch passage 9 can be stably supplied to the EGR passage 6 side. In addition, since the total amount of the EGR gas Ge always passes through the EGR valve 4, the flow rate of the EGR gas Ge can be adjusted accurately.
[0015]
Next, in addition to the above configuration, as shown in FIG. 2, a throttle valve or the like is provided in the intake passage 8 between the branch portion 13 where the diluting branch passage 9 branches and the junction portion 12 where the EGR passage 6 joins. The intake throttle 11 is provided.
The intake air throttle 11 lowers the pressure P4 of fresh air Am at the outlet (merging portion 12) of the diluted EGR gas (Ge + Ab) below the pressure P5 of the EGR gas upstream of the EGR cooler 5, and P1>P3> Since P5> P4, the dilution fresh air Ab and the EGR gas Ge can be stably flowed to the EGR cooler 5.
[0016]
As described above, the EGR gas Ge passing through the EGR cooler 5 can be stably diluted with the fresh air Ab for dilution, so that stable engine combustion can be obtained and the following effects can be obtained by dilution of the EGR gas. Obtainable.
Since the fresh air Ab for dilution is mixed in the EGR gas Ge having a high water vapor content, the dew point temperature can be lowered by lowering the water vapor concentration in the EGR gas (Ge + Ab), so that dew condensation in the EGR cooler 5 can be prevented. .
[0017]
Accordingly, since sulfuric acid corrosion caused by dissolution of sulfur oxides in the exhaust gas in the condensed water can be prevented, the durability of the EGR cooler 5 and the like can be improved, and the condensed water captures the carbon in the exhaust gas. Thus, it is possible to prevent carbon from adhering to the heat transfer tube in the EGR cooler 5 to form a heat transfer resistance layer, thereby preventing a decrease in cooling efficiency.
In particular, in the case of a diesel engine, the moisture and sulfur content is not completely removed due to the properties of the fuel oil, so that sulfuric acid corrosion and generation of carbon during combustion are much more effective.
[0018]
Further, since the diluted fresh air amount Ab can be adjusted to a minimum amount that does not condense by the flow rate adjusting valve 10 provided in the diluting branch passage 5, an increase in the amount of gas passing through the EGR cooler 5 and an accompanying increase in pressure loss can be suppressed. At the same time, since the temperature difference from the cooling water can be kept relatively large by minimizing the decrease in the temperature of the diluted EGR gas, the decrease in cooling efficiency can be reduced, and the EGR cooler 5 can be prevented from being enlarged.
[0019]
Furthermore, even when the water temperature is low or after warming up, cooling the EGR gas Ge during low-speed and low-load operation usually causes an increase in the amount of HC due to a decrease in combustion temperature rather than a reduction in NOx and smoke. According to the configuration, since the bypass fresh air amount Ab can be increased by controlling the flow rate adjustment valve 10, the temperature of the mixed gas (Ge + Ab) can be lowered to suppress the amount of heat released from the EGR cooler 5, It is possible to prevent an increase in the amount of HC by preventing a decrease in the combustion temperature.
[0020]
【The invention's effect】
According to the EGR apparatus with an EGR cooler according to the present invention, an EGR valve is provided upstream of the outlet of the diluting branch passage in the EGR passage so that the pressure of the EGR gas on the outlet side of the diluting branch passage can be actively reduced. Thus, fresh air for diluting the EGR gas can be stably supplied via the dilution branch passage.
[0021]
Further, since the intake throttle is provided between the branch portion of the dilution branch passage and the merge portion of the EGR passage in the intake passage, the intake throttle restricts the merge portion on the downstream side of the EGR cooler and the dilution branch passage. A pressure difference with the branch portion on the inlet side can be positively formed, and the EGR gas can be diluted more stably with the fresh air for dilution while preventing the backflow of the EGR gas to the dilution branch passage. .
[0022]
Therefore, sulfuric acid corrosion and carbon adhesion due to condensation can be prevented, and the combustion state of the engine can be kept stable and good.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an EGR apparatus showing an embodiment of the present invention.
FIG. 2 is a configuration diagram of an EGR apparatus showing another embodiment of the present invention.
FIG. 3 is a configuration diagram of an EGR apparatus showing a conventional technique.
FIG. 4 is a configuration diagram of an EGR device before improvement.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Exhaust passage 3 ... Intake manifold 4 ... EGR valve 5 ... EGR cooler 6 ... EGR passage 7 ... Cooling water passage 8 ... Intake passage 9 ... Dilution branch passage 10 ... Flow control valve
11… intake throttle 12… confluence
13… Branch 14… Connection
15 ... Compressor Am ... Mainstream part of fresh air Ab ... Part of fresh air (for dilution)
G ... exhaust gas Ge ... exhaust gas for EGR

Claims (2)

過給器付きエンジンのコンプレッサの吸気流通方向下流側の吸気通路と排気通路とを連結するＥＧＲ弁を有するＥＧＲ通路を設け、該ＥＧＲ通路と前記吸気通路の前記ＥＧＲ通路が合流する吸気流通方向上流側とを流量調整弁を有する希釈用分岐通路で連結すると共に、前記ＥＧＲ通路の前記希釈用分岐通路が接続するＥＧＲガス流通方向上流側にＥＧＲ弁を下流側にＥＧＲクーラーをそれぞれ設けて構成し、開閉制御される前記ＥＧＲ弁によって、前記希釈用分岐通路の前記ＥＧＲ通路との接続部の圧力Ｐ３を前記吸気通路の前記希釈用分岐通路との分岐部の圧力Ｐ１よりも低くするとともに、前記ＥＧＲ通路の前記希釈用分岐通路との接続部の圧力Ｐ５をこの接続部での前記希釈用分岐通路の圧力Ｐ３よりも低くするＥＧＲクーラー付きＥＧＲ装置。An EGR passage having an EGR valve that connects an intake passage and an exhaust passage on the downstream side of the intake air circulation direction of the compressor of the supercharged engine is provided, and the EGR passage and the intake passage upstream of the intake air passage where the EGR passage merges The EGR valve is connected to the EGR gas flow direction upstream side of the EGR passage, and the EGR cooler is provided downstream of the EGR passage. The EGR valve that is controlled to open and close causes the pressure P3 at the connection portion of the dilution branch passage to the EGR passage to be lower than the pressure P1 at the branch portion of the intake passage from the dilution branch passage, and wherein with EGR cooler to be lower than the pressure P3 of the diluent branch passage in the connecting part the pressure P5 of the connecting portion between the dilution branch passage of the EGR passage GR apparatus. 前記吸気通路の前記希釈用分岐通路が分岐する部分と前記ＥＧＲ通路が合流する部分との間に、吸気絞りを設け、開閉制御される該吸気絞りによって、前記吸気通路の前記ＥＧＲ通路との合流部の圧力Ｐ４を前記ＥＧＲ通路の前記希釈用分岐通路との接続部の圧力Ｐ５よりも低くする請求項１記載のＥＧＲクーラー付きＥＧＲ装置。An intake throttle is provided between a portion where the diluting branch passage of the intake passage branches and a portion where the EGR passage joins, and the intake throttle that is controlled to open and close joins the intake passage with the EGR passage. The EGR device with an EGR cooler according to claim 1 , wherein the pressure P4 of the section is lower than the pressure P5 of the connection portion of the EGR passage with the diluting branch passage .
JP01523497A 1997-01-29 1997-01-29 EGR equipment with EGR cooler Expired - Fee Related JP3695038B2 (en)

Priority Applications (1)

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JP01523497A JP3695038B2 (en) 1997-01-29 1997-01-29 EGR equipment with EGR cooler

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Application Number Priority Date Filing Date Title
JP01523497A JP3695038B2 (en) 1997-01-29 1997-01-29 EGR equipment with EGR cooler

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JPH10213020A JPH10213020A (en) 1998-08-11
JP3695038B2 true JP3695038B2 (en) 2005-09-14

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Publication number Priority date Publication date Assignee Title
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
JP5573701B2 (en) * 2011-01-24 2014-08-20 トヨタ自動車株式会社 Internal combustion engine
KR101816429B1 (en) * 2016-08-10 2018-01-08 현대자동차주식회사 Method for Removing EGR Impurity by using Air Blowing, Exhaust Gas Recirculation System and Vehicle thereof
CN113958417B (en) * 2021-10-21 2024-01-23 中国重汽集团济南动力有限公司 High-temperature protection control method and device for EGR check valve and storage medium

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