JP2004019589A - Exhaust gas recirculation equipment for supercharging diesel engine - Google Patents

Exhaust gas recirculation equipment for supercharging diesel engine Download PDF

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Publication number
JP2004019589A
JP2004019589A JP2002177455A JP2002177455A JP2004019589A JP 2004019589 A JP2004019589 A JP 2004019589A JP 2002177455 A JP2002177455 A JP 2002177455A JP 2002177455 A JP2002177455 A JP 2002177455A JP 2004019589 A JP2004019589 A JP 2004019589A
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Prior art keywords
diesel engine
passage
exhaust gas
air supply
exhaust
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JP2002177455A
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Japanese (ja)
Inventor
Nobuyuki Iketani
池谷　信之
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IHI Corp
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IHI Corp
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Priority to JP2002177455A priority Critical patent/JP2004019589A/en
Publication of JP2004019589A publication Critical patent/JP2004019589A/en
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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
    • F02M26/02—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
    • 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
    • F02B29/00—Engines characterised by provision for charging or scavenging not provided for in groups F02B25/00, F02B27/00 or F02B33/00 - F02B39/00; Details thereof
    • F02B29/04—Cooling of air intake supply
    • F02B29/0406—Layout of the intake air cooling or coolant circuit
    • 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
    • F02M26/22—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with coolers in the recirculation passage
    • F02M26/23—Layout, e.g. schematics

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

Abstract

<P>PROBLEM TO BE SOLVED: To increase the amount of exhaust gas recirculation while maintaining an excess air ratio during the operation of a supercharging diesel engine at in low revolution speed region. <P>SOLUTION: An outlet of a compressor 3 of a supercharger 1 is connected to an air supply passage 8 of the diesel engine 4, and an exhaust passage 7 of the diesel engine 4 is connected to an inlet of a turbine 2 of the supercharger 1. A circulation passage 11 for recirculating exhaust gas 9 is connected to the exhaust side and the intake side of the diesel engine 4. An air supply bypass passage 16 is connected to the intake side and the exhaust side of the diesel engine 4. The air supply bypass passage bypasses part of compressed air 10 to the exhaust side to thereby raise pressure on the exhaust side during the operation of the diesel engine 4 in the low revolution speed region. The air supply bypass passage 16 is connected at a position further adjacent to the compressor 3 and the turbine 2 than the circulation passage 11. A check valve 17 is provided in the middle of the air supply bypass passage 16 so as to prevent the counterflow of the exhaust gas 9. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明はディーゼルエンジンから排出される排気ガスの一部を再循環して使用する際に空気過剰率を保ったまま再循環量を増加させることができるようにした過給ディーゼルエンジンの排気ガス再循環装置に関するものである。
【０００２】
【従来の技術】
大型のトラックやバス等に搭載されているディーゼルエンジンの排気ガスを浄化させる方式の一つとして、排気ガス再循環（ＥＧＲ）方式がある。かかるＥＧＲ方式は、図２にその一例の概略を示す如く、タービン２と圧縮機３とをタービン軸２ａで連結してなる過給機１を、ディーゼルエンジン４の排気マニホールド５及び給気マニホールド６に、タービン入口通路となる排気通路７及び圧縮機出口通路となる給気通路８を介して接続し、ディーゼルエンジン４からの排気ガス９を、排気通路７を通してタービン２に送り、該排気ガス９によるタービン２の駆動により圧縮機３を作動させて、圧縮空気１０を給気通路８を通してディーゼルエンジン４に給気するようにしてある構成において、上記ディーゼルエンジン４の排気通路７と給気通路８との間に、循環通路（ＥＧＲ通路）１１を設け、且つ該循環通路１１の途中に調節弁（ＥＧＲ弁）１２を設けた構成として、排気通路７を通る排気ガス９の一部を、給気側との圧力差に基づいて循環通路１１より給気通路８に送り、給気通路８を通る圧縮空気１０に混入させてディーゼルエンジン４に循環供給できるようにし、これにより、燃焼混合気中の不活性ガスの割合を増加させて、酸素濃度を低下させると共に燃焼温度を下げてＮＯｘの発生を抑えることができるようにしてある。なお、１３は圧縮空気１０を必要に応じて冷却するインタークーラー、１４は再循環させる排気ガス９を必要に応じて冷却するＥＧＲクーラーを示す。
【０００３】
ところで、トラック等で用いられている大型のディーゼルエンジン４では、しばしば低速のトルクが要求されるが、そのためには高い過給圧が必要となる。このような大型のディーゼルエンジン４の低回転数領域での運転時にＥＧＲを実施するために、最近では、タービン２として、可変容量型タービンを用い、タービン流量を小容量とすることによってタービン２の入口圧力を上昇させるようにすることが行われている。すなわち、タービン流量を小容量とすることにより給気側と排気側の圧力の差を増大させ、結果として圧縮機作動線をサージ側へ移動させ、効率低下によりバランスさせている。
【０００４】
【発明が解決しようとする課題】
ところが、上記のように、ＥＧＲ量を増加させようとタービン２の容量を小容量へ変化させると、次第にディーゼルエンジン４の空気過剰率が低下して煙が排出され易くなるため、エンジン出力を制限したりする必要が生じてしまう。又、過給ディーゼルエンジン４の低回転数領域では、エンジン排気の脈動が大きいため、循環通路１１内を給気側の圧縮空気１０と排気側の排気ガス９とが行き来しながら排気ガス９が給気通路８に流入することになり、その結果、ＥＧＲ量を増やすことはできずにＮＯｘが多く排出され易くなってしまう。
【０００５】
したがって、過給ディーゼルエンジンの低回転数領域での運転時においても、排気ガス規制強化に対応するために、より多くのＥＧＲを行いたいが、空気過剰率を高く保ったまま高ＥＧＲを達成することは、現時点では困難である。
【０００６】
そこで、本発明は、過給ディーゼルエンジンの低回転数領域での運転時でも、空気過剰率を保ったままＥＧＲ量を増加させることができるようにしようとするものである。
【０００７】
【課題を解決するための手段】
本発明は、上記課題を解決するために、ディーゼルエンジンの給気通路に過給機の圧縮機出口を接続すると共に、ディーゼルエンジンの排気通路を過給機のタービン入口に接続し、上記ディーゼルエンジンの排気ガスの一部を循環通路を通し給気側に戻して再循環させるようにしてある過給ディーゼルエンジンの排気ガス再循環装置において、上記ディーゼルエンジンの排気側と給気側との間に、給気側の圧縮空気の一部を排気側へ流すようにする給気バイパス通路を接続して設けた構成とする。
【０００８】
ディーゼルエンジンの低回転数領域での運転時において、給気側の圧縮空気の一部を給気バイパス通路を通して排気側へ流すようにすると、排気通路の圧力が上昇するので、空気過剰率を保ったままＥＧＲ量を増やすことができる。
【０００９】
又、給気バイパス通路に逆止弁を設けた構成とすることにより、給気バイパス通路を通っての排気ガスの逆流を確実に防ぐことができる。
【００１０】
更に、給気バイパス通路の逆止弁よりも下流位置に流量調整弁を設けた構成とすることにより、流量調整弁の開度を調整することで、圧縮空気の排気側への流れ過ぎを防ぐことができる。
【００１１】
更に又、給気バイパス通路の接続位置をタービン入口及び圧縮機出口に近い位置とし、循環通路の位置をディーゼルエンジンに近い位置とした構成とすることにより、濃い排気ガスを効率よく給気通路へ流してディーゼルエンジンに過給することができるようになるので、ＮＯｘをより低減できることになる。
【００１２】
【発明の実施の形態】
以下、本発明の実施の形態を図面を参照して説明する。
【００１３】
図１は本発明の実施の一形態を示すもので、図２に示したと同様に、タービン２と圧縮機３とからなる過給機１を、タービン入口通路となる排気通路７と圧縮機出口通路となる給気通路８を介してディーゼルエンジン４の排気マニホールド５と給気マニホールド６に接続し、ディーゼルエンジン４の排気ガス９の一部を、循環通路１１を通すことにより給気側に戻して再循環させるようにしてある過給ディーゼルエンジンの排気ガス再循環装置において、上記給気通路８の圧縮機出口部と排気通路７のタービン入口部（又は排気マニホールド５）との間に給気バイパス通路１６を接続して設けて、上記循環通路１１を、該給気バイパス通路１６の接続位置よりもタービン２及び圧縮機３から離れた遠い位置として、排気マニホールド５と給気マニホールド６との間に接続し、ディーゼルエンジン４の低回転数領域での運転時に、圧縮機３から給気通路８へ吐出された圧縮機出口部の圧縮空気１０の一部を、上記給気バイパス通路１６を通して排気通路７に送り、排気通路７を通る排気ガス９に混入させることにより、排気側の圧力が高められるようにする。
【００１４】
又、上記給気バイパス通路１６の途中に、圧縮空気１０が排気側へのみ流れるように逆止弁１７を設けて、給気バイパス通路１６を通しての排気通路７から給気通路８への排気ガス９の逆流を防止できるようにし、且つ上記給気バイパス通路１６の逆止弁１７よりも下流位置に、流量調整弁１８を設けて、該流量調整弁１８の開度調整により、ディーゼルエンジン４の低回転数領域での運転時に、給気側から排出側へ流れる圧縮空気１０の流量を適正に調整できるようにする。
【００１５】
その他の構成は図２に示したものと同様であり、図２と同一部分には同一符号が付してある。
【００１６】
ディーゼルエンジン４の低回転数領域（たとえば、８００ｒｐｍ）での運転時には、排気側に高回転より大きな脈動があり、定期的に給気側よりも排気側の圧力が低くなるときがあるので、このようなときには、圧縮機３から給気通路８に吐出された圧縮機出口部の圧縮空気１０の一部が給気バイパス通路１６を通って排気通路７に流入することになる。なお、給気バイパス通路１６には逆止弁１７が設けてあるため、排気側に脈動があって、排気側の圧力が給気側の圧力よりも高くなる時期でも、排気ガス９が給気バイパス通路１６を通って給気通路８に逆流することはなく、したがって、安定した運転を行うことができる。このようにして、圧縮空気１０の一部が排気通路７に流入すると、排気通路７の圧力、すなわち、ディーゼルエンジン４の排気マニホールド５側の圧力が上昇するので、循環通路１１を通してのＥＧＲが掛け易くなり、空気過剰率を保ったままＥＧＲ量を増加させることができる。この場合において、循環通路１１は給気バイパス通路１６よりもディーゼルエンジン４に近い位置にあるので、圧縮空気１０が混入する前の濃い排気ガス９を再循環させることができる。したがって、ＮＯｘを減少させ且つ出力も向上できることになり、更に、燃料消費率の悪化も抑制することができるようになる。
【００１７】
上記において、給気バイパス通路１６には、逆止弁１７の下流位置に流量調整弁１８が設けてあるため、該流量調整弁１８の開度を適正に選定しておくことにより、圧縮空気１０の排気側への流れ過ぎを防ぐことができ、又、ディーゼルエンジン４の中、高速回転領域での運転時には、上記流量調整弁１８を閉じておくことによって、排気側に脈動が発生するような事態が発生したとしても、あるいは、逆止弁１７の機能が低下するような事態が発生したとしても、給気側から排気側への圧縮空気１０の流入を確実に防止することができて、安定した運転を行うことができる。又、上述したように、ディーゼルエンジン４の低回転数領域時に、給気をバイパスさせると、タービン流量を増やすことができるので、低速域の圧縮機流量を増やして駆動力を大きくすることができ、これにより、圧縮機レンジの実質作動レンジが縮小するので、圧縮機３の設計が容易になるという利点があり、これに伴い、タービン２の効率が高い領域を使えるようになるので有利である。
【００１８】
なお、上記実施の形態では、便宜上、ディーゼルエンジン４の排気マニホールド５と排気通路７とを別のものとして説明したが、排気通路７は排気マニホールド５の一部を構成するものであること、更に、本発明で採用するタービン２としては、可変容量型であってもよく、又、可変容量型でなくてもよいこと、その他本発明の要旨を逸脱しない範囲内において、種々変更を加え得ることは勿論である。
【００１９】
【発明の効果】
以上述べた如く、本発明の過給ディーゼルエンジンの排気ガス再循環装置によれば、次の如き優れた効果を発揮する。
（１）ディーゼルエンジンの給気通路に過給機の圧縮機出口を接続すると共に、ディーゼルエンジンの排気通路を過給機のタービン入口に接続し、上記ディーゼルエンジンの排気ガスの一部を循環通路を通し給気側に戻して再循環させるようにしてある過給ディーゼルエンジンの排気ガス再循環装置において、上記ディーゼルエンジンの排気側と給気側との間に、給気側の圧縮空気の一部を排気側へ流すようにする給気バイパス通路を接続して設けた構成としてあるので、ディーゼルエンジンの低回転数領域での運転時に、給気側の圧縮空気の一部を給気バイパス通路を通して排気側に流すことにより、排気側の圧力を高めることができ、これにより空気過剰率を保ったままＥＧＲ量を増加させることができ、出力も向上させることができる。
（２）給気バイパス通路に逆止弁を設けた構成とすることにより、給気バイパス通路を通しての排気側から給気側への排気ガスの逆流を確実に防ぐことができる。
（３）給気バイパス通路の逆止弁よりも下流位置に流量調整弁を設けた構成とすることにより、流量調整弁の開度を適正に選定することで、圧縮空気の排気側への流れ過ぎを防ぐことができて、安定した運転を行うことができる。
（４）給気バイパス通路の接続位置をタービン入口及び圧縮機出口に近い位置とし、循環通路の位置をディーゼルエンジンに近い位置とした構成とすることにより、濃い排気ガスを効率よく給気通路に流入させてディーゼルエンジンに過給することができるので、ＮＯｘをより低減させることができる。
【図面の簡単な説明】
【図１】本発明の過給ディーゼルエンジンの排気ガス再循環装置の実施の一形態を示す概略図である。
【図２】排気ガス再循環方式を採用した従来の過給ディーゼルエンジンの一例を示す概略図である。
【符号の説明】
１　過給機
２　タービン
３　圧縮機
４　ディーゼルエンジン
７　排気通路
８　給気通路
９　排気ガス
１０　圧縮空気
１１　循環通路
１６　給気バイパス通路
１７　逆止弁
１８　流量調整弁[0001]
TECHNICAL FIELD OF THE INVENTION
SUMMARY OF THE INVENTION The present invention provides an exhaust gas recirculation system for a supercharged diesel engine in which a part of exhaust gas discharged from a diesel engine can be recirculated for use while increasing the amount of recirculation while maintaining an excess air ratio. The present invention relates to a circulation device.
[0002]
[Prior art]
An exhaust gas recirculation (EGR) method is one of the methods for purifying exhaust gas of a diesel engine mounted on a large truck or a bus. As shown schematically in FIG. 2, one example of such an EGR system is that a supercharger 1 having a turbine 2 and a compressor 3 connected by a turbine shaft 2a is connected to an exhaust manifold 5 and a supply manifold 6 of a diesel engine 4. Through an exhaust passage 7 serving as a turbine inlet passage and an air supply passage 8 serving as a compressor outlet passage, and sends exhaust gas 9 from the diesel engine 4 to the turbine 2 through the exhaust passage 7. The compressor 3 is operated by the drive of the turbine 2 to supply the compressed air 10 to the diesel engine 4 through the air supply passage 8 in the exhaust passage 7 and the air supply passage 8 of the diesel engine 4. A circulation passage (EGR passage) 11 is provided between the exhaust passage 7 and a control valve (EGR valve) 12 provided in the middle of the circulation passage 11. A part of the exhaust gas 9 is sent from the circulation passage 11 to the air supply passage 8 based on the pressure difference from the air supply side, mixed with the compressed air 10 passing through the air supply passage 8, and can be circulated and supplied to the diesel engine 4. Thus, the ratio of the inert gas in the combustion mixture is increased to lower the oxygen concentration and lower the combustion temperature to suppress the generation of NOx. Reference numeral 13 denotes an intercooler for cooling the compressed air 10 as needed, and reference numeral 14 denotes an EGR cooler for cooling the recirculated exhaust gas 9 as needed.
[0003]
By the way, large diesel engines 4 used in trucks and the like often require low-speed torque, but for that purpose, high supercharging pressure is required. In order to perform EGR during operation of such a large diesel engine 4 in a low rotation speed range, recently, a variable displacement turbine is used as the turbine 2 and the turbine flow rate is reduced to reduce the turbine flow. Attempts have been made to increase the inlet pressure. That is, by reducing the turbine flow rate, the difference between the pressure on the supply side and the pressure on the exhaust side is increased, and as a result, the compressor operation line is moved to the surge side, and the efficiency is reduced to balance.
[0004]
[Problems to be solved by the invention]
However, as described above, when the capacity of the turbine 2 is changed to a small capacity in order to increase the EGR amount, the excess air ratio of the diesel engine 4 gradually decreases and smoke is easily emitted, so that the engine output is limited. Or the need to do so. Further, in the low rotation speed region of the supercharged diesel engine 4, the pulsation of the engine exhaust gas is large, so that the exhaust gas 9 flows while the compressed air 10 on the intake side and the exhaust gas 9 on the exhaust side flow in the circulation passage 11. As a result, the EGR amount cannot be increased and a large amount of NOx is likely to be discharged.
[0005]
Therefore, even during operation of the supercharged diesel engine in the low rotation speed region, it is desired to perform more EGR to cope with the stricter exhaust gas regulations, but achieve high EGR while maintaining the excess air ratio high. That is difficult at the moment.
[0006]
Therefore, the present invention is intended to increase the EGR amount while maintaining the excess air ratio even during the operation of the supercharged diesel engine in the low rotation speed region.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention connects the compressor outlet of a supercharger to a supply passage of a diesel engine, and connects an exhaust passage of a diesel engine to a turbine inlet of a supercharger. A part of the exhaust gas of the supercharged diesel engine is returned to the air supply side through the circulation passage and recirculated, in the exhaust gas recirculation device of the supercharged diesel engine, between the exhaust side and the air supply side of the diesel engine In addition, a configuration is provided in which an air supply bypass passage for connecting a part of the compressed air on the air supply side to the exhaust side is connected.
[0008]
During operation of the diesel engine in the low rotation speed region, if a part of the compressed air on the air supply side is caused to flow to the exhaust side through the air supply bypass passage, the pressure in the exhaust passage increases, so that the excess air ratio is maintained. It is possible to increase the EGR amount while maintaining.
[0009]
Further, by providing the check valve in the air supply bypass passage, it is possible to reliably prevent the exhaust gas from flowing back through the air supply bypass passage.
[0010]
Further, by providing a flow control valve at a position downstream of the check valve in the air supply bypass passage, the opening of the flow control valve is adjusted to prevent excessive flow of compressed air to the exhaust side. be able to.
[0011]
Furthermore, by making the connection position of the air supply bypass passage close to the turbine inlet and the compressor outlet and the circulation passage close to the diesel engine, rich exhaust gas can be efficiently supplied to the air supply passage. Since it becomes possible to flow and supercharge the diesel engine, NOx can be further reduced.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 shows an embodiment of the present invention. As shown in FIG. 2, a supercharger 1 including a turbine 2 and a compressor 3 is replaced with an exhaust passage 7 serving as a turbine inlet passage and a compressor outlet. It is connected to the exhaust manifold 5 and the supply manifold 6 of the diesel engine 4 through the supply passage 8 serving as a passage, and a part of the exhaust gas 9 of the diesel engine 4 is returned to the supply side by passing through the circulation passage 11. In the exhaust gas recirculation system for a supercharged diesel engine, which is configured to recirculate the exhaust gas, the air supply between the compressor outlet of the air supply passage 8 and the turbine inlet (or the exhaust manifold 5) of the exhaust passage 7 is performed. A bypass passage 16 is connected and provided, and the circulation passage 11 is located farther from the turbine 2 and the compressor 3 than the connection position of the air supply bypass passage 16, and the exhaust manifold 5 and the air supply And a portion of the compressed air 10 discharged from the compressor 3 to the air supply passage 8 at the compressor outlet when the diesel engine 4 is operated in the low rotation speed region. The gas is sent to the exhaust passage 7 through the bypass passage 16 and mixed with the exhaust gas 9 passing through the exhaust passage 7 so that the pressure on the exhaust side is increased.
[0014]
Also, a check valve 17 is provided in the supply air bypass passage 16 so that the compressed air 10 flows only to the exhaust side, and the exhaust gas from the exhaust passage 7 through the air supply bypass passage 16 to the air supply passage 8 is provided. 9 can be prevented, and a flow rate control valve 18 is provided at a position downstream of the check valve 17 in the air supply bypass passage 16. During operation in the low rotation speed region, the flow rate of the compressed air 10 flowing from the supply side to the discharge side can be appropriately adjusted.
[0015]
Other configurations are the same as those shown in FIG. 2, and the same parts as those in FIG. 2 are denoted by the same reference numerals.
[0016]
During operation of the diesel engine 4 in a low rotation speed region (for example, 800 rpm), there is a pulsation larger than the high rotation speed on the exhaust side, and the pressure on the exhaust side may be periodically lower than that on the supply side. In such a case, part of the compressed air 10 at the compressor outlet discharged from the compressor 3 to the air supply passage 8 flows into the exhaust passage 7 through the air supply bypass passage 16. Since the check valve 17 is provided in the air supply bypass passage 16, the exhaust gas 9 is supplied even when there is pulsation on the exhaust side and the pressure on the exhaust side becomes higher than the pressure on the air supply side. There is no backflow to the air supply passage 8 through the bypass passage 16, so that stable operation can be performed. In this way, when a part of the compressed air 10 flows into the exhaust passage 7, the pressure in the exhaust passage 7, that is, the pressure on the exhaust manifold 5 side of the diesel engine 4 increases, so that the EGR through the circulation passage 11 is applied. This makes it easier to increase the EGR amount while maintaining the excess air ratio. In this case, since the circulation passage 11 is located closer to the diesel engine 4 than the air supply bypass passage 16, the rich exhaust gas 9 before the compressed air 10 is mixed can be recirculated. Therefore, NOx can be reduced and the output can be improved, and further, the deterioration of the fuel consumption rate can be suppressed.
[0017]
In the above description, since the flow regulating valve 18 is provided in the air supply bypass passage 16 at a position downstream of the check valve 17, by appropriately selecting the opening degree of the flow regulating valve 18, the compressed air 10 Can be prevented from flowing excessively to the exhaust side, and when the diesel engine 4 is operating in a high-speed rotation region, the pulsation may be generated on the exhaust side by closing the flow control valve 18. Even if a situation occurs, or even if a situation occurs in which the function of the check valve 17 is reduced, it is possible to reliably prevent the compressed air 10 from flowing from the supply side to the exhaust side, Stable operation can be performed. Further, as described above, when the air supply is bypassed in the low rotation speed region of the diesel engine 4, the turbine flow rate can be increased, so that the compressor flow rate in the low speed range can be increased to increase the driving force. Thereby, since the substantial operating range of the compressor range is reduced, there is an advantage that the design of the compressor 3 is facilitated, and accordingly, an area where the efficiency of the turbine 2 is high can be advantageously used. .
[0018]
In the above embodiment, for convenience, the exhaust manifold 5 of the diesel engine 4 and the exhaust passage 7 have been described as being different from each other, but the exhaust passage 7 constitutes a part of the exhaust manifold 5, and The turbine 2 employed in the present invention may be of a variable capacity type, may not be of a variable capacity type, and may be variously modified without departing from the gist of the present invention. Of course.
[0019]
【The invention's effect】
As described above, according to the exhaust gas recirculation system for a supercharged diesel engine of the present invention, the following excellent effects are exhibited.
(1) The compressor outlet of the supercharger is connected to the supply passage of the diesel engine, the exhaust passage of the diesel engine is connected to the turbine inlet of the supercharger, and a part of the exhaust gas of the diesel engine is circulated to the circulation passage. In the exhaust gas recirculation system for a supercharged diesel engine, which is returned to the air supply side through the air passage and recirculated, one of the compressed air on the air supply side is provided between the exhaust side and the air supply side of the diesel engine. When the diesel engine is operated in a low rotational speed range, a part of the compressed air on the air supply side is supplied to the air supply bypass passage. , The pressure on the exhaust side can be increased, whereby the EGR amount can be increased while maintaining the excess air ratio, and the output can be improved.
(2) By providing a check valve in the air supply bypass passage, it is possible to reliably prevent exhaust gas from flowing back from the exhaust side to the air supply side through the air supply bypass passage.
(3) The configuration in which the flow control valve is provided at a position downstream of the check valve in the air supply bypass passage allows the flow of the compressed air to the exhaust side by appropriately selecting the opening of the flow control valve. Can be prevented, and stable operation can be performed.
(4) By making the connection position of the air supply bypass passage close to the turbine inlet and the compressor outlet and the circulation passage close to the diesel engine, rich exhaust gas can be efficiently supplied to the air supply passage. NOx can be further reduced because the diesel engine can be supercharged by inflow.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of an exhaust gas recirculation device for a supercharged diesel engine according to the present invention.
FIG. 2 is a schematic view showing an example of a conventional supercharged diesel engine employing an exhaust gas recirculation system.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 supercharger 2 turbine 3 compressor 4 diesel engine 7 exhaust passage 8 supply passage 9 exhaust gas 10 compressed air 11 circulation passage 16 supply bypass passage 17 check valve 18 flow control valve

Claims (4)

ディーゼルエンジンの給気通路に過給機の圧縮機出口を接続すると共に、ディーゼルエンジンの排気通路を過給機のタービン入口に接続し、上記ディーゼルエンジンの排気ガスの一部を循環通路を通し給気側に戻して再循環させるようにしてある過給ディーゼルエンジンの排気ガス再循環装置において、上記ディーゼルエンジンの排気側と給気側との間に、給気側の圧縮空気の一部を排気側へ流すようにする給気バイパス通路を接続して設けた構成を有することを特徴とする過給ディーゼルエンジンの排気ガス再循環装置。The compressor outlet of the supercharger is connected to the supply passage of the diesel engine, the exhaust passage of the diesel engine is connected to the turbine inlet of the supercharger, and part of the exhaust gas of the diesel engine is supplied through the circulation passage. In the exhaust gas recirculation system for a supercharged diesel engine, which is returned to the gas side and recirculated, a part of the compressed air on the supply side is exhausted between the exhaust side and the supply side of the diesel engine. An exhaust gas recirculation device for a supercharged diesel engine, characterized in that the exhaust gas recirculation device has a configuration in which an air supply bypass passage for flowing to a side is provided. 給気バイパス通路に逆止弁を設けた請求項１記載の過給ディーゼルエンジンの排気ガス再循環装置。The exhaust gas recirculation system for a supercharged diesel engine according to claim 1, wherein a check valve is provided in the air supply bypass passage. 給気バイパス通路の逆止弁よりも下流位置に流量調整弁を設けた請求項２記載の過給ディーゼルエンジンの排気ガス再循環装置。3. The exhaust gas recirculation system for a supercharged diesel engine according to claim 2, wherein a flow control valve is provided at a position downstream of the check valve in the air supply bypass passage. 給気バイパス通路の接続位置をタービン入口及び圧縮機出口に近い位置とし、循環通路の位置をディーゼルエンジンに近い位置とした請求項１、２又は３記載の過給ディーゼルエンジンの排気ガス再循環装置。4. The exhaust gas recirculation system for a supercharged diesel engine according to claim 1, wherein the connection position of the air supply bypass passage is located near the turbine inlet and the compressor outlet, and the circulation passage is located near the diesel engine. .
JP2002177455A 2002-06-18 2002-06-18 Exhaust gas recirculation equipment for supercharging diesel engine Pending JP2004019589A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006095789A1 (en) * 2005-03-09 2006-09-14 Komatsu Ltd. Supercharged engine with egr device
JP2008542613A (en) * 2005-06-02 2008-11-27 ワルトシラ フィンランド オサケユキチュア Method and apparatus for a piston engine with a turbocharger
GB2504713B (en) * 2012-08-07 2017-07-12 Gm Global Tech Operations Llc Turbocharger by-pass system
DE102013112784B4 (en) * 2013-02-28 2020-07-30 Hyundai Motor Company CHARGING SYSTEM FOR COMBUSTION ENGINE

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006095789A1 (en) * 2005-03-09 2006-09-14 Komatsu Ltd. Supercharged engine with egr device
GB2438360A (en) * 2005-03-09 2007-11-21 Komatsu Mfg Co Ltd Supercharged engine with egr device
JPWO2006095789A1 (en) * 2005-03-09 2008-08-14 株式会社小松製作所 Supercharged engine with EGR device
GB2438360B (en) * 2005-03-09 2009-03-04 Komatsu Mfg Co Ltd Supercharged engine with egr device
JP4496248B2 (en) * 2005-03-09 2010-07-07 株式会社小松製作所 Supercharged engine with EGR device
US8001780B2 (en) 2005-03-09 2011-08-23 Komatsu Ltd. Supercharged engine with EGR device
JP2008542613A (en) * 2005-06-02 2008-11-27 ワルトシラ フィンランド オサケユキチュア Method and apparatus for a piston engine with a turbocharger
US8109093B2 (en) 2005-06-02 2012-02-07 Wärtsilä Finland Oy Method and an arrangement in connection with a turbocharged piston engine
JP4896968B2 (en) * 2005-06-02 2012-03-14 ワルトシラ フィンランド オサケユキチュア Method for a piston engine with a turbocharger
GB2504713B (en) * 2012-08-07 2017-07-12 Gm Global Tech Operations Llc Turbocharger by-pass system
DE102013112784B4 (en) * 2013-02-28 2020-07-30 Hyundai Motor Company CHARGING SYSTEM FOR COMBUSTION ENGINE

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