JP4566093B2 - Multi-cylinder engine - Google Patents

Multi-cylinder engine Download PDF

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JP4566093B2
JP4566093B2 JP2005248938A JP2005248938A JP4566093B2 JP 4566093 B2 JP4566093 B2 JP 4566093B2 JP 2005248938 A JP2005248938 A JP 2005248938A JP 2005248938 A JP2005248938 A JP 2005248938A JP 4566093 B2 JP4566093 B2 JP 4566093B2
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passage
exhaust
downstream
intake
egr
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JP2007064043A (en
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秀一 中村
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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
    • F02M26/42—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories having two or more EGR passages; EGR systems specially adapted for engines having two or more cylinders
    • F02M26/44—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories having two or more EGR passages; EGR systems specially adapted for engines having two or more cylinders in which a main EGR passage is branched into multiple passages
    • 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
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/09—Constructional details, e.g. structural combinations of EGR systems and supercharger systems; Arrangement of the EGR and supercharger systems with respect to the engine
    • F02M26/10—Constructional details, e.g. structural combinations of EGR systems and supercharger systems; Arrangement of the EGR and supercharger systems with respect to the engine having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust 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
    • F02M26/13—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)

Description

この発明は、ターボ過給機のタービン上流からターボ過給機のコンプレッサ下流へ排気の一部を環流させる多気筒エンジンに関する。   The present invention relates to a multi-cylinder engine that circulates part of exhaust gas from a turbine upstream of a turbocharger to a compressor downstream of the turbocharger.

ターボ過給機のタービン上流からターボ過給機のコンプレッサ下流へ排気の一部を環流させる多気筒エンジンにおいては、過給圧が排気圧よりも高くなる運転領域があり、排気環流（EGR：Exhaust Gas Recirculation)が十分に行えない。そのため、２つの排気コレクタ（マニホールド）を備えるエンジンにおいて、２つの排気コレクタからのEGRガス（排気の一部）を合流させる混合区間を設定したものが開示される（特許文献１）。混合区間により、EGRガスが加速され、排気コレクタ間を一方の高圧側から他方の低圧側へ排気が逃げるのを抑えられ、混合区間下流へ排気パルスを効率よく伝えられるのである。
特開２００１−１０７８１０号 In a multi-cylinder engine that recirculates part of the exhaust from the turbocharger turbine upstream to the turbocharger compressor downstream, there is an operating region where the supercharging pressure is higher than the exhaust pressure. Gas recirculation) cannot be performed sufficiently. Therefore, an engine having two exhaust collectors (manifolds) is disclosed in which a mixing section in which EGR gas (part of exhaust) from the two exhaust collectors is merged is disclosed (Patent Document 1). The EGR gas is accelerated by the mixing section, the exhaust gas is prevented from escaping from one high pressure side to the other low pressure side between the exhaust collectors, and the exhaust pulse is efficiently transmitted to the downstream of the mixing section.
JP 2001-107810 A

特許文献１の場合、２つの排気コネクタは、ターボ過給機のタービン入口に接続される。ターボ過給機については、２つの排気コネクタに対応する２つのタービン入口を持つタイプに制約されるのである。タービン入口が１つの場合（例えば、可変ノズル式ターボチャージャ）、タービンハウジングの内部で排気の圧力どうしが干渉するため、タービン効率を良好に維持しえないばかりでなく、２つの排気コレクタ内の排気干渉により、混合区間の良好な効果（EGR率の向上）も有効に確保しえなくなってしまう。   In Patent Document 1, the two exhaust connectors are connected to the turbine inlet of the turbocharger. The turbocharger is restricted to a type having two turbine inlets corresponding to two exhaust connectors. In the case of a single turbine inlet (for example, a variable nozzle turbocharger), exhaust pressures interfere with each other inside the turbine housing, so that the turbine efficiency cannot be maintained well, and the exhaust in the two exhaust collectors Due to the interference, the good effect of the mixing section (improvement of the EGR rate) cannot be effectively secured.

この発明は、タービン入口が１つのターボ過給機を備える多気筒エンジンにおいても、タービン効率およびEGR率を有効に高めえる手段の提供を目的とする。   An object of the present invention is to provide means for effectively increasing the turbine efficiency and the EGR rate even in a multi-cylinder engine having a turbocharger having one turbine inlet.

第１の発明は、エンジン排気通路のターボ過給機のタービン上流からエンジン吸気通路のターボ過給機のコンプレッサ下流へ排気の一部を環流させるEGR通路を備える多気筒エンジンにおいて、前記排気通路は、排気行程がオーバラップしない気筒群毎に排気マニホールドを分割し、これらの合流部に前記ターボ過給機のタービンハウジングを接続し、各排気マニホールドの下流側がこれらの合流部へ向けて先細ノズル形状の流路部に形成される一方、前記EGR通路は、上流側の分岐路と下流側の合流路とからなり、前記合流路にEGRクーラ、その下流にEGRバルブ、さらにその下流にリードバルブを介装し、各分岐路がこれらの合流部へ向けて先細ノズル形状の流路部に形成されるものにあって、前記エンジン吸気通路は、吸気マニホールドと吸気管とからなり、吸気マニホールドは吸気行程がオーバラップしない気筒群毎に分割し、吸気管は、インタクーラ下流側でEGR通路の接続する部位下流が分岐されそれぞれ前記吸気マニホールドに接続することを特徴とする。 A first invention is a multi-cylinder engine having an EGR passage that circulates a part of exhaust from a turbine upstream of a turbocharger in an engine exhaust passage to a compressor downstream of a turbocharger in an engine intake passage. The exhaust manifold is divided for each cylinder group where the exhaust strokes do not overlap, the turbine housing of the turbocharger is connected to these merging portions, and the downstream side of each exhaust manifold is tapered toward these merging portions The EGR passage is composed of an upstream branch passage and a downstream combined passage, and an EGR cooler in the combined passage, an EGR valve downstream thereof, and a reed valve downstream thereof. interposed, in the which the branch path is formed in the flow path of the nozzle shape tapering towards these merging section, the engine intake passage, the intake and the intake manifold Consists of a intake manifold intake stroke is divided for each cylinder group do not overlap, the intake pipe, site downstream connecting the EGR passage intercooler downstream, characterized in that connected to the respective branches the intake manifold .

第２の発明は、エンジン排気通路のターボ過給機のタービン上流からエンジン吸気通路のターボ過給機のコンプレッサ下流へ排気の一部を環流させるEGR通路を備える多気筒エンジンにおいて、前記排気通路は、排気行程がオーバラップしない気筒群毎に排気マニホールドを分割し、これらの合流部に前記ターボ過給機のタービンハウジングを接続し、各排気マニホールドの下流側がこれらの合流部へ向けて先細ノズル形状の流路部に形成される一方、前記EGR通路は、上流側の分岐路と下流側の合流路とからなり、前記合流路にEGRクーラ、その下流にEGRバルブを介装し、各分岐路がこれらの合流部へ向けて先細ノズル形状の流路部に形成され、前記吸気通路は、ターボ過給機のコンプレッサ下流にベンチュリ部を通過する吸気の流れによってEGRガスを吸引するエゼクタが介装されるものにあって、前記エンジン吸気通路は、吸気マニホールドと吸気管とからなり、吸気マニホールドは吸気行程がオーバラップしない気筒群毎に分割し、吸気管は、インタクーラ下流側でEGR通路の接続するエゼクタ下流が分岐されそれぞれ前記吸気マニホールドに接続することを特徴とする。 According to a second aspect of the present invention, in the multi-cylinder engine having an EGR passage for circulating a part of the exhaust from the turbine upstream of the turbocharger in the engine exhaust passage to the compressor downstream of the turbocharger in the engine intake passage, The exhaust manifold is divided for each cylinder group where the exhaust strokes do not overlap, the turbine housing of the turbocharger is connected to these merging portions, and the downstream side of each exhaust manifold is tapered toward these merging portions On the other hand, the EGR passage is composed of an upstream branch passage and a downstream joint passage, and the branch passage is provided with an EGR cooler in the joint passage and an EGR valve downstream thereof. Are formed in the flow path portion of the tapered nozzle shape toward these merging portions, and the intake passage is EGR by the flow of the intake air passing through the venturi portion downstream of the turbocharger compressor. In the one ejector for sucking the scan is interposed, the engine intake passage is composed of an intake manifold and the intake pipe, the intake manifold is divided for each cylinder group at which the intake stroke does not overlap the intake pipe, The ejector downstream to which the EGR passage is connected is branched on the downstream side of the intercooler, and each branch is connected to the intake manifold .

第３の発明は、第１の発明または第２の発明に係る多気筒エンジンにおいて、前記ターボ過給機は、可変ノズル式ターボチャージャを用いたことを特徴とする。 According to a third invention, in the multi-cylinder engine according to the first or second invention, the turbocharger uses a variable nozzle type turbocharger .

第１、第３の発明においては、エンジンの排気は、各排気マニホールドにより、排気行程のオーバラップしない気筒群毎に分けられ、合流部からターボ過給機のタービンへ流れる。その際、先細ノズル形状の流路部により、排気パルスが加速され、合流部に吹き出る排気の流速により、合流部の静圧が下がるため、各排気マニホールド間を排気が低圧側へ逆流するのが抑えられ、排気パルスも逃げることなく下流へ伝えられる。EGR通路においても、先細ノズル形状の流路部により、排気パルスが加速され、合流部に吹き出る排気の流速により、合流部の静圧が下がるため、各分岐路間を排気が低圧側へ逆流するのが抑えられ、排気パルスも逃げることなく下流へ伝えられる。このため、ターボ過給機のタービン入口が１つの場合においても、排気パルスが十分に生かせるようになり、タービン効率およびEGR効率を良好に維持しえることになる。排気マニホールドの合流部およびEGR通路の合流部におけるエゼクタ作用により、ポンピングロスが低減され、NOxを低減しつつ、燃費や出力の向上が得られる。EGRガスは、ターボ過給機のタービン下流の各排気マニホールドから分岐路および合流路を通してターボ過給機のコンプレッサ下流へ供給され、合流路において、EGRクーラによって冷却され、EGRバルブによってEGR量が調整され、リードバルブによってEGRガスの逆流が規制される。EGRバルブおよびリードバルブは、EGRクーラの下流側に配置するので、耐久性も良好に確保される。 In the first and third aspects of the invention , engine exhaust is divided by the exhaust manifolds into cylinder groups that do not overlap in the exhaust stroke, and flows from the junction to the turbine of the turbocharger. At that time, the exhaust nozzle is accelerated by the tapered nozzle-shaped flow path section, and the static pressure of the merging section is lowered by the flow velocity of the exhaust gas blown out to the merging section, so that the exhaust gas flows back to the low pressure side between the exhaust manifolds. The exhaust pulse is transmitted downstream without escaping. Also in the EGR passage, the exhaust pulse is accelerated by the tapered nozzle-shaped flow path section, and the static pressure of the merge section decreases due to the flow velocity of the exhaust gas blown out to the merge section, so that the exhaust gas flows back to the low pressure side between the branch paths. And the exhaust pulse is transmitted downstream without escaping. For this reason, even when there is one turbine inlet of the turbocharger, the exhaust pulse can be fully utilized, and the turbine efficiency and the EGR efficiency can be maintained well. The ejector action at the merging portion of the exhaust manifold and the merging portion of the EGR passage reduces the pumping loss and reduces NOx while improving fuel efficiency and output. EGR gas is supplied from each exhaust manifold downstream of the turbocharger turbine to the downstream of the turbocharger compressor through the branch and combined flow paths, cooled in the combined flow path by the EGR cooler, and adjusted by the EGR valve. The reflow of EGR gas is regulated by the reed valve. Since the EGR valve and the reed valve are arranged on the downstream side of the EGR cooler, good durability is ensured.

第２、第３の発明においては、エンジンの排気は、各排気マニホールドにより、排気行程のオーバラップしない気筒群毎に分けられ、合流部からターボ過給機のタービンへ流れる。その際、先細ノズル形状の流路部により、排気パルスが加速され、合流部に吹き出る排気の流速により、合流部の静圧が下がるため、各排気マニホールド間を排気が低圧側へ逆流するのが抑えられ、排気パルスも逃げることなく下流へ伝えられる。EGR通路においても、先細ノズル形状の流路部により、排気パルスが加速され、合流部に吹き出る排気の流速により、合流部の静圧が下がるため、各分岐路間を排気が低圧側へ逆流するのが抑えられ、排気パルスも逃げることなく下流へ伝えられる。このため、ターボ過給機のタービン入口が１つの場合においても、排気パルスが十分に生かせるようになり、タービン効率およびEGR効率を良好に維持しえることになる。排気マニホールドの合流部およびEGR通路の合流部におけるエゼクタ作用により、ポンピングロスが低減され、NOxを低減しつつ、燃費や出力の向上が得られる。EGRガスは、ターボ過給機のタービン下流の各排気マニホールドから分岐路および合流路を流れ、吸気通路のエゼクタによって吸引されるようになる。合流路においては、EGRクーラによって冷却され、EGRバルブによってEGR量が調整される。EGRバルブは、EGRクーラの下流側に配置するので、耐久性も良好に確保される。 In the second and third aspects of the invention , engine exhaust is divided by the exhaust manifolds into cylinder groups that do not overlap in the exhaust stroke, and flows from the junction to the turbine of the turbocharger. At that time, the exhaust nozzle is accelerated by the tapered nozzle-shaped flow path section, and the static pressure of the merging section is lowered by the flow velocity of the exhaust gas blown out to the merging section. The exhaust pulse is transmitted downstream without escaping. Also in the EGR passage, the exhaust pulse is accelerated by the tapered nozzle-shaped flow path section, and the static pressure of the merge section decreases due to the flow velocity of the exhaust gas blown out to the merge section, so that the exhaust gas flows back to the low pressure side between the branch paths. And the exhaust pulse is transmitted downstream without escaping. For this reason, even when there is one turbine inlet of the turbocharger, the exhaust pulse can be fully utilized, and the turbine efficiency and the EGR efficiency can be maintained well. The ejector action at the merging portion of the exhaust manifold and the merging portion of the EGR passage reduces the pumping loss and reduces NOx while improving fuel efficiency and output. The EGR gas flows from the exhaust manifolds downstream of the turbocharger turbine through the branch passage and the combined passage, and is sucked by the ejector in the intake passage. The combined flow path is cooled by the EGR cooler, and the EGR amount is adjusted by the EGR valve. Since the EGR valve is arranged on the downstream side of the EGR cooler, good durability is ensured.

第１の発明または第２の発明に係るEGR通路は、吸気管の分岐部上流に接続される（図１または図７、参照）。 The EGR passage according to the first invention or the second invention is connected upstream of the branch portion of the intake pipe (see FIG. 1 or FIG. 7).

第３の発明においては、可変ノズル式ターボチャージャを備えるので、可変ノズルの制御により、広い運転領域において、高過給および高EGRが可能となり、低NOxと低燃費との高度な両立を実現できる。 In the third aspect of the invention , since the variable nozzle type turbocharger is provided, it is possible to achieve high supercharging and high EGR in a wide operation range by controlling the variable nozzle, and to achieve a high degree of compatibility between low NOx and low fuel consumption. .

図１において、１０はエンジン１の吸気通路であり、吸気マニホールド１４と吸気管１５とから構成される。吸気マニホールド１４は、吸気行程がオーバラップしない気筒群毎に分割される。吸気管１５は、インタクーラ１３下流側が分岐され、各マニホールド１４ａ，１４ｂに接続される。１２ａはターボ過給機１２のコンプレッサであり、１１はエアクリーナである。   In FIG. 1, reference numeral 10 denotes an intake passage of the engine 1 and includes an intake manifold 14 and an intake pipe 15. The intake manifold 14 is divided for each cylinder group in which the intake strokes do not overlap. The intake pipe 15 is branched downstream of the intercooler 13 and connected to the manifolds 14a and 14b. 12a is a compressor of the turbocharger 12, and 11 is an air cleaner.

２０はエンジン１の排気通路であり、排気マニホールド２３と排気管２２とから構成される。排気マニホールド２３は、排気行程がオーバラップしない気筒群毎に分割され、これらマニホールド２３ａ，２３ｂの合流部２５にターボ過給機１２のタービン１２ａを介して排気管２２が接続される。２１はマフラである。   Reference numeral 20 denotes an exhaust passage of the engine 1 and includes an exhaust manifold 23 and an exhaust pipe 22. The exhaust manifold 23 is divided for each cylinder group in which the exhaust strokes do not overlap, and the exhaust pipe 22 is connected to the merging portion 25 of these manifolds 23a and 23b via the turbine 12a of the turbocharger 12. 21 is a muffler.

合流部２５は、図２のように構成される。排気マニホールド２３ａ，２３ｂは、互いに下流側が１つの接合部２４（フランジ）に結集され、合流部２５を接合面に開口する。１つの接合部２４に結集する下流側の流路部２６ａ，２６ｂが接合面の開口へ向けて先細ノズル形状になっている。３０はタービンハウジングであり、排気マニホールド２３ａ，２３ｂの接合部２４（フランジ）に対応する接合部３１（フランジ）が形成され、タービン１２ｂの入口が接合面に開口する。排気マニホールド２３ａ，２３ｂの接合部２４にタービンハウジング３０の接合部３１が結合され、タービンハウジング３０の内部へ接合面の開口（合流部２５）を滑らかに延長するディフューザ部３３が形成される。   The junction 25 is configured as shown in FIG. The exhaust manifolds 23a and 23b are gathered together at one joint 24 (flange) on the downstream side, and the junction 25 is opened to the joint surface. The downstream flow path portions 26a and 26b gathered in one joint portion 24 have a tapered nozzle shape toward the opening of the joint surface. A turbine housing 30 is formed with a joint 31 (flange) corresponding to the joint 24 (flange) of the exhaust manifolds 23a and 23b, and the inlet of the turbine 12b opens to the joint surface. A joint portion 31 of the turbine housing 30 is coupled to the joint portion 24 of the exhaust manifolds 23a and 23b, and a diffuser portion 33 that smoothly extends the opening (junction portion 25) of the joint surface into the turbine housing 30 is formed.

この場合、ターボ過給機１２として、可変ノズル式ターボチャージャが用いられ、合流部２５の最小流面積はタービンハウジング３０の内部に設定され、最小流路面積の下流側（流路）が可変ノズル３２を囲むスクロールへ拡張するように形成される。合流部２５の最小流路面積は、先細ノズル形状の流路部２６ａ，２６ｂの最大流路面積の総和よりも小さく設定され、先細ノズル形状の流路部２６ａ，２６ｂにより、排気パルスが加速され、合流部２５において、先細ノズル形状の流路部２６ａ，２６ｂから吹き出る排気の流速によって動圧が上がり、静圧が下げられ、その後、ディフューザ部３３により、排気の流れが減速され、スクロールの静圧を上げるようになっている。ターボ過給機１２のコンプレッサ１２ａは、タービン１２ｂの回転により駆動され、各気筒への吸気を過給する。   In this case, a variable nozzle type turbocharger is used as the turbocharger 12, the minimum flow area of the merging portion 25 is set inside the turbine housing 30, and the downstream side (flow path) of the minimum flow area is a variable nozzle. It is formed to expand to a scroll surrounding 32. The minimum flow area of the merging section 25 is set smaller than the sum of the maximum flow areas of the tapered nozzle-shaped flow paths 26a and 26b, and the exhaust pulse is accelerated by the tapered nozzle-shaped flow paths 26a and 26b. In the merging portion 25, the dynamic pressure is increased and the static pressure is lowered by the flow velocity of the exhaust gas blown out from the tapered nozzle-shaped flow passage portions 26a and 26b, and then the flow of the exhaust gas is decelerated by the diffuser portion 33, and the static flow of the scroll is reduced. Increase the pressure. The compressor 12a of the turbocharger 12 is driven by the rotation of the turbine 12b and supercharges intake air to each cylinder.

図１において、４０はターボ過給機１２のタービン１２ｂ上流からターボ過給機１２のコンプレッサ１２ａ下流へ排気の一部を環流させるEGR通路であり、上流側の分岐路４０ａ，４０ｂと下流側の合流路４０ｃとからなり、分岐路４０ａ，４０ｂがそれぞれ排気マニホールド２３ａ，２３ｂに接続され、合流路４０ｃがインタクーラ１３下流の吸気管１５に接続される。合流路４０ｃにおいて、EGRガスを冷却するEGRクーラ４１、EGR量を調整するEGRバルブ４２、EGRガスの逆流を規制するリードバルブ４３が介装される。   In FIG. 1, reference numeral 40 denotes an EGR passage that circulates part of the exhaust gas from the upstream side of the turbine 12b of the turbocharger 12 to the downstream side of the compressor 12a of the turbocharger 12, and the upstream side branch paths 40a and 40b and the downstream side The combined flow path 40c includes branch paths 40a and 40b connected to the exhaust manifolds 23a and 23b, respectively, and the combined flow path 40c connected to the intake pipe 15 downstream of the intercooler 13. In the combined flow path 40c, an EGR cooler 41 for cooling the EGR gas, an EGR valve 42 for adjusting the EGR amount, and a reed valve 43 for regulating the backflow of the EGR gas are interposed.

分岐路４０ａ，４０ｂの合流部４５は、図３のように構成される。分岐路４０ａ，４０ｂは、互いに下流側が１つの接合部４６（フランジ）に結集され、接合面にそれぞれ開口する。１つの接合部４６に結集する下流側の流路部４４ａ，４４ｂが接合面の開口へ向けて先細ノズル形状になっている。５０はEGRクーラ４１のケーシングであり、分岐路４０ａ，４０ｂの接合部４６（フランジ）に対応する接合部５１（フランジ）が形成され、EGRクーラ４１の入口が接合面に開口する。分岐路４０ａ，４０ｂの接合部４６にケーシング５０の接合部５１が結合され、ケージング５０の内部へ接合面の開口（合流部４５）を滑らかに延長するディフューザ部（図示せず）が形成される。分岐路４０ａ，４０ｂは、排気マニホールド２３ａ，２３ｂに接合部４７ａ，４７ｂ（フランジ）を介して直接的または間接的に接続されるのである。   The junction 45 of the branch paths 40a and 40b is configured as shown in FIG. The branch paths 40a and 40b are gathered together at one joint 46 (flange) on the downstream side and open to the joint surfaces. Downstream flow path portions 44a and 44b that converge at one joint portion 46 are tapered toward the opening of the joint surface. Reference numeral 50 denotes a casing of the EGR cooler 41, in which a joint portion 51 (flange) corresponding to the joint portion 46 (flange) of the branch paths 40a and 40b is formed, and the inlet of the EGR cooler 41 opens to the joint surface. The joint portion 51 of the casing 50 is joined to the joint portion 46 of the branch paths 40a and 40b, and a diffuser portion (not shown) that smoothly extends the opening (junction portion 45) of the joint surface into the casing 50 is formed. . The branch paths 40a and 40b are directly or indirectly connected to the exhaust manifolds 23a and 23b via joints 47a and 47b (flange).

合流部４５の最小流路面積は、先細ノズル形状の流路部の最大流路面積の総和よりも小さく設定され、先細ノズル形状の流路部４４ａ，４４ｂにより、排気パルスが加速され、合流部４５において、先細ノズル形状の流路部４４ａ，４４ｂから吹き出る排気の流速によって動圧が上がり、静圧が下げられ、その後、ディフューザ部により、排気の流れが減速され、クーラコア前面の静圧を上げるようになっている。   The minimum flow area of the merging section 45 is set smaller than the sum of the maximum flow areas of the tapered nozzle-shaped flow path sections, and the exhaust pulse is accelerated by the tapered nozzle-shaped flow path sections 44a and 44b. In 45, the dynamic pressure is increased and the static pressure is lowered by the flow velocity of the exhaust gas blown out from the tapered nozzle-shaped flow path portions 44a and 44b, and then the flow of the exhaust gas is decelerated by the diffuser portion and the static pressure on the front surface of the cooler core is increased. It is like that.

このような構成により、排気マニホールド２３ａ，２３ｂの合流部２５において、静圧が下がることにより、排気マニホールド２３ａ，２３ｂ間を排気が低圧側へ逆流することが抑えられ、排気パルスも低圧側へ逃げることがなく下流へ伝えられる。また、EGR通路４０の合流部４５において、静圧が下がることにより、分岐路４０ａ，４０ｂ間を排気が低圧側へ逆流することが抑えられ、排気パルスも低圧側へ逃げることがなく下流へ伝えられる。このため、タービン入口が１つの可変ノズル式ターボチャージャ１２においても、排気パルスが十分に生かせるようになり、タービン効率およびEGR効率を良好に維持しえることになる。合流部２５，４５におけるエゼクタ作用により、ポンピングロスが低減され、NOxを低減しつつ、燃費や出力の向上が得られる。   With such a configuration, the static pressure is reduced at the junction 25 of the exhaust manifolds 23a and 23b, so that the exhaust gas is prevented from flowing back to the low pressure side between the exhaust manifolds 23a and 23b, and the exhaust pulse also escapes to the low pressure side. It is transmitted downstream without any problems. In addition, the static pressure is reduced at the junction 45 of the EGR passage 40, so that the exhaust gas is prevented from flowing back to the low pressure side between the branch paths 40a and 40b, and the exhaust pulse is transmitted downstream without escaping to the low pressure side. It is done. For this reason, even in the variable nozzle turbocharger 12 having one turbine inlet, the exhaust pulse can be fully utilized, and the turbine efficiency and the EGR efficiency can be maintained well. Pumping loss is reduced by the ejector action in the merging portions 25 and 45, and NOx is reduced while improving fuel consumption and output.

可変ノズル式ターボチャージャ１２を備えるため、可変ノズルの制御により、広い運転領域において、高過給および高EGRが可能となり、低NOxと低燃費との高度な両立を実現できるのである。EGR通路４０においては、EGRクーラ４１の入口に分岐路４０ａ，４０ｂが接続され、EGRバルブ４２およびリードバルブ４３をEGRクーラ４１の下流側に配置するので、これらバルブ４２，４３の耐久性も良好に確保される。   Since the variable nozzle type turbocharger 12 is provided, the control of the variable nozzle enables high supercharging and high EGR in a wide operation range, and it is possible to achieve a high degree of compatibility between low NOx and low fuel consumption. In the EGR passage 40, branch paths 40a and 40b are connected to the inlet of the EGR cooler 41, and the EGR valve 42 and the reed valve 43 are disposed downstream of the EGR cooler 41. Therefore, the durability of the valves 42 and 43 is also good. Secured.

排気系において、ディフューザ部３３は、タービンハウジング３０と一体に形成するのでなく、図４のように別体のスペーサとしてタービンハウジング３０の接合部３１（フランジ）と排気マニホールド２３ａ，２３ｂの接合部２４（フランジ）との間に介装してもよい。先細ノズル形状の流路部２６ａ，２６ｂについても、排気マニホールド２３ａ，２３ｂと一体に形成するのでなく、図５のように別体のスペーサとして排気マニホールド２３ａ，２３ｂの接合部２４（フランジ）とタービンハウジング３０の接合部 ３１（フランジ）との間に介装してもよい。EGR系において、分岐路４０ａ，４０ｂは、EGRクーラ４１のケーシング５０と別体に形成するのでなく、図６のようにケーシング５０と一体に形成してもよい。   In the exhaust system, the diffuser portion 33 is not formed integrally with the turbine housing 30, but as a separate spacer as shown in FIG. 4, the joint portion 31 (flange) of the turbine housing 30 and the joint portion 24 of the exhaust manifolds 23a and 23b. (Flange) may be interposed. The tapered nozzle-shaped flow passage portions 26a and 26b are not formed integrally with the exhaust manifolds 23a and 23b, but are joined to the joint portions 24 (flange) of the exhaust manifolds 23a and 23b and the turbine as separate spacers as shown in FIG. You may interpose between the junction parts 31 (flange) of the housing 30. FIG. In the EGR system, the branch paths 40a and 40b may be formed integrally with the casing 50 as shown in FIG. 6 instead of being formed separately from the casing 50 of the EGR cooler 41.

図７は、別の実施形態を表すものであり、吸気管１５において、EGR通路４０との接続部にベンチュリ型のエゼクタ６０が設けられる。これにより、ベンチュリ部を通過する吸気の流速に応じた負圧が発生するので、この負圧に吸引され、EGRガスがエゼクタ６０へ効率よく供給しえるようになる。この場合、リードバルブ４３（図１、参照）は、EGR通路４０から取り外される。他の構成は、図１の実施形態と実質的に同一のため、同一の符号を付ける。 FIG. 7 shows another embodiment. In the intake pipe 15, a venturi-type ejector 60 is provided at a connection portion with the EGR passage 40. As a result, a negative pressure corresponding to the flow velocity of the intake air passing through the venturi is generated, so that the negative pressure is sucked and the EGR gas can be efficiently supplied to the ejector 60. In this case, the reed valve 43 (see FIG. 1) is removed from the EGR passage 40. Other configurations are substantially the same as those of the embodiment of FIG.

この発明の実施形態を表す全体的な概略構成図である。1 is an overall schematic configuration diagram illustrating an embodiment of the present invention. 同じく排気マニホールドの合流部に係る構成図である。It is the block diagram which similarly concerns on the confluence | merging part of an exhaust manifold. 同じくEGR通路の合流部に係る構成図である。It is a block diagram similarly concerning the confluence | merging part of an EGR channel | path. 同じく排気マニホールドの合流部に係る構成図である。It is the block diagram which similarly concerns on the confluence | merging part of an exhaust manifold. 同じく排気マニホールドの合流部に係る構成図である。It is the block diagram which similarly concerns on the confluence | merging part of an exhaust manifold. 同じくEGR通路の合流部に係る構成図である。It is a block diagram similarly concerning the confluence | merging part of an EGR channel | path. 別の実施形態を表す全体的な概略構成図である。It is a whole schematic block diagram showing another embodiment.

符号の説明Explanation of symbols

１２ ターボ過給機（可変ノズル式ターボチャージャ）
１３ インタクーラ
２３，２３ａ，２３ｂ 排気マニホールド
２５ 合流部（排気通路）
２６ａ，２６ｂ 先細ノズル形状の流路部（排気通路）
３０ タービンハウジング
３３ ディフューザ部
４０ EGR通路
４０ａ，４０ｂ 分岐路
４０ｃ 合流路（EGR通路）
４１ EGRクーラ
４４ａ，４４ｂ 先細ノズル形状の流路部（EGR通路）
４５ 合流部 12 Turbocharger (variable nozzle turbocharger)
13 Intercooler 23, 23a, 23b Exhaust manifold 25 Junction (exhaust passage)
26a, 26b Tapered nozzle-shaped channel section (exhaust passage)
30 Turbine housing 33 Diffuser part 40 EGR passage 40a, 40b Branch passage 40c Joint passage (EGR passage)
41 EGR cooler 44a, 44b Tapered nozzle shaped flow path (EGR passage)
45 Junction

Claims (3)

エンジン排気通路のターボ過給機のタービン上流からエンジン吸気通路のターボ過給機のコンプレッサ下流へ排気の一部を環流させるEGR通路を備える多気筒エンジンにおいて、前記排気通路は、排気行程がオーバラップしない気筒群毎に排気マニホールドを分割し、これらの合流部に前記ターボ過給機のタービンハウジングを接続し、各排気マニホールドの下流側がこれらの合流部へ向けて先細ノズル形状の流路部に形成される一方、前記EGR通路は、上流側の分岐路と下流側の合流路とからなり、前記合流路にEGRクーラ、その下流にEGRバルブ、さらにその下流にリードバルブを介装し、各分岐路がこれらの合流部へ向けて先細ノズル形状の流路部に形成されるものにあって、前記エンジン吸気通路は、吸気マニホールドと吸気管とからなり、吸気マニホールドは吸気行程がオーバラップしない気筒群毎に分割し、吸気管は、インタクーラ下流側でEGR通路の接続する部位下流が分岐されそれぞれ前記吸気マニホールドに接続することを特徴とする多気筒エンジン。
ることを特徴とする多気筒エンジン。 In a multi-cylinder engine having an EGR passage that circulates part of the exhaust from the turbine upstream of the turbocharger in the engine exhaust passage to the compressor downstream of the turbocharger in the engine intake passage, the exhaust passage overlaps the exhaust stroke The exhaust manifold is divided for each cylinder group not to be connected, and the turbine housing of the turbocharger is connected to these merging portions, and the downstream side of each exhaust manifold is formed into a tapered nozzle-shaped flow path portion toward these merging portions. On the other hand, the EGR passage is composed of an upstream branch passage and a downstream joint passage, and an EGR cooler is provided in the joint passage, an EGR valve downstream thereof, and a reed valve downstream thereof. in the what road is formed in the flow path of the nozzle shape tapering towards these merging section, the engine intake passage is composed of an intake manifold and the intake pipe, Air manifold is divided for each cylinder group at which the intake stroke does not overlap, multi-cylinder engine intake pipe, characterized in that the portion downstream of connecting the EGR passage is connected to the respective branches the intake manifold with intercooler downstream.
This is a multi-cylinder engine. エンジン排気通路のターボ過給機のタービン上流からエンジン吸気通路のターボ過給機のコンプレッサ下流へ排気の一部を環流させるEGR通路を備える多気筒エンジンにおいて、前記排気通路は、排気行程がオーバラップしない気筒群毎に排気マニホールドを分割し、これらの合流部に前記ターボ過給機のタービンハウジングを接続し、各排気マニホールドの下流側がこれらの合流部へ向けて先細ノズル形状の流路部に形成される一方、前記EGR通路は、上流側の分岐路と下流側の合流路とからなり、前記合流路にEGRクーラ、その下流にEGRバルブを介装し、各分岐路がこれらの合流部へ向けて先細ノズル形状の流路部に形成され、前記吸気通路は、ターボ過給機のコンプレッサ下流にベンチュリ部を通過する吸気の流れによってEGRガスを吸引するエゼクタが介装されるものにあって、前記エンジン吸気通路は、吸気マニホールドと吸気管とからなり、吸気マニホールドは吸気行程がオーバラップしない気筒群毎に分割し、吸気管は、インタクーラ下流側でEGR通路の接続するエゼクタ下流が分岐されそれぞれ前記吸気マニホールドに接続することを特徴とする多気筒エンジン。 In a multi-cylinder engine having an EGR passage that circulates part of the exhaust from the turbine upstream of the turbocharger in the engine exhaust passage to the compressor downstream of the turbocharger in the engine intake passage, the exhaust passage overlaps the exhaust stroke The exhaust manifold is divided for each cylinder group not to be connected, and the turbine housing of the turbocharger is connected to these merging portions, and the downstream side of each exhaust manifold is formed into a tapered nozzle-shaped flow path portion toward these merging portions. On the other hand, the EGR passage is composed of an upstream branch passage and a downstream joint passage, and an EGR cooler is interposed in the joint passage and an EGR valve downstream thereof, and each branch passage is connected to these junctions. The intake passage is formed in a tapered nozzle-shaped flow path, and the intake passage sucks EGR gas by the flow of intake air passing through the venturi section downstream of the compressor of the turbocharger. In the what injector is interposed, the engine intake passage is composed of an intake manifold and the intake pipe, the intake manifold is divided for each cylinder group at which the intake stroke does not overlap the intake pipe, with an intercooler downstream A multi-cylinder engine characterized in that an ejector downstream to which an EGR passage is connected is branched and connected to the intake manifold . 前記ターボ過給機は、可変ノズル式ターボチャージャを用いたことを特徴とする請求項１または請求項２に記載の多気筒エンジン。 The multi-cylinder engine according to claim 1 , wherein the turbocharger uses a variable nozzle turbocharger .
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