JP3456133B2 - Exhaust gas recirculation system for turbocharged engine - Google Patents

Exhaust gas recirculation system for turbocharged engine

Info

Publication number
JP3456133B2
JP3456133B2 JP35129797A JP35129797A JP3456133B2 JP 3456133 B2 JP3456133 B2 JP 3456133B2 JP 35129797 A JP35129797 A JP 35129797A JP 35129797 A JP35129797 A JP 35129797A JP 3456133 B2 JP3456133 B2 JP 3456133B2
Authority
JP
Japan
Prior art keywords
engine
intake
exhaust gas
egr
combustion chamber
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
JP35129797A
Other languages
Japanese (ja)
Other versions
JPH11182358A (en
Inventor
琢也 北清
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Fuso Truck and Bus Corp
Original Assignee
Mitsubishi Fuso Truck and Bus Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Fuso Truck and Bus Corp filed Critical Mitsubishi Fuso Truck and Bus Corp
Priority to JP35129797A priority Critical patent/JP3456133B2/en
Publication of JPH11182358A publication Critical patent/JPH11182358A/en
Application granted granted Critical
Publication of JP3456133B2 publication Critical patent/JP3456133B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D21/00—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas
    • F02D21/06—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air
    • F02D21/08—Controlling engines characterised by their being supplied with non-airborne oxygen or other non-fuel gas peculiar to engines having other non-fuel gas added to combustion air the other gas being the exhaust gas of engine
    • 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
    • F02M26/17—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system
    • 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
    • F02M26/04—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

Landscapes

  • 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

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、過給機が付いたエ
ンジンに排気ガスの一部を還流させる過給機付エンジン
の排気ガス還流装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation system for a supercharged engine that recirculates a part of exhaust gas to an engine equipped with a supercharger.

【０００２】[0002]

【従来の技術】車両に搭載されるディーゼルエンジン
は、ターボチャージャー（過給機）と組み合わせて、燃
焼室に供給される吸気を過給して、エンジン出力の向上
を図ることが行われている。2. Description of the Related Art A diesel engine mounted on a vehicle is combined with a turbocharger (supercharger) to supercharge intake air supplied to a combustion chamber to improve engine output. .

【０００３】この過給機付ディーゼルエンジンでも、排
気ガス性能を良好、具体的にはＮＯｘ（窒素酸化物）の
排出を低減するために、エンジンの運転状態に応じてエ
ンジンから排出された排気ガスの一部をエンジンの吸気
に戻して還流させる、いわゆるＥＧＲ装置（排気ガス還
流装置）が採用されている。Also in this supercharged diesel engine, the exhaust gas discharged from the engine in accordance with the operating condition of the engine in order to improve the exhaust gas performance, specifically, to reduce the emission of NOx (nitrogen oxide). A so-called EGR device (exhaust gas recirculation device) is used to return a part of the exhaust gas to the intake air of the engine for recirculation.

【０００４】こうした過給機付エンジンのＥＧＲ装置に
は、エンジンの運転領域の全体に渡り、排気ガスを吸気
側に還流させる能力が求められる。ところが、過給機付
エンジンは、エンジン回転数が上昇する程、ターボチャ
ージャーのコンプレッサの回転が高くなって過給圧が高
くなるので、過給圧が排気圧力と同等かそれ以上の圧力
になると、排気ガスを燃焼室に押し込めなくなり、ＥＧ
Ｒ（排気ガス還流）が行えなくなる。The EGR device for such a supercharged engine is required to have the ability to recirculate exhaust gas to the intake side over the entire operating region of the engine. However, in an engine with a supercharger, as the engine speed increases, the rotation of the compressor of the turbocharger increases and the supercharging pressure increases, so when the supercharging pressure becomes equal to or higher than the exhaust pressure. , Exhaust gas cannot be pushed into the combustion chamber, EG
R (exhaust gas recirculation) cannot be performed.

【０００５】そのため、ＥＧＲは、高エンジン出力とな
るエンジンの運転領域［高エンジントルク（高負荷）／
高エンジン回転数（高速側）］では行えず、ＥＧＲが行
える範囲が低・中負荷／低・中速寄りに限定されてい
た。Therefore, the EGR is the operating range [high engine torque (high load) /
High engine speed (high speed side)], and the range of EGR is limited to low / medium load / low / medium speed.

【０００６】そこで、この排気ガスが押し込めなくなる
のを回避するために、エンジンの吸気側の負圧を利用し
て、高エンジントルク／高エンジン回転数寄りでもＥＧ
Ｒ効果が発揮されるようにしたＥＧＲ装置が提案されて
いる。Therefore, in order to prevent the exhaust gas from being pushed in, the negative pressure on the intake side of the engine is used to make the EG even at high engine torque / high engine speed.
An EGR device has been proposed in which the R effect is exhibited.

【０００７】このＥＧＲ装置には、過給した吸気を２つ
の吸気通路でエンジンの燃焼室へ導く構造を用い、この
うちの一方の吸気通路に開閉弁を介装し、この開閉弁の
上流側にＥＧＲ通路の出口を接続した構造が用いられて
いる。そして、過給圧が排気圧力より低いエンジンの運
転領域のときは開閉弁を開にして、ＥＧＲ通路からの排
気ガスを一方の吸気通路を通じて燃焼室へ導入し、過給
圧が排気圧力と同等かそれ以上になるときは開閉弁を閉
にし、開閉弁から燃焼室に至る上流の通路部分に負圧を
作用させて、排気ガスがＥＧＲ通路から燃焼室へ導入さ
れるようにして、高負荷／高回転数寄りでのＥＧＲを実
現するようにしていた。This EGR device uses a structure in which supercharged intake air is guided to the combustion chamber of the engine through two intake passages, and an opening / closing valve is provided in one of the intake passages, and an upstream side of this opening / closing valve is used. The structure in which the outlet of the EGR passage is connected to is used. When the supercharging pressure is lower than the exhaust pressure in the operating region of the engine, the on-off valve is opened and the exhaust gas from the EGR passage is introduced into the combustion chamber through one of the intake passages so that the supercharging pressure is equal to the exhaust pressure. When it becomes higher or higher, the on-off valve is closed and a negative pressure is applied to the upstream passage portion from the on-off valve to the combustion chamber so that the exhaust gas is introduced into the combustion chamber from the EGR passage, thereby increasing the load. / It was designed to achieve EGR near the high rotation speed.

【０００８】[0008]

【発明が解決しようとする課題】ところが、このＥＧＲ
装置でも、燃焼室における空気過剰率λ（＝空気量／理
論混合気）の制約を受けて、ＥＧＲが行える領域には限
界がある。すなわち、理論混合比より濃度の高い空燃比
で燃焼が行われると、燃焼に必要な酸素が不足している
ので、黒煙などが発生して、排気ガス性能が悪くなる。
このため、ＥＧＲは、吸気通路の片方から過給される吸
気によって、燃焼室の空燃比が薄い状態に保たれている
間しか行えない。However, this EGR
Even in the apparatus, there is a limit to the region where EGR can be performed due to the restriction of the excess air ratio λ (= air amount / theoretical mixture) in the combustion chamber. That is, when combustion is performed at an air-fuel ratio having a concentration higher than the stoichiometric mixture ratio, oxygen required for combustion is insufficient, so black smoke is generated and exhaust gas performance deteriorates.
Therefore, the EGR can be performed only while the air-fuel ratio of the combustion chamber is kept thin by the intake air supercharged from one side of the intake passage.

【０００９】ところが、エンジンの高負荷／高回転時に
おいて最大に取り込まれる新気の吸気量は、片方の吸気
通路の大きさで決まるので、ＥＧＲは燃焼室が理論空燃
比となる高エンジントルク／高エンジン回転数域の途中
までしか続けられない。However, the maximum intake amount of fresh air taken in at high engine load / high engine speed is determined by the size of one intake passage, so EGR is a high engine torque / fuel ratio in which the combustion chamber has a theoretical air-fuel ratio. It can only be continued halfway through the high engine speed range.

【００１０】しかも、ＥＧＲを無理やり続けるとエンジ
ンの排ガス性能が悪化する。そうかといって、理論空燃
比となる地点から、閉じていた吸気通路の開閉弁を開に
すると、吸気圧力が過給によって排気ガスの圧力以上に
高くなっているからＥＧＲが行えない。Moreover, if EGR is continued forcibly, the exhaust gas performance of the engine deteriorates. On the other hand, if the opening / closing valve of the closed intake passage is opened from the point where the stoichiometric air-fuel ratio is reached, EGR cannot be performed because the intake pressure becomes higher than the exhaust gas pressure due to supercharging.

【００１１】このため、過給機付エンジンは、高エンジ
ントルク／高エンジン回転域でＥＧＲ効果を十分に発揮
させることが難しく、これを改善したＥＧＲ装置が望ま
れている。For this reason, it is difficult for the supercharged engine to sufficiently exert the EGR effect in the high engine torque / high engine rotation range, and an EGR device that improves this is desired.

【００１２】本発明は上記事情に着目してなされたもの
で、その目的とするところは、ＥＧＲが行えるエンジン
の高負荷／高速の運転領域の拡大が図れる過給機付エン
ジンの排気ガス還流装置を提供することにある。The present invention has been made in view of the above circumstances, and an object thereof is to provide an exhaust gas recirculation system for an engine with a supercharger capable of expanding the high load / high speed operation range of the engine capable of performing EGR. To provide.

【００１３】[0013]

【課題を解決するための手段】上記目的を達成するため
に請求項１に記載の排気ガス還流装置では、過給機から
の過給吸気を第１吸気通路を通じてエンジンの燃焼室へ
導くとともに過給機を通らずに取り込まれた吸気を第２
吸気通路を通じてエンジンの燃焼室へ導き、かつ第２吸
気通路を通じてエンジンの排気ガスの一部を燃焼室へ導
入させる第１モードを有する過給機付エンジンの排気ガ
ス還流装置において、第１吸気通路および第２吸気通路
の双方を通じて過給吸気を燃焼室へ導くように流れを切
換えるとともに該第２吸気通路を通じてエンジンの排気
ガスの一部を燃焼室へ導入させる第２モードを形成する
手段を設け、過給機の過給圧に応じて、該過給圧が高い
ときは、第１モードに切換え、該過給圧が低いときは第
２モードに切換える手段を設けた。In the exhaust gas recirculation device according to claim 1 in order to achieve the above object, according to an aspect of the over-guides to the combustion chamber of the engine through the first intake passage turbocharged from the supercharger Second intake air taken without passing through the feeder
It led to the combustion chamber of the engine through the intake passage, and exhaust gas of an engine with a supercharger having a first mode for introducing a part of the exhaust gas from the engine into the combustion chamber through the second intake passage
In the recirculation device, a first intake passage and a second intake passage
The flow is cut so that supercharged intake air is guided to the combustion chamber through both
And the engine exhaust through the second intake passage
Form a second mode that introduces some of the gas into the combustion chamber
A means is provided, and the supercharging pressure is high according to the supercharging pressure of the supercharger.
When the boost pressure is low, switch to the first mode.
A means for switching to two modes is provided .

【００１４】これにより、過給圧の上昇に関係なく、Ｅ
ＧＲが続けられる。As a result , regardless of the increase in boost pressure, E
GR continues.

【００１５】したがって、ＥＧＲを行なえるエンジン運
転領域は、高エンジントルク／高エンジン回転数側に拡
がる。しかも、過給圧が低いエンジンの運転領域でのＥ
ＧＲ効果が促進されるから、エンジン運転領域の広範囲
に渡り大量のＥＧＲが行なえる。 [0015] Thus, the engine operating region capable of EGR may expand <br/> is that the high engine torque / high engine speed side. Moreover, E in the operating range of the engine with low boost pressure
Since the GR effect is promoted, the engine operating range is wide
A large amount of EGR can be performed over a long period.

【００１６】請求項２に記載の排気ガス還流装置は、高
いＥＧＲ率が確保されるよう、さらに、第１吸気通路を
通じて過給吸気を燃焼室へ導くとともに第２吸気通路を
通じてエンジンの排気ガスだけを燃焼室へ導入させる第
３モードを有し、該第３モードが、高いＥＧＲ率を必要
とするときに切換わるようにした。In the exhaust gas recirculation system according to the second aspect, the supercharged intake air is guided to the combustion chamber through the first intake passage and only the exhaust gas of the engine is supplied through the second intake passage so as to ensure a high EGR rate. Is introduced into the combustion chamber, and the third mode is switched when a high EGR rate is required.

【００１７】[0017]

【発明の実施の形態】以下、本発明を図１ないし図６に
示す一実施形態にもとづいて説明する。図１は、本発明
の排気ガス還流装置を適用した、車両に搭載される過給
機付の直噴式（直接噴射式）ディーゼルエンジン周りの
構造を示し、図中１は車両のエンジンルーム（図示しな
い）に収容されるエンジン本体である。BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on an embodiment shown in FIGS. FIG. 1 shows a structure around a direct injection type (direct injection type) diesel engine with a supercharger mounted on a vehicle, to which an exhaust gas recirculation system of the present invention is applied, and in the figure, 1 is an engine room of the vehicle (shown in the figure. It is the main body of the engine that is housed in.

【００１８】エンジン本体１は、周知のようにシリンダ
ブロック２とシリンダヘッド３とで囲まれるシリンダ４
内にピストン５を往復可能に嵌挿して構成され、シリン
ダヘッド３のシリンダ毎に組み付けた例えば２個づつの
吸気弁６ａ，６ｂおよび排気弁７ａ，７ｂ、さらにはシ
リンダ毎に組み付けた燃料噴射ノズル（図示しない）に
より、燃焼室８内で吸入工程、圧縮工程、燃料噴射工
程、膨張工程、排気工程を繰り返して、クランクシャフ
ト（図示しない）から軸出力が発生されるようにしてあ
る。なお、吸／排気弁６ａ，６ｂ，７ａ，７ｂは、シリ
ンダヘッド３に各々弁毎に２個づつ独立に形成してある
吸気ポート９ａ，９ｂおよび排気ポート１０ａ，１０ｂ
に取り付けてある。As is well known, the engine body 1 includes a cylinder 4 surrounded by a cylinder block 2 and a cylinder head 3.
For example, two intake valves 6a and 6b and two exhaust valves 7a and 7b each having a piston 5 reciprocally inserted therein and assembled for each cylinder of the cylinder head 3, and further a fuel injection nozzle assembled for each cylinder. By (not shown), the intake process, the compression process, the fuel injection process, the expansion process, and the exhaust process are repeated in the combustion chamber 8 to generate a shaft output from a crankshaft (not shown). It should be noted that the intake / exhaust valves 6a, 6b, 7a, 7b are independently formed in the cylinder head 3 such that two valves are provided for each of the intake ports 9a, 9b and exhaust ports 10a, 10b.
It is attached to.

【００１９】１１は、エンジン本体１と共にエンジンル
ームに収容される過給機、例えばターボチャージャーで
ある。ターボチャージャー１１は、周知のように一本の
シャフト１２の両端に排気ガスタービン部１３とエアコ
ンプレッサ部１４とを組み付けて構成される。そして、
排気ガスタービン部１３は、各排気ポート端から延びる
排気通路１５に介装され、排気ポート１０ａ，１０ｂか
ら排出される排気ガスの熱エネルギーで駆動されるよう
にしてある。またエアコンプレッサ部１３は、吸気ポー
ト９ａ，９ｂの一方、例えば吸気ポート９ａとエアクリ
ーナー１６との間に接続される吸気通路１７（吸気ポー
ト９ａと共に第１吸気通路を構成）の途中に介装され、
エアコンプレッサ部１４で行われる圧送によって、エア
クリーナー１６から取り込んだ吸気を圧力を高めて吸気
ポート９ａから燃焼室８へ過給できるようにしている。
なお、吸気通路１７の途中にはインタクーラー１８が介
装してある。Reference numeral 11 is a supercharger, for example, a turbocharger, which is housed in the engine room together with the engine body 1. As is well known, the turbocharger 11 is constructed by assembling an exhaust gas turbine section 13 and an air compressor section 14 at both ends of a single shaft 12. And
The exhaust gas turbine section 13 is interposed in an exhaust passage 15 extending from each exhaust port end, and is driven by the thermal energy of the exhaust gas discharged from the exhaust ports 10a and 10b. The air compressor unit 13 is interposed in one of the intake ports 9a and 9b, for example, in the middle of an intake passage 17 (which constitutes the first intake passage together with the intake port 9a) connected between the intake port 9a and the air cleaner 16. Is
The pressure of the intake air taken in from the air cleaner 16 is increased by the pressure feeding performed by the air compressor unit 14 so that the intake air can be supercharged from the intake port 9a to the combustion chamber 8.
An intercooler 18 is provided in the middle of the intake passage 17.

【００２０】残る他方の吸気ポート９ｂは、吸気通路１
７とは別の独立した吸気通路１９（吸気ポート９ｂと共
に第２吸気通路を構成）で、エアクリーナー１６と接続
されていて、ターボチャージャー１１を通らずに吸気を
燃焼室８へ供給できるようにしてある。The other remaining intake port 9b is connected to the intake passage 1
In another independent intake passage 19 and 7 (constituting the second intake passage with the intake port 9 b), be connected to the air cleaner 16, so that it can supply the intake air to the combustion chamber 8 without passing through the turbocharger 11 I am doing it.

【００２１】この吸気通路１９の下流側には、排気通路
１５の途中から分岐したＥＧＲ通路２０の出口が接続さ
れている。またこのＥＧＲ通路２０には、同通路２０を
開閉するＥＧＲ弁２１が介装されていて、エンジンから
排出された排気ガスの一部を吸気ポート９ｂから燃焼室
８へ導入できる構造にしてある。At the downstream side of the intake passage 19, an outlet of an EGR passage 20 branched from the middle of the exhaust passage 15 is connected. An EGR valve 21 that opens and closes the EGR passage 20 is interposed in the EGR passage 20 so that a part of the exhaust gas discharged from the engine can be introduced into the combustion chamber 8 from the intake port 9b.

【００２２】ＥＧＲ通路２０の出口から上流側の吸気通
路１９は、例えば開度が可変可能な開閉弁で構成される
バイパス弁２２が介装されたバイパス通路２３を介し
て、吸気通路１７のインタクーラ１８から上流側の部分
に接続してある。またバイパス通路２３の接続部から上
流側の吸気通路１９には、同通路１９を開閉する開閉弁
２４が介装され、バイパス弁２２と開閉弁２４とで行わ
れる流路制御によって、過給した吸気を吸気ポート９ａ
と吸気ポート９ｂの双方から燃焼室８へ導く流れのモー
ド、ＥＧＲ通路２０からの排気ガスをそのまま吸気ポー
ト９ｂから燃焼室８へ導入させる流れのモードに切り換
えられるようにしてある（流路制御手段）。The intake passage 19 on the upstream side from the outlet of the EGR passage 20 has an intercooler of the intake passage 17 via a bypass passage 23 in which a bypass valve 22 constituted by an opening / closing valve whose opening degree is variable is provided. 18 is connected to the upstream side portion. An on-off valve 24 that opens and closes the intake passage 19 upstream from the connection portion of the bypass passage 23 is provided, and supercharging is performed by the flow passage control performed by the bypass valve 22 and the on-off valve 24. Intake the intake port 9a
And a flow mode in which exhaust gas from the EGR passage 20 is introduced into the combustion chamber 8 from the intake port 9b as it is (flow passage control means). ).

【００２３】一方、２５は例えばマイクロコンピュータ
から構成されたＥＣＵである。このＥＣＵ２５には、例
えば予め設定された噴射時期，燃料噴射量のマップか
ら、エンジンの運転状態（エンジン回転数、アクセル開
度）に応じた噴射時期，燃料噴射量を決定して、燃料噴
射弁（図示しない）を駆動して噴射ノズルから、エンジ
ンの運転に応じた燃料を噴射させる機能が設定されてい
る。On the other hand, 25 is an ECU composed of, for example, a microcomputer. The ECU 25 determines the injection timing and the fuel injection amount according to the operating state of the engine (engine speed, accelerator opening) from a map of preset injection timing and fuel injection amount, and determines the fuel injection valve. A function of driving (not shown) to inject fuel according to the operation of the engine from the injection nozzle is set.

【００２４】またＥＣＵ２５には、エンジンの運転状
態、さらには過給吸気の圧力を検知する給気圧センサ２
６、排気ガスタービン部１３のタービン入口の圧力（排
気圧力）を検知するタービン入口圧センサ２７からの出
力にしたがって、排気還流装置を制御する機能が設定さ
れている。Further, the ECU 25 is provided with an air pressure sensor 2 for detecting the operating state of the engine and further the pressure of the supercharged intake air.
6. The function of controlling the exhaust gas recirculation device is set according to the output from the turbine inlet pressure sensor 27 that detects the pressure (exhaust pressure) at the turbine inlet of the exhaust gas turbine unit 13.

【００２５】具体的には、例えばＥＣＵ２５にはつぎの
ような機能が設定されている。すなわち、ＥＧＲを行わ
ない全負荷時のエンジン運転と、それ以外のＥＧＲを行
うエンジン運転とを判定する機能。Specifically, the following functions are set in the ECU 25, for example. That is, a function of determining the engine operation at full load without EGR and the engine operation other than EGR.

【００２６】ＥＧＲをしない全負荷運転のときは、各Ｅ
ＧＲ弁２１を閉止したまま、過給された吸気だけを吸気
ポート９ａ，９ｂの双方から燃焼室８へ導くモード（開
閉弁２４：閉、バイパス弁２２：開）にする機能。At full load operation without EGR, each E
With the GR valve 21 kept closed, a function of bringing only the supercharged intake air into the combustion chamber 8 from both the intake ports 9a and 9b (open / close valve 24: closed, bypass valve 22: open).

【００２７】ＥＧＲを行う運転のときで、過給圧力Ｐｂ
がタービン入口圧力Ｐｔｉより低いときは、過給吸気を
吸気ポート９ａ，９ｂの双方から燃焼室８へ導き、片方
の吸気ポート９ｂを通じてＥＧＲ通路２０から排気ガス
を燃焼室８へ還流させるモードにする機能。During an EGR operation, the supercharging pressure Pb
Is lower than the turbine inlet pressure Pti, the supercharged intake air is introduced into the combustion chamber 8 from both the intake ports 9a and 9b, and the exhaust gas is returned from the EGR passage 20 to the combustion chamber 8 through one intake port 9b. function.

【００２８】ＥＧＲを行う運転のときで、過給圧力Ｐｂ
がタービン入口圧力Ｐｔｉより高いときは、過給吸気を
吸気通路１７を経て吸気ポート９ａから燃焼室８へ導
き、またこれとは独立して無過給の吸気を吸気通路１９
を経て吸気ポート９ｂから燃焼室８へ導き、この無過給
の吸気が流れる吸気ポート９ｂを通じてＥＧＲ通路２０
から排気ガスを燃焼室８へ還流させるモードにする機
能。このとき、空気量が不足する部分負荷域であれば、
バイパス弁２２を開側に開度を調節して、吸気ポート９
ｂ側を若干、過給して空気量を増すモードにする機能。During the operation for performing EGR, the supercharging pressure Pb
Is higher than the turbine inlet pressure Pti, the supercharged intake air is guided from the intake port 9a to the combustion chamber 8 through the intake passage 17, and independently of this, the non-supercharged intake air is introduced into the intake passage 19
Through the intake port 9b to the combustion chamber 8, and the EGR passage 20 is introduced through the intake port 9b through which the unsupercharged intake air flows.
From the exhaust gas to the combustion chamber 8. At this time, if the partial load range where the air amount is insufficient,
By adjusting the opening of the bypass valve 22 to the open side, the intake port 9
A function to slightly supercharge the b side to increase the amount of air.

【００２９】この他、高いＥＧＲ率を必要とするとき
は、過給吸気を吸気通路１７，吸気ポート９ａを通じて
燃焼室８へ導くと共に、吸気ポート９ｂと直結したＥＧ
Ｒ通路２０から排気ガスを燃焼室８へ還流させるモード
にする機能。In addition, when a high EGR rate is required, supercharged intake air is introduced into the combustion chamber 8 through the intake passage 17 and the intake port 9a, and the EG connected directly to the intake port 9b.
A function of setting a mode in which exhaust gas is recirculated from the R passage 20 to the combustion chamber 8.

【００３０】こうした制御によって、過給機付ディーゼ
ルエンジンのＥＧＲが行える領域を拡げたり、大量のＥ
ＧＲが行えるようにしている。すなわち、排気ガス還流
装置の作用について説明すれば、今、ディーゼルエンジ
ンが全負荷で運転されたとする。このとき、ＥＣＵ２５
は、ＥＧＲが必要でないと判定して、「全負荷」のモー
ドにしたがい図２に示されるように開閉弁２４を閉、バ
イパス弁２２を開、ＥＧＲ弁２１を閉にする。With such control, the area where the EGR of the diesel engine with a supercharger can be performed is expanded, and a large amount of E
I am trying to do GR. That is, to explain the operation of the exhaust gas recirculation device, it is assumed that the diesel engine is now operating at full load. At this time, the ECU 25
Determines that EGR is not required and closes the on-off valve 24, opens the bypass valve 22 and closes the EGR valve 21 according to the "full load" mode, as shown in FIG.

【００３１】すると、図２中の太線に示されるようにタ
ーボチャージャー１１で過給された吸気は、吸気ポート
９ａから燃焼室８へ供給されると同時に、バイパス弁２
２を通じて吸気ポート９ｂから燃焼室８へ供給される。Then, as shown by the thick line in FIG. 2, the intake air supercharged by the turbocharger 11 is supplied from the intake port 9a to the combustion chamber 8 and at the same time the bypass valve 2
2 is supplied to the combustion chamber 8 from the intake port 9b.

【００３２】これにより、吸気ポート９ａ，９ｂの双方
から吸気を燃焼室８に過給して、エンジン出力を高めた
ディーゼルエンジンの運転が行われる（ＥＧＲ無し）。
続いて、ディーゼルエンジンの運転が全負荷運転から、
過給圧Ｐｂがタービン入口圧Ｐｔｉより低くなる運転に
なったとする。As a result, intake air from both the intake ports 9a and 9b is supercharged into the combustion chamber 8 to operate the diesel engine with increased engine output (no EGR).
Then, the operation of the diesel engine from full load operation,
It is assumed that the supercharging pressure Pb is lower than the turbine inlet pressure Pti.

【００３３】このときには、ＥＣＵ２５の指令により、
「過給圧低」のモードにしたがい、ＥＧＲ弁２１は開に
変わる。すると、図３中の太線に示されるようにＥＧＲ
通路２０からの排気ガスが、低過給圧の新気に押し込ま
れるようにして、吸気通路１９、吸気ポート９ｂからエ
ンジンの吸気側に戻る。At this time, according to a command from the ECU 25,
According to the "supercharging pressure low" mode, the EGR valve 21 changes to open. Then, as shown by the thick line in FIG.
The exhaust gas from the passage 20 is pushed into the fresh air having a low boost pressure, and returns from the intake passage 19 and the intake port 9b to the intake side of the engine.

【００３４】これにより、ＥＧＲ効果を発揮させたエン
ジン運転が行われる。続いて、ディーゼルエンジンが高
負荷／高回転域の運転になり、タービン入口圧Ｐｔｉよ
り過給圧Ｐｂが高くなったとする。As a result, the engine is operated with the EGR effect. Subsequently, it is assumed that the diesel engine is operated in a high load / high speed range and the supercharging pressure Pb is higher than the turbine inlet pressure Pti.

【００３５】すると、ＥＣＵ２５の指令により、「過給
圧高」のモードにしたがい、バイパス弁２２は閉、開閉
弁２４は開に変わる。これにより、図４中の太線に示さ
れるようにターボチャージャー１１で過給された吸気
は、独立した通路となる吸気通路１７、吸気ポート９ａ
を通って燃焼室８へ供給される。また無過給の吸気も、
独立した通路となる吸気通路１９、吸気ポート９ｂを通
って燃焼室８へ供給される。Then, according to the command from the ECU 25, the bypass valve 22 is closed and the on-off valve 24 is opened according to the "high boost pressure" mode. As a result, the intake air supercharged by the turbocharger 11 becomes an independent passage as shown by the thick line in FIG.
Is supplied to the combustion chamber 8. In addition, unsupercharged intake
It is supplied to the combustion chamber 8 through an intake passage 19 and an intake port 9b which are independent passages.

【００３６】すると、ＥＧＲ通路２０からの排気ガス
は、大気圧の新気に押し込まれるようにして、吸気通路
１９，吸気ポート９ｂを経てエンジンの吸気側に戻り、
ＥＧＲ効果を発揮する。Then, the exhaust gas from the EGR passage 20 is pushed into the fresh air at atmospheric pressure and returns to the intake side of the engine via the intake passage 19 and the intake port 9b.
Exhibits the EGR effect.

【００３７】これにより、ＥＧＲ通路２０からの排気ガ
スは、常に無過給状態の新気と共に、エンジンの吸入側
へ還流されるので、過給圧の上昇に関係なく、ＥＧＲが
続けられる。As a result, the exhaust gas from the EGR passage 20 is always recirculated to the intake side of the engine together with the fresh air in the non-supercharged state, so that the EGR is continued regardless of the increase of the supercharging pressure.

【００３８】しかも、このＥＧＲは、無過給状態の新気
流入により、燃焼室８の空気過剰率を増しながら行われ
る。それ故、本発明の排気ガス還流装置だと、ＥＧＲを
行えるエンジンの運転領域は、吸気通路１９，吸気ポー
ト９ｂから燃焼室８へ供給される新気の増加分、すなわ
ち吸気量の増加で空気過剰率が増える分、図６に示され
る線図のように高エンジントルク／高エンジン回転数側
に拡大できる。しかも、このとき空気不足が生じたなら
ば（部分負荷域など）、閉止していたバイパス弁２２を
若干、開いて、吸気ポート９ｂ側を若干、過給すれば、
空気不足が解消されるので、一層、高エンジントルク／
高エンジン回転数寄りでＥＧＲを続けることができる。Moreover, this EGR is performed while increasing the excess air ratio of the combustion chamber 8 by the inflow of fresh air in the non-supercharged state. Therefore, with the exhaust gas recirculation device of the present invention, the operating range of the engine capable of performing EGR is that the amount of fresh air supplied from the intake passage 19 and the intake port 9b to the combustion chamber 8 increases, that is, the amount of intake air increases. As the excess rate increases, it can be expanded to the high engine torque / high engine speed side as shown in the diagram of FIG. Moreover, if an air shortage occurs at this time (partial load range, etc.), the bypass valve 22 that has been closed is slightly opened, and the intake port 9b side is slightly supercharged.
Higher engine torque /
EGR can be continued near the high engine speed.

【００３９】また排気ガス還流装置は、これに加え過給
圧が低いときには吸気ポート９ａ，９ｂの双方から燃焼
室８へ供給される過給吸気と共に排気ガスを還流させた
ので、過給圧が低いエンジンの運転領域でも大量のＥＧ
Ｒが行え、エンジン運転領域の全体に渡り、高いＥＧＲ
効果が確保できる。In addition to this, when the supercharging pressure is low, the exhaust gas recirculating device recirculates the exhaust gas together with the supercharging intake air supplied to the combustion chamber 8 from both the intake ports 9a and 9b. Large amount of EG even in low engine operating range
R can be performed, and EGR is high throughout the engine operating range.
The effect can be secured.

【００４０】しかも、排気ガス還流装置は、高ＥＧＲ率
が必要な運転領域のときは、図５に示されるように無過
給新気の供給を行う経路を遮断して、ＥＧＲ通路２０の
排気ガスをそのままエンジンの吸気側に戻しているの
で、高いＥＧＲ率も確保できる。In addition, the exhaust gas recirculation system shuts off the path for supplying unsupercharged fresh air as shown in FIG. 5 in the operating region where a high EGR rate is required, so that the exhaust gas in the EGR passage 20 is exhausted. Since the gas is returned to the intake side of the engine as it is, a high EGR rate can be secured.

【００４１】そのうえ、こうした効果をもたらす還流構
造は、無過給状態の新気に排気ガスを導入する構造に、
吸気通路１７，１９の相互間をＥＧＲ通路２０の上流側
で開閉するバイパス弁２２、バイパス弁２２の下流側で
吸気通路１９を開閉する開閉弁２４を組み合わせただけ
なので、簡単な構造ですむ。In addition, the recirculation structure that brings about such effects is a structure in which exhaust gas is introduced into fresh air without supercharging.
A simple structure is achieved by only combining a bypass valve 22 that opens and closes the intake passages 17 and 19 on the upstream side of the EGR passage 20 and an open / close valve 24 that opens and closes the intake passage 19 on the downstream side of the bypass valve 22.

【００４２】なお、一実施形態は、ターボチャージャー
で過給するエンジンの排気ガス還流装置を例に挙げた
が、むろんターボチャージャー以外の過給機で過給する
エンジンの排気ガス還流装置に本発明を適用してもよ
い。In the embodiment, the exhaust gas recirculation system for the engine supercharged by the turbocharger is taken as an example, but the exhaust gas recirculation system for the engine supercharged by the supercharger other than the turbocharger is of course applicable to the present invention. May be applied.

【００４３】[0043]

【発明の効果】以上説明したように請求項１に記載の発
明によれば、過給圧の上昇に関係なくＥＧＲが続けられ
るので、ＥＧＲを行なえるエンジンの運転領域は、高エ
ンジントルク／高エンジン回転数側に拡大できる。しか
も、過給圧が低いエンジンの運転領域でのＥＧＲ効果を
促進させることができ、エンジン運転領域の広範囲に渡
り大量のＥＧＲが行なえる。As described above, according to the invention of claim 1, the EGR is continued regardless of the increase of the supercharging pressure, so that the operating range of the engine capable of performing the EGR is high engine torque / high engine torque. It can be expanded to the engine speed side. Moreover, the EGR effect can be promoted in the engine operating region where the boost pressure is low, and a large amount of EGR can be performed over a wide range of the engine operating region.

【００４４】[0044]

【００４５】請求項２に記載の発明によれば、高いＥＧ
Ｒ率の確保が可能となる。According to the invention of claim 2, high EG
It is possible to secure the R rate .

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の一実施形態の排気ガス還流装置の構成
を説明するための図。FIG. 1 is a diagram for explaining the configuration of an exhaust gas recirculation device according to an embodiment of the present invention.

【図２】ＥＧＲがないエンジン運転のときの吸気の流れ
を説明するための図。FIG. 2 is a diagram for explaining a flow of intake air during engine operation without EGR.

【図３】過給圧がタービン入口圧より低いときのＥＧＲ
を説明するための図。FIG. 3 EGR when the boost pressure is lower than the turbine inlet pressure
FIG.

【図４】過給圧がタービン入口より高いときのＥＧＲを
説明するための図。FIG. 4 is a diagram for explaining EGR when the boost pressure is higher than the turbine inlet.

【図５】高いＥＧＲ率でＥＧＲを行ったときを説明する
ための図。FIG. 5 is a diagram for explaining a case where EGR is performed at a high EGR rate.

【図６】エンジン運転領域の高エンジントルク／高エン
ジン回転側のＥＧＲが実現されることを説明するための
線図。FIG. 6 is a diagram for explaining that high engine torque / high engine rotation side EGR in an engine operating region is realized.

【符号の説明】[Explanation of symbols]

８…燃焼室 ９ａ，１７…吸気ポート，吸気通路（第１吸気通路） ９ｂ，１９…吸気ポート，吸気通路（第２吸気通路） ２０…ＥＧＲ通路 ２１…ＥＧＲ弁 ２２…バイパス弁 ２４…開閉弁。 8 ... Combustion chamber 9a, 17 ... Intake port, intake passage (first intake passage) 9b, 19 ... Intake port, intake passage (second intake passage) 20 ... EGR passage 21 ... EGR valve 22 ... Bypass valve 24 ... Open / close valve.

フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) F02M 25/07 550 F02M 25/07 570 F02B 37/00 302 F02B 37/16 Front page continued (58) Fields surveyed (Int.Cl. 7 , DB name) F02M 25/07 550 F02M 25/07 570 F02B 37/00 302 F02B 37/16

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】 過給機を通して取り込まれた過給吸気を
第１吸気通路を通じてエンジンの燃焼室へ導くとともに
前記過給機を通らずに取り込まれた吸気を第２吸気通路
を通じて前記エンジンの燃焼室へ導き、かつ前記第２吸
気通路を通じて前記エンジンの排気ガスの一部を前記燃
焼室へ導入させる第１モードを有する過給機付エンジン
の排気ガス還流装置において、 前記第１吸気通路および前記第２吸気通路の双方を通じ
て過給吸気を前記燃焼室へ導くように流れを切換えると
ともに該第２吸気通路を通じて前記エンジンの排気ガス
の一部を前記燃焼室へ導入させる第２モードを形成する
手段を設け、 前記過給機の過給圧に応じて、該過給圧が高いときは、
前記第１モードに切換え、該過給圧が低いときは前記第
２モードに切換える手段を設けてなることを特徴とする
過給機付エンジンの排気ガス還流装置。1. A supercharged intake air taken in through a supercharger is introduced into a combustion chamber of an engine through a first intake passage, and an intake air taken in without passing through the supercharger is burned in the engine through a second intake passage. An exhaust gas recirculation system for a supercharged engine having a first mode in which a portion of exhaust gas of the engine is introduced into the combustion chamber through the second intake passage, Means for forming a second mode in which a flow is switched so that supercharged intake air is guided to the combustion chamber through both of the second intake passages, and a part of the exhaust gas of the engine is introduced into the combustion chamber through the second intake passage. According to the supercharging pressure of the supercharger, when the supercharging pressure is high,
An exhaust gas recirculation device for an engine with a supercharger, comprising means for switching to the first mode and for switching to the second mode when the supercharging pressure is low. 【請求項２】 さらに、前記第１吸気通路を通じて過給
吸気を前記燃焼室へ導くとともに前記第２吸気通路を通
じて前記エンジンの排気ガスだけを前記燃焼室へ導入さ
せる第３モードを有し、 該第３モードが、高いＥＧＲ率を必要とするときに切換
わるようにしてなることを特徴とする請求項１に記載の
過給機付エンジンの排気ガス還流装置。2. A third mode in which supercharged intake air is introduced into the combustion chamber through the first intake passage and only exhaust gas of the engine is introduced into the combustion chamber through the second intake passage, The exhaust gas recirculation device for a supercharged engine according to claim 1, wherein the third mode is switched when a high EGR rate is required.
JP35129797A 1997-12-19 1997-12-19 Exhaust gas recirculation system for turbocharged engine Expired - Fee Related JP3456133B2 (en)

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JP35129797A JP3456133B2 (en) 1997-12-19 1997-12-19 Exhaust gas recirculation system for turbocharged engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP35129797A JP3456133B2 (en) 1997-12-19 1997-12-19 Exhaust gas recirculation system for turbocharged engine

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JPH11182358A JPH11182358A (en) 1999-07-06
JP3456133B2 true JP3456133B2 (en) 2003-10-14

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Publication number Priority date Publication date Assignee Title
JP4526395B2 (en) 2004-02-25 2010-08-18 臼井国際産業株式会社 Internal combustion engine supercharging system
JP6032802B2 (en) * 2012-11-02 2016-11-30 日野自動車株式会社 EGR device

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