JP6675781B2 - Supercharged engine - Google Patents

Supercharged engine Download PDF

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JP6675781B2
JP6675781B2 JP2016028593A JP2016028593A JP6675781B2 JP 6675781 B2 JP6675781 B2 JP 6675781B2 JP 2016028593 A JP2016028593 A JP 2016028593A JP 2016028593 A JP2016028593 A JP 2016028593A JP 6675781 B2 JP6675781 B2 JP 6675781B2
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exhaust
path
turbine
exhaust gas
exhaust manifold
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陽 目黒
陽 目黒
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Hino Motors Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Description

本発明は、タービンより上流側の排気系から排気ガスの一部を抜き出してコンプレッサより下流側の吸気系へ再循環するＥＧＲ装置を備えた過給エンジンに関するものである。 The present invention relates to a supercharged engine including an EGR device that extracts a part of exhaust gas from an exhaust system upstream of a turbine and recirculates the exhaust gas to an intake system downstream of a compressor.

従来、排気ガスで駆動されるタービンによりコンプレッサを駆動して正規の量以上の吸気を取り込むことで出力の大幅な向上を図り得るようにしたターボチャージャ付き過給エンジンが知られており、この種の過給エンジンにあっては、前記タービンより上流側の排気系から排気ガスの一部を抜き出して前記コンプレッサより下流側の吸気系へ再循環し、その吸気系に戻された排気ガスで各気筒内での燃料の燃焼を抑制して燃焼温度を下げることによりＮＯxの発生を低減するＥＧＲ（Exhaust Gas Recirculation）装置を備えたものもある。   Conventionally, there has been known a turbocharged engine with a turbocharger in which a compressor is driven by a turbine driven by exhaust gas to take in intake air in an amount equal to or more than a regular amount so that the output can be significantly improved. In the supercharged engine, a part of the exhaust gas is extracted from the exhaust system on the upstream side of the turbine and recirculated to the intake system on the downstream side of the compressor, and each of the exhaust gases is returned to the intake system. Some include an EGR (Exhaust Gas Recirculation) device that suppresses the combustion of fuel in a cylinder and lowers the combustion temperature to reduce the generation of NOx.

ただし、前述の如き過給エンジンの場合、過給効率の高い低速高負荷領域にてターボチャージャによる過給圧が排気圧より高くなってしまう領域が生じる結果、このような低速高負荷領域について何も対策を講じなければ、排気側から吸気側への排気ガスの再循環を行うことができなくなってしまう。   However, in the case of the above-described supercharged engine, there is a region where the supercharging pressure by the turbocharger becomes higher than the exhaust pressure in a low-speed high-load region where the supercharging efficiency is high. If no countermeasures are taken, the exhaust gas cannot be recirculated from the exhaust side to the intake side.

このため、大型運搬車両等における大量の排気ガス再循環を実施する必要のある過給エンジンにおいては、タービン側のノズル開度を任意に変更することが可能な容量可変式のターボチャージャ（バリアブルジオメトリーターボチャージャと一般的に呼称されているもの）を採用し、必要に応じタービン側のノズル開度を小さく絞り込んで排気ガスの通過抵抗を増やし、これにより排気マニホールドの圧力を高めて吸気側と排気側との圧力差を確保するようにしている。   For this reason, in a supercharged engine that needs to carry out a large amount of exhaust gas recirculation in a large transport vehicle or the like, a variable-capacity type turbocharger (Variable Geo) that can arbitrarily change the nozzle opening on the turbine side is used. (Commonly referred to as a metrology turbocharger), and if necessary, narrow the nozzle opening on the turbine side to increase the exhaust gas passage resistance, thereby increasing the exhaust manifold pressure and increasing the intake manifold pressure. A pressure difference with the exhaust side is ensured.

即ち、容量可変式のターボチャージャは、タービンの駆動力が弱いために空気を取り込み難い低速運転領域と、タービンが回りすぎて空気が過剰に取り込まれる虞れのある高速運転領域とでターボチャージャの容量を適宜に変更して低速重視の過給特性と高速重視の過給特性とを使い分けられるようにしたものであるが、これを低速高負荷領域における排気ガス再循環の対策として流用するようにしている。   That is, the variable-capacity turbocharger has a low-speed operation region in which it is difficult to take in air because the driving force of the turbine is weak, and a high-speed operation region in which there is a risk that excessive air may be taken in due to excessive rotation of the turbine. The capacity is appropriately changed so that the supercharging characteristic that emphasizes low speed and the supercharging characteristic that emphasizes high speed can be used properly, but this is used as a measure for exhaust gas recirculation in the low speed and high load region. ing.

ここで、低速高負荷領域での排気ガスの再循環を実現することだけを考えれば、これまでよりも容量の小さなターボチャージャを採用すれば済むことになるが、そのような単純な対策を講じたとしても、高速高負荷領域でのポンピングロスが増加して燃費の大幅な悪化を招いてしまうことが明らかであり、現実的な対策とは到底言えないものであることを付言しておく。   Here, considering only the realization of exhaust gas recirculation in the low-speed and high-load region, it would suffice to employ a turbocharger with a smaller capacity than before, but such simple measures were taken. Even so, it is clear that the pumping loss in the high-speed and high-load region increases, leading to a significant deterioration in fuel efficiency, and it should be noted that this is not a practical measure at all.

尚、この種の容量可変式のターボチャージャに関連する先行技術文献情報としては下記の特許文献１等がある。   As prior art document information related to this type of variable capacity turbocharger, there is the following Patent Document 1 or the like.

特開２００７−９２５５７号公報JP 2007-92557 A

しかしながら、可動部分の多い複雑な機構となる容量可変式のターボチャージャを採用した場合には、コストの大幅な高騰を招いてしまうことが避けられないという問題があり、また、作業現場等における厳しい使用環境下で高い作動信頼性を保ち続けることが難しい上、その修理や整備等に高い技術や専用部品が必要となって簡単に修理や整備等を行うことができないという問題もあったため、容量可変式のターボチャージャを採用しない対策が求められている。   However, when a variable-capacity turbocharger, which has a complicated mechanism with many movable parts, is employed, there is a problem that it is inevitable that the cost will increase significantly. It is difficult to maintain high operation reliability under the use environment, and there is a problem that repair and maintenance require high technology and dedicated parts, making it difficult to perform repair and maintenance easily. There is a need for measures that do not employ a variable turbocharger.

本発明は上述の実情に鑑みてなしたもので、容量可変式のターボチャージャを採用せずに低速高負荷領域での排気ガスの再循環を実現し且つ高速高負荷領域でのポンピングロスの増加を防ぐことを目的としている。   The present invention has been made in view of the above circumstances, and realizes exhaust gas recirculation in a low-speed and high-load region without employing a variable-capacity turbocharger and increases pumping loss in a high-speed and high-load region. The purpose is to prevent.

本発明は、排気ガスで駆動されるタービンによりコンプレッサを駆動して過給を行うターボチャージャを搭載し、前記タービンより上流側の排気系から排気ガスの一部を抜き出して前記コンプレッサより下流側の吸気系へ再循環するＥＧＲ装置を備えた過給エンジンであって、前記タービンのスクロールを小スクロールと大スクロールとに分割し、各気筒からの排気ガスを集めて前記タービンに導く排気マニホールドの連絡管部を区画壁により前記小スクロールに通じる第一経路と前記大スクロールに通じる第二経路とに分割し、前記区画壁の入側端にフラップ型の排気切替弁の基端部を傾動自在に枢支して、前記排気マニホールドを前記第一経路に通じる第一排気マニホールドと前記第二経路に通じる第二排気マニホールドとに開通閉止自在に分割し且つその開通時に前記排気切替弁により前記第二経路が閉止されるように構成し、前記ＥＧＲ装置の排気ガスの抜き出し位置を前記第一経路としたことを特徴とするものである。 The present invention is equipped with a turbocharger for supercharging by driving a compressor by a turbine driven by exhaust gas, extracting a part of the exhaust gas from an exhaust system on the upstream side of the turbine, and extracting a part of the exhaust gas on a downstream side of the compressor. A supercharged engine provided with an EGR device that recirculates to an intake system, wherein a turbine scroll is divided into a small scroll and a large scroll, and exhaust gas from each cylinder is collected and communicated with an exhaust manifold leading to the turbine. wherein the first path through the pipe section to the small scroll by partition walls is divided into a second path through the large scroll, a base end portion of the flap-type exhaust switching valve tiltably on entry end of the partition wall pivotally supported, opened closure itself to a second exhaust manifold communicating with the first exhaust manifold and said second path through said exhaust manifold to said first path The second path is configured to be closed by the exhaust switching valve split and its opening during, is characterized in that the withdrawal position of the exhaust gas in the EGR device and with the first path.

更に、本発明の過給エンジンを運転するにあたっては、低速高負荷領域での運転時に排気切替弁により第一排気マニホールドと第二排気マニホールドとを開通し且つ第二経路を閉止する一方、過給圧が排気圧より低い通常運転時には前記排気切替弁により第一排気マニホールドと第二排気マニホールドとを閉止し且つ第二経路を開通すると良い。 Furthermore, when operating the supercharged engine of the present invention, while closed and the second path opened and the first exhaust manifold and a second exhaust manifold by the exhaust switching valve during operation at low speed and high load region, the supercharging In a normal operation in which the pressure is lower than the exhaust pressure, the first exhaust manifold and the second exhaust manifold may be closed by the exhaust switching valve and the second path may be opened.

このようにすれば、低速高負荷領域での運転時に第一排気マニホールド及び第二排気マニホールドの両方の排気ガスを全て第一経路を通してタービンの小スクロールに導入し、タービンの容量を本来の容量よりも小さくした状態でターボチャージャの運転を行い、これにより過給圧を排気圧より低く抑えてＥＧＲ装置による排気ガスの再循環を支障なく実現することが可能となる。   With this configuration, during operation in the low-speed and high-load region, all exhaust gases of both the first exhaust manifold and the second exhaust manifold are introduced into the small scroll of the turbine through the first path, and the capacity of the turbine is reduced from the original capacity. The turbocharger is operated in a state in which the exhaust gas pressure is also reduced, so that the supercharging pressure can be suppressed to be lower than the exhaust pressure, and the recirculation of the exhaust gas by the EGR device can be realized without any trouble.

一方、過給圧が排気圧より低い通常運転時には排気切替弁により第一排気マニホールドと第二排気マニホールドの夫々の排気ガスを第一経路及び第二経路の夫々を通してタービンの小スクロール及び大スクロールの夫々に導入し、タービンの容量を本来の容量に戻した状態でターボチャージャの運転を行い、これにより高速高負荷領域でのポンピングロスの増加を招くことなくＥＧＲ装置による排気ガスの再循環を従前通り行うことが可能となる。 On the other hand, during normal operation in which the supercharging pressure is lower than the exhaust pressure , the exhaust gas of the first exhaust manifold and the second exhaust manifold is respectively discharged by the exhaust switching valve through the first path and the second path to the small scroll and the large scroll of the turbine. The turbocharger is operated in a state where the turbine capacity is returned to the original capacity by introducing each of the turbines, thereby enabling the exhaust gas recirculation by the EGR device to be performed without causing an increase in pumping loss in a high-speed and high-load region. It is possible to do as it is.

更に、本発明の過給エンジンを運転するにあたっては、加速時にも排気切替弁により第一排気マニホールドと第二排気マニホールドとを開通し且つ第二経路を閉止するようにしても良く、このようにすれば、加速時に前述と同様にタービンの容量を本来の容量よりも小さくした状態でターボチャージャの運転を行い、これにより加速時における応答性の大幅な向上を図ることが可能となる。   Further, in operating the supercharged engine of the present invention, the exhaust switching valve may open the first exhaust manifold and the second exhaust manifold and close the second path even during acceleration, as described above. Then, the turbocharger is operated in a state where the capacity of the turbine is smaller than the original capacity at the time of acceleration, as described above, whereby it is possible to greatly improve the responsiveness at the time of acceleration.

上記した本発明の過給エンジンによれば、下記の如き種々の優れた効果を奏し得る。 According to the supercharged engine of the present invention described above, various excellent effects as described below can be obtained.

（Ｉ）本発明の請求項１に記載の発明によれば、容量可変式のターボチャージャを採用せずに低速高負荷領域での排気ガスの再循環を実現し且つ高速高負荷領域でのポンピングロスの増加を防ぐことができるので、容量可変式のターボチャージャを採用した場合における諸問題を未然に回避することができると共に、全ての運転領域で良好に排気ガスを再循環してＮＯx低減性能の大幅な向上を図り且つ高速高負荷領域における燃費の悪化を防止することができる。 (I) According to the first aspect of the present invention, recirculation of exhaust gas in a low-speed high-load region is realized without employing a variable-capacity turbocharger, and pumping in a high-speed high-load region. Since the increase in loss can be prevented, various problems in the case of adopting a variable capacity turbocharger can be avoided beforehand, and the exhaust gas can be recirculated well in all operating regions to reduce NOx. Can be significantly improved, and deterioration of fuel efficiency in a high-speed high-load region can be prevented.

（ＩＩ）本発明の請求項１に記載の発明によれば、加速時にタービンの容量を本来の容量よりも小さくした状態でターボチャージャの運転を行い、タービンの容量を本来の容量で使用した場合よりも加速時の応答性を向上することができ、過渡応答性に優れた容量可変式のターボチャージャを採用しないことによる過渡応答性の低下を補完することができる。 (II) wherein according to the invention described in claim 1 of the present invention performs the operation of the turbocharger capacity turbine during acceleration in a state of being smaller than the original volume, if the capacity of the turbine was used in the original volume It is possible to improve the response at the time of acceleration, and to compensate for the decrease in the transient response caused by not using the variable capacity turbocharger having the excellent transient response.

本発明を実施する形態の一例を示す概略図である。It is a schematic diagram showing an example of an embodiment for carrying out the present invention. 図１の要部を拡大して示す説明図である。It is explanatory drawing which expands and shows the principal part of FIG. 図１の排気マニホールドの分割部分を開通した状態を示す概略図である。FIG. 2 is a schematic diagram showing a state where a divided portion of the exhaust manifold of FIG. 1 is opened. 図３の要部を拡大して示す説明図である。FIG. 4 is an explanatory diagram showing a main part of FIG. 3 in an enlarged manner. タービン容量と低速領域でのＥＧＲ率の関係を示すグラフである。5 is a graph showing a relationship between a turbine capacity and an EGR rate in a low speed region. タービン容量と高速領域でのポンピングロスの関係を示すグラフである。4 is a graph showing a relationship between a turbine capacity and a pumping loss in a high-speed region.

以下、本発明の実施の形態を図面を参照しつつ説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図１は本発明を実施する形態の一例を示すもので、ここに図示している過給エンジン１は、排気ガスＧで駆動されるタービン２ａによりコンプレッサ２ｂを駆動して過給を行うターボチャージャ２を搭載しており、図示しないエアクリーナから導いた吸気Ａを前記ターボチャージャ２のコンプレッサ２ｂへ送り、該コンプレッサ２ｂで加圧された吸気Ａをインタークーラ３へと送って冷却し、該インタークーラ３から更に吸気マニホールド４へと吸気Ａを導いて過給エンジン１の各気筒１ａ，１ｂ，１ｃ，１ｄ，１ｅ，１ｆに分配するようにしてある。   FIG. 1 shows an example of an embodiment of the present invention. A supercharged engine 1 shown here is a turbocharger that supercharges a compressor 2b driven by a turbine 2a driven by exhaust gas G. 2, the intake air A guided from an air cleaner (not shown) is sent to a compressor 2b of the turbocharger 2, and the intake air A pressurized by the compressor 2b is sent to an intercooler 3 for cooling. The intake air A is further guided from the intake manifold 3 to the intake manifold 4 and distributed to the cylinders 1a, 1b, 1c, 1d, 1e, 1f of the supercharged engine 1.

また、この過給エンジン１の各気筒１ａ，１ｂ，１ｃ，１ｄ，１ｅ，１ｆから排出された排気ガスＧを排気マニホールド５を介して前記ターボチャージャ２のタービン２ａへと送り、該タービン２ａを駆動した排気ガスＧを車外へ排出するようにしてあるが、前記タービン２ａのスクロールが小スクロールＴ1と大スクロールＴ2とに分割されている。 Further, exhaust gas G discharged from each of the cylinders 1a, 1b, 1c, 1d, 1e, 1f of the supercharged engine 1 is sent to a turbine 2a of the turbocharger 2 through an exhaust manifold 5, and the turbine 2a is It is so as to discharge the driven exhaust gases G to the outside of the vehicle, but the scroll of the turbine 2a is divided into small scroll T 1 and a large scroll T 2.

ここで、図２に図１の要部を拡大して示す如く、各気筒１ａ，１ｂ，１ｃ，１ｄ，１ｅ，１ｆからの排気ガスＧを集めて前記タービン２ａに導く排気マニホールド５の連絡管部６は、前記小スクロールＴ1に通じる第一経路Ｐ1と前記大スクロールＴ2に通じる第二経路Ｐ2とに分割されている。 Here, as shown in FIG. 2 in which a main part of FIG. 1 is enlarged, a connecting pipe of an exhaust manifold 5 that collects exhaust gas G from each cylinder 1a, 1b, 1c, 1d, 1e, 1f and guides the exhaust gas G to the turbine 2a. part 6 is the is divided into a first path P 1 leading to a small scroll T 1 and the second path P 2 leading the the large scroll T 2.

しかも、前記排気マニホールド５は、前記連絡管部６の入側に設けられた排気切替弁７により、気筒１ａ，１ｂ，１ｃを一組として前記第一経路Ｐ1に通じる第一排気マニホールドＭ1と、気筒１ｄ，１ｅ，１ｆを一組として前記第二経路Ｐ2に通じる第二排気マニホールドＭ2とに開通閉止自在に分割されており、その開通時には前記排気切替弁７により前記第二経路Ｐ2が閉止されるようになっている。 In addition, the exhaust manifold 5 is provided with a first exhaust manifold M 1 that communicates with the first path P 1 as a set of the cylinders 1 a, 1 b, 1 c by an exhaust switching valve 7 provided on the inlet side of the communication pipe portion 6. If, cylinder 1d, 1e, 1f are opened closed freely divided into the second exhaust manifold M 2 leading to the second path P 2 as a pair, the second path by the exhaust switching valve 7 at the time of its opening P 2 is adapted to be closed.

より具体的に説明すると、排気マニホールド５の連絡管部６にて第一経路Ｐ1と第二経路Ｐ2とを仕切る区画壁８の入側端にフラップ型の排気切替弁７の基端部が傾動自在に枢支され、該排気切替弁７の傾動位置により第一排気マニホールドＭ1と第二排気マニホールドＭ2との開通閉止及びその開通時における第二経路Ｐ2の閉止が成されるように構成されている。 To be more specific, the exhaust manifold in communication pipe portion 6 of the 5 and the first path P 1 base end portion of the exhaust switching valve 7 of the flap-type entry end of the second path P 2 and partition wall 8 partitioning the There is pivotally supported tiltably, a first exhaust manifold M 1 opened closure and closing of the second path P 2 at the opening time of the second exhaust manifold M 2 is performed by the tilted position of the exhaust switching valve 7 It is configured as follows.

ここで、図１及び図２は第一排気マニホールドＭ1と第二排気マニホールドＭ2との分割部分を排気切替弁７により閉止した状態を示しており、図３及び図４は第一排気マニホールドＭ1と第二排気マニホールドＭ2との分割部分を排気切替弁７により開通し且つ第二経路Ｐ2を閉止した状態を示している。 Here, FIGS. 1 and 2 shows a state in which closed by a first exhaust manifold M 1 and the second exhaust manifold M exhaust switching valve 7 a divided portion of the 2, 3 and 4 the first exhaust manifold shows a state in which and the closed second path P 2 opened by M 1 and the second exhaust manifold M divided portion of the exhaust switching valve 7 with 2.

また、前記第一経路Ｐ1と前記吸気マニホールド４の入口付近との間がＥＧＲライン９により接続されていると共に、排気ガスＧの再循環量を適宜に調整するＥＧＲバルブ１０と、再循環される排気ガスＧを冷却するためのＥＧＲクーラ１１とが前記ＥＧＲライン９に装備されており、これらＥＧＲライン９とＥＧＲバルブ１０とＥＧＲクーラ１１とによりＥＧＲ装置１２が構成されるようにしてある。 An EGR line 9 connects between the first path P 1 and the vicinity of the inlet of the intake manifold 4, and an EGR valve 10 for appropriately adjusting the recirculation amount of the exhaust gas G. An EGR cooler 11 for cooling the exhaust gas G is provided in the EGR line 9, and the EGR line 9, the EGR valve 10 and the EGR cooler 11 constitute an EGR device 12.

而して、以上に述べた如き過給エンジン１を運転するにあたっては、低速高負荷領域での運転時に排気切替弁７により第一排気マニホールドＭ1と第二排気マニホールドＭ2とを開通し且つ第二経路Ｐ2を閉止する一方、過給圧が排気圧より低い通常運転時には前記排気切替弁７により第一排気マニホールドＭ1と第二排気マニホールドＭ2とを閉止し且つ第二経路Ｐ2を開通する。 And Thus, a such when operating the supercharged engine 1 mentioned above, and opened the to the first exhaust manifold M 1 by the exhaust switching valve 7 during operation at low speed and high load region and the second exhaust manifold M 2 second path while closing the P 2, the boost pressure at the time of lower normal operation than the exhaust pressure closes the a first exhaust manifold M 1 and the second exhaust manifold M 2 by the exhaust switching valve 7 and the second path P 2 To open.

このようにすれば、低速高負荷領域での運転時に第一排気マニホールドＭ1及び第二排気マニホールドＭ2の両方の排気ガスＧを全て第一経路Ｐ1を通してタービン２ａの小スクロールＴ1に導入し、タービン２ａの容量を本来の容量よりも小さくした状態でターボチャージャ２の運転を行い、これにより過給圧を排気圧より低く抑えてＥＧＲ装置１２による排気ガスＧの再循環を支障なく実現することが可能となる。 Thus, introducing a small scroll T 1 of the first exhaust manifold M 1 and the second exhaust manifold M all both exhaust gas G 2 first path P 1 through turbine 2a during operation at low speed and high load region Then, the turbocharger 2 is operated in a state where the capacity of the turbine 2a is smaller than the original capacity, whereby the supercharging pressure is suppressed below the exhaust pressure, and the recirculation of the exhaust gas G by the EGR device 12 is realized without any trouble. It is possible to do.

即ち、図５にタービン２ａの容量（Ａ／Ｒ）と低速領域でのＥＧＲ率との関係を示している通り、タービン２ａの容量（Ａ／Ｒ）が小さくなれば、低速領域での高いＥＧＲ率を得ることが可能であるので、タービン２ａの容量を本来の容量よりも小さくした状態でターボチャージャ２の運転を行えば、本来の容量では不可能であった低速高負荷領域での排気ガスＧの再循環が可能となる。   That is, as shown in FIG. 5, the relationship between the capacity (A / R) of the turbine 2a and the EGR rate in the low-speed region, the smaller the capacity (A / R) of the turbine 2a, the higher the EGR in the low-speed region. Therefore, if the turbocharger 2 is operated with the capacity of the turbine 2a smaller than the original capacity, the exhaust gas in the low-speed and high-load region, which cannot be achieved with the original capacity, can be obtained. G can be recirculated.

一方、過給圧が排気圧より低い通常運転時には排気切替弁７により第一排気マニホールドＭ1と第二排気マニホールドＭ2の夫々の排気ガスＧを第一経路Ｐ1及び第二経路Ｐ2の夫々を通してタービン２ａの小スクロールＴ1及び大スクロールＴ2の夫々に導入し、タービン２ａの容量を本来の容量に戻した状態でターボチャージャ２の運転を行い、これにより高速高負荷領域でのポンピングロスの増加を招くことなくＥＧＲ装置１２による排気ガスＧの再循環を従前通り行うことが可能となる。 On the other hand, at the time of lower normal operation than the supercharging pressure exhaust pressure of the exhaust gas switching valve 7 by the first exhaust manifold M 1 and the second exhaust manifold M 2 of each of the exhaust gas G first path P 1 and the second path P 2 introduced through respective to each of the small scroll T 1 and atmospheric scroll T 2 turbines 2a, performs the operation of the turbocharger 2 capacity turbine 2a while returning to the original volume, thereby pumping at high speed and high load region The recirculation of the exhaust gas G by the EGR device 12 can be performed as before without increasing the loss.

即ち、図６にタービン２ａの容量（Ａ／Ｒ）と高速領域でのポンピングロスとの関係を示している通り、タービン２ａの容量（Ａ／Ｒ）が小さいままでは、高速領域でのポンピングロスの増加が避けられないが、タービン２ａの容量を本来の容量に戻した状態でターボチャージャ２の運転を行えば、高速高負荷領域に移行してもポンピングロスの増加を回避することが可能となる。   That is, as shown in FIG. 6, the relationship between the capacity (A / R) of the turbine 2a and the pumping loss in the high-speed region, the pumping loss in the high-speed region remains small while the capacity (A / R) of the turbine 2a remains small. However, if the operation of the turbocharger 2 is performed in a state where the capacity of the turbine 2a is returned to the original capacity, it is possible to avoid an increase in pumping loss even when shifting to a high-speed and high-load region. Become.

更に、斯かる過給エンジン１を運転するにあたっては、加速時にも排気切替弁７により第一排気マニホールドＭ1と第二排気マニホールドＭ2とを開通し且つ第二経路Ｐ2を閉止することが好ましく、このようにすれば、加速時に前述と同様にタービン２ａの容量を本来の容量よりも小さくした状態でターボチャージャ２の運転を行い、これにより加速時における応答性の大幅な向上を図ることが可能となる。 Furthermore, when operating a such supercharged engine 1, it can also be closed with the first exhaust manifold M 1 by the exhaust switching valve 7 and the second exhaust manifold M 2 opened and and second path P 2 during acceleration Preferably, in this case, the turbocharger 2 is operated in a state where the capacity of the turbine 2a is smaller than the original capacity at the time of acceleration in the same manner as described above, thereby greatly improving the responsiveness at the time of acceleration. Becomes possible.

即ち、一般的なターボチャージャ２の特性として、タービン２ａの容量（Ａ／Ｒ）が小さいと、低速領域から良好な応答性が得られる一方で最高出力が低くなり、逆にタービン２ａの容量（Ａ／Ｒ）が大きいと、応答性が悪くなる一方で高速領域で高出力が得られることが知られており、加速時にもタービン２ａの容量を本来の容量よりも小さくした状態でターボチャージャ２の運転を行えば、加速時における応答性の大幅な向上が得られることは明らかである。   That is, as a general characteristic of the turbocharger 2, when the capacity (A / R) of the turbine 2a is small, good response is obtained from a low-speed region, while the maximum output is low, and conversely, the capacity of the turbine 2a ( It is known that when the A / R is large, the responsiveness is deteriorated and a high output is obtained in a high-speed region. Therefore, even when accelerating, the turbocharger 2 has a smaller capacity than the original capacity. It is clear that the drastic improvement in responsiveness at the time of acceleration can be obtained by performing the operation of

従って、上記形態例によれば、容量可変式のターボチャージャ２を採用せずに低速高負荷領域での排気ガスＧの再循環を実現し且つ高速高負荷領域でのポンピングロスの増加を防ぐことができるので、容量可変式のターボチャージャ２を採用した場合における諸問題を未然に回避することができると共に、全ての運転領域で良好に排気ガスＧを再循環してＮＯx低減性能の大幅な向上を図り且つ高速高負荷領域における燃費の悪化を防止することができる。   Therefore, according to the above embodiment, it is possible to realize the recirculation of the exhaust gas G in a low-speed and high-load region without using the variable-capacity turbocharger 2 and to prevent an increase in pumping loss in a high-speed and high-load region. Therefore, various problems in the case of employing the variable capacity type turbocharger 2 can be avoided beforehand, and the exhaust gas G can be circulated well in all the operation regions to greatly improve the NOx reduction performance. Therefore, it is possible to prevent deterioration of fuel efficiency in a high-speed and high-load region.

また、加速時にタービン２ａの容量を本来の容量よりも小さくした状態でターボチャージャ２の運転を行い、タービン２ａの容量を本来の容量で使用した場合よりも加速時の応答性を向上することができるので、過渡応答性に優れた容量可変式のターボチャージャ２を採用しないことによる過渡応答性の低下を補完することができる。   In addition, the turbocharger 2 is operated in a state where the capacity of the turbine 2a is smaller than the original capacity at the time of acceleration, and the response at the time of acceleration is improved as compared with the case where the capacity of the turbine 2a is used at the original capacity. Therefore, it is possible to compensate for a decrease in the transient response caused by not using the variable capacity turbocharger 2 having excellent transient response.

尚、本発明の過給エンジンは、上述の形態例にのみ限定されるものではなく、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。 It should be noted that the supercharged engine of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

１ 過給エンジン
１ａ 気筒
１ｂ 気筒
１ｃ 気筒
１ｄ 気筒
１ｅ 気筒
１ｆ 気筒
２ ターボチャージャ
２ａ タービン
２ｂ コンプレッサ
５ 排気マニホールド
６ 連絡管部
７ 排気切替弁
１２ ＥＧＲ装置
Ｇ 排気ガス
Ｍ1 第一排気マニホールド
Ｍ2 第二排気マニホールド
Ｐ1 第一経路
Ｐ2 第二経路
Ｔ1 小スクロール
Ｔ2 大スクロール 1 supercharged engine 1a cylinder 1b cylinder 1c cylinder 1d cylinder 1e cylinder 1f cylinder 2 turbocharger 2a turbine 2b compressor 5 exhaust manifold 6 connecting pipe portion 7 exhaust switching valve 12 EGR device G exhaust gas M 1 first exhaust manifold M 2 second Exhaust manifold P 1 First path P 2 Second path T 1 Small scroll T 2 Large scroll

Claims (1)

排気ガスで駆動されるタービンによりコンプレッサを駆動して過給を行うターボチャージャを搭載し、前記タービンより上流側の排気系から排気ガスの一部を抜き出して前記コンプレッサより下流側の吸気系へ再循環するＥＧＲ装置を備えた過給エンジンであって、前記タービンのスクロールを小スクロールと大スクロールとに分割し、各気筒からの排気ガスを集めて前記タービンに導く排気マニホールドの連絡管部を区画壁により前記小スクロールに通じる第一経路と前記大スクロールに通じる第二経路とに分割し、前記区画壁の入側端にフラップ型の排気切替弁の基端部を傾動自在に枢支して、前記排気マニホールドを前記第一経路に通じる第一排気マニホールドと前記第二経路に通じる第二排気マニホールドとに開通閉止自在に分割し且つその開通時に前記排気切替弁により前記第二経路が閉止されるように構成し、前記ＥＧＲ装置の排気ガスの抜き出し位置を前記第一経路としたことを特徴とする過給エンジン。
A turbocharger for supercharging by driving a compressor by a turbine driven by exhaust gas is mounted, a part of the exhaust gas is extracted from an exhaust system on the upstream side of the turbine, and is re-input to an intake system on the downstream side of the compressor. a supercharged engine equipped with a circulating EGR device divides the scroll of the turbine in the small scroll and a large scroll, defining the tube portion of the exhaust manifold leading to the turbine to collect exhaust gases from the cylinders wherein the first path by the wall leading to the small scroll is divided into a second path through the large scroll, a base end portion of the flap-type exhaust switching valve pivotally supported tiltably on entry end of the partition wall , opening closed freely divided the exhaust manifold and a second exhaust manifold communicating with the second path and the first exhaust manifold communicating with the first path One supercharged engine that the by the exhaust switching valve configured as the second path is closed during opening, characterized in that the withdrawal position of the exhaust gas in the EGR device and with the first path.
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