JP2010223077A - Internal combustion engine - Google Patents

Internal combustion engine Download PDF

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JP2010223077A
JP2010223077A JP2009070659A JP2009070659A JP2010223077A JP 2010223077 A JP2010223077 A JP 2010223077A JP 2009070659 A JP2009070659 A JP 2009070659A JP 2009070659 A JP2009070659 A JP 2009070659A JP 2010223077 A JP2010223077 A JP 2010223077A
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pressure stage
low
passage
egr
pressure
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Akihide Okuyama
晃英 奥山
Osamu Igarashi
修 五十嵐
Norihiko Sumi
範彦 住
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Toyota Motor Corp
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Toyota Motor Corp
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    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00Road transport of goods or passengers
    • Y02T10/10Internal combustion engine [ICE] based vehicles
    • Y02T10/12Improving ICE efficiencies

Abstract

<P>PROBLEM TO BE SOLVED: To select optimal EGR in response to an engine operation condition. <P>SOLUTION: An intake passage 3 of an engine 1 includes a low pressure stage compressor 5C of a low pressure stage turbocharger 5 and a high pressure stage compressor 6C of a high pressure stage turbocharger 6 from the upstream side. An exhaust passage 4 includes a high pressure stage turbine 6T of the high pressure stage turbocharger 6 and a low pressure stage turbine 5T of the low pressure stage turbocharger 5 from the upstream side. An EGR device includes a first EGR passage 11 for taking out and recirculating exhaust gas from the upstream side of the low pressure stage turbine 5T to the upstream side of the low pressure stage compressor 5C of the intake passage 3 on the downstream side of the high pressure stage turbine 6T of the exhaust passage 4, a second EGR passage 12 for taking out and recirculating the exhaust gas from the downstream side of the low pressure stage turbine 5T of the exhaust passage 4 to the upstream side of the low pressure stage compressor 5C of the intake passage 3, and these opening-closing vales 21 and 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、内燃機関に関し、特に、低圧段ターボ過給機と高圧段ターボ過給機とを備える内燃機関において、排気通路から排気の一部を吸気通路に再循環するEGR装置に関する。   The present invention relates to an internal combustion engine, and more particularly, to an EGR device that recirculates part of exhaust from an exhaust passage to an intake passage in an internal combustion engine that includes a low-pressure turbocharger and a high-pressure turbocharger.

特許文献1には、いわゆる2ステージターボシステムが開示されている。これは、吸気通路に、上流側から順に、低圧段コンプレッサと高圧段コンプレッサとを配置し、排気通路に、上流側から順に、高圧段タービンと低圧段タービンとを配置する。そして、低圧段タービンと低圧段コンプレッサとを同軸に連結して、低圧段ターボ過給機を構成し、高圧段タービンと高圧段コンプレッサとを同軸に連結して、高圧段ターボ過給機を構成する。このようにして、吸気を低圧段コンプレッサと高圧段コンプレッサとで2段階に過給することにより、低回転域から効率良く過給圧力を高めることができ、機関の出力向上及び燃費低減を図ることができる。   Patent Document 1 discloses a so-called two-stage turbo system. In this configuration, a low-pressure stage compressor and a high-pressure stage compressor are arranged in the intake passage sequentially from the upstream side, and a high-pressure turbine and a low-pressure stage turbine are arranged in the exhaust passage sequentially from the upstream side. A low-pressure stage turbine and a low-pressure stage compressor are coaxially connected to constitute a low-pressure stage turbocharger, and a high-pressure stage turbine and a high-pressure stage compressor are coaxially connected to constitute a high-pressure stage turbocharger. To do. In this way, by supercharging the intake air in two stages with the low-pressure stage compressor and the high-pressure stage compressor, the supercharging pressure can be increased efficiently from the low speed range, and the engine output is improved and the fuel consumption is reduced. Can do.

また、特許文献1には、2ステージターボシステムにおいて、排気通路から排気の一部を吸気通路に再循環するEGR装置として、排気通路の高圧段タービン下流で低圧段タービン上流から排気を取出して吸気通路の低圧段タービン上流に再循環するEGR通路を設けたものが開示されている。これによれば、過給圧が排気圧力を超える低速高負荷域においても、EGR通路の入口側と出口側の差圧を確保して、必要とするEGR率を確保できる。   In Patent Document 1, as an EGR device that recirculates a part of exhaust gas from an exhaust passage to an intake passage in a two-stage turbo system, exhaust is taken out from the upstream of a low-pressure turbine downstream of the high-pressure turbine in the exhaust passage. There is disclosed an EGR passage that is recirculated upstream of a low-pressure turbine in the passage. According to this, even in a low speed and high load region where the supercharging pressure exceeds the exhaust pressure, it is possible to secure the differential pressure between the inlet side and the outlet side of the EGR passage, and to secure the required EGR rate.

特開2007−224801号公報JP 2007-224801 A

しかしながら、特許文献1に記載の従来技術においては、EGR通路の入口側と出口側の差圧を確保して、差圧大での大量EGRが可能となるが、機関運転領域の全域でEGRを入れる場合、運転条件によっては、不都合があった。例えば高負荷時に、排気温度が高くなると、再循環されるEGRガスの温度が高すぎて、本来のEGRの効果(NOx低減のための燃焼温度抑制)が十分に発揮されなくなる恐れがあった。   However, in the prior art described in Patent Document 1, a large amount of EGR with a large differential pressure is possible by securing a differential pressure between the inlet side and the outlet side of the EGR passage. In some cases, there were inconveniences depending on the operating conditions. For example, if the exhaust gas temperature becomes high at a high load, the temperature of the recirculated EGR gas is too high, and the original EGR effect (combustion temperature suppression for reducing NOx) may not be sufficiently exhibited.

本発明は、このような実状に鑑み、機関運転条件に応じて最適なEGRを選択可能とすることを課題とする。   In view of such a situation, an object of the present invention is to make it possible to select an optimal EGR according to engine operating conditions.

このため、本発明は、いわゆる2ステージターボシステムを備える内燃機関のEGR装置として、排気通路の高圧段タービン下流で低圧段タービン上流から排気を取出して吸気通路の低圧段コンプレッサ上流へ再循環する第1EGR通路と、排気通路の低圧段タービン下流から排気を取出して吸気通路の低圧段コンプレッサ上流へ再循環する第2EGR通路と、機関運転条件に応じて前記第1及び第2EGR通路を選択するEGR通路選択手段と、を設ける構成とする。   Therefore, the present invention is an EGR device for an internal combustion engine having a so-called two-stage turbo system, in which the exhaust is taken out from the upstream of the low-pressure stage turbine downstream of the high-pressure turbine in the exhaust passage and recirculated to the upstream of the low-pressure compressor of the intake passage. 1 EGR passage, a second EGR passage that takes the exhaust gas downstream of the low-pressure stage turbine of the exhaust passage and recirculates it upstream of the low-pressure stage compressor of the intake passage, and an EGR passage that selects the first and second EGR passages according to engine operating conditions And selecting means.

本発明によれば、前記第1EGR通路の選択により、比較的高温、高圧の位置から排気を取出すことで、例えば差圧大でのEGRを選択できる。また、前記第2EGR通路の選択により、比較的低温、低圧の位置から排気を取出すことで、例えば低温のEGRが可能となる。よって、運転条件に応じて、例えば、差圧大でのEGRと低温のEGRとを選択できる。   According to the present invention, by selecting the first EGR passage, for example, EGR with a large differential pressure can be selected by removing the exhaust gas from a relatively high temperature and high pressure position. Further, by selecting the second EGR passage, the exhaust gas is taken out from a relatively low temperature and low pressure position, so that, for example, low temperature EGR is possible. Thus, for example, EGR with a large differential pressure and low-temperature EGR can be selected according to operating conditions.

本発明の一実施形態を示す過給機付き内燃機関のシステム図The system diagram of the internal combustion engine with a supercharger which shows one Embodiment of this invention EGR通路選択の運転領域を示す図The figure which shows the operation area of EGR passage selection

以下に本発明の一実施形態を図面に基づいて詳細に説明する。   Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

図1に示す内燃機関1は、例えばディーゼルエンジンであり、各気筒の燃焼室は、吸気弁及び排気弁(図示せず)を備えると共に、直噴式の燃料噴射弁(図示せず)を備えている。   An internal combustion engine 1 shown in FIG. 1 is, for example, a diesel engine, and a combustion chamber of each cylinder includes an intake valve and an exhaust valve (not shown) and a direct injection type fuel injection valve (not shown). Yes.

これにより、各気筒の燃焼室には、エアクリーナ2から取入れた吸入空気が、吸気通路3を通って、吸気弁の開時に吸入される。そして、圧縮行程にて燃料噴射弁より燃料が噴射され、燃焼室内で吸入空気と燃料とが圧縮着火により燃焼する。燃焼後の排気は、排気弁の開弁により、排気通路4へ排出される。   Thereby, the intake air taken in from the air cleaner 2 is drawn into the combustion chamber of each cylinder through the intake passage 3 when the intake valve is opened. Then, fuel is injected from the fuel injection valve in the compression stroke, and the intake air and the fuel are combusted by compression ignition in the combustion chamber. The exhaust gas after combustion is discharged into the exhaust passage 4 by opening the exhaust valve.

内燃機関1は、また、いわゆる2ステージターボシステムを構成する2つのターボ過給機、すなわち、低圧段ターボ過給機5と、高圧段ターボ過給機6とを備えている。   The internal combustion engine 1 also includes two turbochargers constituting a so-called two-stage turbo system, that is, a low-pressure stage turbocharger 5 and a high-pressure stage turbocharger 6.

低圧段ターボ過給機5は、吸気通路3の比較的上流側に配置されて吸気を過給する低圧段コンプレッサ5Cと、排気通路4の比較的下流側に配置されて排気の圧力エネルギーにより回転する低圧段タービン5Tと、低圧段タービン5Tにより低圧段コンプレッサ5Cを駆動するように両者を同軸に連結する駆動軸5Sと、を含んで構成される。   The low-pressure turbocharger 5 is disposed on the relatively upstream side of the intake passage 3 to supercharge intake air, and is disposed on the relatively downstream side of the exhaust passage 4 and is rotated by the pressure energy of the exhaust. And a drive shaft 5S that coaxially couples the low-pressure stage turbine 5T to drive the low-pressure stage compressor 5C by the low-pressure stage turbine 5T.

高圧段ターボ過給機6は、吸気通路3の比較的下流側(前記低圧段コンプレッサ5Cより下流側)に配置されて吸気を過給する高圧段コンプレッサ6Cと、排気通路4の比較的上流側(前記低圧段タービン5Tより上流側)に配置されて排気の圧力エネルギーにより回転する高圧段タービン6Tと、高圧段タービン6Tにより高圧段コンプレッサ6Cを駆動するように両者を同軸に連結する駆動軸6Sと、を含んで構成される。   The high-pressure turbocharger 6 is disposed on the relatively downstream side of the intake passage 3 (downstream side from the low-pressure compressor 5C) and supercharges intake air, and the upstream side of the exhaust passage 4 is relatively upstream. A high-pressure stage turbine 6T that is disposed (upstream from the low-pressure stage turbine 5T) and rotates by the pressure energy of the exhaust, and a drive shaft 6S that coaxially connects the high-pressure stage turbine 6T to drive the high-pressure stage compressor 6C. And comprising.

言い換えれば、吸気通路3に、上流側から順に、低圧段コンプレッサ5Cと高圧段コンプレッサ6Cとを配置し、排気通路4に、上流側から順に、高圧段タービン6Tと低圧段タービン5Tとを配置している。そして、低圧段タービン5Tと低圧段コンプレッサ5Cとを同軸に連結して、低圧段ターボ過給機5を構成し、高圧段タービン6Tと高圧段コンプレッサ6Cとを同軸に連結して、高圧段ターボ過給機6を構成している。   In other words, the low-pressure stage compressor 5C and the high-pressure stage compressor 6C are arranged in the intake passage 3 sequentially from the upstream side, and the high-pressure stage turbine 6T and the low-pressure stage turbine 5T are arranged in the exhaust passage 4 sequentially from the upstream side. ing. Then, the low-pressure stage turbine 5T and the low-pressure stage compressor 5C are connected coaxially to constitute the low-pressure stage turbocharger 5, and the high-pressure stage turbine 6T and the high-pressure stage compressor 6C are connected coaxially to form the high-pressure stage turbo. A supercharger 6 is configured.

従って、吸気通路3では、エアクリーナ2から取入れた吸入空気が、低圧段コンプレッサ5Cにより過給され、更に高圧段コンプレッサ6Cにより過給され、インタークーラ(図示せず)で冷却された後、吸気マニホールド(図示せず)を介して、各気筒の燃焼室に流入する。   Therefore, in the intake passage 3, the intake air taken in from the air cleaner 2 is supercharged by the low-pressure stage compressor 5C, further supercharged by the high-pressure stage compressor 6C, and cooled by the intercooler (not shown), and then the intake manifold. It flows into the combustion chamber of each cylinder via (not shown).

このようにして、吸気を低圧段コンプレッサ5Cと高圧段コンプレッサ6Cとで2段階に過給することにより、低回転域から効率良く過給圧力を高めることができ、エンジンの出力向上及び燃費低減を図ることができる。   In this way, by supercharging the intake air in two stages with the low-pressure compressor 5C and the high-pressure compressor 6C, the supercharging pressure can be increased efficiently from the low rotation range, and the engine output and fuel consumption can be reduced. You can plan.

また、排気通路4では、各気筒の排気が排気マニホールド(図示せず)にて合流し、先ず高圧段タービン6Tを通過する際に、排気の圧力エネルギーで、高圧段タービン6Tを駆動し、次いで低圧段タービン5Tを通過する際に、排気の圧力エネルギーで、低圧段タービン5Tを駆動する。その後、排気は、排気浄化触媒及びDPFを含む排気後処理装置7を通って、排出される。   Further, in the exhaust passage 4, when the exhaust of each cylinder joins at an exhaust manifold (not shown) and first passes through the high-pressure turbine 6T, the high-pressure turbine 6T is driven with the pressure energy of the exhaust, and then When passing through the low pressure turbine 5T, the low pressure turbine 5T is driven by the pressure energy of the exhaust. Thereafter, the exhaust gas is exhausted through an exhaust gas aftertreatment device 7 including an exhaust gas purification catalyst and a DPF.

尚、必要により、排気通路4には、高圧段タービン6T及び低圧段タービン5Tをそれぞれバイパスするバイパス通路と、各バイパス通路のバイパス制御のための制御弁とが設けられるが、図示は省略した。また、必要により、吸気通路3には、高圧段コンプレッサ6Cをバイパスするバイパス通路と、このバイパス通路のバイパス制御のための制御弁とが設けられるが、図示は省略した。   If necessary, the exhaust passage 4 is provided with a bypass passage that bypasses the high-pressure turbine 6T and the low-pressure turbine 5T, and a control valve for bypass control of each bypass passage, but the illustration is omitted. If necessary, the intake passage 3 is provided with a bypass passage that bypasses the high-pressure compressor 6C and a control valve for bypass control of the bypass passage, but the illustration is omitted.

次に、上記の2ステージターボシステムにおける、EGR装置について説明する。   Next, the EGR device in the above-described two-stage turbo system will be described.

EGR装置としては、排気通路4の高圧段タービン6T下流で低圧段タービン5T上流から排気を取出して吸気通路3の低圧段コンプレッサ5C上流へ再循環する第1EGR通路11と、排気通路4の低圧段タービン5T下流から排気を取出して吸気通路3の低圧段コンプレッサ5C上流へ再循環する第2EGR通路12と、を設ける。   The EGR device includes a first EGR passage 11 that extracts exhaust from the high-pressure stage turbine 6T downstream of the exhaust passage 4 and upstream of the low-pressure stage turbine 5T and recirculates the intake passage 3 upstream of the low-pressure stage compressor 5C, and the low-pressure stage of the exhaust passage 4 There is provided a second EGR passage 12 that takes out the exhaust from the downstream of the turbine 5T and recirculates the intake passage 3 upstream of the low-pressure stage compressor 5C.

但し、これらの第1及び第2EGR通路11、12は、EGRガスの入口部は異なるが、出口部は同じでよいため、本実施形態では、入口部11aからの第1EGR通路11と入口部12aからの第2EGR通路12とを途中で合流させて、共通EGR通路13とし、この共通EGR通路13を単一の出口部13aに接続している。また、共通EGR通路13にはEGRクーラ14を配置している。   However, since the first and second EGR passages 11 and 12 have different EGR gas inlet portions, but the outlet portions may be the same, in this embodiment, the first EGR passage 11 and the inlet portion 12a from the inlet portion 11a. The second EGR passage 12 is joined together to form a common EGR passage 13, and the common EGR passage 13 is connected to a single outlet portion 13a. An EGR cooler 14 is disposed in the common EGR passage 13.

また、第1及び第2EGR通路11、12の選択手段として、第1EGR通路11の入口部11aに開閉弁21を設けると共に、第2EGR通路12の入口部12aに開閉弁22を設けている。   Further, as a means for selecting the first and second EGR passages 11 and 12, an opening / closing valve 21 is provided at the inlet portion 11 a of the first EGR passage 11, and an opening / closing valve 22 is provided at the inlet portion 12 a of the second EGR passage 12.

従って、第1開閉弁21を開いて第2開閉弁22を閉じることにより、第1EGR通路11を選択でき、逆に、第1開閉弁21を閉じて第2開閉弁22を開くことにより、第2EGR通路12を選択できる。   Accordingly, the first EGR passage 11 can be selected by opening the first on-off valve 21 and closing the second on-off valve 22, and conversely, by closing the first on-off valve 21 and opening the second on-off valve 22, 2EGR passage 12 can be selected.

尚、必要により、吸気通路3におけるEGR通路出口部13aの上流側に吸気制御弁(吸気絞り弁)23を設けてもよい。   If necessary, an intake control valve (intake throttle valve) 23 may be provided upstream of the EGR passage outlet portion 13a in the intake passage 3.

前記第1及び第2開閉弁21、22の開閉制御は、エンジン制御用の電子制御ユニット(ECU)30により行うようになっている。   The opening / closing control of the first and second opening / closing valves 21 and 22 is performed by an electronic control unit (ECU) 30 for engine control.

ECU30は、マイクロコンピュータを含んで構成され、アクセル開度センサ31、エンジン回転数センサ32などからエンジン運転条件に関連する信号が入力されており、これらの信号に基づいて、検出されるエンジン運転条件に基づいて、燃料噴射弁の燃料噴射量、噴射時期などを制御すると共に、前記開閉弁21、22の開閉を制御する。また、必要であれば、吸気制御弁23の開度を制御する。   The ECU 30 includes a microcomputer, and receives signals related to engine operating conditions from the accelerator opening sensor 31, the engine speed sensor 32, etc., and the engine operating conditions detected based on these signals. Based on the above, the fuel injection amount and injection timing of the fuel injection valve are controlled, and the opening and closing of the on-off valves 21 and 22 is controlled. If necessary, the opening degree of the intake control valve 23 is controlled.

次にエンジン運転条件に応じた前記開閉弁21、22の制御(EGR通路の選択制御)について説明する。   Next, control of the on-off valves 21 and 22 (EGR passage selection control) according to engine operating conditions will be described.

図2はEGR通路選択の運転領域を示すもので、横軸をエンジン回転数Ne、縦軸をエンジントルクTeとすると、図示Aの低負荷域(低回転低負荷域)と図示Bの高負荷域(高回転高負荷域)と分けて制御する。尚、ECU30において、エンジン回転数Neはエンジン回転数センサ32により検出するが、エンジントルクTeはエンジン運転条件に基づいて自ら制御している燃料噴射量に基づいて算出する。   FIG. 2 shows the operation region of EGR passage selection. When the horizontal axis is the engine speed Ne and the vertical axis is the engine torque Te, the low load region (low rotation low load region) shown in FIG. It is controlled separately from the area (high rotation and high load area). In the ECU 30, the engine speed Ne is detected by the engine speed sensor 32, but the engine torque Te is calculated based on the fuel injection amount controlled by the engine 30 based on the engine operating conditions.

図示Aの低負荷域では、第1開閉弁21を開いて、第2開閉弁22を閉じることにより、第1EGR通路11を選択する。   In the low load region shown in FIG. A, the first EGR passage 11 is selected by opening the first on-off valve 21 and closing the second on-off valve 22.

また、図示Bの高負荷域では、第1開閉弁21を閉じて、第2開閉弁22を開くことにより、第2EGR通路12を選択する。   Further, in the high load region shown in FIG. B, the second EGR passage 12 is selected by closing the first on-off valve 21 and opening the second on-off valve 22.

従って、図示Aの低負荷域では、第1EGR通路11を選択することにより、排気通路4の高圧段タービン6T下流で低圧段タービン5T上流(入口部11a)から排気を取出して、吸気通路3の低圧段コンプレッサ5C上流(出口部13a)へ再循環する。すなわち、比較的高温、高圧の位置から排気を取出すことで、差圧大でのEGRを選択できる。   Therefore, in the low load region shown in FIG. A, by selecting the first EGR passage 11, the exhaust is taken out from the high pressure stage turbine 6T downstream of the exhaust passage 4 and from the low pressure stage turbine 5T upstream (inlet portion 11a), and the intake passage 3 Recirculation is performed upstream of the low-pressure stage compressor 5C (outlet portion 13a). That is, EGR with a large differential pressure can be selected by taking exhaust gas from a relatively high temperature and high pressure position.

また、図示Bの高負荷域では、第2EGR通路12を選択することにより、排気通路4の低圧段タービン5T下流(入口部12a)から排気を取出して、吸気通路3の低圧段コンプレッサ5C上流(出口部13a)へ再循環する。すなわち、比較的低温、低圧の位置から排気を取出すことで、低温のEGRを選択できる。   Further, in the high load region shown in FIG. B, by selecting the second EGR passage 12, the exhaust gas is taken out from the low-pressure turbine 5T downstream (inlet portion 12a) of the exhaust passage 4 and upstream of the low-pressure compressor 5C of the intake passage 3 ( Recirculate to outlet 13a). That is, a low temperature EGR can be selected by taking out the exhaust from a relatively low temperature and low pressure position.

更に詳しく説明すると、図示Aの低負荷域では、低負荷のため、高負荷との比較で、排気温度が低く、排気圧力も低い。従って、図示Aの低負荷域では、第1EGR通路11を選択し、高圧側の位置から排気を取出すことで、EGR通路の入口側と出口側の差圧を大きくして、低負荷にもかかわらず、差圧大での大量EGRが可能となる。   More specifically, in the low load region of FIG. A, since the load is low, the exhaust temperature is lower and the exhaust pressure is lower than the high load. Accordingly, in the low load region shown in FIG. A, the first EGR passage 11 is selected and the exhaust gas is taken out from the position on the high pressure side to increase the differential pressure between the inlet side and the outlet side of the EGR passage. Therefore, a large amount of EGR with a large differential pressure becomes possible.

特に近年は排気NOxの大幅低減要求に対し、大量EGRが求められており、この要求を満たすことができる。   In particular, in recent years, a large amount of EGR has been demanded in response to a demand for greatly reducing exhaust NOx, and this demand can be satisfied.

また、従来は、大量EGRのため、EGR通路の入口側と出口側の差圧を大きくとるために、吸気通路3のEGR通路出口部上流の吸気制御弁23が必須で、これがコスト高の要因となっていたが、吸気制御弁23の廃止が可能となる。   Conventionally, because of the large amount of EGR, in order to increase the differential pressure between the inlet side and the outlet side of the EGR passage, the intake control valve 23 upstream of the EGR passage outlet portion of the intake passage 3 is essential, which is a factor of high cost. However, the intake control valve 23 can be abolished.

また、従来は、大量EGRのため、EGR通路の入口側と出口側の差圧を大きくとるために、吸気通路3のEGR通路出口部上流の吸気制御弁23を大きく絞って大きな負圧を発生させる必要があり、これにより、低圧段コンプレッサ5C内に大きな負圧が発生し、ターボ潤滑油の吸気系への洩れ流出が懸念されていた。しかも、2ステージターボの場合、通常制御では、低圧段コンプレッサ5Cの回転数が低く、シングルターボの場合よりも、洩れ性能的に極めて不利であった。この点、本実施形態では、吸気制御弁23を廃止可能、若しくは吸気制御弁23を設けたとしても大きく絞る必要はないので、負圧の発生を抑制でき、ターボ潤滑油の洩れを防止することができる。   Conventionally, because of a large amount of EGR, in order to increase the differential pressure between the inlet side and the outlet side of the EGR passage, the intake control valve 23 upstream of the EGR passage outlet portion of the intake passage 3 is greatly throttled to generate a large negative pressure. As a result, a large negative pressure is generated in the low-pressure compressor 5C, and there is a concern about leakage of turbo lubricating oil to the intake system. In addition, in the case of the two-stage turbo, the rotation speed of the low-pressure stage compressor 5C is low in the normal control, which is extremely disadvantageous in terms of leakage performance compared to the case of the single turbo. In this regard, in the present embodiment, the intake control valve 23 can be abolished, or even if the intake control valve 23 is provided, it is not necessary to greatly reduce the intake pressure. Therefore, generation of negative pressure can be suppressed, and leakage of turbo lubricating oil can be prevented. Can do.

また、図示Aの低負荷域では、第1EGR通路11を選択することで、高温側の位置から排気を取出すことになるが、低負荷ゆえ、そもそも低温であるので、高温EGRによる充填効率低下等の恐れはない。   In the low load region shown in FIG. A, the first EGR passage 11 is selected to take out the exhaust from the position on the high temperature side. However, because of the low load, the temperature is low in the first place. There is no fear of.

暖機時について考えると、高温側の位置から排気を取出すことで、暖機時の燃焼温度を高めて、早期暖機を促進できる。従って、低温時に早期暖機用として使うこともできる。また、EGR配管の氷結対策にもつながる。   Considering the warm-up time, the exhaust temperature is taken out from the position on the high temperature side, so that the combustion temperature at the warm-up time can be increased and early warm-up can be promoted. Therefore, it can be used for early warm-up at low temperatures. It also leads to measures against freezing of EGR piping.

一方、図示Bの高負荷域では、高負荷のため、低負荷との比較で、排気温度が高く、排気圧力も高い。従って、図示Bの高負荷域では、第2EGR通路12を選択し、低温側の位置から排気を取出すことで、高負荷にもかかわらず、低温のEGRが可能となる。   On the other hand, in the high load region shown in FIG. B, the exhaust temperature is higher and the exhaust pressure is higher than the low load because of the high load. Therefore, in the high load region shown in FIG. B, by selecting the second EGR passage 12 and taking out the exhaust from the low temperature side position, low temperature EGR is possible despite the high load.

また、図示Bの高負荷領域では、第2EGR通路12を選択することで、低圧側の位置から排気を取出すことになるが、高負荷ゆえ、そもそも高圧であるので、EGR通路の入口側と出口側の差圧は確保でき、十分な大量EGRが可能となる。   Further, in the high load region shown in FIG. B, by selecting the second EGR passage 12, the exhaust gas is taken out from the low pressure side position. The differential pressure on the side can be secured, and a sufficiently large amount of EGR becomes possible.

従って、このようなEGR通路の選択制御により、エンジン運転領域の全域で、比較的低温の排気を、大量にEGR可能となり、EGRによるNOx低減効果及び燃費低減効果を十分に発揮させることが可能となる。   Therefore, by such EGR passage selection control, it is possible to perform EGR in a large amount of relatively low temperature exhaust in the entire engine operation region, and it is possible to sufficiently exhibit the NOx reduction effect and the fuel consumption reduction effect by EGR. Become.

尚、以上の説明では、EGR通路選択手段として、各EGR通路11、12に開閉弁21、22を設けたが、出口側の共通EGR通路13への合流部に、流路切換弁を設けるなどしてもよく、通路の選択形式はどのようなものであってもよい。   In the above description, as the EGR passage selection means, the open / close valves 21 and 22 are provided in the respective EGR passages 11 and 12, but a flow path switching valve is provided at the junction with the common EGR passage 13 on the outlet side. Alternatively, any type of passage may be selected.

また、以上の説明では、ディーゼルエンジンを例にとって説明したが、ガソリンエンジンを含む内燃機関一般に適用可能であることは言うまでもない。   In the above description, the diesel engine has been described as an example, but it goes without saying that the present invention can be applied to general internal combustion engines including a gasoline engine.

1 内燃機関(ディーゼルエンジン)
2 エアクリーナ
3 吸気通路
4 排気通路
5 低圧段ターボ過給機
5C 低圧段コンプレッサ
5T 低圧段タービン
5S 駆動軸
6 高圧段ターボ過給機
6C 高圧段コンプレッサ
6T 高圧段タービン
6S 駆動軸
7 排気後処理装置
11 第1EGR通路
11a 入口部
12 第2EGR通路
12a 入口部
13 共通EGR通路
13a 出口部
14 EGRクーラ
21 第1開閉弁
22 第2開閉弁
23 吸気制御弁
30 ECU
31 アクセル開度センサ
32 エンジン回転数センサ
1 Internal combustion engine (diesel engine)
DESCRIPTION OF SYMBOLS 2 Air cleaner 3 Intake passage 4 Exhaust passage 5 Low pressure stage turbocharger 5C Low pressure stage compressor 5T Low pressure stage turbine 5S Drive shaft 6 High pressure stage turbocharger 6C High pressure stage compressor 6T High pressure stage turbine 6S Drive shaft 7 Exhaust aftertreatment device 11 First EGR passage 11a Inlet portion 12 Second EGR passage 12a Inlet portion 13 Common EGR passage 13a Outlet portion 14 EGR cooler 21 First on-off valve 22 Second on-off valve 23 Intake control valve 30 ECU
31 Accelerator opening sensor 32 Engine speed sensor

Claims (1)

吸気通路に配置されて吸気を過給する低圧段コンプレッサと、排気通路に配置されて排気の圧力エネルギーにより回転し前記低圧段コンプレッサを駆動する低圧段タービンと、を含んで構成される低圧段ターボ過給機と、
吸気通路における前記低圧段コンプレッサの下流側に配置されて吸気を過給する高圧段コンプレッサと、排気通路における前記低圧段タービンの上流側に配置されて排気の圧力エネルギーにより回転し前記高圧段コンプレッサを駆動する高圧段タービンと、を含んで構成される高圧段ターボ過給機と、
排気通路から排気の一部を吸気通路に再循環するEGR装置と、を備え、
前記EGR装置は、排気通路の前記高圧段タービン下流で前記低圧段タービン上流から排気を取出して吸気通路の前記低圧段コンプレッサ上流へ再循環する第1EGR通路と、排気通路の前記低圧段タービン下流から排気を取出して吸気通路の前記低圧段コンプレッサ上流へ再循環する第2EGR通路と、機関運転条件に応じて前記第1及び第2EGR通路を選択するEGR通路選択手段と、を含んで構成される、内燃機関。
A low-pressure stage turbo that includes a low-pressure stage compressor that is disposed in the intake passage and supercharges intake air, and a low-pressure stage turbine that is disposed in the exhaust passage and rotates by the pressure energy of the exhaust to drive the low-pressure stage compressor. A turbocharger,
A high-pressure stage compressor that is disposed on the downstream side of the low-pressure stage compressor in the intake passage and supercharges intake air; and a high-pressure stage compressor that is disposed on the upstream side of the low-pressure turbine in the exhaust path and rotates by the pressure energy of the exhaust. A high-pressure stage turbocharger configured to include a high-pressure stage turbine to be driven,
An EGR device that recirculates part of the exhaust gas from the exhaust passage to the intake passage,
The EGR device includes a first EGR passage that extracts exhaust from the upstream of the low-pressure stage turbine downstream of the high-pressure stage turbine in the exhaust passage and recirculates to the upstream of the low-pressure stage compressor of the intake passage, and from the downstream of the low-pressure stage turbine of the exhaust passage. A second EGR passage that takes out exhaust gas and recirculates the intake passage upstream of the low-pressure stage compressor; and an EGR passage selection means that selects the first and second EGR passages according to engine operating conditions. Internal combustion engine.
JP2009070659A 2009-03-23 2009-03-23 Internal combustion engine Pending JP2010223077A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012122434A (en) * 2010-12-10 2012-06-28 Mazda Motor Corp Diesel engine
JP2012132337A (en) * 2010-12-20 2012-07-12 Toyota Motor Corp Control device of internal combustion engine with supercharger
WO2013011839A1 (en) * 2011-07-15 2013-01-24 三菱重工業株式会社 Electric supercharger, method for assembling same, and internal combustion engine

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012122434A (en) * 2010-12-10 2012-06-28 Mazda Motor Corp Diesel engine
JP2012132337A (en) * 2010-12-20 2012-07-12 Toyota Motor Corp Control device of internal combustion engine with supercharger
WO2013011839A1 (en) * 2011-07-15 2013-01-24 三菱重工業株式会社 Electric supercharger, method for assembling same, and internal combustion engine
JP2013024059A (en) * 2011-07-15 2013-02-04 Mitsubishi Heavy Ind Ltd Electric supercharge compressor, method for assembling the same, and internal combustion engine
CN103649545A (en) * 2011-07-15 2014-03-19 三菱重工业株式会社 Electric supercharger, method for assembling same, and internal combustion engine
US9470140B2 (en) 2011-07-15 2016-10-18 Mitsubishi Heavy Industries, Ltd. Electric supercharger, assembling method of the same, and internal combustion engine

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