JPH0518254A - Intake device of diesel engine - Google Patents
Intake device of diesel engineInfo
- Publication number
- JPH0518254A JPH0518254A JP3171065A JP17106591A JPH0518254A JP H0518254 A JPH0518254 A JP H0518254A JP 3171065 A JP3171065 A JP 3171065A JP 17106591 A JP17106591 A JP 17106591A JP H0518254 A JPH0518254 A JP H0518254A
- Authority
- JP
- Japan
- Prior art keywords
- intake
- intake air
- valve
- egr
- engine
- 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.)
- Granted
Links
Classifications
-
- 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
-
- 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
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
-
- 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)
- Exhaust-Gas Circulating Devices (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、ディーゼルエンジンの
吸気装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine intake system.
【０００２】[0002]
【従来の技術】近年、ディーゼルエンジンにおいては、
排気エミッションの低減とくにＮＯx発生量の低減が求
められているが、ＮＯx発生量を低減するには、燃焼室
内の燃焼温度を過剰に上昇させないようにすることが必
要である。そして、一般に、燃焼温度の不必要なな上昇
を抑制する手法として、燃焼室内での燃料の燃焼性の改
善、吸気系への排気ガスの導入(ＥＧＲ)等が知られてい
る。ここで、燃焼性の改善手法として、運転状態に応じ
て燃焼室内での吸気旋回流すなわちスワールの強さを制
御するといった、いわゆるスワール制御が従来より知ら
れている。例えば、各気筒に夫々２つの吸気ポートを設
け、一方の吸気ポートを燃焼室の周方向に向けて開口さ
せ、あるいはヘリカル状に形成するなどしてスワールを
生成させるようにする一方、両吸気ポートまたは一方の
吸気ポートを開閉する開閉弁を設け、エンジンの運転状
態に応じて開閉弁を開閉し、燃焼室内のスワールの強さ
を変えて、燃焼性を好ましく制御するようになっている
(特開昭６２−１７４５３３号公報参照)。2. Description of the Related Art Recently, in diesel engines,
Reduction of exhaust emission, especially reduction of NOx generation amount is required, but in order to reduce NOx generation amount, it is necessary to prevent the combustion temperature in the combustion chamber from rising excessively. Then, generally, as a method for suppressing an unnecessary increase in the combustion temperature, improvement of the combustibility of fuel in the combustion chamber, introduction of exhaust gas into the intake system (EGR), etc. are known. Here, as a method of improving the combustibility, so-called swirl control is conventionally known in which the swirl flow of the intake air in the combustion chamber, that is, the strength of the swirl is controlled according to the operating state. For example, two intake ports are provided in each cylinder, and one intake port is opened in the circumferential direction of the combustion chamber or is formed in a helical shape to generate swirl, while both intake ports are provided. Alternatively, an on-off valve that opens and closes one of the intake ports is provided, and the on-off valve is opened and closed according to the operating condition of the engine to change the strength of the swirl in the combustion chamber to control the combustibility preferably.
(See JP-A-62-174533).
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、かかる
従来のスワール制御は、主として燃焼性を高めてエンジ
ン出力の向上を図ることを目的としているので、排気エ
ミッションの低減には直接的にはつながらないといった
問題がある。また、ＮＯx対策としての吸気系へのＥＧ
Ｒガスの導入は、従来より広く行なわれている。しかし
ながら、かかるＥＧＲ機構を過給機付エンジンに設けた
場合、吸気圧が排気圧より高くなる運転領域では、通常
ＥＧＲガスの吸気系への導入が不可能であるばかりか、
逆に吸気が排気系に流入するといった問題がある。とく
に機械式過給機では、低回転領域から吸気圧が高くなる
ので、かかる不具合が著しい。However, since the conventional swirl control is mainly intended to enhance the combustibility and improve the engine output, it does not directly lead to the reduction of exhaust emission. There is. In addition, EG to the intake system as a NOx countermeasure
The introduction of R gas has been performed more widely than before. However, when such an EGR mechanism is provided in a supercharged engine, not only is it generally impossible to introduce EGR gas into the intake system in an operating region where the intake pressure is higher than the exhaust pressure,
On the contrary, there is a problem that intake air flows into the exhaust system. Particularly, in the mechanical supercharger, the intake pressure becomes high from the low rotation speed region, so such a problem is remarkable.
【０００４】本発明は、上記従来の問題点を解決するた
めになされたものであって、エンジン出力を高めつつ、
ＮＯx等の排気エミッションを有効に低減することがで
きるディーゼルエンジンの吸気装置を提供することを目
的とする。The present invention has been made to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide an intake system for a diesel engine that can effectively reduce exhaust emissions such as NOx.
【０００５】[0005]
【課題を解決するための手段】上記の目的を達成するた
めに、第１の発明は、各気筒に、夫々、吸気弁によって
開閉されかつスワールを生成するようになった第１,第
２の吸気ポートが設けられたディーゼルエンジンの吸気
装置において、各気筒の第１の吸気ポートに吸気を分配
して供給する第１の吸気集合部と、各気筒の第２の吸気
ポートに吸気を分配して供給する第２の吸気集合部とが
設けられる一方、いずれか一方の吸気集合部に対して、
該吸気集合部にＥＧＲガスを導入するＥＧＲ機構と、該
吸気集合部への吸気供給経路を開閉する開閉弁とが設け
られ、かつ上記開閉弁を低負荷領域では全閉し、中負荷
領域では部分的に開き、高負荷領域では全開する開閉弁
制御手段が設けられていることを特徴とするディーゼル
エンジンの吸気装置を提供する。In order to achieve the above object, the first invention is the first and second inventions in which each cylinder is opened and closed by an intake valve and swirls are generated. In an intake system for a diesel engine provided with an intake port, a first intake collecting portion that distributes and supplies intake air to a first intake port of each cylinder and a second intake port of each cylinder that distributes intake air And a second intake air collecting portion to be supplied by
An EGR mechanism that introduces EGR gas into the intake collecting portion and an opening / closing valve that opens and closes an intake supply path to the intake collecting portion are provided, and the opening / closing valve is fully closed in a low load region, and in an intermediate load region. Provided is an intake system for a diesel engine, which is provided with an on-off valve control means which is partially opened and is fully opened in a high load region.
【０００６】第２の発明は、第１の発明にかかるディー
ゼルエンジンの吸気装置において、過給機が設けられ、
開閉弁制御手段が、吸気圧が排気圧よりも高いときには
開閉弁を部分的に開く負荷領域を中負荷領域外に拡張す
るようになっていることを特徴とするディーゼルエンジ
ンの吸気装置を提供する。A second aspect of the present invention is the diesel engine intake system according to the first aspect, further comprising a supercharger.
Provided is an intake system for a diesel engine, wherein the on-off valve control means is configured to expand a load region that partially opens the on-off valve to outside the medium load region when the intake pressure is higher than the exhaust pressure. .
【０００７】[0007]
【実施例】以下、本発明の実施例を具体的に説明する。
図１に示すように、４気筒ディーゼルエンジンＥの各気
筒１には、夫々、第１,第２吸気ポート２,３と、第１,
第２排気ポート４,５とが設けられている。ここで、第
１,第２吸気ポート２,３は、夫々後で説明するように、
基本的には同一回転方向のスワールを生成できるように
なっている。そして、各気筒１の第１吸気ポート２は夫
々第１独立吸気通路６と連通し、各気筒１の第２吸気ポ
ート３は第２独立吸気通路７と連通している。また、各
気筒１の第１,第２排気ポート４,５は夫々独立排気通路
８と連通している。EXAMPLES Examples of the present invention will be specifically described below.
As shown in FIG. 1, each cylinder 1 of the four-cylinder diesel engine E has a first intake port 2, 3 and a first intake port 2, 3, respectively.
Second exhaust ports 4, 5 are provided. Here, the first and second intake ports 2 and 3, respectively, will be described later.
Basically, swirls in the same rotation direction can be generated. The first intake port 2 of each cylinder 1 communicates with the first independent intake passage 6, and the second intake port 3 of each cylinder 1 communicates with the second independent intake passage 7. The first and second exhaust ports 4 and 5 of each cylinder 1 are in communication with the independent exhaust passage 8.
【０００８】そして、図２と図３とに示すように、エン
ジンＥの各気筒１においては、第１吸気ポート２を開閉
する第１吸気弁１１と、第２吸気ポート３を開閉する第
２吸気弁１２とが設けられ、エンジンＥは、第１,第２
吸気弁１１,１２が開かれたときに、第１,第２吸気ポー
ト２,３から燃焼室１３内に吸気(エア)を吸入し、この
吸気をピストン１４で圧縮して高圧・高温にした後、こ
の吸気中に燃料噴射弁１５から燃料を噴射し、この燃料
を高温の吸気で着火・燃焼させ、燃焼ガスを排気弁(図
示せず)が開かれたときに、第１,第２排気ポート４,５
を介して独立排気通路８に排出するようになっている。
なお、第１,第２吸気弁１１,１２は、吸気側カム機構１
６によって所定のタイミングで開閉されるようになって
いる。ここで、第１吸気ポート２は燃焼室１３のほぼ周
方向に向いて開口するタンゼンシャルポートであって、
燃焼室１３内に比較的弱いスワールを生成できるように
なっている。また、第２吸気ポート３は、開口部近傍が
ヘリカル状に形成されたヘリカルポートであって、燃焼
室１３内に比較的強いスワールを生成できるようになっ
ている。かかるスワールは、後で説明するように、エン
ジンＥの運転状態に応じて制御され、燃料の燃焼を緩慢
化して、ＮＯx発生量を低減する。As shown in FIGS. 2 and 3, in each cylinder 1 of the engine E, a first intake valve 11 for opening / closing the first intake port 2 and a second intake valve 11 for opening / closing the second intake port 3 are provided. The intake valve 12 is provided, and the engine E includes the first and second
When the intake valves 11 and 12 are opened, intake air (air) is sucked into the combustion chamber 13 from the first and second intake ports 2 and 3, and the intake air is compressed by the piston 14 to have high pressure and high temperature. After that, fuel is injected from the fuel injection valve 15 into the intake air, the fuel is ignited and burned by the high temperature intake air, and when the exhaust gas (not shown) opens the combustion gas, the first and second Exhaust port 4,5
It is designed to be discharged to the independent exhaust passage 8 via.
The first and second intake valves 11 and 12 are the intake side cam mechanism 1
It is designed to be opened and closed by 6 at a predetermined timing. Here, the first intake port 2 is a tangential port that opens in a substantially circumferential direction of the combustion chamber 13,
A relatively weak swirl can be generated in the combustion chamber 13. Further, the second intake port 3 is a helical port in which the vicinity of the opening is formed in a helical shape, and can generate a relatively strong swirl in the combustion chamber 13. As described later, the swirl is controlled according to the operating state of the engine E, slows the combustion of fuel, and reduces the NOx generation amount.
【０００９】再び、図１に示すように、エンジンＥに吸
気を供給するために吸気装置Ａが設けられ、この吸気装
置Ａの共通吸気通路２０には、吸気流れ方向にみて上流
側から順に、吸気中の塵を除去するエアクリーナ２１
と、排気ターボ式過給機２２のブロア２２aとが介設さ
れている。なお、過給機２２はエンジンＥの出力を高め
るために設けられている。そして、この共通吸気通路２
０は下流側に向かって、第１分岐吸気通路２３と、開閉
弁２５が介設された第２分岐吸気通路２４とに分岐して
いる。なお、後で説明するように、開閉弁２５はコント
ロールユニット３６によってその開度が制御されるよう
になっている。ここで、第１分岐吸気通路２３の下流端
は第１吸気集合部２６(サージタンク)に接続され、第２
分岐吸気通路２４の下流端は第２吸気集合部２８(サー
ジタンク)に接続されている。そして、第１吸気集合部
２６には前記した各第１独立吸気通路６の上流端が接続
され、第２吸気集合部２８には各第２独立吸気通路７の
上流端が接続されている。また、各独立排気通路８は排
気集合部３１で１つの共通排気通路３２に集合され、こ
の共通排気通路３２には、排気流れ方向にみて上流側か
ら順に、排気ターボ式過給機２２のタービン２２bと、
所定の触媒を用いた排気ガス浄化装置３３とが介設され
ている。Again, as shown in FIG. 1, an intake device A is provided for supplying intake air to the engine E, and the common intake passage 20 of this intake device A is arranged in order from the upstream side in the intake flow direction. Air cleaner 21 for removing dust in intake air
And a blower 22a of the exhaust turbo supercharger 22 are interposed. The supercharger 22 is provided to increase the output of the engine E. And this common intake passage 2
0 branches toward the downstream side into a first branch intake passage 23 and a second branch intake passage 24 in which an opening / closing valve 25 is provided. As will be described later, the opening degree of the opening / closing valve 25 is controlled by the control unit 36. Here, the downstream end of the first branch intake passage 23 is connected to the first intake collecting portion 26 (surge tank), and
The downstream end of the branch intake passage 24 is connected to the second intake collecting portion 28 (surge tank). The upstream ends of the first independent intake passages 6 described above are connected to the first intake collecting portion 26, and the upstream ends of the second independent intake passages 7 are connected to the second intake collecting portion 28. In addition, each of the independent exhaust passages 8 is collected by the exhaust collecting portion 31 into one common exhaust passage 32. In the common exhaust passage 32, the turbines of the exhaust turbocharger 22 are sequentially arranged from the upstream side in the exhaust flow direction. 22b,
An exhaust gas purifying device 33 using a predetermined catalyst is interposed.
【００１０】そして、吸気系にＥＧＲガスを導入するた
めに、一端が排気集合部３１に接続され、他端が第２吸
気集合部２８に接続されたＥＧＲ通路３４が設けられて
いる。このＥＧＲ通路３４には、これを開閉するＥＧＲ
制御弁３５が介設されている。ここで、ＥＧＲ制御弁３
５は、コントロールユニット３６によって、エンジンＥ
の運転状態に応じて開閉されるようになっている。かか
るＥＧＲガスは、燃焼温度を低下させ、ＮＯx発生量を
低減するために導入される。なお、コントロールユニッ
ト３６は、請求項１,２に記載された開閉弁制御手段に
相当する。In order to introduce the EGR gas into the intake system, an EGR passage 34 is provided, one end of which is connected to the exhaust collecting portion 31 and the other end of which is connected to the second intake collecting portion 28. The EGR passage 34 has an EGR for opening and closing the EGR passage 34.
A control valve 35 is provided. Here, the EGR control valve 3
The control unit 36 controls the engine 5
It is designed to be opened and closed according to the operating conditions of the. Such EGR gas is introduced in order to lower the combustion temperature and the NOx generation amount. The control unit 36 corresponds to the opening / closing valve control means described in claims 1 and 2.
【００１１】ところで、本実施例においては、エンジン
出力を高めつつ、ＮＯx発生量の低減を図るために、第
１,第２吸気ポート２,３によって生成されるスワール強
度と、ＥＧＲとが所定の方法で制御されるようになって
いるが、以下図１〜図３を適宜参照しつつ、これらの制
御方法を説明する。By the way, in this embodiment, in order to increase the engine output and reduce the NOx generation amount, the swirl intensity generated by the first and second intake ports 2 and 3 and the EGR are set to predetermined values. The method is controlled by a method, and these control methods will be described below with reference to FIGS.
【００１２】スワールの制御は、コントロールユニット
３６により、開閉弁２５の開度を変えることによって行
なわれる。なお、前記したとおり、特開昭６２−１７４
５３３号公報に開示されているような従来のスワール制
御手段では、各気筒毎に開閉弁を設けているので、開閉
弁を多数必要とするが、本案では開閉弁２５は１つです
むので、吸気装置Ａが簡素化される。The swirl is controlled by changing the opening degree of the opening / closing valve 25 by the control unit 36. In addition, as described above, JP-A-62-174
In the conventional swirl control means as disclosed in Japanese Patent No. 533, since an opening / closing valve is provided for each cylinder, a large number of opening / closing valves are required, but in the present invention, only one opening / closing valve 25 is required. The intake device A is simplified.
【００１３】図４に示すように、エンジン負荷が所定値
θ1以下であるような低負荷領域では(低負荷時)、開閉
弁２５が全閉される。この場合、第２吸気集合部２８に
は吸気が供給されないので、燃焼室１３へは第１吸気ポ
ート２だけから吸気が供給される。前記したとおり、第
１吸気ポート２はタンジェンシャルポートであるので、
燃焼室１３内に比較的弱いスワールが生成される(以
下、これを低スワールという)。As shown in FIG. 4, the on-off valve 25 is fully closed in a low load region where the engine load is equal to or less than the predetermined value θ 1 (when the load is low). In this case, since intake air is not supplied to the second intake air collecting portion 28, intake air is supplied to the combustion chamber 13 only from the first intake port 2. As described above, since the first intake port 2 is a tangential port,
A relatively weak swirl is generated in the combustion chamber 13 (hereinafter referred to as low swirl).
【００１４】エンジン負荷がθ1を超えかつ所定値θ2以
下であるような中負荷領域では(中負荷時)、開閉弁２５
が所定の開度で部分的に開かれる(以下、この状態を半
開という)。この場合、第２分岐吸気通路２４が開閉弁
２５によって絞られるので、第２吸気集合部２８への吸
気供給量は少なくなる。また、第２吸気集合部２８内の
吸気圧はかなり低くなる。したがって、第１吸気ポート
２から燃焼室１３へは、低負荷時と同様に吸気が供給さ
れ、この吸気は低負荷時と同程度のスワールを生成す
る。他方、第２吸気ポート３から燃焼室１３への吸気流
入量は少ない。ここで、第２吸気ポート３は前記したと
おりヘリカルポートであり、本来は比較的強いスワール
を生成するようになっているが、この場合は吸気量が少
ないので、第２吸気ポート３から燃焼室１３に流入する
吸気は弱いスワールしか生成しない。したがって、両吸
気ポート２,３から燃焼室１３に流入する吸気によっ
て、中程度のスワールが生成される(以下、これを中ス
ワールという)。In the medium load region where the engine load exceeds θ 1 and is equal to or smaller than the predetermined value θ 2 (during medium load), the on-off valve 25
Is partially opened at a predetermined opening (hereinafter, this state is called half-open). In this case, since the second branch intake passage 24 is throttled by the opening / closing valve 25, the amount of intake air supplied to the second intake collecting portion 28 is reduced. Further, the intake pressure in the second intake collecting portion 28 becomes considerably low. Therefore, the intake air is supplied from the first intake port 2 to the combustion chamber 13 in the same manner as when the load is low, and this intake air produces a swirl of the same degree as when the load is low. On the other hand, the amount of intake air flowing into the combustion chamber 13 from the second intake port 3 is small. Here, the second intake port 3 is a helical port as described above and originally generates a relatively strong swirl. In this case, however, the intake amount is small, so the second intake port 3 is connected to the combustion chamber. The intake air flowing into 13 produces only a weak swirl. Therefore, a medium swirl is generated by the intake air flowing into the combustion chamber 13 from both intake ports 2 and 3 (hereinafter, this is referred to as a medium swirl).
【００１５】エンジン負荷がθ2を超えるような高負荷
領域では(高負荷時)、開閉弁２５が全開される。この場
合、第２吸気ポート３から燃焼室１３に通常どおりの吸
気が流入し、この吸気によって燃焼室１３内に比較的強
いスワールが生成される。なお、第１吸気ポート２から
の吸気によって、低負荷と同程度のスワールが生成され
る。したがって、両吸気ポート２,３によって、燃焼室
１３内には強いスワールが生成される(以下、これを高
スワールという)。In a high load region where the engine load exceeds θ 2 (during high load), the on-off valve 25 is fully opened. In this case, the normal intake air flows into the combustion chamber 13 from the second intake port 3, and a relatively strong swirl is generated in the combustion chamber 13 by this intake air. By the intake air from the first intake port 2, a swirl of the same level as a low load is generated. Therefore, a strong swirl is generated in the combustion chamber 13 by both the intake ports 2 and 3 (hereinafter, this is referred to as high swirl).
【００１６】つまり、低負荷時には低スワールが生成さ
れ、中負荷時には中スワールが生成され、高負荷時には
高スワールが生成されることになる。一般に、スワール
が強いほど、燃焼室１３内の吸気が層状化され、燃料が
緩慢燃焼して燃焼温度の過剰な上昇が抑制され、ＮＯx
発生量が低減される。しかしながら、ディーゼルエンジ
ンにおいて、低負荷時すなわち燃焼噴射量の少ないとき
には、スワールが強過ぎると、吸気がリーンとなり、着
火しにくくなる。そして、この後着火したときには燃料
が急燃焼するので、かえって燃焼温度が高くなり、ＮＯ
x発生量が増えてしまう。このため、エンジン負荷が低
いときにはスワールを弱めるようにしているわけであ
る。このように、エンジン負荷に応じてスワール強度が
制御され、ＮＯx発生量が低減される。That is, a low swirl is generated when the load is low, a medium swirl is generated when the load is medium, and a high swirl is generated when the load is high. In general, the stronger the swirl, the more stratified the intake air in the combustion chamber 13, the slower combustion of the fuel, and the suppression of the excessive rise of the combustion temperature.
The amount generated is reduced. However, in the diesel engine, when the load is low, that is, when the combustion injection amount is small, if the swirl is too strong, the intake air becomes lean, and it becomes difficult to ignite. Then, when ignition occurs after this, the fuel rapidly burns, so the combustion temperature rises and NO
x The amount generated increases. Therefore, the swirl is weakened when the engine load is low. In this way, the swirl strength is controlled according to the engine load, and the NOx generation amount is reduced.
【００１７】ＥＧＲ制御は、コントロールユニット３６
により、ＥＧＲ制御弁３５を開閉することによって行な
われる。本実施例では、基本的には、エンジン負荷がθ
1〜θ2である中負荷領域でＥＧＲ制御弁３５を開き、吸
気系にＥＧＲガスを導入するようにしている。なお、低
負荷領域でもＥＧＲ制御弁２５を開いて、ＥＧＲガスを
燃焼室１３に導入するようにしてもよい。ただし、この
場合は開閉弁２５が閉じられているので、第２吸気ポー
ト３から燃焼室１３へはＥＧＲガスしか流入しない。一
般的には、ＥＧＲガス量が多いほど、燃焼温度が抑制さ
れ、ＮＯx発生量が低減される。しかしながら、高負荷
時には燃料噴射量が多いので、ＥＧＲガスを導入すると
その分だけ、燃料の燃焼に必要なエア(酸素)が不足し、
エンジン出力の低下を招くとともに、不完全燃焼による
スモークが発生する。そこで、負荷がθ2を超える高負
荷領域ではＥＧＲガスの導入を行わないようにしてい
る。また、本実施例では、負荷がθ1以下の低負荷領域
では、第２吸気集合部２８にＥＧＲガスを導入すると、
第２吸気ポート３から燃焼室１３内へはＥＧＲガスしか
供給されなくなる。このため、低負荷領域ではＥＧＲガ
スの導入を行なわないようにしている。このように、基
本的には、エンジン負荷に応じて吸気系にＥＧＲガスが
供給され、燃焼室１３内の燃焼温度の不必要な上昇が防
止され、ＮＯx発生量が低減される。The EGR control is performed by the control unit 36.
Is performed by opening and closing the EGR control valve 35. In this embodiment, basically, the engine load is θ
The EGR control valve 35 is opened in the medium load range of 1 to θ 2 so that EGR gas is introduced into the intake system. The EGR control valve 25 may be opened even in the low load region to introduce the EGR gas into the combustion chamber 13. However, in this case, since the on-off valve 25 is closed, only EGR gas flows into the combustion chamber 13 from the second intake port 3. Generally, as the EGR gas amount increases, the combustion temperature is suppressed and the NOx generation amount decreases. However, since the fuel injection amount is large at high load, when EGR gas is introduced, the amount of air (oxygen) required for fuel combustion is correspondingly insufficient,
The engine output is reduced, and smoke is generated due to incomplete combustion. Therefore, the EGR gas is not introduced in the high load region where the load exceeds θ 2 . Further, in this embodiment, when the EGR gas is introduced into the second intake air collecting portion 28 in the low load region where the load is θ 1 or less,
Only EGR gas is supplied from the second intake port 3 into the combustion chamber 13. Therefore, the EGR gas is not introduced in the low load region. As described above, basically, EGR gas is supplied to the intake system according to the engine load, an unnecessary increase in the combustion temperature in the combustion chamber 13 is prevented, and the NOx generation amount is reduced.
【００１８】ところで、本実施例では、エンジンＥの出
力を高めるために、吸気装置Ａに排気ターボ式過給機２
２が設けられている。このため、図５に示すように、エ
ンジン回転数がＮ1を超える高回転領域では、吸気圧力
が排気圧力より高くなる。したがって、前記したとお
り、普通の過給機付エンジンでは、かかる高回転領域で
ＥＧＲ弁を開くと、吸気が排気系に逆流することにな
る。しかしながら、本実施例では、前記したとおり、開
閉弁２５が半開状態にあるときには、第２吸気集合部２
８内の吸気圧が低下し、この吸気圧が排気圧力より低く
なる。つまり、開閉弁２５を半開状態にすることによっ
て、吸気圧力が排気圧力より高い領域でもＥＧＲガスを
吸気系に導入できるわけである。図６に示すように、本
実施例では、回転数にかかわりなくエンジン負荷がθ1
〜θ2の中負荷領域でＥＧＲガスが導入されるが、この
中で、斜線を引いた部分が、従来の過給機付エンジンで
はＥＧＲガスの導入が不可能な領域である。なお、過給
機として機械式過給機を用いた場合は、低回転領域から
吸気圧力が排気圧力より高くなることがあるが、本発明
によれば、このような機械式過給機が設けられている場
合でも、開閉弁２５を半開状態にすることによっていつ
でも吸気系にＥＧＲガスを導入できることになる。By the way, in this embodiment, in order to increase the output of the engine E, the intake turbocharger 2 is installed in the intake system A.
Two are provided. Therefore, as shown in FIG. 5, the intake pressure becomes higher than the exhaust pressure in the high rotation speed region where the engine speed exceeds N 1 . Therefore, as described above, in an ordinary engine with a supercharger, when the EGR valve is opened in such a high rotation range, intake air flows back into the exhaust system. However, in the present embodiment, as described above, when the open / close valve 25 is in the half-opened state, the second intake collecting portion 2
The intake pressure in 8 drops, and this intake pressure becomes lower than the exhaust pressure. That is, by opening the open / close valve 25 in the half-opened state, the EGR gas can be introduced into the intake system even in a region where the intake pressure is higher than the exhaust pressure. As shown in FIG. 6, in this embodiment, the engine load is θ 1 regardless of the number of revolutions.
Although the EGR gas is introduced in the medium load region of? 2 , the hatched portion is a region in which the EGR gas cannot be introduced in the conventional engine with a supercharger. When a mechanical supercharger is used as the supercharger, the intake pressure may become higher than the exhaust pressure in the low rotation range, but according to the present invention, such a mechanical supercharger is provided. Even in such a case, the EGR gas can be introduced into the intake system at any time by opening the open / close valve 25 in the half-opened state.
【００１９】前記したとおり、基本的には、負荷がθ2
を超える高負荷領域では、吸気系にＥＧＲガスを導入す
ると、出力低下あるいはスモークが発生する。このた
め、かかる高負荷領域ではＥＧＲガスを吸気系に導入し
ないようにしているが、エンジン回転数がＮ1を超える
高回転領域では、吸気の圧力が高く、燃焼室１３に供給
される吸気量が多くなる。このため、Ｎ1を超える高回
転領域では、エアが十分にあるので高負荷時に、ＥＧＲ
ガスを導入しても出力低下あるいはスモークが発生しに
くい。As described above, the load is basically θ 2
In a high load region exceeding 0, output reduction or smoke occurs when EGR gas is introduced into the intake system. Therefore, the EGR gas is not introduced into the intake system in the high load region, but in the high rotation region where the engine speed exceeds N 1 , the intake pressure is high and the amount of intake air supplied to the combustion chamber 13 is high. Will increase. For this reason, in the high rotation region exceeding N 1 , there is sufficient air, so at high load, EGR
Even if gas is introduced, the output is less likely to decrease or smoke is unlikely to occur.
【００２０】そこで、図７に示すように、回転数がＮ1
を超える高回転領域では、開閉弁２５を半開から全開に
切り替えるエンジン負荷をθ2より高い所定値βに変更
してもよい。このようにすれば、より高負荷領域までＮ
Ｏx発生量を低減することができる。また、かかる高回
転領域では、燃焼室内の吸気圧が高く、したがって酸素
濃度が高くなり燃料が燃焼しやすくなる。したがって、
スワールが多少強くなっても着火性が悪くならない。そ
こで、Ｎ1を超える高回転領域では、開閉弁２を全閉か
ら半開に切り替えるエンジン負荷をθ1より低い所定値
αに変更してもよい。このようにすれば、より低負荷領
域までＮＯx発生量を低減することができる。Therefore, as shown in FIG. 7, the rotation speed is N 1
In a high rotation region exceeding 0, the engine load for switching the open / close valve 25 from half open to full open may be changed to a predetermined value β higher than θ 2 . By doing this, N
The amount of Ox generated can be reduced. Further, in such a high rotation speed region, the intake pressure in the combustion chamber is high, and therefore the oxygen concentration is high and the fuel is likely to burn. Therefore,
The ignitability does not deteriorate even if the swirl becomes slightly stronger. Therefore, in the high rotation speed region exceeding N 1 , the engine load for switching the open / close valve 2 from fully closed to half open may be changed to a predetermined value α lower than θ 1 . By doing so, the NOx generation amount can be reduced to a lower load region.
【００２１】[0021]
【発明の作用・効果】第１の発明によれば、スワールの
強度を切り替える開閉弁が１つですむので、各気筒毎に
開閉弁を設けた従来の吸気装置に比べて、吸気装置が簡
素化されコストダウンが図れる。また、高負荷時には燃
焼室内に高スワールが生成されるので、燃料の燃焼が緩
慢化され、燃焼温度の不必要な上昇が防止され、ＮＯx
発生量が低減される。また、一般に過剰なスワールは着
火性を低下させるが、中負荷時にはスワールが弱めら
れ、低負荷時にはさらに弱められるので、燃料の着火性
が低下せず、着火遅れに起因する燃料の急燃焼が防止さ
れ、ＮＯx発生量が低減される。さらに、中負荷領域と
低負荷領域とでは、吸気系へのＥＧＲガスの導入が容易
に行なえるので、燃焼温度が低下しＮＯx発生量が低減
される。かつ、エンジンに過給機が設けられた場合に
は、中負荷領域では、吸気圧力が排気圧力より高いとき
でも、ＥＧＲガスを吸気系に導入することができ、ＮＯ
x発生量が低減される。According to the first aspect of the present invention, since only one opening / closing valve for switching the strength of the swirl is required, the intake device is simpler than the conventional intake device having an opening / closing valve for each cylinder. And cost reduction can be achieved. Further, since a high swirl is generated in the combustion chamber at the time of high load, the combustion of fuel is slowed down, an unnecessary increase in combustion temperature is prevented, and NOx is reduced.
The amount generated is reduced. In general, excessive swirl lowers the ignitability, but the swirl is weakened at medium load and further weakened at low load, so the ignitability of fuel does not decrease and rapid combustion of fuel due to ignition delay is prevented. As a result, the amount of NOx generated is reduced. Further, in the medium load region and the low load region, since the EGR gas can be easily introduced into the intake system, the combustion temperature is lowered and the NOx generation amount is reduced. In addition, when the engine is provided with the supercharger, the EGR gas can be introduced into the intake system in the medium load region even when the intake pressure is higher than the exhaust pressure.
The amount of x generated is reduced.
【００２２】第２の発明によれば、基本的には、第１の
発明と同様の作用・効果が得られる。さらに、吸気圧力
が排気圧力より高くなる回転領域で、ＥＧＲガスを導入
する負荷領域が拡張されているので、ＮＯx発生量の低
減効果が一層高められる。According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, since the load region for introducing the EGR gas is expanded in the rotation region where the intake pressure is higher than the exhaust pressure, the effect of reducing the NOx generation amount is further enhanced.
【図１】本発明の実施例を示すディーゼルエンジンとそ
の吸気装置のシステム構成図である。FIG. 1 is a system configuration diagram of a diesel engine and an intake device thereof showing an embodiment of the present invention.
【図２】図１に示すエンジンの吸気ポートまわりの立面
断面説明図である。FIG. 2 is an elevational cross-sectional explanatory view around an intake port of the engine shown in FIG.
【図３】図１に示すエンジンの吸気ポートまわりの平面
断面説明図である。FIG. 3 is an explanatory plan cross-sectional view around an intake port of the engine shown in FIG.
【図４】開閉弁の開閉特性を、エンジン負荷とエンジン
回転数とに対してあらわした図である。FIG. 4 is a diagram showing an opening / closing characteristic of an on-off valve with respect to an engine load and an engine speed.
【図５】吸気圧力と排気圧力の、エンジン回転数に対す
る特性を示す図である。FIG. 5 is a diagram showing characteristics of intake pressure and exhaust pressure with respect to engine speed.
【図６】ＥＧＲガスの導入領域を、エンジン負荷とエン
ジン回転数とに対してあらわした図である。FIG. 6 is a diagram showing an EGR gas introduction region with respect to an engine load and an engine speed.
【図７】吸気圧力が排気圧力より高い回転領域で、ＥＧ
Ｒガス導入領域を拡張した図６と同様の図である。FIG. 7 is a graph showing EG in a rotation region where the intake pressure is higher than the exhaust pressure.
It is the same figure as FIG. 6 which expanded the R gas introduction area.
Ａ…吸気装置 Ｅ…ディーゼルエンジン ２,３…第１,第２吸気ポート １１,１２…第１,第２吸気弁 ２２…排気ターボ過給機 ２５…開閉弁 ２６…第１吸気集合部 ２８…第２吸気集合部 ３４…ＥＧＲ通路 ３５…ＥＧＲ制御弁 ３６…コントロールユニット A ... Intake device E ... Diesel engine 2, 3 ... First and second intake ports 11, 12 ... First and second intake valves 22 ... Exhaust turbocharger 25 ... Open / close valve 26 ... 1st intake collecting part 28 ... 2nd intake collecting part 34 ... EGR passage 35 ... EGR control valve 36 ... Control unit
Claims (2)
れかつスワールを生成するようになった第１,第２の吸
気ポートが設けられたディーゼルエンジンの吸気装置に
おいて、 各気筒の第１の吸気ポートに吸気を分配して供給する第
１の吸気集合部と、各気筒の第２の吸気ポートに吸気を
分配して供給する第２の吸気集合部とが設けられる一
方、いずれか一方の吸気集合部に対して、該吸気集合部
にＥＧＲガスを導入するＥＧＲ機構と、該吸気集合部へ
の吸気供給経路を開閉する開閉弁とが設けられ、かつ上
記開閉弁を低負荷領域では全閉し、中負荷領域では部分
的に開き、高負荷領域では全開する開閉弁制御手段が設
けられていることを特徴とするディーゼルエンジンの吸
気装置。1. An intake system for a diesel engine, wherein each cylinder is provided with first and second intake ports which are opened and closed by an intake valve and are adapted to generate swirl, respectively. A first intake collecting portion that distributes and supplies the intake air to the intake ports and a second intake collecting portion that distributes and supplies the intake air to the second intake ports of each cylinder are provided. An EGR mechanism that introduces EGR gas into the intake collecting portion and an opening / closing valve that opens and closes an intake supply path to the intake collecting portion are provided for the intake collecting portion, and the opening / closing valve is provided in the low load region. An intake device for a diesel engine, which is provided with an on-off valve control means that is closed, partially opened in a medium load region, and fully opened in a high load region.
気装置において、 過給機が設けられ、開閉弁制御手段が、吸気圧が排気圧
よりも高いときには開閉弁を部分的に開く負荷領域を中
負荷領域外に拡張するようになっていることを特徴とす
るディーゼルエンジンの吸気装置。2. The intake system for a diesel engine according to claim 1, wherein a supercharger is provided, and the opening / closing valve control means sets a load region that partially opens the opening / closing valve when the intake pressure is higher than the exhaust pressure. An intake device for a diesel engine, which is adapted to extend outside the load range.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17106591A JP3315416B2 (en) | 1991-07-11 | 1991-07-11 | Diesel engine intake system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17106591A JP3315416B2 (en) | 1991-07-11 | 1991-07-11 | Diesel engine intake system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0518254A true JPH0518254A (en) | 1993-01-26 |
| JP3315416B2 JP3315416B2 (en) | 2002-08-19 |
Family
ID=15916401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17106591A Expired - Fee Related JP3315416B2 (en) | 1991-07-11 | 1991-07-11 | Diesel engine intake system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3315416B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2768774A1 (en) | 1997-09-22 | 1999-03-26 | Nissan Diesel Motor Company | INTERNAL COMBUSTION ENGINE INTAKE APPARATUS |
| EP1081351A2 (en) | 1999-08-31 | 2001-03-07 | Honda Giken Kogyo Kabushiki Kaisha | Air intake system for internal combustion engine |
| US7311775B2 (en) | 2004-02-09 | 2007-12-25 | Sumco Corporation | Method for heat-treating silicon wafer and silicon wafer |
| FR2915239A1 (en) * | 2007-04-17 | 2008-10-24 | Renault Sas | Internal combustion engine i.e. oil engine, exhaust gas recirculation rate, estimating method for motor vehicle, involves calculating exhaust gas recirculation rate of engine according to air flow and temperature in upstream of valves |
| WO2011125208A1 (en) * | 2010-04-08 | 2011-10-13 | トヨタ自動車株式会社 | Combustion control device for internal combustion engine |
-
1991
- 1991-07-11 JP JP17106591A patent/JP3315416B2/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2768774A1 (en) | 1997-09-22 | 1999-03-26 | Nissan Diesel Motor Company | INTERNAL COMBUSTION ENGINE INTAKE APPARATUS |
| EP1081351A2 (en) | 1999-08-31 | 2001-03-07 | Honda Giken Kogyo Kabushiki Kaisha | Air intake system for internal combustion engine |
| EP1081351A3 (en) * | 1999-08-31 | 2002-03-06 | Honda Giken Kogyo Kabushiki Kaisha | Air intake system for internal combustion engine |
| US7311775B2 (en) | 2004-02-09 | 2007-12-25 | Sumco Corporation | Method for heat-treating silicon wafer and silicon wafer |
| FR2915239A1 (en) * | 2007-04-17 | 2008-10-24 | Renault Sas | Internal combustion engine i.e. oil engine, exhaust gas recirculation rate, estimating method for motor vehicle, involves calculating exhaust gas recirculation rate of engine according to air flow and temperature in upstream of valves |
| WO2011125208A1 (en) * | 2010-04-08 | 2011-10-13 | トヨタ自動車株式会社 | Combustion control device for internal combustion engine |
| JPWO2011125208A1 (en) * | 2010-04-08 | 2013-07-08 | トヨタ自動車株式会社 | Combustion control device for internal combustion engine |
| JP5278600B2 (en) * | 2010-04-08 | 2013-09-04 | トヨタ自動車株式会社 | Combustion control device for internal combustion engine |
| US9097190B2 (en) | 2010-04-08 | 2015-08-04 | Toyota Jidosha Kabushiki Kaisha | Combustion control apparatus for an internal combustion engine |
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| JP3315416B2 (en) | 2002-08-19 |
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