JPH0882234A - Intake device for engine - Google Patents

Intake device for engine

Info

Publication number
JPH0882234A
JPH0882234A JP6219065A JP21906594A JPH0882234A JP H0882234 A JPH0882234 A JP H0882234A JP 6219065 A JP6219065 A JP 6219065A JP 21906594 A JP21906594 A JP 21906594A JP H0882234 A JPH0882234 A JP H0882234A
Authority
JP
Japan
Prior art keywords
air
fuel ratio
fuel
intake
egr
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.)
Pending
Application number
JP6219065A
Other languages
Japanese (ja)
Inventor
Toshihide Yamamoto
寿英 山本
Tsugio Hatsuhira
次男 服平
Masashi Maruhara
正志 丸原
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mazda Motor Corp
Original Assignee
Mazda Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mazda Motor Corp filed Critical Mazda Motor Corp
Priority to JP6219065A priority Critical patent/JPH0882234A/en
Publication of JPH0882234A publication Critical patent/JPH0882234A/en
Pending legal-status Critical Current

Links

Classifications

    • 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

Landscapes

  • Fuel-Injection Apparatus (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Abstract

PURPOSE: To significantly reduce NOx in exhaust gas while avoiding the misfire of an engine, and ensure a satisfactory fuel economy. CONSTITUTION: While an air-fuel mixture is formed in an air-fuel mixture feed port 57 different from intake ports 16, 18, and supplied into a combustion chamber 14, a swirl is generated in the combustion chamber 14, whereby the air-fuel mixture is laminated to enhance combustibility. The EGR ratio through an EGR pipe 48 is set to 20% or more, and the air fuel ratio is set to 16-20 at least in low load operating area.

Description

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

【０００１】[0001]

【産業上の利用分野】本発明は、通常の吸気ポートとは
別に、加圧エアと燃料との混合により混合気を形成して
燃焼室内に供給するための混合気供給ポートを備えたエ
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 an engine provided with an air-fuel mixture supply port for forming an air-fuel mixture by mixing pressurized air and fuel and supplying the mixture into a combustion chamber, in addition to an ordinary intake port. The present invention relates to an intake device.

【０００２】[0002]

【従来の技術】従来、燃料の気化・霧化を促進して混合
気を成層化する手段として、例えば特開平５−３９７２
０号公報に示される装置が知られている。この装置は、
吸気ポートからの吸気で燃焼室内にスワールを生成する
一方、吸気ポートとは別に混合気供給ポートを燃焼室内
に開口させ、この混合気供給ポートを所定容積をもつ閉
空間に連通させるとともに、この閉空間にインジェクタ
を設け、上記混合気供給ポートをタイミング弁によって
排気行程の前半及び吸気行程の後半で開くようにしたも
のである。この装置によれば、排気行程後半に混合気供
給ポート内に取り込まれた排ガス（加圧ガス）とインジ
ェクタからの燃料とが上記閉空間で混合されて混合気が
形成され、この混合気が上記スワールの中心部に供給さ
れて成層化されることにより燃焼性が高められる。2. Description of the Related Art Conventionally, as means for promoting the vaporization and atomization of fuel to stratify the air-fuel mixture, for example, JP-A-5-3972 is known.
The device shown in Japanese Patent No. 0 is known. This device
While the swirl is generated in the combustion chamber by the intake air from the intake port, an air-fuel mixture supply port is opened in the combustion chamber separately from the intake port, and this air-fuel mixture supply port is communicated with a closed space having a predetermined volume and An injector is provided in the space, and the air-fuel mixture supply port is opened by a timing valve in the first half of the exhaust stroke and the second half of the intake stroke. According to this device, the exhaust gas (pressurized gas) taken into the air-fuel mixture supply port in the latter half of the exhaust stroke and the fuel from the injector are mixed in the closed space to form the air-fuel mixture. Combustibility is enhanced by being supplied to the central part of the swirl and stratified.

【０００３】そして、上記公報では、上記混合気成層化
による燃焼性向上を利用して、良好な希薄燃焼を実現
し、燃費改善を図っている。In the above publication, the improvement of combustibility due to the stratification of the air-fuel mixture is utilized to realize favorable lean combustion and improve fuel efficiency.

【０００４】[0004]

【発明が解決しようとする課題】上記公報では、希薄燃
焼により燃費改善を狙っているが、より一層の燃費節減
が要望されている。In the above publication, the fuel consumption is improved by the lean combustion, but further fuel consumption saving is demanded.

【０００５】また近年は、排ガス中に含まれるＮＯｘ量
の規制が厳しく、ＮＯｘ低減が重要な課題となってお
り、その低減手段としては、排ガス還流（以下、ＥＧＲ
と称する）が有効であるが、上記公報のように、燃費を
改善するために空燃比を大きくリーン側に設定すると、
燃焼性が低下するためにＥＧＲ率の増加は著しく制限さ
れ、十分なＮＯｘ低減効果は期待できなくなる。Further, in recent years, the amount of NOx contained in exhaust gas is strictly regulated, and reducing NOx has become an important issue. As a means for reducing NOx, exhaust gas recirculation (hereinafter referred to as EGR) is used.
Is effective), but if the air-fuel ratio is set to a large lean side in order to improve fuel efficiency as in the above publication,
Since the combustibility deteriorates, the increase in the EGR rate is significantly limited, and a sufficient NOx reduction effect cannot be expected.

【０００６】本発明は、このような事情に鑑み、燃費を
大幅に改善し、かつ、エンジンの失火を避けながら多量
のＥＧＲを可能にして排ガス中のＮＯｘを低減できるエ
ンジンの吸気装置を提供することを目的とする。In view of the above circumstances, the present invention provides an intake system for an engine, which significantly improves fuel economy and enables a large amount of EGR while avoiding engine misfire to reduce NOx in exhaust gas. The purpose is to

【０００７】[0007]

【課題を解決するための手段】本発明者等は、上記課題
を解決すべく研究を重ねた結果、混合気成層化を行いな
がらＥＧＲを行い、かつ空燃比をわずかにリーン側の特
定範囲に設定することにより、燃費が大幅に改善される
ことを突き止めた。Means for Solving the Problems As a result of repeated research to solve the above problems, the inventors of the present invention have performed EGR while performing stratification of an air-fuel mixture and have an air-fuel ratio slightly within a specific range on the lean side. We have found that the fuel economy can be significantly improved by setting it.

【０００８】本発明は、このような研究の結果、なされ
たものであり、吸気ポートとは別に、加圧エアと燃料と
の混合により混合気を形成して燃焼室内に供給するため
の混合気供給ポートを備え、この混合気供給ポートの上
記燃焼室内に対する開口期間が吸気行程後半から圧縮行
程にかけての期間に設定されたエンジンの吸気装置にお
いて、上記吸気ポートをこの吸気ポートからの吸気によ
り燃焼室内にスワールが生成されるように配置し、上記
混合気供給ポートを点火プラグ近傍のボア中心部に対し
て略シリンダ中心線方向に開口させるとともに、上記吸
気ポートに排ガスを還流させる排ガス還流手段を備え、
少なくとも低負荷運転領域において上記混合気供給によ
る筒内空燃比を１６以上２０以下に設定し、上記排ガス
還流手段による排ガス還流率を２０％以上に設定したも
のである（請求項１）。The present invention has been made as a result of such research, and is a mixture for forming a mixture by mixing pressurized air and fuel and supplying the mixture into the combustion chamber, separately from the intake port. In an intake system for an engine, which is provided with a supply port and whose opening period of the mixture supply port to the combustion chamber is set to a period from the latter half of the intake stroke to the compression stroke, the intake port is provided with intake air from the intake port. Is arranged so that swirl is generated, the mixture gas supply port is opened substantially in the direction of the cylinder center line with respect to the center of the bore near the ignition plug, and exhaust gas recirculation means for recirculating exhaust gas to the intake port is provided. ,
At least in the low load operation region, the in-cylinder air-fuel ratio by the mixture supply is set to 16 or more and 20 or less, and the exhaust gas recirculation rate by the exhaust gas recirculation means is set to 20% or more (claim 1).

【０００９】この装置において、上記低負荷運転領域よ
りも高負荷側の高負荷運転領域では上記筒内空燃比を略
理論空燃比に設定するようにしてもよい（請求項２）。In this device, the in-cylinder air-fuel ratio may be set to a substantially stoichiometric air-fuel ratio in the high-load operating region on the higher load side than the low-load operating region (claim 2).

【００１０】また、上記装置では、排気通路に三元触媒
や理論空燃比に加えてリーン空燃比でもＮＯｘ浄化性能
をもつ触媒を設けるのが、より好ましい（請求項３〜
５）。Further, in the above apparatus, it is more preferable to provide a catalyst having NOx purification performance with a lean air-fuel ratio in addition to the three-way catalyst and the theoretical air-fuel ratio in the exhaust passage.
5).

【００１１】[0011]

【作用】上記装置によれば、混合気供給ポートからの混
合気供給とスワール生成とにより燃焼室内で混合気が良
好に成層化されるため、ＥＧＲ率を２０％以上に設定し
ながらも点火プラグの周囲に十分な量の混合気を確保で
き、エンジンの失火を避けながらヘビーＥＧＲでＮＯｘ
発生を抑えることができる。しかも、このような混合気
成層化を少なくとも低負荷運転領域において１６〜２０
の空燃比で行い、かつＥＧＲを同時実行すると、このＥ
ＧＲによりポンピングロスが低減され、また吸気温度が
上昇するのに加え、後述のように燃焼が活発化されて熱
効率が高くなり、ＥＧＲを行わない場合よりも燃費が大
幅に向上する。According to the above device, since the air-fuel mixture is favorably stratified in the combustion chamber by the air-fuel mixture supply from the air-fuel mixture supply port and the swirl generation, the spark plug is set while the EGR rate is set to 20% or more. A sufficient amount of air-fuel mixture can be secured around the engine, avoiding engine misfire and heavy EGR for NOx.
Occurrence can be suppressed. Moreover, such stratification of the air-fuel mixture is performed at least in the low load operation region for 16 to 20 times.
If the air-fuel ratio of
In addition to the pumping loss being reduced by the GR and the intake air temperature being raised, the combustion is activated and the thermal efficiency is increased as will be described later, and the fuel efficiency is significantly improved as compared with the case where the EGR is not performed.

【００１２】ここで、請求項２記載の装置では、上記低
負荷運転領域よりも高負荷側の高負荷運転領域では上記
筒内空燃比を略理論空燃比に設定しているので、高トル
ク要求を満たすことができ、しかも、空燃比を上記１６
〜２０の範囲よりも下げる分、燃焼を緩慢にしてＮＯｘ
発生をより抑えることが可能である。According to the second aspect of the present invention, since the in-cylinder air-fuel ratio is set to a substantially stoichiometric air-fuel ratio in the high-load operating region on the higher load side than the low-load operating region, a high torque request is required. And the air-fuel ratio is 16
The combustion is slowed down by the amount lower than the range of 20 to NOx.
It is possible to further suppress the occurrence.

【００１３】請求項３記載の装置では、排気通路に設け
られた三元触媒により、エミッションがさらに改善され
る。特に、空燃比１６〜２０の領域では、ＨＣが大幅に
低減される。In the device according to the third aspect, the emission is further improved by the three-way catalyst provided in the exhaust passage. In particular, HC is significantly reduced in the region where the air-fuel ratio is 16 to 20.

【００１４】さらに、上記三元触媒を請求項２の装置、
すなわち、高負荷運転領域で略理論空燃比とする装置に
設ければ（請求項４）、高負荷側では上記ＨＣに加えて
ＣＯ、及びＮＯｘも大幅に低減させることができ、エミ
ッションはさらに改善される。Further, the three-way catalyst is the device according to claim 2,
That is, if provided in a device that achieves a substantially stoichiometric air-fuel ratio in the high load operation region (Claim 4), CO and NOx can be significantly reduced in addition to the HC on the high load side, and emissions are further improved. To be done.

【００１５】また、請求項５記載のように理論空燃比に
加えてリーン空燃比でもＮＯｘ浄化性能をもつ触媒を用
いれば、上記のように空燃比を１６〜２０に設定しても
触媒でさらにＮＯｘを低減させることができる。Further, if a catalyst having NOx purification performance with a lean air-fuel ratio in addition to the stoichiometric air-fuel ratio as described in claim 5 is used, even if the air-fuel ratio is set to 16 to 20 as described above, the catalyst is further improved. NOx can be reduced.

【００１６】[0016]

【実施例】本発明の一実施例を図面に基づいて説明す
る。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

【００１７】図１に示すエンジン本体１０の各シリンダ
内には、ピストン１２が昇降可能に収納され、その上方
に燃焼室１４が形成されている。この燃焼室１４内に
は、第１吸気ポート１６、第２吸気ポート１８、及び２
つの排気ポート２０が開口している。図２に示すよう
に、第１吸気ポート１６及び第２吸気ポート１８は中心
部を境に一方の側（図１，２では左側）に配され、両排
気ポート２０は他方の側（図１，２では右側）に配され
ており、ボア略中心部には点火プラグ２６が配設されて
いる。両吸気ポート１６，１８は、それぞれ吸気弁２２
の作動により開閉され、両排気ポート２０は、それぞれ
排気弁２４の作動により開閉されるようになっている。In each cylinder of the engine body 10 shown in FIG. 1, a piston 12 is housed so as to be able to move up and down, and a combustion chamber 14 is formed above it. In the combustion chamber 14, the first intake port 16, the second intake port 18, and 2
Two exhaust ports 20 are open. As shown in FIG. 2, the first intake port 16 and the second intake port 18 are arranged on one side (left side in FIGS. 1 and 2) with the center part as a boundary, and both exhaust ports 20 are arranged on the other side (FIG. 1). , 2 on the right side), and an ignition plug 26 is provided at the approximate center of the bore. Both intake ports 16 and 18 have intake valves 22 respectively.
The exhaust port 20 is opened and closed by the operation of the exhaust valve 24.

【００１８】第１吸気ポート１６及び第２吸気ポート１
８には、それぞれ第１吸気管２８及び第２吸気管３０が
接続され、両吸気管２８，３０は共通のサージタンク３
２に接続されている。このサージタンク３２上流側の独
立吸気管には、エアクリーナー３４やスロットル弁３６
が配設されている。上記第２吸気ポート１８の途中に
は、スワールコントロール弁３８が設けられ、アクチュ
エータ４０により開閉駆動されるようになっている。第
１吸気ポート１６は、第２吸気ポート１８よりも水平に
近い方向から燃焼室１４に入射しており、上記スワール
コントロール弁３８が閉じた状態で第１吸気ポート１６
からの吸気により燃焼室１４内でのスワール（横スワー
ル）生成が促されるようになっている。First intake port 16 and second intake port 1
A first intake pipe 28 and a second intake pipe 30 are connected to each other, and both intake pipes 28 and 30 are common to the surge tank 3
Connected to 2. An air cleaner 34 and a throttle valve 36 are provided in the independent intake pipe upstream of the surge tank 32.
Is provided. A swirl control valve 38 is provided in the middle of the second intake port 18, and is opened and closed by an actuator 40. The first intake port 16 enters the combustion chamber 14 from a direction closer to the horizontal direction than the second intake port 18, and the first intake port 16 with the swirl control valve 38 closed.
The swirl (transverse swirl) generation in the combustion chamber 14 is promoted by the intake air from.

【００１９】各排気ポート２０は、排気マニホールド４
１を介して共通排気管４２に接続され、この共通排気管
４２の途中にＮＯｘ浄化触媒４４が設けられており、こ
のＮＯｘ浄化触媒４４の上流側にはＯ2センサ４６が設
けられている。上記ＮＯｘ浄化触媒４４には、この実施
例では三元触媒が用いられている。Each exhaust port 20 is connected to the exhaust manifold 4
1 is connected to the common exhaust pipe 42, a NOx purification catalyst 44 is provided in the middle of the common exhaust pipe 42, and an O 2 sensor 46 is provided upstream of the NOx purification catalyst 44. A three-way catalyst is used as the NOx purification catalyst 44 in this embodiment.

【００２０】上記共通排気管４２と、吸気系（図例では
サージタンク３２）とは、排ガス還流用のＥＧＲ管４８
を介して接続され、このＥＧＲ管４８の途中にＥＧＲ弁
５０が設けられている。このＥＧＲ弁５０は、ダイヤフ
ラム弁で構成され、その内部が圧力導入管５４を介して
三方切換弁５６の第１ポート、第２ポート、大気開放ポ
ートのうちの第２ポートに接続されるとともに、この三
方切換弁５６の第１ポートが圧力導入管５２を介して上
記サージタンク３２に接続されている。この三方切換弁
５６は、制御信号を受けて弁切換されるものであり、そ
の第１ポートと第２ポートとが連通された状態では、サ
ージタンク３２内の負圧により上記ＥＧＲ弁５０が開か
れ、大気ポートと第２ポートとが連通された場合には、
ＥＧＲ弁５０が閉じられるように構成されている。ま
た、このＥＧＲ弁５０が開いた時のＥＧＲ率（排気還流
率）が２０％以上となるように、ＥＧＲ系が構成されて
いる。The common exhaust pipe 42 and the intake system (surge tank 32 in the illustrated example) are the EGR pipe 48 for exhaust gas recirculation.
An EGR valve 50 is provided in the middle of this EGR pipe 48. The EGR valve 50 is composed of a diaphragm valve, and the inside of the EGR valve 50 is connected to the second port of the first port, the second port, and the atmosphere opening port of the three-way switching valve 56 via the pressure introducing pipe 54. The first port of the three-way switching valve 56 is connected to the surge tank 32 via the pressure introducing pipe 52. The three-way switching valve 56 is switched in response to a control signal. When the first port and the second port are in communication with each other, the EGR valve 50 is opened by the negative pressure in the surge tank 32. If the air port and the second port are connected,
The EGR valve 50 is configured to be closed. Further, the EGR system is configured so that the EGR rate (exhaust gas recirculation rate) when the EGR valve 50 is opened is 20% or more.

【００２１】さらに、このエンジンの特徴として、吸気
ポート１６，１８とは別の混合気供給ポート５７が、上
記点火プラグ２６近傍のボア中心部に対して略シリンダ
中心線方向（図では上下方向）に開口している。この混
合気供給ポート５７は、閉空間とされ、その内部にイン
ジェクタ６０から燃料が噴射されるようになっており、
燃焼室１４内に対しては混合気供給ポート５７がセンタ
ー弁５８の作動により開閉されるようになっている。Further, as a feature of this engine, the air-fuel mixture supply port 57 different from the intake ports 16 and 18 is approximately in the cylinder center line direction (vertical direction in the figure) with respect to the center of the bore near the ignition plug 26. It is open to. The air-fuel mixture supply port 57 is a closed space, and fuel is injected from the injector 60 into the space.
The air-fuel mixture supply port 57 is opened and closed in the combustion chamber 14 by the operation of the center valve 58.

【００２２】図３は、上記吸気弁２２及びセンター弁５
８のバルブタイミングをそれぞれ破線７１及び実線７２
で示したものである。図示のように、吸気弁２２の開弁
期間は、ピストン上死点手前からピストン下死点直後ま
でとされ、センター弁５８の開弁期間（すなわち混合気
供給ポート５７の開口期間）は、ピストン下死点の手前
（すなわち吸気行程後半）から次のピストン上死点手前
（すなわち圧縮行程後半）までとされている。FIG. 3 shows the intake valve 22 and the center valve 5 described above.
The valve timings of 8 are the broken line 71 and the solid line 72, respectively.
It is shown in. As shown in the drawing, the intake valve 22 is opened from before the piston top dead center to immediately after the piston bottom dead center, and the center valve 58 is opened (that is, the mixture supply port 57 is opened). It is from before the bottom dead center (that is, the latter half of the intake stroke) to before the next piston top dead center (that is, the latter half of the compression stroke).

【００２３】このエンジンでは、上記Ｏ2センサ４６の
他、エンジン回転数センサ６４、吸気圧センサ６６、ス
ロットルセンサ６８等の各センサ類が設けられ、これら
の検出信号がＥＣＵ７０に入力されるようになってい
る。このＥＣＵ７０は、上記検出信号から把握される運
転状態に応じて、次の制御を行うように構成されてい
る。 特定の運転領域（例えばアイドル運転領域を除く領
域）でアクチュエータ４０に制御信号を出力し、スワー
ルコントロール弁３８を閉弁させる。 上記領域で三方切換弁５６に制御信号を出力し、ＥＧ
Ｒ弁５０を開弁させる。 インジェクタ６０にパルス信号を出力し、燃料噴射時
期及び燃料噴射量を制御する。具体的には、センター弁
５８の開弁の少し手前の時点で燃料噴射を開始させ、Ｏ
2センサ４６の検出信号に基づき、空燃比を各運転領域
に対応する目標空燃比に維持するように燃料噴射量をフ
ィードバック制御する。ここで、目標空燃比は、エンジ
ン負荷が一定未満の速低負荷運転領域では１８、エンジ
ン負荷が一定以上の高負荷運転領域では略理論空燃比
（14.7）に設定されている。In addition to the O 2 sensor 46, this engine is provided with various sensors such as an engine speed sensor 64, an intake pressure sensor 66, a throttle sensor 68, etc., so that detection signals of these sensors are input to the ECU 70. Has become. The ECU 70 is configured to perform the following control according to the operating state grasped from the detection signal. A control signal is output to the actuator 40 in a specific operation region (for example, a region excluding the idle operation region) to close the swirl control valve 38. In the above range, the control signal is output to the three-way switching valve 56, and the EG
The R valve 50 is opened. A pulse signal is output to the injector 60 to control the fuel injection timing and the fuel injection amount. Specifically, fuel injection is started at a point slightly before the opening of the center valve 58, and O
2 Based on the detection signal of the sensor 46, the fuel injection amount is feedback-controlled so that the air-fuel ratio is maintained at the target air-fuel ratio corresponding to each operating region. Here, the target air-fuel ratio is set to 18 in the high-speed low-load operating region where the engine load is less than a constant value, and is set to approximately the theoretical air-fuel ratio (14.7) in the high-load operating region where the engine load is equal to or higher than the constant value.

【００２４】次に、このエンジンの作用を説明する。Next, the operation of this engine will be described.

【００２５】まず、上記特定の運転領域で、スワールコ
ントロール弁３８が閉弁され、第１吸気ポート１６から
のみ吸気がなされ、この吸気により燃焼室１４内にスワ
ールが生成される。一方、混合気供給ポート５７では、
前行程で圧入されたエアにインジェクタ６０から燃料が
噴射されて混合気が形成され、吸気行程後半でセンター
弁５８が開弁された当初は、吸気負圧により上記混合気
が混合気供給ポート５７から燃焼室１４内に引出され
る。その後、圧縮行程に入って燃焼室１４内圧力が高ま
ると、その中のエアが逆に混合気供給ポート５７内に押
し込まれ、センター弁５８が閉弁した時点で閉じ込めら
れる。この繰り返しにより、毎サイクルで燃焼室１４に
対する混合気供給がなされる。First, in the above-mentioned specific operation region, the swirl control valve 38 is closed, intake air is taken in only from the first intake port 16, and swirl is generated in the combustion chamber 14 by this intake air. On the other hand, at the air-fuel mixture supply port 57,
At the beginning of opening the center valve 58 in the latter half of the intake stroke, fuel is injected from the injector 60 into the air injected in the previous stroke, and the air-fuel mixture is supplied to the air-fuel mixture supply port 57 at the beginning when the center valve 58 is opened. Is drawn into the combustion chamber 14. After that, when the pressure in the combustion chamber 14 rises in the compression stroke, the air therein is conversely pushed into the mixture supply port 57 and is confined when the center valve 58 is closed. By repeating this, the air-fuel mixture is supplied to the combustion chamber 14 in each cycle.

【００２６】この供給混合気は、この燃焼室１４内に生
成されたスワール中心部に供給されて成層化され、ボア
中心部の点火プラグ２６の周囲を取り巻く。このため、
ＥＧＲ率を２０％以上と高く設定しても、良好な燃焼性
が確保され、エンジンの失火が防がれる。しかも、低負
荷運転領域では、上記のような混合気成層化及びＥＧＲ
が空燃比１８で同時実行されることにより、後の実験デ
ータでも示されるように、燃焼が活発化されて熱効率が
高くなり、ＥＧＲを行わない場合よりも燃費が大幅に向
上する。また、空燃比１８ではＮＯｘ浄化触媒４４であ
る三元触媒のＨＣ浄化性能が高く、ここでもエミッショ
ンは改善される。The supply air-fuel mixture is supplied to the center of the swirl formed in the combustion chamber 14 to be stratified and surrounds the spark plug 26 in the center of the bore. For this reason,
Even if the EGR rate is set as high as 20% or more, good combustibility is ensured and engine misfire is prevented. Moreover, in the low load operation region, the above-described mixture stratification and EGR are performed.
Is simultaneously executed with the air-fuel ratio of 18, the combustion is activated, the thermal efficiency is increased, and the fuel efficiency is significantly improved as compared with the case where the EGR is not performed, as shown in the experimental data described later. Further, at the air-fuel ratio 18, the HC purification performance of the three-way catalyst that is the NOx purification catalyst 44 is high, and the emission is improved here as well.

【００２７】これに対し、運転状態が高負荷運転領域に
移行すると、目標空燃比が略理論空燃比に切換えられる
ため、高トルク要求を満たすことができ、また、空燃比
を上記１６〜２０の範囲よりも下げる分、燃焼を緩慢に
してＮＯｘ発生をより抑えることが可能になる。しか
も、上記三元触媒ではＨＣ、ＣＯ、及びＮＯｘの全ての
浄化性能が高く、エミッションはさらに改善される。On the other hand, when the operating state shifts to the high load operating region, the target air-fuel ratio is switched to the substantially stoichiometric air-fuel ratio, so that the high torque requirement can be satisfied, and the air-fuel ratio of the above 16 to 20 is satisfied. The amount lower than the range makes it possible to slow the combustion and further suppress the generation of NOx. Moreover, the three-way catalyst has high purification performance for all of HC, CO, and NOx, and emission is further improved.

【００２８】＊実験データ 本発明者等は、ＥＧＲと、混合気供給ポート５７を用い
た混合気成層化とを同時実行した時のエンジン特性を調
べるべく、種々の実験を行った。その結果を図４〜図７
に示す。各図の示す内容は次の通りである。 図４：理論空燃比（14.7）でＥＧＲを行った場合、リー
ン空燃比（18.0）でＥＧＲを行った場合、及びＥＧＲを
せずに希薄燃焼を行った場合の筒内指圧及び熱発生率と
の関係。 図５：理論空燃比でＥＧＲを行った場合、空燃比18.0で
ＥＧＲを行った場合、及び空燃比20.0でＥＧＲを行った
場合のＥＧＲ率と燃料消費量との関係。 図６：理論空燃比でＥＧＲを行った場合、リーン空燃比
でＥＧＲを行った場合、及びＥＧＲをせずに希薄燃焼を
行った場合のマニホールドゲージ圧（吸気負圧）と熱効
率との関係。 図７：理論空燃比でＥＧＲを行った場合、リーン空燃比
でＥＧＲを行った場合、及び理論空燃比でＥＧＲを行わ
なかった場合の正味平均有効圧力（エンジン負荷に相
当）と燃料消費量との関係。* Experimental data The present inventors conducted various experiments to investigate engine characteristics when EGR and mixture stratification using the mixture supply port 57 were simultaneously performed. The results are shown in FIGS.
Shown in The contents shown in each figure are as follows. Fig. 4: In-cylinder finger pressure and heat release rate when EGR is performed at the theoretical air-fuel ratio (14.7), when EGR is performed at the lean air-fuel ratio (18.0), and when lean combustion is performed without EGR. connection of. FIG. 5: Relationship between EGR rate and fuel consumption when EGR is performed at the stoichiometric air-fuel ratio, when EGR is performed at the air-fuel ratio 18.0, and when EGR is performed at the air-fuel ratio 20.0. FIG. 6: Relationship between manifold gauge pressure (intake negative pressure) and thermal efficiency when EGR is performed at the stoichiometric air-fuel ratio, when EGR is performed at the lean air-fuel ratio, and when lean combustion is performed without EGR. Figure 7: Net average effective pressure (equivalent to engine load) and fuel consumption when EGR is performed at the stoichiometric air-fuel ratio, when EGR is performed at the lean air-fuel ratio, and when EGR is not performed at the stoichiometric air-fuel ratio connection of.

【００２９】図４に示すように、最大燃焼圧力は、理論
空燃比でＥＧＲを行った場合、及びＥＧＲ無しで希薄燃
焼を行った場合よりも、空燃比18.0でＥＧＲを行った場
合（本実施例での低負荷運転）の方が高く、熱発生率
は、理論空燃比でＥＧＲを行った場合よりも、ＥＧＲ無
しで希薄燃焼を行った場合及び空燃比18.0でＥＧＲを行
った場合（本実施例での低負荷運転）の方が高い。よっ
て、本実施例の低負荷運転領域での燃焼は、他の燃焼に
比べて熱発生が著しく、活発な燃焼であると言える。As shown in FIG. 4, the maximum combustion pressure is when the EGR is performed at an air-fuel ratio of 18.0 as compared with the case where the EGR is performed at the stoichiometric air-fuel ratio and when the lean combustion is performed without EGR (the present embodiment). (Low load operation in the example) is higher, and the heat release rate is higher when the lean combustion is performed without EGR and when EGR is performed at an air-fuel ratio of 18.0 than when EGR is performed at the stoichiometric air-fuel ratio (main Low load operation in the example) is higher. Therefore, it can be said that the combustion in the low load operation region of the present embodiment is more active in heat generation than the other combustions, and is active combustion.

【００３０】このため、図５に示されるように、本実施
例の低負荷運転領域での燃焼は、理論空燃比でＥＧＲを
行った場合よりも燃費がはるかに良くなり、図６に示す
ように、熱効率も大幅に高くなる。このように、ＥＧＲ
を行わない希薄燃焼よりも熱効率が良くなるのは、吸気
系へ還流される排ガスが新気よりも高温であるため、燃
料の気化・霧化が促進されることに起因すると考えられ
る。Therefore, as shown in FIG. 5, the combustion in the low load operation range of this embodiment has a much better fuel consumption than the case of performing EGR at the stoichiometric air-fuel ratio, and as shown in FIG. In addition, the thermal efficiency will be significantly higher. In this way, EGR
It is considered that the reason why the thermal efficiency is higher than that of the lean combustion without performing the above is that the vaporization and atomization of the fuel are promoted because the exhaust gas recirculated to the intake system is higher in temperature than the fresh air.

【００３１】しかも、図７の上段及び中段に示すよう
に、ＥＧＲ率が２０％以上の領域では、ＮＯｘ発生量を
十分に抑制でき、しかも、同図下段に示されるように、
ＥＧＲを行わずに理論空燃比で運転を行った場合よりも
燃費を改善することが可能となっている。これは、上記
の熱効率向上と、ポンピングロスの低減とに起因するも
のと考えられる。Moreover, as shown in the upper and middle rows of FIG. 7, in the region where the EGR rate is 20% or more, the NOx generation amount can be suppressed sufficiently, and as shown in the lower row of the figure,
It is possible to improve fuel efficiency as compared with the case of operating at the stoichiometric air-fuel ratio without performing EGR. This is considered to be due to the above-mentioned improvement in thermal efficiency and reduction in pumping loss.

【００３２】なお、図５及び図７の下段に示されるよう
に、空燃比を20.0にした場合、空燃比が18.0の場合より
も燃費は若干劣るが、理論空燃比の場合に比べれば燃費
は十分改善されている。従って、１８を中心とする１６
〜２０の範囲で空燃比を設定すれば、燃費の大幅節減が
期待できる。As shown in the lower part of FIGS. 5 and 7, when the air-fuel ratio is set to 20.0, the fuel consumption is slightly inferior to that when the air-fuel ratio is 18.0, but compared to the case of the theoretical air-fuel ratio, the fuel consumption is It has been improved sufficiently. Therefore, 16 around 18
If the air-fuel ratio is set in the range of ~ 20, a significant reduction in fuel consumption can be expected.

【００３３】なお、本発明は上記実施例に限定されるも
のでなく、例として次のような態様をとることも可能で
ある。The present invention is not limited to the above embodiment, and the following modes can be adopted as an example.

【００３４】(1) 上記実施例では、ＮＯｘ浄化触媒４４
として三元触媒を用いているが、これに代え、理論空燃
比だけでなくリーン空燃比でもＮＯｘ浄化性能をもつ触
媒を用いれば、低負荷運転領域でもＮＯｘ発生量を十分
に抑制できる利点がある。(1) In the above embodiment, the NOx purification catalyst 44
As an alternative, a three-way catalyst is used, but if a catalyst having NOx purification performance not only at the stoichiometric air-fuel ratio but also at the lean air-fuel ratio is used instead of this, there is an advantage that the NOx generation amount can be sufficiently suppressed even in the low load operation region. .

【００３５】(2) 本発明における混合気供給ポートは、
加圧エアと燃料とを混合して混合気を形成した上で燃焼
室内に供給するものであれば良く、上記のような閉空間
をもつものの他、エアポンプ等でエアを加圧して燃焼室
内に圧入するものでもよい。(2) The air-fuel mixture supply port according to the present invention is
It suffices if it mixes pressurized air and fuel to form an air-fuel mixture and then supplies it into the combustion chamber.In addition to the above-mentioned closed space, air is pressurized by an air pump etc. into the combustion chamber. It may be press-fitted.

【００３６】(3) 本発明において、混合気成層化とＥＧ
Ｒとを同時実行する運転領域は、自由に定めればよい。
また、空燃比を１６〜２０とする領域も、少なくとも低
負荷運転領域を含んでいればよく、高負荷運転領域での
トルク要求があまり高くないエンジンでは、全運転領域
を通じて空燃比を１６〜２０の範囲に設定するようにし
てもよい。(3) In the present invention, mixed gas stratification and EG
The operating range in which R and R are simultaneously executed may be freely set.
Further, the region where the air-fuel ratio is set to 16 to 20 only needs to include at least the low load operating region, and in an engine where the torque demand in the high load operating region is not so high, the air-fuel ratio is 16 to 20 throughout the entire operating region. You may make it set to the range of.

【００３７】(4) 本発明において、吸気ポート及び排気
ポートの数は特に問わず、自由に設定すればよい。(4) In the present invention, the number of intake ports and exhaust ports is not particularly limited, and may be set freely.

【００３８】[0038]

【発明の効果】以上のように本発明は、混合気供給ポー
トの使用とスワール生成とにより混合気を成層化すると
ともに、少なくとも低負荷運転領域において上記混合気
供給による筒内空燃比を１６〜２０に設定し、２０％以
上のＥＧＲ率でＥＧＲを行うようにしたものであるの
で、従来のようにＥＧＲをせずに希薄燃焼を行う場合
や、理論空燃比でＥＧＲを行う場合よりも燃費を大幅に
改善でき、しかも、エンジンの失火を避けながらの高い
ＥＧＲ率の設定によりＮＯｘ発生量を低減させることが
できる効果がある。As described above, according to the present invention, the air-fuel mixture is stratified by the use of the air-fuel mixture supply port and the swirl generation, and the in-cylinder air-fuel ratio by the air-fuel mixture supply of at least 16 is controlled in the low load operation region. Since it is set to 20 and EGR is performed at an EGR rate of 20% or more, fuel consumption is better than when performing lean combustion without EGR or when performing EGR at the stoichiometric air-fuel ratio as in the past. Is significantly improved, and further, the NOx generation amount can be reduced by setting a high EGR rate while avoiding engine misfire.

【００３９】ここで、請求項２記載の装置では、上記低
負荷運転領域よりも高負荷側の高負荷運転領域で上記筒
内空燃比を略理論空燃比に設定しているので、高トルク
要求を満たすことができ、また、１６〜２０の空燃比に
比べてＮＯｘ発生をより抑えることができる効果があ
る。According to the second aspect of the present invention, the in-cylinder air-fuel ratio is set to a substantially stoichiometric air-fuel ratio in the high-load operating region on the higher load side than the low-load operating region. And NOx generation can be further suppressed as compared with the air-fuel ratio of 16 to 20.

【００４０】請求項３記載の装置では、排気通路に設け
られた三元触媒により、エミッションの改善、特に、空
燃比１６〜２０の領域でＨＣを大幅に低減させることが
できる効果がある。In the apparatus according to the third aspect, the three-way catalyst provided in the exhaust passage has an effect of improving the emission, and in particular, capable of significantly reducing HC in the region of the air-fuel ratio of 16 to 20.

【００４１】さらに、上記三元触媒を請求項２の装置、
すなわち、高負荷運転領域で略理論空燃比とする装置に
設けたものによれば（請求項４）、高負荷側では上記Ｈ
Ｃに加え、ＣＯ、及びＮＯｘも大幅に低減させることが
でき、エミッションをさらに改善できる効果がある。Further, the three-way catalyst is used in the apparatus of claim 2,
That is, according to the device provided in the device that achieves a substantially stoichiometric air-fuel ratio in the high load operation region (claim 4), the above H on the high load side.
In addition to C, CO and NOx can be significantly reduced, and there is an effect that emission can be further improved.

【００４２】また、請求項５記載のように排気通路に理
論空燃比に加えてリーン空燃比でもＮＯｘ浄化性能をも
つ触媒を設ければ、上記のように空燃比を１６〜２０に
設定しても触媒でさらにＮＯｘを低減させることができ
る効果がある。Further, if a catalyst having NOx purification performance with a lean air-fuel ratio in addition to the stoichiometric air-fuel ratio is provided in the exhaust passage as described in claim 5, the air-fuel ratio is set to 16 to 20 as described above. Also has the effect that the catalyst can further reduce NOx.

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

【図１】本発明の一実施例におけるエンジンの全体構成
図である。FIG. 1 is an overall configuration diagram of an engine according to an embodiment of the present invention.

【図２】上記エンジンにおける各ポートの配置を示す模
式平面図である。FIG. 2 is a schematic plan view showing the arrangement of ports in the engine.

【図３】上記エンジンにおける吸気弁及びセンター弁の
バルブタイミングを示す図である。FIG. 3 is a diagram showing valve timings of an intake valve and a center valve in the engine.

【図４】上記エンジンにおいて、理論空燃比でＥＧＲを
行った場合、リーン空燃比でＥＧＲを行った場合、及び
ＥＧＲをせずに希薄燃焼を行った場合の筒内指圧及び熱
発生率を示すグラフである。FIG. 4 shows in-cylinder acupressure and heat release rate in the above engine when EGR is performed at a stoichiometric air-fuel ratio, when EGR is performed at a lean air-fuel ratio, and when lean combustion is performed without EGR. It is a graph.

【図５】上記エンジンにおいて、理論空燃比でＥＧＲを
行った場合、空燃比18.0でＥＧＲを行った場合、及び空
燃比20.0でＥＧＲを行った場合のＥＧＲ率と燃料消費量
との関係を示すグラフである。FIG. 5 shows the relationship between the EGR rate and the fuel consumption when EGR is performed at the stoichiometric air-fuel ratio, when EGR is performed at an air-fuel ratio of 18.0, and when EGR is performed at an air-fuel ratio of 20.0 in the above engine. It is a graph.

【図６】上記エンジンにおいて、理論空燃比でＥＧＲを
行った場合、リーン空燃比でＥＧＲを行った場合、及び
ＥＧＲをせずに希薄燃焼を行った場合のマニホールドゲ
ージ圧（吸気負圧）と熱効率との関係を示すグラフであ
る。FIG. 6 shows the manifold gauge pressure (intake negative pressure) when the EGR is performed at the stoichiometric air-fuel ratio, when the EGR is performed at the lean air-fuel ratio, and when lean combustion is performed without EGR in the above engine. It is a graph which shows the relationship with thermal efficiency.

【図７】上記エンジンにおいて、理論空燃比でＥＧＲを
行った場合、リーン空燃比でＥＧＲを行った場合、及び
理論空燃比でＥＧＲを行わなかった場合の正味平均有効
圧力と燃料消費量との関係を示すグラフである。FIG. 7 shows the net average effective pressure and fuel consumption when the EGR is performed at the stoichiometric air-fuel ratio, when the EGR is performed at the lean air-fuel ratio, and when the EGR is not performed at the stoichiometric air-fuel ratio in the above engine. It is a graph which shows a relationship.

【符号の説明】[Explanation of symbols]

１０ エンジン本体 １４ 燃焼室 １６，１８ 吸気ポート ２２ 吸気弁 ３８ スワールコントロール弁 ４２ 共通排気管 ４４ ＮＯｘ浄化触媒 ４６ Ｏ2センサ ４８ ＥＧＲ管 ５０ ＥＧＲ弁 ５７ 混合気供給ポート ５８ センター弁 ６０ インジェクタ ７０ ＥＣＵ10 Engine Body 14 Combustion Chamber 16, 18 Intake Port 22 Intake Valve 38 Swirl Control Valve 42 Common Exhaust Pipe 44 NOx Purification Catalyst 46 O 2 Sensor 48 EGR Pipe 50 EGR Valve 57 Mixture Supply Port 58 Center Valve 60 Injector 70 ECU

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｆ０２Ｄ 41/04 ３０５ Ｅ 43/00 ３０１ Ｅ Ｎ 45/00 ３０１ Ｆ Ｆ０２Ｍ 25/07 ５５０ Ｄ 61/14 ３２０ Ａ 69/04 Ｐ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Office reference number FI technical display location F02D 41/04 305 E 43/00 301 EN 45/00 301 F F02M 25/07 550 D 61 / 14 320 A 69/04 P

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 吸気ポートとは別に、加圧エアと燃料と
の混合により混合気を形成して燃焼室内に供給するため
の混合気供給ポートを備え、この混合気供給ポートの上
記燃焼室内に対する開口期間が吸気行程後半から圧縮行
程にかけての期間に設定されたエンジンの吸気装置にお
いて、上記吸気ポートをこの吸気ポートからの吸気によ
り燃焼室内にスワールが生成されるように配置し、上記
混合気供給ポートを点火プラグ近傍のボア中心部に対し
て略シリンダ中心線方向に開口させるとともに、上記吸
気ポートに排ガスを還流させる排ガス還流手段を備え、
少なくとも低負荷運転領域において上記混合気供給によ
る筒内空燃比を１６以上２０以下に設定し、上記排ガス
還流手段による排ガス還流率を２０％以上に設定したこ
とを特徴とするエンジンの吸気装置。1. An air-fuel mixture supply port for forming an air-fuel mixture by mixing pressurized air and fuel and supplying the air-fuel mixture into the combustion chamber is provided separately from the intake port, and the air-fuel mixture supply port with respect to the combustion chamber. In an intake system of an engine whose opening period is set to a period from the latter half of the intake stroke to the compression stroke, the intake port is arranged so that swirl is generated in the combustion chamber by the intake air from the intake port, and the mixture supply is performed. The port is opened substantially in the cylinder centerline direction with respect to the bore center near the spark plug, and exhaust gas recirculation means for recirculating exhaust gas to the intake port is provided,
At least in a low load operation region, an in-cylinder air-fuel ratio by the mixture supply is set to 16 or more and 20 or less, and an exhaust gas recirculation rate by the exhaust gas recirculation means is set to 20% or more. 【請求項２】 請求項１記載のエンジンの吸気装置にお
いて、上記低負荷運転領域よりも高負荷側の高負荷運転
領域では上記筒内空燃比を略理論空燃比に設定したこと
を特徴とするエンジンの吸気装置。2. The engine intake system according to claim 1, wherein the in-cylinder air-fuel ratio is set to a substantially stoichiometric air-fuel ratio in a high-load operating region on a higher load side than the low-load operating region. Engine intake device. 【請求項３】 請求項１記載のエンジンの吸気装置にお
いて、排気通路に三元触媒を設けたことを特徴とするエ
ンジンの吸気装置。3. The intake system for an engine according to claim 1, wherein a three-way catalyst is provided in the exhaust passage. 【請求項４】 請求項２記載のエンジンの吸気装置にお
いて、排気通路に三元触媒を設けたことを特徴とするエ
ンジンの吸気装置。4. The engine intake system according to claim 2, wherein a three-way catalyst is provided in the exhaust passage. 【請求項５】 請求項１または２記載のエンジンの吸気
装置において、排気通路に理論空燃比に加えてリーン空
燃比でもＮＯｘ浄化性能をもつ触媒を設けたことを特徴
とするエンジンの吸気装置。5. The engine intake system according to claim 1, wherein the exhaust passage is provided with a catalyst having NOx purification performance even in a lean air-fuel ratio in addition to the theoretical air-fuel ratio.
JP6219065A 1994-09-13 1994-09-13 Intake device for engine Pending JPH0882234A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP6219065A JPH0882234A (en) 1994-09-13 1994-09-13 Intake device for engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP6219065A JPH0882234A (en) 1994-09-13 1994-09-13 Intake device for engine

Publications (1)

Publication Number Publication Date
JPH0882234A true JPH0882234A (en) 1996-03-26

Family

ID=16729728

Family Applications (1)

Application Number Title Priority Date Filing Date
JP6219065A Pending JPH0882234A (en) 1994-09-13 1994-09-13 Intake device for engine

Country Status (1)

Country Link
JP (1) JPH0882234A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997020619A1 (en) * 1995-12-06 1997-06-12 Ict Co., Ltd. Method of controlling emission from gasoline engine
US9404406B2 (en) 1995-12-06 2016-08-02 Umicore Shokubai Japan Co., Ltd. Catalyst for use in a process for purifying exhaust gas from gasoline engines of a fuel-direct-injection type

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997020619A1 (en) * 1995-12-06 1997-06-12 Ict Co., Ltd. Method of controlling emission from gasoline engine
US9404406B2 (en) 1995-12-06 2016-08-02 Umicore Shokubai Japan Co., Ltd. Catalyst for use in a process for purifying exhaust gas from gasoline engines of a fuel-direct-injection type

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