JP2000337153A - Cylinder injection type spark ignition internal combustion engine - Google Patents

Cylinder injection type spark ignition internal combustion engine

Info

Publication number
JP2000337153A
JP2000337153A JP11143666A JP14366699A JP2000337153A JP 2000337153 A JP2000337153 A JP 2000337153A JP 11143666 A JP11143666 A JP 11143666A JP 14366699 A JP14366699 A JP 14366699A JP 2000337153 A JP2000337153 A JP 2000337153A
Authority
JP
Japan
Prior art keywords
cavity
side wall
fuel
cylinder
injection valve
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
JP11143666A
Other languages
Japanese (ja)
Inventor
Hiroshi Miyagawa
浩 宮川
Taketoshi Fujikawa
武敏 藤川
Toyoichi Umehana
豊一 梅花
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.)
Toyota Motor Corp
Toyota Central R&D Labs Inc
Original Assignee
Toyota Motor Corp
Toyota Central R&D Labs Inc
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 Toyota Motor Corp, Toyota Central R&D Labs Inc filed Critical Toyota Motor Corp
Priority to JP11143666A priority Critical patent/JP2000337153A/en
Publication of JP2000337153A publication Critical patent/JP2000337153A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • F02B75/00—Other engines
    • F02B75/12—Other methods of operation
    • F02B2075/125—Direct injection in the combustion chamber for spark ignition engines, i.e. not in pre-combustion chamber
    • 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

  • Combustion Methods Of Internal-Combustion Engines (AREA)

Abstract

PROBLEM TO BE SOLVED: To generate an optimum squish flow and reverse switch flow to realize a satisfactory stratified combustion by setting the clearance between the top surface of a piston and the upper wall of a cylinder in the last stage of compression stroke large in the vicinity of the fuel injection valve-side side wall of a cavity, in comparison to the vicinity of the opposite side wall thereof. SOLUTION: In the last stage of compression stroke, the top surface of a piston is approached to the upper wall of a cylinder to generate a squish flow between the both. The clearance between the piston top surface and the cylinder upper wall in the last stage of compression stroke is set large in the vicinity h1 of the fuel injection valve-side side wall 8b of a cavity 8, in comparison to the vicinity h2 of the opposite side wall 8c thereof. According to this, the first squish flow carried to the cavity 8 from the fuel injection valve-side side wall 8b of the cavity 8 is weakened, and the second squish flow carried to the cavity from the opposite side wall 8c of the cavity 8 is strengthened. Further, since the cavity 8 is off-centered from the piston top surface to provide a relatively wide area part in the vicinity of the opposite side wall 8c of the cavity 8, the second squish flow is further strengthened.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、筒内噴射式火花点
火内燃機関に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection spark ignition internal combustion engine.

【０００２】[0002]

【従来の技術】気筒内へ直接的に燃料を噴射する燃料噴
射弁を具備する筒内噴射式火花点火内燃機関は、圧縮行
程末期にピストン頂面に形成されたキャビティ内へ燃料
を噴射することにより、燃料を高温の空気とピストン熱
とを利用して気化させると共に点火プラグ近傍へ導き、
点火時点において、着火性の良好な可燃混合気を点火プ
ラグ近傍だけに形成し、気筒内全体としてリーンな混合
気を燃焼可能な成層燃焼を実現するものである。2. Description of the Related Art A direct injection type spark ignition internal combustion engine having a fuel injection valve for directly injecting fuel into a cylinder injects fuel into a cavity formed on a piston top surface at the end of a compression stroke. With this, the fuel is vaporized using the high-temperature air and the heat of the piston, and is guided to the vicinity of the spark plug,
At the time of ignition, a flammable mixture having good ignitability is formed only in the vicinity of the ignition plug, and stratified combustion capable of burning a lean mixture as a whole in the cylinder is realized.

【０００３】特開平９−１５８７３６号公報に開示され
ている筒内噴射式火花点火内燃機関のように、一般的に
は、燃料噴射弁は気筒上部周囲の吸気ポート側に配置さ
れ、点火プラグは気筒上部略中心に配置されている。ま
た、ピストン頂面に形成されたキャビティは、燃料噴射
弁から噴射された燃料が衝突する底壁と、燃料噴射弁側
側壁と、燃料噴射弁側側壁に対向する対向側壁とを有し
ており、この対向側壁によって、衝突後に底壁に沿って
進行する燃料を点火プラグ近傍に偏向するようになって
いる。[0003] As in the direct injection type spark ignition internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 9-158736, generally, a fuel injection valve is arranged on an intake port side around an upper portion of a cylinder, and a spark plug is provided. It is arranged substantially at the center of the upper part of the cylinder. The cavity formed on the piston top surface has a bottom wall against which fuel injected from the fuel injector collides, a fuel injector side wall, and an opposing side wall facing the fuel injector side wall. The opposed side wall deflects the fuel that travels along the bottom wall after the collision to the vicinity of the spark plug.

【０００４】この従来技術において、燃料噴射弁は、燃
料を比較的厚さの薄い平らな扇状に噴射するものであ
り、キャビティの底壁上を進行する燃料は、幅方向に拡
がって、周囲空気及び底壁の広範囲部分から熱吸収する
ために気化し易い。キャビティの対向側壁は、平面視に
おいて円弧形状を有しているために、幅方向に拡がって
良好に気化しつつある燃料各部分を点火プラグ近傍に集
合させて可燃混合気を形成できるとしている。In this prior art, the fuel injection valve injects fuel in a flat fan shape having a relatively small thickness, and the fuel traveling on the bottom wall of the cavity spreads in the width direction, and the surrounding air is diffused. And easy to vaporize due to heat absorption from a wide area of the bottom wall. Since the opposing side wall of the cavity has an arc shape in a plan view, it is stated that each part of the fuel, which spreads in the width direction and is well vaporized, can be gathered near the ignition plug to form a combustible mixture.

【０００５】[0005]

【発明が解決しようとする課題】しかしながら、前述の
従来技術では、圧縮行程末期で形成されるピストン頂面
と気筒上部壁との間の隙間について規定していない。こ
の隙間は、圧縮行程末期においてキャビティ内へ流入す
るスキッシュ流を発生させ、また、膨張行程初期におい
てキャビティ内から流出する逆スキッシュ流を発生させ
るものであり、発生するスキッシュ流又は逆スキッシュ
流によっては、点火プラグ近傍に可燃混合気が形成され
ても良好に燃焼させることができず、未燃燃料が増加し
たりする。However, the above-mentioned prior art does not specify the clearance between the piston top surface and the cylinder upper wall formed at the end of the compression stroke. This gap generates a squish flow flowing into the cavity at the end of the compression stroke, and generates a reverse squish flow flowing out of the cavity at the beginning of the expansion stroke. Even if a combustible air-fuel mixture is formed in the vicinity of the ignition plug, it cannot be satisfactorily burned, and unburned fuel increases.

【０００６】従って、本発明の目的は、圧縮行程後半に
ピストン頂面に形成されたキャビティ内に噴射された燃
料をキャビティの底壁上を進行させて対向側壁によって
点火プラグ近傍に導く筒内噴射式火花点火内燃機関にお
いて、圧縮行程末期で形成されるピストン頂面と気筒上
部壁との間の隙間を規定し、最適なスキッシュ流及び逆
スキッシュ流を発生させ、良好な成層燃焼を実現するこ
とである。Accordingly, it is an object of the present invention to provide an in-cylinder injection in which fuel injected into a cavity formed on the top surface of a piston in the latter half of a compression stroke is advanced on the bottom wall of the cavity and guided to the vicinity of a spark plug by an opposed side wall. In a spark ignition type internal combustion engine, a gap between a piston top surface formed at the end of a compression stroke and an upper wall of a cylinder is defined to generate optimal squish flow and reverse squish flow, thereby achieving good stratified combustion. It is.

【０００７】[0007]

【課題を解決するための手段】本発明による請求項１に
記載の筒内噴射式火花点火内燃機関は、気筒上部壁に配
置された点火プラグと、気筒内へ直接的に燃料を噴射す
る燃料噴射弁と、ピストン頂面に形成されたキャビティ
とを具備し、前記キャビティは、底壁と、燃料噴射弁側
側壁と、前記燃料噴射弁側側壁に対向する対向側壁とを
有し、前記燃料噴射弁から圧縮行程後半に前記キャビテ
ィ内に噴射された燃料を、前記キャビティの前記底壁上
を進行させた後に前記対向側壁によって偏向して前記点
火プラグ近傍に導く筒内噴射式火花点火内燃機関におい
て、圧縮行程末期における前記ピストン頂面と前記気筒
上部壁との間の隙間は、前記キャビティの前記対向側壁
近傍に比較して前記燃料噴射弁側側壁近傍において大き
くされていることを特徴とする。According to the first aspect of the present invention, there is provided a direct injection type spark ignition internal combustion engine having a spark plug disposed on an upper wall of a cylinder and a fuel for directly injecting fuel into the cylinder. An injection valve, and a cavity formed on a piston top surface, wherein the cavity has a bottom wall, a fuel injection valve side wall, and an opposing side wall facing the fuel injection valve side wall, An in-cylinder injection spark ignition internal combustion engine in which fuel injected into the cavity in the latter half of the compression stroke from an injection valve is advanced on the bottom wall of the cavity and then deflected by the opposed side wall and guided to the vicinity of the ignition plug. In the end of the compression stroke, the gap between the piston top surface and the cylinder upper wall is larger near the fuel injector side wall than near the opposite side wall of the cavity. And it features.

【０００８】また、本発明による請求項２に記載の筒内
噴射式火花点火内燃機関は、請求項１に記載の筒内噴射
式火花点火内燃機関において、前記燃料噴射弁は、比較
的厚さの薄い略扇形状に燃料を噴射することを特徴とす
る。According to a second aspect of the present invention, there is provided a cylinder injection type spark ignition internal combustion engine according to the first aspect, wherein the fuel injection valve has a relatively large thickness. It is characterized by injecting fuel in a generally fan-like thin shape.

【０００９】[0009]

【発明の実施の形態】図１は、本発明による筒内噴射式
火花点火内燃機関の実施形態を示す概略縦断面図であ
る。図２は、図１のピストンの平面図である。これらの
図において、１は吸気ポート、２は排気ポートである。
吸気ポート１は吸気弁３を介して、排気ポート２は排気
弁４を介して、それぞれ気筒内へ通じている。本実施形
態における筒内噴射式火花点火内燃機関は、特に、二つ
の吸気ポート１及び吸気弁３と、二つの排気ポート２及
び排気弁４とを有する吸排気二弁式であるが、これは、
本発明を限定するものではない。５はピストンであり、
その頂面には吸気弁３側に偏在して凹状のキャビティ８
が形成されている。６は気筒上部壁略中心に配置された
点火プラグであり、７は気筒上部周囲から気筒内へ直接
的に燃料を噴射するための燃料噴射弁である。燃料噴射
弁７は、燃料のベーパを防止するために、気筒内におい
て吸気流により比較的低温度となる吸気ポート１側に配
置されている。FIG. 1 is a schematic longitudinal sectional view showing an embodiment of a direct injection type spark ignition internal combustion engine according to the present invention. FIG. 2 is a plan view of the piston of FIG. In these figures, 1 is an intake port, and 2 is an exhaust port.
The intake port 1 communicates through the intake valve 3 and the exhaust port 2 communicates through the exhaust valve 4 into the cylinder. The in-cylinder injection spark ignition internal combustion engine in the present embodiment is an intake / exhaust two-valve engine having two intake ports 1 and intake valves 3 and two exhaust ports 2 and exhaust valves 4, in particular. ,
It does not limit the invention. 5 is a piston,
The top surface has a concave cavity 8 unevenly distributed on the intake valve 3 side.
Are formed. Reference numeral 6 denotes a spark plug disposed substantially at the center of the upper wall of the cylinder, and reference numeral 7 denotes a fuel injection valve for directly injecting fuel from the periphery of the upper part of the cylinder into the cylinder. The fuel injection valve 7 is disposed on the side of the intake port 1 where the temperature becomes relatively low due to the intake flow in the cylinder in order to prevent fuel vapor.

【００１０】また、燃料噴射弁７は、スリット状の噴孔
を有し、燃料を厚さの薄い扇状に噴射するものである。
必要燃料量が多い機関高負荷時には、吸気行程で燃料を
噴射して均質燃焼が実施されるが、それ以外の時には、
成層燃焼を実施するために、図２に示すように、圧縮行
程後半において燃料１００をピストン５の頂面に形成さ
れたキャビティ８内へ噴射する。キャビティ８は、燃料
噴射弁７から噴射された燃料が衝突する底壁８ａと、燃
料噴射弁側側壁８ｂと、燃料噴射弁側側壁８ｂに対向す
る対向側壁８ｃとを有している。燃料噴射弁７から扇状
に噴射された燃料は、液状であるが、キャビティ８の底
壁８ａに沿って進行して、キャビティ８の対向側壁８ｃ
によって点火プラグ６近傍へ導かれるまでに気化し、着
火性の良好な可燃混合気となる。こうして、点火プラグ
６近傍だけに可燃混合気を形成して、気筒内全体として
はリーンな混合気を燃焼可能とする燃費効率の高い成層
燃焼を実現することが意図されている。The fuel injection valve 7 has a slit-shaped injection hole, and injects fuel in a thin fan shape.
At high engine load, where the required fuel amount is large, fuel is injected during the intake stroke to perform homogeneous combustion, but at other times,
In order to perform stratified combustion, fuel 100 is injected into a cavity 8 formed on the top surface of the piston 5 in the latter half of the compression stroke, as shown in FIG. The cavity 8 has a bottom wall 8a against which fuel injected from the fuel injection valve 7 collides, a fuel injection valve side wall 8b, and an opposing side wall 8c facing the fuel injection valve side wall 8b. The fuel injected in a fan shape from the fuel injection valve 7 is in a liquid state, but proceeds along the bottom wall 8 a of the cavity 8 to face the opposite side wall 8 c of the cavity 8.
Thus, the mixture is vaporized before being guided to the vicinity of the ignition plug 6, and becomes a combustible mixture having good ignitability. Thus, it is intended to form a combustible mixture only in the vicinity of the ignition plug 6 and realize stratified combustion with high fuel efficiency that enables a lean mixture to be burned in the entire cylinder.

【００１１】厚さの薄い扇状の燃料噴霧は、キャビティ
８の底壁８ａに沿って進行する際に幅方向に拡がるため
に、キャビティ８内の高温度の空気と底壁８ａとの広範
囲部分から良好に熱を吸収して容易に気化することがで
きる。キャビティ８の対向側壁８ｃは、平面視において
円弧形状を有しているために、幅方向における燃料の中
央部分は、底壁８ａ上を進行する速度ベクトルが対向側
壁８ｃによって上方向の速度ベクトルへ変換され、点火
プラグ６近傍に向かうことを可能とする。また、幅方向
における燃料の両側部分は、対向側壁８ｃに対してそれ
ぞれ鋭角度に衝突することとなり、底壁８ａ上を進行す
る速度ベクトルが対向側壁８ｃによって上方向の速度ベ
クトルと中央方向の速度ベクトルとの合成速度ベクトル
に変換され、点火プラグ６近傍に向かうことを可能とす
る。こうして、点火プラグ６近傍に可燃混合気を形成す
ることが可能となる。The fan-shaped fuel spray having a small thickness spreads in the width direction as it proceeds along the bottom wall 8a of the cavity 8, so that the high-temperature air in the cavity 8 and the wide wall portion of the bottom wall 8a spread out. It absorbs heat well and can be easily vaporized. Since the opposing side wall 8c of the cavity 8 has an arc shape in a plan view, the central portion of the fuel in the width direction is such that the velocity vector traveling on the bottom wall 8a is changed to an upward velocity vector by the opposing side wall 8c. It is converted and can be directed to the vicinity of the ignition plug 6. Further, both sides of the fuel in the width direction collide with the opposing side wall 8c at an acute angle, and the velocity vector traveling on the bottom wall 8a is increased by the opposing side wall 8c and the velocity vector in the center direction. This is converted into a combined speed vector with the vector, and it is possible to move toward the vicinity of the ignition plug 6. Thus, a combustible mixture can be formed in the vicinity of the ignition plug 6.

【００１２】その後、圧縮行程末期となると、ピストン
頂面は気筒上部壁へ近接し、両者の隙間によってスキッ
シュ流が発生する。図２に示すように、発生したスキッ
シュ流は、キャビティ８の周囲から流入してキャビティ
８の中央部へ向かう。本実施形態では、圧縮行程末期に
おけるピストン頂面と気筒上部壁との間の隙間は、キャ
ビティ８の対向側壁８ｃ近傍（ｈ２）に比較して燃料噴
射弁側側壁８ｂ近傍（ｈ１）において大きくされてい
る。それにより、キャビティ８の燃料噴射弁側側壁８ｂ
からキャビティ８内へ流入する第一スキッシュＳ１は弱
く、キャビティ８の対向側壁８ｃからキャビティ８内へ
流入する第二スキッシュＳ２は強くなる。本実施形態に
おいては、キャビティ８がピストン頂面に偏在していて
キャビティ８の対向側壁８ｃ近傍に比較的広い面積部分
が存在しているために、第二スキッシュ流Ｓ２はさらに
強いものとなる。Thereafter, at the end of the compression stroke, the top surface of the piston approaches the upper wall of the cylinder, and a squish flow is generated by a gap between the two. As shown in FIG. 2, the generated squish flow flows in from around the cavity 8 and goes to the center of the cavity 8. In the present embodiment, the gap between the piston top surface and the cylinder upper wall at the end of the compression stroke is made larger near the fuel injection valve side wall 8b (h1) than near the opposing side wall 8c of the cavity 8 (h2). ing. Thereby, the fuel injector side wall 8b of the cavity 8
The first squish S1 flowing into the cavity 8 from the cavity 8 is weak, and the second squish S2 flowing from the opposing side wall 8c of the cavity 8 into the cavity 8 is strong. In the present embodiment, the second squish flow S2 is stronger because the cavity 8 is unevenly distributed on the piston top surface and a relatively large area exists near the opposing side wall 8c of the cavity 8.

【００１３】第二スキッシュ流Ｓ２は、点火プラグ６近
傍に形成された可燃混合気へ空気を供給して可燃混合気
と空気とを十分に混合させ、さらに可燃混合気を着火燃
焼させ易くする。また、可燃混合気１００’は、当初、
対向側壁８ｃに沿って点火プラグ６近傍に形成されてい
るが、図１に示すように、第二スキッシュ流Ｓ２によっ
て、対向側壁８ｃから離間させられる。この直後に点火
時期となって可燃混合気１００’は着火燃焼させられる
が、火炎がキャビティ８の壁面と接触しないために、燃
焼における熱損失は小さくなり、熱効率の高い成層燃焼
を実現することができる。第一スキッシュ流Ｓ１及び第
２スキッシュ流は、キャビティ８内に乱れを発生させ、
キャビティ８内での可燃混合気の燃焼速度を速めること
にも寄与する。The second squish flow S2 supplies air to the combustible mixture formed near the ignition plug 6 to sufficiently mix the combustible mixture with the air, and further facilitates the combustible mixture to ignite and burn. In addition, initially, the combustible mixture 100 ′
Although formed near the spark plug 6 along the opposing side wall 8c, as shown in FIG. 1, it is separated from the opposing side wall 8c by the second squish flow S2. Immediately thereafter, the ignition timing is reached, and the combustible mixture 100 'is ignited and burned. However, since the flame does not contact the wall surface of the cavity 8, the heat loss in combustion is reduced, and stratified combustion with high thermal efficiency can be realized. it can. The first squish flow S1 and the second squish flow generate turbulence in the cavity 8,
It also contributes to increasing the burning speed of the combustible mixture in the cavity 8.

【００１４】一方、キャビティ８の底壁８ａを進行する
際に気化した燃料の一部は、燃料の幅方向に分散してキ
ャビティ８の燃料噴射弁側側壁８ｂ近傍に希薄な混合気
を形成することがある。もし、このような希薄な混合気
が存在しても、第一スキッシュ流Ｓ１は弱いために、こ
の混合気をさらに希釈化させることはなく、この混合気
は第一スキッシュ流Ｓ１によってキャビティ８の中央部
へ移動させられて点火プラグ６近傍の可燃混合気と一体
化させられるために、未燃燃料として排出されることな
く良好に燃焼させることができる。On the other hand, a portion of the fuel vaporized when traveling along the bottom wall 8a of the cavity 8 is dispersed in the width direction of the fuel to form a lean mixture near the fuel injector side wall 8b of the cavity 8. Sometimes. Even if such a lean mixture exists, the first squish flow S1 is weak, so that the air-fuel mixture is not further diluted. Since it is moved to the center and integrated with the combustible air-fuel mixture in the vicinity of the ignition plug 6, it can be satisfactorily burned without being discharged as unburned fuel.

【００１５】こうして、点火プラグ６近傍の可燃混合気
が燃焼を開始すると、可燃混合気はキャビティ８内全体
へ急激に膨張して膨張行程初期となる。この時、キャビ
ティ８の周囲から空気が流出する逆スキッシュ流が発生
する。この逆スキッシュは、圧縮行程末期のスキッシュ
流と対応し、すなわち、キャビティ８の燃料噴射弁側側
壁８ｂからキャビティ８外へ流入する逆スキッシュは弱
く、キャビティ８の対向側壁８ｃからキャビティ８外へ
流入する逆スキッシュは強くなる。When the combustible air-fuel mixture near the ignition plug 6 starts to burn, the combustible air-fuel mixture rapidly expands into the entire cavity 8 and the initial stage of the expansion stroke. At this time, a reverse squish flow in which air flows out from around the cavity 8 is generated. This reverse squish corresponds to the squish flow at the end of the compression stroke, that is, the reverse squish flowing from the fuel injector side wall 8b of the cavity 8 to the outside of the cavity 8 is weak, and flows from the opposing side wall 8c of the cavity 8 to the outside of the cavity 8. The reverse squish becomes stronger.

【００１６】キャビティ８の対向側壁８ｃ近傍において
強い逆スキッシュ流が発生しても、この時には、対向側
壁８ｃ近傍の可燃混合気は燃焼しており、既燃ガスがキ
ャビティ８外へ流出するだけであるために、特に問題を
発生しない。しかしながら、前述したように、可燃混合
気は、燃焼開始と同時にキャビティ８内全体へ急激に膨
張して、未燃混合気が燃料噴射弁側側壁８ｂ近傍に位置
するために、キャビティ８の燃料噴射弁側側壁８ｂ近傍
において強い逆スキッシュ流が発生すると、この未燃混
合気は火炎伝播する以前にキャビティ８外へ流出し、燃
焼せずに未燃燃料として排出されることとなる。本実施
形態では、キャビティ８の燃料噴射弁側側壁８ｂ近傍に
おいて発生する逆スキッシュ流は弱いものとされるため
に、この問題が発生することは防止され、未燃燃料をも
たらさない良好な成層燃焼が実現可能である。Even if a strong reverse squish flow is generated in the vicinity of the opposing side wall 8c of the cavity 8, the combustible mixture near the opposing side wall 8c is burning at this time, and the burned gas only flows out of the cavity 8 There is no particular problem. However, as described above, the combustible air-fuel mixture rapidly expands into the entire cavity 8 simultaneously with the start of combustion, and the unburned air-fuel mixture is located near the fuel injector side wall 8b. If a strong reverse squish flow is generated in the vicinity of the valve side wall 8b, this unburned mixture flows out of the cavity 8 before the flame propagates, and is discharged as unburned fuel without burning. In the present embodiment, since the reverse squish flow generated in the vicinity of the fuel injector side wall 8b of the cavity 8 is weak, this problem is prevented from occurring, and good stratified combustion that does not bring unburned fuel is performed. Is feasible.

【００１７】本実施形態にように、厚さの薄い扇状の燃
料噴霧を使用することで、圧縮行程後半において比較的
多量の燃料を噴射しても、噴射された燃料を点火までに
ほぼ完全に気化させることができ、一般的な円錐状に燃
料を噴射する場合に比較して、吸気行程で燃料を噴射す
る均質燃焼運転領域を縮小すると共に、燃費効率の高い
成層燃焼運転領域を高負荷側に拡大することができる。By using a fan-shaped fuel spray having a small thickness as in this embodiment, even if a relatively large amount of fuel is injected in the latter half of the compression stroke, the injected fuel is almost completely discharged before ignition. Compared to the case of injecting fuel in a general cone shape, the homogeneous combustion operation area in which fuel is injected in the intake stroke can be reduced, and the stratified combustion operation area with high fuel efficiency can be increased on the high load side. Can be expanded to:

【００１８】しかしながら、これは、本発明を限定する
ものではなく、キャビティ内に噴射される燃料は、円錐
状であっても柱状であっても良い。また、ピストン頂面
のキャビティは、燃料が衝突する底壁と、燃料噴射弁側
側壁と、底壁上を進行する燃料を点火プラグ近傍に導く
対向側壁とを形状的に区別可能なものである。しかしな
がら、これは、本発明を限定するものではない。例え
ば、キャビティが略半球形状である場合のように、底壁
と対向側壁とが及び底壁と燃料噴射弁側側壁とが形状的
には区別できなくても、本発明は、燃料が衝突する部分
をキャビティを底壁として、また、この底壁上を進行す
る燃料を点火プラグ近傍に導く部分をキャビティの対向
側壁として、また、対向側壁に対向する部分を燃料噴射
弁側側壁として意図していることは明らかである。However, this does not limit the present invention, and the fuel injected into the cavity may be conical or columnar. Further, the cavity on the top surface of the piston can be distinguished in shape from the bottom wall against which the fuel collides, the side wall on the fuel injector side, and the opposing side wall for guiding the fuel traveling on the bottom wall to the vicinity of the ignition plug. . However, this is not a limitation of the present invention. For example, even when the bottom wall and the opposing side wall and the bottom wall and the fuel injection valve side wall cannot be distinguished in shape as in the case where the cavity has a substantially hemispherical shape, the present invention provides a fuel collision. The portion is intended to be a cavity as a bottom wall, the portion for guiding fuel traveling on the bottom wall to the vicinity of the ignition plug is intended as an opposing side wall of the cavity, and the portion opposing the opposing side wall is intended as a fuel injector side wall. It is clear that

【００１９】[0019]

【発明の効果】このように、本発明による筒内噴射式火
花点火内燃機関によれば、気筒上部壁に配置された点火
プラグと、気筒内へ直接的に燃料を噴射する燃料噴射弁
と、ピストン頂面に形成されたキャビティとを具備し、
キャビティは、底壁と、燃料噴射弁側側壁と、燃料噴射
弁側側壁に対向する対向側壁とを有し、燃料噴射弁から
圧縮行程後半にキャビティ内に噴射された燃料を、キャ
ビティの底壁上を進行させた後に対向側壁によって偏向
して点火プラグ近傍に導く筒内噴射式火花点火内燃機関
において、圧縮行程末期におけるピストン頂面と気筒上
部壁との間の隙間は、キャビティの対向側壁近傍に比較
して燃料噴射弁側側壁近傍において大きくされている。
それにより、圧縮行程後半において発生するスキッシュ
流は、キャビティの対向側壁近傍に比較して、キャビテ
ィの燃料噴射弁側側壁近傍において弱くなり、キャビテ
ィ内の燃料噴射弁側側壁近傍に位置する混合気の過剰な
希釈を防止する。さらに膨張行程初期において、キャビ
ティ内の燃料噴射弁側側壁近傍で発生する逆スキッシュ
流は、対向側壁近傍で発生する逆スキッシュ流に比較し
て弱いものとなり、点火プラグ近傍の可燃混合気が燃焼
開始と同時にキャビティ内全体に急激に膨張して、膨張
行程初期には燃料噴射弁側側壁近傍に未燃混合気が存在
するが、この未燃混合気が逆スキッシュ流によってキャ
ビティ外へ流出して燃焼せずに未燃燃料として排出され
ることは防止され、良好な成層燃焼を実現することがで
きる。As described above, according to the direct injection type spark ignition internal combustion engine of the present invention, the spark plug disposed on the upper wall of the cylinder, the fuel injection valve for directly injecting fuel into the cylinder, A cavity formed on the top surface of the piston,
The cavity has a bottom wall, a fuel injector side wall, and an opposing side wall facing the fuel injector side wall. The fuel injected from the fuel injector into the cavity in the second half of the compression stroke is supplied to the cavity bottom wall. In a cylinder injection type spark ignition internal combustion engine which is deflected by the opposed side wall after being advanced upward and guided to the vicinity of the spark plug, the gap between the piston top surface and the cylinder upper wall at the end of the compression stroke is near the opposed side wall of the cavity. In the vicinity of the side wall on the fuel injection valve side, the size is increased.
As a result, the squish flow generated in the latter half of the compression stroke becomes weaker near the fuel injector side wall in the cavity than in the vicinity of the opposing side wall of the cavity, and the air-fuel mixture located near the fuel injector side wall in the cavity is reduced. Prevent excessive dilution. Furthermore, at the beginning of the expansion stroke, the reverse squish flow generated near the fuel injector side wall in the cavity becomes weaker than the reverse squish flow generated near the opposing side wall, and the combustible mixture near the ignition plug starts burning. At the same time, the entire inside of the cavity expands rapidly, and an unburned air-fuel mixture exists near the side wall of the fuel injection valve at the beginning of the expansion stroke, but this unburned air-fuel mixture flows out of the cavity by the reverse squish flow and burns. It is possible to prevent the fuel from being discharged as unburned fuel without performing such a process, and to achieve good stratified combustion.

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

【図１】本発明による筒内噴射式火花点火内燃機関の実
施形態を示す概略縦断面図である。FIG. 1 is a schematic longitudinal sectional view showing an embodiment of a direct injection spark ignition internal combustion engine according to the present invention.

【図２】図１のピストンの平面図である。FIG. 2 is a plan view of the piston of FIG. 1;

【符号の説明】[Explanation of symbols]

１…吸気ポート ２…排気ポート ５…ピストン ６…点火プラグ ７…燃料噴射弁 ８…キャビティ ８ａ…底壁 ８ｂ…燃料噴射弁側側壁 ８ｃ…対向側壁 DESCRIPTION OF SYMBOLS 1 ... Intake port 2 ... Exhaust port 5 ... Piston 6 ... Spark plug 7 ... Fuel injection valve 8 ... Cavity 8a ... Bottom wall 8b ... Fuel injection valve side wall 8c ... Opposite side wall

フロントページの続き (72)発明者 藤川 武敏 愛知県愛知郡長久手町大字長湫字横道41番 地の１ 株式会社豊田中央研究所内 (72)発明者 梅花 豊一 愛知県豊田市トヨタ町１番地 トヨタ自動 車株式会社内 Ｆターム(参考） 3G023 AA02 AB03 AC05 AD02 AD03 AD07 AD08 AD09 AG01 AG02Continued on the front page (72) Inventor Taketoshi Fujikawa 41-cho, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside of Toyota Central Research Laboratory Co., Ltd. 3G023 AA02 AB03 AC05 AD02 AD03 AD07 AD08 AD09 AD01 AG01 AG02

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 気筒上部壁に配置された点火プラグと、
気筒内へ直接的に燃料を噴射する燃料噴射弁と、ピスト
ン頂面に形成されたキャビティとを具備し、前記キャビ
ティは、底壁と、燃料噴射弁側側壁と、前記燃料噴射弁
側側壁に対向する対向側壁とを有し、前記燃料噴射弁か
ら圧縮行程後半に前記キャビティ内に噴射された燃料
を、前記キャビティの前記底壁上を進行させた後に前記
対向側壁によって偏向して前記点火プラグ近傍に導く筒
内噴射式火花点火内燃機関において、圧縮行程末期にお
ける前記ピストン頂面と前記気筒上部壁との間の隙間
は、前記キャビティの前記対向側壁近傍に比較して前記
燃料噴射弁側側壁近傍において大きくされていることを
特徴とする筒内噴射式火花点火内燃機関。A spark plug disposed on an upper wall of the cylinder;
A fuel injection valve for directly injecting fuel into a cylinder, and a cavity formed on a piston top surface, wherein the cavity has a bottom wall, a fuel injection valve side wall, and a fuel injection valve side wall. A fuel injector injected into the cavity in the latter half of the compression stroke from the fuel injection valve, after being advanced on the bottom wall of the cavity, deflected by the opposed side wall, and In the direct injection type spark ignition internal combustion engine, the gap between the piston top surface and the cylinder upper wall at the end of the compression stroke is closer to the fuel injection valve side wall than to the vicinity of the opposed side wall of the cavity. An in-cylinder injection spark ignition internal combustion engine characterized by being enlarged in the vicinity. 【請求項２】 前記燃料噴射弁は、比較的厚さの薄い略
扇形状に燃料を噴射することを特徴とする請求項１に記
載の筒内噴射式火花点火内燃機関。2. The in-cylinder injection spark ignition internal combustion engine according to claim 1, wherein the fuel injection valve injects the fuel into a substantially fan shape having a relatively small thickness.
JP11143666A 1999-05-24 1999-05-24 Cylinder injection type spark ignition internal combustion engine Pending JP2000337153A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP11143666A JP2000337153A (en) 1999-05-24 1999-05-24 Cylinder injection type spark ignition internal combustion engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP11143666A JP2000337153A (en) 1999-05-24 1999-05-24 Cylinder injection type spark ignition internal combustion engine

Publications (1)

Publication Number Publication Date
JP2000337153A true JP2000337153A (en) 2000-12-05

Family

ID=15344121

Family Applications (1)

Application Number Title Priority Date Filing Date
JP11143666A Pending JP2000337153A (en) 1999-05-24 1999-05-24 Cylinder injection type spark ignition internal combustion engine

Country Status (1)

Country Link
JP (1) JP2000337153A (en)

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