JP2002147240A - Combustion chamber structure for diesel engine - Google Patents

Combustion chamber structure for diesel engine

Info

Publication number
JP2002147240A
JP2002147240A JP2000349287A JP2000349287A JP2002147240A JP 2002147240 A JP2002147240 A JP 2002147240A JP 2000349287 A JP2000349287 A JP 2000349287A JP 2000349287 A JP2000349287 A JP 2000349287A JP 2002147240 A JP2002147240 A JP 2002147240A
Authority
JP
Japan
Prior art keywords
combustion chamber
fuel
cavity
diesel engine
angle
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
JP2000349287A
Other languages
Japanese (ja)
Inventor
Hiroshi Ogawa
弘志 小川
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.)
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
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 Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Priority to JP2000349287A priority Critical patent/JP2002147240A/en
Publication of JP2002147240A publication Critical patent/JP2002147240A/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
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
    • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
    • F02B23/0696—W-piston bowl, i.e. the combustion space having a central projection pointing towards the cylinder head and the surrounding wall being inclined towards the cylinder wall
    • 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
    • F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
    • F02B2275/14—Direct injection into combustion chamber
    • 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
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
    • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
    • F02B23/0618—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston having in-cylinder means to influence the charge motion
    • F02B23/0621—Squish flow
    • 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
    • F02B23/00—Other engines characterised by special shape or construction of combustion chambers to improve operation
    • F02B23/02—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition
    • F02B23/06—Other engines characterised by special shape or construction of combustion chambers to improve operation with compression ignition the combustion space being arranged in working piston
    • F02B23/0645—Details related to the fuel injector or the fuel spray
    • F02B23/0648—Means or methods to improve the spray dispersion, evaporation or ignition
    • F02B23/0651—Means or methods to improve the spray dispersion, evaporation or ignition the fuel spray impinging on reflecting surfaces or being specially guided throughout the combustion space
    • 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
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/24—Cylinder heads
    • F02F2001/244—Arrangement of valve stems in cylinder heads
    • F02F2001/247—Arrangement of valve stems in cylinder heads the valve stems being orientated in parallel with the cylinder axis
    • 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

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the discharge quantity of the smoke and HC are increased and the exhaust performance is lowered when the fuel spray F directly interferes with a projection part 14 inside a cavity 4. SOLUTION: A fuel injection valve 12 for radially injecting the fuel at the predetermined spray angle Fθ into a combustion chamber 6 is provided. A nearly cylindrical cavity 4 is recessed at a nearly central part of a cap surface 3a of a piston 3. A nearly central part of a bottom surface 16 of the cavity 4 is formed with a nearly conical projection part 16 projected upward. An angle α of an inclined surface 13 of the projection part 14 formed with a reference horizontal surface Q crossing the cylinder center axis P is set larger than the angle α2 formed by a lower edge F2 of the fuel spray F injected from the fuel injection valve 12 near the top dead center of compression.

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、直接噴射式のディ
ーゼルエンジンの燃焼室構造に関する。The present invention relates to a combustion chamber structure of a direct injection type diesel engine.

【０００２】[0002]

【従来の技術】ディーゼルエンジンの燃焼室構造とし
て、エンジン排気中の煤濃度を低減させるとともに、エ
ンジン潤滑油に混入される煤の量を低下させることを目
的としたものが、特開平１０−１８４３６５号公報に記
載されている。2. Description of the Related Art Japanese Unexamined Patent Publication No. 10-184365 discloses a combustion chamber structure for a diesel engine which aims to reduce the soot concentration in engine exhaust and to reduce the amount of soot mixed into engine lubricating oil. No., published in Japanese Unexamined Patent Publication No.

【０００３】この従来例に係るディーゼルエンジンの燃
焼室構造では、ピストン冠面の上方に形成される燃焼室
の中央上部に、燃料を放射状に噴射する燃料噴射弁が配
設されるとともに、ピストン冠面の略中央部にキャビテ
ィが凹設されている。このキャビティ底部の略中央部に
は上方へ張り出した突起部が形成されており、キャビテ
ィの外表面は滑らかに湾曲する断面略ω状をなしてい
る。キャビティをこのような形状とすることにより、燃
焼室内での空気と燃料の混合を促進させて煤の排出量を
低減するとともに、エンジンの潤滑油に混入される煤の
量を低減させるようになっている。In the combustion chamber structure of the conventional diesel engine, a fuel injection valve for radially injecting fuel is disposed at the upper center of the combustion chamber formed above the piston crown, and the piston crown is formed. A cavity is formed substantially at the center of the surface. A projection projecting upward is formed substantially at the center of the bottom of the cavity, and the outer surface of the cavity has a substantially curved ω-shaped cross section. This shape of the cavity promotes the mixing of air and fuel in the combustion chamber, thereby reducing soot emission and reducing the amount of soot mixed into engine lubricating oil. ing.

【０００４】[0004]

【発明が解決しようとする課題】このようなキャビティ
を、冷却損失を低減する等のために浅皿化する場合、つ
まりキャビティの深さを浅くする場合、上記の従来例で
は、噴射された燃料がキャビティの周壁面に至る前に突
起部と干渉，付着して、スモークやＨＣ（ハイドロカー
ボン）の排出量が増加し、排気性能の低下を招くおそれ
がある。In the case where such a cavity is made shallow in order to reduce cooling loss or the like, that is, when the depth of the cavity is made shallow, in the above conventional example, the injected fuel May interfere with and adhere to the protrusions before reaching the peripheral wall surface of the cavity, thereby increasing the amount of smoke and HC (hydrocarbon) emitted, which may cause a reduction in exhaust performance.

【０００５】本発明は、このような課題に鑑みてなされ
たものであり、キャビティの浅皿化による冷却損失の低
減化を図りつつ、燃料噴霧が突起部等と干渉することに
よるスモークやＨＣの排出量の増加を抑制し、良好な燃
焼性能を実現し得る新規なディーゼルエンジンの燃焼室
構造を提供することを一つの目的としている。SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and aims to reduce the cooling loss by making the cavity shallower, and to reduce the smoke and HC generated by the fuel spray interfering with the projections. An object of the present invention is to provide a novel combustion chamber structure of a diesel engine capable of suppressing an increase in the amount of emission and achieving good combustion performance.

【０００６】[0006]

【課題を解決するための手段】本発明は、シリンダ内に
ピストンが摺動可能に配設されるとともに、このピスト
ンの冠面の上方に燃焼室が形成され、この燃焼室が、上
記ピストン冠面の略中央部に略円柱状に凹設されたキャ
ビティを含み、かつ、上記燃焼室の中央上部に、この燃
焼室内へ直接的かつ放射状に所定の噴霧角で燃料を噴射
する燃料噴射弁が配設されたディーゼルエンジンの燃焼
室構造に関する。According to the present invention, a piston is slidably disposed in a cylinder, and a combustion chamber is formed above a crown surface of the piston. A fuel injection valve for injecting fuel directly and radially at a predetermined spray angle into the combustion chamber is provided at a center upper portion of the combustion chamber, including a cavity formed in a substantially columnar shape at a substantially central portion of the surface. The present invention relates to a combustion chamber structure of a disposed diesel engine.

【０００７】上記のキャビティは、冷却損失の低減化等
を図るために、好ましくは十分に浅皿化される。具体的
には請求項５に係る発明のように、上記キャビティのシ
リンダ直径に対する口径比が０．６より大きく設定され
るとともに、上記キャビティの深さがシリンダ直径の１
／８より小さく設定される。The above-mentioned cavity is preferably made sufficiently shallow in order to reduce cooling loss and the like. Specifically, as in the invention according to claim 5, the ratio of the diameter of the cavity to the cylinder diameter is set to be larger than 0.6, and the depth of the cavity is 1 cylinder diameter.
It is set smaller than / 8.

【０００８】上記キャビティの底面の略中央部には、上
方へ略円錐状に張り出した突起部が形成されている。つ
まり、突起部は、キャビティ内に生成される旋回成分を
阻害することのないように、キャビティの底面の略中央
部に円錐状に形成されており、この突起部によって、旋
回成分を阻害することなくキャビティ内の空気利用率を
向上することができる。At the approximate center of the bottom surface of the cavity, a projection is formed which projects upward in a substantially conical shape. In other words, the projection is formed in a conical shape at a substantially central portion of the bottom surface of the cavity so as not to obstruct the swirling component generated in the cavity. And the air utilization rate in the cavity can be improved.

【０００９】そして、請求項１に係る発明では、シリン
ダ中心線に直交する基準水平面に対し、上記突起部の傾
斜面のなす角度が、圧縮上死点付近で燃料噴射弁から噴
射される燃料噴霧の下縁のなす角度よりも大きく設定さ
れていることを特徴としている。つまり、燃料噴霧の下
縁が突起部の傾斜面よりも緩い角度に設定されており、
燃料噴霧が噴射方向へ向かうに従って突起部から遠ざか
ることとなる。According to the first aspect of the present invention, the angle formed by the inclined surface of the projection with respect to a reference horizontal plane orthogonal to the cylinder center line is the fuel spray injected from the fuel injection valve near the compression top dead center. Is set to be larger than the angle formed by the lower edge. In other words, the lower edge of the fuel spray is set at a smaller angle than the inclined surface of the projection,
As the fuel spray moves in the injection direction, the fuel spray moves away from the protrusion.

【００１０】言い換えると、請求項２に係る発明のよう
に、圧縮上死点付近で燃料噴射弁から噴射される燃料噴
霧が上記突起部と直接的に干渉しないように、上記燃料
噴霧の主噴射方向及び噴霧角が設定されている。In other words, as in the invention according to the second aspect, the main injection of the fuel spray is performed so that the fuel spray injected from the fuel injection valve does not directly interfere with the protrusion near the compression top dead center. The direction and the spray angle are set.

【００１１】従って、キャビティを十分に浅皿化した場
合であっても、燃料噴霧がキャビティの底面に形成され
た突起部と直接的に干渉するおそれがなく、このような
干渉に起因するスモークやＨＣの増加が抑制され、排気
性能の低下を招く虞はない。Therefore, even when the cavity is made sufficiently shallow, there is no possibility that the fuel spray directly interferes with the projection formed on the bottom surface of the cavity. The increase in HC is suppressed, and there is no possibility that the exhaust performance is reduced.

【００１２】より好ましくは請求項３に係る発明のよう
に、圧縮上死点付近で燃料噴射弁から噴射される燃料噴
霧が、この燃料噴射弁が取り付けられるシリンダヘッド
の下部と干渉しないように、上記燃料噴霧の主噴射方向
及び噴霧角が設定されている。More preferably, the fuel spray injected from the fuel injector near the compression top dead center does not interfere with the lower part of the cylinder head to which the fuel injector is attached. The main injection direction and the spray angle of the fuel spray are set.

【００１３】具体的には、圧縮上死点付近での燃料噴霧
の上縁が、基準水平面と平行又はわずかに下方を指向す
るように設定されており、この上縁の延長線がキャビテ
ィの周壁面と交差するように設定されている。Specifically, the upper edge of the fuel spray near the compression top dead center is set so as to be parallel or slightly downward with respect to the reference horizontal plane, and an extension of this upper edge is defined as the circumference of the cavity. It is set to intersect the wall.

【００１４】また、請求項４に係る発明は、上記突起部
の半径が、上記燃料噴霧の***長さ、つまり液滴で噴射
された燃料が気化するまでに要する実質的な距離よりも
小さく設定されていることを特徴としている。より好ま
しくは、噴射圧等による燃料噴霧の***長さのばらつき
を考慮して突起部の半径が設定される。According to a fourth aspect of the present invention, the radius of the projection is set to be smaller than the split length of the fuel spray, that is, a substantial distance required for the fuel injected as droplets to vaporize. It is characterized by being. More preferably, the radius of the projection is set in consideration of the variation in the split length of the fuel spray due to the injection pressure or the like.

【００１５】請求項６に係る発明は、上記キャビティの
周壁面とピストン冠面とのなす角度が略９０°に設定さ
れていることを特徴としている。The invention according to claim 6 is characterized in that the angle between the peripheral wall surface of the cavity and the crown surface of the piston is set to approximately 90 °.

【００１６】請求項７に係る発明は、圧縮上死点付近で
燃料噴射弁から噴射された燃料噴霧が、上記キャビティ
の周壁面又は周壁面と底面とを滑らかに接続するコーナ
ー部を指向するように設定されていることを特徴として
いる。According to a seventh aspect of the present invention, the fuel spray injected from the fuel injection valve near the compression top dead center is directed to the peripheral wall surface of the cavity or a corner portion which smoothly connects the peripheral wall surface to the bottom surface. It is characterized by being set to.

【００１７】つまり、燃料噴霧がリンダヘッドの下部や
シリンダの内壁面の他、キャビティの底面や突起部と直
接的に干渉することのないように設定されている。In other words, the fuel spray is set so as not to directly interfere with the lower portion of the cylinder head, the inner wall surface of the cylinder, the bottom surface of the cavity and the projection.

【００１８】請求項８に係る発明は、上記燃料噴射弁の
先端部に、少なくとも６個以上の噴孔が周方向に間欠的
に設けられていることを特徴としている。The invention according to claim 8 is characterized in that at least six or more injection holes are provided intermittently in the circumferential direction at the tip of the fuel injection valve.

【００１９】[0019]

【発明の効果】請求項１又は２に係る発明によれば、燃
料噴射弁より噴射された燃料噴霧がキャビティの底面に
形成された突起部と干渉することがなく、両者の干渉に
起因するスモークやＨＣの増加等の排気性能の低下を確
実に防止することができる。According to the first or second aspect of the present invention, the fuel spray injected from the fuel injection valve does not interfere with the projection formed on the bottom surface of the cavity, and the smoke caused by the interference between the two. It is possible to reliably prevent a decrease in exhaust performance such as an increase in fuel consumption and HC.

【００２０】請求項３に係る発明によれば、所定の噴霧
角を有する燃料噴霧がシリンダヘッド下部に干渉するこ
とがないので、この干渉に起因するスモークやＨＣの増
加等の排気性能の低下を確実に回避することができる。According to the third aspect of the present invention, since the fuel spray having a predetermined spray angle does not interfere with the lower part of the cylinder head, a decrease in exhaust performance such as an increase in smoke and HC caused by the interference is prevented. It can be avoided reliably.

【００２１】請求項４に係る発明によれば、キャビティ
の底面に形成された突起部の半径を、燃料蒸発が生じ難
い燃料噴霧の***長さよりも小さくしたため、このよう
な蒸発燃料が突起部に付着する可能性が低く、スモーク
やＨＣ等の排出量を更に抑制することができる。According to the fourth aspect of the present invention, since the radius of the projection formed on the bottom surface of the cavity is made smaller than the split length of the fuel spray in which fuel evaporation is unlikely to occur, such evaporated fuel is formed on the projection. The possibility of adhesion is low, and the amount of emission of smoke, HC, and the like can be further suppressed.

【００２２】請求項５に係る発明によれば、キャビティ
が十分に浅皿化されるため、キャビティ内の流速の縦方
向速度の低下に伴い、冷却損失を十分に低下させること
ができ、ひいては燃費性能の向上を図ることができる。According to the fifth aspect of the present invention, since the cavity is made sufficiently shallow, cooling loss can be sufficiently reduced with a decrease in the longitudinal velocity of the flow velocity in the cavity, and fuel consumption can be further reduced. Performance can be improved.

【００２３】請求項６に係る発明によれば、キャビティ
の周壁面がピストン冠面に対して直角に近い角度となる
ため、キャビティ内の旋回成分を効果的に増加及び維持
することができ、燃焼性能の更なる向上を図ることがで
きる。According to the sixth aspect of the present invention, since the peripheral wall surface of the cavity has an angle close to a right angle with respect to the piston crown surface, the swirling component in the cavity can be effectively increased and maintained, and the combustion can be performed. The performance can be further improved.

【００２４】請求項７に係る発明によれば、燃料噴霧が
シリンダヘッドの下面やシリンダの内壁面の他、キャビ
ティの底面や突起部と直接的に干渉することがなく、こ
のような干渉によるスモークやＨＣの増加が回避され
る。According to the seventh aspect of the invention, the fuel spray does not directly interfere with the bottom surface of the cylinder head, the inner wall surface of the cylinder, the bottom surface of the cavity or the projection, and the smoke due to such interference does not occur. And an increase in HC is avoided.

【００２５】特に、請求項６及び請求項７の双方に係る
発明によれば、燃料噴霧がキャビティの周壁面へ直角に
近い衝突角度で衝突することとなる。この結果、燃料噴
霧の衝突後の分散が良好に行われ、燃焼性能が更に向上
する。In particular, according to the present invention, the fuel spray collides with the peripheral wall surface of the cavity at a collision angle close to a right angle. As a result, the dispersion of the fuel spray after the collision is favorably performed, and the combustion performance is further improved.

【００２６】請求項８に係る発明のように、噴孔を６個
以上設けることにより、噴孔が５個以下の場合に比し
て、燃料噴霧が周方向により均一に拡散される。このた
め、例えば請求項５に係る発明のようにキャビティを浅
皿化した場合、キャビティ内の旋回成分が相対的に弱く
なり、燃料噴霧が周方向に拡散され難くなる傾向にある
が、このような場合であっても、燃料噴霧を周方向に十
分に拡散させることができ、良好な燃焼性能を維持でき
る。By providing six or more injection holes as in the invention according to claim 8, the fuel spray is more uniformly diffused in the circumferential direction than in a case where the number of injection holes is five or less. For this reason, for example, when the cavity is made shallow, as in the invention according to claim 5, the swirl component in the cavity becomes relatively weak, and the fuel spray tends to be hardly diffused in the circumferential direction. Even in such a case, the fuel spray can be sufficiently diffused in the circumferential direction, and good combustion performance can be maintained.

【００２７】[0027]

【発明の実施の形態】以下、本発明の好ましい実施の形
態について図面を参照して説明する。図１は、本発明の
一実施例に係るディーゼルエンジンの燃焼室構造を示し
ている。エンジン本体の一部をなすシリンダブロック１
には、各気筒毎に円筒状のシリンダ２が形成されてお
り、各シリンダ２にはピストン３が摺動可能に配設され
ている。略円形をなすピストン３の上面すなわち冠面３
ａの上方には、燃焼室６が形成されている。つまり、燃
焼室６は、シリンダブロック１の上部に固定されるシリ
ンダヘッド５の下面と、シリンダ２の周壁面と、ピスト
ン３の冠面３ａとにより画成されている。そして、ピス
トン冠面３ａの略中央部には、略円柱状のキャビティ４
が凹設されており、このキャビティ４も燃焼室６の一部
を構成している。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a combustion chamber structure of a diesel engine according to one embodiment of the present invention. Cylinder block 1 that forms part of the engine body
, A cylindrical cylinder 2 is formed for each cylinder, and a piston 3 is slidably disposed in each cylinder 2. The upper surface or crown surface 3 of the piston 3 having a substantially circular shape
Above a, a combustion chamber 6 is formed. That is, the combustion chamber 6 is defined by the lower surface of the cylinder head 5 fixed to the upper part of the cylinder block 1, the peripheral wall surface of the cylinder 2, and the crown surface 3a of the piston 3. A substantially cylindrical cavity 4 is provided substantially at the center of the piston crown 3a.
The cavity 4 also forms a part of the combustion chamber 6.

【００２８】シリンダヘッド５には、エンジン外部から
燃焼室６へ吸気を供給する吸気通路７と、燃焼室６から
エンジン外部へ排気を排出する排気通路８と、が形成さ
れているとともに、吸気通路７を開閉する吸気弁９及び
排気通路８を開閉する排気弁１０が配設されている。ま
た、シリンダヘッド５には、燃焼室６の内部へ直接的に
燃料を噴射する燃料噴射弁１２が固設されている。この
燃料噴射弁１２は、シリンダ中心線Ｐに沿う起立姿勢で
燃焼室６の略中央上部に配設されており、燃焼室６に臨
んだ先端部には、少なくとも６個以上の噴孔１１が周方
向に間欠的に配設されている。これらの各噴孔１１から
燃料噴霧Ｆが所定の噴霧角Ｆθで放射状に噴射される。
この燃料噴射弁１２には、図示しない燃料噴射ポンプが
接続している。この燃料噴射ポンプの圧力の他、燃料噴
射弁１２による各気筒の燃料噴射量や燃料噴射時期等
は、図外のコントロールユニットからの制御信号によっ
て電気的に制御される。The cylinder head 5 is formed with an intake passage 7 for supplying intake air from outside the engine to the combustion chamber 6 and an exhaust passage 8 for discharging exhaust gas from the combustion chamber 6 to the outside of the engine. An intake valve 9 that opens and closes an exhaust passage 7 and an exhaust valve 10 that opens and closes an exhaust passage 8 are provided. Further, a fuel injection valve 12 for directly injecting fuel into the combustion chamber 6 is fixed to the cylinder head 5. The fuel injection valve 12 is disposed substantially above the center of the combustion chamber 6 in an upright posture along the cylinder center line P. At a tip portion facing the combustion chamber 6, at least six or more injection holes 11 are provided. They are arranged intermittently in the circumferential direction. Fuel spray F is radially injected from each of these injection holes 11 at a predetermined spray angle Fθ.
A fuel injection pump (not shown) is connected to the fuel injection valve 12. In addition to the pressure of the fuel injection pump, the fuel injection amount and fuel injection timing of each cylinder by the fuel injection valve 12 are electrically controlled by a control signal from a control unit (not shown).

【００２９】図２は、圧縮上死点付近における燃焼室６
の詳細な構造を示す図１の要部拡大図である。ピストン
冠面３ａに凹設されたキャビティ４は、直径Ｄ１で深さ
Ｈ１の略円柱形状をなしている。このキャビティ４の底
面１６には、その略中央部に、上方へ向けて略円錐形状
に張り出した突起部１４が一体的に形成されており、こ
の突起部１４の外表面は、断面山形の傾斜面１３をなし
ている。つまり、ピストン３，キャビティ４，突起部１
４及び燃料噴射弁１２が全てシリンダ中心線Ｐを中心と
して配置されている。FIG. 2 shows the combustion chamber 6 near the compression top dead center.
FIG. 2 is an enlarged view of a main part of FIG. 1 showing a detailed structure of FIG. The cavity 4 recessed in the piston crown 3a has a substantially cylindrical shape with a diameter D1 and a depth H1. The bottom surface 16 of the cavity 4 is formed integrally with a projection 14 projecting upward in a substantially conical shape at a substantially central portion thereof. The outer surface of the projection 14 has a slope having a mountain-shaped cross section. The surface 13 is formed. That is, piston 3, cavity 4, projection 1
4 and the fuel injection valve 12 are all arranged around the cylinder center line P.

【００３０】また、キャビティ４（燃焼室６）の内部に
適度な旋回成分が与えられるように、吸気通路７の向き
等が設定されている。そして、この旋回成分が比較的弱
いキャビティ４の中央部に、上記の突起部１４が設けら
れている。つまり、突起部１４は、旋回成分を弱めるこ
となくキャビティ４内の空気利用率を増加させて燃焼性
能の向上を図るためにキャビティ４の中央部に円錐状に
配設されている。The direction of the intake passage 7 is set so that an appropriate swirl component is given to the inside of the cavity 4 (combustion chamber 6). The projection 14 is provided at the center of the cavity 4 where the swirling component is relatively weak. That is, the protrusion 14 is conically arranged at the center of the cavity 4 in order to increase the air utilization rate in the cavity 4 without weakening the swirl component and improve the combustion performance.

【００３１】各噴孔１１から噴射される燃料噴霧Ｆは、
所定の主噴射方向Ｆ１を中心とした所定の噴霧角Ｆθの
範囲で放射状に噴射される。この主噴射方向Ｆ１の開き
角γは、例えば約１６０°に設定され、上記の噴霧角Ｆ
θは、例えば約２０゜に設定される。The fuel spray F injected from each injection hole 11 is:
Radial injection is performed in a range of a predetermined spray angle Fθ centered on a predetermined main injection direction F1. The opening angle γ of the main injection direction F1 is set to, for example, about 160 °, and the spray angle F
θ is set to, for example, about 20 °.

【００３２】このような構成により、エンジンの吸気行
程ではピストン３の下降に伴って吸気弁９が開弁され、
吸気通路７を通して外気が燃焼室６へ導入され、この燃
焼室６内にシリンダ中心線Ｐ回りの旋回成分が与えられ
る。そして、ピストン３が下死点まで下降した後、吸気
弁９が閉弁され、続くエンジンの圧縮行程では、ピスト
ン３の上昇とともに、燃焼室６内の吸入空気が圧縮され
て、旋回流が増速される。そして、圧縮上死点前後にお
いて、圧縮により十分高温となった燃焼室６のキャビテ
ィ４内へ、燃料噴射ポンプにより加圧された燃料を、燃
料噴射弁１２の先端部の噴孔１１より噴射する。これに
より、燃料噴霧が適宜に自己着火して燃焼が進行する。
そして、ピストン３が下降する膨張行程の後、エンジン
の排気行程では、ピストン３が再び上昇し、同時に排気
弁１０が開弁して、燃焼室６内の既燃ガスが排気通路８
を通じてエンジン外部に排出される。With this configuration, during the intake stroke of the engine, the intake valve 9 is opened as the piston 3 descends,
Outside air is introduced into the combustion chamber 6 through the intake passage 7, and a swirling component around the cylinder center line P is given into the combustion chamber 6. Then, after the piston 3 descends to the bottom dead center, the intake valve 9 is closed, and in the subsequent compression stroke of the engine, as the piston 3 rises, the intake air in the combustion chamber 6 is compressed and the swirling flow increases. Speeded up. Then, before and after the compression top dead center, the fuel pressurized by the fuel injection pump is injected into the cavity 4 of the combustion chamber 6 which has become sufficiently hot by the compression from the injection hole 11 at the tip of the fuel injection valve 12. . Thereby, the fuel spray appropriately ignites itself and combustion proceeds.
Then, after the expansion stroke in which the piston 3 is lowered, in the exhaust stroke of the engine, the piston 3 is raised again, and at the same time, the exhaust valve 10 is opened, and the burned gas in the combustion chamber 6 is discharged into the exhaust passage 8.
Through the engine.

【００３３】次に、本実施例の特徴的な構成及び作用効
果について列記する。先ず第１に、圧縮上死点付近で噴
射される燃料噴霧Ｆが突起部１４の傾斜面１３と直接的
に干渉することのないように、主噴射方向Ｆ１の向きや
噴霧角Ｆθ等が設定されている。Next, the characteristic structure, operation and effect of this embodiment will be listed. First, the direction of the main injection direction F1 and the spray angle Fθ are set so that the fuel spray F injected near the compression top dead center does not directly interfere with the inclined surface 13 of the projection 14. Have been.

【００３４】より具体的には、シリンダ中心線Ｐに直交
する基準水平面Ｑ、あるいは基準水平面Ｑと平行なキャ
ビティ４の底面１６に対し、突起部１４の傾斜面１３の
なす角度αを、所定の噴射角θ１で噴射される燃料噴霧
Ｆの下縁Ｆ２のなす角度α１よりも大きく設定してい
る。More specifically, the angle α formed by the inclined surface 13 of the projection 14 with respect to the reference horizontal plane Q orthogonal to the cylinder center line P or the bottom surface 16 of the cavity 4 parallel to the reference horizontal plane Q is set to a predetermined value. The angle is set to be larger than the angle α1 formed by the lower edge F2 of the fuel spray F injected at the injection angle θ1.

【００３５】この角度α１は、基準水平面Ｑに対して主
噴射方向Ｆ１がなす角度（１８０−γ）／２に、この主
噴射方向Ｆ１と下縁Ｆ２とのなす角度Ｆθ／２を加算し
た値となる。つまり、本実施例では、次式が成立するよ
うに設定されている。The angle α1 is a value obtained by adding an angle (180-γ) / 2 formed by the main injection direction F1 to the reference horizontal plane Q and an angle Fθ / 2 formed by the main injection direction F1 and the lower edge F2. Becomes That is, in this embodiment, the following equation is set.

【００３６】[0036]

【数１】α＞（１８０−γ＋Ｆθ）／２ これにより、燃料噴霧Ｆが突起部１４から遠ざかる形と
なり、この燃料噴霧Ｆの突起部１４への直接的な干渉が
確実に回避され、このような干渉に起因するＨＣやスモ
ークの増加等による排気性能の悪化を確実に抑制するこ
とができる。.Alpha.> (180-.gamma. + F.theta.) / 2 As a result, the fuel spray F is moved away from the projection 14, and direct interference of the fuel spray F with the projection 14 is reliably avoided. Thus, it is possible to reliably suppress the deterioration of the exhaust performance due to an increase in HC and smoke caused by excessive interference.

【００３７】第２に、キャビティ４を十分に浅皿化して
いる。具体的には、シリンダ２の直径Ｄ２に対するキャ
ビティ４の直径Ｄ１の比すなわちキャビティ４の口径比
Ｄ１／Ｄ２を、０．６よりも大きく設定しているととも
に、キャビティ４の軸方向深さＨ１を、シリンダ２の直
径Ｄ２の１／８よりも小さく設定している。Second, the cavity 4 is made sufficiently shallow. Specifically, the ratio of the diameter D1 of the cavity 4 to the diameter D2 of the cylinder 2, that is, the diameter ratio D1 / D2 of the cavity 4 is set to be larger than 0.6, and the depth H1 of the cavity 4 in the axial direction is set. , Smaller than 小 さ く of the diameter D2 of the cylinder 2.

【００３８】図３のグラフは、キャビティ４の深さＨ１
を十分に浅くした本実施例と、キャビティ４’の深さＨ
１’を相対的に深くした比較例について、圧縮上死点に
おけるキャビティ内のシリンダ軸方向の流速速度成分の
みを取り出して平均した値、すなわち縦方向平均速度を
示している。この値は、例えば三次元数値解析により算
出される。同図から明らかなように、本実施例のように
キャビティ４を十分に浅皿化することにより、比較例に
比して縦方向平均速度が大幅に抑制されることがわか
る。The graph of FIG. 3 shows the depth H1 of the cavity 4.
In this embodiment, the depth H of the cavity 4 ′ is sufficiently reduced.
In the comparative example in which 1 ′ is relatively deep, a value obtained by taking out and averaging only the flow velocity component in the cylinder axis direction in the cavity at the compression top dead center, that is, the average velocity in the vertical direction is shown. This value is calculated by, for example, three-dimensional numerical analysis. As can be seen from the figure, by making the cavity 4 sufficiently shallow as in the present embodiment, the average longitudinal speed is significantly suppressed as compared with the comparative example.

【００３９】図４は、エンジン試験により得られる上記
の縦方向平均速度と冷却損失割合との関係を示してい
る。同図に示すように、縦方向平均速度の低下に伴い、
冷却損失が低減する傾向にある。従って、本実施例のよ
うにキャビティ４を十分に浅皿化することにより、冷却
損失が大幅に低減し、エンジンの熱効率が高くなり、燃
費性能を大幅に向上させることが可能となる。例えば上
死点時の縦方向平均速度を５０％低下させると、冷却損
失を約１０％低減させることができる。FIG. 4 shows the relationship between the above average speed in the vertical direction and the cooling loss ratio obtained by the engine test. As shown in the figure, as the average longitudinal speed decreases,
Cooling loss tends to decrease. Therefore, by making the cavity 4 sufficiently shallow as in this embodiment, the cooling loss is greatly reduced, the thermal efficiency of the engine is increased, and the fuel efficiency can be greatly improved. For example, if the average longitudinal speed at the top dead center is reduced by 50%, the cooling loss can be reduced by about 10%.

【００４０】第３に、突起部１４の半径Ｌ１を、燃料噴
霧Ｆの***長さ（液滴で噴射された燃料が気化するまで
に要する距離）Ｌｂより小さくしている。これにより、
気化された蒸発燃料が突起部１４の傾斜面１３に付着す
る可能性が低くなり、これに起因する排気性能の低下を
より確実に防止できる。Third, the radius L1 of the projection 14 is made smaller than the split length Lb of the fuel spray F (the distance required for the fuel injected as droplets to evaporate) Lb. This allows
The possibility that the vaporized fuel vapor adheres to the inclined surface 13 of the projection 14 is reduced, and the reduction of the exhaust performance caused by this is more reliably prevented.

【００４１】なお、上記の***長さＬｂは、以下の式で
定義される。The split length Lb is defined by the following equation.

【００４２】[0042]

【数２】Ｌｂ＝α＊ＳＱＲ（ρ１／ρａ）＊Ｄ…（１） 但し、ρ１：燃料密度、ρａ：雰囲気密度、Ｄ：噴孔
径、α：補正係数 この式（１）によって求められる***長さＬｂは、噴射
圧等の条件により例えば１０〜２０ｍｍ程度の範囲でば
らつくおそれがある。従って、実際には、このようなば
らつきを考慮した***長さよりも突起部１４の半径Ｌ１
を小さく設定している。Lb = α * SQR (ρ1 / ρa) * D (1) where ρ1: fuel density, ρa: atmosphere density, D: injection hole diameter, α: correction coefficient Split obtained by this equation (1) The length Lb may vary within a range of, for example, about 10 to 20 mm depending on conditions such as the injection pressure. Therefore, actually, the radius L1 of the protrusion 14 is larger than the division length in consideration of such variations.
Is set small.

【００４３】第４に、圧縮上死点付近で噴射される燃料
噴霧Ｆが、シリンダヘッド５の下面やシリンダ２の周壁
面と直接的に干渉することのないように、主噴射方向Ｆ
１の向きや噴霧角Ｆθ等が設定されている。より具体的
には、燃料噴霧Ｆの上縁Ｆ３が、水平又はやや下向きに
傾斜するように設定されており、この上縁Ｆ３の延長線
が、圧縮上死点付近におけるキャビティ４の周壁面１５
と交差するように設定されている。つまり、圧縮上死点
付近における燃料噴霧Ｆ全体が、キャビティ周壁面１５
又は周壁面１５と底面１６とを滑らかに接続する湾曲し
たコーナー部１７を指向するように設定されている。Fourth, the main injection direction F is set so that the fuel spray F injected near the compression top dead center does not directly interfere with the lower surface of the cylinder head 5 or the peripheral wall surface of the cylinder 2.
1 and the spray angle Fθ are set. More specifically, the upper edge F3 of the fuel spray F is set so as to be inclined horizontally or slightly downward, and the extension of the upper edge F3 is defined by the peripheral wall surface 15 of the cavity 4 near the compression top dead center.
Is set to intersect. That is, the entire fuel spray F near the compression top dead center is
Alternatively, it is set so as to point to a curved corner portion 17 that smoothly connects the peripheral wall surface 15 and the bottom surface 16.

【００４４】この結果、燃料噴霧Ｆがシリンダヘッド
５，シリンダ２，キャビティ４の底面１６や突起部１４
に直接的に干渉することがなく、このような干渉に起因
する排気性能の低下をより確実に防止することができ
る。As a result, the fuel spray F is applied to the cylinder head 5, the cylinder 2, the bottom surface 16 of the cavity 4,
Therefore, it is possible to more reliably prevent the exhaust performance from deteriorating due to such interference.

【００４５】第５に、基準水平面Ｑに平行なピストン冠
面３ａに対し、キャビティ周壁面１５のなす角度βを、
略９０°（直角）に設定している。このため、キャビテ
ィ４内の旋回流分の増速効果及び保持効果が高められ、
その燃焼性能が一段と向上する。Fifth, the angle β formed by the cavity peripheral wall surface 15 with respect to the piston crown surface 3a parallel to the reference horizontal plane Q is expressed as follows:
The angle is set to approximately 90 ° (right angle). Therefore, the speed increasing effect and the holding effect of the swirling flow in the cavity 4 are enhanced,
Its combustion performance is further improved.

【００４６】ここで本実施例においては、主噴射方向Ｆ
１と基準水平面Ｑとのなす角度（１８０−γ）／２も約
１０°程度と非常に小さいため、この主噴射方向Ｆ１と
キャビティ周壁面１５とのなす衝突角度β１も直角に近
い角度（約８０°前後）となる。言い換えると、この衝
突角度β１が直角に近い値となるように設定されてい
る。Here, in the present embodiment, the main injection direction F
Since the angle (180-γ) / 2 between 1 and the reference horizontal plane Q is very small at about 10 °, the collision angle β1 between the main injection direction F1 and the cavity peripheral wall surface 15 is also close to a right angle (about About 80 °). In other words, the collision angle β1 is set to a value close to a right angle.

【００４７】図５は、このような衝突角度（β１）と排
気性能との関係を示している。本実施例のように衝突角
度β１を直角に近い値（約８０°）とすることにより、
例えば衝突角度が４０°の場合に比して、燃料噴霧がキ
ャビティ周壁面１５に衝突した際の燃料噴霧の分散が促
進され、スモーク及びＨＣの排出量が著しく低減される
ことがわかる。FIG. 5 shows the relationship between the collision angle (β1) and the exhaust performance. By setting the collision angle β1 to a value close to a right angle (about 80 °) as in the present embodiment,
For example, compared to the case where the collision angle is 40 °, dispersion of the fuel spray when the fuel spray collides with the cavity peripheral wall surface 15 is promoted, and the amount of smoke and HC emission is significantly reduced.

【００４８】第６に、燃料噴射弁１２の先端部に周方向
に間欠的に配設される噴孔１１の数を、６個以上として
いる。これにより、噴孔１１の数が５個以下の場合に比
して、キャビティ４（燃焼室６）内へ噴射される燃料噴
霧が周方向により均一に拡散される。ここで、本実施例
のようにキャビティ４を浅皿化した場合、キャビティ４
内の旋回成分が相対的に弱められ、燃料噴霧が周方向に
拡散され難い傾向にあるが、上記のように噴孔１１を６
個以上設けることで、燃料噴霧を周方向に十分に拡散さ
せることができ、良好な燃焼性能を維持することができ
る。Sixth, the number of injection holes 11 intermittently arranged in the circumferential direction at the tip of the fuel injection valve 12 is six or more. Thereby, the fuel spray injected into the cavity 4 (combustion chamber 6) is more uniformly diffused in the circumferential direction than in the case where the number of the injection holes 11 is five or less. Here, when the cavity 4 is made shallow as in this embodiment, the cavity 4
Is relatively weakened and fuel spray is less likely to be diffused in the circumferential direction.
By providing more than one fuel spray, the fuel spray can be sufficiently diffused in the circumferential direction, and good combustion performance can be maintained.

【００４９】以上のように、本実施例に係るディーゼル
エンジンの燃焼室構造によれば、キャビティ４の浅皿化
による冷却損失の低減化及び燃費性能の向上を図りつ
つ、燃料噴霧Ｆが突起部１４の傾斜面１３等と干渉する
ことを確実に回避でき、このような干渉に起因する排気
性能の低下を抑制して、良好な燃焼性能を得ることがで
きる。As described above, according to the structure of the combustion chamber of the diesel engine according to the present embodiment, the fuel spray F is projected onto the protrusions while reducing the cooling loss and improving the fuel efficiency by making the cavity 4 shallower. Interference with the inclined surface 13 or the like 14 can be avoided reliably, and a decrease in exhaust performance due to such interference can be suppressed, and good combustion performance can be obtained.

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

【図１】本発明の一実施例に係るディーゼルエンジンの
燃焼室構造を示す断面図。FIG. 1 is a sectional view showing a combustion chamber structure of a diesel engine according to one embodiment of the present invention.

【図２】圧縮上死点付近における燃焼室構造を示す図１
の要部拡大図。FIG. 1 is a diagram showing a combustion chamber structure near a compression top dead center;
FIG.

【図３】キャビティの深さとキャビティ内の縦方向平均
速度との関係を示す説明図。FIG. 3 is an explanatory diagram showing the relationship between the depth of a cavity and the average longitudinal velocity in the cavity.

【図４】上記縦方向平均速度と冷却損失割合との関係を
示す特性図。FIG. 4 is a characteristic diagram showing a relationship between the average speed in the vertical direction and a cooling loss ratio.

【図５】燃料噴霧の衝突角度とＨＣ量及びスモーク量と
の関係を示す特性図。FIG. 5 is a characteristic diagram showing the relationship between the collision angle of fuel spray and the amount of HC and the amount of smoke.

【符号の説明】[Explanation of symbols]

２…シリンダ ３…ピストン ４…キャビティ ６…燃焼室 １２…燃料噴射弁 １４…突起部 2 ... cylinder 3 ... piston 4 ... cavity 6 ... combustion chamber 12 ... fuel injection valve 14 ... protrusion

フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｆ０２Ｍ 61/18 ３６０ Ｆ０２Ｍ 61/18 ３６０Ｊ Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat II (Reference) F02M 61/18 360 F02M 61/18 360J

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】 シリンダ内にピストンが摺動可能に配設
されるとともに、このピストンの冠面の上方に燃焼室が
形成され、この燃焼室が、上記ピストン冠面の略中央部
に略円柱状に凹設されたキャビティを含み、かつ、上記
燃焼室の中央上部に、この燃焼室内へ直接的かつ放射状
に所定の噴霧角で燃料を噴射する燃料噴射弁が配設され
たディーゼルエンジンの燃焼室構造において、 上記キャビティの底面の略中央部に、上方へ略円錐状に
張り出した突起部が形成され、 シリンダ中心線に直交する基準水平面に対し、上記突起
部の傾斜面のなす角度が、圧縮上死点付近で燃料噴射弁
から噴射される燃料噴霧の下縁のなす角度よりも大きく
設定されていることを特徴とするディーゼルエンジンの
燃焼室構造。1. A piston is slidably disposed in a cylinder, and a combustion chamber is formed above a crown surface of the piston. The combustion chamber is substantially circularly formed at a substantially central portion of the piston crown surface. Combustion of a diesel engine including a column-shaped cavity, and a fuel injection valve for directly and radially injecting fuel at a predetermined spray angle into the combustion chamber at the upper center of the combustion chamber. In the chamber structure, a projection projecting upward in a substantially conical shape is formed substantially at the center of the bottom surface of the cavity, and the angle formed by the inclined surface of the projection with respect to a reference horizontal plane orthogonal to the cylinder center line is: A combustion chamber structure for a diesel engine, wherein an angle formed by a lower edge of a fuel spray injected from a fuel injection valve is set near a compression top dead center. 【請求項２】 シリンダ内にピストンが摺動可能に配設
されるとともに、このピストンの冠面の上方に燃焼室が
形成され、この燃焼室が、上記ピストン冠面の略中央部
に略円柱状に凹設されたキャビティを含み、かつ、上記
燃焼室の中央上部に、この燃焼室内へ直接的かつ放射状
に所定の噴霧角で燃料を噴射する燃料噴射弁が配設され
たディーゼルエンジンの燃焼室構造において、 上記キャビティの底面の略中央部に、上方へ略円錐状に
張り出した突起部が形成され、 圧縮上死点付近で燃料噴射弁から噴射される燃料噴霧が
上記突起部と直接的に干渉しないように、上記燃料噴霧
の主噴射方向及び噴霧角が設定されていることを特徴と
するディーゼルエンジンの燃焼室構造。2. A piston is slidably disposed in a cylinder, and a combustion chamber is formed above a crown surface of the piston. The combustion chamber is substantially circularly formed at a substantially central portion of the piston crown surface. Combustion of a diesel engine including a column-shaped cavity, and a fuel injection valve for directly and radially injecting fuel at a predetermined spray angle into the combustion chamber at the upper center of the combustion chamber. In the chamber structure, a projection projecting upward in a substantially conical shape is formed substantially at the center of the bottom surface of the cavity, and the fuel spray injected from the fuel injector near the compression top dead center is directly in contact with the projection. A combustion chamber structure for a diesel engine, wherein the main injection direction and the spray angle of the fuel spray are set so as not to interfere with the fuel spray. 【請求項３】 圧縮上死点付近で燃料噴射弁から噴射さ
れる燃料噴霧が、この燃料噴射弁が取り付けられるシリ
ンダヘッドの下部と干渉しないように、上記燃料噴霧の
主噴射方向及び噴霧角が設定されていることを特徴とす
る請求項１又は２に記載のディーゼルエンジンの燃焼室
構造。3. The main injection direction and the spray angle of the fuel spray are set so that the fuel spray injected from the fuel injection valve near the compression top dead center does not interfere with the lower part of the cylinder head to which the fuel injection valve is attached. The combustion chamber structure for a diesel engine according to claim 1, wherein the combustion chamber is set. 【請求項４】 上記突起部の半径が、上記燃料噴霧の分
裂長さより小さく設定されていることを特徴とする請求
項１〜３のいずれかに記載のディーゼルエンジンの燃焼
室構造。4. The combustion chamber structure for a diesel engine according to claim 1, wherein a radius of the projection is set smaller than a split length of the fuel spray. 【請求項５】 上記キャビティのシリンダ直径に対する
口径比が０．６より大きく設定されているとともに、上
記キャビティの深さがシリンダ直径の１／８より小さく
設定されていることを特徴とする請求項１〜４のいずれ
かに記載のディーゼルエンジンの燃焼室構造。5. The method according to claim 1, wherein the ratio of the diameter of the cavity to the cylinder diameter is set to be larger than 0.6, and the depth of the cavity is set to be smaller than 1/8 of the cylinder diameter. A combustion chamber structure for a diesel engine according to any one of claims 1 to 4. 【請求項６】 上記キャビティの周壁面とピストン冠面
とのなす角度が略９０°に設定されていることを特徴と
する請求項１〜５のいずれかに記載のディーゼルエンジ
ンの燃焼室構造。6. The combustion chamber structure for a diesel engine according to claim 1, wherein an angle between the peripheral wall surface of the cavity and the crown surface of the piston is set to approximately 90 °. 【請求項７】 圧縮上死点付近で燃料噴射弁から噴射さ
れた燃料噴霧が、上記キャビティの周壁面又は周壁面と
底面とを滑らかに接続するコーナー部を指向するように
設定されていることを特徴とする請求項１〜６のいずれ
かに記載のディーゼルエンジンの燃焼室構造。7. The fuel spray injected from the fuel injection valve near the compression top dead center is set so as to be directed to the peripheral wall surface of the cavity or a corner portion that smoothly connects the peripheral wall surface to the bottom surface. The combustion chamber structure of a diesel engine according to any one of claims 1 to 6, wherein: 【請求項８】 上記燃料噴射弁の先端部に、少なくとも
６個以上の噴孔が周方向に間欠的に設けられていること
を特徴とする請求項１〜７のいずれかに記載のディーゼ
ルエンジンの燃焼室構造。8. The diesel engine according to claim 1, wherein at least six or more injection holes are provided intermittently in a circumferential direction at a tip portion of the fuel injection valve. Combustion chamber structure.
JP2000349287A 2000-11-16 2000-11-16 Combustion chamber structure for diesel engine Pending JP2002147240A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2000349287A JP2002147240A (en) 2000-11-16 2000-11-16 Combustion chamber structure for diesel engine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2000349287A JP2002147240A (en) 2000-11-16 2000-11-16 Combustion chamber structure for diesel engine

Publications (1)

Publication Number Publication Date
JP2002147240A true JP2002147240A (en) 2002-05-22

Family

ID=18822723

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2000349287A Pending JP2002147240A (en) 2000-11-16 2000-11-16 Combustion chamber structure for diesel engine

Country Status (1)

Country Link
JP (1) JP2002147240A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008513659A (en) * 2004-09-21 2008-05-01 ダイムラー・アクチェンゲゼルシャフト Internal combustion engine
JP2010077968A (en) * 2008-09-24 2010-04-08 Deere & Co Internal combustion engine with high squish piston
JP2011502226A (en) * 2007-10-30 2011-01-20 ボルボ ラストバグナー アーベー A device that reduces the exhaust of a vehicle combustion engine
JP2012117475A (en) * 2010-12-02 2012-06-21 Isuzu Motors Ltd Structure of combustion chamber of engine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008513659A (en) * 2004-09-21 2008-05-01 ダイムラー・アクチェンゲゼルシャフト Internal combustion engine
US8511271B2 (en) 2004-09-21 2013-08-20 Daimler Ag Internal combustion engine
JP2011502226A (en) * 2007-10-30 2011-01-20 ボルボ ラストバグナー アーベー A device that reduces the exhaust of a vehicle combustion engine
JP2010077968A (en) * 2008-09-24 2010-04-08 Deere & Co Internal combustion engine with high squish piston
JP2012117475A (en) * 2010-12-02 2012-06-21 Isuzu Motors Ltd Structure of combustion chamber of engine

Similar Documents

Publication Publication Date Title
JP4888330B2 (en) Direct injection internal combustion engine
US20050199218A1 (en) Method and apparatus for controlling operation of internal combustion engine, and the internal combustion engine
JP2002276373A (en) Direct injection type internal combustion engine
US6269789B1 (en) Direct fuel injection-type spark-ignition internal combustion engine
EP0656466B1 (en) Combustion chamber structure for diesel engine
JP2002147240A (en) Combustion chamber structure for diesel engine
US4191136A (en) Combustion chamber of an internal combustion engine
EP1707783A1 (en) Spark ignition direct injection internal combustion engine control
JPS59201922A (en) Construction of auxiliary combustion chamber of diesel engine
JPH11190217A (en) Direct injection type diesel engine
JP4115549B2 (en) Direct-injection spark ignition internal combustion engine
JPS63120815A (en) Fuel injection type internal combustion engine with external ignition
JP4048937B2 (en) In-cylinder direct injection internal combustion engine
JP7487595B2 (en) Spark plug for internal combustion engine and internal combustion engine
US4532898A (en) Fuel injection type internal combustion engine
JP3280431B2 (en) In-cylinder fuel injection engine
US20230046872A1 (en) Combustion system
JPH10141062A (en) Diesel engine
JP4096637B2 (en) In-cylinder direct injection internal combustion engine
JP4026406B2 (en) Direct-injection spark ignition internal combustion engine
CN110446835B (en) Spark ignition type internal combustion engine
JP2006328961A (en) Fuel injection control device for compression ignition internal combustion engine
JP2000297645A (en) Direct-injection diesel engine
JP2683968B2 (en) Diesel engine swirl chamber
JP2003314286A (en) Cylinder injection type spark ignition engine