JP3726503B2 - Direct-injection spark ignition internal combustion engine - Google Patents

Direct-injection spark ignition internal combustion engine Download PDF

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Publication number
JP3726503B2
JP3726503B2 JP20187698A JP20187698A JP3726503B2 JP 3726503 B2 JP3726503 B2 JP 3726503B2 JP 20187698 A JP20187698 A JP 20187698A JP 20187698 A JP20187698 A JP 20187698A JP 3726503 B2 JP3726503 B2 JP 3726503B2
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combustion
valve
swirl
tumble
engine
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JPH11257078A (en
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章彦 角方
保憲 岩切
康治 平谷
尚志 青山
和喜 荒巻
祐一 入矢
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Nissan Motor Co Ltd
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    • 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
    • F02F1/42—Shape or arrangement of intake or exhaust channels in cylinder heads
    • F02F1/4214—Shape or arrangement of intake or exhaust channels in cylinder heads specially adapted for four or more valves per cylinder
    • 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
    • F02B23/08—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition
    • F02B23/10—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder
    • F02B23/104—Other engines characterised by special shape or construction of combustion chambers to improve operation with positive ignition with separate admission of air and fuel into cylinder the injector being placed on a side position of the cylinder
    • 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
    • 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
    • F02B2275/48—Tumble motion in gas movement in cylinder
    • 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
    • F02F2001/245—Arrangement of valve stems in cylinder heads the valve stems being orientated at an angle 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
  • Combustion Methods Of Internal-Combustion Engines (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料噴射弁から燃焼室内に直接燃料を噴射し、点火栓により点火する直噴火花点火式内燃機関に関する。
【０００２】
【従来の技術】
従来の直噴火花点火式内燃機関として、例えば特開平６−８１６５１号公報に開示されているものがある。
このものでは、吸気ポートの下側に燃料噴射弁があり、ピストン冠面の吸気側に凹部があり、この凹部の燃焼室中心側の縁部の延長線上に点火栓が配設されている。そして、吸気ポートは、燃焼室内に逆タンブル（すなわち吸入空気がシリンダ壁に沿って下方に燃料噴射弁の噴射方向線の上流側を横切って流れた後、ピストン冠面の凹部で曲げられて、燃焼室中心部を上方に燃料噴射弁の噴射方向線の下流側を横切って流れて、点火栓に至るようなガス流動）を生成するように設定されている。
【０００３】
ここにおいて、低負荷時は圧縮行程にて燃料噴射し（成層燃焼）、高負荷時は吸気行程にて燃料噴射する（均質燃焼）。圧縮行程噴射（成層燃焼）では、燃料噴射弁より噴射された燃料は、すぐさま吸気流に乗って、ピストン冠面に衝突し、筒内に生成された逆タンブルによって、点火栓に向けて、徐々に気化しながら輸送される。
【０００４】
【発明が解決しようとする課題】
しかしながら、このような従来の直噴火花点火式内燃機関では、圧縮行程噴射（成層燃焼）時に、ピストン冠面に衝突した燃料が液膜を形成し、排気ガス中のスモークやＨＣ生成の要因になったり、液膜がデポジットとして堆積し、はがれたデポジットによって吸排気弁への噛込み等の不具合を発生したりするという問題点があった。
【０００５】
本発明は、このような従来の問題点に鑑み、筒内ガス流動を様々に変化可能として、成層燃焼時の燃料輸送経路の最適化等を図ることを目的とする。
【０００６】
【課題を解決するための手段】
このため、請求項１に係る発明では、燃料噴射弁から燃焼室内に直接燃料を噴射し、点火栓により点火する直噴火花点火式内燃機関において、吸入空気の流れを左右方向に偏らせて燃焼室内にスワールを生成することができるスワール強化手段と、吸入空気の流れを上下方向に偏らせて燃焼室内にタンブルを生成することができるタンブル強化手段と、前記スワール強化手段の作動と前記タンブル強化手段の作動とを制御するガス流動制御手段と、機関の運転条件が所定の成層燃焼運転領域内にあるときに前記燃料噴射弁からの燃料噴射を圧縮行程に行う成層燃焼と、機関の運転条件が所定の均質燃焼運転領域内にあるときに前記燃料噴射弁からの燃料噴射を吸気行程に行う均質燃焼とを制御する燃焼制御手段と、スワール強化時に混合気を形成する凹部を冠面に形成したピストンと、を備え、前記ガス流動制御手段は、前記成層燃焼が行われるときであって、かつ、所定のアイドル運転または機関の運転条件が所定の低回転低負荷領域内であるとき、および、前記均質燃焼が 行われるときであって、かつ、比較的低回転領域であるときに、前記スワール強化手段を作動させる一方、前記成層燃焼が行われるときであって、かつ、所定のアイドル運転または機関の運転条件が所定の低回転負荷領域内でないとき、および、前記均質燃焼が行われるときであって、かつ、比較的低回転領域でないときに、前記タンブル強化手段を作動させることを特徴とする。
【０００７】
請求項２に係る発明では、前記スワール強化手段は、各気筒毎の吸気通路に設けられて、閉弁時に吸気通路断面の一部のみを連通させる左右非対称な切欠きを有するスワール用開閉弁であり、前記タンブル強化手段は、各気筒毎の吸気通路に設けられて、閉弁時に吸気通路断面の一部のみを連通させる左右対称な切欠きを有するタンブル用開閉弁であることを特徴とする。
【０００８】
請求項３に係る発明では、前記スワール強化手段及び前記タンブル強化手段は、各気筒毎の吸気通路に設けられた第１開閉弁と、この第１開閉弁上流から分岐して第１開閉弁下流に合流する左右対称な２本のサブポートと、一方のサブポートに設けられた第２開閉弁とを含んで構成されることを特徴とする。
請求項４に係る発明では、燃料噴射弁の噴射方向を吸気弁下方位置から燃焼室内にガス流動がない状態で点火栓を直撃しない方向に設定したことを特徴とする。
【０００９】
請求項５に係る発明では、ピストン冠面に形成した凹部は、機関前後方向に中心線を持つ円筒面からなることを特徴とする。
請求項６に係る発明では、ピストン冠面上に、吸気弁側に偏心し、略点火栓下にて立上がる壁を有する円形状のボール型燃焼室を形成すると共に、略点火栓下から排気弁側にかけて２つの吸気弁の中心を結ぶ線と略平行に長手方向中心線を持つ円筒面にて形成された円筒型燃焼室を形成したことを特徴とする。
請求項７に係る発明では、前記ガス流動制御手段は、前記燃焼制御手段により成層燃焼が行われるときであって、かつ、所定のアイドル運転が行われるときに前記スワール強化手段を作動させ、前記燃焼制御手段により成層燃焼が行われるときであって、かつ、所定のアイドル運転が行われないときに前記タンブル強化手段を作動させることを特徴とする。
【００１０】
請求項８に係る発明では、請求項１〜請求項７に係る発明において、前記ガス流動制御手段は、前記燃焼制御手段により成層燃焼が行われるときであって、かつ、機関の暖機が完了していないときに、強制的に前記スワール強化手段を作動させることを特徴とする。
【００１１】
【発明の効果】
請求項１に係る発明によれば、スワール強化手段とタンブル強化手段とを設けるようにしたため、機関の運転条件によって、筒内ガス流動を変化させ、成層燃焼時の燃料輸送経路を制御することが可能になる。また、タンブル流動にすることにより、成層燃焼が可能となり、スワール流動にすることにより、混合気のミキシングを制御できる。
また、ピストン冠面に凹部を設けたことにより、成層燃焼時にスワールを生成した場合に、ピストン凹部に燃料噴射することで、気化した混合気を点火栓に輸送できて、良好な成層燃焼が可能となり、これにより冷間始動時などの点火栓のくすぶりを回避できる。
また、成層燃焼と均質燃焼とを制御する燃焼制御手段と、スワール強化手段及びタンブル強化手段の各作動を制御するガス流動制御手段とを設けることで、最適な組み合わせで制御でき、成層燃焼運転領域において、順タンブルによって燃料噴霧を点火栓回りに導くエアガイドコンセプトで成層燃焼を実現し、均質燃焼運転領域において、スワールによって燃焼の安定化を図ることで、良好な成層燃焼と良好な均質燃焼を実現可能となる。
また、特に成層燃焼運転領域での低回転低負荷域のみスワールコンセプトとすることで、スワール保存用の凹部（ボール型燃焼室）の深さを浅くでき、全開時等の均質燃焼運転 領域においても十分な性能を維持できる。
また、特に成層燃焼運転領域での低回転域のみスワールコンセプトとすることで、スワール保存用の凹部（ボール型燃焼室）の深さを浅くでき、全開時等の均質燃焼運転領域においても十分な性能を維持できる。
また、均質燃焼の場合に、スワールによって燃焼の安定化を図ることで、良好な均質燃焼を実現できる。
【００１２】
請求項２に係る発明によれば、スワール強化手段及びタンブル強化手段として、互いに切欠きが異なる開閉弁を用いることにより、切欠き形状を変えるだけで流動の形態を変えることが可能なため、他の機関にも展開が容易であり、かつ、開度を制御することで容易に流動強さを制御できる。
請求項３に係る発明によれば、１本のサブポートから吸入空気を導入することでスワールを生成し、２本のサブポートから吸入空気を導入することでタンブルを生成でき、しかもより強い流動を生成可能となる。
【００１３】
請求項４に係る発明によれば、燃料噴射弁の噴射方向を点火栓を直撃しない方向に設定したことにより、冷間時の液滴燃料の点火栓への直撃を回避できる。
請求項５に係る発明によれば、ピストン冠面に機関前後方向に中心線を持つ円筒面からなる凹部を設けたことにより、タンブルの効果的な保存が可能となり、低回転時のように流動が弱い場合にも、燃料の点火栓への輸送を確実にすることができる。
【００１４】
請求項６に係る発明によれば、ピストン冠面上にスワール保存用のボール型燃焼室とタンブル保存用の円筒型燃焼室とを形成することで、機関運転のあらゆる領域で良好な性能を発揮することが可能である。
請求項７に係る発明によれば、順タンブルによって成層燃焼を実現する際に筒内流動が弱い領域においては点火栓回りに噴霧を導くのが難しい場合があることから、成層燃焼運転領域において、機関運転状態に応じてスワールとタンブルとを切換え、スワールによって燃料噴霧を点火栓回りに導いて成層燃焼を実現するスワールコンセプトによる成層燃焼とエアガイドコンセプト（順タンブル）による成層燃焼とを使い分けることで、成層燃焼運転領域の全域において良好な成層燃焼が可能となり、特に成層燃焼運転領域でのアイドル運転時のみスワールコンセプトとすることで、スワール保存用の凹部（ボール型燃焼室）の深さを浅くでき、全開時等の均質燃焼運転領域においても十分な性能を維持できる。
【００１５】
請求項８に係る発明によれば、成層燃焼の場合に、冷間始動時はスワールを生成し、暖機完了後にタンブルを生成するように切換えることにより、冷間時の液滴燃料の点火栓への直撃を回避できる。
【００１６】
【発明の実施の形態】
以下に本発明の実施の形態を図面に基づいて説明する。
図１は本発明の第１実施例を示す機関の概略平面図及び縦断面図である。
図１において、１はシリンダヘッド、２はシリンダブロック、３はピストン、４はこれらにより形成される燃焼室である。ピストン３の冠面には、その吸気側に偏心した位置に中心を持つ円形の凹部（ボール型燃焼室）１６を設けている（図２に示すピストン３の平面図を参照）。
【００１７】
燃焼室４の上面側（シリンダヘッド１側）には、略中央に点火栓５が設けられ、また、これを取り囲むように、一方の側に２つの吸気弁６Ａ，６Ｂ、他方の側に２つの排気弁７Ａ，７Ｂが設けられている。
吸入空気は、各気筒毎の吸気通路８により導かれ、吸気通路８がシリンダヘッド１内で左右２本の吸気ポートに分岐して、各吸気弁６Ａ，６Ｂより燃焼室４内に吸入される。排気は、排気弁７Ａ，７Ｂより排気通路９へ排出される。
【００１８】
燃料噴射弁１０は、吸気弁６Ａ，６Ｂ間でこれらの下方位置より燃焼室４内を指向しており、その噴射方向は、ガス流動がない状態で燃料噴霧が点火栓５を直撃しないように、点火栓５より下側の延長線上に向けられている。
ここにおいて、各気筒毎の吸気通路８に、スワール強化手段としてのスワール用開閉弁１１と、タンブル強化手段としてのタンブル用開閉弁１２とが、直列に設けられている。
【００１９】
スワール用開閉弁１１は、バタフライ弁であり、図３（ａ）に示すように弁体の上側半分に切欠き（左右非対称な切欠き）１１ａが設けられている。これにより、閉弁時に、吸気通路断面の上側半分のみを連通させて、燃焼室４内にスワールを生成することができる。
タンブル用開閉弁１２は、同じくバタフライ弁であるが、図３（ｂ）に示すように弁体の上側部分に切欠き（左右対称な切欠き）１２ａが設けられている。これにより、閉弁時に、吸気通路断面の上側部分のみを連通させて、燃焼室４内にタンブルを生成することができる。
【００２０】
このタンブルは、図１に示してあるように、順タンブルである。すなわち、吸入空気が燃焼室４の上面側（シリンダヘッド１側）に沿って流れ、次いで下方へ燃料噴射弁１０の噴射方向線の下流側を横切って流れ、ピストン３の冠面で反転した後、上方へ燃料噴射弁１０の噴射方向線の上流側を横切って流れて、点火栓５に至るようなガス流動である。
【００２１】
これらのスワール用開閉弁１１及びタンブル用開閉弁１２は、図４に示すように、それぞれ、モータ等のアクチュエータ１３，１４により駆動され、各アクチュエータ１３，１４は、機関制御用コントロールユニット１５により機関運転条件に応じて制御されるようになっている。
ここにおいて、コントロールユニット１５は、前記燃料噴射弁１０からの燃料噴射を圧縮行程に行う成層燃焼と前記燃料噴射弁１０からの燃料噴射を吸気行程に行う均質燃焼とを制御する燃焼制御手段としての機能、及び、前記スワール強化手段（スワール用開閉弁１１）の作動と前記タンブル強化手段（タンブル用開閉弁１２）の作動とを制御するガス流動制御手段としての機能、を備える。
【００２２】
次に機関運転条件に応じてスワールとタンブルとを切換える場合について説明する。
図５〜図７に示した制御用マップでは、成層燃焼（成層リーン燃焼）運転領域内で、機関運転状態に応じてスワールとタンブル（順タンブル強化によるエアガイドコンセプト）とを切換えるようにしている。
【００２３】
順タンブルによって成層燃焼を実現する際に筒内流動が弱い領域においては点火栓回りに噴霧を導くのが難しい場合があることから、成層燃焼運転領域において、機関運転状態に応じてスワールとタンブルとを切換え、低回転低負荷側ではスワールコンセプトによる成層燃焼、高回転高負荷側ではエアガイドコンセプト（順タンブル）による成層燃焼とすることで、成層燃焼運転領域の全域にわたって良好な成層燃焼が可能となる。また、ピストン冠面に形成するスワール保存用の凹部（ボール型燃焼室）１６を浅くすることが可能となり、均質燃焼運転領域においても十分な性能を維持でき（均質燃焼時に筒内の流動や乱れ強さを十分に確保でき）、全開性能も向上する。
【００２４】
図５に示した制御用マップでは、成層燃焼運転領域でのアイドル運転状態においてのみ、スワールにより成層燃焼を実現している。
図６に示した制御用マップでは、成層燃焼運転領域での低回転低負荷域において、スワールにより成層燃焼を実現している。
図７に示した制御用マップでは、成層燃焼運転領域での低回転域において、スワールにより成層燃焼を実現している。
【００２５】
また、冷間始動時において、低回転・低負荷での成層燃焼（成層リーン燃焼）運転領域では、水温センサからの信号に基づき、スワール用開閉弁１１を閉じてスワールを生成し、暖機完了後に筒内ガス流動を強タンブルとするようにタンブル用開閉弁１２を閉じてタンブルを生成するように切換える。
【００２６】
また、この領域よりやや高回転側の均質リーン燃焼運転領域では、筒内ガス流動をスワールとするように、スワール用開閉弁１１を閉じる。
更に、これら以外の高回転・高負荷での均質ストイキ（又はリッチ）燃焼運転領域では、筒内ガス流動を弱タンブルとするように、タンブル用開閉弁１２を少なくとも半開状態まで閉じる。
【００２７】
ここで、図８は、成層燃焼時のスワールによる燃料の挙動を示す模式図である。
図８に示すように、成層燃焼での冷間始動時に、スワール用開閉弁１１を閉じて、燃焼室４内、特にピストン３の冠面の凹部１６内にスワールを生成し、その凹部１６内に燃料噴射弁１０から燃料を噴射することにより、凹部１６内に形成されたスワール流動の作用で、ピストン３の冠面にて気化を促進された燃料を点火栓５に輸送でき、くすぶることなく成層燃焼が可能となる。
【００２８】
図９は成層燃焼時のタンブルによる燃料の挙動を示す模式図である。
成層燃焼時（圧縮行程噴射時）は、タンブル用開閉弁１２を閉じて、筒内ガス流動を強タンブルとする。圧縮行程にて燃料噴射弁１０から噴射された燃料は、ピストン３の冠面にて反転した後の燃焼室４上側へ向かうタンブルにより、燃焼室４上側へと偏向され、広がりながら点火栓５へ到達して、着火される。従って、燃料がピストン３の冠面を経由しないため、液膜をほとんど生じることがなく、スモーク、ＨＣの発生、及びデポジットの堆積を抑制できる。
【００２９】
但し、冷間始動時は、スワール流動として、暖機完了後に強タンブルに切換える。これにより、機関始動時の混合分布を改善すると共に、点火栓５がくすぶることなく、成層燃焼が可能となる。
この実施例では、切欠き形状を変えることにより、流動の形態を変えることができるため、他の機関にも展開が容易であり、かつ、開度を制御することにより、容易に流動強さを制御できる。
【００３０】
図１０は本発明の第２実施例を示す機関の縦断面図、図１１はこの場合のピストンの平面図である。
この第２実施例では、ピストン３の冠面に、機関前後方向に中心線を持つ円筒面からなる凹部（円筒型燃焼室）１７を設けている。その他は第１実施例と同じである。
【００３１】
これにより、筒内に形成されたタンブルを圧縮行程後半まで効率良く保存することができるため、タンブルにより燃料を上方に偏向して点火栓５に輸送でき、安定した成層燃焼が可能となる。
図１２は本発明の第３実施例を示す機関の縦断面図である。
この第３実施例では、ピストン３の冠面上に、吸気弁６Ａ，６Ｂ側に偏心し、略点火栓５下にて立上がる壁１８ａを有する円形状で浅皿のボール型燃焼室１８を形成すると共に、略点火栓５下から排気弁７Ａ，７Ｂ側にかけて２つの吸気弁６Ａ，６Ｂの中心を結ぶ線と略平行に長手方向中心線を持つ円筒面にて形成された円筒型燃焼室１９を形成してある。その他は第１実施例と同じである。
【００３２】
このように、ピストン３の冠面上にスワール保存用のボール型燃焼室１８とタンブル保存用の円筒型燃焼室１９とを形成することで、機関運転のあらゆる領域で良好な性能を発揮することが可能である。
図１３は本発明の第４実施例を示す機関の概略平面図及び縦断面図である。
この第４実施例では、各気筒毎の吸気通路８に第１開閉弁２１を設けてある。また、この第１開閉弁２１上流から上側に分岐して第１開閉弁２１下流（吸気弁６Ａ，６Ｂ直上流）に合流する左右対称な２本のサブポート２２Ａ，２２Ｂを設けてある。そして、一方のサブポート２２Ｂの途中に第２開閉弁２３を設けてある。これらがスワール強化手段及びタンブル強化手段に相当する。
【００３３】
この場合、第１開閉弁２１を閉じた状態で、第２開閉弁２３を閉じることにより、サブポート２２Ａのみから左右非対称に吸入空気を導入することにより、スワールを生成することができる。
また、第１開閉弁２１を閉じた状態で、第２開閉弁２３を開くことにより、両方のサブポート２２Ａ，２２Ｂから左右対称に吸入空気を導入し、サブポート２２Ａ，２２Ｂにより吸入空気の流れを上下方向に偏らせることで、タンブルを生成することができる。
【００３４】
これにより、より強いガス流動を筒内に生成することができ、タンブルにより燃料を上方に偏向して点火栓５へ輸送でき、より安定した成層燃焼が可能となる。
尚、この第４実施例では、ピストン３の冠面に第１実施例と同様の凹部（ボール型燃焼室）１６を設けているが、第２実施例と同様な凹部１７（円筒型燃焼室）を設けてもよいし、第３実施例と同様にボール型燃焼室１８と円筒型燃焼室１９とを設けてもよい。
【図面の簡単な説明】
【図１】 本発明の第１実施例を示す機関の概略平面図及び縦断面図
【図２】 同上のピストンの平面図
【図３】 スワール用開閉弁及びタンブル用開閉弁の切欠き形状を示す図
【図４】 制御システムの概略図
【図５】 制御用マップを示す図
【図６】 制御用マップを示す図
【図７】 制御用マップを示す図
【図８】 成層燃焼時のスワールによる燃料の挙動を示す模式図
【図９】 成層燃焼時のタンブルによる燃料の挙動を示す模式図
【図 10 】 本発明の第２実施例を示す機関の縦断面図
【図 11 】 同上のピストンの平面図
【図 12 】 本発明の第３実施例を示す機関の縦断面図
【図 13 】 本発明の第４実施例を示す機関の概略平面図及び縦断面図
【符号の説明】
１ シリンダヘッド
２ シリンダブロック
３ ピストン
４ 燃焼室
５ 点火栓
６Ａ，６Ｂ 吸気弁
７Ａ，７Ｂ 排気弁
８ 吸気通路
９ 排気通路
１０ 燃料噴射弁
１１ スワール用開閉弁
１１ａ 切欠き
１２ タンブル用開閉弁
１２ａ 切欠き
１３ アクチュエータ
１４ アクチュエータ
１５ コントロールユニット（燃焼制御手段及びガス流動制御手段）
１６ 凹部（ボール型燃焼室）
１７ 凹部（円筒型燃焼室）
１８ ボール型燃焼室
１９ 円筒型燃焼室
２１ 第１開閉弁
２２Ａ，２２Ｂ サブポート
２３ 第２開閉弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct injection spark ignition internal combustion engine in which fuel is directly injected into a combustion chamber from a fuel injection valve and ignited by a spark plug.
[0002]
[Prior art]
As a conventional direct injection spark ignition type internal combustion engine, for example, there is one disclosed in JP-A-6-81651.
In this configuration, a fuel injection valve is provided below the intake port, a recess is provided on the intake side of the piston crown surface, and an ignition plug is disposed on an extension line of an edge of the recess on the center side of the combustion chamber. Then, the intake port is inversely tumbled into the combustion chamber (that is, the intake air flows downward along the cylinder wall across the upstream side of the injection direction line of the fuel injection valve, and is then bent at the recess of the piston crown surface. It is set so as to generate a gas flow that flows upward in the center of the combustion chamber across the downstream side of the injection direction line of the fuel injection valve and reaches the spark plug.
[0003]
Here, fuel injection is performed during the compression stroke during the low load (stratified combustion), and fuel injection is performed during the intake stroke during the high load (homogeneous combustion). In compression stroke injection (stratified combustion), the fuel injected from the fuel injection valve immediately takes the intake flow, collides with the crown of the piston, and gradually toward the spark plug by the reverse tumble generated in the cylinder. It is transported while vaporizing.
[0004]
[Problems to be solved by the invention]
However, in such a conventional direct-injection spark-ignition internal combustion engine, at the time of compression stroke injection (stratified combustion), the fuel that collided with the piston crown forms a liquid film, which causes smoke and HC generation in the exhaust gas. There is a problem that the liquid film accumulates as a deposit, and the peeled deposit causes problems such as biting into the intake and exhaust valves.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to optimize the fuel transportation route during stratified combustion by changing the in-cylinder gas flow in various ways.
[0006]
[Means for Solving the Problems]
Therefore, in the invention according to claim 1, in the direct injection spark ignition internal combustion engine in which fuel is directly injected from the fuel injection valve into the combustion chamber and ignited by the spark plug, combustion is performed by biasing the flow of intake air in the left-right direction. Swirl strengthening means capable of generating swirl in the chamber, tumble strengthening means capable of generating tumble in the combustion chamber by biasing the flow of intake air in the vertical direction, operation of the swirl strengthening means, and tumble strengthening Gas flow control means for controlling the operation of the means, stratified combustion for performing fuel injection from the fuel injection valve during the compression stroke when the engine operating conditions are within a predetermined stratified combustion operation region, and engine operating conditions Combustion control means for controlling the homogeneous combustion in which the fuel injection from the fuel injection valve is performed in the intake stroke when the fuel is in a predetermined homogeneous combustion operation region, and the air-fuel mixture at the time of swirl strengthening The gas flow control means is when the stratified combustion is performed, and the predetermined idle operation or the engine operating condition is a predetermined low rotation and low speed. When it is within the load region and when the homogeneous combustion is performed and when it is in a relatively low rotation region, the swirl strengthening means is operated while the stratified combustion is performed. And when the predetermined idle operation or the engine operating condition is not within a predetermined low rotation load region, and when the homogeneous combustion is performed and is not in a relatively low rotation region, the tumble The reinforcing means is operated .
[0007]
In the invention according to claim 2, the swirl strengthening means is a swirl opening / closing valve provided in an intake passage for each cylinder and having a left-right asymmetric cutout for communicating only a part of the cross section of the intake passage when the valve is closed. The tumble reinforcing means is a tumble on / off valve provided in an intake passage for each cylinder and having a symmetric notch for communicating only a part of the cross section of the intake passage when the valve is closed. .
[0008]
In the invention according to claim 3, the swirl strengthening means and the tumble strengthening means include a first on-off valve provided in an intake passage for each cylinder and a first on-off valve downstream from the first on-off valve. It is characterized by including two symmetrical left-and-right subports that merge with each other and a second on-off valve provided in one of the subports.
The invention according to claim 4 is characterized in that the injection direction of the fuel injection valve is set to a direction in which there is no gas flow in the combustion chamber from the lower position of the intake valve so as not to hit the spark plug directly.
[0009]
The invention according to claim 5 is characterized in that the recess formed in the piston crown surface is formed of a cylindrical surface having a center line in the longitudinal direction of the engine .
In the invention according to claim 6 , a circular ball-shaped combustion chamber having a wall that is eccentric to the intake valve side and rises substantially under the spark plug is formed on the piston crown surface, and the exhaust gas is substantially exhausted from under the spark plug. A cylindrical combustion chamber formed by a cylindrical surface having a longitudinal center line substantially parallel to a line connecting the centers of two intake valves toward the valve side is formed.
In the invention according to claim 7, wherein the gas flow control means is a is when stratified charge combustion is performed by the combustion control means, and actuates the swirl reinforcing means when the predetermined idle operation is performed, the The tumble strengthening means is operated when stratified combustion is performed by the combustion control means and when a predetermined idle operation is not performed.
[0010]
In the invention according to claim 8 , in the invention according to claims 1 to 7 , the gas flow control means is a time when stratified combustion is performed by the combustion control means, and warming up of the engine is completed. The swirl strengthening means is forcibly activated when not.
[0011]
【The invention's effect】
According to the first aspect of the present invention, since the swirl strengthening means and the tumble strengthening means are provided, it is possible to change the in-cylinder gas flow and control the fuel transport path during stratified combustion according to the operating conditions of the engine. It becomes possible. In addition, stratified combustion is possible by making the tumble flow, and mixing of the air-fuel mixture can be controlled by making the swirl flow.
In addition, when swirls are generated during stratified combustion by providing a recess on the piston crown, fuel injection into the piston recess allows the vaporized mixture to be transported to the spark plug, enabling good stratified combustion Thus, smoldering of the spark plug at the time of cold start or the like can be avoided.
Further, by providing combustion control means for controlling stratified combustion and homogeneous combustion, and gas flow control means for controlling the operations of the swirl strengthening means and the tumble strengthening means, it is possible to control in an optimum combination, and the stratified charge combustion operation region In, stratified combustion is realized with an air guide concept that guides fuel spray around the spark plug by forward tumble, and in the homogeneous combustion operation region, stabilization of combustion is achieved by swirl to achieve good stratified combustion and good homogeneous combustion It becomes feasible.
In addition, by adopting the swirl concept only in the low-rotation low-load region in the stratified combustion operation region, the depth of the swirl storage recess (ball-type combustion chamber) can be reduced, and even in the homogeneous combustion operation region such as when fully open Sufficient performance can be maintained.
In addition, by adopting the swirl concept only in the low rotation range in the stratified combustion operation region, the depth of the swirl storage recess (ball-type combustion chamber) can be reduced, which is sufficient even in the homogeneous combustion operation region such as when fully open. Performance can be maintained.
In the case of homogeneous combustion, good homogeneous combustion can be realized by stabilizing the combustion by swirl.
[0012]
According to the second aspect of the present invention, since the on / off valves having different notches are used as the swirl strengthening means and the tumble strengthening means, the flow form can be changed only by changing the notch shape. The engine can be easily developed, and the flow strength can be easily controlled by controlling the opening degree.
According to the invention of claim 3, swirl can be generated by introducing intake air from one subport, tumble can be generated by introducing intake air from two subports, and a stronger flow can be generated. It becomes possible.
[0013]
According to the fourth aspect of the present invention, since the injection direction of the fuel injection valve is set to a direction that does not directly hit the spark plug, it is possible to avoid direct hit of the droplet fuel on the spark plug when cold.
According to the fifth aspect of the present invention, by providing the piston crown surface with the concave portion formed of the cylindrical surface having the center line in the longitudinal direction of the engine, it is possible to effectively store the tumble, and the fluid flows at the time of low rotation. Even when the fuel is weak, the transportation of the fuel to the spark plug can be ensured.
[0014]
According to the sixth aspect of the present invention, the ball-shaped combustion chamber for storing swirls and the cylindrical combustion chamber for storing tumble are formed on the piston crown surface, thereby achieving good performance in all areas of engine operation. Is possible.
According to the seventh aspect of the invention, when stratified combustion is realized by forward tumble, it may be difficult to guide the spray around the spark plug in a region where the in-cylinder flow is weak. By switching between swirl and tumble according to the engine operating condition, and using stratified combustion by swirl concept that realizes stratified combustion by directing fuel spray around spark plug by swirl and stratified combustion by air guide concept (forward tumble) Good stratified combustion is possible in the entire stratified combustion operation region, and by using the swirl concept only during idle operation in the stratified combustion operation region, the depth of the swirl storage recess (ball-type combustion chamber) is shallow. It is possible to maintain sufficient performance even in a homogeneous combustion operation region such as when fully open.
[0015]
According to the eighth aspect of the present invention, in the case of stratified combustion, by switching to generate a swirl at the time of cold start and to generate a tumble after completion of warm-up, the spark plug of the droplet fuel at the time of cold Avoid direct hits.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic plan view and longitudinal sectional view of an engine showing a first embodiment of the present invention.
In FIG. 1, 1 is a cylinder head, 2 is a cylinder block, 3 is a piston, and 4 is a combustion chamber formed by these. A circular recess (ball-type combustion chamber) 16 having a center at a position eccentric to the intake side is provided on the crown surface of the piston 3 (see a plan view of the piston 3 shown in FIG. 2).
[0017]
On the upper surface side (cylinder head 1 side) of the combustion chamber 4, an ignition plug 5 is provided substantially in the center, and two intake valves 6 </ b> A and 6 </ b> B are provided on one side and 2 on the other side so as to surround it. Two exhaust valves 7A and 7B are provided.
The intake air is guided by the intake passage 8 for each cylinder, and the intake passage 8 branches into the left and right intake ports in the cylinder head 1 and is sucked into the combustion chamber 4 from the intake valves 6A and 6B. . Exhaust gas is discharged into the exhaust passage 9 through the exhaust valves 7A and 7B.
[0018]
The fuel injection valve 10 is directed to the inside of the combustion chamber 4 from the lower position between the intake valves 6A and 6B, and the injection direction is such that the fuel spray does not directly hit the spark plug 5 in the absence of gas flow. , Directed to an extension line below the spark plug 5.
Here, a swirl on / off valve 11 as a swirl strengthening means and a tumble on / off valve 12 as a tumble strengthening means are provided in series in the intake passage 8 for each cylinder.
[0019]
The swirl on-off valve 11 is a butterfly valve . As shown in FIG. 3A, a notch (asymmetrical notch) 11a is provided in the upper half of the valve body. As a result, when the valve is closed, only the upper half of the cross section of the intake passage can be communicated to generate a swirl in the combustion chamber 4.
The tumble on / off valve 12 is also a butterfly valve, but as shown in FIG. 3B , a notch (a symmetric notch) 12a is provided in the upper part of the valve body. As a result, when the valve is closed, only the upper part of the cross section of the intake passage can be communicated to generate a tumble in the combustion chamber 4.
[0020]
This tumble is a forward tumble, as shown in FIG. That is, the intake air flows along the upper surface side (cylinder head 1 side) of the combustion chamber 4, then flows downward across the downstream side of the injection direction line of the fuel injection valve 10, and reverses at the crown surface of the piston 3. The gas flow is such that it flows across the upstream side of the injection direction line of the fuel injection valve 10 and reaches the spark plug 5.
[0021]
As shown in FIG. 4 , the swirl on / off valve 11 and the tumble on / off valve 12 are driven by actuators 13 and 14 such as motors, respectively. The actuators 13 and 14 are engine-controlled by an engine control control unit 15. It is controlled according to the operating conditions.
Here, the control unit 15 serves as combustion control means for controlling stratified combustion in which fuel injection from the fuel injection valve 10 is performed in a compression stroke and homogeneous combustion in which fuel injection from the fuel injection valve 10 is performed in an intake stroke. And a function as gas flow control means for controlling the operation of the swirl strengthening means (swirl on-off valve 11) and the operation of the tumble strengthening means (tumble on-off valve 12).
[0022]
Next, the case of switching between swirl and tumble according to engine operating conditions will be described.
In the control map shown in FIGS. 5 to 7, swirl and tumble (air guide concept by forward tumble strengthening) are switched in accordance with the engine operating state in the stratified combustion (stratified lean combustion) operation region. .
[0023]
When stratified combustion is realized by forward tumble, it may be difficult to guide the spray around the spark plug in the region where the in-cylinder flow is weak.Therefore, in the stratified combustion operation region, swirl and tumble Stratified combustion by the swirl concept on the low rotation and low load side, and stratified combustion by the air guide concept (forward tumble) on the high rotation and high load side, enabling good stratified combustion over the entire stratified combustion operation range Become. Further, it becomes possible to shallow the swirl storage recess (ball-type combustion chamber) 16 formed on the piston crown surface, so that sufficient performance can be maintained even in the homogeneous combustion operation region (flow and turbulence in the cylinder during homogeneous combustion). Strength can be secured sufficiently) and the fully open performance is improved.
[0024]
In the control map shown in FIG. 5, stratified combustion is realized by swirl only in the idle operation state in the stratified combustion operation region.
In the control map shown in FIG. 6, stratified combustion is realized by swirl in the low rotation and low load region in the stratified combustion operation region.
In the control map shown in FIG. 7, stratified combustion is realized by swirl in the low rotation region in the stratified combustion operation region.
[0025]
Also, at the time of cold start, in the stratified charge combustion (stratified lean combustion) operation region at low rotation and low load, the swirl on-off valve 11 is closed based on the signal from the water temperature sensor to complete the warm-up. Later, the tumble on / off valve 12 is closed so as to generate a tumble so that the in-cylinder gas flow becomes a strong tumble.
[0026]
In the homogeneous lean combustion operation region slightly higher than this region, the swirl on-off valve 11 is closed so that the in-cylinder gas flow is swirled.
Furthermore, in the homogeneous stoichiometric (or rich) combustion operation region at high rotation and high load other than these, the tumble on / off valve 12 is closed to at least a half-open state so that the in-cylinder gas flow is weakly tumble.
[0027]
Here, FIG. 8 is a schematic diagram showing the behavior of fuel by swirl during stratified combustion .
As shown in FIG. 8, at the time of cold start in stratified combustion, the swirl on-off valve 11 is closed to generate swirl in the combustion chamber 4, particularly in the recess 16 on the crown surface of the piston 3. By injecting fuel from the fuel injection valve 10, the fuel whose vaporization is promoted at the crown surface of the piston 3 can be transported to the spark plug 5 by the action of the swirl flow formed in the recess 16 without smoldering. Stratified combustion is possible.
[0028]
FIG. 9 is a schematic diagram showing the behavior of fuel by tumble during stratified combustion .
During stratified combustion (compression stroke injection), the tumble on-off valve 12 is closed to make the in-cylinder gas flow strong tumble. The fuel injected from the fuel injection valve 10 in the compression stroke is deflected to the upper side of the combustion chamber 4 by the tumble heading toward the upper side of the combustion chamber 4 after being reversed by the crown surface of the piston 3 and spreads to the spark plug 5 while spreading. Reached and ignited. Therefore, since the fuel does not pass through the crown surface of the piston 3, a liquid film is hardly formed, and smoke, HC generation, and deposit accumulation can be suppressed.
[0029]
However, at the time of cold start, it is switched to strong tumble after completion of warm-up as swirl flow. As a result, the mixing distribution at the time of starting the engine is improved, and stratified combustion is possible without causing the spark plug 5 to smolder.
In this embodiment, since the flow form can be changed by changing the notch shape, it can be easily deployed to other engines, and the flow strength can be easily adjusted by controlling the opening degree. Can be controlled.
[0030]
FIG. 10 is a longitudinal sectional view of an engine showing a second embodiment of the present invention, and FIG. 11 is a plan view of the piston in this case.
In the second embodiment , a concave portion (cylindrical combustion chamber) 17 having a cylindrical surface having a center line in the longitudinal direction of the engine is provided on the crown surface of the piston 3. Others are the same as the first embodiment.
[0031]
Thereby, since the tumble formed in the cylinder can be efficiently stored until the latter half of the compression stroke , the fuel can be deflected upward by the tumble and transported to the spark plug 5 and stable stratified combustion becomes possible.
FIG. 12 is a longitudinal sectional view of an engine showing a third embodiment of the present invention.
In the third embodiment , a circular shallow bowl-shaped combustion chamber 18 having a wall 18a that is eccentric on the intake valve 6A, 6B side and rises under the spark plug 5 is formed on the crown surface of the piston 3. A cylindrical combustion chamber formed with a cylindrical surface having a longitudinal center line substantially parallel to a line connecting the centers of the two intake valves 6A and 6B from the bottom of the spark plug 5 to the exhaust valves 7A and 7B. 19 is formed. Others are the same as the first embodiment.
[0032]
Thus, by forming the ball-type combustion chamber 18 for storing swirl and the cylindrical-type combustion chamber 19 for storing tumble on the crown surface of the piston 3, good performance can be exhibited in all areas of engine operation. Is possible.
FIG. 13 is a schematic plan view and longitudinal sectional view of an engine showing a fourth embodiment of the present invention.
In the fourth embodiment , a first on-off valve 21 is provided in the intake passage 8 for each cylinder. Also, two symmetrical left and right subports 22A and 22B are provided that branch from the upstream side of the first on-off valve 21 to the upper side and merge downstream of the first on-off valve 21 (immediately upstream of the intake valves 6A and 6B). And the 2nd on-off valve 23 is provided in the middle of one subport 22B. These correspond to swirl strengthening means and tumble strengthening means.
[0033]
In this case, the swirl can be generated by introducing the intake air asymmetrically only from the subport 22A by closing the second on-off valve 23 with the first on-off valve 21 closed.
In addition, by opening the second on-off valve 23 with the first on-off valve 21 closed, intake air is introduced symmetrically from both subports 22A and 22B, and the flow of the intake air is increased and decreased by the subports 22A and 22B. By biasing in the direction, a tumble can be generated.
[0034]
Thereby, a stronger gas flow can be generated in the cylinder, fuel can be deflected upward by tumble and transported to the spark plug 5, and more stable stratified combustion is possible.
In the fourth embodiment , a recess (ball-type combustion chamber) 16 similar to that of the first embodiment is provided on the crown of the piston 3, but a recess 17 (cylindrical combustion chamber) similar to the second embodiment is provided. ) Or a ball type combustion chamber 18 and a cylindrical type combustion chamber 19 as in the third embodiment .
[Brief description of the drawings]
FIG. 1 is a schematic plan view and longitudinal sectional view of an engine showing a first embodiment of the present invention.
Fig. 2 Top view of the piston
FIG. 3 is a view showing notch shapes of a swirl on-off valve and a tumble on-off valve.
FIG. 4 is a schematic diagram of a control system.
FIG. 5 is a diagram showing a control map
FIG. 6 is a diagram showing a control map
FIG. 7 is a diagram showing a control map . FIG. 8 is a schematic diagram showing fuel behavior by swirl during stratified combustion.
FIG. 9 is a schematic diagram showing the behavior of fuel by tumble during stratified combustion.
Longitudinal sectional view of the engine showing a second embodiment of the invention; FIG
[Fig. 11 ] Top view of the piston
Longitudinal sectional view of the engine showing a third embodiment of the present invention; FIG
Schematic plan view and a longitudinal sectional view of the engine showing a fourth embodiment of Figure 13 the present invention Description of Reference Numerals]
1 Cylinder head
2 Cylinder block
3 Piston
4 Combustion chamber
5 Spark plug
6A, 6B Intake valve
7A, 7B Exhaust valve
8 Intake passage
9 Exhaust passage
10 Fuel injection valve
11 On / off valve for swirl
11a Notch
12 Tumble open / close valve
12a Notch
13 Actuator
14 Actuator
15 Control unit (combustion control means and gas flow control means)
16 Concave (ball-type combustion chamber)
17 Concave (cylindrical combustion chamber)
18-ball type combustion chamber
19 Cylindrical combustion chamber
21 First on-off valve
22A, 22B Subport
23 Second on-off valve

Claims (8)

燃料噴射弁から燃焼室内に直接燃料を噴射し、点火栓により点火する直噴火花点火式内燃機関において、
吸入空気の流れを左右方向に偏らせて燃焼室内にスワールを生成することができるスワール強化手段と、
吸入空気の流れを上下方向に偏らせて燃焼室内にタンブルを生成することができるタンブル強化手段と、
前記スワール強化手段の作動と前記タンブル強化手段の作動とを制御するガス流動制御手段と、
機関の運転条件が所定の成層燃焼運転領域内にあるときに前記燃料噴射弁からの燃料噴射を圧縮行程に行う成層燃焼と、機関の運転条件が所定の均質燃焼運転領域内にあるときに前記燃料噴射弁からの燃料噴射を吸気行程に行う均質燃焼とを制御する燃焼制御手段と、
スワール強化時に混合気を形成する凹部を冠面に形成したピストンと、
を備え、
前記ガス流動制御手段は、前記成層燃焼が行われるときであって、かつ、所定のアイドル運転または機関の運転条件が所定の低回転低負荷領域内であるとき、および、前記均質燃焼が行われるときであって、かつ、比較的低回転領域であるときに、前記スワール強化手段を作動させる一方、前記成層燃焼が行われるときであって、かつ、所定のアイドル運転または機関の運転条件が所定の低回転負荷領域内でないとき、および、前記均質燃焼が行われるときであって、かつ、比較的低回転領域でないときに、前記タンブル強化手段を作動させることを特徴とする直噴火花点火式内燃機関。In a direct-injection spark-ignition internal combustion engine in which fuel is directly injected into a combustion chamber from a fuel injection valve and ignited by a spark plug,
Swirl strengthening means capable of generating a swirl in the combustion chamber by biasing the flow of intake air in the left-right direction;
Tumble strengthening means capable of generating tumble in the combustion chamber by biasing the flow of intake air in the vertical direction;
Gas flow control means for controlling the operation of the swirl strengthening means and the operation of the tumble strengthening means;
Stratified combustion in which fuel injection from the fuel injection valve is performed in a compression stroke when the engine operating condition is within a predetermined stratified combustion operation region, and when the engine operating condition is within a predetermined homogeneous combustion operation region Combustion control means for controlling homogeneous combustion in which fuel injection from the fuel injection valve is performed in the intake stroke;
A piston formed with a concave portion on the crown surface that forms an air-fuel mixture during swirl strengthening,
With
The gas flow control means performs the homogeneous combustion when the stratified combustion is performed and when the predetermined idle operation or the engine operating condition is within a predetermined low rotation and low load region. The swirl strengthening means is operated when the engine is in a relatively low rotation region, and the stratified combustion is performed and the predetermined idle operation or the engine operating condition is predetermined. The direct- injection spark ignition type is characterized in that the tumble strengthening means is operated when it is not within the low-rotation load region and when the homogeneous combustion is performed and is not in the relatively low-rotation region. Internal combustion engine. 前記スワール強化手段は、各気筒毎の吸気通路に設けられて、閉弁時に吸気通路断面の一部のみを連通させる左右非対称な切欠きを有するスワール用開閉弁であり、前記タンブル強化手段は、各気筒毎の吸気通路に設けられて、閉弁時に吸気通路断面の一部のみを連通させる左右対称な切欠きを有するタンブル用開閉弁であることを特徴とする請求項１記載の直噴火花点火式内燃機関。  The swirl strengthening means is a swirl opening / closing valve that is provided in the intake passage for each cylinder and has a left-right asymmetric cutout that communicates only a part of the cross section of the intake passage when the valve is closed. 2. A direct-injection spark according to claim 1, which is a tumble opening / closing valve provided in an intake passage for each cylinder and having a symmetrical notch that allows only a part of the cross-section of the intake passage to communicate when the valve is closed. Ignition internal combustion engine. 前記スワール強化手段及び前記タンブル強化手段は、各気筒毎の吸気通路に設けられた第１開閉弁と、この第１開閉弁上流から分岐して第１開閉弁下流に合流する左右対称な２本のサブポートと、一方のサブポートに設けられた第２開閉弁とを含んで構成されることを特徴とする請求項１記載の直噴火花点火式内燃機関。  The swirl strengthening means and the tumble strengthening means include a first on-off valve provided in the intake passage for each cylinder, and two bilaterally symmetrical branches that branch from the upstream side of the first on-off valve and merge downstream of the first on-off valve. The direct-injection spark-ignition internal combustion engine according to claim 1, further comprising: a sub-port of the first and second sub-ports provided in one of the sub-ports. 燃料噴射弁の噴射方向を吸気弁下方位置から燃焼室内にガス流動がない状態で点火栓を直撃しない方向に設定したことを特徴とする請求項１〜請求項３のいずれか１つに記載の直噴火花点火式内燃機関。  The injection direction of the fuel injection valve is set to a direction in which the ignition plug is not directly struck in a state where there is no gas flow from the lower position of the intake valve to the combustion chamber. Direct-injection spark ignition internal combustion engine. 前記ピストン冠面に形成した凹部は、機関前後方向に中心線を持つ円筒面からなることを特徴とする請求項１〜請求項４のいずれか１つに記載の直噴火花点火式内燃機関。The direct injection spark ignition internal combustion engine according to any one of claims 1 to 4, wherein the concave portion formed in the piston crown surface is formed of a cylindrical surface having a center line in the longitudinal direction of the engine. ピストン冠面上に、吸気弁側に偏心し、略点火栓下にて立上がる壁を有する円形状のボール型燃焼室を形成すると共に、略点火栓下から排気弁側にかけて２つの吸気弁の中心を結ぶ線と略平行に長手方向中心線を持つ円筒面にて形成された円筒型燃焼室を形成したことを特徴とする請求項１〜請求項４のいずれか１つに記載の直噴火花点火式内燃機関。  A circular ball-shaped combustion chamber having a wall that is eccentric to the intake valve side and rises substantially under the spark plug is formed on the piston crown surface, and two intake valves are formed from the bottom of the spark plug to the exhaust valve side. The direct eruption according to any one of claims 1 to 4, wherein a cylindrical combustion chamber formed by a cylindrical surface having a longitudinal center line substantially parallel to a line connecting the centers is formed. Flower ignition internal combustion engine. 前記ガス流動制御手段は、前記燃焼制御手段により成層燃焼が行われるときであって、かつ、所定のアイドル運転が行われるときに前記スワール強化手段を作動させ、前記燃焼制御手段により成層燃焼が行われるときであって、かつ、所定のアイドル運転が行われないときに前記タンブル強化手段を作動させることを特徴とする請求項１〜請求項６のいずれか１つに記載の直噴火花点火式内燃機関。 The gas flow control means activates the swirl strengthening means when stratified combustion is performed by the combustion control means and when a predetermined idle operation is performed, and stratified combustion is performed by the combustion control means. The direct-injection spark ignition type according to any one of claims 1 to 6 , wherein the tumble strengthening means is operated when a predetermined idle operation is not performed. Internal combustion engine. 前記ガス流動制御手段は、前記燃焼制御手段により成層燃焼が行われるときであって、かつ、機関の暖機が完了していないときに、強制的に前記スワール強化手段を作動させることを特徴とする請求項１〜請求項７のいずれか１つに記載の直噴火花点火式内燃機関。The gas flow control means forcibly operates the swirl strengthening means when stratified combustion is performed by the combustion control means and the engine is not warmed up. The direct-injection spark-ignition internal combustion engine according to any one of claims 1 to 7 .
JP20187698A 1998-01-06 1998-07-16 Direct-injection spark ignition internal combustion engine Expired - Lifetime JP3726503B2 (en)

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