JP3867319B2 - In-cylinder direct injection internal combustion engine - Google Patents

In-cylinder direct injection internal combustion engine Download PDF

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JP3867319B2
JP3867319B2 JP14467596A JP14467596A JP3867319B2 JP 3867319 B2 JP3867319 B2 JP 3867319B2 JP 14467596 A JP14467596 A JP 14467596A JP 14467596 A JP14467596 A JP 14467596A JP 3867319 B2 JP3867319 B2 JP 3867319B2
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combustion chamber
fuel
cylinder
spark plug
internal combustion
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JPH09324634A (en
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雅司 的場
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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
    • 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
    • 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
    • F02B23/101—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 or close to the cylinder centre axis, e.g. with mixture formation using spray guided concepts
    • 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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  • Combustion Methods Of Internal-Combustion Engines (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、筒内に燃料噴射弁により燃料を直接噴射し、点火プラグによって火花点火を行う筒内直噴式内燃機関に関し、詳しくは、燃料噴射弁と点火プラグの配置改善による燃焼性向上技術に関する。
【０００２】
【従来の技術】
従来、この種の筒内直噴式内燃機関の構造としては、図６に示すようなものがある（特開昭６２−８２２２２号公報参照）。
即ち、このものは、シリンダヘッド３０の幅方向の中央部に単一のカムシャフト３１を配置し、このカムシャフト３１によりスイングアーム３２を介して各気筒毎に設けられた２つの吸気バルブ３３と２つの排気バルブ３４とを駆動する機関であり、点火プラグ３５を、各排気バルブ３４間を通って、その先端の電極３５ａが燃焼室３６の中央部付近に臨むように設ける一方、燃料噴射弁３７を、各吸気バルブ３３間を通り、かつその先端噴孔３７ａが点火プラグ３５の先端の電極３５ａと対向して燃焼室３６の中央部付近に臨むように設けた構成となっている。
【０００３】
【発明が解決しようとする課題】
しかしながら、このような従来の筒内直噴式内燃機関にあっては、上述したように、点火プラグ３５の電極３５ａが燃焼室３６の中央部付近に臨み、燃料噴射弁３７の噴孔３７ａが前記電極３５ａと対向して燃焼室３６の中央部付近に臨んでいる構成であるため、次のような問題点がある。
【０００４】
即ち、燃焼室３６内のガス流動によって燃料噴射弁３７からの燃料噴霧が排気側に流されることと、燃料噴射弁３７の噴孔３７ａと点火プラグ３５の電極３５ａとの距離が、燃料噴霧のペネトレーションと比較してかなり短いこととにより、十分に気化されていない燃料噴霧が点火プラグ３５の電極３５ａに到達してしまい、該電極３５ａに液滴燃料が付着することによって、くすぶり等が生じる等、燃焼性能の悪化を来し、燃焼が不安定となり易くなると共に、機関出力の低下を来す虞があった。
【０００５】
そこで、本発明は以上のような従来の問題点に鑑み、筒内直噴式内燃機関における燃料噴射弁と点火プラグの配置の改善により、燃焼性能の向上、燃焼の安定性向上、機関出力の向上を図ることを課題とする。
【０００６】
【課題を解決するための手段】
このため、請求項１に係る発明は、ピストン冠面とシリンダボア内周面とシリンダヘッド下面との間に形成された燃焼室内に燃料を直接噴射する燃料噴射弁と、該燃料噴射弁から噴射された燃料の混合気に点火する点火プラグとを含んで構成され、筒内に流入した吸気がピストンの上昇に伴い、シリンダ中心軸を基準とする吸気側から排気側へ向かう順タンブル流を形成する吸気ポートの形状とされた筒内直噴式内燃機関において、前記点火プラグを、該点火プラグ先端の電極が各気筒毎に２つ設けられた排気バルブ間の燃焼室周縁部において該燃焼室内に露出するように、燃焼室壁に配設し、前記燃料噴射弁を、その先端噴孔が前記順タンブル流を形成する吸気の流れに関して前記点火プラグの電極の上流側で燃焼室内に露出し、かつ燃料の噴射方向が前記ピストン冠面に向くように、燃焼室壁に配設した。
【０００７】
かかる請求項１に係る発明において、早期噴射時、燃料噴射弁によって燃焼室内に噴射された燃料、即ち、燃料噴霧は、直接点火プラグの電極には向かわず、ピストンの冠面に向かって進行し、ピストンの冠面で受けられる。
又、燃焼室内に導入された吸気は、順タンブル流となる。
ここで、燃料噴霧のうちの液滴燃料は、ペネトレーションが強いため、ピストンの冠面まで到達して、該冠面で受け止められると共に、順タンブル流の作用により、ピストン冠面に沿って点火プラグの電極方向へ進行するのが妨げられ、更に、排気バルブは比較的高温であるため、燃料の気化が更に促進される。
【０００８】
これらの理由によって、液滴燃料が点火プラグの電極に到達するのが極力抑制される。
一方、燃料噴霧のうち、粒径が小さく噴射後に速やかに気化した気化燃料は、燃焼室内の順タンブル流により流されて点火プラグの電極に到達し、ピストン冠面の熱により気化した気化燃料も順タンブル流によって点火プラグの電極まで到達する。
【０００９】
ここで、燃焼室内に保持される順タンブル流によって噴射された直後の燃料噴霧は排気側に流される傾向にあり、かつシリンダボアはシリンダ中心軸と直交する断面において通常略真円であるため、排気バルブ間の燃焼室周縁部に比較的燃料噴霧が集まり易く、かかる排気バルブ間の燃焼室周縁部において点火プラグ先端の電極を燃焼室内に露出させるようにした結果、全ての条件において、燃焼安定性の向上を図ることができる。
【００１０】
請求項２に係る発明は、前記燃料噴射弁を、その先端噴孔が燃焼室に対応するシリンダヘッド下面の略中央部において該燃焼室内に露出し、かつ燃料噴霧の中心線がシリンダ中心軸に略平行となるように、燃焼室壁に配設した。
かかる構成においては、燃料噴射弁から噴射された燃料が排気バルブ間の燃焼室周縁部に配設された点火プラグの電極へ集中し易くなる。
【００１１】
請求項３に係る発明は、
前記燃料噴射弁を、その先端噴孔が燃焼室に対応するシリンダヘッド下面の略中央部において該燃焼室内に露出し、かつ燃料噴霧の中心線が噴孔部分を中心としてシリンダ中心軸位置から排気側に傾動した位置となるように、燃焼室壁に配設した。
【００１２】
かかる構成においては、燃料噴射弁から噴射された燃料が排気バルブ間の燃焼室周縁部に配設された点火プラグの電極へより集中し易くなる。
請求項４に係る発明は、前記燃料噴射弁を、その先端噴孔が各気筒毎に２つ設けられた吸気バルブ間の燃焼室周縁部において該燃焼室内に露出し、かつ燃料噴霧が噴孔部分と点火プラグ先端の電極とを結ぶ線よりも下側の領域に形成されるように、燃焼室壁に配設した。
【００１３】
かかる構成においては、燃料噴射弁と点火プラグとの距離が長く、燃料噴霧が噴孔部分と点火プラグの電極とを結ぶ線よりも下側の領域に形成されるため、燃料の点火プラグの電極への到達時間を長くすることができる。
請求項５に係る発明は、
前記ピストン冠面の排気側に内面が凹曲面の凹所を形成すると共に、この凹所から吸気側に***してシリンダヘッド下面に近接する***部を形成した。
【００１４】
かかる構成においては、ピストンの上死点付近での燃焼室は主として排気側に形成され、混合気温度が比較的高いことに伴い燃焼速度が速くなり、機関出力の向上を図ることができ、又、上死点付近にて吸気側でのスキッシュ流が生じ易く、順タンブル流の発生を更に助長させることができる。
請求項６に係る発明は、燃焼室内に燃料を直接噴射する筒内直噴式内燃機関であって、燃焼室内において、シリンダ中心軸を基準とする吸気側から排気側へ向かう吸気の順タンブル流が形成され、各気筒毎に２つ設けられた排気バルブ間の燃焼室周縁部に点火プラグを設置するとともに、前記順タンブル流を形成する吸気の流れに関して前記点火プラグの電極の上流側で、燃料噴射弁によりピストン冠面に向けて燃料を噴射して、前記点火プラグに対し、噴射された燃料のうち、液滴燃料が前記点火プラグの電極に到達するのが妨げられると共に、気化燃料が前記順タンブル流によって前記点火プラグの電極付近に集められるようにした。
【００１５】
【発明の効果】
請求項１及び６に係る発明によれば、
燃焼性能の向上を図ることができ、燃焼安定性が向上すると共に、機関出力の向上を図ることができる。
請求項２に係る発明によれば、
燃焼安定性の向上をより図ることができる。
【００１６】
請求項３に係る発明によれば、
燃焼安定性の向上を更により図ることができる。
請求項４に係る発明によれば、
順タンブル流によってより多くの気化燃料を点火プラグの電極に供給することができ、又、排気ポートの設計自由度を大きくとることができる。
【００１７】
請求項５に係る発明によれば、
機関出力の向上、燃焼安定性の向上という効果が更に大きくなる。
【００１８】
【発明の実施の形態】
以下、添付された図面を参照して本発明を詳述する。
図１，図２及び図３は、本発明の筒内直噴式内燃機関の一実施形態を示すシリンダ部分の断面図及び平面図であり、ピストン１２の冠面とシリンダボア９ｂ内周面とシリンダヘッド１下面との間には燃焼室８が形成され、この燃焼室８の上部のシリンダヘッド１壁、即ち、シリンダヘッド１下部に形成されたシリンダヘッド燃焼室８Ａの壁には並列する２つの吸気ポート４と並列する２つの排気ポート５とが設けられ、各吸気ポート４には吸気バルブ２が、各排気ポート５には排気バルブ３が、夫々配設され、各吸気ポート４及び各排気ポート５には、夫々吸気マニホールド１９及び排気マニホールド２０が接続される。
【００１９】
ここで、点火プラグ６は、該点火プラグ６先端の電極７が２つの排気バルブ３間の燃焼室８周縁部において該燃焼室８内に露出するように、燃焼室８のピストン１２の冠面と対向するシリンダヘッド１壁、即ち、シリンダヘッド燃焼室８Ａの壁に配設される。この場合、点火プラグ６は、シリンダ中心軸９ａに対して所定の角度をなすように配設される。
【００２０】
一方、燃料噴射弁１０は、その先端噴孔１０ａが燃焼室８に対応するシリンダヘッド１下面の略中央部において該燃焼室８内に露出し、かつ燃料噴霧１１の中心線１１ａがシリンダ中心軸９ａに略平行となるように、シリンダヘッド燃焼室８Ａの壁に配設される。
更に、ピストン１２の冠面は、燃料噴射弁１０から排気側に噴射された燃料の噴霧を受けて、該燃料噴霧が排気バルブ３間に配設された点火プラグ６の電極７方向に向かわしめる形状に形成される。
【００２１】
具体的には、ピストン１２の冠面の排気側に内面が凹曲面の凹所１３が形成され、この凹所１３から吸気側に***してシリンダヘッド１下面に近接する***部１４が形成される。
又、吸気ポート４は、該吸気ポート４からの吸気が燃焼室８内において順タンブル流１５となるような形状、例えば、下向きに若干湾曲して燃焼室８に連通される形状に形成される。
【００２２】
次に、かかる構成の作用について説明する。
図２及び図３において、早期噴射時、燃料噴射弁１０によって燃焼室８内に噴射された燃料、即ち、燃料噴霧１１は、直接点火プラグ６の電極７には向かわず、ピストン１２の冠面に向かって進行し、ピストン１２の冠面に形成された凹所１３で受けられる。
【００２３】
又、吸気ポート４から燃焼室８内に導入された吸気は、吸気ポート４の形状による作用で、図２及び図３の矢印で示す順タンブル流１５となる。
ここで、図１において、
（１）燃料噴霧１１のうちの液滴燃料１６は、ペネトレーションが強いため、ピストン１２の冠面まで到達して、凹所１３で受け止められる。
（２）液滴燃料１７は、順タンブル流１５の作用により、凹所１３内底面に沿って点火プラグ６の電極７方向へ進行するのが妨げられる。
（３）凹所１３は、排気側に位置しており、実質的な燃焼室８を構成する凹所１３並びに排気バルブ３は共に比較的高温であるため、燃料の気化が更に促進される。
【００２４】
等の理由によって、液滴燃料１７が点火プラグ６の電極７に到達するのが極力抑制される。
これにより、十分に気化されていない燃料噴霧が点火プラグ６の電極７に到達して、該電極７に液滴燃料が付着することによるくすぶり等の発生を抑制でき、燃焼性能の向上を図ることができる。
【００２５】
一方、燃料噴霧のうち、粒径が小さく噴射後に速やかに気化した気化燃料１７は、燃焼室８内の順タンブル流１５により流されて点火プラグ６の電極７に到達し、又、ピストン１２冠面に形成された凹所１３によって、圧縮行程においても順タンブル流１５をピストン１２の上死点付近において保持できるため、ピストン１２冠面の熱により気化した気化燃料１７も順タンブル流１５によって点火プラグ６の電極７まで到達し、これらにより、燃焼安定性が向上する。
【００２６】
ここで、実際には、燃料噴射期間は、機関運転条件によって変化させるようにしているため、この全ての条件で全ての燃料噴霧を凹所１３に受けることはできないが、燃焼室８内に保持される順タンブル流１５によって噴射された直後の燃料噴霧１１は排気側に流される傾向にあり、かつシリンダボア９ｂはシリンダ中心軸と直交する断面において通常略真円であるため、排気バルブ３間の燃焼室８周縁部に比較的燃料噴霧１１が集まり易く、かかる排気バルブ３間の燃焼室８周縁部において点火プラグ６先端の電極７を燃焼室８内に露出させるようにした結果、燃料噴霧１１を凹所１３に受けることはできない条件においても、燃焼安定性の向上を図ることができる。
【００２７】
又、上記の構成によると、ピストン１２冠面には、排気側に形成された凹所１３から吸気側に***してシリンダヘッド１下面に近接する***部１４を形成するようにしたから、上死点付近にて吸気側でのスキッシュ流が生じ易く、順タンブル流１５の発生を更に助長させることができ、前述した順タンブル流１５による効果、即ち、気化燃料が順タンブル流１５によって点火プラグ６の電極７まで到達して、燃焼安定性が向上するという効果が更に大きくなる。
【００２８】
更に、ピストン１２冠面の排気側に内面が凹曲面の凹所１３が形成されているため、ピストン１２の上死点付近での燃焼室８は主として排気側に形成され、混合気温度が比較的高いことに伴い燃焼速度が速くなり、機関出力の向上を図ることができる。
図４は、本発明の筒内直噴式内燃機関の他の実施形態を示すシリンダ部分の断面図であり、この実施形態においては、燃料噴射弁１０を、その先端噴孔１０ａが燃焼室８に対応するシリンダヘッド１下面の略中央部において該燃焼室８内に露出し、かつ燃料噴霧１１の中心線１１ａが噴孔１０ａ部分を中心としてシリンダ中心軸９ａ位置から排気側に傾動した位置となるように、シリンダヘッド燃焼室８Ａの壁に配設するようにしている。
【００２９】
かかる構成によれば、燃料噴射弁１０から噴射された燃料が排気バルブ３間の燃焼室８周縁部に配設された点火プラグ６の電極７へより集中し易くなり、燃焼安定性の向上をより図ることができる。
図５は、本発明の筒内直噴式内燃機関の更に他の実施形態を示すシリンダ部分の断面図であり、この実施形態においては、燃料噴射弁１０を、その先端噴孔１０ａが各気筒毎に２つ設けられた吸気バルブ２間の燃焼室８周縁部において該燃焼室８内に露出し、かつ燃料噴霧が噴孔１０ａ部分と点火プラグ６先端の電極７とを結ぶ線２３よりも下側の領域に形成されるように、シリンダヘッド燃焼室８Ａの壁に配設するようにしている。
【００３０】
かかる構成によれば、燃料噴射弁１０と点火プラグ６との距離が長く、燃料噴霧１１が噴孔１０ａ部分と点火プラグ６の電極７とを結ぶ線２３よりも下側の領域に形成されるため、燃料の点火プラグ６の電極７への到達時間を長くすることができ、この長い時間にて順タンブル流１５によってより多くの気化燃料１７を点火プラグ６の電極７に供給することができる。
【００３１】
尚、上述した全ての実施形態においては、夫々点火プラグ６を２つ設けられた排気バルブ３間の位置に配設するようにしているため、点火プラグ６の組み付け性の悪化を来す虞はない。
又、図５の実施形態においては、燃料噴射弁１０を排気ポート５から離れた吸気バルブ２側の位置に配設しているため、排気ポート５の設計自由度を大きくとることができる。
【図面の簡単な説明】
【図１】 本発明の筒内直噴式内燃機関の一実施形態を示すシリンダ部分の断面図
【図２】 本発明の筒内直噴式内燃機関の一実施形態を示すシリンダ部分の断面図
【図３】 同上の平面図
【図４】 他の実施形態を示すシリンダ部分の断面図
【図５】 更に他の実施形態を示すシリンダ部分の断面図
【図６】 従来の筒内直噴式内燃機関のを示す断面図
【符号の説明】
１ シリンダヘッド
２ 吸気バルブ
３ 排気バルブ
４ 吸気ポート
５ 排気ポート
６ 点火プラグ
７ 電極
８ 燃焼室
９ｂ シリンダボア
１０ 燃料噴射弁
１０ａ 噴孔
１２ ピストン[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-cylinder direct injection internal combustion engine in which fuel is directly injected into a cylinder by a fuel injection valve and spark ignition is performed by an ignition plug. More specifically, the present invention relates to a technique for improving combustibility by improving the arrangement of the fuel injection valve and the ignition plug. .
[0002]
[Prior art]
Conventionally, as a structure of this type of in-cylinder direct injection internal combustion engine, there is a structure as shown in FIG. 6 (see Japanese Patent Application Laid-Open No. 62-82222).
That is, in this, a single camshaft 31 is arranged at the center in the width direction of the cylinder head 30, and the two intake valves 33 provided for each cylinder via the swing arm 32 by the camshaft 31 and It is an engine that drives two exhaust valves 34, and a spark plug 35 is provided so that the electrode 35 a at the tip of the spark plug 35 passes between the exhaust valves 34 and faces the central portion of the combustion chamber 36. 37 is provided such that it passes between the intake valves 33 and the tip injection hole 37a faces the electrode 35a at the tip of the spark plug 35 so as to face the vicinity of the center of the combustion chamber 36.
[0003]
[Problems to be solved by the invention]
However, in such a conventional in-cylinder direct injection internal combustion engine, as described above, the electrode 35a of the spark plug 35 faces the vicinity of the center of the combustion chamber 36, and the injection hole 37a of the fuel injection valve 37 is formed in the above-described manner. Since the structure faces the electrode 35a and faces the vicinity of the center of the combustion chamber 36, there are the following problems.
[0004]
That is, the fuel spray from the fuel injection valve 37 is caused to flow to the exhaust side by the gas flow in the combustion chamber 36, and the distance between the injection hole 37a of the fuel injection valve 37 and the electrode 35a of the spark plug 35 is determined by the fuel spray. The fuel spray that is not sufficiently vaporized reaches the electrode 35a of the spark plug 35 due to the fact that it is considerably shorter than the penetration, and smoldering or the like occurs due to the droplet fuel adhering to the electrode 35a. As a result, the combustion performance deteriorates, the combustion tends to become unstable, and the engine output may decrease.
[0005]
Accordingly, in view of the above-described conventional problems, the present invention improves combustion performance, combustion stability, and engine output by improving the arrangement of fuel injection valves and spark plugs in a direct injection type internal combustion engine. The problem is to plan.
[0006]
[Means for Solving the Problems]
For this reason, the invention according to claim 1 is directed to a fuel injection valve that directly injects fuel into a combustion chamber formed between a piston crown surface, a cylinder bore inner peripheral surface, and a cylinder head lower surface, and the fuel injection valve. And a spark plug for igniting the fuel mixture, and as the piston rises, the intake air flowing into the cylinder forms a forward tumble flow from the intake side to the exhaust side with respect to the cylinder center axis. In an in-cylinder direct injection internal combustion engine having the shape of an intake port, the spark plug is exposed in the combustion chamber at the periphery of the combustion chamber between exhaust valves provided with two electrodes at the tip of the spark plug for each cylinder. The fuel injection valve is exposed in the combustion chamber upstream of the spark plug electrode with respect to the flow of intake air whose tip nozzle hole forms the forward tumble flow; and fuel As the injection direction is directed to the piston crown surface, it is disposed in the combustion chamber wall.
[0007]
In the first aspect of the invention, at the time of early injection, the fuel injected into the combustion chamber by the fuel injection valve, that is, fuel spray, does not go directly to the electrode of the spark plug, but proceeds toward the crown surface of the piston. , Received at the crown of the piston.
The intake air introduced into the combustion chamber becomes a forward tumble flow.
Here, the droplet fuel of the fuel spray has a strong penetration, so that it reaches the crown surface of the piston and is received by the crown surface, and the spark plug along the piston crown surface by the action of the forward tumble flow. Further, since the exhaust valve is relatively hot, vaporization of the fuel is further promoted.
[0008]
For these reasons, the droplet fuel is prevented from reaching the spark plug electrode as much as possible.
On the other hand, of the fuel spray, the vaporized fuel having a small particle size and quickly vaporized after injection is flowed by the forward tumble flow in the combustion chamber and reaches the electrode of the spark plug, and the vaporized fuel vaporized by the heat of the piston crown surface is also It reaches the electrode of the spark plug by the forward tumble flow.
[0009]
Here, the fuel spray immediately after being injected by the forward tumble flow held in the combustion chamber tends to flow to the exhaust side, and the cylinder bore is generally substantially circular in a cross section perpendicular to the cylinder central axis. liable relatively fuel spray gathered into the combustion chamber periphery between the valve, such exhaust at the combustion chamber periphery between the valve result of the electrodes of the spark plug tip and to expose the combustion chamber, under all conditions, the combustion Stability can be improved.
[0010]
According to a second aspect of the present invention, the fuel injection valve is exposed in the combustion chamber at a substantially central portion of the bottom surface of the cylinder head corresponding to the combustion chamber, and the center line of the fuel spray is on the cylinder central axis. It arrange | positioned in the combustion chamber wall so that it might become substantially parallel.
In such a configuration, the fuel injected from the fuel injection valve is likely to concentrate on the electrode of the spark plug disposed in the peripheral portion of the combustion chamber between the exhaust valves.
[0011]
The invention according to claim 3
The fuel injection valve is exposed in the combustion chamber at a substantially central portion of the lower surface of the cylinder head corresponding to the combustion chamber, and the fuel spray center line is exhausted from the cylinder center axis position centering on the injection hole portion. It arrange | positioned in the combustion chamber wall so that it might become the position tilted to the side.
[0012]
In such a configuration, the fuel injected from the fuel injection valve is more likely to concentrate on the electrode of the spark plug disposed at the peripheral portion of the combustion chamber between the exhaust valves.
Invention, the fuel injection valve, the tip nozzle holes Te combustion chamber periphery smell between the intake valves provided two for each cylinder exposed to the combustion chamber, and fuel spray injection according to claim 4 It arrange | positioned in the combustion chamber wall so that it might form in the area | region below the line which connects a hole part and the electrode of a spark plug front-end | tip.
[0013]
In such a configuration, since the distance between the fuel injection valve and the spark plug is long and the fuel spray is formed in a region below the line connecting the nozzle hole portion and the spark plug electrode, the fuel spark plug electrode The time to reach can be increased.
The invention according to claim 5
A recess having a concave curved surface was formed on the exhaust side of the piston crown surface, and a raised portion was formed to protrude from the recess toward the intake side and close to the lower surface of the cylinder head.
[0014]
In such a configuration, the combustion chamber in the vicinity of the top dead center of the piston is mainly formed on the exhaust side, and the combustion speed increases with a relatively high air-fuel mixture temperature, and the engine output can be improved. The squish flow on the intake side is likely to occur near the top dead center, and the generation of the forward tumble flow can be further promoted.
The invention according to claim 6 is the in-cylinder direct-injection internal combustion engine that directly injects fuel into a combustion chamber, the combustion chamber, the order tumble flow of intake air flowing from the intake side relative to the cylinder center axis to the exhaust side A spark plug is installed at the periphery of the combustion chamber between the two exhaust valves formed for each cylinder , and the fuel flows upstream of the spark plug electrode with respect to the flow of intake air forming the forward tumble flow. and injecting fuel toward the piston crown surface by the injection valve, to said spark plug, of the injection Isa fuel, the droplet fuel is prevented from reaching the electrodes of the spark plug, the fuel gas There was to be collected in the vicinity of electrodes of the spark plug by said forward tumble flow.
[0015]
【The invention's effect】
According to the invention which concerns on Claim 1 and 6,
Combustion performance can be improved, combustion stability can be improved, and engine output can be improved.
According to the invention of claim 2,
The combustion stability can be further improved.
[0016]
According to the invention of claim 3,
The combustion stability can be further improved.
According to the invention of claim 4,
More vaporized fuel can be supplied to the electrode of the spark plug by the forward tumble flow, and the design freedom of the exhaust port can be increased.
[0017]
According to the invention of claim 5,
The effects of improving engine output and combustion stability are further increased.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
1, 2 and 3 are a sectional view and a plan view of a cylinder portion showing one embodiment of a direct injection type internal combustion engine of the present invention, a crown surface of a piston 12, an inner peripheral surface of a cylinder bore 9b, and a cylinder head. 1, a combustion chamber 8 is formed between the lower surface of the cylinder head 1 and two intakes arranged in parallel on the wall of the cylinder head 1 above the combustion chamber 8, that is, on the wall of the cylinder head combustion chamber 8 A formed at the bottom of the cylinder head 1. Two exhaust ports 5 in parallel with the ports 4 are provided, each intake port 4 is provided with an intake valve 2, each exhaust port 5 is provided with an exhaust valve 3, and each intake port 4 and each exhaust port is provided. 5 are connected to an intake manifold 19 and an exhaust manifold 20, respectively.
[0019]
Here, the spark plug 6 so as to expose the ignition plug 6 the tip of the electrode 7 Te combustion chamber 8 periphery smell between the two exhaust valves 3 into the combustion chamber 8, the piston 12 of the combustion chamber 8 crown The cylinder head 1 wall facing the surface, that is, the wall of the cylinder head combustion chamber 8A is disposed. In this case, the spark plug 6 is disposed at a predetermined angle with respect to the cylinder center shaft 9a.
[0020]
On the other hand, the fuel injection valve 10 has a tip injection hole 10a exposed in the combustion chamber 8 at a substantially central portion of the lower surface of the cylinder head 1 corresponding to the combustion chamber 8, and a center line 11a of the fuel spray 11 is a cylinder central axis. It is disposed on the wall of the cylinder head combustion chamber 8A so as to be substantially parallel to 9a.
Further, the crown surface of the piston 12 receives the spray of fuel injected from the fuel injection valve 10 toward the exhaust side, and the fuel spray is directed toward the electrode 7 of the spark plug 6 disposed between the exhaust valves 3. It is formed into a shape.
[0021]
Specifically, a recess 13 having a concave curved inner surface is formed on the exhaust side of the crown surface of the piston 12, and a raised portion 14 that protrudes from the recess 13 toward the intake side and is close to the lower surface of the cylinder head 1 is formed. The
Further, the intake port 4 is formed in such a shape that intake air from the intake port 4 becomes a forward tumble flow 15 in the combustion chamber 8, for example, a shape that is slightly curved downward and communicated with the combustion chamber 8. .
[0022]
Next, the operation of this configuration will be described.
2 and 3, the fuel injected into the combustion chamber 8 by the fuel injection valve 10 at the time of early injection, that is, the fuel spray 11 does not go directly to the electrode 7 of the spark plug 6, but the crown surface of the piston 12. And is received by a recess 13 formed in the crown surface of the piston 12.
[0023]
The intake air introduced from the intake port 4 into the combustion chamber 8 becomes a forward tumble flow 15 indicated by the arrows in FIGS. 2 and 3 due to the action of the shape of the intake port 4.
Here, in FIG.
(1) The droplet fuel 16 in the fuel spray 11 has a strong penetration, so that it reaches the crown surface of the piston 12 and is received in the recess 13.
(2) The droplet fuel 17 is prevented from traveling toward the electrode 7 of the spark plug 6 along the inner bottom surface of the recess 13 by the action of the forward tumble flow 15.
(3) Since the recess 13 is located on the exhaust side, and the recess 13 and the exhaust valve 3 that substantially constitute the combustion chamber 8 are both relatively hot, vaporization of fuel is further promoted.
[0024]
For the reasons described above, the droplet fuel 17 is prevented from reaching the electrode 7 of the spark plug 6 as much as possible.
As a result, fuel spray that is not sufficiently vaporized reaches the electrode 7 of the spark plug 6 and the occurrence of smoldering or the like due to the droplet fuel adhering to the electrode 7 can be suppressed, thereby improving the combustion performance. Can do.
[0025]
On the other hand, of the fuel spray, the vaporized fuel 17 having a small particle size and rapidly vaporized after the injection is caused to flow by the forward tumble flow 15 in the combustion chamber 8 to reach the electrode 7 of the spark plug 6, and the crown of the piston 12 Since the forward tumble flow 15 can be held near the top dead center of the piston 12 even in the compression stroke by the recess 13 formed on the surface, the vaporized fuel 17 vaporized by the heat of the crown surface of the piston 12 is also ignited by the forward tumble flow 15. It reaches the electrode 7 of the plug 6, and these improve the combustion stability.
[0026]
Here, in practice, the fuel injection period is changed depending on the engine operating conditions, so that all fuel sprays cannot be received in the recess 13 under all these conditions, but are retained in the combustion chamber 8. the fuel spray 11 immediately after being injected by forward tumble flow 15 which is tend to flow to the exhaust side, and since the cylinder bore 9b is usually substantially round shape in a cross section perpendicular to the cylinder center axis, between the exhaust valve 3 liable relatively fuel spray 11 is gathered into the combustion chamber 8 the peripheral portion, as a result of the spark plug 6 the tip of the electrode 7 so as to expose the combustion chamber 8 at the combustion chamber 8 the periphery between such an exhaust valve 3, the fuel Even under conditions where the spray 11 cannot be received in the recess 13, the combustion stability can be improved.
[0027]
Further, according to the above configuration, the crown 12 of the piston 12 is formed with the raised portion 14 that protrudes from the recess 13 formed on the exhaust side toward the intake side and is close to the lower surface of the cylinder head 1. The squish flow on the intake side is likely to occur near the dead point, and the generation of the forward tumble flow 15 can be further promoted. The effect of the forward tumble flow 15, that is, the vaporized fuel is ignited by the forward tumble flow 15. 6 reaches the electrode 7 and the effect of improving the combustion stability is further increased.
[0028]
Further, since a recess 13 having a concave curved inner surface is formed on the exhaust side of the crown surface of the piston 12, the combustion chamber 8 near the top dead center of the piston 12 is mainly formed on the exhaust side, and the mixture temperature is compared. As the engine speed increases, the combustion speed increases and the engine output can be improved.
FIG. 4 is a cross-sectional view of a cylinder portion showing another embodiment of the direct injection type internal combustion engine of the present invention. In this embodiment, the fuel injection valve 10 has a tip injection hole 10 a at the combustion chamber 8. The center line 11a of the fuel spray 11 is exposed to the exhaust side from the position of the cylinder center axis 9a with the nozzle hole 10a as a center, and is exposed in the combustion chamber 8 at a substantially central portion of the corresponding lower surface of the cylinder head 1. Thus, it arrange | positions on the wall of the cylinder head combustion chamber 8A.
[0029]
According to such a configuration, the fuel injected from the fuel injection valve 10 is more likely to concentrate on the electrode 7 of the spark plug 6 disposed in the peripheral portion of the combustion chamber 8 between the exhaust valves 3, thereby improving the combustion stability. More can be planned.
FIG. 5 is a cross-sectional view of a cylinder portion showing still another embodiment of the direct injection type internal combustion engine of the present invention. In this embodiment, the fuel injection valve 10 has a tip injection hole 10a for each cylinder. the exposed combustion chamber 8 periphery smell between the two provided intake valve 2 Te into the combustion chamber 8, and also the line 23 to the fuel spray connecting the injection hole 10a portion and the spark plug 6 the tip of the electrode 7 It is arranged on the wall of the cylinder head combustion chamber 8A so as to be formed in the lower region.
[0030]
According to this configuration, the distance between the fuel injection valve 10 and the spark plug 6 is long, and the fuel spray 11 is formed in a region below the line 23 connecting the injection hole 10a portion and the electrode 7 of the spark plug 6. Therefore, the arrival time of the fuel to the electrode 7 of the spark plug 6 can be lengthened, and more vaporized fuel 17 can be supplied to the electrode 7 of the spark plug 6 by the forward tumble flow 15 in this long time. .
[0031]
In all of the above-described embodiments, the spark plug 6 is disposed at a position between the two exhaust valves 3 provided, so there is a risk that the assembling property of the spark plug 6 may be deteriorated. Absent.
In the embodiment of FIG. 5, since the fuel injection valve 10 is disposed at the position on the intake valve 2 side away from the exhaust port 5, the design freedom of the exhaust port 5 can be increased.
[Brief description of the drawings]
FIG. 1 is a sectional view of a cylinder portion showing an embodiment of a direct injection type internal combustion engine of the present invention. FIG. 2 is a sectional view of a cylinder portion showing an embodiment of the direct injection type internal combustion engine of the present invention. 3] Plan view of the same. [FIG. 4] Cross-sectional view of a cylinder portion showing another embodiment. [FIG. 5] Cross-sectional view of a cylinder portion showing still another embodiment. [FIG. Sectional view showing [signs]
DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Intake valve 3 Exhaust valve 4 Intake port 5 Exhaust port 6 Spark plug 7 Electrode 8 Combustion chamber 9b Cylinder bore 10 Fuel injection valve 10a Injection hole 12 Piston

Claims (6)

ピストン冠面とシリンダボア内周面とシリンダヘッド下面との間に形成された燃焼室内に燃料を直接噴射する燃料噴射弁と、該燃料噴射弁から噴射された燃料の混合気に点火する点火プラグとを含んで構成され、
筒内に流入した吸気がピストンの上昇に伴い、シリンダ中心軸を基準とする吸気側から排気側へ向かう順タンブル流を形成する吸気ポートの形状とされた筒内直噴式内燃機関において、
前記点火プラグを、該点火プラグ先端の電極が各気筒毎に２つ設けられた排気バルブ間の燃焼室周縁部において該燃焼室内に露出するように、燃焼室壁に配設し、
前記燃料噴射弁を、その先端噴孔が前記順タンブル流を形成する吸気の流れに関して前記点火プラグの電極の上流側で燃焼室内に露出し、かつ燃料の噴射方向が前記ピストン冠面に向くように、燃焼室壁に配設したことを特徴とする筒内直噴式内燃機関。A fuel injection valve that directly injects fuel into a combustion chamber formed between a piston crown surface, a cylinder bore inner peripheral surface, and a cylinder head lower surface; and an ignition plug that ignites a fuel mixture injected from the fuel injection valve; Comprising
In the in-cylinder direct injection internal combustion engine having the shape of an intake port that forms a forward tumble flow from the intake side toward the exhaust side with reference to the cylinder center axis as the piston that has flowed into the cylinder rises,
The spark plug is disposed on the combustion chamber wall so that the electrode at the tip of the spark plug is exposed in the combustion chamber at the periphery of the combustion chamber between two exhaust valves provided for each cylinder ,
The fuel injection valve is exposed in the combustion chamber on the upstream side of the spark plug electrode with respect to the intake air flow whose tip nozzle hole forms the forward tumble flow, and the fuel injection direction faces the piston crown surface. And an in-cylinder direct injection internal combustion engine characterized by being disposed on the combustion chamber wall . 前記燃料噴射弁は、その先端噴孔が燃焼室に対応するシリンダヘッド下面の略中央部において該燃焼室内に露出し、かつ燃料噴霧の中心線がシリンダ中心軸に略平行となるように、燃焼室壁に配設されたことを特徴とする請求項１記載の筒内直噴式内燃機関。  The fuel injection valve is combusted so that the tip nozzle hole is exposed in the combustion chamber at the substantially central portion of the cylinder head lower surface corresponding to the combustion chamber, and the center line of the fuel spray is substantially parallel to the cylinder central axis. 2. The direct injection type internal combustion engine according to claim 1, wherein the direct injection type internal combustion engine is disposed on a chamber wall. 前記燃料噴射弁は、その先端噴孔が燃焼室に対応するシリンダヘッド下面の略中央部において該燃焼室内に露出し、かつ燃料噴霧の中心線が噴孔部分を中心としてシリンダ中心軸位置から排気側に傾動した位置となるように、燃焼室壁に配設されたことを特徴とする請求項１記載の筒内直噴式内燃機関。  The fuel injection valve has an end nozzle hole exposed in the combustion chamber at a substantially central portion of the lower surface of the cylinder head corresponding to the combustion chamber, and a fuel spray center line exhausted from the cylinder center axis position centering on the nozzle hole portion. The in-cylinder direct injection internal combustion engine according to claim 1, wherein the direct-injection internal combustion engine is disposed on the combustion chamber wall so as to be inclined to the side. 前記燃料噴射弁は、その先端噴孔が各気筒毎に２つ設けられた吸気バルブ間の燃焼室周縁部において該燃焼室内に露出し、かつ燃料噴霧が噴孔部分と点火プラグ先端の電極とを結ぶ線よりも下側の領域に形成されるように、燃焼室壁に配設されたことを特徴とする請求項１記載の筒内直噴式内燃機関。  The fuel injection valve is exposed in the combustion chamber at the peripheral edge of the combustion chamber between the intake valves provided with two tip nozzle holes for each cylinder, and the fuel spray is formed at the nozzle hole portion and the electrode at the tip of the spark plug. 2. The direct injection type internal combustion engine according to claim 1, wherein the direct injection type internal combustion engine is disposed on the combustion chamber wall so as to be formed in a region below a line connecting the two. 前記ピストン冠面の排気側に内面が凹曲面の凹所を形成すると共に、この凹所から吸気側に***してシリンダヘッド下面に近接する***部を形成したことを特徴とする請求項１〜４のうちいずれか１つに記載の筒内直噴式内燃機関。  The inner surface of the piston crown surface is formed with a concave curved concave portion, and a raised portion is formed near the lower surface of the cylinder head. The in-cylinder direct injection internal combustion engine according to any one of 4. 燃焼室内に燃料を直接噴射する筒内直噴式内燃機関であって、
燃焼室内において、シリンダ中心軸を基準とする吸気側から排気側へ向かう吸気の順タンブル流が形成され、
各気筒毎に２つ設けられた排気バルブ間の燃焼室周縁部に点火プラグを設置するとともに、
前記順タンブル流を形成する吸気の流れに関して前記点火プラグの電極の上流側で、燃料噴射弁によりピストン冠面に向けて燃料を噴射して、前記点火プラグに対し、噴射された燃料のうち、液滴燃料が前記点火プラグの電極に到達するのが妨げられると共に、気化燃料が前記順タンブル流によって前記点火プラグの電極付近に集められるようにした筒内直噴式内燃機関。 A cylinder direct injection internal combustion engine that directly injects fuel into a combustion chamber,
In the combustion chamber, a forward tumble flow of intake air from the intake side toward the exhaust side with respect to the cylinder central axis is formed,
In addition to installing a spark plug at the periphery of the combustion chamber between two exhaust valves provided for each cylinder,
Upstream of the electrodes of the spark plug with respect to the flow of the intake air to form the forward tumble flow, and injecting fuel toward the piston crown surface by the fuel injection valve with respect to the spark plug, of the injection Isa fuel , the droplet fuel is prevented from reaching the electrodes of the spark plug, the fuel gas cylinder direct injection internal combustion engine which is adapted collected near electrodes of said spark plug by said forward tumble flow.
JP14467596A 1996-06-06 1996-06-06 In-cylinder direct injection internal combustion engine Expired - Lifetime JP3867319B2 (en)

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