JP3893750B2

JP3893750B2 - Direct cylinder injection spark ignition engine

Info

Publication number: JP3893750B2
Application number: JP16453198A
Authority: JP
Inventors: 祐一入矢; 久司光本
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1998-06-12
Filing date: 1998-06-12
Publication date: 2007-03-14
Anticipated expiration: 2018-06-12
Also published as: JPH11351012A

Description

【０００１】
【発明の属する技術分野】
この発明は、直接筒内噴射式火花点火機関に関する。
【０００２】
【従来の技術】
従来の直接筒内噴射式火花点火機関としては、例えば図１８から図２０（特開平５−７９３７０号公報）に示すようなものがある。これはピストン０１頂面に形成された凹状の燃焼室キャビティ０２と、ピストン０１の上昇に伴い点火時点において燃焼室キャビティ０２の側壁近傍に挿入される点火プラグ０４を設置し、吸気ポート０５はヘリカル型吸気ポートを形成する第１吸気ポート０５ａとまっすぐに伸びるストレート型吸気ポートを形成する第２吸気ポート０５ｂとからなる。また、これら各吸気ポート０５ａ，０５ｂは各々インテークマニホールド内に形成された吸気通路０１０を介してコレクタ０１１につながり、第２吸気ポート０５ｂにつながる第２吸気通路０１０ｂ内に吸気制御弁０１２を設置している。さらに、前記吸気ポート０５下部に、燃焼室０３に対し斜め下向きに高圧燃料噴射弁０６を設置している。そして、この従来例は、特定の運転状態のとき、吸気制御弁０１２の開閉制御０１３によりスワール流０９のガス流動を生成し、燃料の点火プラグ０４周りの成層化をし、超希薄空燃比で運転し燃費の向上を図るものである。なお、０７は吸気弁、０８は排気弁である。
【０００３】
【発明が解決しようとする課題】
しかしながら、このような従来の直接筒内噴射式火花点火機関にあっては、成層時に強いスワール流０９を形成する必要があるために、吸気制御弁０１２による第２吸気ポート０５ｂの閉鎖のみでは強いスワール流０９を形成することができないため、第１吸気ポート０５ａをヘリカル形状としている。
このため、高回転・高負荷時の出力域では吸気抵抗となり、出力性能が低下する。また、成層時にエバポ燃料をパージする場合に、従来のスワール流０９のガス流動を用いた成層燃焼ではパージガスは第１吸気ポート０５ａを介してスワール流０９のガス流動にのって燃焼室０３内に流入するため、エバポ燃料は燃焼室０３の外側に長く存在し、ピストン０１頂面上の燃焼室キャビティ０２内に集中しないため、この燃焼室キャビティ０２内での噴射燃料と混合した燃焼が困難となり、排気性能が悪化してしまう。
この発明は、このような従来の問題点に着目してなされたもので、成層燃焼時における良好なパージを行い得るとともに、高回転・高負荷時の出力を向上させることができる直接筒内噴射式火花点火機関を提供することにある。
【０００４】
【課題を解決するための手段】
上述の目的を達成するため、請求項１記載の発明は、１つの気筒に対して３つの吸気ポートを形成するとともに、３つの吸気ポートの中央に位置する中央第１吸気ポートを吸気の流れがピストンの凹部に直接向かう形状に形成し、中央第１吸気ポートの上壁に吸気の流れ方向に沿ったガイド溝を形成し、中央第１吸気ポートの上流側に遮断弁を設け、遮断弁下流側の中央第１吸気ポートのガイド溝近傍にエバポパージの流出口を設け、中央第１吸気ポートの両側に位置する第２吸気ポートおよび第３吸気ポートを吸気の流れが燃焼室内でタンブル流を生起する形状に形成し、第３吸気ポートを開閉する吸気弁の作動を運転状態に応じて停止する可変動弁機構と、機関の運転状態に応じて遮断弁の開閉を制御する遮断弁開閉機構と、機関の運転状態に応じて燃料の噴射時期を制御する噴射時期制御手段と、を備えることを特徴とする。
請求項１記載の直接筒内噴射式火花点火機関によれば、運転条件に応じた各ポートの開閉制御により、成層時の強いスワール流の形成と弱成層時の２つの順タンブルガス流動の形成、均質希薄燃焼時の弱いスワール流の形成、高回転・高負荷時の出力域での低吸気抵抗化の両立を図り、特定時期の燃料噴射により超希薄空燃比運転による燃費の向上とスロットル全開運転時の空気の充填効率増大化による出力性能向上の両立を図ることができる。また、成層時にエバポ燃料をパージする場合に、中央第１ポートから導入でき、かつ燃焼室内のガス流動を制御することが可能なため、パージガスをピストン頂面上の燃焼室内に集中でき、この燃焼室内で噴射燃料との混合を促進でき、燃焼が改善され、排気性能の悪化を防ぐことができる。
また、上記のようにガイド溝を設けることで、機関の運転条件が、低中速・低負荷域の成層燃焼領域、および低中速・中負荷域の弱成層燃焼領域でのエバポ燃料をパージする場合において、エバポ燃料は中央第１吸気ポートの上部を流れ、主に第１吸気弁の排気弁側開口部から直接ピストン頂面上の燃焼室に向けて大半が入り、スワールガス流動、あるいは２つの順タンブル流ガス流動の中央に位置するピストン頂面上の燃焼室内により多く集中するのでこの燃焼室内で噴射燃料との混合が促進され、安定燃焼が可能となる。
【０００５】
また、請求項２記載の発明は、請求項１記載の直接筒内噴射式火花点火機関において、機関の運転状態が点火栓近傍に混合気を集める成層燃焼を行う領域にあるとき、可変動弁機構は第３吸気ポートの吸気弁の作動を停止し、遮断弁開閉機構は中央第１吸気ポートの遮断弁を閉鎖し、噴射時期制御手段は燃料噴射時期を圧縮行程後期に設定する、ことを特徴とする。
請求項２記載の直接筒内噴射式火花点火機関によれば、機関の運転条件が、低中速・低負荷域の成層燃焼領域では、筒内のガス流動を強めると共に、強いスワール流を形成し、燃料を少なくとも圧縮行程後期に噴射することで、燃料の点火プラグ周りの成層化を図り、超希薄空燃比で運転し燃費の向上を図ることができると共に、燃料は一度ピストン表面の燃焼室を介して、点火プラグ方向へ行くため、燃料微粒化、および気化が進み、点火プラグへの液状燃料付着による失火は無く、安定して運転できるようになる。また、エバポ燃料をパージする場合でも、エバポ燃料は中央第１吸気ポートから直接ピストン頂面上の燃焼室に向けて入れるので、スワールガス流動の中央であるピストン頂面上の燃焼室内にパージガスは集中し、前記燃焼室内で噴射燃料と混合し安定燃焼が可能となる。
【０００６】
請求項３記載の発明では、請求項１または２記載の直接筒内噴射式火花点火機関において、機関の運転状態が点火栓近傍に混合気を集める弱成層燃料を行う領域にあるとき、可変動弁機構は第３吸気ポートの吸気弁を作動させ、遮断弁開閉機構は中央第１吸気ポートの遮断弁を閉鎖し、噴射時期制御手段は燃料噴射時期を圧縮行程前期に設定する、ことを特徴とする。
請求項３記載の直接筒内噴射式火花点火機関によれば、機関の運転条件が、低中速・中負荷域の成層燃焼領域では、筒内のガス流動を若干弱めるとともに、燃焼室に入ってくる吸入空気が２つの順タンブル流ガス流動を生成し、燃料を少なくとも圧縮行程前期に噴射することで、前記２つのタンブル流ガス流動の中間に燃料混合気の帯を生成する弱い成層化をし、希薄空燃比で運転し、燃費の向上を図ることができる。また、エバポ燃料をパージする場合も、２つの順タンブル流ガス流動の中央にパージガスは集中し、そのガス流動中間の燃料混合気の帯と混合し安定燃焼が可能となる。
【０００７】
請求項４記載の発明では、請求項１ないし３のいずれかの項に記載の直接筒内噴射式火花点火機関において、機関の運転状態が燃焼室内に均質な希薄混合気を形成する均質希薄燃焼を行う領域にあるとき、可変動弁機構は第３吸気ポートの吸気弁を停止させ、遮断弁開閉機構は中央第１吸気ポートの遮断弁を開き、噴射時期制御手段は燃料噴射時期を吸気行程に設定する、ことを特徴とする。
請求項４記載の直接筒内噴射式火花点火機関によれば、機関の運転条件が、低中速・中負荷域の均質希薄燃焼領域では、強いスワール流を、中央第１吸気ポートから流入する燃焼室に入ってくる吸入空気流れにより弱め、燃料を少なくとも吸気行程に噴射することで、燃料混合気の均質化を図り、希薄空燃比で運転し、燃費の向上を図ることができる。また、エバポ燃料をパージする場合は燃料噴射が吸気行程時のためパージガスと噴射燃料は十分混合し、従来の吸気ポート燃料噴射機関と同様に安定燃焼が可能となる。
【０００８】
請求項５記載の発明では、請求項１ないし４記載の直接筒内噴射式火花点火機関において、機関の運転状態が燃焼室内に均質な混合気を形成する均質燃焼を行う領域にあるとき、可変動弁機構は第３吸気ポートの吸気弁を作動させ、遮断弁開閉機構は中央第１ポートの遮断弁を開き、噴射時期制御手段は燃料噴射時期を吸気行程に設定する、ことを特徴とする。
請求項５記載の直接筒内噴射式火花点火機関によれば、機関の運転条件が、高速・高負荷域の均質燃焼領域では、吸気ポート面積を大きくし充填効率向上を図るとともに、燃料を少なくとも吸気行程時に噴射することで、混合気の均質化を図り、出力領域も十分な性能を確保できる。また、エバポ燃料をパージする場合は、燃料噴射が吸気行程時のためパージガスと噴射燃料は十分混合し、従来の吸気ポート燃料噴射機関と同様に安定燃焼が可能となる。
【０００９】
請求項６記載の発明では、請求項１ないし５記載の直接筒内噴射式火花点火機関において、中央第１吸気ポートはシリンダに対して直立してピストンの凹部を指向する形状であり、第２吸気ポートおよび第３吸気ポートは燃焼室内にタンブル流を生起するストレート形状である、ことを特徴とする。
請求項６記載の直接筒内噴射式火花点火機関によれば、中央第１吸気ポートから流入する流れはピストン頂面上の燃焼室内に向かい、第２、第３吸気ポートから流入する流れは順タンブルを形成するため、運転条件に応じた各ポートの開閉制御時に、運転条件に応じた要求ガス流動（成層時の強いスワール流の形成、弱成層時の２つの順タンブルガス流動の形成、均質希薄燃焼時の弱いスワール流の形成、高回転・高負荷時の出力域での低吸気抵抗化）を形成できる。
【００１２】
【発明の実施の形態】
以下、この発明の実施の形態を図面に基づいて説明する。
図１から図４は、本発明の実施の形態の直接筒内噴射式火花点火機関（以下、機関と称す）の構成を示す図である。
まず、構成を説明すると、本実施の形態の機関は、ピストン１頂面に形成された凹部を有する燃焼室キャビティ２と、シリンダ１７のシリンダヘッドに燃焼室キャビティ２を臨んで挿入される点火プラグ４と、吸気ポート５下部に、燃焼室３に対し斜め下向きに燃料を筒内に直接噴射する高圧燃料噴射弁６とを有する。そして、本実施の形態は、１つの気筒に対して３つの吸気弁７と吸気ポート５が形成されているが、３つの吸気弁７の中央に位置する第１吸気弁７ａにつながる第１吸気ポート５ａはその吸気ポートを介して流入する吸気流れが、図３（ａ）に示すように、ピストン１頂面上の燃焼室キャビティ２内に向かうような吸気ポート形状としている。そして、第１吸気ポート５ａ上流の第１吸気通路１０ａに遮断弁１２を設け、この遮断弁１２の下流にエバポパージ用流出口１４を設ける。また、第１吸気弁７ａの両側の２つの第２吸気弁７ｂおよび第３吸気弁７ｃにつながる第２吸気ポート５ｂおよび第３吸気ポート５ｃは、その吸気ポートを介して流入する吸気流れが、図５に示すように、燃焼室３内で順タンブルガス流動１９を形成するような吸気ポート形状としている。そして、前記第１吸気弁７ａ、第２吸気弁７ｂおよび第３吸気弁７ｃを機関の運転条件により各々開閉するような可変動弁機構１６と遮断弁開閉機構１３とを設ける。なお、８は排気弁、１０ｂは第２吸気ポート５ｂにつながる第２吸気通路、１０ｃは第３吸気ポート５ｃにつながる第３吸気通路であり、１１はコレクタ、１５はエバポパージ制御機構である。
さらに、図３（ｂ）には、図３（ａ）のＳ３ｂ−Ｓ３ｂ断面を示す。図３（ｂ）に示すように、ピストン１頂面上の燃焼室キャビティ２に向かう第１吸気ポート５ａの断面形状として、吸気ポート５ａ上部に吸入空気流れを誘導するガイド２０を設けている。
【００１３】
機関の運転状態そして負荷はアクセル開度センサ２２により検出され、回転数はクランク角センサ２１により検出され、これらはコントロールユニット１８へ入力される。
このコントロールユニット１８は、こうした機関の運転状態に応じて後述するように遮断弁開閉機構１３と可変動弁機構１６とを制御する一方、燃料噴射時期制御手段としても機能し、運転状態に応じた噴射時期に対応して、高圧燃料噴射弁６を駆動する。
【００１４】
吸気ポート形状としては、第１吸気ポート５ａは、ピストン１頂面上の燃焼室キャビティ２内に向かうため、第１吸気弁７ａ近くでシリンダ１７に対し直立する形状とし、第２，第３吸気ポート５ｂ，５ｃは、順タンブルガス流動１９を形成するため、第２，第３吸気弁７ｂ，７ｃ近くではストレート形状とする。
なお、本実施の形態に用いる可変動弁機構１６の一例を図６に示す。
【００１５】
次に本実施の形態の作用を説明する。
機関の運転条件が、低中速・低負荷域の成層燃焼領域では、図７に示すように可変動弁機構１６により第３吸気弁７ｃは停止し、第１吸気弁７ａおよび第２吸気弁７ｂのみリフトさせ、かつ、遮断弁開閉機構１３により第１吸気通路１０ａ内の遮断弁１２を閉鎖することで、筒内のガス流動を強めるとともに、第２吸気ポート５ｂから第２吸気弁７ｂを介して燃焼室３に入ってくる吸入空気は、第２吸気弁７ｂ方向から排気弁８方向へ向かい、さらに第３吸気弁７ｃ側へと回転するような強いスワール流９を形成し、燃料を少なくとも圧縮行程後期に噴射することで、前記スワール流９により燃料の点火プラグ４周りを成層化し、超希薄空燃比で運転し燃費の向上を図るとともに、かつ、燃料は点火プラグ４方向へ直接向かわず、一度ピストン１表面の燃焼室キャビティ２を介して点火プラグ４方向へ行くため、燃料微粒化、および気化が進み、点火プラグ４への液状燃料付着による失火は無く、安定して運転できるようになる。
【００１６】
機関の運転条件が、低中速・中負荷域の弱成層燃焼領域では、図５に示すように可変動弁機構１６により第１吸気弁７ａ、第２吸気弁７ｂおよび第３吸気弁７ｃをリフトさせ、かつ、遮断弁開閉機構１３により第１吸気通路１０ａ内の遮断弁１２を閉鎖することで、筒内のガス流動を若干弱めるとともに、第２吸気ポート５ｂから第２吸気弁７ｂを介して燃焼室３に入ってくる吸入空気と第３吸気ポート５ｃから第３吸気弁７ｃを介して燃焼室３に入ってくる吸入空気とが２つの順タンブルガス流動１９を生成し、燃料を少なくとも圧縮行程前期に噴射することで、前記２つの順タンブルガス流動１９の中間に燃料混合気の帯を生成する弱い成層化をし、希薄空燃比で運転し燃費の向上を図る。
【００１７】
機関の運転条件が、低中速・中負荷域の均質希薄燃焼領域では、図８に示すように、可変動弁機構１６により第３吸気弁７ｃは停止し、第１吸気弁７ａおよび第２吸気弁７ｂのみをリフトさせ、かつ、遮断弁開閉機構１３により第１吸気通路１０ａ内の遮断弁１２を開口することで、第２吸気ポート５ｂから第２吸気弁７ｂを介して燃焼室３に入ってくる吸入空気により生成される第２吸気弁７ｂ方向から排気弁８方向へ向かい、さらに第３吸気弁７ｃ側へと回転するような強いスワール流９を、第１吸気ポート５ａから第１吸気弁７ａを介して燃焼室３に入ってくる吸入空気流れにより弱め、燃料を少なくとも吸気行程に噴射することで、燃料混合気の均質化を図り、希薄空燃比で運転し燃費の向上を図る。
【００１８】
さらに、機関の運転条件が、高速・高負荷域の均質燃焼領域では、図９に示すように可変動弁機構１６により第１吸気弁７ａ、第２吸気弁７ｂをリフトさせ、かつ、遮断弁開閉機構１３により第１吸気通路１０ａ内の遮断弁１２を開口することで、吸気ポート面積を大きくし充填効率向上を図るとともに、燃料を少なくとも吸気行程時に噴射することで、筒内全体として均質な混合気を作り、出力領域も十分な性能を確保できる。
【００１９】
ところで、エバポ燃料をパージする場合において、図１０に示すように本実施の形態では、エバポ燃料を第１吸気ポート５ａから第１吸気弁７ａを介して直接ピストン１頂面上の燃焼室キャビティ２に向けて入れるため、機関の運転条件が、低速・低負荷域の成層燃焼時にエバポ燃料をパージする場合でも、スワール流９の中央であるピストン１頂面上の燃焼室キャビティ２内にパージガスは集中し、この燃焼室キャビティ２内で噴射燃料と混合し安定燃焼が可能となり、排気性能も悪化しなくなるので成立する。
【００２０】
また、機関の運転条件が、低中速・中負荷域の弱成層燃焼時にエバポ燃料をパージする場合も、図１１に示すように、２つの順タンブルガス流動１９の中央にパージガスは集中し、そのガス流動中間の燃料混合気の帯と混合し安定燃焼が可能となる。
【００２１】
そして、機関の運転条件が、低中速・中負荷域の均質希薄燃焼時、および高速・高負荷域の均質燃焼時にエバポ燃料をパージする場合は、図１２および図１３に示すように、燃料噴射が吸気行程時のためパージガスと噴射燃料は十分混合し、従来の吸気ポート燃料噴射機関と同様安定燃焼が可能となる。
【００２２】
さらに、機関の運転条件が、低速・低負荷域の成層燃焼時、および低中速・中負荷域の弱成層燃焼時は、スロットル弁開度が大きいため吸気ポート負圧は低下し、吸気ポートへのエバポ燃料のパージ流量は低下するが、本実施の形態によればエバポ燃料を第１吸気ポート５ａの遮断弁１２閉鎖時にこの遮断弁１２下流に入れるため、遮断弁１２下流の吸気ポート負圧は発達するのでパージ流量は低下しないという作用も得られる。
これまで説明した各燃焼を行わせる運転領域の一例を図１４に示す。
【００２４】
また、ガイド２０を設けることにより、図１５に示すように機関の運転条件が、低中速・低負荷域の成層燃焼領域、および低中速・中負荷域の弱成層燃焼領域でのエバポ燃料をパージする場合において、エバポ燃料は第１吸気ポート５ａの上部を流れ、主に第１吸気弁７ａの排気弁８側開口部から直接ピストン１頂面上の燃焼室キャビティ２に向けて入るため、スワール流９、あるいは２つの順タンブルガス流動１９の中央にあるピストン１頂面上の燃焼室キャビティ２内にパージガスはより多く集中し、前記燃焼室キャビティ２内で噴射燃料と混合し安定燃焼が可能となる。なお、図１６に他のガイド形状の例を示す。
【００２５】
ところで、応用例として、図１７に示すように、３つの吸気弁のリフト量に関して、第１吸気弁７ａのリフト量を第２吸気弁７ｂ、および第３吸気弁７ｃのリフト量よりも短くしてもよい。
【００２６】
これにより、機関の運転条件が、低中速・中負荷域の均質希薄燃焼領域での可変動弁機構１６により第３吸気弁７ｃは停止し、第１吸気弁７ａおよび第２吸気弁７ｂのみリフトさせ、かつ、遮断弁開閉機構１３により第１吸気通路１０ａ内の遮断弁１２を開口し、燃料を少なくとも吸気行程に噴射する領域と、高速・高負荷域の均質燃焼領域での可変動弁機構１６により第１吸気弁７ａ、第２吸気弁７ｂおよび第３吸気弁７ｃをリフトさせ、かつ、遮断弁開閉機構１３により第１吸気通路１０ａ内の遮断弁１２を開口し、燃料を少なくとも吸気行程時に噴射する領域では、第１吸気弁７ａと燃料噴霧との干渉が少なくなるため吸気弁７へのデポジット付着、すす発生が減少できる。
【００２７】
【発明の効果】
以上説明してきたように、請求項１記載の直接筒内噴射式火花点火機関にあっては、運転条件に応じた各ポートの開閉制御により、成層時の強いスワール流の形成と弱成層時の２つの順タンブルガス流動の形成、均質希薄燃焼時の弱いスワール流の形成、高回転・高負荷時の出力域での低吸気抵抗化の両立を図り、特定時期の燃料噴射により超希薄空燃比運転による燃費の向上とスロットル全開運転時の空気の充填効率増大化による出力性能向上の両立を図ることができるという効果がある。
また、成層時にエバポ燃料をパージする場合に、中央ポートから導入でき、かつ燃焼室内のガス流動を制御することが可能なため、パージガスをピストン頂面上の燃焼室内に集中でき、この燃焼室内で噴射燃料との混合を促進でき、燃焼が改善され、排気性能の悪化を防ぐことができるという効果がある。
さらに、上記のようにガイド溝を設けることで、機関の運転条件が、低中速・低負荷域の成層燃焼領域、および低中速・中負荷域の弱成層燃焼領域でのエバポ燃料をパージする場合において、エバポ燃料は中央第１吸気ポート上部を流れ、主に第１吸気弁の排気弁側開口部から直接ピストン頂面の燃焼室に向けて大半が入り、スワールガス流動、あるいは２つの順タンブル流ガス流動の中央に位置するピストン頂面上の燃焼室内により多く集中するのでこの燃焼室内で噴射燃料との混合が促進され、安定燃焼が可能となるという効果がある。
【００２８】
請求項２記載の直接筒内噴射式火花点火機関にあっては、機関の運転条件が、低中速・低負荷域の成層燃焼領域では、筒内のガス流動を強めるとともに、強いスワール流を形成し、燃料を少なくとも圧縮行程後期に噴射することで、燃料の点火プラグ周りの成層化を図り、超希薄空燃比で運転し燃費の向上を図るとともに、かつ、燃料は一度ピストン表面の燃焼室を介して、点火プラグ方向へ行くため、燃料微粒化、および気化が進み、点火プラグへの液状燃料付着による失火は無く、安定して運転できるようになるという効果がある。また、エバポ燃料をパージする場合でも、エバポ燃料は中央第１吸気ポートから直接ピストン頂面上の燃焼室内に向けて入れるので、スワールガス流動の中央であるピストン頂面上の燃焼室内にパージガスは集中し、前記燃焼室内で噴射燃料と混合し安定燃焼が可能となるという効果がある。
【００２９】
請求項３記載の直接筒内噴射式火花点火機関にあっては、機関の運転条件が、低中速・中負荷域の成層燃焼領域では、筒内のガス流動を若干弱めるとともに、燃焼室に入ってくる吸入空気が２つの順タンブル流ガス流動を生成し、燃料を少なくとも圧縮行程前期に噴射することで、前記２つのタンブル流ガス流動の中間に燃料混合気の帯を生成する弱い成層化をし、希薄空燃比で運転し、燃費の向上を図ることができるという効果がある。また、エバポ燃料をパージする場合も、２つの順タンブル流ガス流動の中央にパージガスは集中し、そのガス流動中間の燃料混合気の帯と混合し安定燃焼が可能となるという効果がある。
【００３０】
請求項４記載の直接筒内噴射式火花点火機関にあっては、機関の運転条件が、低中速・中負荷域の均質希薄燃焼領域では、強いスワール流を、中央第１吸気ポートから流入する燃焼室に入ってくる吸入空気流れにより弱め、燃料を少なくとも吸気行程に噴射することで、燃料混合気の均質化を図り、希薄空燃比で運転し、燃費の向上を図ることができるという効果がある。また、エバポ燃料をパージする場合は、燃料噴射が吸気行程時のために、パージガスと噴射燃料は十分混合し、従来の吸気ポート燃料噴射機関と同様に安定燃焼が可能となるという効果がある。
【００３１】
請求項５記載の直接筒内噴射式火花点火機関にあっては、機関の運転条件が、高速・高負荷域の均質燃焼領域では、吸気ポート面積を大きくし充填効率向上を図るとともに、燃料を少なくとも吸気行程時に噴射することで、混合気の均質化を図り、出力領域も十分な性能を確保できるという効果がある。またエバポ燃料をパージする場合は燃料噴射が吸気行程時のためパージガスと噴射燃料は十分混合し、従来の吸気ポート燃料噴射機関と同様に安定燃焼が可能となるという効果がある。
【００３２】
請求項６記載の直接筒内噴射式火花点火機関にあっては、中央第１吸気ポートから流入する流れはピストン頂面上の燃焼室内に向かい、第２、第３吸気ポートから流入する流れは順タンブルを形成するため、運転条件に応じた各ポートの開閉制御時に、運転条件に応じた要求ガス流動（成層時の強いスワール流の形成、弱成層時の２つの順タンブルガス流動の形成、均質希薄燃焼時の弱いスワール流の形成、高回転・高負荷時の出力域での低吸気抵抗化）を形成できるという効果がある。
【図面の簡単な説明】
【図１】本発明実施の形態の直接筒内噴射式火花点火機関の構成を示す図である。
【図２】実施の形態の直接筒内噴射式火花点火機関の構成を示す図である。
【図３】（ａ）は図２のＳ３−Ｓ３断面図、（ｂ）は（ａ）のＳ３ｂ−Ｓ３ｂ断面図である。
【図４】図２のＳ４−Ｓ４断面図である。
【図５】実施の形態の作用を説明する図である。
【図６】実施の形態の可変動弁機構１６の一例を示す図である。
【図７】実施の形態の作用を説明する図である。
【図８】実施の形態の作用を説明する図である。
【図９】実施の形態の作用を説明する図である。
【図１０】実施の形態の作用を説明する図である。
【図１１】実施の形態の作用を説明する図である。
【図１２】実施の形態の作用を説明する図である。
【図１３】実施の形態の作用を説明する図である。
【図１４】各燃焼を行わせる運転領域の一例を示す図である。
【図１５】実施の形態の作用を説明する図である。
【図１６】他のガイド形状の例を示す図である。
【図１７】実施の形態の応用例を説明する図である。
【図１８】従来の直接筒内噴射式火花点火機関を示す縦断面図である。
【図１９】従来の直接筒内噴射式火花点火機関を示す横断面図である。
【図２０】従来の直接筒内噴射式火花点火機関のシステム構成を示す図である。 [0001]
BACKGROUND OF THE INVENTION
The present invention relates to a direct in-cylinder spark ignition engine.
[0002]
[Prior art]
  As a conventional direct cylinder injection spark ignition engine, for example,FIG.FromFIG.There are some as shown in JP-A-5-79370. This includes a concave combustion chamber cavity 02 formed on the top surface of the piston 01 and a spark plug 04 inserted near the side wall of the combustion chamber cavity 02 at the time of ignition as the piston 01 rises. The first intake port 05a forming the type intake port and the second intake port 05b forming the straight type intake port extending straight. Each intake port 05a, 05b is connected to the collector 011 via an intake passage 010 formed in the intake manifold, and an intake control valve 012 is installed in the second intake passage 010b connected to the second intake port 05b. ing. Further, a high-pressure fuel injection valve 06 is installed below the intake port 05 and obliquely downward with respect to the combustion chamber 03. In this conventional example, the gas flow of the swirl flow 09 is generated by the opening / closing control 013 of the intake control valve 012 in a specific operation state, the fuel is stratified around the spark plug 04, and an ultra lean air-fuel ratio is obtained. Driving and improving fuel efficiency. In addition, 07 is an intake valve and 08 is an exhaust valve.
[0003]
[Problems to be solved by the invention]
However, in such a conventional direct in-cylinder spark ignition engine, since it is necessary to form a strong swirl flow 09 during stratification, it is strong only by closing the second intake port 05b by the intake control valve 012. Since the swirl flow 09 cannot be formed, the first intake port 05a has a helical shape.
For this reason, in the output region at the time of high rotation and high load, it becomes an intake resistance and the output performance is lowered. In the case of stratified combustion using the gas flow of the swirl flow 09 when purging the evaporative fuel at the time of stratification, the purge gas follows the gas flow of the swirl flow 09 through the first intake port 05a and enters the combustion chamber 03. Since the evaporative fuel is present outside the combustion chamber 03 for a long time and does not concentrate in the combustion chamber cavity 02 on the top surface of the piston 01, the combustion mixed with the injected fuel in the combustion chamber cavity 02 is difficult. As a result, the exhaust performance deteriorates.
The present invention has been made paying attention to such a conventional problem, and can perform a good purge at the time of stratified combustion and can directly improve the output at the time of high rotation and high load. It is to provide a spark ignition engine.
[0004]
[Means for Solving the Problems]
  In order to achieve the above object, according to the first aspect of the present invention, three intake ports are formed for one cylinder, and the flow of intake air flows through a central first intake port located at the center of the three intake ports. It is formed in a shape that goes directly to the concave part of the piston,Forming a guide groove along the flow direction of the intake air on the upper wall of the central first intake port;A shutoff valve is provided upstream of the central first intake port, and the central first intake port downstream of the shutoff valveNear the guide grooveProvided with an evaporative purge outlet, the second intake port and the third intake port located on both sides of the central first intake port are formed in a shape in which the flow of intake air generates a tumble flow in the combustion chamber, and the third intake port is formed. A variable valve mechanism that stops the operation of the intake valve that opens and closes according to the operating state, a shut-off valve opening and closing mechanism that controls opening and closing of the shut-off valve according to the operating state of the engine, and fuel injection according to the operating state of the engine And an injection timing control means for controlling the timing.
  According to the direct in-cylinder spark ignition engine according to claim 1, the formation of a strong swirl flow during stratification and the formation of two forward tumble gas flows during weak stratification by controlling the opening and closing of each port according to operating conditions. It achieves both a weak swirl flow at the time of homogeneous lean combustion and a low intake resistance in the output range at high rotation and high load, fuel efficiency improvement by ultra lean air-fuel ratio operation and full throttle opening by fuel injection at a specific time It is possible to achieve both improvement in output performance by increasing air charging efficiency during operation. Further, when purging the evaporative fuel during stratification, the purge gas can be concentrated in the combustion chamber on the piston top surface because it can be introduced from the central first port and the gas flow in the combustion chamber can be controlled. Mixing with injected fuel can be promoted indoors, combustion is improved, and exhaust performance can be prevented from deteriorating.
  In addition, by providing the guide groove as described above, the engine operating condition purges the evaporative fuel in the stratified combustion region in the low / medium / low load region and the weak stratified combustion region in the low / medium / medium load region. In this case, the evaporative fuel flows in the upper part of the central first intake port, mostly enters the combustion chamber on the top surface of the piston directly from the exhaust valve side opening of the first intake valve, swirl gas flow, or More concentrated in the combustion chamber on the top surface of the piston located at the center of the two forward tumble gas flows, mixing with the injected fuel is promoted in this combustion chamber, and stable combustion is possible.
[0005]
According to a second aspect of the present invention, in the direct in-cylinder spark ignition engine according to the first aspect, when the operating state of the engine is in a region where stratified combustion is performed to collect an air-fuel mixture near the spark plug, the variable valve The mechanism stops the operation of the intake valve of the third intake port, the shut-off valve opening / closing mechanism closes the shut-off valve of the central first intake port, and the injection timing control means sets the fuel injection timing to the late stage of the compression stroke. Features.
According to the direct in-cylinder spark ignition engine according to claim 2, in the stratified combustion region of the low, medium speed and low load region, the operating condition of the engine enhances the gas flow in the cylinder and forms a strong swirl flow. The fuel is injected at least at the later stage of the compression stroke, so that the fuel can be stratified around the spark plug and operated at an ultra lean air / fuel ratio to improve fuel efficiency. Therefore, fuel atomization and vaporization proceed, and there is no misfire due to liquid fuel adhering to the spark plug, so that stable operation is possible. Also, even when evaporative fuel is purged, the evaporative fuel enters the combustion chamber on the top surface of the piston directly from the central first intake port, so the purge gas does not enter the combustion chamber on the top surface of the piston, which is the center of the swirl gas flow. It concentrates and mixes with the injected fuel in the combustion chamber to enable stable combustion.
[0006]
According to a third aspect of the present invention, in the direct in-cylinder spark ignition engine according to the first or second aspect, when the engine is in a region where weakly stratified fuel collecting air-fuel mixture is collected near the spark plug, The valve mechanism operates the intake valve of the third intake port, the shut-off valve opening / closing mechanism closes the shut-off valve of the central first intake port, and the injection timing control means sets the fuel injection timing to the first stage of the compression stroke. And
According to the direct in-cylinder spark ignition engine according to claim 3, in the stratified combustion region of the low and medium speed / medium load region, the operating condition of the engine slightly weakens the gas flow in the cylinder and enters the combustion chamber. The incoming intake air generates two forward tumble flow flows and injects the fuel at least in the first half of the compression stroke, creating a weak stratification that creates a fuel mixture zone between the two tumble flow flows. In addition, driving with a lean air-fuel ratio can improve fuel efficiency. Also, when purging the evaporated fuel, the purge gas is concentrated at the center of the two forward tumble flow gas flows, and is mixed with the fuel mixture zone in the middle of the gas flow, thereby enabling stable combustion.
[0007]
According to a fourth aspect of the present invention, in the direct in-cylinder spark ignition engine according to any one of the first to third aspects, the homogeneous lean combustion in which the operating state of the engine forms a homogeneous lean air-fuel mixture in the combustion chamber. The variable valve mechanism stops the intake valve of the third intake port, the cutoff valve opening / closing mechanism opens the cutoff valve of the central first intake port, and the injection timing control means sets the fuel injection timing to the intake stroke. It is characterized by setting to.
According to the direct in-cylinder spark ignition engine of claim 4, when the engine operating condition is a homogeneous lean combustion region in a low, medium speed and medium load region, a strong swirl flow flows from the central first intake port. By weakening the flow of intake air entering the combustion chamber and injecting fuel at least during the intake stroke, the fuel mixture can be homogenized and operated at a lean air-fuel ratio to improve fuel efficiency. In addition, when the evaporated fuel is purged, since the fuel injection is in the intake stroke, the purge gas and the injected fuel are sufficiently mixed, and stable combustion is possible as in the conventional intake port fuel injection engine.
[0008]
According to a fifth aspect of the present invention, in the direct in-cylinder spark ignition engine according to the first to fourth aspects, it is possible when the operating state of the engine is in a region where homogeneous combustion is performed to form a homogeneous mixture in the combustion chamber. The variable valve mechanism operates the intake valve of the third intake port, the cutoff valve opening / closing mechanism opens the cutoff valve of the central first port, and the injection timing control means sets the fuel injection timing to the intake stroke. .
According to the direct in-cylinder spark ignition engine according to claim 5, in the homogeneous combustion region of the high speed and high load region, the operating condition of the engine is to increase the intake port area and improve the charging efficiency, and at least the fuel By injecting during the intake stroke, the mixture can be homogenized and sufficient performance can be ensured in the output region. Further, when purging the evaporated fuel, since the fuel injection is in the intake stroke, the purge gas and the injected fuel are sufficiently mixed, and stable combustion is possible as in the conventional intake port fuel injection engine.
[0009]
According to a sixth aspect of the present invention, in the direct in-cylinder spark ignition engine of the first to fifth aspects, the central first intake port has a shape that stands upright with respect to the cylinder and faces the concave portion of the piston. The intake port and the third intake port have a straight shape that generates a tumble flow in the combustion chamber.
According to the direct in-cylinder spark ignition engine of claim 6, the flow flowing in from the central first intake port is directed to the combustion chamber on the piston top surface, and the flow flowing in from the second and third intake ports is in order. In order to form a tumble, the required gas flow according to the operating conditions (formation of strong swirl flow during stratification, formation of two forward tumble gas flows during weak stratification, homogeneity) Formation of weak swirl flow during lean combustion and low intake resistance in the output range at high rotation and high load).
[0012]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
  1 to 4 show the implementation of the present invention.Form1 is a diagram showing a configuration of a direct in-cylinder injection spark ignition engine (hereinafter referred to as an engine).
  First, the configuration will be described. The engine of the present embodiment includes a combustion chamber cavity 2 having a recess formed in the top surface of the piston 1 and an ignition plug inserted into the cylinder head of the cylinder 17 facing the combustion chamber cavity 2. 4 and a high-pressure fuel injection valve 6 for directly injecting fuel into the cylinder obliquely downward with respect to the combustion chamber 3 at the lower part of the intake port 5. In the present embodiment, the three intake valves 7 and the intake ports 5 are formed for one cylinder, but the first intake valve connected to the first intake valve 7 a located at the center of the three intake valves 7. In the port 5a, the intake flow flowing in through the intake port isFIG. 3 (a)As shown in FIG. 2, the intake port shape is directed into the combustion chamber cavity 2 on the top surface of the piston 1. A cutoff valve 12 is provided in the first intake passage 10a upstream of the first intake port 5a, and an evaporative purge outlet 14 is provided downstream of the cutoff valve 12. Further, the second intake port 5b and the third intake port 5c connected to the two second intake valves 7b and the third intake valve 7c on both sides of the first intake valve 7a have an intake flow flowing in through the intake port, As shown in FIG. 5, the intake port shape is such that a forward tumble gas flow 19 is formed in the combustion chamber 3. A variable valve mechanism 16 and a shut-off valve opening / closing mechanism 13 are provided to open and close the first intake valve 7a, the second intake valve 7b, and the third intake valve 7c according to the operating conditions of the engine. Note that 8 is an exhaust valve, 10b is a second intake passage connected to the second intake port 5b, 10c is a third intake passage connected to the third intake port 5c, 11 is a collector, and 15 is an evaporation purge control mechanism.
  Further, FIG. 3B shows a cross section taken along line S3b-S3b of FIG. As shown in FIG. 3 (b), a guide 20 for inducing an intake air flow is provided above the intake port 5a as a cross-sectional shape of the first intake port 5a toward the combustion chamber cavity 2 on the top surface of the piston 1.
[0013]
The operating state and load of the engine are detected by an accelerator opening sensor 22, and the rotational speed is detected by a crank angle sensor 21, which are input to the control unit 18.
The control unit 18 controls the shut-off valve opening / closing mechanism 13 and the variable valve mechanism 16 as will be described later according to the operating state of the engine, and also functions as a fuel injection timing control unit. Corresponding to the injection timing, the high-pressure fuel injection valve 6 is driven.
[0014]
As the shape of the intake port, the first intake port 5a is directed into the combustion chamber cavity 2 on the top surface of the piston 1, so that the first intake port 5a is formed upright with respect to the cylinder 17 near the first intake valve 7a. The ports 5b and 5c have a straight shape near the second and third intake valves 7b and 7c in order to form the forward tumble gas flow 19.
An example of the variable valve mechanism 16 used in the present embodiment is shown in FIG.
[0015]
Next, the operation of this embodiment will be described.
In the stratified combustion region where the engine operating conditions are low, medium, and low load regions, the third intake valve 7c is stopped by the variable valve mechanism 16 as shown in FIG. 7, and the first intake valve 7a and the second intake valve are stopped. Only the valve 7b is lifted and the shut-off valve 12 in the first intake passage 10a is closed by the shut-off valve opening / closing mechanism 13, thereby strengthening the gas flow in the cylinder and moving the second intake valve 7b from the second intake port 5b. The intake air that enters the combustion chamber 3 through the second intake valve 7b forms a strong swirl flow 9 that rotates from the direction of the second intake valve 7b to the direction of the exhaust valve 8 and further toward the third intake valve 7c. The fuel is stratified around the spark plug 4 by the swirl flow 9 at least in the later stage of the compression stroke, and is operated at an ultra lean air-fuel ratio to improve fuel efficiency. Further, the fuel is directed directly toward the spark plug 4. First, fixie To go through the combustion chamber cavity 2 of first surface to the ignition plug 4 direction, fuel atomization and vaporization proceeds, misfire due to liquid adhesion of fuel to the ignition plug 4 is not, it is able to be operated stably.
[0016]
In the weak stratified combustion region where the engine is operating at low / medium speed / medium load range, the first intake valve 7a, the second intake valve 7b and the third intake valve 7c are controlled by the variable valve mechanism 16 as shown in FIG. By lifting and closing the shut-off valve 12 in the first intake passage 10a by the shut-off valve opening / closing mechanism 13, the gas flow in the cylinder is slightly weakened and the second intake port 5b through the second intake valve 7b. The intake air that enters the combustion chamber 3 and the intake air that enters the combustion chamber 3 from the third intake port 5c through the third intake valve 7c generate two forward tumble gas flows 19 to generate at least fuel. By injecting in the first half of the compression stroke, a weak stratification is generated to generate a fuel mixture zone in the middle of the two forward tumble gas flows 19, and the fuel consumption is improved by operating at a lean air-fuel ratio.
[0017]
As shown in FIG. 8, the third intake valve 7c is stopped by the variable valve mechanism 16, and the first intake valve 7a and the second intake valve 7c are operated when the engine operating condition is the homogeneous lean combustion region in the low, medium speed, and medium load regions. Only the intake valve 7b is lifted, and the shutoff valve opening / closing mechanism 13 opens the shutoff valve 12 in the first intake passage 10a, so that the combustion chamber 3 enters the combustion chamber 3 from the second intake port 5b via the second intake valve 7b. A strong swirl flow 9 is generated from the first intake port 5a through the first intake port 5a to the exhaust valve 8 direction from the second intake valve 7b direction and further toward the third intake valve 7c side. By weakening the intake air flow entering the combustion chamber 3 via the intake valve 7a and injecting the fuel at least in the intake stroke, the fuel mixture is homogenized and the fuel consumption is improved by operating at a lean air-fuel ratio. .
[0018]
Further, when the engine operating condition is a homogeneous combustion region in a high speed / high load region, the variable intake mechanism 16 lifts the first intake valve 7a and the second intake valve 7b as shown in FIG. By opening the shut-off valve 12 in the first intake passage 10a by the opening / closing mechanism 13, the intake port area is increased to improve the charging efficiency, and the fuel is injected at least during the intake stroke, so that the entire cylinder is homogeneous. A mixture can be created and sufficient performance can be secured in the output region.
[0019]
By the way, when the evaporation fuel is purged, as shown in FIG. 10, in this embodiment, the evaporation fuel is directly discharged from the first intake port 5a through the first intake valve 7a to the combustion chamber cavity 2 on the top surface of the piston 1. Therefore, even when the engine operating conditions purge the evaporative fuel during stratified combustion in the low speed / low load region, the purge gas is contained in the combustion chamber cavity 2 on the top surface of the piston 1, which is the center of the swirl flow 9. This is established because it concentrates and mixes with the injected fuel in the combustion chamber cavity 2 to enable stable combustion and the exhaust performance does not deteriorate.
[0020]
Also, when the engine operating conditions are purged of evaporative fuel at the time of low stratified combustion in the low, medium speed and medium load range, the purge gas is concentrated at the center of the two forward tumble gas flows 19, as shown in FIG. Mixing with the zone of the fuel gas mixture in the middle of the gas flow enables stable combustion.
[0021]
When the engine operating condition is to purge the evaporative fuel during homogeneous lean combustion in the low / medium speed / medium load region and homogeneous combustion in the high speed / high load region, as shown in FIG. 12 and FIG. Since the injection is performed during the intake stroke, the purge gas and the injected fuel are sufficiently mixed, and stable combustion is possible as in the conventional intake port fuel injection engine.
[0022]
In addition, when the engine operating conditions are stratified combustion in the low speed / low load range and weak stratified combustion in the low / medium speed / medium load range, the throttle port opening is large and the intake port negative pressure decreases. However, according to the present embodiment, the evaporative fuel is introduced downstream of the shutoff valve 12 when the shutoff valve 12 of the first intake port 5a is closed. Since the pressure develops, the purge flow rate does not decrease.
An example of the operation region in which each combustion described so far is performed is shown in FIG.
[0024]
  Further, by providing the guide 20, FIG.As shown in FIG. 3, when the engine operating conditions purge the evaporative fuel in the stratified combustion region in the low, medium speed / low load region and the weak stratified combustion region in the low, medium speed / medium load region, Since it flows in the upper part of the intake port 5a and mainly enters the combustion chamber cavity 2 on the top surface of the piston 1 directly from the opening on the exhaust valve 8 side of the first intake valve 7a, the swirl flow 9 or two forward tumble gases More purge gas is concentrated in the combustion chamber cavity 2 on the top surface of the piston 1 at the center of the flow 19 and is mixed with the injected fuel in the combustion chamber cavity 2 to enable stable combustion.FIG. 16 shows another example of the guide shape.
[0025]
  By the way, as an application example, as shown in FIG.Regarding the lift amounts of the three intake valves, the lift amount of the first intake valve 7a is shorter than the lift amounts of the second intake valve 7b and the third intake valve 7c.May.
[0026]
  ThisThe third intake valve 7c is stopped by the variable valve mechanism 16 in the homogeneous lean combustion region of the low, medium speed and medium load region, and only the first intake valve 7a and the second intake valve 7b are lifted. Further, the shutoff valve opening / closing mechanism 13 opens the shutoff valve 12 in the first intake passage 10a, and the variable valve mechanism 16 in the homogeneous combustion region of the high speed / high load region and the region where fuel is injected at least in the intake stroke. The first intake valve 7a, the second intake valve 7b, and the third intake valve 7c are lifted, and the cutoff valve 12 in the first intake passage 10a is opened by the cutoff valve opening / closing mechanism 13 to inject fuel at least during the intake stroke. In such a region, since the interference between the first intake valve 7a and the fuel spray is reduced, deposit adhesion and soot generation on the intake valve 7 can be reduced.
[0027]
【The invention's effect】
  As described above, in the direct in-cylinder spark ignition engine according to claim 1, the formation of a strong swirl flow during stratification and the weak stratification by the opening / closing control of each port according to the operating conditions. Two lean tidal gas flows, weak swirl flow during homogeneous lean combustion, and low intake resistance in the output range at high rotation and high load. There is an effect that it is possible to achieve both improvement of fuel efficiency by driving and improvement of output performance by increasing air charging efficiency at the time of throttle full opening operation.
  Further, when evaporative fuel is purged during stratification, the purge gas can be concentrated in the combustion chamber on the piston top surface because it can be introduced from the central port and the gas flow in the combustion chamber can be controlled. Mixing with the injected fuel can be promoted, combustion is improved, and deterioration of exhaust performance can be prevented.
  Furthermore, by providing the guide groove as described above, the engine operating conditions purge the evaporated fuel in the stratified combustion region in the low, medium and low load regions and the weak stratified combustion region in the low, medium and medium load regions. In this case, the evaporative fuel flows in the upper part of the central first intake port, and mostly enters from the opening on the exhaust valve side of the first intake valve directly toward the combustion chamber on the piston top surface. Since it concentrates more in the combustion chamber on the top surface of the piston located in the center of the forward tumble flow gas flow, mixing with the injected fuel is promoted in this combustion chamber, and stable combustion is possible.
[0028]
In the direct in-cylinder spark ignition engine according to claim 2, in the stratified combustion region where the engine is operated at a low, medium speed and low load region, the gas flow in the cylinder is strengthened and a strong swirl flow is generated. The fuel is injected at least in the late stage of the compression stroke to achieve stratification around the spark plug of the fuel, to improve fuel efficiency by operating at an ultra lean air-fuel ratio, and once the fuel is in the combustion chamber on the piston surface Therefore, fuel atomization and vaporization proceed, and there is no misfiring due to liquid fuel adhering to the spark plug, so that stable operation can be achieved. In addition, even when evaporative fuel is purged, the evaporative fuel enters directly from the central first intake port into the combustion chamber on the top surface of the piston, so that the purge gas does not enter the combustion chamber on the top surface of the piston, which is the center of swirl gas flow. There is an effect that the fuel is concentrated and mixed with the injected fuel in the combustion chamber to enable stable combustion.
[0029]
In the direct in-cylinder spark ignition engine according to claim 3, in the stratified combustion region where the engine is operated at a low, medium speed and medium load range, the gas flow in the cylinder is slightly weakened and the combustion chamber Incoming intake air creates two forward tumble gas flows and weak stratification that injects fuel at least in the first half of the compression stroke, creating a fuel mixture zone between the two tumble gas flows Thus, there is an effect that the fuel efficiency can be improved by operating at a lean air-fuel ratio. Also, when purging the evaporative fuel, the purge gas is concentrated at the center of the two forward tumble flow gas flows, and there is an effect that stable combustion is possible by mixing with the fuel mixture zone in the middle of the gas flow.
[0030]
In the direct in-cylinder spark ignition engine according to claim 4, when the operating condition of the engine is a homogeneous lean combustion region in a low / medium speed / medium load region, a strong swirl flow is introduced from the central first intake port. The effect is that the fuel mixture is homogenized by operating at a lean air-fuel ratio and fuel consumption can be improved by weakening the intake air flow entering the combustion chamber and injecting the fuel at least in the intake stroke. There is. Further, when purging the evaporated fuel, since the fuel injection is in the intake stroke, the purge gas and the injected fuel are sufficiently mixed, and there is an effect that stable combustion is possible as in the conventional intake port fuel injection engine.
[0031]
In the direct in-cylinder spark ignition engine according to claim 5, when the operating condition of the engine is a high-speed and high-load homogeneous combustion region, the intake port area is increased to improve the charging efficiency, and the fuel is supplied. By injecting at least during the intake stroke, there is an effect that the air-fuel mixture is homogenized and sufficient performance can be secured in the output region. Further, when the evaporated fuel is purged, since the fuel injection is in the intake stroke, the purge gas and the injected fuel are sufficiently mixed, and there is an effect that stable combustion is possible as in the conventional intake port fuel injection engine.
[0032]
In the direct cylinder injection type spark ignition engine according to claim 6, the flow flowing in from the central first intake port is directed to the combustion chamber on the piston top surface, and the flow flowing in from the second and third intake ports is In order to form a forward tumble, the required gas flow according to the operating conditions (formation of a strong swirl flow during stratification, formation of two forward tumble gas flows during weak stratification, This has the effect of forming a weak swirl flow during homogeneous lean combustion, and a low intake resistance in the output range at high rotation and high load.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a direct in-cylinder spark ignition engine according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a direct in-cylinder spark ignition engine according to an embodiment.
[Fig. 3](A) is S3-S3 sectional drawing of FIG. 2, (b) is S3b-S3b sectional drawing of (a).
4 is a cross-sectional view taken along line S4-S4 of FIG.
FIG. 5 is a diagram illustrating the operation of the embodiment.
FIG. 6 is a diagram illustrating an example of a variable valve mechanism 16 according to the embodiment.
FIG. 7 is a diagram illustrating the operation of the embodiment.
FIG. 8 is a diagram for explaining the operation of the embodiment.
FIG. 9 is a diagram illustrating the operation of the embodiment.
FIG. 10 is a diagram for explaining the operation of the embodiment.
FIG. 11 is a diagram illustrating the operation of the embodiment.
FIG. 12 is a diagram illustrating the operation of the embodiment.
FIG. 13 is a diagram illustrating the operation of the embodiment.
FIG. 14 is a diagram showing an example of an operation region in which each combustion is performed.
FIG. 15It is a figure explaining the effect | action of embodiment.
FIG. 16It is a figure which shows the example of another guide shape.
FIG. 17It is a figure explaining the application example of embodiment.
FIG. 18It is a longitudinal cross-sectional view which shows the conventional direct in-cylinder injection type spark ignition engine.
FIG. 19It is a cross-sectional view showing a conventional direct in-cylinder injection spark ignition engine.
FIG. 20It is a figure which shows the system configuration | structure of the conventional direct cylinder injection type spark ignition engine.

Claims

A combustion chamber having a recess formed on the top surface of the piston, an ignition plug provided facing the combustion chamber, and an injection valve for injecting fuel directly into the cylinder obliquely downward from the intake port side with respect to the combustion chamber In the direct in-cylinder injection spark ignition engine provided,
To form a three intake ports for one cylinder, three intake air flow of the central first inlet port located in the center of the intake port is formed in a shape directly toward the recess of the piston, the central first inlet port A guide groove is formed in the upper wall along the intake flow direction, a shut-off valve is provided upstream of the central first intake port , and an evaporative purge outlet is provided near the guide groove of the central first intake port on the downstream side of the shut-off valve. A second intake port and a third intake port located on both sides of the central first intake port are formed in a shape in which the flow of intake air generates a tumble flow in the combustion chamber, and an intake valve that opens and closes the third intake port A variable valve mechanism that stops operation according to the operating state, a shut-off valve opening / closing mechanism that controls opening / closing of the shut-off valve according to the operating state of the engine, and an injection that controls the fuel injection timing according to the operating state of the engine Timing control Direct cylinder injection type spark ignition engine, characterized in that it comprises a stage, a.

When the operating state of the engine is in a region where stratified combustion is performed to collect the air-fuel mixture in the vicinity of the spark plug, the variable valve mechanism stops the operation of the intake valve of the third intake port, and the shutoff valve opening / closing mechanism is the central first intake port 2. The direct in-cylinder spark ignition engine according to claim 1, wherein the shutoff valve is closed and the injection timing control means sets the fuel injection timing to the latter half of the compression stroke.

When the engine is in a region where weak stratified combustion is performed to collect the air-fuel mixture in the vicinity of the spark plug, the variable valve mechanism operates the intake valve of the third intake port, and the shut-off valve opening / closing mechanism is connected to the central first intake port. 3. The direct in-cylinder injection spark ignition engine according to claim 1, wherein the shutoff valve is closed, and the injection timing control means sets the fuel injection timing to the first half of the compression stroke.

When the operating state of the engine is in a region where homogeneous lean combustion is performed to form a homogeneous lean mixture in the combustion chamber, the variable valve mechanism stops the intake valve of the third intake port, and the shut-off valve opening / closing mechanism is the central first 4. The direct in-cylinder spark ignition engine according to claim 1, wherein the intake port shut-off valve is opened and the injection timing control means sets the fuel injection timing to the intake stroke.

When the operating state of the engine is in a region where homogeneous combustion forms a homogeneous mixture in the combustion chamber, the variable valve mechanism operates the intake valve of the third intake port, and the shut-off valve opening / closing mechanism is the central first port. 5. The direct in-cylinder injection spark ignition engine according to claim 1, wherein the shutoff valve is opened and the injection timing control means sets the fuel injection timing to the intake stroke.

The central first intake port has a shape that stands upright with respect to the cylinder and faces the concave portion of the piston, and the second intake port and the third intake port have a straight shape that generates a tumble flow in the combustion chamber. The direct in-cylinder injection spark ignition engine according to any one of claims 1 to 5 .