JP3845917B2

JP3845917B2 - Accumulated fuel injection system

Info

Publication number: JP3845917B2
Application number: JP29641196A
Authority: JP
Inventors: 雅史邑上; 哲也鳥谷尾
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 1996-11-08
Filing date: 1996-11-08
Publication date: 2006-11-15
Anticipated expiration: 2016-11-08
Also published as: JPH10141167A

Description

【０００１】
【発明の属する技術分野】
本発明はディーゼルエンジン用の燃料噴射装置に関し、特に高圧燃料を一種のサージタンクである蓄圧配管（以下コモンレールと言う。）に蓄圧し、この蓄圧された高圧燃料を電子制御によってディーゼル機関に噴射するようにした蓄圧式燃料噴射装置に関するものである。
【０００２】
【従来の技術】
従来より、高圧供給ポンプによってコモンレールに高圧燃料を加圧圧送して蓄圧すると共に、このコモンレールの高圧燃料を電子制御式の蓄圧式燃料噴射装置によって、ディーゼル機関に噴射するようにしたものは、特開平５−１３３２９６号公報に示されるように公知である。
【０００３】
上記構成の蓄圧式燃料噴射装置では、コモンレールに蓄圧された高圧燃料を噴射制御するための電磁弁は、電磁二方弁の構成をとっている。すなわち、コモンレールの高圧燃料が導入される制御室と低圧リーク回収通路の間に電磁弁が配設され、噴射時期になると制御室内の燃料を低圧リーク回収通路に開放する。その後噴射期間が終了すると、低圧リーク回収通路を遮断し、高圧燃料通路の高圧燃料を制御室に導く構成となっている。
【０００４】
しかしながら、上述の電磁二方弁は、制御室圧力がシート面積全面に作用するため、電磁弁を閉弁方向に付勢するためのバネ力が大きくなってしまい、バネ力に打ち勝って電磁二方弁を開弁方向に駆動するための電磁力も大きな力が必要となり、ソレノイド部分の小型化が困難となる。そこで、平面状の二つのシート部材のどちらかに燃料逃がし溝を構成することによって、シート平面に作用する油圧力を低減し、ソレノイドの小型化を可能とした構成を先に出願人は特願平７−１９０４６４号にて提案している。
【０００５】
このような構造の場合、開弁時の制御室圧力をコントロールする二つの絞り孔を配設した板状の制御室圧設定部材は、インジェクタボディの制御室部の開口する面に対して、ネジあるいはかしめなどの締結部を有する固定部材を用いて固定される。ここで、制御室圧設定部材の制御室と接する面には制御室の開口面積だけ燃料の圧力が作用する。制御室圧力は最高１５０ＭＰａにも達するため、固定部材による軸力が十分でないと、制御室圧設定部材が凸状に変形し、制御室圧設定部材とインジェクタボディ間、あるいは複数の制御室圧設定部材間に微小隙間を生じ、その隙間を軽油が浸透する。制御室の周囲には低圧リーク回収通路が構成されるが、この低圧リーク回収通路まで浸透が達した場合、燃料リーク量が増大し悪化する。また、制御室の周囲には高圧燃料導入通路も構成されるため、制御室圧設定部材の凸状の変形が高圧燃料導入通路に達した場合、制御室への流入燃料が増加するために、ノズルの開弁期間が短くなり、噴射量が減少する。
【０００６】
上述の如く、制御室圧設定部材とインジェクタボディ間のシール性不良は、蓄圧式燃料噴射装置の燃料リーク量低減、安定した噴射量特性を実現する上で、大きな問題点であった。
【０００７】
【発明が解決しようとする課題】
上記問題点に鑑み、本発明では制御室圧設定部材とインジェクタボディ間、あるいは複数の制御室圧設定部材間のシール性を向上することにより、燃料リーク量を低減し、制御室への流入燃料の増加に起因する噴射量の減少を防ぐと共に、燃料リーク量と噴射量の経時変化を低減した蓄圧式燃料噴射装置を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
上記課題を解決するため、本発明は請求項１ないし請求項４に記載の構成を採用する。
請求項１に記載の構成によれば制御室圧設定部材の固定部材から伝達された軸力の分布は、制御室内の高圧燃料による制御室圧設定部材の受圧面内に位置する為、制御室内の高圧燃料による制御室圧設定部材の凸状の変形を少なくし、制御室圧設定部材とインジェクタボディ間の軽油の浸透を防ぐことができる。すなわち、制御室の近傍に位置する低圧リーク回収通路への軽油の浸透を防ぐことができるため、蓄圧式燃料噴射装置の燃料リーク量の低減が可能となる。また、制御室の近傍に位置する高圧燃料導入通路と制御室の連通を防ぐこともできるため、制御室への燃料流入量の増加による噴射量増加も防ぐことができる。
【０００９】
また、制御室圧設定部材の凸状の変形を抑えることができるため、蓄圧式燃料噴射装置を長時間作動することにより進行する固定部材の塑性変形を低減することができる。従って、蓄圧式燃料噴射装置の長時間作動後にも制御室圧設定部材とインジェクタボディ間には微小隙間ができることは無く、蓄圧式燃料噴射装置を長時間作動させた場合に燃料リーク量が増加し、噴射量が減少することを防ぐことができる。
【００１０】
また、請求項２に記載の構成によれば、固定部材から制御室圧設定部材に対する軸力の分布をさらに制御室の中心軸に近づけることができるため、上記構成よりも制御室内の高圧燃料による制御室圧設定部材の凸状の変形を少なくすることができるため、更に制御室から低圧リーク回収通路への燃料リーク量および高圧燃料導入通路から制御室への燃料流入を防ぐことができる。
【００１１】
また、請求項３に記載の構成によれば、固定部材から制御室圧設定部材へ伝達される軸力は、制御室圧設定部材と固定部材間の接触抵抗と制御室圧設定部材をインジェクタボディへ押しつける力として作用するが、この構成により制御室圧設定部材と固定部材間の接触抵抗を低減することができるため、より大きな力で制御室圧設定部材をインジェクタボディへ固定することができる。従って、制御室内の高圧燃料による制御室圧設定部材の凸状の変形を低減するのに有効であり、制御室から低圧リーク回収通路への燃料リーク量および高圧燃料導入通路から制御室への燃料流入を防ぐことができる。
【００１２】
さらに、請求項４に記載の構成によれば、高圧燃料の油圧力が制御室圧設定部材に作用する箇所は制御室のみになるため、固定部材の制御室圧設定部材を固定する軸力に対抗する力は少なくなり、制御室圧設定部材の凸状の変形を低減することができる。従って、制御室から低圧リーク回収通路への燃料リーク量および高圧燃料導入通路から制御室への燃料流入を防ぐことができる。
【００１３】
上記のように、本発明によって、制御室圧設定部材とインジェクタボディ間、あるいは複数の制御室圧設定部材間のシール性を向上できるため、燃料リーク量を低減し、制御室流入燃料の増加に起因する噴射量の減少を防ぐことができると共に、これらの特性の経時変化を低減することができる。
【００１４】
【発明の実施の形態】
図１は、本発明の第１の実施形態を示す蓄圧式燃料噴射装置の中心軸に沿った全体側面断面図であり、図２は図１中の要部の拡大側面断面図である。図３は本発明の第１の実施形態に用いた電磁二方弁の詳細構造断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。
【００１５】
本発明の第１の実施形態の構造を図１、図２、図３を用いて説明する。
第１の実施形態の蓄圧式燃料噴射装置１は図示しないディーゼル内燃機関の燃焼室内へ間欠的に燃料を噴射する燃料噴射装置であって、高圧燃料を蓄圧する図示しないコモンレールから高圧燃料を導出する図示しない燃料配管を通して燃料の供給を受け、電子的に制御されてディーゼル機関に燃料を噴射する各気筒毎に設けられた蓄圧式燃料噴射装置である。
【００１６】
蓄圧式燃料噴射装置１は、噴射ノズル２の燃料噴射孔３を開閉するための噴射ノズル２のニードル弁４と、ニードル弁４に接触あるいは連結し、ニードル弁４を閉弁方向に付勢するためのバネ部材６を貫通する棒状のノズルプレッシャピン５と、ノズルプレッシャピン５に接触あるいは連結し、インジェクタボディ７と摺動自在に組み込まれた制御ピストン８と、高圧燃料導入通路９より分岐する制御室燃料導入通路１０と燃料低圧室１１に連通し、油圧力によって制御ピストン８とノズルプレッシャピン５を介してニードル弁４を閉弁方向に付勢するための燃料が蓄えられる制御室１２と、ニードル弁４の開弁時に燃料噴射孔３から噴射する高圧燃料を噴射ノズル２の燃料噴射孔３に導くための噴射ノズル燃料導入通路３９とを具備する。
【００１７】
制御室燃料導入通路１０と制御室１２との間には、制御室１２への導入燃料を制限するための第１の絞り孔１３が配設され、制御室１２と低圧室１１の間に第１の絞り孔１３より通路抵抗の小さい第２の絞り孔１４が配設されている。第１の絞り孔１３と第２の絞り孔１４はそれぞれ別の部材に配設され、第１の絞り孔１３は第１の制御室圧設定部材５２に、第２の絞り孔１４は第２の制御室圧設定部材５１に形成される。
【００１８】
第２の絞り孔１４と低圧室１１の間には、制御室１２の高圧燃料を開放、あるいは遮断するための、電磁コイル１５と電磁コイル１５から発生する電磁力により駆動されると共に、閉弁方向に付勢するためのバネ部材１６およびバネ力を伝達するプッシュロッド３３を有する電磁二方弁１７とを備えている。
電磁二方弁１７は、セラミック、または鋼の球の一部分に平面が加工された可動側シート部材１８と、ネジにより第２の制御室圧設定部材５１へ軸力を作用させるシリンダ１９と、シリンダ１９に摺動自在に組み込まれ、可動側シート部材１８を回転自在に包括する棒状可動部材２０と、棒状可動部材２０に連結あるいは一体で構成されたアーマチャ２１とリフト量を調整するための円筒状部材４１とからなる。ここでシリンダ１９の第２の制御室圧設定部材５１に接する端面１９ａは、制御室１２の第１の制御室圧設定部材５２との接触面５２ａよりも内側に少なくとも一部分が位置する。さらに電磁二方弁１７のシート部２２は、図３の詳細構造に示すように、電磁二方弁１７の可動側シート部材１８側と制御室１２を構成する第２の制御室圧設定部材５１側に設けられた２つの平面１８ａ、５１ａで構成された平面シート部からなり、平面１８ａ、５１ａを密着、あるいは所定の距離を隔てることによって、制御室１２の高圧燃料を開放、あるいは遮断制御を行う構造となっている。
【００１９】
燃料フィルタ２４は燃料中に含まれる不純物あるいは噴射管の脱着の際に混入した不純物を濾過し、蓄圧式燃料噴射装置内部の損傷を防ぐために設けられている。燃料フィルタ２４の外周面とインジェクタボディ７内周面の間の隙間は０．０２５ｍｍに設定され、この隙間に燃料を通すことで不純物を濾過する。
また、図１中の２５はノズルパッキンチップ、２６はノズルリテーニングナット、２７は電磁二方弁のコネクタ、２８は電磁二方弁１７のリテーニングナット、２９はリーク燃料回収用通路である。さらに、通路３１は制御ピストン８と噴射ノズル２のニードル弁４の摺動クリアランスからのリーク燃料を回収するための低圧リーク回収通路であり、第１の制御室圧設定部材５２と第２の制御室圧設定部材５１に配設された低圧通路５４、５３を介して燃料低圧室１１に連通している。また、燃料低圧室１１はシリンダ１９を連通する低圧通路３４と、アーマチャ２１を連通する低圧通路３５、プッシュロッド３３の中心を連通する低圧通路３６、電磁コイル１５の外周を連通する図示しない低圧通路、およびリーク燃料回収用通路２９に連通している。
【００２０】
第１の実施形態における各部寸法は以下の通りである。
第１の絞り孔１３の直径は０．２ｍｍ、第２の絞り孔１４の直径は０．３２ｍｍ、可動側シート部材１８の球径は２．０ｍｍ、可動側シート部材１８の平面部直径は１．６ｍｍ、球削り代は０．４ｍｍ、電磁二方弁１７のリフト量は０．１２ｍｍ、シリンダ１９の端面外径は１４．３ｍｍ、シリンダ１９の端面内径は４ｍｍ、制御室１２の内径は５ｍｍである。
【００２１】
また、可動側シート部材１８は棒状可動部材２０に対し、回転自在に組み付けられている。つまり、棒状可動部材２０の先端部に円筒状の突起４２が配設されており、その内径は可動側シート部材１８とのクリアランスが数μｍとなるように加工されている。また、円筒状の突起４２の内部底面には図示しない円錐状のくぼみが加工されており、この円錐状くぼみに可動側シート部材１８の球面が接触し、かつ棒状可動部材２０から飛び出すことがなく、かつ回転摺動性を損なうことがない所定のかしめ力で円筒状の突起４２がかしめられている。
【００２２】
次に第１の実施形態の作動を説明する。
高圧燃料は、先ずコモンレールから導出される図示しない燃料配管を通って、蓄圧式燃料噴射装置１の高圧燃料導入通路９に入り、制御室１２側と噴射ノズル２側のそれぞれの高圧燃料通路１０と３９に分岐され導入される。この時、噴射ノズル２のニードル弁４はノズルプレッシャピン５に取り付けられたバネ部材６によって閉弁方向に付勢されているため噴射は行われない。また、電磁二方弁１７も閉弁方向に付勢するバネ部材１６によって、閉弁状態を保っている。以上の状態で、徐々に高圧燃料導入通路９の圧力は上昇する。エンジン始動直後のこの圧力上昇速度は、約２５〜３０ＭＰａ／ｓｅｃ程度である。前記のノズルプレッシャピン５に取り付けられたバネ部材６がニードル弁４を閉弁方向に付勢することに加え、制御室１２に入った高圧燃料によって制御ピストン８は、ニードル弁４の閉弁方向に付勢する。従って電磁二方弁１７が開弁するまでは噴射ノズル２から燃料が噴射することは無い。これは、制御ピストン８の受圧面積とノズルニードル弁の受圧面積とに差があり、前者の方が大きいためである。
【００２３】
また、電磁二方弁１７を閉弁方向に付勢するためのバネ部材１６のセット荷重は６５Ｎに設定されており、蓄圧式燃料噴射装置１の使用時における最大制御室圧力１５０ＭＰａの場合の開弁方向への油圧荷重２０Ｎよりも大きく設定されているため、噴射ノズル２のニードル弁４と同様に油圧荷重によって開弁することもない。
【００２４】
この状態で電磁二方弁１７を開弁するため、電磁コイル１５に通電すると、電磁コイル１５から発生する電磁力により、アーマチャ２１が吸引される。この電磁力と制御室１２の圧力が可動側シート部材１８の受圧部に作用することにより発生する開弁方向に働く油圧力の総和が、閉弁方向に付勢するバネ部材１６のセット荷重より大きくなると開弁する。第１の実施例における電磁力は約１００Ｎに設定されているため、例えば最大噴射圧力が１５０ＭＰａだとすれば、上述の如く電磁コイル１５に開弁のための通電を行わない限り、必ず電磁二方弁１７は閉弁状態を保つようになっている。一旦、電磁コイル１５に通電がなされると電磁二方弁１７が開弁し、制御室１２の燃料は第２の絞り孔１４を介して燃料低圧室１１に流出し、プッシュロッド３３、アーマチャ２１、電磁コイル１５を貫通する低圧通路３４、３５、３６、２９およびユニオン６１を介して、図示しないリーク燃料回収用の配管に流れ込む。制御室１２の高圧燃料の流出が始まりしばらくすると、制御室１２の圧力は、高圧燃料導入通路９および噴射ノズル燃料導入通路３９の圧力の半分以下に低下する。これは、制御室１２からの流出燃料を規制するための第２の絞り孔１４の通路面積に比較し、制御室１２に導入される燃料を規制するための第１の絞り孔１３の通路面積が小さく構成されているためである。さらに制御室１２の圧力が下がると、噴射ノズル２のニードル弁４、制御ピストン８の油圧荷重、およびバネ部材６のセット荷重との力関係が逆転し、開弁方向への力が勝って、噴射ノズル２の燃料噴射孔３から燃料噴射が開始される。
【００２５】
上記状態が続き、噴射終了時期が来ると電磁コイル１５への通電が遮断する。この時、アーマチャ２１を吸引するための電磁力１００Ｎが０になるため、電磁二方弁１７を閉弁方向に付勢するバネ部材１６の力によって電磁二方弁１７は閉弁する。すると、制御室１２に高圧燃料導入通路９と制御室燃料導入通路１０を介して高圧燃料が導入され、徐々に制御室１２の圧力が電磁二方弁１７の開弁前の初期状態まで復帰してくる。この制御室１２の昇圧過程の途中で、油圧荷重とバネ部材６のセット荷重との力関係が逆転すると、噴射ノズル２のニードル弁４が閉弁し噴射が終了する。
【００２６】
以上の構成と作動を行う蓄圧式燃料噴射装置１において、高圧燃料導入通路９と制御室１２のあいだに位置する制御室１２への導入燃料を制限するための第１の絞り孔１３と、制御室１２と低圧通路３４、３５、３６、２９あるいは燃料低圧室１１の間に位置する第１の絞り孔１３より通路抵抗の小さい第２の絞り孔１４とを別々に配設する（もしくは一体に配設してもよい）制御室圧設定部材５１、５２と、インジェクタボディ７（あるいはインジェクタボディ７に締結されたネジ部材）にネジ、あるいはかしめなどで締結する制御室圧設定部材５１、５２の固定部材（シリンダ）１９との接触面は、少なくともその一部分が制御室圧設定部材５１、５２の制御室１２との接触面５２ａ内に位置する。つまり第１の実施形態においては、第２の制御室圧設定部材５１とシリンダ１９の接触面１９ａは、少なくとも一部分が第１の制御室圧設定部材５２の制御室１２との接触面５２ａよりも内側に位置する。
【００２７】
この構成について、その効果を説明する。
第１の実施形態との比較のために、シリンダ端面１９ａが第１の制御室圧設定部材５２の制御室１２との接触面５２ａ外だけに接触する場合の電磁二方弁１７付近の断面図を図４に示す。図４において（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図、（Ｃ）は第１の制御室圧設定部材５２の変形状態を示す説明図である。ここで、図３、図４のＡ−Ａ断面上に示されたクロスハッチング部分の面は、シリンダ１９と第２の制御室圧設定部材５１との接触面１９ａの作用位置である。第１の制御室圧設定部材５２の制御室１２との接触面５２ａに作用する圧力は、電磁二方弁１７の閉弁時には最大１５０ＭＰａに達するが、この圧力が第１の制御室圧設定部材５２の制御室１２に接した面５２ａに作用することにより約３ｋＮの油圧力が発生する。図４（Ａ）に示すようにシリンダ端面１９ａが接触面５２ａよりも外側だけに接触する場合、図４（Ｃ）のように、第１の制御室圧設定部材５２は制御室１２の反対方向に向かって凸状に変形し、インジェクタボディ７との間に微小隙間を生じる。また、第２の制御室圧設定部材５１は第１の制御室圧設定部材５２の面に配設された第１の絞り孔１３と制御室１２を連通する燃料導入通路５５内の高圧燃料によって制御室１２の反対方向に向かって凸状に変形し、第１の制御室圧設定部材５２との間に微小隙間を生じる。これら２箇所の微小隙間によって、以下に示す蓄圧式燃料噴射装置の性能の悪化が生じる。
【００２８】
第１は、インジェクタボディ７のバルブ側端面７ａに開口した低圧通路３１とシリンダ１９に設けられた低圧室１１を連通する低圧リーク回収通路５３、５４にまで制御室圧設定部材５１、５２双方の凸状変形による微小隙間が存在した場合、微小隙間から高圧燃料の漏れを生じ、蓄圧式燃料噴射装置の燃料リーク量が増加する。
【００２９】
第２は、インジェクタボディ７のバルブ側端面７ａに開口する制御室燃料導入通路１０にまで第１の制御室圧設定部材５２の凸状変形による微小隙間が存在した場合、第１の絞り孔１３以外に高圧燃料が制御室１２に流入し、制御室１２の流入流量が増加することである。すなわち、制御室圧の昇圧速度が上昇、および降圧速度が低下するため、ノズルの開弁時間が短くなり、噴射量が減少する。
【００３０】
しかし、図３に示すように、第２の制御室圧設定部材５１とシリンダ１９の接触面１９ａは、少なくともその一部分が第１の制御室圧設定部材５２の制御室１２との接触面５２ａ内に位置する第１の実施形態の場合、シリンダ端面１９ａに作用する軸力が、制御室１２の高圧燃料の受圧面５２ａよりも内側に作用するため、制御室圧設定部材５１、５２双方の凸状の変形は少なく、微小隙間が低圧リーク回収通路５３、５４および制御室燃料導入通路１０まで達することを防止することができる。従って、第１の制御室圧設定部材５２とインジェクタボディ７間の燃料リークは発生せず、蓄圧式燃料噴射装置の低リーク量化を実現できると共に、制御室１２と制御室燃料導入通路１０が連通することもなく、噴射量の減少を防ぐことができる。
【００３１】
図５は図４のシリンダ端面１９ａが第１の制御室圧設定部材５２の制御室１２との接触面５２ａよりも外側だけに接触する場合と、図３の第１の実施形態に相当する場合とで、燃料リーク量増加量、噴射量増加量とが各々時間の経過とともにどのように変化したかを示すもので、図５の（ａ）と（ｂ）はそれぞれ、図４のシリンダ端面１９ａが第１の制御室圧設定部材５２の制御室１２との接触面５２ａよりも外側だけに接触する場合と、図３の第１の実施形態に相当する場合のリーク量、噴射量の増加量の経時変化を示している。
【００３２】
図５からわかるように、前者の場合である（ａ）のリーク量は３００〜４００時間を境に急増し、噴射量は４００時間まで徐々に減少している。これは、０〜４００時間の間に制御室１２の油圧力によって第１の制御室圧設定部材５２とインジェクタボディ７の間の微小隙間が徐々に増加し、作動時間の経過に従って制御室燃料導入通路１０から制御室１２へ流入する燃料が増加したために噴射量が減少したことを示している。つまり、第１の制御室圧設定部材５２が凸状に変形し、第１の制御室圧設定部材５２とインジェクタボディ７の間に生じた微小隙間に軽油が浸透することにより、第１の制御室圧設定部材５２の受圧面積は凸状に変形する前よりもさらに大きくなるため、作動時間が経過するにつれてさらに第１の制御室圧設定部材５２とインジェクタボディ７の微小隙間が大きくなってゆくことを示している。しかし、４００時間付近で微小隙間を浸透する軽油はリーク回収通路３１に到達するため、これ以上、第１の制御室圧設定部材５２の受圧面積は増えることがなく、微小隙間の成長も止まる。従って、制御室１２への燃料流入量も増加しなくなるため、噴射量は減少しなくなる。
【００３３】
一方、第１の実施形態の構成である（ｂ）の場合は長時間作動しても、ほとんど燃料リーク量が増加することもなく、噴射量が減少することもない。つまり、第２の制御室圧設定部材５１とシリンダ１９との接触面１９ａの一部分を第１の制御室圧設定部材５２の制御室１２との接触面５２ａ内に位置させたことによって、第１の制御室圧設定部材が凸状に変形することを防止することができるため、第１の制御室圧設定部材５２の受圧面積が作動時間の経過に従って増加することがないことを示している。このように、第１の実施形態の構成によって、燃料リーク量の増加、噴射量の減少などの蓄圧式燃料噴射装置１の性能の経時変化を低減することができる。
【００３４】
上述の如く、本願発明を採用した蓄圧式燃料噴射装置１は、二つの制御室圧設定部材５１、５２の有する高圧シール面の漏れをなくすと共に、制御室１２への第１の絞り孔１３以外からの燃料流入を防ぐことができるため、燃料リーク量を小さく抑えることができ、制御室１２への第１の絞り孔１３以外からの燃料流入に起因する噴射量減少を防止することができる。さらには、長時間作動後にも上記効果を得ることができ、特性の経時変化が少なく、信頼性の高い蓄圧式燃料噴射装置を実現することができる。
【００３５】
本発明の第２の実施形態について次に説明する。図６は本発明の第２の実施形態に用いた電磁二方弁の詳細構造の断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。ここで、図６のＡ−Ａ断面図である（Ｂ）上に示されたクロスハッチング部分の面は、シリンダ１９と第２の制御室圧設定部材５１との接触面１９ａの作用位置である。
【００３６】
第２の実施形態では、第２の制御室圧設定部材５１とシリンダ１９の接触面１９ａは、第１の制御室圧設定部材５２の制御室１２との接触面５２ａ内のみに位置する形状であり、その他の構造は第１の実施形態と同じである。
次に第２の実施形態の作用・効果を説明する。上記第２の実施形態の構成を有する場合、シリンダ端面１９ａに作用する軸力の全てが、制御室１２の高圧燃料の受圧面５２ａ内に作用するため、制御室圧設定部材５１、５２双方の凸状の変形を完全に無くすことができ、制御室１２と低圧リーク回収通路５３、５４および制御室燃料導入通路１０が連通するのを防止することができる。特に、第２の制御室圧設定部材５１とシリンダ１９の接触面１９ａの少なくとも一部分が第１の制御室圧設定部材５２の制御室１２との接触面５２ａよりも内側に位置する第１の実施形態を用いても制御室圧設定部材５１、５２双方の凸状の変形を防止できない場合、上記第２の実施形態の構成を用いることは有効である。
【００３７】
このように、第２の実施形態の構成を用いることにより、第１の制御室圧設定部材５２とインジェクタボディ７間の燃料リークは発生せず、蓄圧式燃料噴射装置の低リーク量化を実現できると共に、制御室１２と制御室燃料導入通路１０が連通することも無く、噴射量の減少を防ぐことができる。
次に、本発明の第３の実施形態について説明する。図７は本発明の第３の実施形態に用いた電磁二方弁の詳細構造の断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。ここで、図６のＡ−Ａ断面図である（Ｂ）上に示されたクロスハッチング部分の面は、シリンダ１９と第２の制御室圧設定部材５１との接触面１９ａの作用位置である。
【００３８】
第３の実施形態は、第２の制御室圧設定部材５１とシリンダ１９の接触面１９ａが、制御室１２の中心軸を中心に回転する方向に連続する形状であり、その他の構造は第１の実施形態と同じである。なお、制御室圧設定部材５１、５２は共にインジェクタボディ７に対して、図示しない２本のピンによって位置決めされた状態で取り付けられている。
【００３９】
次に第３の実施形態の作用・効果を説明する。図７中の構成のように、シリンダ１９とインジェクタボディ７にネジ部を有し、これらの締結力によって制御室圧設定部材５１、５２を固定する場合、シリンダ１９と第２の制御室圧設定部材５１の接触面１９ａには、シリンダ１９が回転することによる摩擦抵抗が働き、シリンダ１９が第２の制御室圧設定部材５１を抑えようとする軸力が減少する。従って、シリンダ１９と第２の制御室圧設定部材５１の接触面１９ａの摩擦抵抗が少ない程、シリンダ１９が第２の制御室圧設定部材５１を抑えようとする軸力が大きく、制御室圧設定部材５１、５２双方の凸状の変形を低減することができ、制御室１２と低圧リーク回収通路５３、５４および制御室燃料導入通路１０が連通するのを防止することができる。
【００４０】
従って、第３の実施形態の構成を有する図７では、シリンダ１９と第２の制御室圧設定部材５１の接触面１９ａが制御室１２の中心軸を中心に回転する方向に不連続な形状よりも、シリンダ１９と第２の制御室圧設定部材５１の接触面１９ａの摩擦抵抗を少なくできるため、制御室１２と低圧リーク回収通路５３、５４および制御室燃料導入通路１０の連通を防止する効果を増すことができる。なお、シリンダ１９と第２の制御室圧設定部材５１の接触面１９ａが制御室１２の中心軸を中心に回転する方向に不連続な形状とは、例えば図２、図３、図５に示すようにシリンダ１９と第２の制御室圧設定部材５１の接触面１９ａに、筒状の形を有する制御室１２の放線方向に溝、孔等を有し、接触面１９ａが制御室１２の中心軸を中心に回転する方向に対して横切る溝、孔等で分割された二つの面で構成されるような場合である。
【００４１】
次に、本発明の第４の実施形態について説明する。図８は、本発明の第４の実施形態に用いた電磁二方弁の詳細構造の断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。ここで、図８のＡ−Ａ断面図である（Ｂ）上に示されたクロスハッチング部分の面は、第２の制御室圧設定部材５１に対する高圧燃料の油圧力の作用位置である。第４の実施形態は、第１の絞り孔１３がインジェクタボディ７に配設されるため、第１の制御室圧設定部材５２は存在せず、第２の制御室圧設定部材５１とインジェクタボディ７に開口した制御室１２との接触面５２ａ以外には高圧燃料の作用する面が無い構成である。なお、その他の構造は第１の実施形態と同じである。
【００４２】
次に、第４の実施形態の作用・効果を説明する。図３に示すように第１の制御室圧設定部材５２および第２の制御室圧設定部材５１の二つが存在する場合、制御室１２内の高圧燃料は制御室１２と第１の制御室圧設定部材５２との接触面５２ａと、第１の絞り孔１３と制御室１２間に配設された高圧通路５５と第２の制御室圧設定部材５１との接触面５５ａに作用する。従って、二つの接触面５２ａ、５５ａに作用する油圧力が、第１の制御室圧設定部材５２および第２の制御室圧設定部材５１を凸状に変形させる力として働くが、第１の制御室圧設定部材５２および第２の制御室圧設定部材５１の凸状変形を小さくし、第１の制御室圧設定部材５２と第２の制御室圧設定部材５１間、あるいは第１の制御室圧設定部材５２とインジェクタボディ７間の連通を防ぐためには、接触面５２ａ、５５ａの面積を可能な限り小さくする必要がある。第４の実施形態の構成では、高圧燃料の作用する部分が第２の制御室圧設定部材５１と制御室１２との接触面５２ａのみになるため、第２の制御室圧設定部材５１を凸状に変形させる力は少なくなり、第２の制御室圧設定部材５１の凸状の変形を低減することができる。従って、制御室１２から低圧リーク回収通路３１への燃料リーク量および制御室燃料導入通路１０から制御室１２への燃料流入を防ぐことができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態を示す蓄圧式燃料噴射装置の中心軸に沿った全体側面断面図である。
【図２】図１中の要部側面断面図である。
【図３】本発明の第１の実施形態に用いた電磁二方弁の詳細構造断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。
【図４】第１の実施形態との比較のために、シリンダ端面１９ａが第１の制御室圧設定部材５２の制御室１２との接触面５２ａよりも外側だけに接触する場合の電磁二方弁１７付近の断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図、（Ｃ）は第１の制御室圧設定部材５２の変形状態を示す説明図である。
【図５】図４のシリンダ端面１９ａが第１の制御室圧設定部材５２の制御室１２との接触面５２ａよりも外側だけに接触する場合と、図３の第１の実施形態に相当する場合とで、燃料リーク量増加量、噴射量増加量とが各々時間の経過とともにどのように変化したかを示すグラフである。
【図６】本発明の第２の実施形態に用いた電磁二方弁の詳細構造の断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。
【図７】本発明の第３の実施形態に用いた電磁二方弁の詳細構造の断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。
【図８】本発明の第４の実施形態に用いた電磁二方弁の詳細構造の断面図であり、（Ａ）は中心軸に沿った側面断面図、（Ｂ）は（Ａ）中のＡ−Ａ断面図である。
【符号の説明】
１蓄圧式燃料噴射装置
２噴射ノズル
３燃料噴射孔
４ニードル弁
７インジェクタボディ
８制御ピストン
９高圧燃料導入通路
１１燃料低圧室
１２制御室
１３第１の絞り孔
１４第２の絞り孔
１５電磁コイル
１６バネ部材
１７電磁二方弁
１９ガイド部材、固定部材（シリンダ）
２０可動部材（棒状可動部材）
２９燃料低圧通路（リーク燃料回収用通路）
３１低圧リーク回収通路
３４、３５、３６燃料低圧通路
５１第２の制御室圧設定部材
５２第１の制御室圧設定部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device for a diesel engine, and in particular, accumulates high-pressure fuel in a pressure accumulation pipe (hereinafter referred to as a common rail) that is a kind of surge tank, and injects the accumulated high-pressure fuel into the diesel engine by electronic control. The present invention relates to a pressure accumulation type fuel injection device.
[0002]
[Prior art]
Conventionally, high-pressure fuel is pressurized and pumped to a common rail by a high-pressure supply pump, and the high-pressure fuel in the common rail is injected into a diesel engine by an electronically controlled accumulator fuel injection device. It is known as shown in Kaihei 5-133296.
[0003]
In the pressure accumulation type fuel injection device having the above configuration, the electromagnetic valve for controlling injection of the high pressure fuel accumulated in the common rail has a configuration of an electromagnetic two-way valve. That is, a solenoid valve is disposed between the control chamber into which the high-pressure fuel of the common rail is introduced and the low-pressure leak recovery passage, and the fuel in the control chamber is opened to the low-pressure leak recovery passage at the injection timing. Thereafter, when the injection period ends, the low pressure leak recovery passage is shut off, and the high pressure fuel in the high pressure fuel passage is guided to the control chamber.
[0004]
However, in the above-described electromagnetic two-way valve, since the control chamber pressure acts on the entire seat area, the spring force for urging the electromagnetic valve in the valve closing direction increases, and the two-way electromagnetic force is overcome by overcoming the spring force. The electromagnetic force for driving the valve in the valve opening direction also requires a large force, which makes it difficult to reduce the size of the solenoid part. Therefore, the applicant has already filed a patent application for a configuration in which a fuel relief groove is formed in one of the two flat sheet members, thereby reducing the hydraulic pressure acting on the plane of the seat and making the solenoid smaller. Proposed in Hei 7-190464.
[0005]
In the case of such a structure, the plate-like control chamber pressure setting member provided with two throttle holes for controlling the control chamber pressure when the valve is opened is screwed against the opening surface of the control chamber portion of the injector body. Or it fixes using the fixing member which has fastening parts, such as caulking. Here, the pressure of the fuel acts on the surface of the control chamber pressure setting member in contact with the control chamber by the opening area of the control chamber. Since the control chamber pressure reaches a maximum of 150 MPa, if the axial force by the fixing member is not sufficient, the control chamber pressure setting member deforms into a convex shape, and the control chamber pressure setting member and the injector body or a plurality of control chamber pressure settings A minute gap is formed between the members, and light oil penetrates the gap. A low pressure leak recovery passage is formed around the control chamber. When the penetration reaches the low pressure leak recovery passage, the amount of fuel leak increases and deteriorates. In addition, since the high pressure fuel introduction passage is also configured around the control chamber, when the convex deformation of the control chamber pressure setting member reaches the high pressure fuel introduction passage, the inflow fuel to the control chamber increases. The nozzle opening period is shortened and the injection amount is reduced.
[0006]
As described above, the poor sealing performance between the control chamber pressure setting member and the injector body is a serious problem in reducing the amount of fuel leak and the stable injection amount characteristic of the accumulator fuel injection device.
[0007]
[Problems to be solved by the invention]
In view of the above problems, the present invention improves the sealing performance between the control chamber pressure setting member and the injector body or between the plurality of control chamber pressure setting members, thereby reducing the amount of fuel leakage and inflowing fuel into the control chamber. It is an object of the present invention to provide an accumulator type fuel injection device that prevents a decrease in injection amount due to an increase in fuel flow rate and that reduces a change in fuel leak amount and injection amount over time.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention employs a configuration according to claims 1 to 4.
According to the configuration of the first aspect, since the distribution of the axial force transmitted from the fixed member of the control chamber pressure setting member is located within the pressure receiving surface of the control chamber pressure setting member by the high pressure fuel in the control chamber, The convex deformation of the control chamber pressure setting member due to the high pressure fuel can be reduced, and the penetration of light oil between the control chamber pressure setting member and the injector body can be prevented. That is, since light oil can be prevented from penetrating into the low-pressure leak recovery passage located in the vicinity of the control chamber, it is possible to reduce the amount of fuel leak in the accumulator fuel injection device. Further, since it is possible to prevent communication between the high pressure fuel introduction passage located in the vicinity of the control chamber and the control chamber, an increase in the injection amount due to an increase in the amount of fuel flowing into the control chamber can also be prevented.
[0009]
Further, since the convex deformation of the control chamber pressure setting member can be suppressed, it is possible to reduce the plastic deformation of the fixing member that is advanced by operating the pressure accumulation type fuel injection device for a long time. Therefore, there is no minute gap between the control chamber pressure setting member and the injector body even after the accumulator fuel injector is operated for a long time, and the amount of fuel leakage increases when the accumulator fuel injector is operated for a long time. It is possible to prevent the injection amount from decreasing.
[0010]
Further, according to the configuration of the second aspect, the distribution of the axial force from the fixed member to the control chamber pressure setting member can be made closer to the central axis of the control chamber. Since the convex deformation of the control chamber pressure setting member can be reduced, the amount of fuel leak from the control chamber to the low pressure leak recovery passage and the fuel inflow from the high pressure fuel introduction passage to the control chamber can be prevented.
[0011]
According to the third aspect of the present invention, the axial force transmitted from the fixed member to the control chamber pressure setting member determines the contact resistance between the control chamber pressure setting member and the fixed member and the control chamber pressure setting member from the injector body. However, this configuration can reduce the contact resistance between the control chamber pressure setting member and the fixing member, so that the control chamber pressure setting member can be fixed to the injector body with a larger force. Therefore, it is effective in reducing the convex deformation of the control chamber pressure setting member due to the high pressure fuel in the control chamber, the amount of fuel leak from the control chamber to the low pressure leak recovery passage, and the fuel from the high pressure fuel introduction passage to the control chamber. Inflow can be prevented.
[0012]
Furthermore, according to the configuration of the fourth aspect, since the location where the oil pressure of the high pressure fuel acts on the control chamber pressure setting member is only the control chamber, the axial force for fixing the control chamber pressure setting member of the fixing member is reduced. The opposing force is reduced, and the convex deformation of the control chamber pressure setting member can be reduced. Therefore, the amount of fuel leak from the control chamber to the low pressure leak recovery passage and the fuel inflow from the high pressure fuel introduction passage to the control chamber can be prevented.
[0013]
As described above, according to the present invention, the sealing performance between the control chamber pressure setting member and the injector body or between the plurality of control chamber pressure setting members can be improved, thereby reducing the amount of fuel leakage and increasing the fuel flowing into the control chamber. It is possible to prevent a decrease in the injection amount due to this, and it is possible to reduce a change with time in these characteristics.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an overall side cross-sectional view along the central axis of a pressure-accumulation fuel injection device showing a first embodiment of the present invention, and FIG. 2 is an enlarged side cross-sectional view of the main part in FIG. FIG. 3 is a detailed cross-sectional view of the electromagnetic two-way valve used in the first embodiment of the present invention, (A) is a side cross-sectional view along the central axis, and (B) is A- in FIG. It is A sectional drawing.
[0015]
The structure of the 1st Embodiment of this invention is demonstrated using FIG.1, FIG.2, FIG.3.
The pressure accumulation fuel injection device 1 of the first embodiment is a fuel injection device that intermittently injects fuel into a combustion chamber of a diesel internal combustion engine (not shown), and derives high pressure fuel from a common rail (not shown) that accumulates high pressure fuel. It is a pressure accumulation type fuel injection device provided for each cylinder that receives fuel supply through a fuel pipe (not shown) and injects fuel into a diesel engine under electronic control.
[0016]
The accumulator type fuel injection device 1 is in contact with or connected to the needle valve 4 of the injection nozzle 2 for opening and closing the fuel injection hole 3 of the injection nozzle 2 and urges the needle valve 4 in the valve closing direction. The rod-shaped nozzle pressure pin 5 that penetrates the spring member 6 for contact, the control piston 8 that is in contact with or connected to the nozzle pressure pin 5 and slidably incorporated in the injector body 7, and the high pressure fuel introduction passage 9 are branched. A control chamber 12 that communicates with the control chamber fuel introduction passage 10 and the fuel low pressure chamber 11 and stores fuel for energizing the needle valve 4 in the valve closing direction via the control piston 8 and the nozzle pressure pin 5 by the oil pressure; And an injection nozzle fuel introduction passage 39 for guiding high-pressure fuel injected from the fuel injection hole 3 to the fuel injection hole 3 of the injection nozzle 2 when the needle valve 4 is opened.
[0017]
A first throttle hole 13 for restricting fuel introduced into the control chamber 12 is disposed between the control chamber fuel introduction passage 10 and the control chamber 12, and the first throttle hole 13 is disposed between the control chamber 12 and the low pressure chamber 11. A second throttle hole 14 having a passage resistance smaller than that of the first throttle hole 13 is provided. The first throttling hole 13 and the second throttling hole 14 are disposed in different members, respectively, the first throttling hole 13 is in the first control chamber pressure setting member 52, and the second throttling hole 14 is in the second. The control chamber pressure setting member 51 is formed.
[0018]
Between the second throttle hole 14 and the low pressure chamber 11, it is driven by an electromagnetic force generated from the electromagnetic coil 15 and the electromagnetic coil 15 for closing or closing the high pressure fuel in the control chamber 12 and is closed. A spring member 16 for biasing in the direction and an electromagnetic two-way valve 17 having a push rod 33 for transmitting the spring force are provided.
The electromagnetic two-way valve 17 includes a movable side sheet member 18 having a flat surface formed on a part of a ceramic or steel ball, a cylinder 19 that applies an axial force to the second control chamber pressure setting member 51 by a screw, A rod-shaped movable member 20 that is slidably incorporated in the movable member 19 and includes the movable-side sheet member 18 rotatably, and an armature 21 connected to or integrally formed with the rod-shaped movable member 20 and a cylindrical shape for adjusting the lift amount. It consists of member 41. Here, at least a part of the end surface 19 a that contacts the second control chamber pressure setting member 51 of the cylinder 19 is located inside the contact surface 52 a of the control chamber 12 with the first control chamber pressure setting member 52. Further, as shown in the detailed structure of FIG. 3, the seat portion 22 of the electromagnetic two-way valve 17 includes a second control chamber pressure setting member 51 that constitutes the control chamber 12 and the movable seat member 18 side of the electromagnetic two-way valve 17. It consists of a flat sheet portion composed of two flat surfaces 18a and 51a provided on the side, and the high pressure fuel in the control chamber 12 is opened or shut off by closely contacting the flat surfaces 18a and 51a or separating them by a predetermined distance. It has a structure to do.
[0019]
The fuel filter 24 is provided to filter impurities contained in the fuel or impurities mixed when the injection pipe is detached, thereby preventing damage inside the accumulator fuel injection device. The gap between the outer peripheral surface of the fuel filter 24 and the inner peripheral surface of the injector body 7 is set to 0.025 mm, and impurities are filtered by passing fuel through the gap.
1, 25 is a nozzle packing tip, 26 is a nozzle retaining nut, 27 is a connector of an electromagnetic two-way valve, 28 is a retaining nut of the electromagnetic two-way valve 17, and 29 is a leak fuel collecting passage. Further, the passage 31 is a low-pressure leak recovery passage for recovering leak fuel from the sliding clearance of the control piston 8 and the needle valve 4 of the injection nozzle 2, and includes the first control chamber pressure setting member 52 and the second control. The fuel pressure low pressure chamber 11 communicates with low pressure passages 54 and 53 disposed in the chamber pressure setting member 51. The fuel low pressure chamber 11 includes a low pressure passage 34 that communicates with the cylinder 19, a low pressure passage 35 that communicates with the armature 21, a low pressure passage 36 that communicates with the center of the push rod 33, and a low pressure passage (not shown) that communicates with the outer periphery of the electromagnetic coil 15. , And a leak fuel recovery passage 29.
[0020]
The dimensions of each part in the first embodiment are as follows.
The diameter of the first throttle hole 13 is 0.2 mm, the diameter of the second throttle hole 14 is 0.32 mm, the spherical diameter of the movable side sheet member 18 is 2.0 mm, and the diameter of the plane portion of the movable side sheet member 18 is 1. .6 mm, ball shaving allowance is 0.4 mm, electromagnetic two-way valve 17 lift is 0.12 mm, cylinder 19 end face outer diameter is 14.3 mm, cylinder 19 end face inner diameter is 4 mm, and control chamber 12 inner diameter is 5 mm. It is.
[0021]
The movable side sheet member 18 is assembled to the rod-shaped movable member 20 so as to be rotatable. In other words, the cylindrical protrusion 42 is disposed at the tip of the rod-shaped movable member 20, and the inner diameter thereof is processed so that the clearance with the movable sheet member 18 is several μm. Further, a conical recess (not shown) is machined on the inner bottom surface of the cylindrical protrusion 42, and the spherical surface of the movable side sheet member 18 is in contact with the conical recess and does not jump out of the rod-shaped movable member 20. The cylindrical protrusion 42 is caulked with a predetermined caulking force that does not impair the rotational sliding property.
[0022]
Next, the operation of the first embodiment will be described.
The high-pressure fuel first passes through a fuel pipe (not shown) led out from the common rail, enters the high-pressure fuel introduction passage 9 of the accumulator fuel injection device 1, and the high-pressure fuel passages 10 on the control chamber 12 side and the injection nozzle 2 side respectively. It branches to 39 and is introduced. At this time, since the needle valve 4 of the injection nozzle 2 is biased in the valve closing direction by the spring member 6 attached to the nozzle pressure pin 5, no injection is performed. The electromagnetic two-way valve 17 is also kept closed by a spring member 16 that biases in the valve closing direction. In the above state, the pressure in the high pressure fuel introduction passage 9 gradually increases. The pressure increase rate immediately after the engine is started is about 25 to 30 MPa / sec. In addition to the spring member 6 attached to the nozzle pressure pin 5 biasing the needle valve 4 in the valve closing direction, the control piston 8 causes the needle valve 4 to close in the valve closing direction by the high pressure fuel entering the control chamber 12. Energize to. Accordingly, fuel is not injected from the injection nozzle 2 until the electromagnetic two-way valve 17 is opened. This is because there is a difference between the pressure receiving area of the control piston 8 and the pressure receiving area of the nozzle needle valve, and the former is larger.
[0023]
Further, the set load of the spring member 16 for urging the electromagnetic two-way valve 17 in the valve closing direction is set to 65 N, and it is opened when the maximum control chamber pressure is 150 MPa when the accumulator type fuel injection device 1 is used. Since it is set to be larger than the hydraulic load 20N in the valve direction, the valve is not opened by the hydraulic load in the same manner as the needle valve 4 of the injection nozzle 2.
[0024]
When the electromagnetic coil 15 is energized to open the electromagnetic two-way valve 17 in this state, the armature 21 is attracted by the electromagnetic force generated from the electromagnetic coil 15. The sum of the oil pressure acting in the valve opening direction generated by the electromagnetic force and the pressure in the control chamber 12 acting on the pressure receiving portion of the movable side sheet member 18 is determined by the set load of the spring member 16 biased in the valve closing direction. When it gets bigger, it opens. Since the electromagnetic force in the first embodiment is set to about 100 N, for example, if the maximum injection pressure is 150 MPa, the electromagnetic coil 15 must be electromagnetically energized unless the electromagnetic coil 15 is energized for valve opening as described above. The direction valve 17 is kept in a closed state. Once the electromagnetic coil 15 is energized, the electromagnetic two-way valve 17 is opened, and the fuel in the control chamber 12 flows out into the fuel low pressure chamber 11 through the second throttle hole 14, and push rod 33, armature 21. Then, it flows into a leak fuel recovery pipe (not shown) through the low pressure passages 34, 35, 36, 29 and the union 61 penetrating the electromagnetic coil 15. After the outflow of the high-pressure fuel from the control chamber 12 has started and for a while, the pressure in the control chamber 12 drops below half of the pressure in the high-pressure fuel introduction passage 9 and the injection nozzle fuel introduction passage 39. This is because the passage area of the first throttle hole 13 for regulating the fuel introduced into the control chamber 12 is compared with the passage area of the second throttle hole 14 for regulating fuel flowing out from the control chamber 12. This is because it is configured to be small. When the pressure in the control chamber 12 further decreases, the force relationship between the needle valve 4 of the injection nozzle 2, the hydraulic load of the control piston 8, and the set load of the spring member 6 is reversed, and the force in the valve opening direction wins, Fuel injection is started from the fuel injection hole 3 of the injection nozzle 2.
[0025]
When the above state continues and the injection end time comes, the energization of the electromagnetic coil 15 is cut off. At this time, since the electromagnetic force 100N for attracting the armature 21 becomes 0, the electromagnetic two-way valve 17 is closed by the force of the spring member 16 that urges the electromagnetic two-way valve 17 in the valve closing direction. Then, the high pressure fuel is introduced into the control chamber 12 via the high pressure fuel introduction passage 9 and the control chamber fuel introduction passage 10, and the pressure in the control chamber 12 gradually returns to the initial state before the electromagnetic two-way valve 17 is opened. Come. If the force relationship between the hydraulic load and the set load of the spring member 6 is reversed during the pressurization process of the control chamber 12, the needle valve 4 of the injection nozzle 2 is closed and the injection is terminated.
[0026]
In the accumulator type fuel injection device 1 that performs the above-described configuration and operation, the first throttle hole 13 for limiting the fuel introduced into the control chamber 12 located between the high-pressure fuel introduction passage 9 and the control chamber 12, and the control The second throttle hole 14 having a passage resistance smaller than that of the first throttle hole 13 located between the chamber 12 and the low pressure passages 34, 35, 36, 29 or the fuel low pressure chamber 11 is separately disposed (or integrally formed). Control chamber pressure setting members 51 and 52 and control chamber pressure setting members 51 and 52 fastened to the injector body 7 (or screw members fastened to the injector body 7) with screws or caulking. At least a part of the contact surface with the fixing member (cylinder) 19 is located in the contact surface 52 a of the control chamber pressure setting members 51 and 52 with the control chamber 12. That is, in the first embodiment, at least a part of the contact surface 19a of the second control chamber pressure setting member 51 and the cylinder 19 is more than the contact surface 52a of the first control chamber pressure setting member 52 with the control chamber 12a. Located inside.
[0027]
The effect of this configuration will be described.
For comparison with the first embodiment, a sectional view of the vicinity of the electromagnetic two-way valve 17 when the cylinder end surface 19a contacts only the outside of the contact surface 52a with the control chamber 12 of the first control chamber pressure setting member 52. Is shown in FIG. 4A is a side cross-sectional view along the central axis, FIG. 4B is a cross-sectional view taken along the line AA in FIG. 4A, and FIG. 4C is an explanatory view showing a deformed state of the first control chamber pressure setting member 52. FIG. Here, the surface of the cross-hatched portion shown on the AA cross section of FIGS. 3 and 4 is the operating position of the contact surface 19 a between the cylinder 19 and the second control chamber pressure setting member 51. The pressure acting on the contact surface 52a of the first control chamber pressure setting member 52 with the control chamber 12 reaches a maximum of 150 MPa when the electromagnetic two-way valve 17 is closed. This pressure is the first control chamber pressure setting member. An oil pressure of about 3 kN is generated by acting on the surface 52 a in contact with the control chamber 12 of 52. When the cylinder end surface 19a contacts only outside the contact surface 52a as shown in FIG. 4 (A), the first control chamber pressure setting member 52 is opposite to the control chamber 12 as shown in FIG. 4 (C). To form a minute gap between the injector body 7 and the injector body 7. The second control chamber pressure setting member 51 is formed by high-pressure fuel in the fuel introduction passage 55 that communicates the first throttle hole 13 disposed on the surface of the first control chamber pressure setting member 52 and the control chamber 12. It deforms in a convex shape in the opposite direction of the control chamber 12, and a minute gap is generated between the first control chamber pressure setting member 52 and the first control chamber pressure setting member 52. Due to these two minute gaps, the performance of the accumulator fuel injection device described below is deteriorated.
[0028]
First, both of the control chamber pressure setting members 51 and 52 are connected to the low pressure leak recovery passages 53 and 54 that communicate with the low pressure passage 31 opened in the valve side end surface 7a of the injector body 7 and the low pressure chamber 11 provided in the cylinder 19. When there is a minute gap due to the convex deformation, high-pressure fuel leaks from the minute gap, and the amount of fuel leakage of the accumulator fuel injection device increases.
[0029]
Second, if there is a minute gap due to the convex deformation of the first control chamber pressure setting member 52 up to the control chamber fuel introduction passage 10 opening in the valve side end surface 7a of the injector body 7, the first throttle hole 13 In addition to this, the high-pressure fuel flows into the control chamber 12 and the flow rate of the control chamber 12 increases. That is, since the pressure increase speed of the control chamber pressure is increased and the pressure decrease speed is decreased, the nozzle opening time is shortened and the injection amount is decreased.
[0030]
However, as shown in FIG. 3, the contact surface 19 a of the second control chamber pressure setting member 51 and the cylinder 19 is at least partially in the contact surface 52 a of the first control chamber pressure setting member 52 with the control chamber 12. In the case of the first embodiment, the axial force acting on the cylinder end surface 19a acts on the inner side of the pressure receiving surface 52a of the high pressure fuel in the control chamber 12, so that both the control chamber pressure setting members 51 and 52 are convex. Therefore, the minute gap can be prevented from reaching the low pressure leak recovery passages 53 and 54 and the control chamber fuel introduction passage 10. Accordingly, no fuel leak occurs between the first control chamber pressure setting member 52 and the injector body 7, so that the amount of leak of the accumulator fuel injection device can be reduced, and the control chamber 12 and the control chamber fuel introduction passage 10 communicate with each other. Therefore, it is possible to prevent a decrease in the injection amount.
[0031]
FIG. 5 shows the case where the cylinder end surface 19a of FIG. 4 contacts only the outer side of the contact surface 52a of the first control chamber pressure setting member 52 with the control chamber 12, and the case corresponding to the first embodiment of FIG. And FIG. 5 (a) and FIG. 5 (b) show how the fuel leak amount increase amount and the injection amount increase amount change with time, respectively. Increases when the first control chamber pressure setting member 52 contacts only outside the contact surface 52a with the control chamber 12 and when the first control chamber pressure setting member 52 corresponds to the first embodiment of FIG. The change with time is shown.
[0032]
As can be seen from FIG. 5, the leak amount of (a) in the former case increases rapidly from 300 to 400 hours, and the injection amount gradually decreases to 400 hours. This is because the micro-gap between the first control chamber pressure setting member 52 and the injector body 7 gradually increases due to the oil pressure in the control chamber 12 between 0 and 400 hours, and the control chamber fuel is introduced as the operation time elapses. It shows that the amount of injection decreased because the fuel flowing from the passage 10 into the control chamber 12 increased. That is, the first control chamber pressure setting member 52 is deformed into a convex shape, and the light oil penetrates into the minute gap formed between the first control chamber pressure setting member 52 and the injector body 7, so that the first control is performed. Since the pressure receiving area of the chamber pressure setting member 52 is further larger than before the convex deformation, the minute gap between the first control chamber pressure setting member 52 and the injector body 7 further increases as the operation time elapses. It is shown that. However, since the light oil that permeates the minute gap around 400 hours reaches the leak recovery passage 31, the pressure receiving area of the first control chamber pressure setting member 52 does not increase any more, and the growth of the minute gap stops. Accordingly, the amount of fuel flowing into the control chamber 12 does not increase, and the injection amount does not decrease.
[0033]
On the other hand, in the case of (b), which is the configuration of the first embodiment, even if the system is operated for a long time, the amount of fuel leakage hardly increases and the injection amount does not decrease. That is, a part of the contact surface 19a between the second control chamber pressure setting member 51 and the cylinder 19 is positioned within the contact surface 52a with the control chamber 12 of the first control chamber pressure setting member 52, whereby the first Since the control chamber pressure setting member can be prevented from being deformed in a convex shape, the pressure receiving area of the first control chamber pressure setting member 52 does not increase as the operation time elapses. Thus, with the configuration of the first embodiment, it is possible to reduce changes in the performance of the accumulator fuel injection device 1 over time, such as an increase in the fuel leak amount and a decrease in the injection amount.
[0034]
As described above, the accumulator type fuel injection device 1 adopting the present invention eliminates leakage of the high pressure seal surfaces of the two control chamber pressure setting members 51 and 52, and other than the first throttle hole 13 to the control chamber 12. Therefore, the amount of fuel leakage can be kept small, and a decrease in the injection amount due to the fuel inflow from other than the first throttle hole 13 to the control chamber 12 can be prevented. Furthermore, the above-described effect can be obtained even after long-time operation, and a highly reliable pressure-accumulation fuel injection device with little change in characteristics over time can be realized.
[0035]
Next, a second embodiment of the present invention will be described. FIG. 6 is a cross-sectional view of the detailed structure of the electromagnetic two-way valve used in the second embodiment of the present invention, (A) is a side cross-sectional view along the central axis, and (B) is A in (A). It is -A sectional drawing. Here, the surface of the cross-hatched portion shown in (B) in the A-A cross-sectional view of FIG. 6 is the operating position of the contact surface 19 a between the cylinder 19 and the second control chamber pressure setting member 51. .
[0036]
In the second embodiment, the contact surface 19a of the second control chamber pressure setting member 51 and the cylinder 19 has a shape located only within the contact surface 52a of the first control chamber pressure setting member 52 with the control chamber 12. The other structure is the same as that of the first embodiment.
Next, functions and effects of the second embodiment will be described. In the case of having the configuration of the second embodiment, since all of the axial force acting on the cylinder end surface 19a acts on the pressure receiving surface 52a of the high pressure fuel in the control chamber 12, both the control chamber pressure setting members 51 and 52 The convex deformation can be completely eliminated, and communication between the control chamber 12, the low pressure leak recovery passages 53 and 54, and the control chamber fuel introduction passage 10 can be prevented. In particular, in the first embodiment, at least a part of the contact surface 19a of the second control chamber pressure setting member 51 and the cylinder 19 is located inside the contact surface 52a of the first control chamber pressure setting member 52 with the control chamber 12. If the convex deformation of both the control chamber pressure setting members 51 and 52 cannot be prevented even if the form is used, it is effective to use the configuration of the second embodiment.
[0037]
As described above, by using the configuration of the second embodiment, the fuel leakage between the first control chamber pressure setting member 52 and the injector body 7 does not occur, and the leakage amount of the pressure accumulating fuel injection device can be reduced. At the same time, the control chamber 12 and the control chamber fuel introduction passage 10 do not communicate with each other, and a decrease in the injection amount can be prevented.
Next, a third embodiment of the present invention will be described. FIG. 7 is a cross-sectional view of the detailed structure of the electromagnetic two-way valve used in the third embodiment of the present invention, (A) is a side cross-sectional view along the central axis, and (B) is A in (A). It is -A sectional drawing. Here, the surface of the cross-hatched portion shown in (B) in the A-A cross-sectional view of FIG. 6 is the operating position of the contact surface 19 a between the cylinder 19 and the second control chamber pressure setting member 51. .
[0038]
In the third embodiment, the contact surface 19a of the second control chamber pressure setting member 51 and the cylinder 19 is continuous in the direction of rotation about the central axis of the control chamber 12, and the other structure is the first. This is the same as the embodiment. The control chamber pressure setting members 51 and 52 are both attached to the injector body 7 in a state of being positioned by two pins (not shown).
[0039]
Next, functions and effects of the third embodiment will be described. When the cylinder 19 and the injector body 7 have screw portions as in the configuration in FIG. 7 and the control chamber pressure setting members 51 and 52 are fixed by these fastening forces, the cylinder 19 and the second control chamber pressure setting are set. Friction resistance due to rotation of the cylinder 19 acts on the contact surface 19a of the member 51, and axial force that the cylinder 19 tries to suppress the second control chamber pressure setting member 51 decreases. Accordingly, the smaller the frictional resistance between the contact surface 19a of the cylinder 19 and the second control chamber pressure setting member 51, the greater the axial force that the cylinder 19 tries to suppress the second control chamber pressure setting member 51, and the control chamber pressure. The convex deformation of both the setting members 51 and 52 can be reduced, and the control chamber 12, the low pressure leak recovery passages 53 and 54, and the control chamber fuel introduction passage 10 can be prevented from communicating with each other.
[0040]
Therefore, in FIG. 7 having the configuration of the third embodiment, the contact surface 19a of the cylinder 19 and the second control chamber pressure setting member 51 has a discontinuous shape in a direction rotating around the central axis of the control chamber 12. In addition, since the frictional resistance between the contact surface 19a of the cylinder 19 and the second control chamber pressure setting member 51 can be reduced, the effect of preventing communication between the control chamber 12, the low pressure leak recovery passages 53 and 54, and the control chamber fuel introduction passage 10 can be prevented. Can be increased. In addition, the discontinuous shape in the direction in which the contact surface 19a of the cylinder 19 and the second control chamber pressure setting member 51 rotates around the central axis of the control chamber 12 is, for example, shown in FIGS. Thus, the contact surface 19a of the cylinder 19 and the second control chamber pressure setting member 51 has a groove, a hole, etc. in the radial direction of the control chamber 12 having a cylindrical shape, and the contact surface 19a is the center of the control chamber 12 This is a case where it is constituted by two surfaces divided by grooves, holes or the like that cross the direction of rotation about the axis.
[0041]
Next, a fourth embodiment of the present invention will be described. FIG. 8: is sectional drawing of the detailed structure of the electromagnetic two-way valve used for the 4th Embodiment of this invention, (A) is side sectional drawing along a central axis, (B) is in (A). It is AA sectional drawing. Here, the surface of the cross-hatched portion shown in (B) in the A-A cross-sectional view of FIG. 8 is the operating position of the oil pressure of the high-pressure fuel with respect to the second control chamber pressure setting member 51. In the fourth embodiment, since the first throttle hole 13 is disposed in the injector body 7, the first control chamber pressure setting member 52 does not exist, and the second control chamber pressure setting member 51 and the injector body are not present. 7 is a configuration in which there is no surface on which high-pressure fuel acts other than the contact surface 52a with the control chamber 12 opened in FIG. Other structures are the same as those in the first embodiment.
[0042]
Next, functions and effects of the fourth embodiment will be described. As shown in FIG. 3, when there are two of the first control chamber pressure setting member 52 and the second control chamber pressure setting member 51, the high-pressure fuel in the control chamber 12 is the control chamber 12 and the first control chamber pressure. It acts on the contact surface 52a with the setting member 52, the contact surface 55a with the high pressure passage 55 disposed between the first throttle hole 13 and the control chamber 12, and the second control chamber pressure setting member 51. Accordingly, the oil pressure acting on the two contact surfaces 52a and 55a acts as a force that deforms the first control chamber pressure setting member 52 and the second control chamber pressure setting member 51 in a convex shape. The convex deformation of the chamber pressure setting member 52 and the second control chamber pressure setting member 51 is reduced, so that the first control chamber pressure setting member 52 and the first control chamber pressure setting member 51 or the first control chamber are reduced. In order to prevent communication between the pressure setting member 52 and the injector body 7, it is necessary to make the areas of the contact surfaces 52a and 55a as small as possible. In the configuration of the fourth embodiment, the portion on which the high pressure fuel acts is only the contact surface 52a between the second control chamber pressure setting member 51 and the control chamber 12, and therefore the second control chamber pressure setting member 51 is convex. Therefore, the convex deformation of the second control chamber pressure setting member 51 can be reduced. Therefore, the amount of fuel leak from the control chamber 12 to the low pressure leak recovery passage 31 and the fuel inflow from the control chamber fuel introduction passage 10 to the control chamber 12 can be prevented.
[Brief description of the drawings]
FIG. 1 is an overall side cross-sectional view along a central axis of a pressure accumulating fuel injection device showing a first embodiment of the present invention.
FIG. 2 is a side cross-sectional view of a main part in FIG.
3A and 3B are detailed sectional views of the electromagnetic two-way valve used in the first embodiment of the present invention, in which FIG. 3A is a side sectional view along the central axis, and FIG. 3B is A in FIG. It is -A sectional drawing.
FIG. 4 shows the electromagnetic two-way when the cylinder end surface 19a contacts only the outside of the contact surface 52a of the first control chamber pressure setting member 52 with the control chamber 12 for comparison with the first embodiment. It is sectional drawing of the valve 17 vicinity, (A) is side surface sectional drawing along a central axis, (B) is AA sectional drawing in (A), (C) is the 1st control chamber pressure setting member 52. It is explanatory drawing which shows the deformation | transformation state.
5 corresponds to the case where the cylinder end surface 19a of FIG. 4 contacts only the outside of the contact surface 52a of the first control chamber pressure setting member 52 with the control chamber 12, and corresponds to the first embodiment of FIG. It is a graph which shows how the fuel leak amount increase amount and the injection amount increase amount each changed with time.
FIG. 6 is a cross-sectional view of a detailed structure of an electromagnetic two-way valve used in the second embodiment of the present invention, (A) is a side cross-sectional view along the central axis, and (B) is a cross-sectional view in (A). It is AA sectional drawing.
FIG. 7 is a cross-sectional view of a detailed structure of an electromagnetic two-way valve used in a third embodiment of the present invention, (A) is a side cross-sectional view along the central axis, and (B) is a cross-sectional view in (A). It is AA sectional drawing.
FIG. 8 is a cross-sectional view of a detailed structure of an electromagnetic two-way valve used in a fourth embodiment of the present invention, (A) is a side cross-sectional view along the central axis, and (B) is a cross-sectional view in (A). It is AA sectional drawing.
[Explanation of symbols]
1 Accumulated fuel injection system
2 Injection nozzle
3 Fuel injection holes
4 Needle valve
7 Injector body
8 Control piston
9 High-pressure fuel introduction passage
11 Fuel low pressure chamber
12 Control room
13 First aperture
14 Second aperture
15 Electromagnetic coil
16 Spring member
17 Electromagnetic two-way valve
19 Guide member, fixing member (cylinder)
20 Movable member (bar-shaped movable member)
29 Fuel Low Pressure Passage (Leakage Fuel Recovery Passage)
31 Low pressure leak recovery passage
34, 35, 36 Fuel low pressure passage
51 Second control chamber pressure setting member
52 1st control chamber pressure setting member

Claims

In the accumulator fuel injection device provided for each cylinder that receives fuel supply through a fuel pipe for deriving high pressure fuel from a common rail that accumulates high pressure fuel, and is electrically controlled to inject fuel into a diesel engine,
A needle valve for opening and closing a fuel injection hole of the injection nozzle, a control piston contacting or connecting to the needle valve, and high-pressure fuel injected from the fuel injection hole when the needle valve is opened, A high-pressure fuel introduction passage for leading to the fuel injection hole, and fuel that communicates with the high-pressure fuel introduction passage and urges the needle valve in the valve closing direction by oil pressure are stored in the fuel low-pressure passage or the fuel low-pressure chamber. A control chamber that communicates with the control piston is slidably fitted, and a low-pressure leak recovery passage that recovers low-pressure leak from the needle valve of the injection nozzle and the control piston and a high-pressure fuel introduction passage are provided. Having an injector body
A first throttle hole for limiting fuel introduced into the control chamber located between the high-pressure fuel introduction passage and the control chamber; and located between the control chamber and the fuel low-pressure passage or the fuel low-pressure chamber. A control chamber pressure setting member for disposing a second throttle hole having a passage resistance smaller than that of the first throttle hole;
Between the second throttle hole and the fuel low-pressure passage, an electromagnetic coil for opening or shutting off the high-pressure fuel in the control chamber, driven by an electromagnetic force generated from the electromagnetic coil, and in the valve closing direction An electromagnetic two-way valve having a spring member for urging the movable member, a movable member driven by the electromagnetic coil, and a guide member for slidably fitting the movable member;
The control chamber pressure setting member is in contact with the control chamber by a fixing member of the control chamber pressure setting member that is fastened to the injector body or a screw member fastened to the injector body with a screw or caulking. The control chamber pressure setting member located above is fixed by pressing in the injector body direction from the surface opposite to the surface in contact with the control chamber,
At least a part of the contact surface between the control chamber pressure setting member and the fixed member is located within the contact surface of the control chamber pressure setting member with the control chamber.

2. The contact surface of the control chamber pressure setting member and the fixing member has a shape positioned only inside the contact surface of the control chamber pressure setting member with the control chamber. Accumulated fuel injection system.

3. The pressure accumulation type according to claim 1, wherein a contact surface between the control chamber pressure setting member and the fixing member is continuous in a direction rotating around a central axis of the control chamber. Fuel injection device.

4. The control chamber pressure setting member has no surface on which high-pressure fuel acts other than a contact surface with the control chamber that is opened in the injector body. Accumulator fuel injection system.