JP3829605B2 - Fuel injection device - Google Patents

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Publication number
JP3829605B2
JP3829605B2 JP2000260889A JP2000260889A JP3829605B2 JP 3829605 B2 JP3829605 B2 JP 3829605B2 JP 2000260889 A JP2000260889 A JP 2000260889A JP 2000260889 A JP2000260889 A JP 2000260889A JP 3829605 B2 JP3829605 B2 JP 3829605B2
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Japan
Prior art keywords
pressure control
valve
control valve
lift amount
pressure
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JP2000260889A
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JP2002070682A (en
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義正 渡辺
和広 大前
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Toyota Motor Corp
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Toyota Motor Corp
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【０００１】
【発明の属する技術分野】
本発明は燃料噴射装置に関する。
【０００２】
【従来の技術】
従来、燃料噴射用噴孔を開閉する噴孔開閉弁と、噴孔開閉弁を開弁側に付勢する開弁側付勢手段と、噴孔開閉弁を閉弁側に付勢する閉弁側付勢手段とを具備する燃料噴射装置が知られている。この種の燃料噴射装置の例としては、例えば特開平８−３３４０７２号公報に記載されたものがある。特開平３−３３４０７２号公報に記載された燃料噴射装置では、開弁側付勢手段がノズルボディ内の燃料だまり室により形成され、閉弁側付勢手段がスプリングにより構成されている。
【０００３】
【発明が解決しようとする課題】
ところが、特開平８−３３４０７２号公報に記載された燃料噴射装置では、閉弁側付勢手段がスプリングにより構成されているため、噴孔開閉弁を全閉位置から全開位置と全閉位置との間の中間リフト位置まで移動させるためには、燃料だまり室内の圧力を増加させ、つまり、燃料供給圧を増加させ、噴孔開閉弁を開弁側に付勢する力が噴孔開閉弁を閉弁側に付勢する力よりも大きくなるようにしなければならない。また、噴孔開閉弁を中間リフト位置にほぼ停止させるためには、燃料だまり室内の圧力を調節し、噴孔開閉弁を開弁側に付勢する力と噴孔開閉弁を閉弁側に付勢する力とを釣り合わせなければならない。その上、噴孔開閉弁を所望の中間リフト位置にほぼ停止させるためには、その所望の中間リフト位置において噴孔開閉弁を開弁側に付勢する力と噴孔開閉弁を閉弁側に付勢する力とが釣り合うように、燃料だまり室内の圧力を微調節しなければならない。
【０００４】
前記問題点に鑑み、本発明は、燃料供給圧を増加させる必要なく噴孔開閉弁を全閉位置から中間リフト位置まで移動させることができると共に、燃料供給圧を微調節する必要なく噴孔開閉弁を所望の中間リフト位置にほぼ停止させることができる燃料噴射装置、つまり、燃料噴射率波形を所望の燃料噴射率波形に切り換えることができる燃料噴射装置を提供することを目的とする。
【０００５】
【課題を解決するための手段】
請求項１に記載の発明によれば、燃料噴射用噴孔を開閉する噴孔開閉弁と、前記噴孔開閉弁を開弁側に付勢する開弁側付勢手段と、前記噴孔開閉弁を閉弁側に付勢する閉弁側付勢手段とを具備する燃料噴射装置において、前記閉弁側付勢手段が圧力制御室を有し、前記圧力制御室内の圧力を制御するための圧力制御弁を圧力制御弁室内に配置し、高圧燃料供給通路と前記圧力制御弁室とを第一通路によって連通し、前記圧力制御弁室と前記圧力制御室とを第二通路によって連通し、前記圧力制御弁を第一の位置に配置した第一モード時に、前記圧力制御弁室から低圧燃料リーク通路への燃料の流れが遮断されることにより、前記高圧燃料供給通路内の燃料が前記第一通路及び前記第二通路を介して前記圧力制御室内に供給されて前記圧力制御室内の圧力が上昇せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも大きくなって前記噴孔開閉弁が全閉位置に向かって移動せしめられ、前記圧力制御弁を第二の位置に配置した第二モード時に、前記圧力制御室から前記圧力制御弁室への燃料の流れが許容され、かつ、前記圧力制御弁室から前記低圧燃料リーク通路への燃料の流れが許容されることにより、前記圧力制御室内の燃料が前記第二通路及び前記圧力制御弁室を介して前記低圧燃料リーク通路内に排出されて前記圧力制御室内の圧力が低下せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも小さくなって前記噴孔開閉弁が全開位置に向かって移動せしめられ、前記圧力制御弁を第三の位置に配置した第三モード時に、前記圧力制御室と前記圧力制御弁室との間の燃料の流れが遮断されて前記圧力制御室が密閉され、その密閉された圧力制御室によって前記噴孔開閉弁がホールドされることにより、前記噴孔開閉弁が全開位置と全閉位置との間の任意のリフト位置にほぼ停止せしめられるようにし、前記第一モード時には圧力制御弁リフト量がゼロになっており、前記第三モード時には圧力制御弁リフト量が最大値になっており、前記第二モード時には圧力制御弁リフト量がそれらの間の値になっており、前記噴孔開閉弁を全閉位置から所定の中間リフト位置まで移動させることが要求されるとき、圧力制御弁リフト量をゼロから増加させて前記噴孔開閉弁の移動を開始させると共に、前記噴孔開閉弁が前記所定の中間リフト位置まで移動する前に圧力制御弁リフト量が最大値まで増加してしまわないように圧力制御弁リフト量の増加速度を設定し、次いで前記噴孔開閉弁が前記所定の中間リフト位置まで移動した時に圧力制御弁リフト量を最大値に固定することにより、前記噴孔開閉弁を前記所定の中間リフト位置にほぼ停止させるようにした燃料噴射装置が提供される。
【０００６】
請求項１に記載の燃料噴射装置では、閉弁側付勢手段が圧力制御室を有し、圧力制御室内の圧力が圧力制御弁によって制御される。そのため、圧力制御弁を第一の位置又は第二の位置に配置し、圧力制御室内の圧力を増減させることにより、噴孔開閉弁を閉弁側に付勢する力を増減させることができる。それゆえ、高圧燃料供給通路内の圧力を増加させなくても、圧力制御弁を第二の位置に配置し、圧力制御室内の圧力を減少させて噴孔開閉弁を閉弁側に付勢する力を減少させることにより、噴孔開閉弁を全閉位置から中間リフト位置まで移動させることができる。更に請求項１に記載の燃料噴射装置では、圧力制御弁を第三の位置に配置した時に、圧力制御室を圧力制御弁により密閉することができる。そのため、その密閉された圧力制御室によって噴孔開閉弁をホールドすることができる。それゆえ、高圧燃料供給通路内の圧力を微調節しなくても、噴孔開閉弁を全開位置と全閉位置との間の任意の所望のリフト位置にほぼ停止させることができる。つまり、噴孔開閉弁を所望の中間リフト位置まで移動させ、そこにほぼ停止させることにより、燃料噴射率波形を所望の燃料噴射率波形に切り換えることができる。
【００１０】
請求項１に記載の燃料噴射装置では、噴孔開閉弁を全閉位置から所定の中間リフト位置まで移動させるとき、噴孔開閉弁がその所定の中間リフト位置まで移動する前に圧力制御弁リフト量が最大値まで増加してしまわないように圧力制御弁リフト量の増加速度が設定される。そのため、噴孔開閉弁を全閉位置から所定の中間リフト位置まで移動させている途中に、圧力制御弁リフト量が最大値まで増加してしまうのに伴って第二モードから第三モードに切り換わって噴孔開閉弁が停止せしめられてしまい、その結果、噴孔開閉弁がその所定の中間リフト位置までリフトできなくなってしまうのを回避することができる。
【００１３】
請求項２に記載の発明によれば、前記噴孔開閉弁を全閉位置から所定の中間リフト位置まで移動させ、次いで全開位置まで移動させることが要求されるとき、圧力制御弁リフト量をゼロから増加させて前記噴孔開閉弁の移動を開始させると共に、前記噴孔開閉弁が前記所定の中間リフト位置まで移動する前に圧力制御弁リフト量が最大値まで増加してしまわないように圧力制御弁リフト量の増加速度を設定し、次いで前記噴孔開閉弁が前記所定の中間リフト位置まで移動した時に圧力制御弁リフト量を最大値に固定することにより、前記噴孔開閉弁を前記所定の中間リフト位置にほぼ停止させ、次いで圧力制御弁リフト量を最大値から減少させて前記噴孔開閉弁を全開位置に向かって再び移動させると共に、前記噴孔開閉弁が全開位置まで移動する前に圧力制御弁リフト量がゼロまで減少してしまわないように圧力制御弁リフト量の減少速度を設定し、前記噴孔開閉弁を全開位置まで移動させるようにした請求項１に記載の燃料噴射装置が提供される。
【００１４】
請求項２に記載の燃料噴射装置では、噴孔開閉弁を中間リフト位置から全開位置まで移動させるとき、噴孔開閉弁が全開位置まで移動する前に圧力制御弁リフト量がゼロまで減少してしまわないように圧力制御弁リフト量の減少速度が設定される。そのため、噴孔開閉弁を中間リフト位置から全開位置まで移動させている途中に、圧力制御弁リフト量がゼロまで減少してしまうのに伴って第二モードから第一モードに切り換わって噴孔開閉弁が全閉位置に向かって移動し始めてしまい、その結果、噴孔開閉弁が全開位置までリフトできなくなってしまうのを回避することができる。
【００１９】
請求項３に記載の発明によれば、圧力制御弁リフト量の増加速度又は圧力制御弁リフト量の減少速度を前記高圧燃料供給通路内の圧力と燃料温度とに基づいて算出するようにした請求項１又は２に記載の燃料噴射装置が提供される。
【００２０】
請求項３に記載の燃料噴射装置では、圧力制御弁リフト量に応じて変化する圧力制御室内の圧力が、更に高圧燃料供給通路内の圧力及び燃料温度にも応じて変化してしまうことに鑑み、圧力制御室内の圧力を要求通りに制御するために、圧力制御弁リフト量の増加速度又は圧力制御弁リフト量の減少速度が高圧燃料供給通路内の圧力と燃料温度とに基づいて制御される。そのため、圧力制御室内の圧力を要求通りに制御することができる。
【００２１】
請求項４に記載の発明によれば、前記第一通路の絞り部の絞り程度に基づいて圧力制御弁リフト量の増加速度又は圧力制御弁リフト量の減少速度を設定するようにした請求項３に記載の燃料噴射装置が提供される。
【００２２】
請求項４に記載の燃料噴射装置では、圧力制御弁リフト量に応じて変化する圧力制御室内の圧力が、更に第一通路を通過する燃料流量にも応じて変化してしまうことに鑑み、圧力制御室内の圧力を要求通りに制御するために、圧力制御弁リフト量の増加速度又は圧力制御弁リフト量の減少速度が第一通路の絞り部の絞り程度に基づいて設定される。そのため、このような設定を行わない場合よりも正確に、圧力制御室内の圧力を要求通りに制御することができる。
【００２３】
請求項５に記載の発明によれば、噴孔開閉弁リフト量を検出するためのリフト量検出手段を設け、前記噴孔開閉弁が前記所定の中間リフト位置まで移動せしめられた時の実際の噴孔開閉弁リフト量とその時の要求噴孔開閉弁リフト量との差分に基づいて、圧力制御弁リフト量を固定する期間、圧力制御弁リフト量の増加速度、又は圧力制御弁リフト量の減少速度をフィードバック補正するようにした請求項３又は４に記載の燃料噴射装置が提供される。
【００２４】
請求項５に記載の燃料噴射装置では、噴孔開閉弁が所定の中間リフト位置まで移動せしめられた時の実際の噴孔開閉弁リフト量とその時の要求噴孔開閉弁リフト量との差分に基づいて、圧力制御弁リフト量を固定する期間、圧力制御弁リフト量の増加速度、又は圧力制御弁リフト量の減少速度がフィードバック補正される。そのため、フィードバック補正が行われない場合よりも正確に、噴孔開閉弁リフト量を要求通りに制御することができる。
【００２５】
請求項６に記載の発明によれば、燃料噴射用噴孔を開閉する噴孔開閉弁と、前記噴孔開閉弁を開弁側に付勢する開弁側付勢手段と、前記噴孔開閉弁を閉弁側に付勢する閉弁側付勢手段とを具備する燃料噴射装置において、前記閉弁側付勢手段が圧力制御室を有し、前記圧力制御室内の圧力を制御するための圧力制御弁を圧力制御弁室内に配置し、高圧燃料供給通路と前記圧力制御弁室とを第一通路によって連通し、前記圧力制御弁室と前記圧力制御室とを第二通路によって連通し、前記圧力制御弁を第一の位置に配置した第一モード時に、前記圧力制御弁室から低圧燃料リーク通路への燃料の流れが遮断されることにより、前記高圧燃料供給通路内の燃料が前記第一通路及び前記第二通路を介して前記圧力制御室内に供給されて前記圧力制御室内の圧力が上昇せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも大きくなって前記噴孔開閉弁が全閉位置に向かって移動せしめられ、前記圧力制御弁を第二の位置に配置した第二モード時に、前記圧力制御室から前記圧力制御弁室への燃料の流れが許容され、かつ、前記圧力制御弁室から前記低圧燃料リーク通路への燃料の流れが許容されることにより、前記圧力制御室内の燃料が前記第二通路及び前記圧力制御弁室を介して前記低圧燃料リーク通路内に排出されて前記圧力制御室内の圧力が低下せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも小さくなって前記噴孔開閉弁が全開位置に向かって移動せしめられ、前記圧力制御弁を第三の位置に配置した第三モード時に、前記圧力制御室と前記圧力制御弁室との間の燃料の流れが遮断されて前記圧力制御室が密閉され、その密閉された圧力制御室によって前記噴孔開閉弁がホールドされることにより、前記噴孔開閉弁が全開位置と全閉位置との間の任意のリフト位置にほぼ停止せしめられるようにし、圧力制御弁リフト量が第二モード時及び第三モード時の圧力制御弁リフト量よりも小さくなっている第四の位置に前記圧力制御弁を配置した第四モード時に、前記噴孔開閉弁を閉弁側に付勢する力と前記噴孔開閉弁を開弁側に付勢する力とが等しくなるようにし、前記噴孔開閉弁が全開位置に位置している時に前記圧力制御弁を第四の位置に配置するようにした燃料噴射装置が提供される。
【００２６】
請求項６に記載の燃料噴射装置では、噴孔開閉弁が全開位置に位置している時に、圧力制御弁リフト量が第二モード時及び第三モード時の圧力制御弁リフト量よりも小さくなっている第四の位置に圧力制御弁が配置される。そのため、噴孔開閉弁が全開位置に位置している時に圧力制御弁が第二の位置に配置される場合や第三の位置に配置される場合に比べ、低圧燃料リーク通路内に排出される燃料量を低減することができる。それゆえ、高圧燃料が低圧燃料リーク通路内に排出されるのに伴って燃料温度が上昇してしまうのを抑制することができる。
【００２７】
請求項７に記載の発明によれば、噴孔開閉弁リフト量を検出するためのリフト量検出手段を設け、前記噴孔開閉弁が全開位置まで移動したら即座に前記圧力制御弁を第二の位置から第四の位置まで移動させるようにした請求項６に記載の燃料噴射装置が提供される。
【００２８】
請求項７に記載の燃料噴射装置では、噴孔開閉弁が全開位置まで移動したら即座に圧力制御弁が第二の位置から第四の位置まで移動せしめられる。そのため、低圧燃料リーク通路内に排出される燃料量を最小にすることができる。
【００３３】
【発明の実施の形態】
以下、添付図面を用いて本発明の実施形態について説明する。
【００３４】
図１は本発明の燃料噴射装置の第一の実施形態の概略断面図、図２は図１の一部を拡大した拡大図である。図１及び図２において、１は燃料噴射用噴孔、２は燃料噴射用噴孔１を開閉するニードル弁、３はニードル弁２を開弁側（図１及び図２の上側）に付勢する燃料だまり室、４はニードル弁２を閉弁側（図１及び図２の下側）に付勢する圧力制御室である。５はニードル弁２を閉弁側（図１及び図２の下側）に付勢するためのスプリング、６は圧力制御室４内の圧力を制御するための圧力制御弁、７は圧力制御弁６が内部に配置されている圧力制御弁室である。８は高圧燃料供給通路、９は高圧燃料供給通路８と圧力制御弁室７とを連通する第一通路、１０は第一通路９に形成された絞り部である。１１は圧力制御弁室７と圧力制御室４とを連通する第二通路、１２は第二通路１１に形成された絞り部、１３は低圧燃料リーク通路である。１４は圧力制御弁６を駆動するためのピエゾ式アクチュエータ、１５は圧力制御弁６とピエゾ式アクチュエータ１４との間に配置された作動油である。詳細には、燃料噴射用噴孔１から噴射されなかった燃料が作動油１５として使用される。１５は圧力制御弁６が全閉時に着座するシート部、１６は圧力制御弁６を閉弁側（図１及び図２の上側）に付勢するためのスプリングである。
【００３５】
図３は圧力制御弁の第一モード及び第二モードを示した図である。詳細には、図３（Ａ）は圧力制御弁６が全閉位置（第一の位置）に配置された第一モードを示しており、図３（Ｂ）は圧力制御弁６が中間リフト位置（第二の位置）に配置された第二モードを示している。図３（Ａ）に示すように、圧力制御弁６が全閉せしめられる時（圧力制御弁リフト量＝ゼロ）、圧力制御弁室７から低圧燃料リーク通路１３への燃料の流れが遮断されることにより、高圧燃料供給通路８内の燃料が第一通路９及び第二通路１１を介して圧力制御室４内に供給されて圧力制御室４内の圧力が上昇せしめられる。そのため、ニードル弁２を閉弁側（図１及び図２の下側）に付勢する圧力制御室４内の油圧（燃料圧）とスプリング５のばね圧との和が、ニードル弁２を開弁側（図１及び図２の上側）に付勢する燃料だまり室３内の油圧よりも大きくなり、その結果、ニードル弁２が閉弁側に移動せしめられるか、全閉位置に維持される。つまり、圧力制御弁６が全閉され続けると、ニードル弁２は全閉せしめられる。
【００３６】
一方、図３（Ｂ）に示すように、圧力制御弁６が中間リフト位置（第二の位置）に配置される時（圧力制御弁リフト量＝Ｌ２）、圧力制御室４から圧力制御弁室７への燃料の流れが許容され、かつ、圧力制御弁室７から低圧燃料リーク通路１３への燃料の流れが許容されることにより、圧力制御室４内の燃料が第二通路１１及び圧力制御弁室７を介して低圧燃料リーク通路１３内に排出されて圧力制御室４内の圧力が低下せしめられる。そのため、ニードル弁２を閉弁側（図１及び図２の下側）に付勢する圧力制御室４内の油圧（燃料圧）とスプリング８のばね圧との和が、ニードル弁２を開弁側（図１及び図２の上側）に付勢する燃料だまり室３内の油圧よりも小さくなり、その結果、ニードル弁２が開弁側に移動せしめられるか、全開位置に維持される。つまり、圧力制御弁６が中間リフト位置に維持されると、ニードル弁２は全開せしめられる。
【００３７】
図４は圧力制御弁の第三モード及び第四モードを示した図である。詳細には、図４（Ａ）は圧力制御弁６が全開位置（第三の位置）に配置された第三モードを示しており、図４（Ｂ）は第二モード（図３（Ｂ））時の圧力制御弁リフト量Ｌ２よりも圧力制御弁リフト量が小さい第四の位置に圧力制御弁６が配置された第四モードを示している。図４（Ａ）に示すように、圧力制御弁６が全開せしめられる時（圧力制御弁リフト量＝Ｌ３＝Ｌｍａｘ）、圧力制御室４と圧力制御弁室７との間の燃料の流れが遮断されて圧力制御室４が密閉され、その密閉された圧力制御室４によってニードル弁２がホールドされることにより、ニードル弁２が全開位置と全閉位置との間の任意のリフト位置にほぼ停止せしめられる。
【００３８】
図４（Ｂ）に示すように、圧力制御弁６が第四の位置に配置される時（圧力制御弁リフト量＝Ｌ４）、高圧燃料供給通路８内の燃料が第一通路９及び第二通路１１を介して圧力制御室４内に供給されると共に、圧力制御室４内の燃料が第二通路１１及び圧力制御弁室７を介して低圧燃料リーク通路１３内に排出される。そのため、ニードル弁２を閉弁側（図１及び図２の下側）に付勢する圧力制御室４内の油圧（燃料圧）とスプリング８のばね圧との和が、ニードル弁２を開弁側（図１及び図２の上側）に付勢する燃料だまり室３内の油圧と等しくなり、その結果、ニードル弁２が全開位置と全閉位置との間の任意のリフト位置にほぼ停止せしめられる。
【００３９】
図５はニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行するための圧力制御弁制御方法を示した図である。図５に示すように、燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）を実行するためにニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させることが要求されると（時間Ｔ１）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が開始され、圧力制御弁リフト量がゼロから増加せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ４よりも大きくなると）（時間Ｔ２）、ニードル弁２は開弁側に移動し始める。
【００４０】
次いで、ニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に向かって移動させ続けるために、圧力制御弁リフト量がＬ２のまま固定される（時間Ｔ２〜時間Ｔ３）。次いでニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止させるために圧力制御弁リフト量を再び増加させることが必要になった時（時間Ｔ３）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が再び開始され、圧力制御弁リフト量が再び増加せしめられる。圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になった時（時間Ｔ４）にニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に到達するように、時間Ｔ３は設定されている。
【００４１】
次いで、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止せしめられる。また、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が停止される。次いで、燃料噴射を終了するためにニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全閉位置まで移動させることが要求されると（時間Ｔ５）、ピエゾ式アクチュエータ１４に対する印加電圧の減少が開始され、圧力制御弁リフト量がゼロまで減少せしめられる。
【００４２】
図６は燃料噴射期間初期にニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行し、残りの燃料噴射期間中にニードル弁を全開位置に配置して燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。図６に示すように、燃料噴射期間初期に燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）を実行するためにニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させることが要求されると（時間Ｔ１）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が開始され、圧力制御弁リフト量がゼロから増加せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ４よりも大きくなると）（時間Ｔ２）、ニードル弁２は開弁側に移動し始める。
【００４３】
次いで、ニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に向かって移動させ続けるために、圧力制御弁リフト量がＬ２のまま固定される（時間Ｔ２〜時間Ｔ３）。次いでニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止させるために圧力制御弁リフト量を再び増加させることが必要になった時（時間Ｔ３）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が再び開始され、圧力制御弁リフト量が再び増加せしめられる。圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になった時（時間Ｔ４）にニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に到達するように、時間Ｔ３は設定されている。次いで、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止せしめられ、燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）が実行される。また、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が停止される。
【００４４】
次いで、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）を実行するためにニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させることが要求されると（時間Ｔ６）、ピエゾ式アクチュエータ１４に対する印加電圧の減少が開始され、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）から減少せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）よりも小さくなると）（時間Ｔ６以降）、ニードル弁２は開弁側に再び移動し始める。
【００４５】
次いで、ニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に向かって移動させ続けるために、圧力制御弁リフト量がＬ２のまま固定される（時間Ｔ７〜時間Ｔ８）。ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に突き当たると、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）が実行されることになる。次いで、燃料噴射を終了するためにニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）から全閉位置まで移動させることが要求されると（時間Ｔ８）、ピエゾ式アクチュエータ１４に対する印加電圧の減少が再び開始され、圧力制御弁リフト量がゼロまで減少せしめられる。次いで、圧力制御弁リフト量がゼロまで減少すると（時間Ｔ９）、ニードル弁２が全閉位置に向かって移動し始める。ニードル弁２が全閉位置に向かって移動し始めるべき時（時間Ｔ９）に圧力制御弁リフト量がゼロになるように、時間Ｔ８は設定されている。
【００４６】
図７は燃料噴射期間初期から燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。図７に示すように、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）を実行するためにニードル弁２を全閉位置から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させることが要求されると（時間Ｔ１）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が開始され、圧力制御弁リフト量がゼロから増加せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ４よりも大きくなると）（時間Ｔ２）、ニードル弁２は開弁側に移動し始める。
【００４７】
次いで、ニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に向かって移動させ続けるために、圧力制御弁リフト量がＬ２のまま固定される（時間Ｔ２〜時間Ｔ８）。ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に突き当たると、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）が実行されることになる。次いで、燃料噴射を終了するためにニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）から全閉位置まで移動させることが要求されると（時間Ｔ８）、ピエゾ式アクチュエータ１４に対する印加電圧の減少が再び開始され、圧力制御弁リフト量がゼロまで減少せしめられる。次いで、圧力制御弁リフト量がゼロまで減少すると（時間Ｔ９）、ニードル弁２が全閉位置に向かって移動し始める。ニードル弁２が全閉位置に向かって移動し始めるべき時（時間Ｔ９）に圧力制御弁リフト量がゼロになるように、時間Ｔ８は設定されている。
【００４８】
上述したように、圧力制御弁リフト量をＬ２に固定している期間中（図５の時間Ｔ２〜時間Ｔ３、図６の時間Ｔ２〜時間Ｔ３、時間Ｔ７〜時間Ｔ８）、圧力制御室４から圧力制御弁室７への燃料の流れが許容され、かつ、圧力制御弁室７から低圧燃料リーク通路１３への燃料の流れが許容されることにより、圧力制御室４内の燃料が第二通路１１及び圧力制御弁室７を介して低圧燃料リーク通路１３内に排出されて圧力制御室４内の圧力が低下せしめられる。そのため、ニードル弁２を閉弁側（図１及び図２の下側）に付勢する圧力制御室４内の油圧（燃料圧）とスプリング８のばね圧との和が、ニードル弁２を開弁側（図１及び図２の上側）に付勢する燃料だまり室３内の油圧よりも小さくなり、その結果、ニードル弁２が開弁側に移動せしめられる。
【００４９】
一方で、高圧燃料供給通路８内の圧力が低い場合には、第一通路９を介して圧力制御弁室７内に流入する燃料量が減少するのに伴って圧力制御弁室７内の圧力の減少が早まり、その結果、圧力制御室４内の圧力の減少が早まり、ニードル弁２のリフト速度が増加する。また、燃料温度が低い場合には、燃料の粘性が高くなるのに伴って第一通路９を介して圧力制御弁室７内に流入する燃料量が減少し、圧力制御弁室７内の圧力の減少が早まり、その結果、圧力制御室４内の圧力の減少が早まり、ニードル弁２のリフト速度が増加する。本実施形態ではこれらの事項に鑑み、圧力制御弁リフト量をＬ２に固定する期間（図５の時間Ｔ２〜時間Ｔ３、図６の時間Ｔ２〜時間Ｔ３、時間Ｔ７〜時間Ｔ８）が設定される。詳細には、高圧燃料供給通路８内の圧力が低い場合、ニードル弁２のリフト速度が増加することを考慮し、圧力制御弁リフト量をＬ２に固定する期間が短くされる。また、燃料温度が低い場合、ニードル弁２のリフト速度が増加することを考慮し、圧力制御弁リフト量をＬ２に固定する期間が短くされる。
【００５０】
更に、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも強い場合には、第一通路９を介して圧力制御弁室７内に流入する燃料量が減少するのに伴って圧力制御弁室７内の圧力の減少が早まり、その結果、圧力制御室４内の圧力の減少が早まり、ニードル弁２のリフト速度が増加する。一方、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも弱い場合には、第一通路９を介して圧力制御弁室７内に流入する燃料量が増加するのに伴って圧力制御弁室７内の圧力の低下が遅れ、その結果、圧力制御室４内の圧力の低下が遅れ、ニードル弁２のリフト速度が減少する。本実施形態ではこれらの事項に鑑み、圧力制御弁リフト量をＬ２に固定する期間（図５の時間Ｔ２〜時間Ｔ３、図６の時間Ｔ２〜時間Ｔ３、時間Ｔ７〜時間Ｔ８）が、燃料噴射装置の評価段階で補正される。詳細には、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも強い場合、ニードル弁２のリフト速度が増加することを考慮し、圧力制御弁リフト量をＬ２に固定する期間が短くされる。一方、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも弱い場合、ニードル弁２のリフト速度が減少することを考慮し、圧力制御弁リフト量をＬ２に固定する期間が長くされる。
【００５１】
本実施形態では、ニードル弁リフト量を検出するためのリフト量センサ（図示せず）が設けられている。そのリフト量センサにより、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝Ｌ２）まで移動せしめられ、そこにほぼ停止せしめられた時（図５の時間Ｔ４〜時間Ｔ５、図６の時間Ｔ４〜時間Ｔ６）の実際のニードル弁リフト量が検出され、その値とその時の要求ニードル弁リフト量（＝ＮＬｌｏｗ）との差分に基づいて圧力制御弁リフト量をＬ２に固定する期間（図５、図６の時間Ｔ２〜時間Ｔ３）がフィードバック補正される。詳細には、検出された実際のニードル弁リフト量が要求ニードル弁リフト量（＝ＮＬｌｏｗ）よりも小さい場合には、圧力制御弁リフト量をＬ２に固定する期間（図５、図６の時間Ｔ２〜時間Ｔ３）が長くされる。一方、検出された実際のニードル弁リフト量が要求ニードル弁リフト量（＝ＮＬｌｏｗ）よりも大きい場合には、圧力制御弁リフト量をＬ２に固定する期間（図５、図６の時間Ｔ２〜時間Ｔ３）が短くされる。このフィードバック補正は、ニードル弁２を中間リフト位置まで移動せしめる毎に実行してもよく、あるいは、所定の時間間隔をおいて定期的に実行してもよい。
【００５２】
本実施形態によれば、ニードル弁２を閉弁側（図１及び図２の下側）に付勢する圧力制御室４内の圧力が圧力制御弁６によって制御される。そのため、圧力制御弁を第一の位置（図３（Ａ））又は第二の位置（図３（Ｂ））に配置し、圧力制御室４内の圧力を増減させることにより、ニードル弁２を閉弁側（図１及び図２の下側）に付勢する力を増減させることができる。それゆえ、高圧燃料供給通路８内の圧力を増加させなくても、圧力制御弁６を第二の位置（図３（Ｂ））に配置し、圧力制御室４内の圧力を減少させてニードル弁２を閉弁側（図１及び図２の下側）に付勢する力を減少させることにより、ニードル弁２を全閉位置から中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させることができる。
【００５３】
更に本実施形態によれば、圧力制御弁を第三の位置（図４（Ａ））に配置した時に、圧力制御室４を圧力制御弁６により密閉することができる。そのため、その密閉された圧力制御室４によってニードル弁２をホールドすることができる。それゆえ、高圧燃料供給通路８内の圧力を微調節しなくても、ニードル弁２を全開位置と全閉位置との間の任意の所望のリフト位置にほぼ停止させることができる。つまり、ニードル弁２を所望の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させ、そこにほぼ停止させることにより、燃料噴射率を所望の燃料噴射率に切り換えることができる。
【００５４】
また本実施形態によれば、図５に示したように、ニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させるとき、ニードル弁２をその所定の中間リフト位置に向かって移動させ続けるために圧力制御弁リフト量が最大値Ｌｍａｘ（＝Ｌ３）よりも小さい所定値Ｌ２に固定される（時間Ｔ２〜時間Ｔ３）。そのため、ニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させている途中（時間Ｔ１〜時間Ｔ４）に、圧力制御弁リフト量が最大値Ｌｍａｘ（＝Ｌ３）まで増加してしまうのに伴って第二モード（図３（Ｂ））から第三モード（図４（Ａ））に切り換わってニードル弁２が停止せしめられてしまい、その結果、ニードル弁２がその所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）までリフトできなくなってしまうのを回避することができる。
【００５５】
更に本実施形態によれば、図６に示したように、ニードル弁２を中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させるとき、ニードル弁２を全開位置に向かって移動させ続けるために圧力制御弁リフト量がゼロよりも大きい所定値Ｌ２に固定される（時間Ｔ７〜時間Ｔ８）。そのため、ニードル弁２を中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させている途中（時間Ｔ６〜時間Ｔ９）に、圧力制御弁リフト量がゼロまで減少してしまうのに伴って第二モード（図３（Ｂ））から第一モード（図３（Ａ））に切り換わってニードル弁２が全閉位置に向かって移動し始めてしまい、その結果、ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）までリフトできなくなってしまうのを回避することができる。
【００５６】
更に本実施形態によれば、圧力制御弁リフト量に応じて変化する圧力制御室４内の圧力が、更に高圧燃料供給通路８内の圧力及び燃料温度にも応じて変化してしまうことに鑑み、圧力制御室４内の圧力を要求通りに制御するために、圧力制御弁リフト量を固定する期間（図５の時間Ｔ２〜時間Ｔ３、図６の時間Ｔ２〜時間Ｔ３、時間Ｔ７〜時間Ｔ８）が高圧燃料供給通路８内の圧力と燃料温度とに基づいて制御される。そのため、圧力制御室４内の圧力を要求通りに制御することができる。
【００５７】
更に本実施形態によれば、圧力制御弁リフト量に応じて変化する圧力制御室４内の圧力が、更に第一通路９を通過する燃料流量にも応じて変化してしまうことに鑑み、圧力制御室４内の圧力を要求通りに制御するために、圧力制御弁リフト量を固定する期間（図５の時間Ｔ２〜時間Ｔ３、図６の時間Ｔ２〜時間Ｔ３、時間Ｔ７〜時間Ｔ８）が第一通路９を通過する燃料流量に基づいて補正される。そのため、補正を行わない場合よりも正確に、圧力制御室４内の圧力を要求通りに制御することができる。
【００５８】
更に本実施形態によれば、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動せしめられた時の実際のニードル弁リフト量とその時の要求ニードル弁リフト量ＮＬｌｏｗとの差分に基づいて、圧力制御弁リフト量を固定する期間（図５の時間Ｔ２〜時間Ｔ３、図６の時間Ｔ２〜時間Ｔ３）がフィードバック補正される。そのため、フィードバック補正が行われない場合よりも正確に、ニードル弁リフト量を要求通りに制御することができる。
【００５９】
以下、本発明の燃料噴射装置の第二の実施形態について説明する。本実施形態の構成は、後述する点を除いて上述した第一の実施形態の構成と同様である。従って、後述する点を除いて第一の実施形態と同様の効果を奏することができる。
【００６０】
図８はニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行するための圧力制御弁制御方法を示した図である。図８に示すように、燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）を実行するためにニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させることが要求されると（時間Ｔ１）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が開始され、圧力制御弁リフト量がゼロから増加せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ４よりも大きくなると）、ニードル弁２は開弁側に移動し始める。
【００６１】
その場合、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動する前に圧力制御弁リフト量が最大値Ｌｍａｘ（＝Ｌ３）まで増加してしまわないように圧力制御弁リフト量の増加速度は比較的低速に設定されている（時間Ｔ１〜時間Ｔ４）。つまり、ピエゾ式アクチュエータ１４に対する印加電圧の増加速度が比較的低速に設定されている。詳細には、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になった時（時間Ｔ４）にニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に到達するように、圧力制御弁リフト量の増加速度は設定されている。
【００６２】
次いで、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止せしめられる。また、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が停止される。次いで、燃料噴射を終了するためにニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全閉位置まで移動させることが要求されると（時間Ｔ５）、ピエゾ式アクチュエータ１４に対する印加電圧の減少が開始され、圧力制御弁リフト量がゼロまで減少せしめられる。
【００６３】
図９は燃料噴射期間初期にニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行し、残りの燃料噴射期間中にニードル弁を全開位置に配置して燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。図９に示すように、燃料噴射期間初期に燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）を実行するためにニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させることが要求されると（時間Ｔ１）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が開始され、圧力制御弁リフト量がゼロから増加せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ４よりも大きくなると）、ニードル弁２は開弁側に移動し始める。
【００６４】
その場合、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動する前に圧力制御弁リフト量が最大値Ｌｍａｘ（＝Ｌ３）まで増加してしまわないように圧力制御弁リフト量の増加速度は比較的低速に設定されている（時間Ｔ１〜時間Ｔ４）。つまり、ピエゾ式アクチュエータ１４に対する印加電圧の増加速度が比較的低速に設定されている。詳細には、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になった時（時間Ｔ４）にニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に到達するように、圧力制御弁リフト量の増加速度は設定されている。次いで、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止せしめられ、燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）が実行される。また、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が停止される。
【００６５】
次いで、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）を実行するためにニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させることが要求されると（時間Ｔ６）、ピエゾ式アクチュエータ１４に対する印加電圧の減少が開始され、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）から減少せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ３よりも（＝Ｌｍａｘ）小さくなると）（時間Ｔ６以降）、ニードル弁２は開弁側に再び移動し始める。
【００６６】
その場合、ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動する前に圧力制御弁リフト量がゼロまで減少してしまわないように圧力制御弁リフト量の減少速度は比較的低速に設定されている（時間Ｔ６〜時間Ｔ９）。つまり、ピエゾ式アクチュエータ１４に対する印加電圧の減少速度が比較的低速に設定されている。ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に突き当たると、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）が実行されることになる。次いで、圧力制御弁リフト量がゼロまで減少すると（時間Ｔ９）、ニードル弁２が全閉位置に向かって移動し始める。ニードル弁２が全閉位置に向かって移動し始めるべき時（時間Ｔ９）に圧力制御弁リフト量がゼロになるように、圧力制御弁リフト量の減少速度は設定されている。
【００６７】
燃料噴射期間初期から燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）を実行するための本実施形態の圧力制御弁制御方法は図７に示した第一の実施形態の圧力制御弁制御方法を同様である。
【００６８】
上述したように、圧力制御弁リフト量を増加させている期間中（図８、図９の時間Ｔ１〜時間Ｔ４）、及び圧力制御弁リフト量を減少させている期間中（図９の時間Ｔ６〜時間Ｔ９）、圧力制御室４から圧力制御弁室７への燃料の流れが許容され、かつ、圧力制御弁室７から低圧燃料リーク通路１３への燃料の流れが許容されることにより、圧力制御室４内の燃料が第二通路１１及び圧力制御弁室７を介して低圧燃料リーク通路１３内に排出されて圧力制御室４内の圧力が低下せしめられる。そのため、ニードル弁２を閉弁側（図１及び図２の下側）に付勢する圧力制御室４内の油圧（燃料圧）とスプリング８のばね圧との和が、ニードル弁２を開弁側（図１及び図２の上側）に付勢する燃料だまり室３内の油圧よりも小さくなり、その結果、ニードル弁２が開弁側に移動せしめられる。
【００６９】
一方で、高圧燃料供給通路８内の圧力が低い場合には、第一通路９を介して圧力制御弁室７内に流入する燃料量が減少するのに伴って圧力制御弁室７内の圧力の減少が早まり、その結果、圧力制御室４内の圧力の減少が早まり、ニードル弁２のリフト速度が増加する。また、燃料温度が低い場合には、燃料の粘性が高くなるのに伴って第一通路９を介して圧力制御弁室７内に流入する燃料量が減少し、圧力制御弁室７内の圧力の減少が早まり、その結果、圧力制御室４内の圧力の減少が早まり、ニードル弁２のリフト速度が増加する。本実施形態ではこれらの事項に鑑み、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が設定される。詳細には、高圧燃料供給通路８内の圧力が低い場合、ニードル弁２のリフト速度が増加することを考慮し、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が比較的高速に設定される。また、燃料温度が低い場合、ニードル弁２のリフト速度が増加することを考慮し、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が比較的高速に設定される。
【００７０】
更に、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも強い場合には、第一通路９を介して圧力制御弁室７内に流入する燃料量が減少するのに伴って圧力制御弁室７内の圧力の減少が早まり、その結果、圧力制御室４内の圧力の減少が早まり、ニードル弁２のリフト速度が増加する。一方、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも弱い場合には、第一通路９を介して圧力制御弁室７内に流入する燃料量が増加するのに伴って圧力制御弁室７内の圧力の低下が遅れ、その結果、圧力制御室４内の圧力の低下が遅れ、ニードル弁２のリフト速度が減少する。本実施形態ではこれらの事項に鑑み、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が、燃料噴射装置の評価段階で補正される。詳細には、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも強い場合、ニードル弁２のリフト速度が増加することを考慮し、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が高速側に補正される。一方、第一通路９の絞り部１０の絞り度合いが設計上の絞り度合いよりも弱い場合、ニードル弁２のリフト速度が減少することを考慮し、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が低速側に補正される。
【００７１】
本実施形態では、第一の実施形態と同様に、ニードル弁リフト量を検出するためのリフト量センサ（図示せず）が設けられている。そのリフト量センサにより、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝Ｌ２）まで移動せしめられ、そこにほぼ停止せしめられた時（図８の時間Ｔ４〜時間Ｔ５、図９の時間Ｔ４〜時間Ｔ６）の実際のニードル弁リフト量が検出され、その値とその時の要求ニードル弁リフト量（＝ＮＬｌｏｗ）との差分に基づいて圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）がフィードバック補正される。詳細には、検出された実際のニードル弁リフト量が要求ニードル弁リフト量（＝ＮＬｌｏｗ）よりも小さい場合には、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が低速側に補正される。一方、検出された実際のニードル弁リフト量が要求ニードル弁リフト量（＝ＮＬｌｏｗ）よりも大きい場合には、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）及び圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が高速側に補正される。このフィードバック補正は、ニードル弁２を中間リフト位置まで移動せしめる毎に実行してもよく、あるいは、所定の時間間隔をおいて定期的に実行してもよい。
【００７２】
本実施形態によれば、ニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させるとき、ニードル弁２がその所定の中間リフト位置まで移動する前に圧力制御弁リフト量が最大値Ｌｍａｘ（＝Ｌ３）まで増加してしまわないように圧力制御弁リフト量の増加速度が比較的低速に設定される（図８、図９の時間Ｔ１〜時間Ｔ４）。そのため、ニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させている途中（図８、図９の時間Ｔ１〜時間Ｔ４）に、圧力制御弁リフト量が最大値Ｌｍａｘ（＝Ｌ３）まで増加してしまうのに伴って第二モード（図３（Ｂ））から第三モード（図４（Ａ））に切り換わってニードル弁２が停止せしめられてしまい、その結果、ニードル弁２がその所定の中間リフト位置までリフトできなくなってしまうのを回避することができる。
【００７３】
更に本実施形態によれば、ニードル弁２を中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させるとき、ニードル弁２が全開位置まで移動する前に圧力制御弁リフト量がゼロまで減少してしまわないように圧力制御弁リフト量の減少速度が比較的低速に設定される（図９の時間Ｔ６〜時間Ｔ９）。そのため、ニードル弁２を中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させている途中（図９の時間Ｔ６〜時間Ｔ９）に、圧力制御弁リフト量がゼロまで減少してしまうのに伴って第二モード（図３（Ｂ））から第一モード（図３（Ａ））に切り換わってニードル弁２が全閉位置に向かって移動し始めてしまい、その結果、ニードル弁２が全開位置までリフトできなくなってしまうのを回避することができる。
【００７４】
また本実施形態によれば、圧力制御弁リフト量に応じて変化する圧力制御室４内の圧力が、更に高圧燃料供給通路８内の圧力及び燃料温度にも応じて変化してしまうことに鑑み、圧力制御室４内の圧力を要求通りに制御するために、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）又は圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が高圧燃料供給通路８内の圧力と燃料温度とに基づいて制御される。そのため、圧力制御室４内の圧力を要求通りに制御することができる。
【００７５】
更に本実施形態によれば、圧力制御弁リフト量に応じて変化する圧力制御室４内の圧力が、更に第一通路９を通過する燃料流量にも応じて変化してしまうことに鑑み、圧力制御室４内の圧力を要求通りに制御するために、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）又は圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）が第一通路９を通過する燃料流量に基づいて補正される。そのため、補正を行わない場合よりも正確に、圧力制御室４内の圧力を要求通りに制御することができる。
【００７６】
更に本実施形態によれば、ニードル弁２が所定の中間リフト位置まで移動せしめられた時（図８の時間Ｔ４〜時間Ｔ５、図９の時間Ｔ４〜時間Ｔ６）の実際のニードル弁リフト量とその時の要求ニードル弁リフト量ＮＬｌｏｗとの差分に基づいて、圧力制御弁リフト量の増加速度（図８、図９の時間Ｔ１〜時間Ｔ４）又は圧力制御弁リフト量の減少速度（図９の時間Ｔ６〜時間Ｔ９）がフィードバック補正される。そのため、フィードバック補正が行われない場合よりも正確に、ニードル弁リフト量を要求通りに制御することができる。
【００７７】
以下、本発明の燃料噴射装置の第三の実施形態について説明する。本実施形態の構成は、後述する点を除いて上述した第一及び第二の実施形態の構成と同様である。従って、後述する点を除いて第一及び第二の実施形態と同様の効果を奏することができる。本実施形態においても、ニードル弁リフト量を検出するためのリフト量センサ（図示せず）が設けられている。
【００７８】
図１０は燃料噴射期間初期にニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行し、残りの燃料噴射期間中にニードル弁を全開位置に配置して燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。図１０に示すように、燃料噴射期間初期に燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）を実行するためにニードル弁２を全閉位置から所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）まで移動させることが要求されると（時間Ｔ１）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が開始され、圧力制御弁リフト量がゼロから増加せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ４よりも大きくなると）（時間Ｔ２）、ニードル弁２は開弁側に移動し始める。
【００７９】
次いで、ニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に向かって移動させ続けるために、圧力制御弁リフト量がＬ２のまま固定される（時間Ｔ２〜時間Ｔ３）。次いでニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止させるために圧力制御弁リフト量を再び増加させることが必要になった時（時間Ｔ３）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が再び開始され、圧力制御弁リフト量が再び増加せしめられる。圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になった時（時間Ｔ４）にニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）に到達するように、時間Ｔ３は設定されている。次いで、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ニードル弁２が所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）にほぼ停止せしめられ、燃料噴射率を低く抑えた燃料噴射（燃料噴射率＝ＩＲｌｏｗ）が実行される。また、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）になると（時間Ｔ４）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が停止される。
【００８０】
次いで、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）を実行するためにニードル弁２を所定の中間リフト位置（ニードル弁リフト量＝ＮＬｌｏｗ）から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させることが要求されると（時間Ｔ６）、ピエゾ式アクチュエータ１４に対する印加電圧の減少が開始され、圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）から減少せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ３（＝Ｌｍａｘ）よりも小さくなると）（時間Ｔ６以降）、ニードル弁２は開弁側に再び移動し始める。
【００８１】
次いで、ニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に向かって移動させ続けるために、圧力制御弁リフト量がＬ２のまま固定される（時間Ｔ７〜時間Ｔ８’）。ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に突き当たると、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）が実行されることになる。ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に突き当たったことがリフト量センサによって検出されると（時間Ｔ８’）、圧力制御弁リフト量がＬ４まで減少せしめられ、圧力制御弁６が第四の位置（図４（Ｂ））に配置される。次いで、燃料噴射を終了するためにニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）から全閉位置まで移動させることが要求されると、ピエゾ式アクチュエータ１４に対する印加電圧の減少が再び開始され、圧力制御弁リフト量がゼロまで減少せしめられる。次いで、圧力制御弁リフト量がゼロまで減少すると（時間Ｔ９）、ニードル弁２が全閉位置に向かって移動し始める。ニードル弁２が全閉位置に向かって移動し始めるべき時（時間Ｔ９）に圧力制御弁リフト量がゼロになるように、ピエゾ式アクチュエータ１４に対する印加電圧の減少を再び開始するタイミングは設定されている。
【００８２】
図１１は燃料噴射期間初期から燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。図１１に示すように、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）を実行するためにニードル弁２を全閉位置から全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動させることが要求されると（時間Ｔ１）、ピエゾ式アクチュエータ１４に対する印加電圧の増加が開始され、圧力制御弁リフト量がゼロから増加せしめられる。圧力制御弁リフト量がＬ２になると（詳細には圧力制御弁リフト量がＬ４よりも大きくなると）（時間Ｔ２）、ニードル弁２は開弁側に移動し始める。
【００８３】
次いで、ニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に向かって移動させ続けるために、圧力制御弁リフト量がＬ２のまま固定される（時間Ｔ２〜時間Ｔ８”）。ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に突き当たると、燃料噴射率を高くした燃料噴射（燃料噴射率＝ＩＲｈｉｇｈ）が実行されることになる。ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に突き当たったことがリフト量センサによって検出されると（時間Ｔ８”）、圧力制御弁リフト量がＬ４まで減少せしめられ、圧力制御弁６が第四の位置（図４（Ｂ））に配置される。次いで、燃料噴射を終了するためにニードル弁２を全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）から全閉位置まで移動させることが要求されると、ピエゾ式アクチュエータ１４に対する印加電圧の減少が再び開始され、圧力制御弁リフト量がゼロまで減少せしめられる。次いで、圧力制御弁リフト量がゼロまで減少すると（時間Ｔ９）、ニードル弁２が全閉位置に向かって移動し始める。ニードル弁２が全閉位置に向かって移動し始めるべき時（時間Ｔ９）に圧力制御弁リフト量がゼロになるように、ピエゾ式アクチュエータ１４に対する印加電圧の減少を再び開始するタイミングは設定されている。
【００８４】
本実施形態によれば、ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）に位置している時（図１０の時間Ｔ８’〜時間Ｔ９、図１１の時間Ｔ８”〜時間Ｔ９）に、圧力制御弁リフト量が第二モード時（図３（Ｂ））及び第三モード時（図４（Ａ））の圧力制御弁リフト量よりも小さくなっている第四の位置（図４（Ｂ））に圧力制御弁６が配置される。そのため、ニードル弁２が全開位置に位置している時に圧力制御弁が第二の位置に配置される場合や第三の位置に配置される場合に比べ、低圧燃料リーク通路１３内に排出される燃料量を低減することができる。それゆえ、高圧燃料が低圧燃料リーク通路１３内に排出されるのに伴って燃料温度が上昇してしまうのを抑制することができる。
【００８５】
更に本実施形態によれば、ニードル弁２が全開位置（ニードル弁リフト量＝ＮＬｈｉｇｈ）まで移動したら即座に圧力制御弁６が第二の位置（図３（Ｂ））から第四の位置（図４（Ｂ））まで移動せしめられる（図１０の時間Ｔ８’、図１１の時間Ｔ８”）。そのため、低圧燃料リーク通路１３内に排出される燃料量を最小にすることができる。
【００８６】
【発明の効果】
請求項１に記載の発明によれば、圧力制御弁を第一の位置又は第二の位置に配置し、圧力制御室内の圧力を増減させることにより、噴孔開閉弁を閉弁側に付勢する力を増減させることができる。それゆえ、高圧燃料供給通路内の圧力を増加させなくても、圧力制御弁を第二の位置に配置し、圧力制御室内の圧力を減少させて噴孔開閉弁を閉弁側に付勢する力を減少させることにより、噴孔開閉弁を全閉位置から中間リフト位置まで移動させることができる。更に密閉された圧力制御室によって噴孔開閉弁をホールドすることができる。それゆえ、高圧燃料供給通路内の圧力を微調節しなくても、噴孔開閉弁を全開位置と全閉位置との間の任意の所望のリフト位置にほぼ停止させることができる。つまり、噴孔開閉弁を所望の中間リフト位置まで移動させ、そこにほぼ停止させることにより、燃料噴射率を所望の燃料噴射率に切り換えることができる。
【００８８】
請求項１に記載の発明によれば、噴孔開閉弁を全閉位置から所定の中間リフト位置まで移動させている途中に、圧力制御弁リフト量が最大値まで増加してしまうのに伴って第二モードから第三モードに切り換わって噴孔開閉弁が停止せしめられてしまい、その結果、噴孔開閉弁がその所定の中間リフト位置までリフトできなくなってしまうのを回避することができる。
【００９０】
請求項２に記載の発明によれば、噴孔開閉弁を中間リフト位置から全開位置まで移動させている途中に、圧力制御弁リフト量がゼロまで減少してしまうのに伴って第二モードから第一モードに切り換わって噴孔開閉弁が全閉位置に向かって移動し始めてしまい、その結果、噴孔開閉弁が全開位置までリフトできなくなってしまうのを回避することができる。
【００９３】
請求項３に記載の発明によれば、圧力制御室内の圧力を要求通りに制御することができる。
【００９４】
請求項４に記載の発明によれば、より正確に、圧力制御室内の圧力を要求通りに制御することができる。
【００９５】
請求項５に記載の発明によれば、フィードバック補正が行われない場合よりも正確に、噴孔開閉弁リフト量を要求通りに制御することができる。
【００９６】
請求項６に記載の発明によれば、噴孔開閉弁が全開位置に位置している時に圧力制御弁が第二の位置に配置される場合や第三の位置に配置される場合に比べ、低圧燃料リーク通路内に排出される燃料量を低減することができる。それゆえ、高圧燃料が低圧燃料リーク通路内に排出されるのに伴って燃料温度が上昇してしまうのを抑制することができる。
【００９７】
請求項７に記載の発明によれば、低圧燃料リーク通路内に排出される燃料量を最小にすることができる。
【図面の簡単な説明】
【図１】本発明の燃料噴射装置の第一の実施形態の概略断面図である。
【図２】図１の一部を拡大した拡大図である。
【図３】圧力制御弁の第一モード及び第二モードを示した図である。
【図４】圧力制御弁の第三モード及び第四モードを示した図である。
【図５】第一の実施形態におけるニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行するための圧力制御弁制御方法を示した図である。
【図６】第一の実施形態における燃料噴射期間初期にニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行し、残りの燃料噴射期間中にニードル弁を全開位置に配置して燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。
【図７】第一の実施形態における燃料噴射期間初期から燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。
【図８】第二の実施形態におけるニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行するための圧力制御弁制御方法を示した図である。
【図９】第二の実施形態における燃料噴射期間初期にニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行し、残りの燃料噴射期間中にニードル弁を全開位置に配置して燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。
【図１０】第三の実施形態における燃料噴射期間初期にニードル弁を全開位置と全閉位置との間の中間リフト位置に維持して燃料噴射率を低く抑えた燃料噴射を実行し、残りの燃料噴射期間中にニードル弁を全開位置に配置して燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。
【図１１】第三の実施形態における燃料噴射期間初期から燃料噴射率を高くした燃料噴射を実行するための圧力制御弁制御方法を示した図である。
【符号の説明】
１…燃料噴射用噴孔
２…ニードル弁
３…燃料だまり室
４…圧力制御室
５…スプリング
６…圧力制御弁
７…圧力制御弁室
８…高圧燃料供給通路
９…第一通路
１０，１２…絞り部
１１…第二通路
１３…低圧燃料リーク通路
１４…ピエゾ式アクチュエータ
１５…作動油
１６…スプリング[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device.
[0002]
[Prior art]
Conventionally, a nozzle opening / closing valve that opens and closes a fuel injection nozzle hole, a valve opening side biasing means that biases the nozzle hole opening / closing valve toward the valve opening side, and a valve closing that biases the nozzle hole opening / closing valve toward the valve closing side. There is known a fuel injection device including a side urging unit. An example of this type of fuel injection device is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-334072. In the fuel injection device described in JP-A-3-334072, the valve-opening side urging means is formed by a fuel reservoir chamber in the nozzle body, and the valve-closing side urging means is constituted by a spring.
[0003]
[Problems to be solved by the invention]
However, in the fuel injection device described in JP-A-8-334072, the valve closing side biasing means is constituted by a spring, so that the injection hole opening / closing valve is moved from the fully closed position to the fully open position and the fully closed position. In order to move to the intermediate lift position, the pressure in the fuel sump chamber is increased, that is, the fuel supply pressure is increased, and the force that biases the nozzle hole opening / closing valve to the valve opening side closes the nozzle hole opening / closing valve. It must be greater than the force that urges the valve. In addition, in order to substantially stop the nozzle hole opening / closing valve at the intermediate lift position, the pressure in the fuel sump chamber is adjusted, the force for biasing the nozzle hole opening / closing valve to the valve opening side, and the nozzle hole opening / closing valve to the valve closing side. You have to balance the force to be energized. In addition, in order to substantially stop the nozzle hole opening / closing valve at the desired intermediate lift position, the force for urging the nozzle hole opening / closing valve to the valve opening side at the desired intermediate lift position and the nozzle hole opening / closing valve to the valve closing side. The pressure in the fuel sump chamber must be fine-tuned to balance the force energizing the fuel.
[0004]
In view of the above problems, the present invention can move the nozzle hole opening / closing valve from the fully closed position to the intermediate lift position without the need to increase the fuel supply pressure, and can open and close the nozzle hole without the need for fine adjustment of the fuel supply pressure. It is an object of the present invention to provide a fuel injection device capable of substantially stopping the valve at a desired intermediate lift position, that is, a fuel injection device capable of switching a fuel injection rate waveform to a desired fuel injection rate waveform.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, the nozzle hole opening / closing valve for opening / closing the fuel injection nozzle hole, the valve opening side biasing means for biasing the nozzle hole opening / closing valve to the valve opening side, and the nozzle hole opening / closing And a valve closing side biasing means for biasing the valve toward the valve closing side, wherein the valve closing side biasing means has a pressure control chamber, and controls the pressure in the pressure control chamber. A pressure control valve is disposed in the pressure control valve chamber, the high pressure fuel supply passage and the pressure control valve chamber are communicated by a first passage, the pressure control valve chamber and the pressure control chamber are communicated by a second passage, During the first mode in which the pressure control valve is disposed at the first position, the flow of fuel from the pressure control valve chamber to the low pressure fuel leak passage is blocked, so that the fuel in the high pressure fuel supply passage is in the first mode. The pressure control is supplied to the pressure control chamber through the one passage and the second passage. As a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is larger than the force for urging the nozzle hole opening / closing valve toward the valve opening side, so that the nozzle hole opening / closing valve is increased. Is moved toward the fully closed position, and in the second mode in which the pressure control valve is disposed at the second position, the flow of fuel from the pressure control chamber to the pressure control valve chamber is allowed, and By allowing the fuel flow from the pressure control valve chamber to the low pressure fuel leak passage, the fuel in the pressure control chamber is discharged into the low pressure fuel leak passage through the second passage and the pressure control valve chamber. As a result, the pressure in the pressure control chamber is reduced, and as a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is smaller than the force for urging the nozzle hole opening / closing valve toward the valve opening side. The nozzle hole opening / closing valve is moved toward the fully open position; During the third mode in which the force control valve is arranged at the third position, the flow of fuel between the pressure control chamber and the pressure control valve chamber is shut off, the pressure control chamber is sealed, and the sealed pressure The injection hole opening / closing valve is held by the control chamber, so that the injection hole opening / closing valve is substantially stopped at an arbitrary lift position between the fully open position and the fully closed position, The pressure control valve lift amount is zero in the first mode, the pressure control valve lift amount is the maximum value in the third mode, and the pressure control valve lift amount is between them in the second mode. When the nozzle hole opening / closing valve is required to move from the fully closed position to a predetermined intermediate lift position, the pressure control valve lift amount is increased from zero to move the nozzle hole opening / closing valve. And increasing the pressure control valve lift amount so that the pressure control valve lift amount does not increase to the maximum value before the nozzle hole opening / closing valve moves to the predetermined intermediate lift position, When the nozzle hole opening / closing valve moves to the predetermined intermediate lift position, the pressure control valve lift amount is fixed to the maximum value so that the nozzle hole opening / closing valve substantially stops at the predetermined intermediate lift position. The A fuel injection device is provided.
[0006]
In the fuel injection device according to the first aspect, the valve closing side urging means has a pressure control chamber, and the pressure in the pressure control chamber is controlled by the pressure control valve. Therefore, by arranging the pressure control valve at the first position or the second position and increasing or decreasing the pressure in the pressure control chamber, it is possible to increase or decrease the force that biases the nozzle hole opening / closing valve toward the valve closing side. Therefore, even if the pressure in the high pressure fuel supply passage is not increased, the pressure control valve is disposed at the second position, the pressure in the pressure control chamber is decreased, and the nozzle hole opening / closing valve is biased toward the valve closing side. By reducing the force, the nozzle hole opening / closing valve can be moved from the fully closed position to the intermediate lift position. Furthermore, in the fuel injection device according to the first aspect, the pressure control chamber can be sealed by the pressure control valve when the pressure control valve is disposed at the third position. Therefore, the nozzle hole opening / closing valve can be held by the sealed pressure control chamber. Therefore, the injection hole on-off valve can be substantially stopped at any desired lift position between the fully open position and the fully closed position without finely adjusting the pressure in the high pressure fuel supply passage. That is, the fuel injection rate waveform can be switched to the desired fuel injection rate waveform by moving the nozzle hole opening / closing valve to the desired intermediate lift position and substantially stopping there.
[0010]
Claim 1 In the fuel injection device described in 1), when the nozzle hole opening / closing valve is moved from the fully closed position to the predetermined intermediate lift position, the pressure control valve lift amount is maximized before the nozzle hole opening / closing valve moves to the predetermined intermediate lift position. Increase rate of pressure control valve lift so as not to increase to the value Set up Determined. Therefore, while the nozzle hole opening / closing valve is being moved from the fully closed position to the predetermined intermediate lift position, the pressure control valve lift amount is switched from the second mode to the third mode as the lift amount increases to the maximum value. In other words, it is possible to prevent the nozzle hole opening / closing valve from being stopped and, as a result, the nozzle hole opening / closing valve from being lifted to its predetermined intermediate lift position.
[0013]
Claim 2 According to the invention described in (4), when it is required to move the nozzle hole opening / closing valve from the fully closed position to a predetermined intermediate lift position and then to the fully open position, the pressure control valve lift amount is increased from zero. The pressure control valve lift so that the pressure control valve lift amount does not increase to the maximum value before the nozzle hole open / close valve moves to the predetermined intermediate lift position. Volume increase rate Set up Then, when the nozzle hole opening / closing valve moves to the predetermined intermediate lift position, the pressure control valve lift amount is fixed to the maximum value, so that the nozzle hole opening / closing valve is substantially stopped at the predetermined intermediate lift position. Then, the lift amount of the pressure control valve is decreased from the maximum value, the nozzle hole opening / closing valve is moved again toward the fully open position, and the pressure control valve lift amount is zero before the nozzle hole opening / closing valve moves to the fully open position. Decrease speed of pressure control valve lift amount so as not to decrease until Set up The nozzle hole opening / closing valve is moved to a fully open position. 1 Is provided.
[0014]
Claim 2 In the fuel injection device described in 1), when the nozzle hole opening / closing valve is moved from the intermediate lift position to the fully open position, the pressure control valve lift amount does not decrease to zero before the nozzle hole opening / closing valve moves to the fully open position. Pressure control valve lift amount decreasing speed Set up Determined. Therefore, while the nozzle hole opening / closing valve is being moved from the intermediate lift position to the fully open position, the pressure control valve lift amount is reduced to zero and the second mode is switched to the first mode. It can be avoided that the on-off valve starts to move toward the fully closed position, and as a result, the injection hole on-off valve cannot be lifted to the fully open position.
[0019]
Claim 3 The pressure control valve lift amount increasing speed or the pressure control valve lift amount decreasing speed is calculated based on the pressure in the high-pressure fuel supply passage and the fuel temperature. 1 or 2 Is provided.
[0020]
Claim 3 In view of the fact that the pressure in the pressure control chamber that changes in accordance with the pressure control valve lift amount also changes in accordance with the pressure in the high-pressure fuel supply passage and the fuel temperature, In order to control the indoor pressure as required, the increasing speed of the pressure control valve lift amount or the decreasing speed of the pressure control valve lift amount is controlled based on the pressure in the high pressure fuel supply passage and the fuel temperature. Therefore, the pressure in the pressure control chamber can be controlled as required.
[0021]
Claim 4 According to the invention described in the first passage Aperture level of the aperture On the basis of the pressure control valve lift rate increase rate or pressure control valve lift rate decrease rate Setting Claims to be made 3 Is provided.
[0022]
Claim 4 In view of the fact that the pressure in the pressure control chamber that changes in accordance with the pressure control valve lift amount also changes in accordance with the fuel flow rate that passes through the first passage, In order to control the pressure as required, the rate of increase of the pressure control valve lift amount or the rate of decrease of the pressure control valve lift amount is the first passage. Aperture level of the aperture On the basis of the Setting Is done. for that reason, Such a setting The pressure in the pressure control chamber can be controlled as required more accurately than in the case of not performing the above.
[0023]
Claim 5 According to the invention, the lift amount detecting means for detecting the lift amount of the nozzle hole opening / closing valve is provided, and the actual nozzle hole opening / closing when the nozzle hole opening / closing valve is moved to the predetermined intermediate lift position is provided. Based on the difference between the valve lift amount and the required orifice opening / closing valve lift amount at that time, the period during which the pressure control valve lift amount is fixed, the increasing speed of the pressure control valve lift amount, or the decreasing speed of the pressure control valve lift amount is fed back Claims amended 3 or 4 Is provided.
[0024]
Claim 5 In the fuel injection device described in the above, based on the difference between the actual nozzle hole opening / closing valve lift amount when the nozzle hole opening / closing valve is moved to the predetermined intermediate lift position and the required nozzle hole opening / closing valve lift amount at that time, The period during which the pressure control valve lift amount is fixed, the increasing speed of the pressure control valve lift amount, or the decreasing speed of the pressure control valve lift amount is feedback corrected. Therefore, the injection hole opening / closing valve lift amount can be controlled as required more accurately than when feedback correction is not performed.
[0025]
Claim 6 According to the invention described in A nozzle opening / closing valve that opens and closes the fuel injection nozzle hole, a valve opening side biasing means that biases the nozzle hole opening / closing valve toward the valve opening side, and a valve closing valve that biases the nozzle hole opening / closing valve toward the valve closing side. In the fuel injection device comprising the side biasing means, the valve closing side biasing means has a pressure control chamber, and a pressure control valve for controlling the pressure in the pressure control chamber is disposed in the pressure control valve chamber. The high pressure fuel supply passage and the pressure control valve chamber communicate with each other through a first passage, the pressure control valve chamber and the pressure control chamber communicate with each other through a second passage, and the pressure control valve is disposed at a first position. In the first mode, the flow of fuel from the pressure control valve chamber to the low pressure fuel leak passage is blocked, so that the fuel in the high pressure fuel supply passage passes through the first passage and the second passage. The pressure is supplied to the pressure control chamber and the pressure in the pressure control chamber is increased. As a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is greater than the force for urging the nozzle hole opening / closing valve toward the valve opening side, causing the nozzle hole opening / closing valve to move toward the fully closed position. In the second mode in which the pressure control valve is disposed at the second position, the flow of fuel from the pressure control chamber to the pressure control valve chamber is allowed, and the low pressure fuel leak from the pressure control valve chamber By allowing the fuel flow to the passage, the fuel in the pressure control chamber is discharged into the low-pressure fuel leak passage through the second passage and the pressure control valve chamber, and the pressure in the pressure control chamber is reduced. As a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is smaller than the force for urging the nozzle hole opening / closing valve toward the valve opening side, so that the nozzle hole opening / closing valve is in the fully opened position. And the pressure control valve is placed in the third position. In the third mode, the flow of fuel between the pressure control chamber and the pressure control valve chamber is shut off, the pressure control chamber is sealed, and the nozzle hole opening / closing valve is held by the sealed pressure control chamber. By so doing, the nozzle hole on-off valve can be stopped almost at an arbitrary lift position between the fully open position and the fully closed position, In the fourth mode, in which the pressure control valve lift amount is smaller than the pressure control valve lift amount in the second mode and the third mode, the pressure control valve lift amount is set in the fourth mode. The force for energizing the valve closing side is equal to the force for energizing the nozzle hole opening / closing valve to the valve opening side, and the pressure control valve is operated when the nozzle hole opening / closing valve is located at the fully open position. And place it in the fourth position Burning A fuel injection device is provided.
[0026]
Claim 6 In the fuel injection device described in 1), when the nozzle hole opening / closing valve is located at the fully open position, the pressure control valve lift amount is smaller than the pressure control valve lift amount in the second mode and the third mode. Pressure control valves are arranged at the four positions. Therefore, the pressure control valve is discharged into the low pressure fuel leak passage as compared with the case where the pressure control valve is arranged at the second position or the third position when the nozzle hole on-off valve is located at the fully open position. The amount of fuel can be reduced. Therefore, it is possible to suppress the fuel temperature from rising as the high pressure fuel is discharged into the low pressure fuel leak passage.
[0027]
Claim 7 According to the invention, the lift amount detecting means for detecting the lift amount of the nozzle hole opening / closing valve is provided, and the pressure control valve is immediately moved from the second position to the second position when the nozzle hole opening / closing valve moves to the fully open position. Claims moved to the fourth position 6 Is provided.
[0028]
Claim 7 In the fuel injection device described in 1), the pressure control valve is moved from the second position to the fourth position as soon as the nozzle hole opening / closing valve moves to the fully open position. Therefore, the amount of fuel discharged into the low pressure fuel leak passage can be minimized.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0034]
FIG. 1 is a schematic sectional view of a first embodiment of the fuel injection device of the present invention, and FIG. 2 is an enlarged view of a part of FIG. 1 and 2, 1 is a fuel injection nozzle hole, 2 is a needle valve that opens and closes the fuel injection nozzle hole 1, and 3 is a needle valve 2 that urges the valve opening side (upper side in FIGS. 1 and 2). The fuel reservoir chamber 4 is a pressure control chamber for biasing the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2). 5 is a spring for biasing the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2), 6 is a pressure control valve for controlling the pressure in the pressure control chamber 4, and 7 is a pressure control valve. Reference numeral 6 denotes a pressure control valve chamber disposed inside. Reference numeral 8 denotes a high pressure fuel supply passage, 9 denotes a first passage communicating the high pressure fuel supply passage 8 and the pressure control valve chamber 7, and 10 denotes a throttle portion formed in the first passage 9. Reference numeral 11 denotes a second passage that communicates the pressure control valve chamber 7 and the pressure control chamber 4, reference numeral 12 denotes a throttle formed in the second passage 11, and reference numeral 13 denotes a low-pressure fuel leak passage. Reference numeral 14 denotes a piezo actuator for driving the pressure control valve 6, and 15 denotes hydraulic oil disposed between the pressure control valve 6 and the piezo actuator 14. Specifically, the fuel that has not been injected from the fuel injection nozzle 1 is used as the hydraulic oil 15. 15 is a seat portion on which the pressure control valve 6 is seated when fully closed, and 16 is a spring for biasing the pressure control valve 6 toward the valve closing side (the upper side in FIGS. 1 and 2).
[0035]
FIG. 3 is a diagram showing a first mode and a second mode of the pressure control valve. Specifically, FIG. 3A shows a first mode in which the pressure control valve 6 is disposed at the fully closed position (first position), and FIG. 3B shows that the pressure control valve 6 is in the intermediate lift position. The second mode arranged at (second position) is shown. As shown in FIG. 3A, when the pressure control valve 6 is fully closed (pressure control valve lift amount = zero), the flow of fuel from the pressure control valve chamber 7 to the low pressure fuel leak passage 13 is interrupted. As a result, the fuel in the high-pressure fuel supply passage 8 is supplied into the pressure control chamber 4 via the first passage 9 and the second passage 11, and the pressure in the pressure control chamber 4 is increased. Therefore, the sum of the hydraulic pressure (fuel pressure) in the pressure control chamber 4 that biases the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2) and the spring pressure of the spring 5 opens the needle valve 2. The hydraulic pressure in the fuel sump chamber 3 urged toward the valve side (the upper side in FIGS. 1 and 2) becomes larger, and as a result, the needle valve 2 is moved to the valve closing side or is maintained in the fully closed position. . That is, if the pressure control valve 6 continues to be fully closed, the needle valve 2 is fully closed.
[0036]
On the other hand, as shown in FIG. 3 (B), when the pressure control valve 6 is disposed at the intermediate lift position (second position) (pressure control valve lift amount = L2), the pressure control chamber 4 is changed to the pressure control valve chamber. 7 is allowed to flow, and the fuel flow from the pressure control valve chamber 7 to the low pressure fuel leak passage 13 is allowed, so that the fuel in the pressure control chamber 4 flows into the second passage 11 and the pressure control. The pressure in the pressure control chamber 4 is lowered by being discharged into the low-pressure fuel leak passage 13 through the valve chamber 7. Therefore, the sum of the hydraulic pressure (fuel pressure) in the pressure control chamber 4 that biases the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2) and the spring pressure of the spring 8 opens the needle valve 2. The hydraulic pressure in the fuel sump chamber 3 urged toward the valve side (the upper side in FIGS. 1 and 2) becomes smaller, and as a result, the needle valve 2 is moved to the valve opening side or is maintained at the fully opened position. That is, when the pressure control valve 6 is maintained at the intermediate lift position, the needle valve 2 is fully opened.
[0037]
FIG. 4 is a diagram showing a third mode and a fourth mode of the pressure control valve. Specifically, FIG. 4A shows a third mode in which the pressure control valve 6 is arranged at the fully open position (third position), and FIG. 4B shows the second mode (FIG. 3B). ) Shows a fourth mode in which the pressure control valve 6 is arranged at a fourth position where the pressure control valve lift amount is smaller than the pressure control valve lift amount L2. As shown in FIG. 4A, when the pressure control valve 6 is fully opened (pressure control valve lift amount = L3 = Lmax), the flow of fuel between the pressure control chamber 4 and the pressure control valve chamber 7 is interrupted. Thus, the pressure control chamber 4 is sealed, and the needle valve 2 is held by the sealed pressure control chamber 4, so that the needle valve 2 almost stops at any lift position between the fully open position and the fully closed position. I'm damned.
[0038]
As shown in FIG. 4B, when the pressure control valve 6 is arranged at the fourth position (pressure control valve lift amount = L4), the fuel in the high-pressure fuel supply passage 8 flows into the first passage 9 and the second passage. While being supplied into the pressure control chamber 4 through the passage 11, the fuel in the pressure control chamber 4 is discharged into the low-pressure fuel leak passage 13 through the second passage 11 and the pressure control valve chamber 7. Therefore, the sum of the hydraulic pressure (fuel pressure) in the pressure control chamber 4 that biases the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2) and the spring pressure of the spring 8 opens the needle valve 2. It becomes equal to the hydraulic pressure in the fuel sump chamber 3 urging to the valve side (upper side in FIGS. 1 and 2), and as a result, the needle valve 2 almost stops at an arbitrary lift position between the fully open position and the fully closed position. I'm damned.
[0039]
FIG. 5 is a view showing a pressure control valve control method for executing fuel injection with a low fuel injection rate by maintaining the needle valve at an intermediate lift position between the fully open position and the fully closed position. As shown in FIG. 5, in order to execute fuel injection with a low fuel injection rate (fuel injection rate = IRlow), the needle valve 2 is moved from the fully closed position to a predetermined intermediate lift position (needle valve lift amount = NLlow). When it is required to move (time T1), an increase in the voltage applied to the piezoelectric actuator 14 is started, and the pressure control valve lift amount is increased from zero. When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes larger than L4) (time T2), the needle valve 2 starts to move toward the valve opening side.
[0040]
Next, in order to continue moving the needle valve 2 toward a predetermined intermediate lift position (needle valve lift amount = NLlow), the pressure control valve lift amount is fixed at L2 (time T2 to time T3). Next, when it is necessary to increase the pressure control valve lift amount again (time T3) in order to substantially stop the needle valve 2 at the predetermined intermediate lift position (needle valve lift amount = NLlow), the piezoelectric actuator 14 is The increase of the applied voltage is started again, and the pressure control valve lift amount is increased again. The time T3 is set so that the needle valve 2 reaches a predetermined intermediate lift position (needle valve lift amount = NLlow) when the pressure control valve lift amount becomes L3 (= Lmax) (time T4). .
[0041]
Next, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the needle valve 2 is almost stopped at a predetermined intermediate lift position (needle valve lift amount = NLlow). Further, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the increase of the applied voltage to the piezo actuator 14 is stopped. Next, when it is required to move the needle valve 2 from the predetermined intermediate lift position (needle valve lift amount = NLlow) to the fully closed position in order to end the fuel injection (time T5), the application to the piezo actuator 14 is performed. The voltage starts to decrease and the pressure control valve lift amount is reduced to zero.
[0042]
FIG. 6 shows that the needle valve is maintained at an intermediate lift position between the fully open position and the fully closed position at the beginning of the fuel injection period to perform fuel injection with a low fuel injection rate, and the needle valve is used during the remaining fuel injection period. It is the figure which showed the pressure control valve control method for performing the fuel injection which has arrange | positioned in the fully open position and made the fuel injection rate high. As shown in FIG. 6, the needle valve 2 is moved from the fully closed position to a predetermined intermediate lift position (needle valve lift) in order to execute fuel injection (fuel injection rate = IRlow) with a low fuel injection rate at the beginning of the fuel injection period. When it is required to move to (amount = NLlow) (time T1), an increase in the applied voltage to the piezo actuator 14 is started, and the pressure control valve lift amount is increased from zero. When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes larger than L4) (time T2), the needle valve 2 starts to move toward the valve opening side.
[0043]
Next, in order to continue moving the needle valve 2 toward a predetermined intermediate lift position (needle valve lift amount = NLlow), the pressure control valve lift amount is fixed at L2 (time T2 to time T3). Next, when it is necessary to increase the pressure control valve lift amount again (time T3) in order to substantially stop the needle valve 2 at the predetermined intermediate lift position (needle valve lift amount = NLlow), the piezoelectric actuator 14 is The increase of the applied voltage is started again, and the pressure control valve lift amount is increased again. The time T3 is set so that the needle valve 2 reaches a predetermined intermediate lift position (needle valve lift amount = NLlow) when the pressure control valve lift amount becomes L3 (= Lmax) (time T4). . Next, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the needle valve 2 is almost stopped at the predetermined intermediate lift position (needle valve lift amount = NLlow), and the fuel injection rate is kept low. Fuel injection (fuel injection rate = IRlow) is executed. Further, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the increase of the applied voltage to the piezo actuator 14 is stopped.
[0044]
Next, the needle valve 2 is moved from the predetermined intermediate lift position (needle valve lift amount = NLlow) to the fully open position (needle valve lift amount = NLhigh) in order to execute fuel injection with increased fuel injection rate (fuel injection rate = IRhigh). Is required (time T6), a decrease in the applied voltage to the piezo actuator 14 is started, and the pressure control valve lift amount is decreased from L3 (= Lmax). When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes smaller than L3 (= Lmax)) (after time T6), the needle valve 2 starts to move again toward the valve opening side.
[0045]
Next, in order to continue to move the needle valve 2 toward the fully opened position (needle valve lift amount = NLhigh), the pressure control valve lift amount is fixed at L2 (time T7 to time T8). When the needle valve 2 hits the fully open position (needle valve lift amount = NLhigh), fuel injection with a higher fuel injection rate (fuel injection rate = IRhigh) is executed. Next, when it is required to move the needle valve 2 from the fully open position (needle valve lift amount = NLhigh) to the fully closed position in order to end the fuel injection (time T8), the voltage applied to the piezo actuator 14 decreases. Is started again and the pressure control valve lift is reduced to zero. Next, when the pressure control valve lift amount decreases to zero (time T9), the needle valve 2 starts to move toward the fully closed position. The time T8 is set so that the pressure control valve lift amount becomes zero when the needle valve 2 should start moving toward the fully closed position (time T9).
[0046]
FIG. 7 is a view showing a pressure control valve control method for executing fuel injection with a high fuel injection rate from the beginning of the fuel injection period. As shown in FIG. 7, the needle valve 2 can be moved from the fully closed position to the fully open position (needle valve lift amount = NLhigh) in order to execute fuel injection with a high fuel injection rate (fuel injection rate = IRhigh). When requested (time T1), an increase in the applied voltage to the piezoelectric actuator 14 is started, and the pressure control valve lift amount is increased from zero. When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes larger than L4) (time T2), the needle valve 2 starts to move toward the valve opening side.
[0047]
Next, in order to continue to move the needle valve 2 toward the fully open position (needle valve lift amount = NLhigh), the pressure control valve lift amount is fixed at L2 (time T2 to time T8). When the needle valve 2 hits the fully open position (needle valve lift amount = NLhigh), fuel injection with a higher fuel injection rate (fuel injection rate = IRhigh) is executed. Next, when it is required to move the needle valve 2 from the fully open position (needle valve lift amount = NLhigh) to the fully closed position in order to end the fuel injection (time T8), the voltage applied to the piezo actuator 14 decreases. Is started again and the pressure control valve lift is reduced to zero. Next, when the pressure control valve lift amount decreases to zero (time T9), the needle valve 2 starts to move toward the fully closed position. The time T8 is set so that the pressure control valve lift amount becomes zero when the needle valve 2 should start moving toward the fully closed position (time T9).
[0048]
As described above, during the period in which the pressure control valve lift amount is fixed to L2 (time T2 to time T3 in FIG. 5, time T2 to time T3, time T7 to time T8 in FIG. 6), from the pressure control chamber 4 The flow of fuel to the pressure control valve chamber 7 is allowed, and the flow of fuel from the pressure control valve chamber 7 to the low pressure fuel leak passage 13 is allowed, so that the fuel in the pressure control chamber 4 passes through the second passage. 11 and the pressure control valve chamber 7 are discharged into the low-pressure fuel leak passage 13 to reduce the pressure in the pressure control chamber 4. Therefore, the sum of the hydraulic pressure (fuel pressure) in the pressure control chamber 4 that biases the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2) and the spring pressure of the spring 8 opens the needle valve 2. The hydraulic pressure in the fuel sump chamber 3 urged toward the valve side (the upper side in FIGS. 1 and 2) becomes smaller, and as a result, the needle valve 2 is moved to the valve opening side.
[0049]
On the other hand, when the pressure in the high pressure fuel supply passage 8 is low, the pressure in the pressure control valve chamber 7 decreases as the amount of fuel flowing into the pressure control valve chamber 7 through the first passage 9 decreases. As a result, the pressure in the pressure control chamber 4 decreases more quickly, and the lift speed of the needle valve 2 increases. When the fuel temperature is low, the amount of fuel flowing into the pressure control valve chamber 7 via the first passage 9 decreases as the fuel viscosity increases, and the pressure in the pressure control valve chamber 7 decreases. As a result, the pressure in the pressure control chamber 4 decreases more quickly, and the lift speed of the needle valve 2 increases. In the present embodiment, in view of these matters, periods (time T2 to time T3 in FIG. 5, time T2 to time T3, time T7 to time T8 in FIG. 6) for fixing the pressure control valve lift amount to L2 are set. . Specifically, when the pressure in the high-pressure fuel supply passage 8 is low, the period during which the pressure control valve lift amount is fixed to L2 is shortened in consideration of an increase in the lift speed of the needle valve 2. In addition, when the fuel temperature is low, considering that the lift speed of the needle valve 2 increases, the period for fixing the pressure control valve lift amount to L2 is shortened.
[0050]
Further, when the throttle degree of the throttle portion 10 of the first passage 9 is stronger than the designed throttle degree, the amount of fuel flowing into the pressure control valve chamber 7 through the first passage 9 decreases. As a result, the pressure in the pressure control valve chamber 7 decreases more rapidly. As a result, the pressure in the pressure control chamber 4 decreases more quickly, and the lift speed of the needle valve 2 increases. On the other hand, when the throttle degree of the throttle portion 10 of the first passage 9 is weaker than the designed throttle degree, the amount of fuel flowing into the pressure control valve chamber 7 through the first passage 9 increases. As a result, the pressure drop in the pressure control valve chamber 7 is delayed, and as a result, the pressure drop in the pressure control chamber 4 is delayed and the lift speed of the needle valve 2 is reduced. In the present embodiment, in view of these matters, the period during which the pressure control valve lift amount is fixed to L2 (time T2 to time T3 in FIG. 5, time T2 to time T3 in FIG. 6, time T7 to time T8) is the fuel injection. It is corrected in the evaluation stage of the device. More specifically, the lift amount of the pressure control valve is fixed at L2 in consideration of an increase in the lift speed of the needle valve 2 when the throttle degree of the throttle portion 10 of the first passage 9 is stronger than the designed throttle degree. The period is shortened. On the other hand, when the throttle degree of the throttle part 10 of the first passage 9 is weaker than the designed throttle degree, the period during which the lift amount of the pressure control valve is fixed to L2 is taken into consideration that the lift speed of the needle valve 2 decreases. Made longer.
[0051]
In this embodiment, a lift amount sensor (not shown) for detecting the needle valve lift amount is provided. When the needle valve 2 is moved to a predetermined intermediate lift position (needle valve lift amount = L2) by the lift amount sensor and stopped there (time T4 to time T5 in FIG. 5, time in FIG. 6). The actual needle valve lift amount from T4 to time T6) is detected, and the pressure control valve lift amount is fixed to L2 based on the difference between the value and the required needle valve lift amount (= NLlow) at that time (FIG. 5). , Feedback correction is performed from time T2 to time T3) in FIG. Specifically, when the detected actual needle valve lift amount is smaller than the required needle valve lift amount (= NLlow), the period during which the pressure control valve lift amount is fixed at L2 (time T2 in FIGS. 5 and 6). ~ Time T3) is lengthened. On the other hand, when the detected actual needle valve lift amount is larger than the required needle valve lift amount (= NLlow), a period during which the pressure control valve lift amount is fixed at L2 (time T2 to time in FIGS. 5 and 6). T3) is shortened. This feedback correction may be executed every time the needle valve 2 is moved to the intermediate lift position, or may be executed periodically at a predetermined time interval.
[0052]
According to this embodiment, the pressure in the pressure control chamber 4 that biases the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2) is controlled by the pressure control valve 6. Therefore, by disposing the pressure control valve at the first position (FIG. 3A) or the second position (FIG. 3B) and increasing or decreasing the pressure in the pressure control chamber 4, the needle valve 2 is The force urging the valve closing side (the lower side in FIGS. 1 and 2) can be increased or decreased. Therefore, even if the pressure in the high-pressure fuel supply passage 8 is not increased, the pressure control valve 6 is arranged at the second position (FIG. 3B), and the pressure in the pressure control chamber 4 is decreased to reduce the needle. The needle valve 2 is moved from the fully closed position to the intermediate lift position (needle valve lift amount = NLlow) by reducing the force that biases the valve 2 toward the valve closing side (the lower side of FIGS. 1 and 2). Can do.
[0053]
Furthermore, according to the present embodiment, the pressure control chamber 4 can be sealed by the pressure control valve 6 when the pressure control valve is disposed at the third position (FIG. 4A). Therefore, the needle valve 2 can be held by the sealed pressure control chamber 4. Therefore, the needle valve 2 can be substantially stopped at any desired lift position between the fully open position and the fully closed position without finely adjusting the pressure in the high pressure fuel supply passage 8. That is, the fuel injection rate can be switched to a desired fuel injection rate by moving the needle valve 2 to a desired intermediate lift position (needle valve lift amount = NLlow) and substantially stopping there.
[0054]
Further, according to the present embodiment, as shown in FIG. 5, when the needle valve 2 is moved from the fully closed position to a predetermined intermediate lift position (needle valve lift amount = NLlow), the needle valve 2 is moved to the predetermined intermediate position. In order to continue to move toward the lift position, the pressure control valve lift amount is fixed to a predetermined value L2 smaller than the maximum value Lmax (= L3) (time T2 to time T3). Therefore, while the needle valve 2 is being moved from the fully closed position to a predetermined intermediate lift position (needle valve lift amount = NLlow) (time T1 to time T4), the pressure control valve lift amount is the maximum value Lmax (= L3). ) To the third mode (FIG. 4A), the needle valve 2 is stopped, and as a result, the needle valve 2 is stopped. It is possible to avoid that 2 cannot lift to the predetermined intermediate lift position (needle valve lift amount = NLlow).
[0055]
Furthermore, according to the present embodiment, as shown in FIG. 6, when the needle valve 2 is moved from the intermediate lift position (needle valve lift amount = NLlow) to the fully open position (needle valve lift amount = NLhigh), the needle valve 2 Is kept at a predetermined value L2 that is larger than zero (time T7 to time T8). Therefore, while the needle valve 2 is being moved from the intermediate lift position (needle valve lift amount = NLlow) to the fully open position (needle valve lift amount = NLhigh) (time T6 to time T9), the pressure control valve lift amount is zero. The second mode (FIG. 3B) is switched to the first mode (FIG. 3A) and the needle valve 2 starts to move toward the fully closed position. As a result, it is possible to avoid the needle valve 2 from being lifted to the fully open position (needle valve lift amount = NLhigh).
[0056]
Furthermore, according to the present embodiment, the pressure in the pressure control chamber 4 that changes in accordance with the pressure control valve lift amount further changes in accordance with the pressure in the high-pressure fuel supply passage 8 and the fuel temperature. In order to control the pressure in the pressure control chamber 4 as required, the pressure control valve lift amount is fixed (time T2 to time T3 in FIG. 5, time T2 to time T3 in FIG. 6, time T7 to time T8 in FIG. ) Is controlled based on the pressure in the high-pressure fuel supply passage 8 and the fuel temperature. Therefore, the pressure in the pressure control chamber 4 can be controlled as required.
[0057]
Furthermore, according to the present embodiment, in view of the fact that the pressure in the pressure control chamber 4 that changes according to the pressure control valve lift amount also changes according to the fuel flow rate that passes through the first passage 9. In order to control the pressure in the control chamber 4 as required, periods (time T2 to time T3 in FIG. 5, time T2 to time T3 in FIG. 6, time T7 to time T8 in FIG. 6) are fixed. Correction is performed based on the flow rate of fuel passing through the first passage 9. Therefore, the pressure in the pressure control chamber 4 can be controlled as required more accurately than when correction is not performed.
[0058]
Furthermore, according to the present embodiment, the difference between the actual needle valve lift amount when the needle valve 2 is moved to a predetermined intermediate lift position (needle valve lift amount = NLlow) and the required needle valve lift amount NLlow at that time. Based on the above, the period during which the pressure control valve lift amount is fixed (time T2 to time T3 in FIG. 5, time T2 to time T3 in FIG. 6) is feedback-corrected. Therefore, the needle valve lift amount can be controlled as required more accurately than when feedback correction is not performed.
[0059]
Hereinafter, a second embodiment of the fuel injection device of the present invention will be described. The configuration of this embodiment is the same as the configuration of the first embodiment described above except for the points described below. Therefore, the same effects as those of the first embodiment can be obtained except for points described later.
[0060]
FIG. 8 is a view showing a pressure control valve control method for executing fuel injection with the fuel injection rate kept low by maintaining the needle valve at an intermediate lift position between the fully open position and the fully closed position. As shown in FIG. 8, in order to execute fuel injection with a low fuel injection rate (fuel injection rate = IRlow), the needle valve 2 is moved from the fully closed position to a predetermined intermediate lift position (needle valve lift amount = NLlow). When it is required to move (time T1), an increase in the voltage applied to the piezoelectric actuator 14 is started, and the pressure control valve lift amount is increased from zero. When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes larger than L4), the needle valve 2 starts to move toward the valve opening side.
[0061]
In this case, the pressure control valve lift is set so that the pressure control valve lift amount does not increase to the maximum value Lmax (= L3) before the needle valve 2 moves to a predetermined intermediate lift position (needle valve lift amount = NLlow). The increasing rate of the quantity is set to a relatively low speed (time T1 to time T4). That is, the increasing speed of the applied voltage to the piezoelectric actuator 14 is set to be relatively low. Specifically, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the pressure control valve is set so that the needle valve 2 reaches a predetermined intermediate lift position (needle valve lift amount = NLlow). The increasing speed of the lift amount is set.
[0062]
Next, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the needle valve 2 is almost stopped at a predetermined intermediate lift position (needle valve lift amount = NLlow). Further, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the increase of the applied voltage to the piezo actuator 14 is stopped. Next, when it is required to move the needle valve 2 from the predetermined intermediate lift position (needle valve lift amount = NLlow) to the fully closed position in order to end the fuel injection (time T5), the application to the piezo actuator 14 is performed. The voltage starts to decrease and the pressure control valve lift amount is reduced to zero.
[0063]
FIG. 9 shows that the needle valve is maintained at an intermediate lift position between the fully open position and the fully closed position at the beginning of the fuel injection period to perform fuel injection with a low fuel injection rate, and during the remaining fuel injection period, the needle valve It is the figure which showed the pressure control valve control method for performing the fuel injection which has arrange | positioned in the fully open position and made the fuel injection rate high. As shown in FIG. 9, the needle valve 2 is moved from the fully closed position to a predetermined intermediate lift position (needle valve lift) in order to execute fuel injection (fuel injection rate = IRlow) with a low fuel injection rate at the beginning of the fuel injection period. When it is required to move to (amount = NLlow) (time T1), an increase in the applied voltage to the piezo actuator 14 is started, and the pressure control valve lift amount is increased from zero. When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes larger than L4), the needle valve 2 starts to move toward the valve opening side.
[0064]
In this case, the pressure control valve lift is set so that the pressure control valve lift amount does not increase to the maximum value Lmax (= L3) before the needle valve 2 moves to a predetermined intermediate lift position (needle valve lift amount = NLlow). The increasing rate of the quantity is set to a relatively low speed (time T1 to time T4). That is, the increasing speed of the applied voltage to the piezoelectric actuator 14 is set to be relatively low. Specifically, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the pressure control valve is set so that the needle valve 2 reaches a predetermined intermediate lift position (needle valve lift amount = NLlow). The increasing speed of the lift amount is set. Next, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the needle valve 2 is almost stopped at the predetermined intermediate lift position (needle valve lift amount = NLlow), and the fuel injection rate is kept low. Fuel injection (fuel injection rate = IRlow) is executed. Further, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the increase of the applied voltage to the piezo actuator 14 is stopped.
[0065]
Next, the needle valve 2 is moved from the predetermined intermediate lift position (needle valve lift amount = NLlow) to the fully open position (needle valve lift amount = NLhigh) in order to execute fuel injection with increased fuel injection rate (fuel injection rate = IRhigh). Is required (time T6), a decrease in the applied voltage to the piezo actuator 14 is started, and the pressure control valve lift amount is decreased from L3 (= Lmax). When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes smaller than L3 (= Lmax)) (after time T6), the needle valve 2 starts moving again to the valve opening side.
[0066]
In such a case, the pressure control valve lift amount decreases relatively slowly so that the pressure control valve lift amount does not decrease to zero before the needle valve 2 moves to the fully open position (needle valve lift amount = NL high). It is set (time T6 to time T9). That is, the decreasing speed of the applied voltage to the piezo actuator 14 is set to be relatively low. When the needle valve 2 hits the fully open position (needle valve lift amount = NLhigh), fuel injection with a higher fuel injection rate (fuel injection rate = IRhigh) is executed. Next, when the pressure control valve lift amount decreases to zero (time T9), the needle valve 2 starts to move toward the fully closed position. The decreasing speed of the pressure control valve lift amount is set so that the pressure control valve lift amount becomes zero when the needle valve 2 should start moving toward the fully closed position (time T9).
[0067]
The pressure control valve control method of the present embodiment for executing fuel injection with a high fuel injection rate (fuel injection rate = IRhigh) from the beginning of the fuel injection period is the pressure control valve control of the first embodiment shown in FIG. The method is similar.
[0068]
As described above, during the period in which the pressure control valve lift amount is increased (time T1 to time T4 in FIGS. 8 and 9) and during the period in which the pressure control valve lift amount is decreased (time T6 in FIG. 9). ~ Time T9), the flow of fuel from the pressure control chamber 4 to the pressure control valve chamber 7 is allowed, and the flow of fuel from the pressure control valve chamber 7 to the low pressure fuel leak passage 13 is allowed to The fuel in the control chamber 4 is discharged into the low-pressure fuel leak passage 13 through the second passage 11 and the pressure control valve chamber 7, and the pressure in the pressure control chamber 4 is reduced. Therefore, the sum of the hydraulic pressure (fuel pressure) in the pressure control chamber 4 that biases the needle valve 2 toward the valve closing side (the lower side in FIGS. 1 and 2) and the spring pressure of the spring 8 opens the needle valve 2. The hydraulic pressure in the fuel sump chamber 3 urged toward the valve side (the upper side in FIGS. 1 and 2) becomes smaller, and as a result, the needle valve 2 is moved to the valve opening side.
[0069]
On the other hand, when the pressure in the high pressure fuel supply passage 8 is low, the pressure in the pressure control valve chamber 7 decreases as the amount of fuel flowing into the pressure control valve chamber 7 through the first passage 9 decreases. As a result, the pressure in the pressure control chamber 4 decreases more quickly, and the lift speed of the needle valve 2 increases. When the fuel temperature is low, the amount of fuel flowing into the pressure control valve chamber 7 via the first passage 9 decreases as the fuel viscosity increases, and the pressure in the pressure control valve chamber 7 decreases. As a result, the pressure in the pressure control chamber 4 decreases more quickly, and the lift speed of the needle valve 2 increases. In this embodiment, in view of these matters, the increasing speed of the pressure control valve lift amount (time T1 to time T4 in FIGS. 8 and 9) and the decreasing speed of the pressure control valve lift amount (time T6 to time T9 in FIG. 9). Is set. Specifically, considering that the lift speed of the needle valve 2 increases when the pressure in the high-pressure fuel supply passage 8 is low, the increase speed of the pressure control valve lift amount (time T1 to time T4 in FIGS. 8 and 9). ) And the decrease rate of the pressure control valve lift amount (time T6 to time T9 in FIG. 9) are set to a relatively high speed. Further, considering that the lift speed of the needle valve 2 increases when the fuel temperature is low, the increase speed of the pressure control valve lift amount (time T1 to time T4 in FIGS. 8 and 9) and the pressure control valve lift amount The decreasing speed (time T6 to time T9 in FIG. 9) is set to a relatively high speed.
[0070]
Further, when the throttle degree of the throttle portion 10 of the first passage 9 is stronger than the designed throttle degree, the amount of fuel flowing into the pressure control valve chamber 7 through the first passage 9 decreases. As a result, the pressure in the pressure control valve chamber 7 decreases more rapidly. As a result, the pressure in the pressure control chamber 4 decreases more quickly, and the lift speed of the needle valve 2 increases. On the other hand, when the throttle degree of the throttle portion 10 of the first passage 9 is weaker than the designed throttle degree, the amount of fuel flowing into the pressure control valve chamber 7 through the first passage 9 increases. As a result, the pressure drop in the pressure control valve chamber 7 is delayed, and as a result, the pressure drop in the pressure control chamber 4 is delayed and the lift speed of the needle valve 2 is reduced. In this embodiment, in view of these matters, the increasing speed of the pressure control valve lift amount (time T1 to time T4 in FIGS. 8 and 9) and the decreasing speed of the pressure control valve lift amount (time T6 to time T9 in FIG. 9). Is corrected in the evaluation stage of the fuel injection device. Specifically, in consideration of the increase in the lift speed of the needle valve 2 when the throttle degree of the throttle portion 10 of the first passage 9 is stronger than the designed throttle degree, the increasing speed of the pressure control valve lift amount (see FIG. 8, the time T1 to time T4 in FIG. 9 and the decrease rate of the pressure control valve lift amount (time T6 to time T9 in FIG. 9) are corrected to the high speed side. On the other hand, when the throttle degree of the throttle portion 10 of the first passage 9 is weaker than the designed throttle degree, considering that the lift speed of the needle valve 2 decreases, the increasing speed of the pressure control valve lift amount (FIG. 8, The time T1 to time T4 in FIG. 9 and the rate of decrease in the pressure control valve lift amount (time T6 to time T9 in FIG. 9) are corrected to the low speed side.
[0071]
In this embodiment, as in the first embodiment, a lift amount sensor (not shown) for detecting the needle valve lift amount is provided. When the needle valve 2 is moved to a predetermined intermediate lift position (needle valve lift amount = L2) by the lift amount sensor and stopped there (time T4 to time T5 in FIG. 8, time in FIG. 9). The actual needle valve lift amount from T4 to time T6) is detected, and the increase rate of the pressure control valve lift amount (FIGS. 8 and 9) based on the difference between the value and the required needle valve lift amount (= NLlow) at that time. Time T1 to time T4) and the pressure control valve lift amount decreasing rate (time T6 to time T9 in FIG. 9) are feedback-corrected. Specifically, when the detected actual needle valve lift amount is smaller than the required needle valve lift amount (= NLlow), the increasing speed of the pressure control valve lift amount (time T1 to time T4 in FIGS. 8 and 9). ) And the decrease rate of the pressure control valve lift amount (time T6 to time T9 in FIG. 9) are corrected to the low speed side. On the other hand, when the detected actual needle valve lift amount is larger than the required needle valve lift amount (= NLlow), the increasing speed of the pressure control valve lift amount (time T1 to time T4 in FIGS. 8 and 9) and The decreasing speed of the pressure control valve lift amount (time T6 to time T9 in FIG. 9) is corrected to the high speed side. This feedback correction may be executed every time the needle valve 2 is moved to the intermediate lift position, or may be executed periodically at a predetermined time interval.
[0072]
According to the present embodiment, when the needle valve 2 is moved from the fully closed position to a predetermined intermediate lift position (needle valve lift amount = NLlow), the pressure control is performed before the needle valve 2 moves to the predetermined intermediate lift position. The increasing speed of the pressure control valve lift amount is set to a relatively low speed so that the valve lift amount does not increase to the maximum value Lmax (= L3) (time T1 to time T4 in FIGS. 8 and 9). Therefore, while the needle valve 2 is being moved from the fully closed position to a predetermined intermediate lift position (needle valve lift amount = NLlow) (time T1 to time T4 in FIGS. 8 and 9), the pressure control valve lift amount is As it increases to the maximum value Lmax (= L3), the second mode (FIG. 3 (B)) is switched to the third mode (FIG. 4 (A)), and the needle valve 2 is stopped. As a result, it is possible to avoid the needle valve 2 from being lifted to the predetermined intermediate lift position.
[0073]
Furthermore, according to the present embodiment, when the needle valve 2 is moved from the intermediate lift position (needle valve lift amount = NLlow) to the fully open position (needle valve lift amount = NLhigh), before the needle valve 2 moves to the fully open position. The reduction speed of the pressure control valve lift amount is set to a relatively low speed so that the pressure control valve lift amount does not decrease to zero (time T6 to time T9 in FIG. 9). Therefore, while the needle valve 2 is being moved from the intermediate lift position (needle valve lift amount = NLlow) to the fully open position (needle valve lift amount = NLhigh) (time T6 to time T9 in FIG. 9), the pressure control valve lift As the amount decreases to zero, the second mode (FIG. 3B) is switched to the first mode (FIG. 3A), and the needle valve 2 begins to move toward the fully closed position. As a result, it can be avoided that the needle valve 2 cannot be lifted to the fully open position.
[0074]
In addition, according to the present embodiment, the pressure in the pressure control chamber 4 that changes in accordance with the pressure control valve lift amount further changes in accordance with the pressure in the high-pressure fuel supply passage 8 and the fuel temperature. In order to control the pressure in the pressure control chamber 4 as required, the pressure control valve lift amount increases (time T1 to time T4 in FIGS. 8 and 9) or the pressure control valve lift amount decreases (FIG. 9). Are controlled on the basis of the pressure in the high-pressure fuel supply passage 8 and the fuel temperature. Therefore, the pressure in the pressure control chamber 4 can be controlled as required.
[0075]
Furthermore, according to the present embodiment, in view of the fact that the pressure in the pressure control chamber 4 that changes according to the pressure control valve lift amount also changes according to the fuel flow rate that passes through the first passage 9. In order to control the pressure in the control chamber 4 as required, the pressure control valve lift amount increases (time T1 to time T4 in FIGS. 8 and 9) or the pressure control valve lift amount decreases (time in FIG. 9). T6 to time T9) are corrected based on the fuel flow rate passing through the first passage 9. Therefore, the pressure in the pressure control chamber 4 can be controlled as required more accurately than when correction is not performed.
[0076]
Furthermore, according to this embodiment, when the needle valve 2 is moved to a predetermined intermediate lift position (time T4 to time T5 in FIG. 8, time T4 to time T6 in FIG. 9), Based on the difference from the required needle valve lift amount NLlow at that time, the increasing speed of the pressure control valve lift amount (time T1 to time T4 in FIGS. 8 and 9) or the decreasing speed of the pressure control valve lift amount (time in FIG. 9). T6 to time T9) are feedback corrected. Therefore, the needle valve lift amount can be controlled as required more accurately than when feedback correction is not performed.
[0077]
Hereinafter, a third embodiment of the fuel injection device of the present invention will be described. The configuration of the present embodiment is the same as the configurations of the first and second embodiments described above except for the points described below. Therefore, the same effects as those of the first and second embodiments can be obtained except for points described below. Also in this embodiment, a lift amount sensor (not shown) for detecting the needle valve lift amount is provided.
[0078]
FIG. 10 shows that the needle valve is maintained at an intermediate lift position between the fully open position and the fully closed position at the beginning of the fuel injection period to perform fuel injection with a low fuel injection rate, and the needle valve is used during the remaining fuel injection period. It is the figure which showed the pressure control valve control method for performing the fuel injection which has arrange | positioned in the fully open position and made the fuel injection rate high. As shown in FIG. 10, the needle valve 2 is moved from the fully closed position to a predetermined intermediate lift position (needle valve lift) in order to execute fuel injection (fuel injection rate = IRlow) with a low fuel injection rate at the beginning of the fuel injection period. When it is required to move to (amount = NLlow) (time T1), an increase in the applied voltage to the piezo actuator 14 is started, and the pressure control valve lift amount is increased from zero. When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes larger than L4) (time T2), the needle valve 2 starts to move toward the valve opening side.
[0079]
Next, in order to continue moving the needle valve 2 toward a predetermined intermediate lift position (needle valve lift amount = NLlow), the pressure control valve lift amount is fixed at L2 (time T2 to time T3). Next, when it is necessary to increase the pressure control valve lift amount again (time T3) in order to substantially stop the needle valve 2 at the predetermined intermediate lift position (needle valve lift amount = NLlow), the piezoelectric actuator 14 is The increase of the applied voltage is started again, and the pressure control valve lift amount is increased again. The time T3 is set so that the needle valve 2 reaches a predetermined intermediate lift position (needle valve lift amount = NLlow) when the pressure control valve lift amount becomes L3 (= Lmax) (time T4). . Next, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the needle valve 2 is almost stopped at the predetermined intermediate lift position (needle valve lift amount = NLlow), and the fuel injection rate is kept low. Fuel injection (fuel injection rate = IRlow) is executed. Further, when the pressure control valve lift amount becomes L3 (= Lmax) (time T4), the increase of the applied voltage to the piezo actuator 14 is stopped.
[0080]
Next, the needle valve 2 is moved from the predetermined intermediate lift position (needle valve lift amount = NLlow) to the fully open position (needle valve lift amount = NLhigh) in order to execute fuel injection with increased fuel injection rate (fuel injection rate = IRhigh). Is required (time T6), a decrease in the applied voltage to the piezo actuator 14 is started, and the pressure control valve lift amount is decreased from L3 (= Lmax). When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes smaller than L3 (= Lmax)) (after time T6), the needle valve 2 starts to move again toward the valve opening side.
[0081]
Next, in order to keep the needle valve 2 moving toward the fully open position (needle valve lift amount = NLhigh), the pressure control valve lift amount is fixed at L2 (time T7 to time T8 ′). When the needle valve 2 hits the fully open position (needle valve lift amount = NLhigh), fuel injection with a higher fuel injection rate (fuel injection rate = IRhigh) is executed. When the lift amount sensor detects that the needle valve 2 has hit the fully open position (needle valve lift amount = NLhigh) (time T8 ′), the pressure control valve lift amount is decreased to L4, and the pressure control valve 6 is Arranged at the fourth position (FIG. 4B). Next, when it is required to move the needle valve 2 from the fully open position (needle valve lift amount = NLhigh) to end the fuel injection, the decrease in the applied voltage to the piezo actuator 14 is started again. The lift amount of the pressure control valve is reduced to zero. Next, when the pressure control valve lift amount decreases to zero (time T9), the needle valve 2 starts to move toward the fully closed position. When the needle valve 2 should start moving toward the fully closed position (time T9), the timing at which the decrease in the applied voltage to the piezo actuator 14 is started again is set so that the pressure control valve lift amount becomes zero. Yes.
[0082]
FIG. 11 is a view showing a pressure control valve control method for executing fuel injection with a high fuel injection rate from the beginning of the fuel injection period. As shown in FIG. 11, the needle valve 2 can be moved from the fully closed position to the fully open position (needle valve lift amount = NLhigh) in order to execute fuel injection with a high fuel injection rate (fuel injection rate = IRhigh). When requested (time T1), an increase in the applied voltage to the piezoelectric actuator 14 is started, and the pressure control valve lift amount is increased from zero. When the pressure control valve lift amount becomes L2 (specifically, when the pressure control valve lift amount becomes larger than L4) (time T2), the needle valve 2 starts to move toward the valve opening side.
[0083]
Next, in order to continue to move the needle valve 2 toward the fully open position (needle valve lift amount = NLhigh), the pressure control valve lift amount is fixed at L2 (time T2 to time T8 ″). When it hits the fully open position (needle valve lift amount = NLhigh), fuel injection with a higher fuel injection rate (fuel injection rate = IRhigh) is executed, and the needle valve 2 is in the fully open position (needle valve lift amount = NLhigh). ) Is detected by the lift amount sensor (time T8 ″), the pressure control valve lift amount is reduced to L4, and the pressure control valve 6 is disposed at the fourth position (FIG. 4B). Is done. Next, when it is required to move the needle valve 2 from the fully open position (needle valve lift amount = NLhigh) to end the fuel injection, the decrease in the applied voltage to the piezo actuator 14 is started again. The lift amount of the pressure control valve is reduced to zero. Next, when the pressure control valve lift amount decreases to zero (time T9), the needle valve 2 starts to move toward the fully closed position. When the needle valve 2 should start moving toward the fully closed position (time T9), the timing at which the decrease in the applied voltage to the piezo actuator 14 is started again is set so that the pressure control valve lift amount becomes zero. Yes.
[0084]
According to the present embodiment, when the needle valve 2 is located at the fully open position (needle valve lift amount = NLhigh) (time T8 ′ to time T9 in FIG. 10, time T8 ″ to time T9 in FIG. 11), A fourth position where the pressure control valve lift amount is smaller than the pressure control valve lift amount in the second mode (FIG. 3B) and the third mode (FIG. 4A) (FIG. 4B). )), The pressure control valve 6 is arranged, so that when the needle valve 2 is in the fully open position, the pressure control valve is arranged in the second position or in the third position. In comparison, it is possible to reduce the amount of fuel discharged into the low-pressure fuel leak passage 13. Therefore, the fuel temperature rises as high-pressure fuel is discharged into the low-pressure fuel leak passage 13. Can be suppressed.
[0085]
Furthermore, according to the present embodiment, as soon as the needle valve 2 moves to the fully open position (needle valve lift amount = NLhigh), the pressure control valve 6 is immediately moved from the second position (FIG. 3B) to the fourth position (FIG. 3). 4 (B)) (time T8 ′ in FIG. 10, time T8 ″ in FIG. 11). Therefore, the amount of fuel discharged into the low-pressure fuel leak passage 13 can be minimized.
[0086]
【The invention's effect】
According to the first aspect of the present invention, the pressure control valve is disposed at the first position or the second position, and the pressure in the pressure control chamber is increased or decreased to bias the nozzle hole opening / closing valve toward the valve closing side. The power to do can be increased or decreased. Therefore, even if the pressure in the high pressure fuel supply passage is not increased, the pressure control valve is disposed at the second position, the pressure in the pressure control chamber is decreased, and the nozzle hole opening / closing valve is biased toward the valve closing side. By reducing the force, the nozzle hole opening / closing valve can be moved from the fully closed position to the intermediate lift position. Further, the nozzle hole opening / closing valve can be held by the sealed pressure control chamber. Therefore, the injection hole on-off valve can be substantially stopped at any desired lift position between the fully open position and the fully closed position without finely adjusting the pressure in the high pressure fuel supply passage. That is, the fuel injection rate can be switched to the desired fuel injection rate by moving the injection hole opening / closing valve to the desired intermediate lift position and substantially stopping there.
[0088]
Claim 1 In the second mode, the pressure control valve lift amount increases to the maximum value while the nozzle hole opening / closing valve is moved from the fully closed position to the predetermined intermediate lift position. Therefore, it is possible to prevent the nozzle hole opening / closing valve from being switched to the third mode and stopped so that the nozzle hole opening / closing valve cannot be lifted to the predetermined intermediate lift position.
[0090]
Claim 2 According to the invention described in the second mode, the first mode is changed from the second mode as the pressure control valve lift amount decreases to zero while the nozzle hole opening / closing valve is moved from the intermediate lift position to the fully open position. Thus, the nozzle hole opening / closing valve starts to move toward the fully closed position, and as a result, the nozzle hole opening / closing valve cannot be lifted to the fully open position.
[0093]
Claim 3 According to the invention described in (1), the pressure in the pressure control chamber can be controlled as required.
[0094]
Claim 4 According to the invention described in Than Exactly, the pressure in the pressure control chamber can be controlled as required.
[0095]
Claim 5 According to the invention described in (1), the injection hole opening / closing valve lift amount can be controlled as required more accurately than when feedback correction is not performed.
[0096]
Claim 6 According to the invention described in (4), the low pressure fuel leak is compared with the case where the pressure control valve is arranged at the second position or the third position when the nozzle hole on-off valve is located at the fully open position. The amount of fuel discharged into the passage can be reduced. Therefore, it is possible to suppress the fuel temperature from rising as the high pressure fuel is discharged into the low pressure fuel leak passage.
[0097]
Claim 7 According to the invention described in (1), the amount of fuel discharged into the low pressure fuel leak passage can be minimized.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a first embodiment of a fuel injection device of the present invention.
FIG. 2 is an enlarged view of a part of FIG. 1;
FIG. 3 is a diagram showing a first mode and a second mode of the pressure control valve.
FIG. 4 is a diagram showing a third mode and a fourth mode of the pressure control valve.
FIG. 5 shows a pressure control valve control method for executing fuel injection with the fuel injection rate kept low by maintaining the needle valve in the intermediate lift position between the fully open position and the fully closed position in the first embodiment. FIG.
FIG. 6 performs fuel injection with the fuel injection rate kept low by maintaining the needle valve at an intermediate lift position between the fully open position and the fully closed position at the beginning of the fuel injection period in the first embodiment; It is the figure which showed the pressure control valve control method for performing the fuel injection which arrange | positioned the needle valve in the full open position during the fuel injection period, and made the fuel injection rate high.
FIG. 7 is a view showing a pressure control valve control method for executing fuel injection with a high fuel injection rate from the beginning of the fuel injection period in the first embodiment.
FIG. 8 shows a pressure control valve control method for performing fuel injection with the fuel injection rate kept low by maintaining the needle valve in the intermediate lift position between the fully open position and the fully closed position in the second embodiment. FIG.
FIG. 9 performs fuel injection with the fuel injection rate kept low by maintaining the needle valve at an intermediate lift position between the fully open position and the fully closed position at the beginning of the fuel injection period in the second embodiment; It is the figure which showed the pressure control valve control method for performing the fuel injection which arrange | positioned the needle valve in the full open position during the fuel injection period, and made the fuel injection rate high.
FIG. 10 performs fuel injection with the fuel injection rate kept low by maintaining the needle valve at an intermediate lift position between the fully open position and the fully closed position at the beginning of the fuel injection period in the third embodiment; It is the figure which showed the pressure control valve control method for performing the fuel injection which arrange | positioned the needle valve in the full open position during the fuel injection period, and made the fuel injection rate high.
FIG. 11 is a diagram showing a pressure control valve control method for executing fuel injection with a higher fuel injection rate from the beginning of the fuel injection period in the third embodiment.
[Explanation of symbols]
1 ... Fuel injection hole
2 ... Needle valve
3 ... Fuel storage chamber
4 ... Pressure control room
5 ... Spring
6 ... Pressure control valve
7 ... Pressure control valve chamber
8 ... High pressure fuel supply passage
9 ... First passage
10, 12 ... diaphragm part
11 ... Second passage
13 ... Low pressure fuel leak passage
14 ... Piezo actuator
15 ... hydraulic oil
16 ... Spring

Claims (7)

燃料噴射用噴孔を開閉する噴孔開閉弁と、前記噴孔開閉弁を開弁側に付勢する開弁側付勢手段と、前記噴孔開閉弁を閉弁側に付勢する閉弁側付勢手段とを具備する燃料噴射装置において、前記閉弁側付勢手段が圧力制御室を有し、前記圧力制御室内の圧力を制御するための圧力制御弁を圧力制御弁室内に配置し、高圧燃料供給通路と前記圧力制御弁室とを第一通路によって連通し、前記圧力制御弁室と前記圧力制御室とを第二通路によって連通し、前記圧力制御弁を第一の位置に配置した第一モード時に、前記圧力制御弁室から低圧燃料リーク通路への燃料の流れが遮断されることにより、前記高圧燃料供給通路内の燃料が前記第一通路及び前記第二通路を介して前記圧力制御室内に供給されて前記圧力制御室内の圧力が上昇せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも大きくなって前記噴孔開閉弁が全閉位置に向かって移動せしめられ、前記圧力制御弁を第二の位置に配置した第二モード時に、前記圧力制御室から前記圧力制御弁室への燃料の流れが許容され、かつ、前記圧力制御弁室から前記低圧燃料リーク通路への燃料の流れが許容されることにより、前記圧力制御室内の燃料が前記第二通路及び前記圧力制御弁室を介して前記低圧燃料リーク通路内に排出されて前記圧力制御室内の圧力が低下せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも小さくなって前記噴孔開閉弁が全開位置に向かって移動せしめられ、前記圧力制御弁を第三の位置に配置した第三モード時に、前記圧力制御室と前記圧力制御弁室との間の燃料の流れが遮断されて前記圧力制御室が密閉され、その密閉された圧力制御室によって前記噴孔開閉弁がホールドされることにより、前記噴孔開閉弁が全開位置と全閉位置との間の任意のリフト位置にほぼ停止せしめられるようにし、前記第一モード時には圧力制御弁リフト量がゼロになっており、前記第三モード時には圧力制御弁リフト量が最大値になっており、前記第二モード時には圧力制御弁リフト量がそれらの間の値になっており、前記噴孔開閉弁を全閉位置から所定の中間リフト位置まで移動させることが要求されるとき、圧力制御弁リフト量をゼロから増加させて前記噴孔開閉弁の移動を開始させると共に、前記噴孔開閉弁が前記所定の中間リフト位置まで移動する前に圧力制御弁リフト量が最大値まで増加してしまわないように圧力制御弁リフト量の増加速度を設定し、次いで前記噴孔開閉弁が前記所定の中間リフト位置まで移動した時に圧力制御弁リフト量を最大値に固定することにより、前記噴孔開閉弁を前記所定の中間リフト位置にほぼ停止させるようにした燃料噴射装置。A nozzle opening / closing valve that opens and closes the fuel injection nozzle hole, a valve opening side biasing means that biases the nozzle hole opening / closing valve toward the valve opening side, and a valve closing valve that biases the nozzle hole opening / closing valve toward the valve closing side. In the fuel injection device comprising the side biasing means, the valve closing side biasing means has a pressure control chamber, and a pressure control valve for controlling the pressure in the pressure control chamber is disposed in the pressure control valve chamber. The high pressure fuel supply passage and the pressure control valve chamber communicate with each other through a first passage, the pressure control valve chamber and the pressure control chamber communicate with each other through a second passage, and the pressure control valve is disposed at a first position. In the first mode, the flow of fuel from the pressure control valve chamber to the low pressure fuel leak passage is blocked, so that the fuel in the high pressure fuel supply passage passes through the first passage and the second passage. The pressure is supplied to the pressure control chamber and the pressure in the pressure control chamber is increased. As a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is greater than the force for urging the nozzle hole opening / closing valve toward the valve opening side, causing the nozzle hole opening / closing valve to move toward the fully closed position. In the second mode in which the pressure control valve is disposed at the second position, the flow of fuel from the pressure control chamber to the pressure control valve chamber is allowed, and the low pressure fuel leak from the pressure control valve chamber By allowing the fuel flow to the passage, the fuel in the pressure control chamber is discharged into the low-pressure fuel leak passage through the second passage and the pressure control valve chamber, and the pressure in the pressure control chamber is reduced. As a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is smaller than the force for urging the nozzle hole opening / closing valve toward the valve opening side, so that the nozzle hole opening / closing valve is in the fully opened position. And the pressure control valve is placed in the third position. In the third mode, the flow of fuel between the pressure control chamber and the pressure control valve chamber is shut off, the pressure control chamber is sealed, and the nozzle hole opening / closing valve is held by the sealed pressure control chamber. Thus, the nozzle opening / closing valve can be stopped almost at an arbitrary lift position between the fully open position and the fully closed position, and the pressure control valve lift amount is zero in the first mode, In the third mode, the pressure control valve lift amount is a maximum value. In the second mode, the pressure control valve lift amount is a value between them. When it is required to move to the intermediate lift position, the pressure control valve lift amount is increased from zero to start the movement of the nozzle hole opening / closing valve, and the nozzle hole opening / closing valve moves to the predetermined intermediate lift position. You The pressure control valve lift amount is set so as not to increase to the maximum value before the pressure control valve lift amount is increased, and then the pressure control valve lift amount is controlled when the nozzle opening / closing valve moves to the predetermined intermediate lift position. A fuel injection device configured to substantially stop the nozzle hole opening / closing valve at the predetermined intermediate lift position by fixing a valve lift amount to a maximum value . 前記噴孔開閉弁を全閉位置から所定の中間リフト位置まで移動させ、次いで全開位置まで移動させることが要求されるとき、圧力制御弁リフト量をゼロから増加させて前記噴孔開閉弁の移動を開始させると共に、前記噴孔開閉弁が前記所定の中間リフト位置まで移動する前に圧力制御弁リフト量が最大値まで増加してしまわないように圧力制御弁リフト量の増加速度を設定し、次いで前記噴孔開閉弁が前記所定の中間リフト位置まで移動した時に圧力制御弁リフト量を最大値に固定することにより、前記噴孔開閉弁を前記所定の中間リフト位置にほぼ停止させ、次いで圧力制御弁リフト量を最大値から減少させて前記噴孔開閉弁を全開位置に向かって再び移動させると共に、前記噴孔開閉弁が全開位置まで移動する前に圧力制御弁リフト量がゼロまで減少してしまわないように圧力制御弁リフト量の減少速度を設定し、前記噴孔開閉弁を全開位置まで移動させるようにした請求項１に記載の燃料噴射装置。 When it is required to move the nozzle hole opening / closing valve from the fully closed position to a predetermined intermediate lift position and then to the fully open position, the pressure control valve lift amount is increased from zero to move the nozzle hole opening / closing valve. And increasing the pressure control valve lift amount so that the pressure control valve lift amount does not increase to the maximum value before the nozzle hole opening / closing valve moves to the predetermined intermediate lift position, Next, when the nozzle hole opening / closing valve moves to the predetermined intermediate lift position, the pressure control valve lift amount is fixed to the maximum value, thereby causing the nozzle hole opening / closing valve to substantially stop at the predetermined intermediate lift position, and then the pressure The control valve lift amount is decreased from the maximum value, the nozzle hole opening / closing valve is moved again toward the fully open position, and the pressure control valve lift amount is reduced before the nozzle hole opening / closing valve moves to the fully open position. Set the rate of reduction of the pressure control valve lift amount so as not reduced to B, a fuel injection device according to claim 1 which is adapted to move the nozzle hole closing valve to a fully open position. 圧力制御弁リフト量の増加速度又は圧力制御弁リフト量の減少速度を前記高圧燃料供給通路内の圧力と燃料温度とに基づいて算出するようにした請求項１又は２に記載の燃料噴射装置。 3. The fuel injection device according to claim 1, wherein an increasing speed of the pressure control valve lift amount or a decreasing speed of the pressure control valve lift amount is calculated based on a pressure in the high pressure fuel supply passage and a fuel temperature . 前記第一通路の絞り部の絞り度合に基づいて圧力制御弁リフト量の増加速度又は圧力制御弁リフト量の減少速度を設定するようにした請求項３に記載の燃料噴射装置。 4. The fuel injection device according to claim 3 , wherein an increasing speed of the pressure control valve lift amount or a decreasing speed of the pressure control valve lift amount is set based on a throttle degree of the throttle portion of the first passage . 噴孔開閉弁リフト量を検出するためのリフト量検出手段を設け、前記噴孔開閉弁が前記所定の中間リフト位置まで移動せしめられた時の実際の噴孔開閉弁リフト量とその時の要求噴孔開閉弁リフト量との差分に基づいて、圧力制御弁リフト量を固定 する期間、圧力制御弁リフト量の増加速度、又は圧力制御弁リフト量の減少速度をフィードバック補正するようにした請求項３又は４に記載の燃料噴射装置。 A lift amount detecting means for detecting the lift amount of the nozzle hole opening / closing valve is provided, and the actual nozzle hole opening / closing valve lift amount when the nozzle hole opening / closing valve is moved to the predetermined intermediate lift position and the requested injection at that time. 4. A feedback correction of a period during which the pressure control valve lift amount is fixed, an increasing speed of the pressure control valve lift amount, or a decreasing speed of the pressure control valve lift amount based on a difference from the hole opening / closing valve lift amount. Or the fuel-injection apparatus of 4 . 燃料噴射用噴孔を開閉する噴孔開閉弁と、前記噴孔開閉弁を開弁側に付勢する開弁側付勢手段と、前記噴孔開閉弁を閉弁側に付勢する閉弁側付勢手段とを具備する燃料噴射装置において、前記閉弁側付勢手段が圧力制御室を有し、前記圧力制御室内の圧力を制御するための圧力制御弁を圧力制御弁室内に配置し、高圧燃料供給通路と前記圧力制御弁室とを第一通路によって連通し、前記圧力制御弁室と前記圧力制御室とを第二通路によって連通し、前記圧力制御弁を第一の位置に配置した第一モード時に、前記圧力制御弁室から低圧燃料リーク通路への燃料の流れが遮断されることにより、前記高圧燃料供給通路内の燃料が前記第一通路及び前記第二通路を介して前記圧力制御室内に供給されて前記圧力制御室内の圧力が上昇せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも大きくなって前記噴孔開閉弁が全閉位置に向かって移動せしめられ、前記圧力制御弁を第二の位置に配置した第二モード時に、前記圧力制御室から前記圧力制御弁室への燃料の流れが許容され、かつ、前記圧力制御弁室から前記低圧燃料リーク通路への燃料の流れが許容されることにより、前記圧力制御室内の燃料が前記第二通路及び前記圧力制御弁室を介して前記低圧燃料リーク通路内に排出されて前記圧力制御室内の圧力が低下せしめられ、その結果、前記噴孔開閉弁を閉弁側に付勢する力が前記噴孔開閉弁を開弁側に付勢する力よりも小さくなって前記噴孔開閉弁が全開位置に向かって移動せしめられ、前記圧力制御弁を第三の位置に配置した第三モード時に、前記圧力制御室と前記圧力制御弁室との間の燃料の流れが遮断されて前記圧力制御室が密閉され、その密閉された圧力制御室によって前記噴孔開閉弁がホールドされることにより、前記噴孔開閉弁が全開位置と全閉位置との間の任意のリフト位置にほぼ停止せしめられるようにし、圧力制御弁リフト量が第二モード時及び第三モード時の圧力制御弁リフト量よりも小さくなっている第四の位置に前記圧力制御弁を配置した第四モード時に、前記噴孔開閉弁を閉弁側に付勢する力と前記噴孔開閉弁を開弁側に付勢する力とが等しくなるようにし、前記噴孔開閉弁が全開位置に位置している時に前記圧力制御弁を第四の位置に配置するようにした燃料噴射装置。 A nozzle opening / closing valve that opens and closes the fuel injection nozzle hole, a valve opening side biasing means that biases the nozzle hole opening / closing valve toward the valve opening side, and a valve closing valve that biases the nozzle hole opening / closing valve toward the valve closing side. In the fuel injection device comprising the side biasing means, the valve closing side biasing means has a pressure control chamber, and a pressure control valve for controlling the pressure in the pressure control chamber is disposed in the pressure control valve chamber. The high pressure fuel supply passage and the pressure control valve chamber communicate with each other through a first passage, the pressure control valve chamber and the pressure control chamber communicate with each other through a second passage, and the pressure control valve is disposed at a first position. In the first mode, the flow of fuel from the pressure control valve chamber to the low pressure fuel leak passage is blocked, so that the fuel in the high pressure fuel supply passage passes through the first passage and the second passage. The pressure is supplied to the pressure control chamber and the pressure in the pressure control chamber is increased. As a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is greater than the force for urging the nozzle hole opening / closing valve toward the valve opening side, causing the nozzle hole opening / closing valve to move toward the fully closed position. In the second mode in which the pressure control valve is disposed at the second position, the flow of fuel from the pressure control chamber to the pressure control valve chamber is allowed, and the low pressure fuel leak from the pressure control valve chamber By allowing the fuel flow to the passage, the fuel in the pressure control chamber is discharged into the low-pressure fuel leak passage through the second passage and the pressure control valve chamber, and the pressure in the pressure control chamber is reduced. As a result, the force for urging the nozzle hole opening / closing valve toward the valve closing side is smaller than the force for urging the nozzle hole opening / closing valve toward the valve opening side, so that the nozzle hole opening / closing valve is in the fully opened position. And the pressure control valve is placed in the third position. In the third mode, the flow of fuel between the pressure control chamber and the pressure control valve chamber is shut off, the pressure control chamber is sealed, and the nozzle hole opening / closing valve is held by the sealed pressure control chamber. Thus, the nozzle hole on-off valve can be stopped almost at an arbitrary lift position between the fully open position and the fully closed position, and the pressure control valve lift amount is the pressure control in the second mode and the third mode. In the fourth mode in which the pressure control valve is arranged at a fourth position that is smaller than the valve lift amount, the force for urging the nozzle hole opening / closing valve to the valve closing side and the nozzle hole opening / closing valve to the valve opening side The fuel injection device is arranged such that the pressure control valve is arranged at a fourth position when the nozzle opening / closing valve is located at the fully open position . 噴孔開閉弁リフト量を検出するためのリフト量検出手段を設け、前記噴孔開閉弁が全開位置まで移動したら即座に前記圧力制御弁を第二の位置から第四の位置まで移動させるようにした請求項６に記載の燃料噴射装置。 A lift amount detecting means for detecting the lift amount of the nozzle hole opening / closing valve is provided, and the pressure control valve is moved from the second position to the fourth position as soon as the nozzle hole opening / closing valve moves to the fully open position. injector according to claim 6 in which the.
JP2000260889A 2000-08-25 2000-08-25 Fuel injection device Expired - Fee Related JP3829605B2 (en)

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