JP4078779B2

JP4078779B2 - Fuel injection valve

Info

Publication number: JP4078779B2
Application number: JP2000036678A
Authority: JP
Inventors: 覚佐々木; 正明加藤
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2000-02-15
Filing date: 2000-02-15
Publication date: 2008-04-23
Anticipated expiration: 2020-02-15
Also published as: JP2001227428A

Description

【０００１】
【発明の属する技術分野】
本発明は、段階的に燃料を噴射可能な燃料噴射弁に関する。
【０００２】
【従来の技術】
従来より、ディーゼル機関において低排出物（ＮＯＸ、ＨＣ、黒煙）および高出力、低燃費を両立させるためにエンジンの運転条件に応じて噴射率を可変にすることが必要である。この要件を実現するために、従来技術としてニードルを付勢するように２個のばねを構成した２段開弁圧ノノズルが公知となっている。
【０００３】
しかし、この技術では燃料噴射ポンプから圧送させる燃料圧力はエンジン運転状態によって変動するので、エンジンが要求する噴射率を全運転条件において実現するのは困難である。
【０００４】
そこで、例えば米国特許５，６９４，９０３号に開示されている従来の燃料噴射弁は、ニードルを噴孔閉塞方向に燃料圧力を加える制御室を設けるものがある。これは、ノズル燃料溜りに導入される燃料圧力により噴孔を開放方向に受ける力と制御室の燃料圧力から噴孔閉塞方向に受ける力との大小関係により噴射を制御している。制御室の燃料圧力を制御しているパイロットバルブステムの開口面積を変化させることにより制御室圧力を変化させ、ニードルを段階的にリフトさせて要求の噴射率を得ようとしている。
【０００５】
また、例えば特開平１０−５４３２３号公報に開示されているように、制御室への高圧燃料の入口部と出口部にそれぞれ制御弁を配置し、ニードルリフトを段階的に制御している燃料噴射弁がある。この構成によれば、制御室への入口、出口の開閉制御が独立に制御可能なため、安定したリフト制御およびリーク量は低減できる。
【０００６】
【発明が解決しようとする課題】
しかし、米国特許５，６９４，９０３号に開示されている従来の燃料噴射弁の構成では、制御室の燃料圧力はステムの開口面積、燃料性状、燃料温度等により変化するためニードルのリフトは不安定となり、安定した噴射率制御は困難であった。また、制御室圧力を制御する制御弁に２方弁を用いており、噴射期間中には常に高圧燃料が制御室および排出路を経てリークされ続ける構造となっており燃料ポンプの無駄な仕事が増加し、燃費悪化の原因となっている。
【０００７】
また、特開平１０−５４３２３号公報においては、電磁弁を複数必要なため燃料噴射弁が大型化し、かつ高価格になる。
【０００８】
本発明の目的は上記の点に鑑み、比較的小型の構造でもって、エンジンの全運転状態に応じて要求する噴射率を安定して得られるようにニードルリフトを段階的に制御可能な燃料噴射弁を提供することにある。
【０００９】
【課題を解決するための手段】
上述した課題を解決するために、本発明の請求項１および請求項２記載の燃料噴射弁は、制御弁を構成するバルブ室内の一つの弁体を電気的に駆動する駆動装置により段階的にリフトさせることにより、第１圧力室と連通する第１の開口部と、第２圧力室と連通する第２の開口部と、低圧通路と連通する低圧開口部の内、第１の開口部または低圧開口部を開閉させて、第１圧力室およびまたは第２圧力室の燃料圧力を変化させるように構成した。
【００１０】
上記の燃料噴射弁は、一つの弁体の段階的なリフト作動により第１圧力室および第２圧力室の圧力を変化させて、第１ピストンおよび第２ピストンを段階的にリフトさせる。第１ピストンおよび第２ピストンは弁部材と協働するので、弁部材のリフトを段階的に制御可能である。
【００１１】
このように、一つの弁体よりなる簡潔な構成の制御弁としたことで燃料噴射弁の小型化が可能となり、かつ第１ピストンおよび第２ピストンを段階的にリフトさせて噴射率を可変可能な燃料噴射弁とすることができる。
【００１２】
本発明の請求項３記載の燃料噴射弁は、第１圧力室および第２圧力室の燃料圧力を次の３つのステップにより変化させて第１圧力室と第２圧力室の燃料圧力を制御している。
【００１３】
先ず、バルブ室内の弁体をリフトさせる前では、弁体が低圧開口部を閉塞している。高圧通路の高圧燃料はバルブ室の第２開口部を経てバルブ室内に導かれ、次いでこの高圧燃料は第１開口部より第１圧力室へ連通される。一方、第２圧力室に連通された高圧回路はバルブ室に連通しているものの弁体により低圧開口部を閉塞されている。よって、第１圧力室と第２圧力室の高圧燃料により閉弁方向に第１ピストンおよび第２ピストンを付勢している。弁部材のリフト量に応じ噴孔閉塞方向に弁部材を付勢する付勢手段とあわせて弁部材は、弁座に着座している。
【００１４】
次に、弁体が第１のリフトをすると、弁体が低圧開口部を開放して第１圧力室と第２圧力室内の高圧燃料はバルブ室の低圧開口部を通じて低圧通路と連通される。よって、第１圧力室と第２圧力室の燃料圧力は高圧状態から低圧状態に変化して開弁方向に第１ピストンおよび第２ピストンは次のようにリフトする。
【００１５】
第１ピストンがリフトすると第２ピストンに当接して、第２ピストンがリフトすることで第１ピストンおよび第２ピストンがともにリフトするので、第１ピストンのリフト量と第２ピストンのリフト量とを併せた分だけ弁部材はリフトし、弁部材が弁座から離座して噴孔から燃料が噴射する。
【００１６】
次に、弁体が第１のリフト以上リフトして第２のリフトをすると、第１圧力室はバルブ室を通じて低圧通路と連通されたままなので第１圧力室のみ燃料圧力は高圧状態から低圧状態に変化するとともに、弁体は第２の開口部を閉塞して第２圧力室は低圧通路との連通を遮断する。よって、第２圧力室の燃料圧力は高圧状態を維持して閉弁方向に第２ピストンを付勢している。つまり、第１ピストンがリフトして第２ピストンに当接し第１ピストンのリフト量だけ弁部材はリフトし、弁部材が弁座から離座して噴孔から燃料が噴射する。
【００１７】
このように、一つの弁体よりなる簡潔な構成の制御弁としたことで安価な燃料噴射弁となり、かつ第１ピストンおよび第２ピストンを段階的にリフトさせて噴射率を可変可能な燃料噴射弁とすることができる。
【００１８】
また、弁体が第２のリフトをして第１ピストンのリフト量だけ弁部材がリフトする場合には、高圧回路と低圧回路は第２の開口部を閉鎖することで遮断されるので、高圧燃料を圧送する燃料ポンプの無駄な仕事が抑制されて燃費向上効果がある。
【００１９】
本発明の請求項４記載の燃料噴射弁は、付勢手段は、弁部材のリフト量に関わらず噴孔閉塞方向に弁部材を付勢する第１の付勢手段を備えた。この第１の付勢手段は、第１圧力室と第２圧力室が低圧通路に接続されて第１ピストンおよび第２ピストンの弁部材閉弁方向への付勢力が減少した場合に、弁部材の閉弁方向の付勢力を維持して弁部材が弁座から離座するのを防止する。
【００２０】
一方、弁部材が第１のリフト以上リフトすると噴孔閉塞方向に弁部材を付勢する第２の付勢手段を備えることで、第１ピストンがリフトして第２ピストンに当接し、第１ピストンのリフトによる慣性力が第２ピストンを押し上げることのないように第２ピストンを噴孔閉塞方向に付勢させる。よって、安定した噴射量が得られる燃料噴射弁とすることができる。
【００２１】
本発明の請求項５記載の燃料噴射弁は、弁体が駆動装置側にリフトして低圧開口部を閉塞することで、弁体が駆動装置によりリフト摺動する弁体支持部分が低圧燃料雰囲気にある。よって、弁体支持部分の摺動に必要な隙間部からの燃料リーク量を低減できる。
【００２２】
本発明の請求項６記載の燃料噴射弁は、高圧通路と第２圧力室を連通する通路は、高圧通路を第２の開口部と第２圧力室とを連通する通路に配置された第１絞り部に対して、バルブ室側の位置で接続することで構成されるようにした。
【００２３】
第１圧力室が低圧から高圧に燃料圧力を変化させる場合、高圧燃料は、高圧通路、バルブ室を経て供給されるが、高圧通路から第２圧力室を経由して供給される場合と比較して高圧通路から第２圧力室の間の絞り部が１つ削減できる効果がある。
【００２４】
絞り部が１つ削減できると、第１圧力室への燃料供給がスムーズに行われるために第１圧力室の圧力上昇が早くなる。このために噴孔を閉塞方向に働く力が早く大きくなり弁部材の下降速度が速くできる。つまり、弁部材の閉弁応答性が向上する。
【００２５】
本発明の請求項７記載の燃料噴射弁は、高圧通路と第１圧力室の間に燃料流れを調整する第２の絞り部を介して接続する通路を設けた。
【００２６】
この構成にすると高圧通路から第１圧力室への燃料通路は、バルブ室経由に加えて、上述した高圧通路と第１圧力室の間を接続する通路からも高圧燃料が導入できる。
【００２７】
上記した構成により、弁部材閉弁時の第１圧力室への流入燃料量が増加でき、第１圧力室の圧力上昇を早くできる。このために噴孔を閉塞方向に働く力が早く大きくなり弁部材の下降速度が速くできる。つまり、弁部材の閉弁応答性が向上する。
【００２８】
本発明の請求項８記載の燃料噴射弁は、第１圧力室と第２圧力室の間に燃料流れを調整する第４の絞り部を介して接続する構成とした。
【００２９】
この構成にすると高圧通路から第１圧力室への燃料通路は、バルブ室経由に加えて、上述した第１圧力室と第２圧力室の間を接続する通路からも高圧燃料が導入できる。
【００３０】
上記した構成により、弁部材閉弁時の第１圧力室への流入燃料量が増加でき、第１圧力室の圧力上昇を早くできる。このために噴孔を閉塞方向に働く力が早く大きくなり弁部材の下降速度が速くできる。つまり、弁部材の閉弁応答性が向上する。
【００３１】
本発明の請求項９記載の燃料噴射弁は、バルブ室と第１圧力室とを連通する通路において、バルブ室側に広いテーパ口部を構成した。
【００３２】
このバルブ室側に広いテーパ口部は、バルブ室を経由して高圧燃料が第１圧力室へ導入される時の高圧燃料流れを導き入れ易くなり、第１圧力室が早く高圧化する効果がある。このために噴孔を閉塞方向に働く力が早く大きくなり弁部材の下降速度が速くできる。つまり、弁部材の閉弁応答性が向上する。
【００３３】
本発明の請求項１０記載の燃料噴射弁は、第１の絞り部を廃止して、低圧通路に第３の絞り部を配置することで、第３の絞り部が第１の絞り部に代わって高圧通路と第１圧力室の間の燃料流れを調整する構成とした。
【００３４】
第２圧力室を高圧から低圧に燃料圧力を変化させる場合、第１の絞り部に代わって低圧通路に第３の絞り部を配置変更しても、第３の絞り部は第１の絞り部と同様に第２圧力室から低圧通路の経路にあり、第２圧力室の高圧から低圧に変化する燃料圧力の移行速度を調節している。
【００３５】
一方、高圧通路から第１圧力室への燃料通路に第１の絞り部が無くなったので、弁部材閉弁時の第１圧力室への流入燃料量が増加でき、第１圧力室の圧力上昇を早くできるので弁部材の下降速度を向上させる効果がある。つまり、弁部材の閉弁応答性が向上する。
【００３６】
本発明の請求項１１記載の燃料噴射弁は、制御弁を構成するバルブ室内の一つの弁体を電気的に駆動する駆動装置により段階的にリフトさせることにより、第１圧力室と連通する第１の開口部と、第２圧力室と連通する第２の開口部と、低圧通路と連通する低圧開口部を次の３つのステップにより変化させて第１圧力室と第２圧力室の燃料圧力を制御している。
【００３７】
先ず、バルブ室内の弁体をリフトさせる前では、弁体が低圧開口部を閉塞している。高圧通路の高圧燃料はバルブ室の第２開口部を経てバルブ室内に導かれ、次いで、この高圧燃料は第１開口部より第１圧力室へ連通される。一方、第２圧力室に連通された高圧回路はバルブ室に連通しているものの弁体により低圧開口部を閉塞されている。よって、第１圧力室と第２圧力室の高圧燃料により閉弁方向に第１ピストンおよび第２ピストンを付勢している。弁部材のリフト量に応じ噴孔閉塞方向に弁部材を付勢する付勢手段とあわせて弁部材は、弁座に着座している。
【００３８】
次に、弁体が第１のリフトをすると、弁体が低圧開口部を開放して第１圧力室と第２圧力室内の高圧燃料はバルブ室の低圧開口部を通じて低圧通路と連通される。よって、第１圧力室と第２圧力室の燃料圧力は高圧状態から低圧状態に変化して開弁方向に第１ピストンおよび第２ピストンは次のようにリフトする。
【００３９】
第２ピストンがリフトして係止部材に係止してリフトは規制され、第１ピストンがリフトすると第２ピストンに当接してリフトは規制される。第１ピストンのリフト量と第２ピストンのリフト量とを併せた分だけ弁部材はリフトし、弁部材が弁座から離座して噴孔から燃料が噴射する。
【００４０】
次に、弁体が第１のリフト以上リフトして第２のリフトをすると、第２圧力室はバルブ室を通じて低圧通路と連通されたままなので第２圧力室のみ燃料圧力は高圧状態から低圧状態に変化するとともに、弁体は第１の開口部を閉塞して第１圧力室は低圧通路との連通を遮断する。ここで、第１圧力室は高圧状態を維持するが、第２ピストンが上昇することにより体積変化し、第１圧力室の燃料圧力は低下する。しかし、第１圧力室の圧力は高圧を維持するように高圧燃料を供給調整することで第１ピストンは、第２ピストンの移動量だけ移動する。つまり、第１ピストンのリフト分だけ第１ピストンに第２ピストンが追動して弁部材はリフトし、弁部材が弁座から離座して噴孔から燃料が噴射する。
【００４１】
上記構成にすることにより、弁部材のリフト調整（第２ピストンのリフト量）が容易になる。
【００４２】
本発明の請求項１２記載の燃料噴射弁は、電気的に駆動する駆動装置は、電磁コイルにより前記弁体をリフトする構成とした。電磁コイルにすることで限られた空間に電磁コイルを装着可能で、駆動装置の体格をコンパクトにすることができる。
【００４３】
本発明の請求項１３記載の燃料噴射弁は、請求項１ないし請求項１０のいずれか１項に記載の燃料噴射弁において、電気的に駆動する駆動装置は、ピエゾアクチュエーターにより前記弁体をリフトする構成とした。ピエゾアクチュエーターは電荷を加えることに対する変位応答性が早く、弁部材のリフト応答性の優れる燃料噴射弁とすることができる。
【００４４】
【発明の実施の形態】
以下、本発明の実施形態を示す複数の実施例について図面を参照しながら詳細に説明する。
【００４５】
（第１実施例）
本発明の第１実施例の燃料噴射弁の構成を図１、図２および図３を用いて説明する。図１は、本発明の第１実施例による燃料噴射弁の全体断面図を示す。図２は、図１に示す燃料噴射弁の弁体が第２リフトした状態を示す部分断面図である。図３は、図１に示す燃料噴射弁の弁体が第１リフトした状態を示す部分断面図である。
【００４６】
燃料噴射弁１の構成は、基本的に図１に示すように燃料噴射弁ハウジング１０内に、第１ピストン２１、この第１ピストン２１の上方に第２ピストン２２を配置させ、更に第１ピストン２１と第２ピストン２２の間に第１圧力室５０を形成するとともに、第２ピストン２２の上面に第２圧力室５１を形成したものとなっている。そして、この第１圧力室５０、第２圧力室５１の燃料圧力を第２圧力室５１上方に配設した電磁弁３０により制御することにより、第１ピストン２１の下方側に設けられ、後述する噴孔１１を開閉するニードル２３のリフト量を変化させ、噴射率形状を自由に設定可能にできるものである。
【００４７】
燃料噴射弁１のハウジング１０と、その下方に設けられる弁ボディ１３とは、チップパッキン１４を挟みリテーニングナット１２で締結されている。制御装置２０は、弁ボディ１３下端に形成される噴孔１１側から第１ピストン２１、第１圧力室５０、第２ピストン２２、第２圧力室５１より構成され、制御装置２０の噴孔側には制御装置２０と協働するニードル２３、ロッド２４が配置される。ニードル２３は、弁ボディ１３に往復移動自在に支持されている。更に、ニードル２３を、ロッド２４を介して噴孔１１方向に付勢する第１ニードルスプリング１５が設けられている。
【００４８】
また、ハウジング１０には、図示しないコモンレールと連通する高圧通路６０が形成される。この高圧通路６０は、ハウジング１０、チップパッキン１４、弁ボディ１３内を通り、弁ボディ１３に形成される燃料溜り１６へと連通する。更に、高圧通路６０は、上記第２圧力室５１へ連絡通路６８を経由して連通するよう形成されている。これにより図示しないコモンレールより供給された高圧燃料は、ハウジング１０内の高圧通路６０を介して第２圧力室５１及び弁ボディ１３内の燃料溜り１６へ供給される。更に、第１圧力室５０へは、図２に示すように第２圧力室５１に開口される連絡通路６１、後述のバルブ室６２を介してハウジング１０等に形成される連絡通路６４へ連通され、第２圧力室５１より燃料が供給される構成となっている。
【００４９】
制御弁３０は弁カバー３８内に収容され、ハウジング１０の上部と弁カバー３８間でネジ締結されている。制御弁３０はボディ３１、アーマチャ３２、ストッパー３３、第１スプリング３４、電磁コイル３５、第２スプリング３６、弁体３７、プレート３９、バルブ室６２等で構成されている。
【００５０】
このバルブ室６２は、ボデキ３１内に形成され、アーマチャ３２と接続される弁体３７を収容している。そして、アーマチャ３２の弁体３７との接続部分におけるバルブ室６２の上端面には、上記連絡通路６１と接続する第２開口部６５が開口している。また、バルブ室６２の略中央部の側面には、上記連絡通路６４と接続する第１開口部６６が開口している。更に、バルブ室６２の下端面には、プレート３９が形成される低圧開口部６７が開口している。
【００５１】
なお、この低圧開口部６７は、低圧通路６３に接続されている。この低圧通路６３は、ハウジング１０等に形成され、図示しない燃料タンクへと連通されており、バルブ室６２内の燃料を該燃料タンクへと排出するようになっている。
【００５２】
上記弁体３７は、第１スプリング３４の付勢力によりアーマチャ３２を介して、上記低圧開口部６７に着座可能である。また、弁体３７は、電磁コイル３５の吸引によりアーマチャ３２とともに上方へ移動し、第２開口部６５に着座可能となっている。
【００５３】
図１は、電磁コイル３５に通電をしないで弁体３７は低圧開口部６７に着座し、ニードル２３は第１圧力室５０、第２圧力室５１の燃料圧力、および第１ニードルスプリング１５の付勢力により閉弁方向に付勢され弁座１３Ａに着座した状態を示す。尚、２３ａはニードル２３の肩部を示し、１１ａはハウジング１１の下端面を示す。
【００５４】
次に、弁体３７の上部に位置するアーマチャ３２は、コイル３５に通電することにより発生する励起吸引力により、第１スプリング３４の付勢力に抗し上向きに吸引され弁体３７は第１のリフトをする。この状態を図３に示す。
【００５５】
図３に示すように、弁体が上方にリフトしストッパー３３の下端面まで吸引される。この時、弁体３７には第２スプリング３６の付勢力がかかるため電磁コイル３５からの吸引力と第１スプリング３４と第２スプリング３６の付勢力の和が釣り合うために弁体３７はリフトＨ１（図１参照）の位置で停止する。
【００５６】
電磁コイル３５に供給される電流値が更に高い場合には、弁体３７を吸引する力がさらに大きくなり、第１スプリング３４と第２スプリング３６の付勢力の和に抗し弁体３７は上昇する。すると、図２に示すように、弁体３７がバルブ室６２の内部に形成された第２の開口部６５に当接し、第２の開口部６５を閉塞して停止するまでの第２のリフトをする。なお、図１に示すように弁体３７が、低圧開口部６７に着座した位置から第２の開口部６５に当接するまでのリフト量はＨ２である。弁体３７が第１のリフトから第２のリフトへ移動する量は（Ｈ２−Ｈ１）である。
【００５７】
次に燃料噴射弁１の作動について図１から図３とともに図４を用いて説明する。
【００５８】
図示しないエンジン制御装置（ＥＣＵ）により、エンジン運転条件に応じた電磁コイル３５への駆動電流が生成され、電磁コイル３５に供給される。駆動電流が供給されることによりアーマチャ３２が吸引され弁体３７がリフトする。
【００５９】
弁体３７のリフトがＨ２のときは（図２および図４中のタイミング（Ａ）参照）、バルブ室６２と低圧通路６３とが連通されたままで第２圧力室５１とバルブ室６２間の通路が第２の開口部６５により遮断される。すなわち、図示しないコモンレールからの高圧燃料が供給されている第２圧力室５１は、低圧通路６３とは連通していない状態となる。一方、第１圧力室５０と低圧通路６３はバルブ室６２の第１の開口部６６を介して連通するために第１圧力室５０の燃料圧力（ＰＣ１）が低下し、第１ニードルスプリング１５の設定荷重と第１圧力室５０の燃料圧力から受ける力との合力である噴孔閉塞方向の力が燃料溜り部の燃料圧力によるニードル２３を押し上げる力より小さくなるとニードル２３は開弁し始める。第１圧力室５０の燃料圧力が低下し、ニードル２３は上昇していくが、ニードル２３が（ｈ１リフト）上昇すると第１ピストン２１は第２ピストン２２の下面に当接する。この時、第２圧力室５１の燃料圧力（ＰＣ２）は高いままに保持され、第２圧力室５１の燃料圧力から受ける力が噴孔閉塞方向に働いてニードル２３を押し上げる力よりも大いため、ニードル２３は（ｈ１リフト）以上リフトしない。
【００６０】
また、弁体３７のリフトがＨ１のときは（第３図および図４中のタイミング（Ｂ）参照）、第１の開口部６６、第２の開口部６５、低圧開口部６７の全てが開放されて、第１圧力室５０および第２圧力室５１は、低圧通路６３と連通するために、第１圧力室５０および第２圧力室５１の燃料圧力は低下する。このため噴孔閉塞方向にはたらく力がニードル２３を押し上げる力より小さくなりニードル２３は（ｈ１リフト）以上リフトして（ｈ２リフト）まで上昇する。このときニードル２３の肩部２３ａがハウジング１１の下端面１１ａに係止され、ニードル２３はこれ以上リフトしない。
【００６１】
図４中のタイミング（Ｃ）に示すように噴射期間中に弁体３７のリフト量をＨ２からＨ１に変化させることにより、ニードル２３のリフトをｈ１からｈ２に段階状に変化させることも可能である。
【００６２】
所定の時間が過ぎて電磁コイル３５への駆動電流の供給が停止され弁体３７が低圧開口部６７を閉弁すると、低圧通路６３とバルブ室６２が遮断されるため第１圧力室５０および第２圧力室５１の燃料圧力が上昇して第１ピストン２１、第２ピストン２２をニードル２３閉弁方向に押し下げる力が上昇し、ニードル２３を閉塞する。
【００６３】
このように、一つの弁体よりなる簡潔な構成の制御弁としたことで燃料噴射弁自体の構造を小型化でき、従来に比べて安価な燃料噴射弁となり、かつ第１ピストンおよび第２ピストンを段階的にリフトさせて噴射率を可変可能な燃料噴射弁とすることができる。
【００６４】
また、弁体３７が第２のリフトをして、第１ピストン２１のみがリフトする、すなわち弁部材であるニードル２３がｈ１するときには、高圧回路６０等の高圧燃料が低圧通路６３側へ抜けることなく、ニードル２３のｈ１リフトが達成できる構成となっている。このため、ニードル２３がｈ１リフトしているときにおける、高圧燃料を圧送する燃料ポンプの無駄な仕事が抑制されて燃費向上効果がある。
【００６５】
（変形例）
第１実施例において、ニードル２３を噴孔１１閉塞方向に付勢する手段として第１ニードルスプリング１５を配設した。本変形例では、図５に示すように第１ニードルスプリング１５（図１）に加えて第２ニードルスプリング１７を第２圧力室５１内部に設ける構成とした。
【００６６】
第２ニードルスプリング１７は、第１圧力室５０の燃料圧力が低下して第１ピストン２１がリフトし第２ピストン２２に当接し、第１ピストン２１のリフトによる慣性力が第２ピストン２２を押し上げることのないように第２圧力室５１の燃料圧力に加えて第２ピストン２２を噴孔閉塞方向に付勢させることで、確実に（ｈ１リフト）のみリフトさせる効果がある。よって、安定した噴射量が得られる燃料噴射弁とすることができる。
【００６７】
（第２実施例）
本発明の第２実施例を図６に示す。第１の実施例と実質的に同一構成部分に同一符号を付し説明を省略する。第１の実施例とは、電磁コイル３５をアーマチャ３２の下部に配置した点が異なる。本構成にすることにより、電磁コイル３５に通電したことによるアーマチャ３２に働く吸引力は下降方向に働き、弁体３７は下方にリフトする。電磁コイル３５への駆動電流の供給が停止されているときは、低圧開口部６７を閉鎖して第１圧力室５０、第２圧力室５１の燃料圧力を上昇させてニードル２３を閉弁させ無噴射状態としたいので、低圧開口部６７を上部に配置でき、高圧通路６２と低圧通路６４の配置を変えることができる。上述した構成としたことで、弁体３７とボディ３１間の隙間部３１ａからの燃料リーク量を低減できる。
【００６８】
（第３実施例）
本発明の第３実施例を図７に示す。第１の実施例と実質的に同一構成部分に同一符号を付し説明を省略する。第１の実施例とは、弁体３７の駆動力として電磁コイル３５の代わりに圧電素子を用いた点が異なる。圧電素子１０１は、ハウジング１１に嵌挿され、図示しない制御用コンピュータの指示に従い、駆動電源から電荷を供給されることで、圧電素子１０１はニードル２３軸方向に長さを変化させる。
【００６９】
圧電素子１０１の上端部はハウジング１１に位置規定されているので、全長を変化させて第１油圧ピストン１０２方向に力が伝わる。第１油圧ピストン１０２は、ばね１０４により上方に付勢され、圧電素子１０１の動きに追随するよう設定されている。第１油圧ピストン１０２は、ＡＨ１（第１油圧ピストン１０２の）断面積で下の油圧室１０３にある燃料を介して、断面積ＡＨ２の第２油圧ピストン１０５を押すことで、第２油圧ピストン１０５が面積比の逆数（ＡＨ１／ＡＨ２）のリフト量を圧電素子１０１によって駆動されることになる。
【００７０】
油圧室１０３は、ハウジング１１、油圧ピストン１０２、１０５によって形成されている。第２油圧ピストン１０５はストッパ１０８によって上方の動きを規定され、ばね１０６により上方に付勢されている。ばね１０６は、ハウジング１１の内径部１０７に構成され、内径部１０７は低圧通路６３を介して図示しない燃料タンクへ連通している。
【００７１】
第２油圧ピストン１０５は、その小径部１０９が適当な微小距離をおいて、弁体３７に当接するように構成されている。内径部１０７は、弁体３７が下方に開弁して低圧開口部６７を開放した時は、連絡通路６４を介して第１圧力室５０に連通するとともに連絡通路６１を介して第２圧力室５１と連通している。また第２圧力室５１は図示しないコモンレールと連通している高圧通路６０と連通している。
【００７２】
この構成によれば、圧電素子１０１へかける電荷を変えて弁体３７のリフト量を制御することにより、第１の実施例と同様な作動をすることが可能となる。
【００７３】
ニードル２３を（ｈ１リフト）までリフトさせるときには、大変位を与えるように圧電素子１０１を駆動する。圧電素子１０１が伸びるに従い、ばね１０４に抗して第１油圧ピストン１０２が駆動される。ピストン１０２の変位に従い油圧室１０３内の燃料を加圧して燃料圧力を上昇させる。高圧燃料は第２油圧ピストン１０５を下方に、ばね１０６に抗して駆動する。そして、第２油圧ピストン１０５の小径部１０９は弁体３７に当接し、弁体３７は下方に移動しプレート３９に当接する。この時、弁体３７により内径部１０７と連絡通路６１は遮断されている。弁体３７が下方に移動すると第１圧力室５０は連絡通路６４、内径部１０７を介して低圧通路６３と連通するため第１圧力室圧力は低下し、噴孔を閉塞方向に働く力が小さくなるためにニードル２３は開弁する。ニードル２３の上昇に従い第１ピストン２１が第２ピストン２２に当接するが、第２圧力室５１の燃料圧力が高圧であるためニードル２３のリフトの上昇は停止する。
【００７４】
小変位を与えるように圧電素子１０１を駆動すると、第２油圧ピストン１０５の小径部１０９は弁体３７に当接し、プレート３４へは当接しない位置に圧電素子１０１の変位量を調整する。第１圧力室５０と第２圧力室５１は連絡通路６４、６２および内径部１０７を介して低圧通路６３と連通するために、第１圧力室５０、第２圧力室５１の燃料圧力が低下する。これにより、第１ピストン２１が第２ピストン２２に当接後も、噴孔閉塞方向に働く力がニードル２３の押し上げ力よりも小さくなるなるため、ニードル２３はチップパッキン１４に当接するまで（リフト量：Ｈ２）リフトする。
【００７５】
また、このように噴射中に圧電素子１０１の変位量を切り換えることにより、ブーツ噴射率のような噴射率を得ることも可能である。
【００７６】
上述した構成の圧電素子１０１による制御弁は、電荷を加えることに対する変位応答性が早く、ニードル２３のリフト応答性の優れる燃料噴射弁とすることができる。
【００７７】
（第４実施例）
本発明の第４実施例を図８に示す。第１の実施例と実質的に同一構成部分に同一符号を付し説明を省略する。第１の実施例とは、高圧燃料を第一圧力室５０と連通させ、第２ピストン２２側でニードル２３の（ｈ１リフト）の移動量を規定した点が異なる。
【００７８】
第４実施例の作動を以下説明する。
【００７９】
弁体３７のリフトがＨ２のとき、弁体３７は第２の開口部６５を閉塞して第１圧力室５０の圧力は低圧通路６３と遮断される。この第１圧力室５０の燃料圧力は、高圧通路６０および連絡通路２０２を経由して第１圧力室に導入されて高圧状態を維持する。一方第２圧力室５１の燃料圧力は、連絡通路２６１、第１の開口部６６および低圧開口部６７の順に経由して低圧通路６３へと連通されて低圧となる。よって、第２ピストン２２の閉弁側への付勢力が小さくなるために第２ピストン２２は上昇し、第２圧力室５１上部に設けた係止部材２０１に当接し（ｈ１リフト）停止する。
【００８０】
一方、第１圧力室５０は高圧が維持されているが第２ピストン２２が上昇することにより体積変化し、第１圧力室５０の燃料圧力は低下する。しかし、第１圧力室５０の圧力は高圧を維持するように連絡通路２０２からの燃料供給量を絞り部２０３により調整することで第１ピストン２１は、隙間ｈ２を維持している。
【００８１】
弁体３７のリフトがＨ１のときは、第１圧力室５０、第２圧力室５１の圧力とも低下するためにニードル２３のリフトはさらに上昇して（ｈ２リフト）する。
【００８２】
このような第４実施例の構成にすることにより、第１リフト量（ｈ１リフト）の調整が簡単となる。
【００８３】
（第５実施例）
本発明の第５実施例を図９に示す。第１の実施例と実質的に同一構成部分に同一符号を付し説明を省略する。第１の実施例と異なるのは、高圧通路６０から第２圧力室５１へ高圧燃料が導入される経路を変更した点である。
【００８４】
第１から第３の実施例中の高圧通路６０から第２圧力室５１への高圧燃料が導入される経路は、連絡通路６８を経由していた。第５実施例では、第１実施例の連絡通路６８に代えて、バルブ室６２と第２圧力室５１を連結する連絡通路６１に高圧通路６０を連結する連絡通路３６８を配置した。尚、連絡通路３６８は、連絡通路６１経路に設けられた絞り部３０１に対してバルブ室側の連絡通路６１と接続させる。
【００８５】
上記した構成により、第１から第３の実施例に対し高圧通路６０から第１圧力室５０への連通する燃料通路中の絞り部が１つ削減できる効果がある。
【００８６】
絞り部が１つ削減できると、弁体３７が閉弁し低圧開口部６７を閉塞した時（弁体３７のリフトが０のとき）、第１圧力室５０への燃料供給がスムーズに行われるために第１圧力室５０の圧力上昇が早くなる。このために噴孔を閉塞方向に働く力が早く大きくなりニードル２３の下降速度が速くできる。つまり、ニードル２３の閉弁応答性が向上する。
【００８７】
（第６実施例）
本発明の第６実施例を図１０に示す。第１の実施例と実質的に同一構成部分に同一符号を付し説明を省略する。本発明の第６実施例は、第５の実施例に示したニードル２３下降速度を向上させる方法とは別の方法でニードル２３下降速度を向上させる。
【００８８】
第１の実施例と異なるのは、高圧通路６０から第２圧力室５１へ高圧燃料が導入される連絡通路４０１を追加した点である。
【００８９】
図１０に示す様に、高圧通路６０と第１圧力室５０の間を、絞り部４０２を介して連絡通路４０１により連通させる。この構成にすると高圧通路６０から第１圧力室５０への燃料通路は、バルブ室６２経由の連絡通路６４に加えて、連絡通路４０１からも高圧燃料が導入できる。
【００９０】
上記した構成により、ニードル２３閉弁時の第１圧力室５０への流入燃料量が増加でき、第１圧力室５０の圧力上昇を早くできる。高圧通路６０と第１圧力室５０間の絞り部４０２の面積は、ニードル２３開弁時に高圧通路６０から第１圧力室５０方向への燃料リーク量が増加しない程度に設定する必要がある。
【００９１】
（変形例）
第６実施例において、バルブ室６２と第２圧力室５１間を連通する連絡通路６１に絞り部３０１を配設している。本変形例では、図１１に示すように低圧通路６３に絞り部４０３を設ける構成とした。
【００９２】
弁体３７が図１１中下方にリフトすると、第２圧力室５１の高圧燃料が連絡通６１路、バルブ室６２、低圧通路６３の順に経由して導入される。
【００９３】
よって、絞り部は本変形例の位置に変更しても、第２圧力室５１から低圧通路６３の経路にあり、第２圧力室５１の高圧から低圧に変化する燃料圧力の移行速度を調節している。
【００９４】
一方、本変形例により高圧通路６０から第１圧力室５０への燃料通路である連絡通路６１に第６実施例で示した絞り部３０１が無くなり、ニードル２３閉弁時の第１圧力室５０への流入燃料量が増加でき、第１圧力室５０の圧力上昇を早くできるのでニードル２３下降速度を向上させる効果がある。
【００９５】
（第７実施例）
本発明の第７実施例を図１２に示す。第１の実施例と実質的に同一構成部分に同一符号を付し説明を省略する。本発明の第７実施例は、第５および第６の実施例に示したニードル２３下降速度を向上させる方法とは別の方法でニードル２３下降速度を向上させる。
【００９６】
第１の実施例と構成上異なるのは、高圧通路６０から第２圧力室５１へ高圧燃料が導入される連絡通路５０１を追加した点である。
【００９７】
図１２に示す様に、第２圧力室５１と第１圧力室５０を絞り部５０２を介して連絡通路５０１を第２ピストン内に設けることにより連通させる。この構成にすると高圧通路６０から第１圧力室５０への燃料通路は、バルブ室６２経由の連絡通路６４に加えて、連絡通路６８、第１圧力室５０を経由して連絡通路５０１からも高圧燃料が導入できる。
【００９８】
上記した構成により、ニードル２３閉弁時の第１圧力室５０への流入燃料量が増加でき、第１圧力室５０の圧力上昇を早くできる。高圧通路６０と第１圧力室５０間の絞り部５０２の面積は、ニードル２３開弁時に第２圧力室５１から第１圧力室５０方向への燃料リーク量が増加しない程度に設定する必要がある。
【００９９】
また、上記した第５および第６の実施例と組合わせることにより、よりニードル２３閉弁時のリフト下降速度が向上でき燃料噴射率のシャープカット性能が向上する。
【０１００】
（変形例）
第７実施例において、プレート３９にもうけた連絡通路６４に絞り部５０３を配設した。この絞り部５０３は、例えばプレート３９に細孔を設け、この細孔の径を調整して燃料流量を調整する絞り部である。
【０１０１】
本変形例では、図１３に示すように絞り効果を成す細孔よりなる連絡通路６４を構成するプレート３９のバルブ室６２側に広いテーパ口部６４ａを構成した。このテーパ口部６４ａの広い側の径は縮小することなくバルブ室６２側と接続される。
【０１０２】
高圧通路６０から第１圧力室５０への燃料通路は、第２圧力室５１、バルブ室６２の順に経由して高圧燃料が導入されるので、導入経路が長く第１圧力室５０が高圧化するのに時間がかかる。高圧燃料を導入する側、つまりバルブ室６２側に広いテーパ口部６４ａを構成することで高圧燃料を導き入れ易くなり、第１圧力室５０が早く高圧化する効果がある。
【図面の簡単な説明】
【図１】本発明の第１実施例による燃料噴射弁を示す断面図である。
（Ａ）は、全体断面図である。
（Ｂ）は、【図１】（Ａ）図の９０°回転断面図である。
【図２】図１に示す燃料噴射弁の弁体が第２リフトした状態を示す部分断面図である。
【図３】図１に示す燃料噴射弁の弁体が第１リフトした状態を示す部分断面図である。
【図４】第１実施例の段階リフトを実現するタイムチャートである。
【図５】本発明の第１実施例の変形例による制御弁を示す断面図である。
【図６】本発明の第２実施例を示し電磁コイルの配置を変更した部分断面図である。
【図７】本発明の第３実施例による燃料噴射弁を示す全体断面図である。
【図８】本発明の第４実施例による燃料噴射弁を示す部分断面図である。
【図９】本発明の第５実施例による燃料噴射弁を示す部分断面図である。
【図１０】本発明の第６実施例による燃料噴射弁を示す部分断面図である。
【図１１】本発明の第６実施例の変形例による燃料噴射弁を示す部分断面図である。
【図１２】本発明の第７実施例による燃料噴射弁を示す部分断面図である。
【図１３】本発明の第７実施例の変形例による燃料噴射弁の絞り部を示す部分断面図である。
【符号の説明】
１燃料噴射弁
１１噴孔
１３弁ボディ
１３ａ弁座
１５第１ニードルスプリング（付勢手段）
１７第２ニードルスプリング（付勢手段）
２０制御装置（制御手段）
２１第１ピストン
２２第２ピストン
２３ニードル（弁部材）
２４ロッド
３０制御弁
３２アーマチャ
３３ストッパー
３４第１スプリング（第１のバネ）
３５電磁コイル
３６第２スプリング（第２のバネ）
３２、３３、３４、３５、３６駆動装置
３７弁体
５０第１圧力室
５１第２圧力室
６０高圧通路
６２バルブ室
６３低圧通路
６４ａテーパ口部
６５第２の開口部
６６第１の開口部
６７低圧開口部
１０１圧電素子（ピエゾアクチュエーター）
２０１係止部材
３０１第１の絞り部
４０２第２の絞り部
４０３第３の絞り部
５０２第４の絞り部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve capable of injecting fuel in stages.
[0002]
[Prior art]
Conventionally, in order to achieve both low emissions (NOX, HC, black smoke), high output, and low fuel consumption in a diesel engine, it is necessary to make the injection rate variable according to the operating conditions of the engine. In order to realize this requirement, a two-stage valve opening pressure nozzle having two springs configured to urge the needle is known as a conventional technique.
[0003]
However, in this technique, the fuel pressure pumped from the fuel injection pump varies depending on the engine operating condition, so that it is difficult to realize the injection rate required by the engine under all operating conditions.
[0004]
Therefore, for example, a conventional fuel injection valve disclosed in US Pat. No. 5,694,903 includes a control chamber for applying fuel pressure to the needle in the direction of closing the nozzle hole. This controls injection by the magnitude relationship between the force received in the opening direction by the fuel pressure introduced into the nozzle fuel reservoir and the force received in the injection hole closing direction from the fuel pressure in the control chamber. By changing the opening area of the pilot valve stem that controls the fuel pressure in the control chamber, the control chamber pressure is changed, and the needle is lifted stepwise to obtain the required injection rate.
[0005]
Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 10-54323, fuel injection in which a control valve is disposed at each of an inlet portion and an outlet portion of high-pressure fuel to the control chamber to control the needle lift stepwise. There is a valve. According to this configuration, since the opening / closing control of the entrance and exit to the control room can be controlled independently, stable lift control and the amount of leakage can be reduced.
[0006]
[Problems to be solved by the invention]
However, in the conventional fuel injection valve configuration disclosed in US Pat. No. 5,694,903, the fuel pressure in the control chamber changes depending on the opening area of the stem, the fuel properties, the fuel temperature, etc. It became stable and stable injection rate control was difficult. In addition, a two-way valve is used as the control valve for controlling the control chamber pressure, and the high pressure fuel is constantly leaked through the control chamber and the discharge passage during the injection period. Increased, causing fuel consumption deterioration.
[0007]
In Japanese Patent Laid-Open No. 10-54323, since a plurality of solenoid valves are required, the fuel injection valve becomes large and expensive.
[0008]
In view of the above points, an object of the present invention is a fuel injection capable of controlling the needle lift in a stepwise manner so as to stably obtain the required injection rate in accordance with the entire operating state of the engine with a relatively small structure. To provide a valve.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the fuel injection valve according to claim 1 and claim 2 of the present invention is stepwise by a drive device that electrically drives one valve body in the valve chamber constituting the control valve. By lifting the first opening, the first opening communicating with the first pressure chamber, the second opening communicating with the second pressure chamber, the low pressure opening communicating with the low pressure passage, the first opening or The low pressure opening was opened and closed to change the fuel pressure in the first pressure chamber and / or the second pressure chamber.
[0010]
The fuel injection valve lifts the first piston and the second piston stepwise by changing the pressures of the first pressure chamber and the second pressure chamber by stepwise lifting operation of one valve body. Since the first piston and the second piston cooperate with the valve member, the lift of the valve member can be controlled stepwise.
[0011]
As described above, the control valve having a simple configuration including a single valve body enables the fuel injection valve to be reduced in size, and the injection rate can be varied by lifting the first piston and the second piston in stages. A fuel injection valve.
[0012]
The fuel injection valve according to claim 3 of the present invention controls the fuel pressure in the first pressure chamber and the second pressure chamber by changing the fuel pressure in the first pressure chamber and the second pressure chamber in the following three steps. ing.
[0013]
First, before lifting the valve body in the valve chamber, the valve body closes the low-pressure opening. The high pressure fuel in the high pressure passage is guided to the valve chamber through the second opening of the valve chamber, and then the high pressure fuel is communicated to the first pressure chamber through the first opening. On the other hand, although the high pressure circuit communicated with the second pressure chamber communicates with the valve chamber, the low pressure opening is closed by the valve body. Therefore, the first piston and the second piston are urged in the valve closing direction by the high pressure fuel in the first pressure chamber and the second pressure chamber. The valve member is seated on the valve seat together with the biasing means for biasing the valve member in the nozzle hole closing direction in accordance with the lift amount of the valve member.
[0014]
Next, when the valve body performs the first lift, the valve body opens the low pressure opening, and the high pressure fuel in the first pressure chamber and the second pressure chamber communicates with the low pressure passage through the low pressure opening of the valve chamber. Therefore, the fuel pressure in the first pressure chamber and the second pressure chamber changes from the high pressure state to the low pressure state, and the first piston and the second piston lift in the valve opening direction as follows.
[0015]
When the first piston is lifted, it comes into contact with the second piston, and the second piston is lifted so that both the first piston and the second piston are lifted, so that the lift amount of the first piston and the lift amount of the second piston are The valve member is lifted by the combined amount, the valve member is separated from the valve seat, and fuel is injected from the injection hole.
[0016]
Next, when the valve body is lifted more than the first lift and then the second lift is performed, the first pressure chamber remains in communication with the low pressure passage through the valve chamber, so that the fuel pressure in the first pressure chamber is changed from the high pressure state to the low pressure state. The valve body closes the second opening, and the second pressure chamber blocks communication with the low-pressure passage. Therefore, the fuel pressure in the second pressure chamber is maintained at a high pressure, and the second piston is urged in the valve closing direction. That is, the first piston lifts and contacts the second piston, the valve member lifts by the lift amount of the first piston, the valve member moves away from the valve seat, and fuel is injected from the injection hole.
[0017]
In this way, a simple control valve composed of a single valve body provides an inexpensive fuel injection valve, and the first and second pistons are lifted stepwise to vary the injection rate. It can be a valve.
[0018]
Further, when the valve body performs the second lift and the valve member lifts by the lift amount of the first piston, the high pressure circuit and the low pressure circuit are shut off by closing the second opening. The wasteful work of the fuel pump that pumps the fuel is suppressed, and the fuel consumption is improved.
[0019]
According to a fourth aspect of the present invention, the urging means includes first urging means for urging the valve member in the nozzle hole closing direction regardless of the lift amount of the valve member. The first urging means is configured such that when the first pressure chamber and the second pressure chamber are connected to the low pressure passage and the urging force of the first piston and the second piston in the valve member closing direction is reduced, the valve member The urging force in the valve closing direction is maintained to prevent the valve member from separating from the valve seat.
[0020]
On the other hand, when the valve member is lifted more than the first lift, the second piston is provided so as to bias the valve member in the nozzle hole closing direction. The second piston is biased in the injection hole closing direction so that the inertial force due to the lift of the piston does not push up the second piston. Therefore, it can be set as the fuel injection valve from which the stable injection amount is obtained.
[0021]
In the fuel injection valve according to claim 5 of the present invention, the valve body lifts toward the drive device side and closes the low pressure opening, so that the valve body support portion where the valve body lifts and slides by the drive device is in a low pressure fuel atmosphere. It is in. Therefore, the amount of fuel leakage from the gap required for sliding the valve body support portion can be reduced.
[0022]
According to a sixth aspect of the present invention, in the fuel injection valve according to the sixth aspect of the present invention, the passage that connects the high pressure passage and the second pressure chamber is a first passage in which the high pressure passage is disposed in a passage that connects the second opening and the second pressure chamber. It is configured to be connected to the throttle portion at a position on the valve chamber side.
[0023]
When the first pressure chamber changes the fuel pressure from low pressure to high pressure, the high pressure fuel is supplied through the high pressure passage and the valve chamber, but compared with the case where the first pressure chamber is supplied from the high pressure passage through the second pressure chamber. Thus, there is an effect that one throttle portion between the high pressure passage and the second pressure chamber can be reduced.
[0024]
If the throttle part can be reduced by one, the fuel is smoothly supplied to the first pressure chamber, so that the pressure increase in the first pressure chamber is accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0025]
According to a seventh aspect of the present invention, there is provided a fuel injection valve having a passage connected between the high pressure passage and the first pressure chamber via a second throttle portion for adjusting the fuel flow.
[0026]
With this configuration, the high-pressure fuel can be introduced into the fuel passage from the high-pressure passage to the first pressure chamber not only through the valve chamber but also from the passage connecting the high-pressure passage and the first pressure chamber.
[0027]
With the configuration described above, the amount of fuel flowing into the first pressure chamber when the valve member is closed can be increased, and the pressure increase in the first pressure chamber can be accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0028]
The fuel injection valve according to claim 8 of the present invention is configured to be connected between the first pressure chamber and the second pressure chamber via a fourth throttle portion that adjusts the fuel flow.
[0029]
With this configuration, the high-pressure fuel can be introduced into the fuel passage from the high-pressure passage to the first pressure chamber not only via the valve chamber but also from the passage connecting the first pressure chamber and the second pressure chamber described above.
[0030]
With the configuration described above, the amount of fuel flowing into the first pressure chamber when the valve member is closed can be increased, and the pressure increase in the first pressure chamber can be accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0031]
The fuel injection valve according to claim 9 of the present invention comprises: Valve chamber And second 1 In the passage communicating with the pressure chamber, a wide tapered port portion is formed on the valve chamber side.
[0032]
The wide taper port on the valve chamber side facilitates the introduction of a high-pressure fuel flow when high-pressure fuel is introduced into the first pressure chamber via the valve chamber, and has the effect of increasing the pressure of the first pressure chamber quickly. is there. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the valve member can be increased. That is, the valve closing response of the valve member is improved.
[0033]
In the fuel injection valve according to the tenth aspect of the present invention, the first throttle portion is eliminated, and the third throttle portion is disposed in the low-pressure passage so that the third throttle portion replaces the first throttle portion. Thus, the fuel flow between the high pressure passage and the first pressure chamber is adjusted.
[0034]
When the fuel pressure is changed from the high pressure to the low pressure in the second pressure chamber, even if the third throttling portion is rearranged in the low pressure passage instead of the first throttling portion, the third throttling portion is the first throttling portion. Similarly, the fuel pressure is in the path from the second pressure chamber to the low pressure passage, and the fuel pressure transition speed changing from high pressure to low pressure in the second pressure chamber is adjusted.
[0035]
On the other hand, since the first throttle portion is eliminated in the fuel passage from the high pressure passage to the first pressure chamber, the amount of fuel flowing into the first pressure chamber can be increased when the valve member is closed, and the pressure in the first pressure chamber is increased. As a result, the lowering speed of the valve member can be improved. That is, the valve closing response of the valve member is improved.
[0036]
According to an eleventh aspect of the present invention, the fuel injection valve communicates with the first pressure chamber by lifting one valve body in the valve chamber constituting the control valve stepwise by a drive device that electrically drives the control valve. The fuel pressure in the first pressure chamber and the second pressure chamber is changed by changing the first opening, the second opening communicating with the second pressure chamber, and the low pressure opening communicating with the low pressure passage through the following three steps. Is controlling.
[0037]
First, before lifting the valve body in the valve chamber, the valve body closes the low-pressure opening. The high-pressure fuel in the high-pressure passage is guided into the valve chamber through the second opening of the valve chamber, and then the high-pressure fuel is communicated with the first pressure chamber through the first opening. On the other hand, although the high pressure circuit communicated with the second pressure chamber communicates with the valve chamber, the low pressure opening is closed by the valve body. Therefore, the first piston and the second piston are urged in the valve closing direction by the high pressure fuel in the first pressure chamber and the second pressure chamber. The valve member is seated on the valve seat together with the biasing means for biasing the valve member in the nozzle hole closing direction in accordance with the lift amount of the valve member.
[0038]
Next, when the valve body performs the first lift, the valve body opens the low pressure opening, and the high pressure fuel in the first pressure chamber and the second pressure chamber communicates with the low pressure passage through the low pressure opening of the valve chamber. Therefore, the fuel pressure in the first pressure chamber and the second pressure chamber changes from the high pressure state to the low pressure state, and the first piston and the second piston lift in the valve opening direction as follows.
[0039]
When the second piston is lifted and locked to the locking member, the lift is restricted. When the first piston is lifted, the lift is restricted by contacting the second piston. The valve member is lifted by the sum of the lift amount of the first piston and the lift amount of the second piston, the valve member is separated from the valve seat, and fuel is injected from the injection hole.
[0040]
Next, when the valve body lifts more than the first lift and performs the second lift, since the second pressure chamber remains in communication with the low pressure passage through the valve chamber, the fuel pressure in the second pressure chamber is changed from the high pressure state to the low pressure state. The valve body closes the first opening and the first pressure chamber blocks communication with the low-pressure passage. Here, the first pressure chamber maintains a high pressure state, but the volume changes as the second piston rises, and the fuel pressure in the first pressure chamber decreases. However, the first piston moves by the amount of movement of the second piston by adjusting the supply of high-pressure fuel so that the pressure in the first pressure chamber is maintained at a high level. That is, the second piston is driven to the first piston by the lift amount of the first piston, the valve member is lifted, the valve member is separated from the valve seat, and the fuel is injected from the injection hole.
[0041]
With the above configuration, the valve member lift adjustment (the lift amount of the second piston) is facilitated.
[0042]
The fuel injection valve according to claim 12 of the present invention is such that the electrically driven drive device lifts the valve body by an electromagnetic coil. By using an electromagnetic coil, the electromagnetic coil can be mounted in a limited space, and the physique of the drive device can be made compact.
[0043]
A fuel injection valve according to a thirteenth aspect of the present invention is the fuel injection valve according to any one of the first to tenth aspects, wherein the electrically driven drive device lifts the valve body by a piezo actuator. It was set as the structure to do. The piezo actuator can be a fuel injection valve that has a quick displacement response to the application of electric charge and an excellent lift response of the valve member.
[0044]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of examples showing embodiments of the present invention will be described in detail with reference to the drawings.
[0045]
(First embodiment)
The configuration of the fuel injection valve according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. FIG. 1 is an overall sectional view of a fuel injection valve according to a first embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing a state where the valve body of the fuel injection valve shown in FIG. 1 is lifted second. FIG. 3 is a partial cross-sectional view showing a state where the valve body of the fuel injection valve shown in FIG. 1 is first lifted.
[0046]
As shown in FIG. 1, the structure of the fuel injection valve 1 is basically that a first piston 21 and a second piston 22 are arranged above the first piston 21 in the fuel injection valve housing 10, and further the first piston. A first pressure chamber 50 is formed between the first piston 21 and the second piston 22, and a second pressure chamber 51 is formed on the upper surface of the second piston 22. The fuel pressure in the first pressure chamber 50 and the second pressure chamber 51 is controlled by the electromagnetic valve 30 disposed above the second pressure chamber 51, so that it is provided below the first piston 21 and will be described later. By changing the lift amount of the needle 23 that opens and closes the injection hole 11, the injection rate shape can be freely set.
[0047]
A housing 10 of the fuel injection valve 1 and a valve body 13 provided below the housing 10 are fastened by a retaining nut 12 with a tip packing 14 interposed therebetween. The control device 20 includes a first piston 21, a first pressure chamber 50, a second piston 22, and a second pressure chamber 51 from the injection hole 11 side formed at the lower end of the valve body 13, and the injection device side of the control device 20. Are arranged with a needle 23 and a rod 24 which cooperate with the control device 20. The needle 23 is supported by the valve body 13 so as to be reciprocally movable. Furthermore, a first needle spring 15 that urges the needle 23 in the direction of the nozzle hole 11 via the rod 24 is provided.
[0048]
Further, the housing 10 is formed with a high-pressure passage 60 communicating with a common rail (not shown). The high-pressure passage 60 passes through the housing 10, the tip packing 14, and the valve body 13 and communicates with the fuel reservoir 16 formed in the valve body 13. Further, the high pressure passage 60 is formed so as to communicate with the second pressure chamber 51 via a communication passage 68. As a result, the high-pressure fuel supplied from the common rail (not shown) is supplied to the second pressure chamber 51 and the fuel reservoir 16 in the valve body 13 via the high-pressure passage 60 in the housing 10. Further, as shown in FIG. 2, the first pressure chamber 50 is communicated with a communication passage 61 opened in the second pressure chamber 51 and a communication passage 64 formed in the housing 10 and the like via a valve chamber 62 described later. The fuel is supplied from the second pressure chamber 51.
[0049]
The control valve 30 is accommodated in the valve cover 38 and is screwed between the upper portion of the housing 10 and the valve cover 38. The control valve 30 includes a body 31, an armature 32, a stopper 33, a first spring 34, an electromagnetic coil 35, a second spring 36, a valve body 37, a plate 39, a valve chamber 62, and the like.
[0050]
The valve chamber 62 is formed in the body 31 and accommodates a valve body 37 connected to the armature 32. A second opening 65 connected to the communication passage 61 is opened at the upper end surface of the valve chamber 62 at the connection portion of the armature 32 with the valve body 37. Further, a first opening 66 connected to the communication passage 64 is opened on the side surface of the substantially central portion of the valve chamber 62. Furthermore, a low pressure opening 67 in which the plate 39 is formed opens at the lower end surface of the valve chamber 62.
[0051]
The low pressure opening 67 is connected to the low pressure passage 63. The low-pressure passage 63 is formed in the housing 10 and the like, and communicates with a fuel tank (not shown) so that the fuel in the valve chamber 62 is discharged to the fuel tank.
[0052]
The valve body 37 can be seated on the low-pressure opening 67 via the armature 32 by the urging force of the first spring 34. Further, the valve element 37 moves upward together with the armature 32 by the suction of the electromagnetic coil 35 and can be seated in the second opening 65.
[0053]
In FIG. 1, the valve element 37 is seated in the low pressure opening 67 without energizing the electromagnetic coil 35, the needle 23 is attached to the fuel pressure of the first pressure chamber 50, the second pressure chamber 51, and the first needle spring 15. A state in which the valve is biased in the valve closing direction by the force and is seated on the valve seat 13A is shown. In addition, 23a shows the shoulder part of the needle 23, 11a shows the lower end surface of the housing 11. FIG.
[0054]
Next, the armature 32 located above the valve body 37 is attracted upward against the biasing force of the first spring 34 by the excitation suction force generated by energizing the coil 35, and the valve body 37 is Lift. This state is shown in FIG.
[0055]
As shown in FIG. 3, the valve body is lifted upward and sucked to the lower end surface of the stopper 33. At this time, since the urging force of the second spring 36 is applied to the valve body 37, the sum of the attraction force from the electromagnetic coil 35 and the urging forces of the first spring 34 and the second spring 36 balances the valve body 37 with the lift H1. Stop at the position (see FIG. 1).
[0056]
When the current value supplied to the electromagnetic coil 35 is higher, the force for attracting the valve element 37 is further increased, and the valve element 37 is raised against the sum of the urging forces of the first spring 34 and the second spring 36. To do. Then, as shown in FIG. 2, the valve body 37 comes into contact with the second opening 65 formed inside the valve chamber 62, and the second lift until the second opening 65 is closed and stopped. do. As shown in FIG. 1, the lift amount from the position where the valve body 37 is seated on the low-pressure opening 67 to the second opening 65 is H2. The amount by which the valve body 37 moves from the first lift to the second lift is (H2-H1).
[0057]
Next, the operation of the fuel injection valve 1 will be described with reference to FIGS. 1 to 3 and FIG.
[0058]
A drive current to the electromagnetic coil 35 corresponding to engine operating conditions is generated by an engine control unit (ECU) (not shown) and supplied to the electromagnetic coil 35. When the drive current is supplied, the armature 32 is sucked and the valve element 37 is lifted.
[0059]
When the lift of the valve body 37 is H2 (see timing (A) in FIGS. 2 and 4), the passage between the second pressure chamber 51 and the valve chamber 62 while the valve chamber 62 and the low-pressure passage 63 remain in communication with each other. Is blocked by the second opening 65. That is, the second pressure chamber 51 to which high pressure fuel from a common rail (not shown) is supplied is not in communication with the low pressure passage 63. On the other hand, since the first pressure chamber 50 and the low pressure passage 63 communicate with each other through the first opening 66 of the valve chamber 62, the fuel pressure (PC1) in the first pressure chamber 50 decreases, and the first needle spring 15 When the force in the nozzle hole closing direction, which is the resultant force of the set load and the force received from the fuel pressure in the first pressure chamber 50, becomes smaller than the force pushing up the needle 23 due to the fuel pressure in the fuel reservoir, the needle 23 begins to open. The fuel pressure in the first pressure chamber 50 decreases and the needle 23 rises. However, when the needle 23 rises (h1 lift), the first piston 21 comes into contact with the lower surface of the second piston 22. At this time, the fuel pressure (PC2) in the second pressure chamber 51 is kept high, and the force received from the fuel pressure in the second pressure chamber 51 is larger than the force that works in the nozzle hole closing direction and pushes up the needle 23. The needle 23 does not lift (h1 lift) or more.
[0060]
When the lift of the valve element 37 is H1 (see timing (B) in FIGS. 3 and 4), all of the first opening 66, the second opening 65, and the low pressure opening 67 are opened. Thus, since the first pressure chamber 50 and the second pressure chamber 51 communicate with the low pressure passage 63, the fuel pressure in the first pressure chamber 50 and the second pressure chamber 51 decreases. Therefore, the force acting in the nozzle hole closing direction is smaller than the force pushing up the needle 23, and the needle 23 is lifted (h1 lift) or more and raised to (h2 lift). At this time, the shoulder 23a of the needle 23 is locked to the lower end surface 11a of the housing 11, and the needle 23 does not lift any more.
[0061]
It is also possible to change the lift of the needle 23 stepwise from h1 to h2 by changing the lift amount of the valve element 37 from H2 to H1 during the injection period as shown in the timing (C) in FIG. is there.
[0062]
When the supply of drive current to the electromagnetic coil 35 is stopped after a predetermined time and the valve element 37 closes the low pressure opening 67, the low pressure passage 63 and the valve chamber 62 are shut off, so the first pressure chamber 50 and the first pressure chamber 50 The fuel pressure in the two pressure chambers 51 rises, and the force that pushes down the first piston 21 and the second piston 22 in the needle 23 closing direction rises, closing the needle 23.
[0063]
As described above, since the control valve having a simple configuration including one valve body is used, the structure of the fuel injection valve itself can be reduced in size, and the fuel injection valve can be made cheaper than the conventional one, and the first piston and the second piston. Can be lifted stepwise to provide a fuel injection valve with variable injection rate.
[0064]
Further, when the valve body 37 performs the second lift and only the first piston 21 lifts, that is, when the needle 23 that is the valve member is h1, high-pressure fuel such as the high-pressure circuit 60 is released to the low-pressure passage 63 side. The h1 lift of the needle 23 can be achieved. For this reason, useless work of the fuel pump that pumps high-pressure fuel when the needle 23 is lifted by h1 is suppressed, and there is an effect of improving fuel consumption.
[0065]
(Modification)
In the first embodiment, the first needle spring 15 is provided as a means for urging the needle 23 in the closing direction of the nozzle hole 11. In this modification, as shown in FIG. 5, the second needle spring 17 is provided inside the second pressure chamber 51 in addition to the first needle spring 15 (FIG. 1).
[0066]
In the second needle spring 17, the fuel pressure in the first pressure chamber 50 decreases, the first piston 21 lifts and comes into contact with the second piston 22, and the inertia force generated by the lift of the first piston 21 pushes up the second piston 22. In order to prevent this, in addition to the fuel pressure in the second pressure chamber 51, the second piston 22 is urged in the injection hole closing direction, so that only (h1 lift) is lifted reliably. Therefore, it can be set as the fuel injection valve from which the stable injection amount is obtained.
[0067]
(Second embodiment)
A second embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that the electromagnetic coil 35 is disposed below the armature 32. With this configuration, the attractive force acting on the armature 32 due to the energization of the electromagnetic coil 35 acts in the downward direction, and the valve element 37 is lifted downward. When the supply of the drive current to the electromagnetic coil 35 is stopped, the low pressure opening 67 is closed to increase the fuel pressure in the first pressure chamber 50 and the second pressure chamber 51, and the needle 23 is not closed. Since the injection state is desired, the low pressure opening 67 can be disposed at the upper portion, and the arrangement of the high pressure passage 62 and the low pressure passage 64 can be changed. With the above-described configuration, the amount of fuel leakage from the gap 31a between the valve body 37 and the body 31 can be reduced.
[0068]
(Third embodiment)
A third embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that a piezoelectric element is used in place of the electromagnetic coil 35 as the driving force of the valve element 37. The piezoelectric element 101 is inserted into the housing 11 and supplied with electric charges from a driving power source according to an instruction of a control computer (not shown), whereby the piezoelectric element 101 changes its length in the axial direction of the needle 23.
[0069]
Since the position of the upper end portion of the piezoelectric element 101 is regulated by the housing 11, the force is transmitted in the direction of the first hydraulic piston 102 by changing the overall length. The first hydraulic piston 102 is biased upward by a spring 104 and is set to follow the movement of the piezoelectric element 101. The first hydraulic piston 102 pushes the second hydraulic piston 105 having the cross-sectional area AH2 through the fuel in the lower hydraulic chamber 103 with the cross-sectional area AH1 (of the first hydraulic piston 102), whereby the second hydraulic piston 105 Is driven by the piezoelectric element 101 with a lift amount that is the reciprocal of the area ratio (AH1 / AH2).
[0070]
The hydraulic chamber 103 is formed by a housing 11 and hydraulic pistons 102 and 105. The second hydraulic piston 105 is regulated to move upward by a stopper 108 and is urged upward by a spring 106. The spring 106 is formed in the inner diameter portion 107 of the housing 11, and the inner diameter portion 107 communicates with a fuel tank (not shown) via the low pressure passage 63.
[0071]
The second hydraulic piston 105 is configured such that the small diameter portion 109 abuts on the valve body 37 at an appropriate minute distance. The inner diameter portion 107 communicates with the first pressure chamber 50 via the communication passage 64 and the second pressure chamber via the communication passage 61 when the valve element 37 opens downward to open the low pressure opening 67. 51 communicates. The second pressure chamber 51 communicates with a high-pressure passage 60 that communicates with a common rail (not shown).
[0072]
According to this configuration, it is possible to perform the same operation as in the first embodiment by changing the charge applied to the piezoelectric element 101 and controlling the lift amount of the valve element 37.
[0073]
When the needle 23 is lifted to (h1 lift), the piezoelectric element 101 is driven so as to give a large displacement. As the piezoelectric element 101 extends, the first hydraulic piston 102 is driven against the spring 104. According to the displacement of the piston 102, the fuel in the hydraulic chamber 103 is pressurized to increase the fuel pressure. The high pressure fuel drives the second hydraulic piston 105 downward against the spring 106. The small diameter portion 109 of the second hydraulic piston 105 abuts on the valve element 37, and the valve element 37 moves downward and abuts on the plate 39. At this time, the inner diameter portion 107 and the communication passage 61 are blocked by the valve body 37. When the valve body 37 moves downward, the first pressure chamber 50 communicates with the low-pressure passage 63 via the communication passage 64 and the inner diameter portion 107, so the first pressure chamber pressure decreases, and the force acting on the nozzle hole in the closing direction is small. Therefore, the needle 23 is opened. The first piston 21 comes into contact with the second piston 22 as the needle 23 is raised, but the lift of the needle 23 stops because the fuel pressure in the second pressure chamber 51 is high.
[0074]
When the piezoelectric element 101 is driven so as to give a small displacement, the small diameter portion 109 of the second hydraulic piston 105 contacts the valve element 37 and adjusts the displacement amount of the piezoelectric element 101 to a position where it does not contact the plate 34. Since the first pressure chamber 50 and the second pressure chamber 51 communicate with the low pressure passage 63 via the communication passages 64 and 62 and the inner diameter portion 107, the fuel pressure in the first pressure chamber 50 and the second pressure chamber 51 decreases. . Thereby, even after the first piston 21 abuts on the second piston 22, the force acting in the nozzle hole closing direction becomes smaller than the pushing force of the needle 23, so that the needle 23 abuts on the tip packing 14 (lift Amount: H2) Lift.
[0075]
Moreover, it is also possible to obtain an injection rate such as the boot injection rate by switching the displacement amount of the piezoelectric element 101 during the injection.
[0076]
The control valve by the piezoelectric element 101 having the above-described configuration can be a fuel injection valve that has a quick displacement response to applying an electric charge and an excellent lift response of the needle 23.
[0077]
(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. This embodiment differs from the first embodiment in that high-pressure fuel is communicated with the first pressure chamber 50 and the amount of movement of the needle 23 (h1 lift) is defined on the second piston 22 side.
[0078]
The operation of the fourth embodiment will be described below.
[0079]
When the lift of the valve body 37 is H2, the valve body 37 closes the second opening 65, and the pressure in the first pressure chamber 50 is blocked from the low pressure passage 63. The fuel pressure in the first pressure chamber 50 is introduced into the first pressure chamber via the high pressure passage 60 and the communication passage 202 to maintain a high pressure state. On the other hand, the fuel pressure in the second pressure chamber 51 is communicated with the low pressure passage 63 through the communication passage 261, the first opening 66, and the low pressure opening 67 in this order, and becomes low pressure. Therefore, since the urging force of the second piston 22 toward the valve closing side becomes small, the second piston 22 rises and comes into contact with the locking member 201 provided on the second pressure chamber 51 (h1 lift) and stops.
[0080]
On the other hand, although the high pressure is maintained in the first pressure chamber 50, the volume of the first pressure chamber 50 changes as the second piston 22 rises, and the fuel pressure in the first pressure chamber 50 decreases. However, the first piston 21 maintains the gap h <b> 2 by adjusting the fuel supply amount from the communication passage 202 by the throttle 203 so that the pressure in the first pressure chamber 50 is maintained at a high pressure.
[0081]
When the lift of the valve body 37 is H1, since the pressures of the first pressure chamber 50 and the second pressure chamber 51 are both reduced, the lift of the needle 23 is further increased (h2 lift).
[0082]
By adopting such a configuration of the fourth embodiment, the adjustment of the first lift amount (h1 lift) is simplified.
[0083]
(5th Example)
A fifth embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that the route through which the high pressure fuel is introduced from the high pressure passage 60 to the second pressure chamber 51 is changed.
[0084]
The path through which the high-pressure fuel is introduced from the high-pressure passage 60 to the second pressure chamber 51 in the first to third embodiments is via the communication passage 68. In the fifth embodiment, instead of the communication passage 68 of the first embodiment, a communication passage 368 for connecting the high pressure passage 60 to the communication passage 61 for connecting the valve chamber 62 and the second pressure chamber 51 is disposed. The communication passage 368 is connected to the communication passage 61 on the valve chamber side with respect to the throttle portion 301 provided in the communication passage 61.
[0085]
With the configuration described above, there is an effect that the throttle portion in the fuel passage communicating from the high pressure passage 60 to the first pressure chamber 50 can be reduced by one as compared with the first to third embodiments.
[0086]
If the throttle portion can be reduced by one, when the valve body 37 is closed and the low pressure opening 67 is closed (when the lift of the valve body 37 is 0), the fuel supply to the first pressure chamber 50 is smoothly performed. Therefore, the pressure increase in the first pressure chamber 50 is accelerated. For this reason, the force acting on the nozzle hole in the closing direction increases quickly, and the descending speed of the needle 23 can be increased. That is, the valve closing response of the needle 23 is improved.
[0087]
(Sixth embodiment)
A sixth embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the sixth embodiment of the present invention, the needle 23 descending speed is improved by a method different from the method of improving the needle 23 descending speed shown in the fifth embodiment.
[0088]
The difference from the first embodiment is that a communication passage 401 through which high-pressure fuel is introduced from the high-pressure passage 60 to the second pressure chamber 51 is added.
[0089]
As shown in FIG. 10, the high-pressure passage 60 and the first pressure chamber 50 are communicated with each other via the throttle portion 402 through the communication passage 401. With this configuration, the fuel passage from the high pressure passage 60 to the first pressure chamber 50 can introduce high pressure fuel from the communication passage 401 in addition to the communication passage 64 via the valve chamber 62.
[0090]
With the configuration described above, the amount of fuel flowing into the first pressure chamber 50 when the needle 23 is closed can be increased, and the pressure increase in the first pressure chamber 50 can be accelerated. The area of the throttle portion 402 between the high pressure passage 60 and the first pressure chamber 50 needs to be set to such an extent that the amount of fuel leakage from the high pressure passage 60 toward the first pressure chamber 50 does not increase when the needle 23 is opened.
[0091]
(Modification)
In the sixth embodiment, the throttle portion 301 is disposed in the communication passage 61 that communicates between the valve chamber 62 and the second pressure chamber 51. In the present modification, a throttle portion 403 is provided in the low pressure passage 63 as shown in FIG.
[0092]
When the valve body 37 is lifted downward in FIG. 11, the high-pressure fuel in the second pressure chamber 51 is introduced through the communication passage 61, the valve chamber 62, and the low-pressure passage 63 in this order.
[0093]
Therefore, even if the throttle portion is changed to the position of the present modification, it is in the path from the second pressure chamber 51 to the low pressure passage 63, and adjusts the fuel pressure transition speed that changes from the high pressure to the low pressure in the second pressure chamber 51. ing.
[0094]
On the other hand, according to this modification, the communication portion 61 that is a fuel passage from the high pressure passage 60 to the first pressure chamber 50 does not have the throttle portion 301 shown in the sixth embodiment, and the first pressure chamber 50 when the needle 23 is closed. The amount of inflow fuel can be increased, and the pressure rise in the first pressure chamber 50 can be accelerated, so that the needle 23 descending speed is improved.
[0095]
(Seventh embodiment)
A seventh embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The seventh embodiment of the present invention improves the needle 23 lowering speed by a method different from the method of improving the needle 23 lowering speed shown in the fifth and sixth embodiments.
[0096]
The difference from the first embodiment is that a communication passage 501 through which high-pressure fuel is introduced from the high-pressure passage 60 to the second pressure chamber 51 is added.
[0097]
As shown in FIG. 12, the second pressure chamber 51 and the first pressure chamber 50 are communicated with each other by providing a communication passage 501 in the second piston through the throttle portion 502. With this configuration, the fuel passage from the high pressure passage 60 to the first pressure chamber 50 has a high pressure from the communication passage 501 via the communication passage 68 and the first pressure chamber 50 in addition to the communication passage 64 via the valve chamber 62. Fuel can be introduced.
[0098]
With the configuration described above, the amount of fuel flowing into the first pressure chamber 50 when the needle 23 is closed can be increased, and the pressure increase in the first pressure chamber 50 can be accelerated. The area of the throttle portion 502 between the high pressure passage 60 and the first pressure chamber 50 needs to be set to such an extent that the amount of fuel leakage from the second pressure chamber 51 toward the first pressure chamber 50 does not increase when the needle 23 is opened. .
[0099]
Further, by combining with the fifth and sixth embodiments described above, the lift lowering speed when the needle 23 is closed can be further improved, and the sharp cut performance of the fuel injection rate is improved.
[0100]
(Modification)
In the seventh embodiment, the throttle portion 503 is disposed in the communication passage 64 provided in the plate 39. The throttle unit 503 is a throttle unit that adjusts the fuel flow rate by, for example, providing a fine hole in the plate 39 and adjusting the diameter of the fine hole.
[0101]
In this modification, as shown in FIG. 13, a wide taper port portion 64a is formed on the valve chamber 62 side of the plate 39 constituting the communication passage 64 formed of the fine pores that achieve the throttling effect. The diameter on the wide side of the tapered port portion 64a is connected to the valve chamber 62 side without being reduced.
[0102]
In the fuel passage from the high-pressure passage 60 to the first pressure chamber 50, high-pressure fuel is introduced through the second pressure chamber 51 and the valve chamber 62 in this order, so that the introduction passage is long and the first pressure chamber 50 is increased in pressure. It takes time. By forming the wide tapered port portion 64a on the side where the high-pressure fuel is introduced, that is, on the valve chamber 62 side, the high-pressure fuel can be easily introduced, and the first pressure chamber 50 can be increased in pressure quickly.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a fuel injection valve according to a first embodiment of the present invention.
(A) is a whole sectional view.
FIG. 1 (B) is a 90 ° rotation cross-sectional view of FIG. 1 (A).
FIG. 2 is a partial cross-sectional view showing a state where a valve body of the fuel injection valve shown in FIG. 1 is second lifted.
FIG. 3 is a partial cross-sectional view showing a state where the valve body of the fuel injection valve shown in FIG. 1 is first lifted.
FIG. 4 is a time chart for realizing the stage lift of the first embodiment.
FIG. 5 is a cross-sectional view showing a control valve according to a modification of the first embodiment of the present invention.
FIG. 6 is a partial cross-sectional view showing a second embodiment of the present invention in which the arrangement of electromagnetic coils is changed.
FIG. 7 is an overall sectional view showing a fuel injection valve according to a third embodiment of the present invention.
FIG. 8 is a partial sectional view showing a fuel injection valve according to a fourth embodiment of the present invention.
FIG. 9 is a partial sectional view showing a fuel injection valve according to a fifth embodiment of the present invention.
FIG. 10 is a partial sectional view showing a fuel injection valve according to a sixth embodiment of the present invention.
FIG. 11 is a partial sectional view showing a fuel injection valve according to a modification of the sixth embodiment of the present invention.
FIG. 12 is a partial sectional view showing a fuel injection valve according to a seventh embodiment of the present invention.
FIG. 13 is a partial sectional view showing a throttle portion of a fuel injection valve according to a modification of the seventh embodiment of the present invention.
[Explanation of symbols]
1 Fuel injection valve
11 hole
13 Valve body
13a Valve seat
15 First needle spring (biasing means)
17 Second needle spring (biasing means)
20 Control device (control means)
21 First piston
22 Second piston
23 Needle (Valve member)
24 Rod
30 Control valve
32 Armature
33 Stopper
34 First spring (first spring)
35 Electromagnetic coil
36 Second spring (second spring)
32, 33, 34, 35, 36 Driving device
37 Disc
50 First pressure chamber
51 Second pressure chamber
60 High pressure passage
62 Valve chamber
63 Low pressure passage
64a taper mouth
65 second opening
66 First opening
67 Low pressure opening
101 Piezoelectric element (piezo actuator)
201 Locking member
301 first aperture
402 Second aperture
403 Third aperture
502 Fourth aperture

Claims

A valve member for opening and closing the nozzle hole;
A valve body having a valve seat on the fuel upstream side of the nozzle hole, wherein the valve member is seated on the valve seat to close the nozzle hole, and the valve member is separated from the valve seat. A valve body for opening and closing the nozzle hole;
Control means for controlling the injection rate of fuel to be injected by lifting the valve member stepwise;
A control valve for switching a communication state between the control means and a high-pressure passage into which high-pressure fuel is introduced, and a communication state between the control means and a low-pressure passage through which the high-pressure fuel is discharged;
Biasing means for biasing the valve member in the nozzle hole closing direction;
The control means includes a first piston and a second piston that cooperate in the axial direction with the valve member, and a first pressure that changes the fuel pressure to lift the first piston and the second piston in the valve opening direction, respectively. A chamber and a second pressure chamber,
The control valve includes a valve chamber including one valve body therein, and an electric drive device that lifts and drives the valve body in stages.
The valve chamber includes a first opening communicating with the first pressure chamber, a second opening communicating with the high pressure passage and the second pressure chamber, and a low pressure opening communicating with the low pressure passage. Provided,
The valve body is lifted stepwise to switch the communication state between the first opening, the second opening, and the low pressure opening, and the fuel pressure in the first pressure chamber and the second pressure chamber is changed. A fuel injection valve characterized by being changed.

The first pressure chamber is provided between the first piston and the second piston, and changes the fuel pressure to lift the first piston in the valve opening direction, and the second pressure chamber is the second pressure chamber. An upper portion of the piston is provided to change the fuel pressure to lift the second piston in the valve opening direction, and the first piston and the second piston are brought into contact with the second piston when the first piston is lifted. In addition, the first piston and the second piston are both lifted by lifting the second piston, and
The fuel injection valve according to claim 1, wherein the high-pressure passage communicates with the second pressure chamber.

Before the valve body is lifted by the drive device, the valve body closes the low-pressure opening,
When the valve body performs a first lift by the driving device, the valve body opens the low pressure opening, and the first pressure chamber and the second pressure chamber communicate with the low pressure passage through the valve chamber,
When the valve body is lifted more than the first lift by the driving device to make the second lift, the first pressure chamber remains in communication with the low pressure passage through the valve chamber, and the valve body opens to the second opening. 3. The fuel injection valve according to claim 1, wherein the second pressure chamber blocks communication and blocks communication with the low-pressure passage. 4.

The biasing means includes a first biasing means for biasing the valve member in the nozzle hole closing direction regardless of a lift amount of the valve member, and a nozzle hole closing direction when the valve member is lifted more than the first lift. The fuel injection valve according to any one of claims 1 to 3, further comprising: a second urging unit that urges the valve member.

The fuel injection valve according to any one of claims 1 to 4, wherein the valve body lifts toward the driving device and closes the low-pressure opening.

A first throttle for adjusting fuel flow is disposed in a passage communicating the second opening and the second pressure chamber;
The passage that communicates the high pressure passage and the second pressure chamber is configured such that the high pressure passage is disposed in a passage that communicates the second opening and the second pressure chamber. The fuel injection valve according to any one of claims 1 to 5, wherein the fuel injection valve is configured by connecting at a position on a valve chamber side.

7. The fuel injection valve according to claim 1, wherein the fuel injection valve is connected between the high-pressure passage and the first pressure chamber via a second throttle portion that adjusts a fuel flow.

8. The fuel injection valve according to claim 1, wherein a connection is made between the first pressure chamber and the second pressure chamber via a fourth throttle portion that adjusts a fuel flow. 9. .

The fuel injection valve according to any one of claims 1 to 8, wherein a wide tapered port portion is formed on the valve chamber side in a passage communicating the valve chamber and the first pressure chamber.

10. The fuel flow between the high pressure passage and the first pressure chamber is adjusted by disposing a third throttle portion in the low pressure passage. 10. The fuel injection valve according to any one of the above.

A valve member for opening and closing the nozzle hole;
A valve body having a valve seat on the fuel upstream side of the nozzle hole, wherein the valve member is seated on the valve seat to close the nozzle hole, and the valve member is separated from the valve seat. A valve body for opening and closing the nozzle hole;
Control means for controlling the injection rate of fuel to be injected by lifting the valve member stepwise;
A control valve for switching a communication state between the control means and a high-pressure passage into which high-pressure fuel is introduced, and a communication state between the control means and a low-pressure passage through which the high-pressure fuel is discharged;
The control means includes a first piston and a second piston that cooperate in the axial direction with the valve member, and an urging means that urges the valve member in a nozzle hole closing direction in accordance with a lift amount of the valve member. ,
A first pressure chamber provided between the first piston and the second piston, wherein the fuel pressure is changed to lift the first piston in a valve opening direction; and an upper portion of the second piston. A second pressure chamber for changing and lifting the second piston in the valve opening direction;
A locking member provided at an upper portion of the second pressure chamber and restricting a lift of the valve member;
The first piston and the second piston are arranged to contact the locking member when the second piston is lifted, and to contact the second piston when the first piston is lifted,
The high pressure passage communicates with the second pressure chamber;
The control valve includes a valve chamber having a single valve body therein, and an electric drive device that lifts the valve body in stages.
The valve chamber includes a first opening communicating with the first pressure chamber, a second opening communicating with the second pressure chamber, and a low pressure opening communicating with the low pressure passage,
Before the valve body is lifted by the driving device, the valve body closes the low-pressure opening, and when the valve body performs the first lift by the driving device, the valve body opens the low-pressure opening. Then, the first pressure chamber and the second pressure chamber communicate with the low pressure passage through the valve chamber, and when the valve body lifts more than the first lift by the driving device and performs the second lift, The two pressure chambers remain in communication with the low pressure passage through the valve chamber, the valve body closes the first opening, and the first pressure chamber blocks communication with the low pressure passage. Fuel injection valve.

The fuel injection valve according to any one of claims 1 to 11, wherein the electrically driven driving device lifts the valve body by an electromagnetic coil.

The fuel injection valve according to any one of claims 1 to 12, wherein the electrically driven drive device lifts the valve body by a piezo actuator.