JP2004270560A - Fuel injection device - Google Patents

Fuel injection device Download PDF

Info

Publication number
JP2004270560A
JP2004270560A JP2003062833A JP2003062833A JP2004270560A JP 2004270560 A JP2004270560 A JP 2004270560A JP 2003062833 A JP2003062833 A JP 2003062833A JP 2003062833 A JP2003062833 A JP 2003062833A JP 2004270560 A JP2004270560 A JP 2004270560A
Authority
JP
Japan
Prior art keywords
fuel
pressure
stage
pump
fuel injection
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2003062833A
Other languages
Japanese (ja)
Inventor
Satoshi Tsusaka
智 津坂
Hiromasa Ono
博正 大野
Shinya Yamaguchi
真也 山口
Masayoshi Tanuma
正義 田沼
Takesuke Takigawa
武相 瀧川
Hayato Majima
隼人 間嶋
Takashi Nunokawa
剛史 布川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nikki Co Ltd
Original Assignee
Nikki Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nikki Co Ltd filed Critical Nikki Co Ltd
Priority to JP2003062833A priority Critical patent/JP2004270560A/en
Publication of JP2004270560A publication Critical patent/JP2004270560A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

Landscapes

  • Fuel-Injection Apparatus (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To inject volatile fuel such as LPG in an always stable liquid condition and reduce electric power consumption of a fuel pump. <P>SOLUTION: Two fuel pumps 7, 8 are provided in series in a supply conduit 2 from a fuel tank 1 to a fuel injection valve 4 and a return conduit 9 of surplus fuel is connected to an inlet side of the second stage fuel pump 8. Liquid fuel F pressurized by the second stage fuel pump 8 during normal operation is sent to the fuel injection valve 4 and surplus fuel is circulated and injection fuel quantity is filled up through the first stage fuel pump 7. The first stage fuel pump 7 is temporally operated at high delivery pressure to increase fuel injection pressure in high temperature restarting. Consequently, injection is carried out always in liquid condition and electric power consumption can be reduced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は液体燃料を吸気管に噴射してエンジンに供給する燃料噴射装置、殊に温度変化による圧力変動が大きく高温で気化しやすいＬＰＧを液体の状態で噴射させるための燃料噴射装置に関するものである。
【０００２】
【従来の技術】
液体燃料であるガソリンを吸気管に燃料噴射弁を用いて計量噴射しエンジンに供給するシステムは、図３に概略的に示したように燃料タンク５１に貯留されている液体燃料Ｆを燃料ポンプ５２で加圧し、供給管路５３より燃料ギャラリ５４に送ってエンジン５６の吸気管である吸気マニホルド各枝管に設置した燃料噴射弁５５に分配するようになっており、燃料噴射弁５５から枝管に噴射される液体燃料Ｆは圧力調整器５７で所定圧力に調整される。 また、燃料噴射弁５５から噴射されなかった余剰燃料は戻し管路５８を通って燃料タンク５１に戻される。
【０００３】
以上の燃料噴射装置は例えば特開昭５６−１３２４５４号公報、特開昭５８−３２９６４号公報に記載されているように周知である。一方、ガソリンに代えてＬＰＧを液体のまま燃料噴射弁より各枝管に噴射しエンジンに供給するものにおいても、例えば実開昭６１−１３８８６０号公報、実開昭６２−８７１６２号公報、特開昭６３−１８１７２号公報に記載されているように、基本的に前記ガソリンと同じ燃料噴射装置を使用している。
【０００４】
【発明が解決しようとする課題】
前記燃料噴射装置によりＬＰＧを液体の状態で噴射させようとした場合、ＬＰＧはガソリンに比べて温度変化による圧力変動がきわめて大きいので、例えば高温状態での低負荷運転が長時間続くと、燃料ギャラリ５４およびその付近でエンジン熱により加熱された大量の余剰燃料が燃料タンク５１に戻って循環し、燃料タンク５１内部の燃料温度および圧力を上昇させ気化させやすい状態を作る。 また、燃料タンク５１内の液体燃料Ｆが低温であっても、燃料ギャラリ５４およびその近くでエンジン熱で急激に加熱され高温となるので、殊に燃料ギャラリ５４の内部で不安定となって気相が発生しやすい状態となる。
【０００５】
更に、圧力調整器５７は予め調整した設定圧力に固定されており、燃料ポンプ５２は常に圧力調整器５７の設定圧力よりも高い圧力で液体燃料Ｆを吐出するように運転しなけらばならない。 加えて、液体燃料ＦがＬＰＧの場合は液体の状態を維持するために圧力または流量をガソリンよりも高くする必要があり、これらによって燃料ポンプ５２の駆動用電動機の電力消費量、即ちエンジンの電気負荷がきわめて大きい、という問題がある。
【０００６】
本発明は燃料タンクの液体燃料を燃料ポンプで加圧し圧力調整器で所定圧力に調整してエンジンの吸気管に設置した燃料噴射弁より噴射するとともに、余剰燃料を燃料タンクに戻すものとした従来の燃料噴射装置がもっているこれらの問題点を解決するためになされたものであって、燃料タンク内の燃料温度および圧力の上昇を招かないとともに、ＬＰＧのように気化しやすい燃料を安定した液体の状態で噴射することができ、しかも燃料ポンプ駆動のための電力消費量を低減できるものとすることを目的とする。
【０００７】
【課題を解決するための手段】
本発明は燃料ポンプを一段目燃料ポンプと二段目燃料ポンプとの二台として燃料タンクから燃料噴射弁に至る液体燃料の供給管路に直列設置し；圧力調整器は出口側圧力を噴射圧力設定用の背圧を使用するものとし、この圧力調整器を設置した余剰燃料の戻し管路を供給管路の二台の燃料ポンプの間の部分に接続した。そして、エンジンの通常運転時は余剰燃料を戻し管路から二段目燃料ポンプの入口側に導入するとともに燃料噴射弁からの噴射燃料分を燃料タンクから一段目燃料ポンプを通って補充させ、燃料噴射圧力を高くするときは一段目燃料ポンプを高吐出圧力運転して燃料噴射弁の入口側および圧力調整器の出口側の燃料圧力を高くする；ものとしたことをもって前期課題を解決するための第一手段とした。
【０００８】
また、本発明は第一手段における戻し管路の圧力調整器下流側から分岐して燃料タンクに接続された補助管路を設け、設定圧力以上の高圧燃料を燃料タンクに放出する高圧逃し弁を補助管路に設けた；ものとしたことをもって前期課題を解決するための第二手段とした。
【０００９】
通常運転時に余剰燃料は燃料タンクに戻ることなく二段目燃料ポンプから燃料噴射弁に送られ、更に圧力調整器を通って循環するので、高温状態で低負荷運転が長時間続くことがあっても燃料タンク内部の燃料温度および圧力を上昇させない。また、噴射燃料分のみが燃料タンクから補充されて二段目燃料ポンプの入口側で余剰燃料と合流するので、燃料噴射弁の入口付近で急激な加熱による不安定状態を生じさせることがなく、安定した液体の状態で噴射することができる。
【００１０】
高温再始動時のように液体の状態を維持させるため燃料噴射圧力を高くする必要があるときは、燃料噴射弁入口側および圧力調整器出口側の燃料圧力を高くすることにより、圧力調整器の前後圧力差を通常運転時と同じに保ちながら燃料噴射圧力を高くすることができる。 この場合、二段目燃料ポンプは通常運転時と同じ運転を行なわせ一段目燃料ポンプのみを一時的に高吐出圧力運転させるので、エンジンの全運転時間に亘る電力消費量を低減することができる。
【００１１】
以上は第一手段および第二手段に共通の作用、機能であるが、第二手段によるとエンジンが高温であって供給管路および戻し管路の燃料圧力が高圧となったときや、一段目燃料ポンプを高吐出圧力運転して戻し管路が高圧となったとき、高圧逃し弁が開いて設定圧力以上の高圧燃料を燃料タンクに放出し過度の高圧化を防止するため、配管破裂や機器類破損という事故を回避することができる。
【００１２】
【発明の実施の形態】
図面を参照して本発明の実施の形態を説明すると、異なる実施の形態を示す図１，図２において、燃料タンク１から燃料ギャラリ３に至る供給管路２に電動機駆動の一段目燃料ポンプ７と二段目燃料ポンプ８とが直列設置されている。燃料タンク１の液体燃料Ｆは供給管路２を通って燃料ギャラリ３に入り、エンジン５の吸気管である吸気マニホルドの枝管６のそれぞれに設置した燃料噴射弁４から噴射される。
【００１３】
燃料ギャラリ３から延びる戻し管路９は供給管路２の一段目燃料ポンプ７と二段目燃料ポンプ８との間の部分に接続されており、燃料噴射弁４からエンジン５に供給されなかった余剰の液体燃料Ｆはこの戻し管路９を通って二段目燃料ポンプ８の入口側に入るものとされている。
【００１４】
この戻し管路９に設置された圧力調整器１０はその下流側圧力を噴射圧力設定用の背圧とするものであり、調圧ばねのばね荷重と下流側圧力とによって上流側圧力である燃料ギャラリ３の液体燃料圧力を所定圧力に調整する。 また、戻し管路９の圧力調整器１０下流側の部分から分岐させて燃料タンク１に接続した補助管路１１が設けられており、燃料タンク１へ向かって開く逆止弁構造の高圧逃し弁１２が補助管路１１に設置されている。
【００１５】
二台の燃料ポンプ７、８は通常の燃料ポンプと同様であって、液体燃料の逆流を防止する逆止弁を吐出側に有している。また、二台の燃料ポンプ７、８の内で、殊に一段目燃料ポンプ７は高吐出圧力運転が可能な可変容量形のポンプが用いられるが、二段目燃料ポンプ８はエンジンの通常運転時に要求される圧力および流量を与える常用ポンプであって高吐出圧力運転は行なわない。 更に、エンジン５の運転状態を検知する各種センサからの信号に基いて燃料噴射弁４に所定のデューティサイクル信号を出力する周知の電子式制御装置１５が準備されており、この電子式制御装置１５は二台の燃料ポンプ７、８の駆動用電動機のそれぞれに所要の駆動信号を送るようになっている。
【００１６】
図１に示した実施の形態では、二台の燃料ポンプ７、８を燃料タンク１よりも低い位置に設置し、燃料タンク１に貯留されている液体燃料Ｆの液面と一段目燃料ポンプ７の入口との高さの差、即ちヘッド差Ｈによって液体燃料Ｆが一段目燃料ポンプ７に流入するようになっている。 尚、本実施の形態では二台の燃料ポンプ７、８を同一水平面上に配置し、それぞれの入口に高低差がないようにしている。
【００１７】
本実施の形態ではエンジン５の通常運転時に一段目燃料ポンプ７を運転することなく停止させておき、二段目燃料ポンプ８のみを運転するものであって、二段目燃料ポンプ８で加圧された液体燃料Ｆは燃料ギャラリ３に流入し圧力調整器１０により所定圧力に調整されて燃料噴射弁４から噴射しエンジン５に供給される。エンジン５に供給されなかった液体燃料Ｆは余剰燃料として戻し管路９を通り、二段目燃料ポンプ８の入口側に入って再び燃料ギャラリ３に送られる。
【００１８】
燃料噴射弁４から噴射することによって前述の循環経路内の液体燃料Ｆは減少するが、ヘッド差Ｈによって燃料タンク１から一段目燃料ポンプ７に流入した液体燃料Ｆがその隙間を通って供給管路２の戻し管路９合流箇所まで充満し余剰燃料と合流しているので、この燃料タンク１から落下流出した液体燃料Ｆにより噴射燃料分が余剰燃料に補充されて燃料ギャラリ３に送られることとなる。
【００１９】
このため、高温状態で低負荷運転が長時間続いて大量且つ高温の余剰燃料を発生しても、これが燃料タンク１に戻らないので燃料タンク１内部の燃料温度および圧力を上昇させることがない。 また、燃料タンク１内の低温の液体燃料Ｆが噴射燃料分ずつ高温の余剰燃料に加えられて燃料ギャラリ３に入るので、急激な加熱による気相を発生させやすい不安定状態を生じることがなく、ＬＰＧのように気化しやすい液体燃料を安定した液体の状態で噴射することができる。加えて、低温の液体燃料Ｆが噴射燃料分に応じて間断なく補充されることにより、循環する余剰燃料の温度上昇を抑制して気相発生を防止することができる。
【００２０】
次に、エンジン５の高温再始動時のように燃料噴射圧力を高くし液相の状態を確保して噴射させる必要のあるときは、エンジン始動に先立って一段目燃料ポンプ７を高吐出圧力運転するとともに、二段目燃料ポンプ８に通常運転時と同じ運転を行なわせる。このため、一段目燃料ポンプ７の吐出側圧力が上昇し、加圧された液体燃料Ｆは二段目燃料ポンプ８で更に加圧されて燃料ギャラリ３に入り、その一方で戻し管路９の圧力調整器１０下流側の圧力を上昇させる。燃料ギャラリ３の液体燃料圧力は一段目燃料ポンプ７の吐出圧力と二段目燃料ポンプ８の吐出圧力との和であり、圧力調整器１０の背圧は一段目燃料ポンプ７の吐出圧力である。
【００２１】
即ち、二段目燃料ポンプ８の吸入圧力が一段目燃料ポンプ７の吐出圧力分だけ高くなることにより、高い圧力で噴射することが可能となる。 また、圧力調整器１０の前後圧力差は通常運転時と同じであって、燃料噴射量を狂わせることがなく燃料噴射弁４の制御を容易且つ安定したものとする。
【００２２】
燃料ギャラリ３の燃料圧力が所定圧力となったとき、一段目燃料ポンプ７を停止して燃料噴射弁４から液体燃料Ｆを噴射してエンジン５を始動させる。エンジン５に供給されなかった液体燃料Ｆは戻し管路９を通り、二段目燃料ポンプ８の入口側に入って再び燃料ギャラリ３に送られることは通常運転時と同じであり、この高圧の液体燃料Ｆは一段目燃料ポンプ７の吐出側に逆止弁が設けられていることによって燃料タンク１に逆流することなく循環しながら燃料噴射弁４から噴射させられる。
【００２３】
高温再始動を終って前記の循環系内の燃料圧力が次第に低下し、二段目燃料ポンプ８の入口側圧力がヘッド差Ｈに相当する圧力となった後は、燃料タンク１の液体燃料Ｆが一段目燃料ポンプ７を通って余剰燃料に合流することにより、燃料噴射弁４からの噴射燃料分を補充するようになり、前述の通常運転に戻る。
【００２４】
以上により、高温再始動時のように液体燃料Ｆが気化しやすい状況のとき燃料噴射圧力を高くして液相の状態で噴射させること、および燃料ポンプ駆動の電力消費量を大幅に低減すること、が可能となる。
【００２５】
ここで、通常運転時に供給管路２、戻し管路９を通って循環する液体燃料Ｆがエンジン熱で加熱され高圧となったとき、或いは高温再始動時に一段目燃料ポンプ７を高吐出圧力運転することによって戻し管路９の液体燃料Ｆが高圧となったとき、本実施の形態では高圧逃し弁１２が開いて設定圧力以上の高圧燃料を補助管路１１より燃料タンク１に放出するようにしている。 このことにより、過度の高圧化が防止されて供給管路２、戻し管路９の破裂、圧力調整器１０などの機器類の破損、という事故を回避することができる。
【００２６】
図２に示した実施の形態では、一段目燃料ポンプ７を燃料タンク１の液体燃料Ｆに浸漬設置し、これより吐出管路２を燃料タンク１の上方へ延出させたものとしている。 本実施の形態では、エンジン５の通常運転時に燃料噴射弁４からの噴射燃料分を補充するように一段目燃料ポンプ７を小吐出量運転するものである。
【００２７】
そして、本実施の形態においても、余剰燃料は燃料タンク１に戻ることなく燃料ギャラリ３を通って循環することにより燃料タンク１内部の燃料温度および圧力を上昇させないこと、燃料タンク１内の低温の液体燃料Ｆを噴射燃料分ずつ二段目燃料ポンプ８の入口側で余剰燃料に加えることにより急激な加熱による不安定状態を生じさせないこと、低温の液体燃料Ｆが余剰燃料に間断なく補充されることにより温度上昇を抑制して気相発生を防止すること、という図１の実施の形態と同じ作用、機能を有するものである。
【００２８】
また、エンジン５の高温再始動時のように燃料噴射圧力を高くし液相の状態を確保する必要のあるときは一段目燃料ポンプ７を一時的に高吐出圧力運転することにより、燃料ギャラリ３の液体燃料圧力を一段目燃料ポンプ７の吐出圧力と二段目燃料ポンプ８の吐出圧力の和として高圧噴射可能にするとともに、圧力調整器１０の前後圧力差を通常運転時と同じとして燃料噴射弁４の制御を安定したものとすることができる。更に、高温再始動を終って前述の循環系内の燃料圧力が低下したとき、一段目燃料ポンプ７を小吐出量運転して噴射燃料分を補充させる、という通常運転を行なう。
【００２９】
以上により、本実施の形態においても高温再始動時のように液体燃料Ｆが気化しやすい状況のときに液相の状態で噴射させることができ、また燃料ポンプ駆動の電力消費量を低減することができ、加えて高圧逃し弁１２により供給管路２、戻し管路９や圧力調整器１０などの機器類を保護することができる、という図１の実施の形態と同様の作用、機能を有するものである。
【００３０】
【発明の効果】
以上のように、本発明によると余剰燃料を燃料タンクに戻さないことによって燃料タンク内の燃料温度および圧力の上昇がなくなり燃料気化の心配が解消されるとともに、高温再始動時のように燃料噴射圧力を高くし液体の状態を維持させる必要がある場合、ＬＰＧのように気化しやすい燃料を安定した液体の状態で噴射することができ、しかも燃料ポンプ駆動の電力消費量を低減することができるものである。 加えて、もう一つの本発明によると過度の高圧による配管破裂や機器類破損の危険が解消され、安全に使用することができるものである。
【図面の簡単な説明】
【図１】本発明の実施の形態を示す配置図。
【図２】本発明の異なる実施の形態を示す配置図。
【図３】従来例を示す配置図。
【符号の説明】
１ 燃料タンク、 ２ 供給管路、４ 燃料噴射弁、５ エンジン、７ 一段目燃料ポンプ、８ 二段目燃料ポンプ、９ 戻し管路、１０ 圧力調整器、１１補助管路、 １２ 高圧逃し弁、 １５ 電子式制御装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection device for injecting liquid fuel into an intake pipe and supplying the engine to an engine, and more particularly to a fuel injection device for injecting LPG, which has a large pressure fluctuation due to a temperature change and is likely to vaporize at a high temperature, in a liquid state. is there.
[0002]
[Prior art]
A system in which gasoline, which is liquid fuel, is metered into an intake pipe by using a fuel injection valve and supplied to an engine, uses a liquid pump F, which is stored in a fuel tank 51 as schematically shown in FIG. And feeds the fuel to the fuel gallery 54 from the supply pipe 53 and distributes the fuel to the fuel injection valves 55 installed in each branch pipe of the intake manifold, which is the intake pipe of the engine 56. Is adjusted to a predetermined pressure by the pressure regulator 57. Excess fuel not injected from the fuel injection valve 55 is returned to the fuel tank 51 through the return pipe 58.
[0003]
The above-described fuel injection device is well known, for example, as described in JP-A-56-132454 and JP-A-58-32964. On the other hand, in the case of injecting LPG as liquid instead of gasoline from a fuel injection valve into each branch pipe and supplying it to the engine, for example, Japanese Utility Model Laid-Open No. 61-138860, Japanese Utility Model Laid-Open No. 62-87162, As described in JP-A-63-18172, the same fuel injection device as the gasoline is basically used.
[0004]
[Problems to be solved by the invention]
When LPG is to be injected in a liquid state by the fuel injection device, pressure fluctuation due to temperature change of LPG is extremely large in LPG compared with gasoline. A large amount of surplus fuel heated by the engine heat in and around 54 returns to the fuel tank 51 and circulates, increasing the fuel temperature and pressure inside the fuel tank 51 to create a state in which the fuel is easily vaporized. Even if the temperature of the liquid fuel F in the fuel tank 51 is low, the fuel is rapidly heated to a high temperature by the engine heat in and near the fuel gallery 54 and becomes unstable especially in the fuel gallery 54. It is in a state where a phase is likely to occur.
[0005]
Further, the pressure regulator 57 is fixed at a preset pressure that has been adjusted in advance, and the fuel pump 52 must always be operated to discharge the liquid fuel F at a pressure higher than the pressure set by the pressure regulator 57. In addition, when the liquid fuel F is LPG, the pressure or the flow rate needs to be higher than that of gasoline in order to maintain the liquid state, and thus, the power consumption of the driving motor of the fuel pump 52, that is, the electric power of the engine, There is a problem that the load is extremely large.
[0006]
The present invention provides a conventional fuel tank in which liquid fuel in a fuel tank is pressurized by a fuel pump, adjusted to a predetermined pressure by a pressure regulator, injected from a fuel injection valve installed in an intake pipe of the engine, and returned to the fuel tank. In order to solve these problems of the fuel injection device, the fuel temperature and pressure in the fuel tank are not increased, and the fuel which is easily vaporized like LPG is stabilized by a liquid. It is an object of the present invention to be able to inject in the state described above, and to reduce the power consumption for driving the fuel pump.
[0007]
[Means for Solving the Problems]
In the present invention, the fuel pump is installed in series as a two-stage fuel pump of a first-stage fuel pump and a second-stage fuel pump in a supply line of the liquid fuel from the fuel tank to the fuel injection valve; A back pressure for setting the back pressure was used, and a return line for the excess fuel provided with the pressure regulator was connected to a portion of the supply line between the two fuel pumps. During normal operation of the engine, surplus fuel is introduced from the return line to the inlet side of the second-stage fuel pump, and fuel injected from the fuel injection valve is replenished from the fuel tank through the first-stage fuel pump. When increasing the injection pressure, the first-stage fuel pump is operated at a high discharge pressure to increase the fuel pressure on the inlet side of the fuel injection valve and on the outlet side of the pressure regulator. First means.
[0008]
Further, the present invention provides an auxiliary pipeline connected to the fuel tank by branching from the pressure regulator downstream side of the return pipeline in the first means, and a high-pressure relief valve for discharging high-pressure fuel having a set pressure or higher to the fuel tank. It was provided in the auxiliary pipeline; it was used as a second means to solve the problem in the previous term.
[0009]
During normal operation, surplus fuel is sent from the second-stage fuel pump to the fuel injection valve without returning to the fuel tank, and circulates through the pressure regulator. Also does not increase the fuel temperature and pressure inside the fuel tank. Also, since only the injected fuel is replenished from the fuel tank and merges with surplus fuel at the inlet side of the second stage fuel pump, an unstable state due to rapid heating near the inlet of the fuel injection valve does not occur, Injection can be performed in a stable liquid state.
[0010]
When it is necessary to increase the fuel injection pressure in order to maintain the liquid state, such as at the time of a high temperature restart, the fuel pressure at the fuel injection valve inlet side and the pressure regulator outlet side is increased to increase the pressure of the pressure regulator. The fuel injection pressure can be increased while maintaining the front-rear pressure difference the same as during normal operation. In this case, the second-stage fuel pump performs the same operation as in the normal operation, and only the first-stage fuel pump is temporarily operated at the high discharge pressure, so that the power consumption over the entire operation time of the engine can be reduced. .
[0011]
The above is the action and function common to the first means and the second means. However, according to the second means, when the engine temperature is high and the fuel pressure in the supply pipe and the return pipe becomes high, When the fuel pump is operated at a high discharge pressure and the return line becomes high pressure, the high pressure relief valve opens to release high pressure fuel at a pressure higher than the set pressure to the fuel tank and prevent excessive pressure buildup. It is possible to avoid accidents of class damage.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2 showing different embodiments, a first-stage fuel pump 7 driven by an electric motor is connected to a supply pipe 2 extending from a fuel tank 1 to a fuel gallery 3. And the second-stage fuel pump 8 are installed in series. The liquid fuel F in the fuel tank 1 enters the fuel gallery 3 through the supply pipe 2, and is injected from the fuel injection valve 4 installed in each of the intake manifold branch pipes 6 which are the intake pipes of the engine 5.
[0013]
The return line 9 extending from the fuel gallery 3 is connected to a portion between the first-stage fuel pump 7 and the second-stage fuel pump 8 of the supply line 2 and is not supplied from the fuel injection valve 4 to the engine 5. Excess liquid fuel F passes through the return line 9 and enters the inlet side of the second-stage fuel pump 8.
[0014]
The pressure regulator 10 installed in the return line 9 uses the downstream pressure as the back pressure for setting the injection pressure, and the fuel pressure which is the upstream pressure is determined by the spring load of the pressure adjusting spring and the downstream pressure. The liquid fuel pressure in the gallery 3 is adjusted to a predetermined pressure. Further, an auxiliary pipe 11 is provided which is branched from a portion of the return pipe 9 downstream of the pressure regulator 10 and is connected to the fuel tank 1. The high pressure relief valve has a check valve structure which opens toward the fuel tank 1. 12 is installed in the auxiliary pipeline 11.
[0015]
The two fuel pumps 7 and 8 are the same as ordinary fuel pumps, and have a check valve on the discharge side to prevent backflow of liquid fuel. Of the two fuel pumps 7, 8, a variable displacement pump capable of operating at a high discharge pressure is used as the first-stage fuel pump 7, in particular. It is a service pump that provides the pressure and flow rate required at times, and does not perform high discharge pressure operation. Further, a well-known electronic control unit 15 for outputting a predetermined duty cycle signal to the fuel injection valve 4 based on signals from various sensors for detecting the operation state of the engine 5 is provided. Is designed to send a required drive signal to each of the drive motors of the two fuel pumps 7 and 8.
[0016]
In the embodiment shown in FIG. 1, two fuel pumps 7 and 8 are installed at a position lower than the fuel tank 1 so that the liquid level of the liquid fuel F stored in the fuel tank 1 and the first-stage fuel pump 7 The liquid fuel F flows into the first stage fuel pump 7 due to the difference in height from the inlet of the first stage, that is, the head difference H. In the present embodiment, the two fuel pumps 7 and 8 are arranged on the same horizontal plane so that there is no difference in height between their inlets.
[0017]
In the present embodiment, during normal operation of the engine 5, the first-stage fuel pump 7 is stopped without operating, and only the second-stage fuel pump 8 is operated. The supplied liquid fuel F flows into the fuel gallery 3, is adjusted to a predetermined pressure by the pressure regulator 10, is injected from the fuel injection valve 4, and is supplied to the engine 5. The liquid fuel F that has not been supplied to the engine 5 passes through the return pipe 9 as surplus fuel, enters the inlet side of the second-stage fuel pump 8, and is sent to the fuel gallery 3 again.
[0018]
Injection from the fuel injection valve 4 reduces the amount of the liquid fuel F in the above-described circulation path. However, the head difference H causes the liquid fuel F flowing from the fuel tank 1 to the first-stage fuel pump 7 to pass through the gap to the supply pipe. Since the fuel is filled up to the junction of the return line 9 of the passage 2 and merged with the surplus fuel, the surplus fuel is replenished with the surplus fuel by the liquid fuel F that has fallen out of the fuel tank 1 and sent to the fuel gallery 3. It becomes.
[0019]
Therefore, even if a large amount of high-temperature surplus fuel is generated after long-time low-load operation in a high-temperature state, the fuel does not return to the fuel tank 1, so that the fuel temperature and pressure inside the fuel tank 1 do not increase. Further, since the low-temperature liquid fuel F in the fuel tank 1 is added to the high-temperature surplus fuel by the amount of the injected fuel and enters the fuel gallery 3, an unstable state in which a gas phase is easily generated by rapid heating does not occur. , LPG, which is easily vaporized, can be injected in a stable liquid state. In addition, since the low-temperature liquid fuel F is continuously replenished in accordance with the amount of the injected fuel, it is possible to suppress a rise in the temperature of the circulating surplus fuel and prevent the generation of a gas phase.
[0020]
Next, when it is necessary to increase the fuel injection pressure and maintain the liquid phase to perform injection, as in the case of restarting the engine 5 at a high temperature, the first-stage fuel pump 7 is operated at a high discharge pressure prior to engine start. At the same time, the second-stage fuel pump 8 is operated in the same manner as in the normal operation. For this reason, the discharge side pressure of the first stage fuel pump 7 increases, and the pressurized liquid fuel F is further pressurized by the second stage fuel pump 8 and enters the fuel gallery 3, while the return line 9 The pressure on the downstream side of the pressure regulator 10 is increased. The liquid fuel pressure of the fuel gallery 3 is the sum of the discharge pressure of the first-stage fuel pump 7 and the discharge pressure of the second-stage fuel pump 8, and the back pressure of the pressure regulator 10 is the discharge pressure of the first-stage fuel pump 7. .
[0021]
That is, when the suction pressure of the second-stage fuel pump 8 is increased by the discharge pressure of the first-stage fuel pump 7, it is possible to inject at a high pressure. The pressure difference between the front and rear of the pressure regulator 10 is the same as that in the normal operation, and the control of the fuel injection valve 4 is made easy and stable without changing the fuel injection amount.
[0022]
When the fuel pressure in the fuel gallery 3 reaches a predetermined pressure, the first-stage fuel pump 7 is stopped, and the liquid fuel F is injected from the fuel injection valve 4 to start the engine 5. The fact that the liquid fuel F not supplied to the engine 5 passes through the return line 9, enters the inlet side of the second-stage fuel pump 8, and is sent to the fuel gallery 3 again is the same as during normal operation. The liquid fuel F is injected from the fuel injection valve 4 while circulating without flowing back to the fuel tank 1 because the check valve is provided on the discharge side of the first-stage fuel pump 7.
[0023]
After the high-temperature restart, the fuel pressure in the circulation system gradually decreases, and after the pressure on the inlet side of the second-stage fuel pump 8 reaches a pressure corresponding to the head difference H, the liquid fuel F in the fuel tank 1 Merges with the surplus fuel through the first-stage fuel pump 7 to replenish the fuel injected from the fuel injection valve 4 and returns to the normal operation described above.
[0024]
As described above, when the liquid fuel F is liable to vaporize, such as at the time of high temperature restart, the fuel injection pressure is increased to perform the injection in the liquid phase, and the power consumption of driving the fuel pump is significantly reduced. , Becomes possible.
[0025]
Here, when the liquid fuel F circulating through the supply pipe 2 and the return pipe 9 during normal operation is heated by the engine heat to a high pressure, or when restarting at a high temperature, the first-stage fuel pump 7 is operated at a high discharge pressure. Thus, when the liquid fuel F in the return line 9 becomes high in pressure, in the present embodiment, the high pressure relief valve 12 is opened to discharge the high pressure fuel having a set pressure or more from the auxiliary line 11 to the fuel tank 1. ing. As a result, it is possible to prevent an excessive increase in pressure and to avoid an accident such as rupture of the supply line 2 and the return line 9 and breakage of devices such as the pressure regulator 10.
[0026]
In the embodiment shown in FIG. 2, the first-stage fuel pump 7 is immersed in the liquid fuel F of the fuel tank 1, and the discharge pipe 2 extends upward from the fuel tank 1. In the present embodiment, the first-stage fuel pump 7 is operated at a small discharge amount so as to replenish the fuel injected from the fuel injection valve 4 during the normal operation of the engine 5.
[0027]
Also in the present embodiment, the surplus fuel circulates through the fuel gallery 3 without returning to the fuel tank 1 so that the fuel temperature and the pressure inside the fuel tank 1 are not increased. By adding the liquid fuel F to the surplus fuel at the inlet side of the second-stage fuel pump 8 for each injected fuel, an unstable state due to rapid heating is not caused, and the low-temperature liquid fuel F is continuously replenished to the surplus fuel. This has the same function and function as the embodiment of FIG.
[0028]
When it is necessary to increase the fuel injection pressure and maintain the liquid phase state, as in the case of restarting the engine 5 at a high temperature, the fuel gallery 3 is operated by temporarily operating the first-stage fuel pump 7 at a high discharge pressure. High-pressure injection as the sum of the discharge pressure of the first-stage fuel pump 7 and the discharge pressure of the second-stage fuel pump 8 and the difference in pressure before and after the pressure regulator 10 is the same as during normal operation. The control of the valve 4 can be stabilized. Further, when the fuel pressure in the circulating system drops after the high-temperature restart, a normal operation of operating the first-stage fuel pump 7 with a small discharge amount to replenish the injected fuel is performed.
[0029]
As described above, in the present embodiment as well, it is possible to inject the liquid fuel F in the liquid phase when the liquid fuel F is likely to vaporize, such as during a high temperature restart, and to reduce the power consumption of driving the fuel pump. In addition, the high pressure relief valve 12 can protect equipment such as the supply line 2, the return line 9, and the pressure regulator 10, and has the same operation and function as the embodiment of FIG. Things.
[0030]
【The invention's effect】
As described above, according to the present invention, by not returning the surplus fuel to the fuel tank, the fuel temperature and the pressure in the fuel tank do not rise, so that the fear of fuel vaporization is eliminated, and the fuel injection as in the case of high temperature restart is performed. When it is necessary to maintain the liquid state by increasing the pressure, it is possible to inject the easily vaporizable fuel such as LPG in the stable liquid state, and to reduce the power consumption of the fuel pump drive. Things. In addition, according to another aspect of the present invention, the danger of rupture of piping and breakage of equipment due to excessively high pressure is eliminated, and the device can be used safely.
[Brief description of the drawings]
FIG. 1 is a layout diagram showing an embodiment of the present invention.
FIG. 2 is a layout diagram showing a different embodiment of the present invention.
FIG. 3 is a layout diagram showing a conventional example.
[Explanation of symbols]
1 fuel tank, 2 supply line, 4 fuel injection valve, 5 engine, 7 first stage fuel pump, 8 second stage fuel pump, 9 return line, 10 pressure regulator, 11 auxiliary line, 12 high pressure relief valve, 15 Electronic control unit

Claims (4)

燃料タンクの液体燃料を燃料ポンプで加圧し圧力調整器で所定圧力に調整して吸気管に設置した燃料噴射弁より噴射させエンジンに供給する燃料噴射装置において、
前記燃料ポンプは一段目燃料ポンプと二段目燃料ポンプとの二台であって、前記燃料タンクから前記燃料噴射弁に至る液体燃料の供給管路に直列設置されており、
前記圧力調整器は出口側圧力を噴射圧力設定用の背圧に使用するものであって、前記圧力調整器を設置した余剰燃料の戻し管路が前記供給管路の前記二台の燃料ポンプの間の部分に接続されており、
そして、エンジンの通常運転時は余剰燃料を前記戻し管路から前記二段目燃料ポンプの入口側に導入するとともに前記燃料噴射弁からの噴射燃料分を前記燃料タンクから前記一段目燃料ポンプを通って補充させ、燃料噴射圧力を高くするときは前記一段目燃料ポンプを高吐出圧力運転して前記燃料噴射弁の入口側および前記圧力調整器の出口側の燃料圧力を高くする、
ことを特徴とする燃料噴射装置。In a fuel injection device, a liquid fuel in a fuel tank is pressurized by a fuel pump, adjusted to a predetermined pressure by a pressure regulator, injected from a fuel injection valve installed in an intake pipe, and supplied to an engine.
The fuel pump is a two-stage fuel pump of the first stage and the second stage fuel pump, is installed in series in a supply line of liquid fuel from the fuel tank to the fuel injection valve,
The pressure regulator uses the outlet side pressure as the back pressure for setting the injection pressure, and the return line of the excess fuel in which the pressure regulator is installed is used for the two fuel pumps of the supply line. It is connected to the part between,
During normal operation of the engine, excess fuel is introduced from the return line to the inlet side of the second-stage fuel pump, and the amount of fuel injected from the fuel injection valve passes from the fuel tank through the first-stage fuel pump. When the fuel injection pressure is increased, the first-stage fuel pump is operated at a high discharge pressure to increase the fuel pressure on the inlet side of the fuel injection valve and the outlet side of the pressure regulator.
A fuel injection device characterized by the above-mentioned. 請求項１に記載した燃料噴射装置における前記戻し管路の前記圧力調整器下流側から分岐して前記燃料タンクに接続された補助管路が設けられ、設定圧力以上の高圧燃料を前記燃料タンクに放出する高圧逃し弁が前記補助管路に設置されている、
ことを特徴とする燃料噴射装置。The fuel injection device according to claim 1, wherein an auxiliary pipe branching from the downstream side of the pressure regulator of the return pipe and connected to the fuel tank is provided, and high-pressure fuel having a set pressure or more is supplied to the fuel tank. A high pressure relief valve for discharging is installed in the auxiliary line,
A fuel injection device characterized by the above-mentioned. 前記二台の燃料ポンプは前記燃料タンクよりも低位置に設置されており、前記一段目燃料ポンプはエンジンの通常運転時に運転を停止して前記燃料タンクの液体燃料を落差により通過させるものとされている請求項１または２に記載した燃料噴射装置。The two fuel pumps are installed at a lower position than the fuel tank, and the first-stage fuel pump stops operation during normal operation of the engine and passes the liquid fuel in the fuel tank by a head. The fuel injection device according to claim 1 or 2, wherein: 前記一段目燃料ポンプはエンジンの通常運転時に前記燃料噴射弁からの噴射燃料分を補充するように小吐出量運転し、燃料噴射圧力を高くするときに高吐出圧力運転するものとされている請求項１または２に記載した燃料噴射装置。The first-stage fuel pump is operated at a small discharge amount so as to replenish the fuel injected from the fuel injection valve during normal operation of the engine, and is operated at a high discharge pressure when the fuel injection pressure is increased. Item 3. The fuel injection device according to Item 1 or 2.
JP2003062833A 2003-03-10 2003-03-10 Fuel injection device Pending JP2004270560A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2003062833A JP2004270560A (en) 2003-03-10 2003-03-10 Fuel injection device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2003062833A JP2004270560A (en) 2003-03-10 2003-03-10 Fuel injection device

Publications (1)

Publication Number Publication Date
JP2004270560A true JP2004270560A (en) 2004-09-30

Family

ID=33124588

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2003062833A Pending JP2004270560A (en) 2003-03-10 2003-03-10 Fuel injection device

Country Status (1)

Country Link
JP (1) JP2004270560A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100639892B1 (en) 2005-08-31 2006-11-01 르노삼성자동차 주식회사 Liquid phase lpg injection fuel system for vehicle
WO2007049370A1 (en) * 2005-10-28 2007-05-03 Kazunori Yamamoto Petroleum fuel supply method and circuit
KR100728915B1 (en) 2006-06-21 2007-06-14 한국기계연구원 Gas feeding apparatus of gas fuel vehicles
JP2009097462A (en) * 2007-10-18 2009-05-07 Aisan Ind Co Ltd Fuel supply device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100639892B1 (en) 2005-08-31 2006-11-01 르노삼성자동차 주식회사 Liquid phase lpg injection fuel system for vehicle
WO2007049370A1 (en) * 2005-10-28 2007-05-03 Kazunori Yamamoto Petroleum fuel supply method and circuit
KR100728915B1 (en) 2006-06-21 2007-06-14 한국기계연구원 Gas feeding apparatus of gas fuel vehicles
JP2009097462A (en) * 2007-10-18 2009-05-07 Aisan Ind Co Ltd Fuel supply device

Similar Documents

Publication Publication Date Title
JP3743281B2 (en) Fuel supply device for internal combustion engine
US9212643B2 (en) Dual fuel system for an internal combustion engine
JP6600248B2 (en) Ship
JP6207731B2 (en) Fuel supply system for internal combustion engine
US8905006B2 (en) Diesel engine for a LPG-diesel mixture
US9394857B2 (en) Fuel system and corresponding method
RU2670642C9 (en) Heating device for a vehicle with a fuel hydraulic accumulator near the nozzle
JP4297907B2 (en) Liquefied gas fuel supply system for diesel engine
JP2006299838A (en) Fuel supply device for engine
JP2004270560A (en) Fuel injection device
JP3924716B2 (en) Accumulated fuel injection system
US20090211559A1 (en) Engine fuel supply circuit
JP2001349256A (en) Fuel supply system of internal combustion engine
JP5359472B2 (en) Fuel supply device
JP2008019719A (en) Storage device for liquefied gas fuel
WO2013115645A1 (en) Arrangement and method for bi-fuel combustion engines
KR102418127B1 (en) Fuel supply system for engine
JP2014202101A (en) Fuel supply system
JP4401004B2 (en) Engine liquefied gas fuel supply system
JP2004270558A (en) Fuel injector
JP4114147B2 (en) Engine liquid fuel supply system
JP2002004965A (en) Fuel injection device of internal combustion engine
JP2005180193A (en) Liquefied gas fuel supply device for diesel engine
JP2001115916A (en) Diesel engine for dimethyl ether
JP2004164153A (en) Pressure regulation device

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20060309

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20080311

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20080708