JP3446609B2 - Accumulator type fuel injection device - Google Patents

Accumulator type fuel injection device

Info

Publication number
JP3446609B2
JP3446609B2 JP15131498A JP15131498A JP3446609B2 JP 3446609 B2 JP3446609 B2 JP 3446609B2 JP 15131498 A JP15131498 A JP 15131498A JP 15131498 A JP15131498 A JP 15131498A JP 3446609 B2 JP3446609 B2 JP 3446609B2
Authority
JP
Japan
Prior art keywords
fuel
fuel injection
pressure
cylinder
pump
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.)
Expired - Fee Related
Application number
JP15131498A
Other languages
Japanese (ja)
Other versions
JPH11343896A (en
Inventor
豊 田内
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.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
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 Toyota Motor Corp filed Critical Toyota Motor Corp
Priority to JP15131498A priority Critical patent/JP3446609B2/en
Priority to EP99103574A priority patent/EP0962650B1/en
Priority to DE69925415T priority patent/DE69925415T2/en
Publication of JPH11343896A publication Critical patent/JPH11343896A/en
Application granted granted Critical
Publication of JP3446609B2 publication Critical patent/JP3446609B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/36—Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
    • F02M59/366—Valves being actuated electrically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/02—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type
    • F02M59/08—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps of reciprocating-piston or reciprocating-cylinder type characterised by two or more pumping elements with conjoint outlet or several pumping elements feeding one engine cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Description

【発明の詳細な説明】 【０００１】 【発明の属する技術分野】本発明は蓄圧式燃料噴射装置
に関する。 【０００２】 【従来の技術】従来より、各気筒の燃料噴射弁を共通の
蓄圧室に接続し、該蓄圧室に燃料ポンプの吐出側を接続
して燃料ポンプから蓄圧室内に燃料を圧送し、蓄圧室内
の燃料を燃料噴射弁から対応する気筒に供給するように
した蓄圧式燃料噴射装置が知られている。 【０００３】ところで、通常、各燃料噴射弁の燃料噴射
時間は同一とされる。したがって各気筒に供給される燃
料量のばらつきを低減するためには各燃料噴射が開始さ
れるときの蓄圧室内の燃料圧すなわち燃料噴射圧のばら
つきを低減する必要がある。一方、燃料噴射が行われる
と蓄圧室内の燃料圧が低下し、燃料圧送が行われると蓄
圧室内の燃料圧が高められる。そこで、燃料噴射が行わ
れる毎に燃料ポンプからの燃料圧送を行い、それにより
燃料噴射圧のばらつきができるだけ小さくなるようにし
た蓄圧式燃料噴射装置が公知である（特開平５−１０６
４９５号公報参照）。 【０００４】 【発明が解決しようとする課題】しかしながら、燃料噴
射が行われる毎に燃料圧送を行うためには気筒数と同数
のプランジャを燃料ポンプに設ける必要があり、その結
果燃料ポンプの寸法が大きくなるばかりでなく装置のコ
ストも増大するという問題点がある。一方、燃料ポンプ
の回転数を増大させるかあるいは燃料ポンプ１回転当た
りの燃料圧送回数を増大させればプランジャ数を低減す
ることができるが、この場合には燃料ポンプの耐久性が
低下する恐れがあるという問題点がある。 【０００５】 【課題を解決するための手段】前記課題を解決するため
に本発明によれば、各気筒の燃料噴射弁を共通の蓄圧室
に接続し、この蓄圧室に燃料ポンプの吐出側を接続して
燃料ポンプから蓄圧室内に燃料を圧送し、蓄圧室内の燃
料を燃料噴射弁から対応する気筒に供給するようにした
蓄圧式燃料噴射装置において、複数回の燃料噴射に対し
１回だけ燃料ポンプからの燃料圧送が行われるように、
かつ各燃料噴射が開始されるときの蓄圧室内の燃料圧の
ばらつきが予め定められた設定値よりも小さくなるよう
に、かつ燃料噴射時期と重なるように燃料噴射時期に対
する燃料ポンプの燃料圧送時期を定めている。すなわ
ち、複数回の燃料噴射に対し１回だけ燃料ポンプからの
燃料圧送が行われるので燃料ポンプの寸法およびコスト
が小さく維持されると共に燃料ポンプの耐久性が確保さ
れ、しかも燃料噴射時期に対する燃料ポンプの燃料圧送
時期を調節することによって燃料噴射圧のばらつきが小
さく維持される。 【０００６】 【発明の実施の形態】図１を参照すると、内燃機関本体
１は例えば４つの気筒＃１，＃２，＃３，＃４を備えて
いる。各気筒には筒内に燃料を直接噴射する燃料噴射弁
２が設けられる。各燃料噴射弁２は電磁式の燃料噴射弁
から形成され、電子制御ユニット４０から出力信号に基
づいて制御される。なお、本発明による実施態様におい
て各気筒の燃料噴射は＃１−＃３−＃４−＃２の順で行
われる。 【０００７】燃料噴射弁２の燃料通路は共通の蓄圧室す
なわちコモンレール３に接続され、コモンレール３は高
圧管４を介して燃料ポンプ５の吐出側に接続される。燃
料ポンプ５の吸入側は低圧管６を介して燃料タンク７内
に収容されたフィードポンプ８に接続される。なお、低
圧管６内には燃料フィルタ９が配置される。また、コモ
ンレール３から燃料タンク７までリターン管１０が延び
ており、このリターン管１０内にはコモンレール３から
燃料タンク７に向けてのみ流通可能な逆止弁１１が配置
される。逆止弁１１は通常閉弁しており、コモンレール
３内の燃料圧が過度に高くなったときに開弁してコモン
レール３内の燃料圧を低下せしめる。 【０００８】燃料ポンプ５は一対のプランジャ、すなわ
ち第１および第２のプランジャを備えた機関駆動式列型
ポンプから形成される。第１のプランジャを示す図２を
参照すると、２０はハウジング、２１はハウジング２０
内に形成されたプランジャ挿入孔、２２はプランジャ挿
入孔２１内に摺動可能に配置されたプランジャ、２３は
プランジャ２２を駆動するためのカム山を１つだけ備え
たカム、２４はプランジャ挿入孔２１内にプランジャ２
２により画定された高圧室、２５は連通孔２６を介して
高圧室２４と連通された低圧室、２７は連通孔２６の開
閉を制御するための燃料制御弁、２８は燃料制御弁２７
を制御するためのソレノイドコイルをそれぞれ示す。高
圧室２４は高圧通路２９を介して高圧管４に接続され、
高圧通路２９内には高圧室２４から高圧管４に向けての
み流通可能な逆止弁３０が配置される。低圧室２５は一
方では低圧通路３１を介して低圧管６に接続され、他方
ではリターン通路３２を介してリターン管１０に接続さ
れる。リターン通路３２内には低圧室２５からリターン
管１０に向けてのみ流通可能な逆止弁３３が配置され
る。なお、ソレノイドコイル２８は電子制御ユニット４
０からの出力信号に基づいて制御される。 【０００９】ソレノイドコイル２８が付勢されると燃料
制御弁２７が上昇せしめられ、その結果燃料制御弁２７
が閉弁される。これに対し、ソレノイドコイル２８が消
勢されると燃料制御弁２７が圧縮バネ３４により下降せ
しめられ、その結果燃料制御弁２７が開弁される。プラ
ンジャ２２が下降し始めると、このとき燃料制御弁２７
は開弁しているので低圧室２５内の燃料が連通孔２６を
介して高圧室２４内に流入する。次いでプランジャ２２
が下死点を過ぎて上昇し始めると圧送行程が開始される
が、圧送行程が開始されても燃料制御弁２７は開弁状態
に維持され、その結果高圧室２４内の燃料が連通孔２６
を介して低圧室２５に戻される。次いで燃料制御弁２７
が閉弁されると、高圧室２４内の燃料が高圧通路２９お
よび高圧管４を介してコモンレール３に圧送され始め
る。次いで、プランジャ２２が上死点になるとこの燃料
圧送が終了し、このとき燃料制御弁２７が開弁される。 【００１０】燃料ポンプ５からコモンレール３に圧送さ
れる燃料量を減少すべきときには燃料制御弁２７の閉弁
時期が遅められる。その結果、高圧室２４から低圧室２
５に戻る燃料量が増大し、斯くして高圧室２４から圧送
される燃料量が減少する。これに対し、燃料ポンプ５か
らコモンレール３に圧送される燃料量を増大すべきとき
には燃料制御弁２７の閉弁時期が早められる。その結
果、高圧室２４から低圧室２５に戻る燃料量が減少し、
斯くして高圧室２４から圧送される燃料量が増大する。
このように燃料制御弁２７の閉弁時期を制御することに
よって燃料ポンプ５からコモンレール３に圧送される燃
料量が制御される。なお、本発明による実施態様では燃
料噴射圧が目標燃料圧となるように燃料ポンプ５の燃料
圧送量が制御される。 【００１１】第１および第２のプランジャを駆動するた
めの一対のカムは共通のカム軸２３ａ上に形成され、こ
のカム軸２３ａは機関回転数の１／２の回転数でもって
回転せしめられる。各カムにはカム山が１つだけ形成さ
れており、その位相は３６０°クランク角（以下ＣＡと
称する）だけずれている。したがってクランクシャフト
（図示しない）が２回転すると第１のプランジャが１回
だけ燃料圧送を行い、第２のプランジャが１回だけ燃料
圧送を行い、このときこれら燃料圧送は３６０°ＣＡだ
けずれている。 【００１２】再び図１を参照すると、電子制御ユニット
（ＥＣＵ）４０はデジタルコンピュータからなり、双方
向性バス４１を介して相互に接続されたＲＯＭ（リード
オンリメモリ）４２、ＲＡＭ（ランダムアクセスメモ
リ）４３、ＣＰＵ（マイクロプロセッサ）４４、常時電
源に接続されているＢ−ＲＡＭ（バックアップＲＡＭ）
４５、入力ポート４６、および出力ポート４７を具備す
る。コモンレール３にはコモンレール３内の燃料圧に比
例した出力電圧を発生する圧力センサ４８が取り付けら
れる。また、アクセルペダル（図示しない）にはアクセ
ルペダルの踏み込み量に比例した出力電圧を発生する踏
み込み量センサ４９が取り付けられる。これらセンサ４
８，４９の出力電圧はそれぞれ対応するＡＤ変換器５０
を介して入力ポート４６に入力される。また、入力ポー
ト４６には機関回転数を表すパルスを発生する回転数セ
ンサ５１が接続される。一方、出力ポート４７はそれぞ
れ対応する駆動回路５２を介して燃料噴射弁２および燃
料ポンプ５のソレノイドコイル２８に接続される。 【００１３】ところで、冒頭で述べたように１回の燃料
噴射に対し燃料ポンプ５からの燃料圧送を１回だけ行う
ようにすると好ましくない。そこで本発明による実施態
様では、２回の燃料噴射に対し燃料圧送を１回だけ行う
ようにしている。すなわち、図１の内燃機関では７２０
°ＣＡ毎に燃料噴射が４回行われるので上述したように
３６０°ＣＡ毎に燃料圧送が１回だけ行われるようにす
ることによって２回の燃料噴射に対し燃料圧送が１回だ
け行われるように燃料圧送時期を定めている。その結
果、燃料ポンプ５の寸法およびコストを小さく維持する
ことができると共に燃料ポンプ５の耐久性を確保するこ
とができる。なお、本発明による実施態様では、燃料圧
送の時間間隔が燃料噴射の時間間隔よりも長くなるよう
に燃料圧送時期を定めているという見方もできる。 【００１４】ところが、燃料噴射回数に対する燃料圧送
回数をただ単に減少させると燃料噴射圧のばらつきが大
きくなり、その結果各気筒に供給される燃料量に大きな
ばらつきが生ずることになる。次に、このことについて
図３を参照して説明する。図３は好ましくない例におい
て、燃料噴射の実行（ＯＮ）および停止（ＯＦＦ）と、
コモンレール３内の燃料圧ＦＰと、燃料圧送の実行（Ｏ
Ｎ）および停止（ＯＦＦ）と、プランジャリフト量ＰＬ
とを示すタイムチャートである。なお、図３のプランジ
ャリフト量ＰＬにおいて実線は第１のプランジャのリフ
ト量を示しており、破線は第２のプランジャのリフト量
を示している。 【００１５】図３を参照するとこの例では、１番気筒＃
１の燃料噴射Ｉ１’が行われると燃料圧ＦＰが低下し、
次いで３番気筒＃３の燃料噴射Ｉ３’が行われると燃料
圧ＦＰがさらに低下する。次いで、燃料圧送Ｐ１’が行
われて燃料圧が上昇せしめられる。次いで、４番気筒＃
４の燃料噴射Ｉ４’が行われ、２番気筒＃２の燃料噴射
Ｉ２’が行われると燃料圧送Ｐ２’が行われる。次い
で、再び１番気筒＃１の燃料噴射Ｉ１’が行われ、３番
気筒＃３の燃料噴射Ｉ３’が行われると燃料圧送Ｐ１’
が行われる。 【００１６】この場合、図３に示されるように例えば１
番気筒＃１の燃料噴射圧と３番気筒＃３の燃料噴射圧と
の間には大きな差圧ＰＤ’が生じている。この差圧Ｐ
Ｄ’は各気筒の燃料噴射圧のばらつきを代表しており、
したがって図３に示す例では各気筒の燃料噴射圧に大き
なばらつきが生ずることになる。ところが、燃料噴射時
期に対する燃料圧送時期を調節することによって各気筒
の燃料噴射圧のばらつきを低減することができる。そこ
で本発明による実施態様では、各気筒の燃料噴射圧のば
らつきが小さくなるように燃料噴射時期に対する燃料圧
送時期を定めている。次に、図４を参照して本発明によ
る実施態様を詳細に説明する。 【００１７】図４は本発明による実施態様における図３
と同様なタイムチャートである。図４を参照すると本発
明による実施態様では、１番気筒＃１の燃料噴射Ｉ１が
行われると燃料圧ＦＰが低下する。次いで、燃料圧送Ｐ
１が開始される。次いで、３番気筒＃３の燃料噴射Ｉ３
が行われると燃料圧ＦＰが低下するが、このとき燃料圧
送Ｐ１が継続されており、このため３番気筒＃３の燃料
噴射Ｉ３が終了すると再び燃料圧ＦＰが上昇する。次い
で燃料圧送Ｐ１が終了すると燃料圧ＦＰが一定に維持さ
れる。次いで、４番気筒＃４の燃料噴射Ｉ４が行われ、
燃料圧送Ｐ２が開始された後に２番気筒＃２の燃料噴射
Ｉ２が開始される。２番気筒＃２の燃料噴射Ｉ２が終了
すると燃料圧送Ｐ２が終了する。 【００１８】この場合、例えば３番気筒の燃料噴射Ｉ３
が開始されるのに先立って燃料圧送Ｐ１が開始されるの
で３番気筒の燃料噴射圧を十分に高めることができ、３
番気筒の燃料噴射Ｉ３が終了した後燃料圧ＦＰが十分に
高くなってから燃料圧送Ｐ１が終了されるので後続の４
番気筒の燃料噴射圧を十分に高めることができる。その
結果、１番気筒＃１の燃料噴射圧と３番気筒＃３の燃料
噴射圧間の差圧ＰＤを小さく維持することができる。す
なわち、各気筒の燃料噴射圧のばらつきを低減すること
ができ、したがって各気筒に供給される燃料量のばらつ
きを低減することができる。また、各気筒に供給される
燃料量が正規の燃料量からずれるのを低減することがで
きる。 【００１９】本発明による実施態様では、各気筒の燃料
噴射圧のばらつきを代表する差圧ＰＤが予め定められた
設定値よりも小さくなるように燃料噴射時期に対する燃
料圧送時期を定めている。この設定値は例えば２から３
ＭＰａ程度である。なお、本発明による実施態様では、
１つおきの燃料噴射の燃料噴射時期と重なるように燃料
圧送時期を定めて燃料圧送が開始された後に燃料噴射が
開始され、燃料噴射が終了した後に燃料圧送が終了する
ようにし、燃料噴射が開始されるときの燃料圧ＦＰと燃
料圧送が終了したときの燃料圧ＦＰとのずれが設定値よ
りも小さくなるようにしているという見方もできる。し
かしながら、燃料圧送が開始された後に燃料噴射が開始
され、燃料圧送が終了した後に燃料噴射が終了するよう
にし、燃料噴射が開始されるときの燃料圧ＦＰと燃料噴
射が終了したときの燃料圧ＦＰとのずれが設定値よりも
小さくなるように燃料圧送時期を定めることもできる。
あるいは、燃料噴射が開始された後に燃料圧送が開始さ
れ、燃料噴射が終了した後に燃料圧送が終了するように
し、燃料噴射が開始されるときの燃料圧ＦＰと燃料圧送
が終了したときの燃料圧ＦＰとのずれが設定値よりも小
さくなるよう燃料圧送時期を定めることもできる。 【００２０】これまで述べてきた実施態様では、燃料ポ
ンプ５を一対のプランジャを備えた列型ポンプから形成
している。しかしながら、燃料ポンプ５を単一のプラン
ジャを備えたポンプ、分配型ポンプ、のほかあらゆる形
式のポンプから形成することもできる。 【００２１】 【発明の効果】燃料ポンプの寸法およびコストを小さく
維持することができると共に燃料ポンプの耐久性を確保
することができ、しかも燃料噴射が開始されるときの蓄
圧室内の燃料圧のばらつきを小さく維持することができ
る。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator type fuel injection device. [0002] Conventionally, a fuel injection valve of each cylinder is connected to a common accumulator, a discharge side of a fuel pump is connected to the accumulator, and fuel is pumped from the fuel pump into the accumulator. 2. Description of the Related Art There is known an accumulator-type fuel injection device in which fuel in an accumulator is supplied from a fuel injection valve to a corresponding cylinder. [0003] Usually, the fuel injection time of each fuel injection valve is the same. Therefore, in order to reduce the variation in the amount of fuel supplied to each cylinder, it is necessary to reduce the variation in the fuel pressure in the accumulator at the start of each fuel injection, that is, the variation in the fuel injection pressure. On the other hand, when the fuel injection is performed, the fuel pressure in the accumulator decreases, and when the fuel pumping is performed, the fuel pressure in the accumulator increases. Therefore, a pressure-accumulation type fuel injection device is known in which the fuel pumping is performed from the fuel pump every time fuel injection is performed so that the variation in the fuel injection pressure is reduced as much as possible (Japanese Patent Laid-Open No. 5-106).
495). [0004] However, in order to perform fuel pumping each time fuel injection is performed, it is necessary to provide the same number of plungers as the number of cylinders in the fuel pump. There is a problem that not only the size becomes large but also the cost of the device increases. On the other hand, the number of plungers can be reduced by increasing the number of revolutions of the fuel pump or increasing the number of times of fuel pumping per revolution of the fuel pump. However, in this case, the durability of the fuel pump may be reduced. There is a problem that there is. According to the present invention, a fuel injection valve of each cylinder is connected to a common accumulator, and a discharge side of a fuel pump is connected to the accumulator. In a pressure-accumulation type fuel injection device that is connected to pump fuel from a fuel pump into a pressure accumulation chamber and supply fuel from the pressure accumulation chamber to a corresponding cylinder from a fuel injection valve, the fuel is injected only once for a plurality of fuel injections. As fuel pumping from the pump is performed,
And the fuel pumping timing of the fuel pump to the fuel injection timing as variations in the accumulation chamber of the fuel pressure to be smaller than a predetermined set value, and overlaps with the fuel injection timing when the fuel injection is started It has established. That is, since the fuel pumping from the fuel pump is performed only once for a plurality of fuel injections, the size and cost of the fuel pump are kept small, the durability of the fuel pump is ensured, and the fuel pump with respect to the fuel injection timing is maintained. By adjusting the fuel pumping timing, the variation in the fuel injection pressure is kept small. Referring to FIG. 1, an internal combustion engine main body 1 includes, for example, four cylinders # 1, # 2, # 3, and # 4. Each cylinder is provided with a fuel injection valve 2 for directly injecting fuel into the cylinder. Each fuel injection valve 2 is formed of an electromagnetic fuel injection valve, and is controlled based on an output signal from the electronic control unit 40. In the embodiment according to the present invention, fuel injection of each cylinder is performed in the order of # 1- # 3- # 4- # 2. The fuel passage of the fuel injection valve 2 is connected to a common accumulator, that is, a common rail 3. The common rail 3 is connected to a discharge side of a fuel pump 5 via a high-pressure pipe 4. The suction side of the fuel pump 5 is connected via a low pressure pipe 6 to a feed pump 8 housed in a fuel tank 7. Note that a fuel filter 9 is disposed in the low-pressure pipe 6. A return pipe 10 extends from the common rail 3 to the fuel tank 7, and a check valve 11 that can flow only from the common rail 3 to the fuel tank 7 is disposed in the return pipe 10. The check valve 11 is normally closed, and opens when the fuel pressure in the common rail 3 becomes excessively high to decrease the fuel pressure in the common rail 3. The fuel pump 5 is formed from a pair of plungers, that is, an engine-driven row pump having first and second plungers. Referring to FIG. 2 showing the first plunger, reference numeral 20 denotes a housing, and 21 denotes a housing 20.
, A plunger slidably disposed in the plunger insertion hole 21, a cam 23 having only one cam ridge for driving the plunger 22, and a plunger insertion hole 24. Plunger 2 in 21
2, a low-pressure chamber 25 communicated with the high-pressure chamber 24 via a communication hole 26, a fuel control valve 27 for controlling the opening and closing of the communication hole 26, and a fuel control valve 27
Are shown, respectively, for controlling the solenoid coil. The high pressure chamber 24 is connected to the high pressure pipe 4 via a high pressure passage 29,
In the high-pressure passage 29, a check valve 30 that can flow only from the high-pressure chamber 24 to the high-pressure pipe 4 is arranged. The low-pressure chamber 25 is connected on the one hand to the low-pressure pipe 6 via a low-pressure passage 31 and on the other hand to the return pipe 10 via a return passage 32. In the return passage 32, a check valve 33 that can flow only from the low-pressure chamber 25 to the return pipe 10 is arranged. The solenoid coil 28 is connected to the electronic control unit 4.
It is controlled based on the output signal from 0. When the solenoid coil 28 is energized, the fuel control valve 27 is raised, with the result that the fuel control valve 27
Is closed. On the other hand, when the solenoid coil 28 is deenergized, the fuel control valve 27 is lowered by the compression spring 34, and as a result, the fuel control valve 27 is opened. When the plunger 22 starts to descend, the fuel control valve 27
Is open, the fuel in the low pressure chamber 25 flows into the high pressure chamber 24 through the communication hole 26. Then plunger 22
When the pressure starts to rise after passing through the bottom dead center, the pumping stroke is started. However, even when the pumping stroke is started, the fuel control valve 27 is kept open, and as a result, the fuel in the high-pressure chamber 24 passes through the communication hole 26.
Is returned to the low-pressure chamber 25 via. Next, the fuel control valve 27
Is closed, the fuel in the high-pressure chamber 24 starts to be fed to the common rail 3 via the high-pressure passage 29 and the high-pressure pipe 4. Next, when the plunger 22 reaches the top dead center, the fuel pumping ends, and at this time, the fuel control valve 27 is opened. When the amount of fuel pumped from the fuel pump 5 to the common rail 3 is to be reduced, the closing timing of the fuel control valve 27 is delayed. As a result, from the high pressure chamber 24 to the low pressure chamber 2
The amount of fuel returning to 5 increases, and thus the amount of fuel pumped from the high pressure chamber 24 decreases. On the other hand, when the amount of fuel pumped from the fuel pump 5 to the common rail 3 is to be increased, the closing timing of the fuel control valve 27 is advanced. As a result, the amount of fuel returning from the high pressure chamber 24 to the low pressure chamber 25 decreases,
Thus, the amount of fuel pumped from the high-pressure chamber 24 increases.
By controlling the closing timing of the fuel control valve 27 in this manner, the amount of fuel pumped from the fuel pump 5 to the common rail 3 is controlled. In the embodiment according to the present invention, the fuel pumping amount of the fuel pump 5 is controlled so that the fuel injection pressure becomes the target fuel pressure. A pair of cams for driving the first and second plungers are formed on a common camshaft 23a, and this camshaft 23a is rotated at half the engine speed. Each cam is formed with only one cam peak, and its phase is shifted by 360 ° crank angle (hereinafter referred to as CA). Therefore, when the crankshaft (not shown) makes two rotations, the first plunger performs fuel pumping only once and the second plunger performs fuel pumping only once, and the fuel pumping is shifted by 360 ° CA. . Referring again to FIG. 1, the electronic control unit (ECU) 40 is composed of a digital computer, and is connected to a ROM (Read Only Memory) 42 and a RAM (Random Access Memory) interconnected via a bidirectional bus 41. 43, CPU (microprocessor) 44, B-RAM (backup RAM) always connected to power supply
45, an input port 46, and an output port 47. A pressure sensor 48 that generates an output voltage proportional to the fuel pressure in the common rail 3 is attached to the common rail 3. Further, a depression amount sensor 49 for generating an output voltage proportional to the depression amount of the accelerator pedal is attached to the accelerator pedal (not shown). These sensors 4
8 and 49 are output from the corresponding AD converters 50, respectively.
Through the input port 46. The input port 46 is connected to a rotation speed sensor 51 that generates a pulse representing the engine rotation speed. On the other hand, the output ports 47 are connected to the fuel injection valve 2 and the solenoid coil 28 of the fuel pump 5 via the corresponding drive circuits 52, respectively. Incidentally, as described at the beginning, it is not preferable to perform the fuel pumping from the fuel pump 5 only once for one fuel injection. Therefore, in the embodiment according to the present invention, the fuel pumping is performed only once for two fuel injections. That is, in the internal combustion engine of FIG.
Since the fuel injection is performed four times per ° CA, the fuel pumping is performed only once every 360 ° CA as described above, so that the fuel pumping is performed only once for two fuel injections. The fuel pumping time is specified in As a result, the size and cost of the fuel pump 5 can be kept small, and the durability of the fuel pump 5 can be ensured. In the embodiment according to the present invention, it can be seen that the fuel pumping time is determined so that the fuel pumping time interval is longer than the fuel injection time interval. However, if the number of times of fuel pumping with respect to the number of times of fuel injection is simply reduced, the dispersion of the fuel injection pressure increases, and as a result, the amount of fuel supplied to each cylinder greatly varies. Next, this will be described with reference to FIG. FIG. 3 shows, in an unfavorable example, the execution (ON) and stop (OFF) of fuel injection,
Execution of fuel pressure FP in the common rail 3 and fuel pressure feed (O
N), stop (OFF) and plunger lift PL
FIG. Note that, in the plunger lift amount PL of FIG. 3, the solid line indicates the lift amount of the first plunger, and the broken line indicates the lift amount of the second plunger. Referring to FIG. 3, in this example, the first cylinder #
When the first fuel injection I1 'is performed, the fuel pressure FP decreases,
Next, when the fuel injection I3 'of the third cylinder # 3 is performed, the fuel pressure FP further decreases. Next, the fuel pressure P1 'is performed to increase the fuel pressure. Next, # 4 cylinder
4 is performed, and when the fuel injection I2 'of the second cylinder # 2 is performed, the fuel pumping P2' is performed. Next, the fuel injection I1 'of the first cylinder # 1 is performed again, and when the fuel injection I3' of the third cylinder # 3 is performed, the fuel pumping P1 'is performed.
Is performed. In this case, as shown in FIG.
A large pressure difference PD ′ is generated between the fuel injection pressure of the # 1 cylinder and the fuel injection pressure of the # 3 cylinder # 3. This differential pressure P
D 'represents the variation of the fuel injection pressure of each cylinder,
Therefore, in the example shown in FIG. 3, a large variation occurs in the fuel injection pressure of each cylinder. However, by adjusting the fuel injection timing with respect to the fuel injection timing, it is possible to reduce the variation in the fuel injection pressure of each cylinder. Therefore, in the embodiment according to the present invention, the fuel pumping timing with respect to the fuel injection timing is determined so that the variation in the fuel injection pressure of each cylinder is reduced. Next, an embodiment according to the present invention will be described in detail with reference to FIG. FIG. 4 shows an embodiment according to the present invention.
It is a time chart similar to. Referring to FIG. 4, in the embodiment according to the present invention, the fuel pressure FP decreases when the fuel injection I1 of the first cylinder # 1 is performed. Next, the fuel pressure P
1 is started. Next, the fuel injection I3 of the third cylinder # 3
Is performed, the fuel pressure FP decreases. At this time, the fuel pressure feed P1 is continued. Therefore, when the fuel injection I3 of the third cylinder # 3 ends, the fuel pressure FP increases again. Next, when the fuel pumping P1 is completed, the fuel pressure FP is kept constant. Next, fuel injection I4 of the fourth cylinder # 4 is performed,
After the fuel pumping P2 is started, the fuel injection I2 of the second cylinder # 2 is started. When the fuel injection I2 of the second cylinder # 2 ends, the fuel pressure feeding P2 ends. In this case, for example, the fuel injection I3 of the third cylinder
Is started before the start of the fuel injection, the fuel injection pressure of the third cylinder can be sufficiently increased.
After the fuel injection I3 of the number-th cylinder ends, the fuel pressure FP becomes sufficiently high and then the fuel pumping P1 ends.
It is possible to sufficiently increase the fuel injection pressure of the cylinder number. As a result, the pressure difference PD between the fuel injection pressure of the first cylinder # 1 and the fuel injection pressure of the third cylinder # 3 can be kept small. That is, variations in the fuel injection pressure of each cylinder can be reduced, and therefore variations in the amount of fuel supplied to each cylinder can be reduced. In addition, it is possible to reduce deviation of the fuel amount supplied to each cylinder from the regular fuel amount. In the embodiment according to the present invention, the fuel pumping timing with respect to the fuel injection timing is determined so that the differential pressure PD representing the variation in the fuel injection pressure of each cylinder becomes smaller than a predetermined set value. This setting value is, for example, 2 to 3
It is on the order of MPa. In the embodiment according to the present invention,
The fuel injection timing is determined so as to coincide with the fuel injection timing of every other fuel injection, the fuel injection is started after the fuel injection is started, and the fuel injection is ended after the fuel injection is completed. It can also be seen that the difference between the fuel pressure FP at the start and the fuel pressure FP at the end of the fuel pumping is smaller than a set value. However, the fuel injection is started after the fuel pumping is started, and the fuel injection is finished after the fuel pumping is finished. The fuel pressure FP when the fuel injection is started and the fuel pressure when the fuel injection is finished. The fuel pumping time may be determined so that the deviation from the FP is smaller than the set value.
Alternatively, the fuel pumping is started after the fuel injection is started, and the fuel pumping is ended after the fuel injection is finished, so that the fuel pressure FP when the fuel injection is started and the fuel pressure when the fuel pumping is finished. The fuel pumping time can be determined so that the deviation from the FP is smaller than the set value. In the embodiments described above, the fuel pump 5 is formed from a row type pump having a pair of plungers. However, the fuel pump 5 can also be formed from a pump with a single plunger, a distribution pump or any other type of pump. According to the present invention, the size and cost of the fuel pump can be kept small, the durability of the fuel pump can be secured, and the fuel pressure in the accumulator at the time of starting the fuel injection can be varied. Can be kept small.

【図面の簡単な説明】 【図１】内燃機関の全体図である。 【図２】燃料ポンプの断面図である。 【図３】好ましくない例を説明するためのタイムチャー
トである。 【図４】本発明による実施態様を説明するためのタイム
チャートである。 【符号の説明】 １…機関本体 ２…燃料噴射弁 ３…コモンレール ５…燃料ポンプBRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view of an internal combustion engine. FIG. 2 is a sectional view of a fuel pump. FIG. 3 is a time chart for explaining an undesirable example. FIG. 4 is a time chart for explaining an embodiment according to the present invention. [Description of Signs] 1 ... Engine main body 2 ... Fuel injection valve 3 ... Common rail 5 ... Fuel pump

Claims (1)

(57)【特許請求の範囲】 【請求項１】 各気筒の燃料噴射弁を共通の蓄圧室に接
続し、該蓄圧室に燃料ポンプの吐出側を接続して燃料ポ
ンプから蓄圧室内に燃料を圧送し、蓄圧室内の燃料を燃
料噴射弁から対応する気筒に供給するようにした蓄圧式
燃料噴射装置において、複数回の燃料噴射に対し１回だ
け燃料ポンプからの燃料圧送が行われるように、かつ各
燃料噴射が開始されるときの蓄圧室内の燃料圧のばらつ
きが予め定められた設定値よりも小さくなるように、か
つ燃料噴射時期と重なるように燃料噴射時期に対する燃
料ポンプの燃料圧送時期を定めた蓄圧式燃料噴射装置。(57) [Claims 1] A fuel injection valve of each cylinder is connected to a common accumulator, a discharge side of a fuel pump is connected to the accumulator, and fuel is supplied from the fuel pump into the accumulator. In a pressure-accumulation type fuel injection device that performs pressure feeding and supplies fuel in a pressure storage chamber from a fuel injection valve to a corresponding cylinder, fuel pressure feeding from a fuel pump is performed only once for a plurality of fuel injections. And so that the variation in the fuel pressure in the accumulator at the start of each fuel injection is smaller than a predetermined set value .
An accumulator-type fuel injection device in which the fuel pumping timing of the fuel pump with respect to the fuel injection timing is determined so as to overlap with the fuel injection timing.
JP15131498A 1998-06-01 1998-06-01 Accumulator type fuel injection device Expired - Fee Related JP3446609B2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP15131498A JP3446609B2 (en) 1998-06-01 1998-06-01 Accumulator type fuel injection device
EP99103574A EP0962650B1 (en) 1998-06-01 1999-02-24 Accumulator-type fuel injection apparatus and control method for the same
DE69925415T DE69925415T2 (en) 1998-06-01 1999-02-24 Accumulator fuel injection device and control method therefor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP15131498A JP3446609B2 (en) 1998-06-01 1998-06-01 Accumulator type fuel injection device

Publications (2)

Publication Number Publication Date
JPH11343896A JPH11343896A (en) 1999-12-14
JP3446609B2 true JP3446609B2 (en) 2003-09-16

Family

ID=15515945

Family Applications (1)

Application Number Title Priority Date Filing Date
JP15131498A Expired - Fee Related JP3446609B2 (en) 1998-06-01 1998-06-01 Accumulator type fuel injection device

Country Status (3)

Country Link
EP (1) EP0962650B1 (en)
JP (1) JP3446609B2 (en)
DE (1) DE69925415T2 (en)

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Publication number Priority date Publication date Assignee Title
KR100612784B1 (en) * 2002-01-31 2006-08-17 가부시키가이샤 덴소 Accumulator injection system
ITBO20040323A1 (en) * 2004-05-20 2004-08-20 Magneti Marelli Powertrain Spa METHOD OF DIRECT INJECTION OF FUEL INTO AN INTERNAL COMBUSTION ENGINE
ITBO20040322A1 (en) 2004-05-20 2004-08-20 Magneti Marelli Powertrain Spa METHOD AND SYSTEM FOR DIRECT FUEL INJECTION INTO AN INTERNAL COMBUSTION ENGINE
DE102008050060A1 (en) * 2008-10-01 2010-04-08 Man Diesel Se Common-rail fuel injection system for combustion engine, particularly marine diesel engine, has fuel reservoir and high pressure reservoir for filling of combustion chambers of combustion engine
DE102014208558A1 (en) * 2014-05-07 2015-11-12 Robert Bosch Gmbh Injection system and method for operating an injection molding system
JP6973010B2 (en) * 2017-12-13 2021-11-24 トヨタ自動車株式会社 Fuel pump controller

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5058553A (en) * 1988-11-24 1991-10-22 Nippondenso Co., Ltd. Variable-discharge high pressure pump
JPH05106495A (en) 1991-10-15 1993-04-27 Nippondenso Co Ltd Accumulator type fuel injection device for internal combustion engine
US6142125A (en) * 1997-08-22 2000-11-07 Isuzu Motors Limited Supply pump for common rail fuel injection system

Also Published As

Publication number Publication date
DE69925415T2 (en) 2006-02-02
DE69925415D1 (en) 2005-06-30
EP0962650A2 (en) 1999-12-08
EP0962650B1 (en) 2005-05-25
EP0962650A3 (en) 2003-03-05
JPH11343896A (en) 1999-12-14

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