JP3598780B2

JP3598780B2 - Fuel injection device for internal combustion engine

Info

Publication number: JP3598780B2
Application number: JP33202297A
Authority: JP
Inventors: 勉菊池
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 1997-12-02
Filing date: 1997-12-02
Publication date: 2004-12-08
Anticipated expiration: 2017-12-02
Also published as: JPH11166462A

Description

【０００１】
【発明の属する技術分野】
本発明は、内燃機関の燃料噴射装置に関し、特に、燃料の気化性を向上するべく、燃料噴射弁にて燃料を加熱する機能を有する燃料噴射装置に関する。
【０００２】
【従来の技術】
内燃機関の各気筒毎に燃料噴射弁を設けた電子制御式燃料噴射装置が広く用いられているが、例えば、始動時を含む低温の運転条件及び機関の所定回転速度未満かつ所定負荷未満の運転条件では、燃料噴射弁から噴射された燃料の気化が不十分であるため、燃料と空気との混合性が悪く、始動性の悪化、燃焼安定性の低下を来し、排気性能、燃費が悪化する等の問題がある。
【０００３】
このため、従来、燃料を加熱させて気化性を向上する技術が種々提案されている。
例えば、特開昭６３−１７０５５５号公報には、燃料噴射弁における噴孔の形成してある部材に、ヒータを設け、ヒータにより前記部材を加熱して、噴孔を通過する燃料及び噴孔に至る直前の燃料噴射弁内の燃料を加温する技術が開示されている。
【０００４】
又、特開平７−８３０９１号公報には、内燃機関の寒冷時の始動性を向上するべく、燃料噴射弁が開放されない程度に短い開放信号を燃料噴射弁に与えて、燃料噴射弁を加熱して、弁芯部、弁座部等の氷結を除去する技術が開示されている。
更に、特開平５−３９８８３号公報には、燃料噴射弁の電磁コイルに高周波電流を通電し、電磁コイルの内部に設けられた部材を磁気誘導発熱させることにより、燃料噴射弁を加熱して、燃料を加熱する技術が開示されている。
【０００５】
【発明が解決しようとする課題】
しかしながら、上述の各技術にあっては、夫々次のような問題点がある。
即ち、特開昭６３−１７０５５５号公報の技術にあっては、燃料噴射弁における噴孔の形成してある部材に、ヒータを設ける構成であるため、即ち、燃料噴射弁にこれの構成部材とは別の部材を付加する構成であるため、燃料噴射弁の構造が複雑化すると共に大型化を来し、取付性に支障を来す。
【０００６】
又、燃料とヒータにより加熱される部材との接触面も大きいとは言えず、伝熱効率が悪く、燃料の加熱性が低い。
特開平７−８３０９１号公報の技術にあっては、燃料噴射弁の開放時間は燃料を噴射しないだけの短い時間（例えば５ｍｓ程度）であるため、燃料噴射させずに燃料を有効に加熱するだけの時間がなく、十分な効果が得られない。
【０００７】
特開平５−３９８８３号公報の技術にあっては、燃料噴射弁の電磁コイルに高周波電流を通電する高周波電源を設ける必要があるため、コスト的に問題がある。
そこで、本発明は以上のような従来の問題点に鑑み、燃料の気化性を向上するべく、燃料噴射弁にて燃料を加熱する機能を有する燃料噴射装置であって、燃料噴射弁自体の構造の複雑化、大型化、コスト高等の不都合を生じさせない簡単な構成により、十分な燃料加熱効果を得られる内燃機関の燃料噴射装置を提供することを目的とする。
【０００８】
【課題を解決するための手段】
このため、請求項１に係る発明は、
燃料の通路を開閉する弁体と、弁体を駆動する可動鉄心と、電磁コイルと、を含んで構成された燃料噴射弁と、前記電磁コイルへの駆動電流を断続する断続手段を備えた駆動回路と、を含んで構成され、前記電磁コイルへの駆動電流供給により発生した電磁力によって、可動鉄心を吸引して前記弁体を開弁駆動する構成の内燃機関の燃料噴射装置において、
前記駆動回路に、前記電磁コイルにその駆動電流とは逆方向の電流を供給する逆電流供給手段を設け、
前記逆電流供給手段は、１つのサイクルにおいて、燃料の噴射域が設定される機関の行程以外の行程で、前記逆方向の電流を供給することを特徴とする。
【０００９】
請求項２に係る発明は、
機関の所定運転状態を判定する手段と、
燃料の噴射時期と、前記噴射域以外の領域に設定される燃料の非噴射域における非噴射時期とを判定する手段と、
前記駆動回路に設けられ、両判定手段からの判定結果に基づいて、機関の所定運転状態でかつ燃料の非噴射時期であるときに、前記電磁コイルにその駆動電流とは逆方向の電流を供給し、機関の所定運転状態でかつ燃料の噴射時期であるときに、前記電磁コイルにその駆動電流を供給するべく、前記断続手段と逆電流供給手段とを制御する制御回路と、
を含んで構成したことを特徴とする。
【００１０】
請求項３に係る発明は、
前記機関の所定運転状態は、機関の始動を含む低温の運転条件であることを特徴とする。
請求項４に係る発明は、
前記機関の所定運転状態は、機関の所定回転速度未満かつ所定負荷未満の運転条件であることを特徴とする。
【００１１】
請求項５に係る発明は、
前記逆電流供給手段は、電磁コイルに印加する電圧を正・逆に反転切換して、電磁コイルに駆動電流と該駆動電流と逆方向の電流を供給する電圧反転器からなることを特徴とする。
かかる本発明の作用について説明する。
【００１２】
請求項１に係る発明において、燃料噴射弁における弁体駆動用の電磁コイルと、電磁コイルにその駆動電流とは逆方向の電流を供給する逆電流供給手段と、を用いた簡単な構成により、燃料が加熱される。逆電流供給手段は、１つのサイクルにおいて、燃料の噴射域が設定される機関の行程以外の行程で、この逆方向の電流を供給する。
このように加熱された燃料の噴霧は気化が促進されかつその粒径が細かくなるため、燃料と吸入空気との混合性が向上し、均一混合気を機関に供給できるため、完全燃焼を行わせることができる。
【００１３】
この結果、低温始動性等の向上を図ることができると共に、排気性能の向上、燃費の向上等を図ることができる。
請求項２に係る発明において、機関の所定運転状態でかつ燃料の非噴射時期であるときに、電磁コイルにその駆動電流とは逆方向の電流が供給され、燃料が加熱される。
【００１４】
この場合、電磁コイルの開弁動作には影響がない逆電流を流してこれを加熱するため、燃料噴射させずに燃料を有効に加熱する時間が、燃料の非噴射時期において、大きくとることが可能であり、十分な燃料加熱効果が得られる。
請求項３に係る発明において、機関の始動を含む低温の運転条件で燃料が加熱され、この運転条件において、燃料噴射弁から噴射された燃料の気化が十分となり、燃料と空気との混合性が向上し、機関の始動性及び燃焼安定性の向上が図られる。
【００１５】
ここで、機関の高回転・高負荷の運転条件では、燃料流量自体が多量であり、これらの運転条件では、燃料の加熱を行う割りに効果代が少なく、電磁コイル用の電力消費量が浪費されるに過ぎず、かつ機関の燃焼温度そのものが高くなるため、燃料の気化促進・微粒化の必要性が少ない。
従って、請求項４に係る発明においては、機関の所定回転速度未満かつ所定負荷未満の運転条件で、燃料が加熱され、この運転条件において、燃料噴射弁から噴射された燃料の気化が十分となり、燃料と空気との混合性が向上し、機関の燃焼安定性の向上が図られ、機関の高回転・高負荷の運転条件では、燃料の加熱が停止されるため、電磁コイル用の電力消費量の無駄な浪費が防止され、燃料を有効的に加熱することができると共に、燃費性能の悪化を未然に防止することができる。
【００１６】
請求項５に係る発明において、電圧反転器によって、電磁コイルが通常の燃料噴射制御状態と、燃料加熱制御状態と、に容易に切り換えられる。
【００１７】
【発明の効果】
請求項１に係る発明によれば、燃料の気化性を向上することができ、排気性能の向上、燃費の向上等を図ることができると共に、燃料噴射弁自体には、これの構成部材とは別の部材を付加する必要がないため、燃料噴射弁の構造の複雑化、大型化を来すことがなく、取付性にも支障を来すことがなく、コスト的にも有利である。又、燃料と電磁コイルの加熱によって加熱される部分との接触面積が大きいため、伝熱効率が良く、燃料の加熱性が高い。更に、電磁コイルの開弁動作には影響がない逆電流を流してこれを加熱するため、燃料噴射させずに燃料を有効に加熱する時間を大きくとることが可能であり、十分な燃料加熱効果が得られる。
【００１８】
請求項２に係る発明によれば、燃料を有効に加熱する時間が、燃料の非噴射時期において、大きくとることが可能であり、所定運転状態において、十分な燃料加熱効果を得ることができる。
請求項３に係る発明によれば、機関の始動を含む低温の運転条件において、機関の始動性及び燃焼安定性の向上を図ることができる。
【００１９】
請求項４に係る発明によれば、機関の所定回転速度未満かつ所定負荷未満の運転条件において、燃焼安定性の向上を図れ、特に、機関の高回転・高負荷の運転条件では、燃料の加熱が停止されるため、電磁コイル用の電力消費量の無駄な浪費が防止され、燃料を有効的に加熱することができる。
請求項５に係る発明によれば、電圧反転器の適用により、電磁コイルを、通常の燃料噴射制御状態と、燃料加熱制御状態と、に容易に切り換えることができ、簡単な構造で、燃料加熱機能を有する燃料噴射装置を提供できる。
【００２０】
【発明の実施の形態】
以下、添付された図面を参照して本発明を詳述する。
先ず、図２に基づいて、本発明の対象とする燃料噴射弁の一実施形態の構成について説明する。
この図において、磁性材料からなるバルブハウジング１には、非磁性材料からなるボビン２が内挿され、このボビン２には、電磁コイル５が巻回されている。
【００２１】
前記バルブハウジング１内には、可動鉄心３が挿入され、この可動鉄心３には弁体としてのニードル４が結合されている。
更に、バルブハウジング１の先端部には、スペーサ７ａを介してノズルボディ７が設けられており、前記ニードル４は、スペーサ７ａを貫通して、ノズルボディ７の内周面で支持され、ニードル４の先端部は、ノズルボディ７の先端部に形成された噴孔７ｂを閉じている。
【００２２】
前記電磁コイル５は電極端子８に接続されており、燃料噴射弁の駆動回路９とリード線１０により接続されている。
そして、駆動回路９は、図１に示すように、制御回路９Ａと、該制御回路９Ａからの制御信号によりＯＮ・ＯＦＦ制御される断続手段としてのパワートランジスタ９Ｂと制御回路９Ａからの制御信号により切換制御される後に詳述する電圧反転器９Ｃとが夫々介装された電源回路９Ｄと、を備えて構成される。
【００２３】
更に、電極端子８は、絶縁材料からなるハウジング１１に保持されている。
又、燃料供給管１２は鉄等の金属から構成されており、ボビン２内に挿入され、ハウジング１に固定されている。
ここで、前記電圧反転器９Ｃは、電磁コイル５に印加する電圧を正・逆に反転切換して、電磁コイルに駆動電流と該駆動電流と逆方向の電流を供給するものであり、４つのスイッチ片ａ〜ｄと、各スイッチ片ａ〜ｄにより切り換えられる一対ずつのスイッチ端子ａ_１，ａ_２、ｂ_１，ｂ_２、ｃ_１，ｃ_２、ｄ_１，ｄ_２、とから構成され、各スイッチ片ａ〜ｄを実線で示す状態に切り換えることにより、即ち、スイッチ片ａ〜ｄを夫々スイッチ端子ａ_２、ｂ_２、ｃ_１，ｄ_１側に切り換えることにより、電磁コイル５に電流が矢印Ａの如く流れ（正電圧印加；状態１）、スイッチ片ａ〜ｄを夫々スイッチ端子ａ_１、ｂ_１、ｃ_２、ｄ_２側に切り換えることにより、電磁コイル５に電流が矢印Ｂの如く前記とは反転して流れる（逆電圧印加；状態２）ように構成されている。
【００２４】
そして、前記制御回路９Ａは、燃料噴射弁の通常制御時には、状態１の如く電流を流すべく、電圧反転器９Ｃを正電圧印加側に切り換えると共に、図示しない内燃機関の運転状態検出手段としての回転速度センサや吸入空気量センサ等からの検出信号に基づいて、燃料噴射のタイミングを演算し、演算された噴射時期に噴射量に応じた時間だけ、燃料噴射弁の電磁コイルに駆動電流を供給する。
【００２５】
又、制御回路９Ａは、例えば、機関の始動を含む低温の運転条件並びに機関の所定回転速度未満かつ所定負荷未満の運転条件での、燃料の非噴射域で、状態２の如く電流を流すべく、電圧反転器９Ｃを逆電圧印加側に切り換える。
前記燃料の噴射域と非噴射域は、図３に示すようであり、燃料の噴射域である機関の吸気行程における図の領域Ａでは、正電圧を電磁コイル５に印加し、燃料の非噴射域である機関の膨張行程と排気行程における図の領域Ｂでは、逆電圧を電磁コイル５に印加する。
【００２６】
次に、図４のフローチャートに基づいて、上述の制御回路の制御の内容を詳細に説明する。
ステップ１において、イグニッションがＯＮとされた後、ステップ２〜４において、機関の始動を含む低温の運転条件並びに機関の所定回転速度未満かつ所定負荷未満の運転条件の判定を行う。
【００２７】
即ち、ステップ２にて、機関冷却水温が所定値Ｔ（例えば、５０°Ｃ）を越えたか否かが判定され、ステップ３にて、機関回転速度が所定値Ｎ（例えば、１０００ｒ．ｐ．ｍ）を越えたか否かが判定され、ステップ４にて、機関の負荷としての燃料噴射パルス幅Ｔｐが所定値Ａ（例えば、４ｍｓｅｃ）を越えたか否かが判定され、機関冷却水温＞Ｔ、機関回転速度＞Ｎ、Ｔｐ＞Ａが全て判定されると、制御を継続するべく、ステップ６以降に進み、機関冷却水温、機関回転速度、Ｔｐのいずれかが所定値以上であると判定されると、ステップ５に進んで、制御を中止する。
【００２８】
ステップ６では、燃料噴射量が計算され、ステップ７では、燃料噴射時期が計算され、ステップ８に進む。
ステップ８では、燃料噴射時期であるか否かが判定され、図３の領域Ｂであって、燃料噴射時期であれば、ステップ９にて、電圧反転器９Ｃを正電圧印加側に切り換えて、ステップ１０にて、燃料の噴射制御を実行する。
【００２９】
次のステップ１１では、燃料噴射終わりであるか否かが判定され、燃料噴射終わりと判定されるまで、ステップ１０で燃料の噴射制御が実行され、燃料噴射終わりと判定されると、ステップ２に戻る。
一方、ステップ８にて、図３の領域Ａであって、非燃料噴射時期であれば、ステップ１２にて、電圧反転器９Ｃを逆電圧印加側に切り換えて、ステップ１３にて、図１のパワートランジスタ９ＢをＯＮに切り換えて、電磁コイル５に逆電流を流し、ステップ２に戻る。
【００３０】
このように、非燃料噴射時期で、電磁コイル５に逆電流を流すことにより、電磁コイル５は発熱し、この電磁コイル５の発熱によって、電磁コイル５の中に配置されている燃料通路管１２が加熱される結果、燃料噴射時期で、即ち、図４のフローチャートのステップ１０における燃料噴射の実行時に、この燃料通路管１２中を通過する燃料が加熱される。
【００３１】
以上のように構成された実施形態によると、燃料噴射弁における電磁コイル５と、電圧反転器９Ｃを用いた簡単な構成により、所定の運転条件で燃料を加熱することができる。
このように加熱された燃料の噴霧は気化が促進され、かつその粒径が細かいため、吸入空気との混合性が向上し、均一混合気を機関に供給できるため、完全燃焼を行わせることができる。
【００３２】
この結果、始動性の向上、低温の運転条件並びに機関の所定回転速度未満かつ所定負荷未満の運転条件での燃焼安定性の向上を図ることができ、排気性能の向上、燃費の向上等を図ることができる。
ここで、機関の高回転・高負荷の運転条件では、燃料流量自体が多量であり、これらの運転条件では、燃料の加熱を行う割りに効果代が少なく、電磁コイル５用の電力消費量が浪費されるに過ぎず、かつ機関の燃焼温度そのものが高くなるため、燃料の気化促進・微粒化の必要性が少ない。
【００３３】
上記の実施形態においては、機関の所定回転速度未満かつ所定負荷未満の運転条件で、燃料を加熱するが、機関の高回転・高負荷の運転条件では、燃料の加熱を行わない制御を実行するため、無駄な燃料の加熱が行われず、電磁コイル５用の電力消費量の無駄な浪費が防止され、燃料を有効的に加熱することができると共に、不必要な電気負荷を機関に与えることなく、燃費性能の悪化を未然に防止することができる。
【００３４】
又、本構成によると、燃料噴射弁自体には、これの構成部材とは別の部材を付加する必要がないため、燃料噴射弁の構造の複雑化、大型化を来すことがなく、取付性にも支障を来すことがなく、コスト的にも有利である。
又、燃料と電磁コイル５の加熱によって加熱される燃料通路管１２との接触面積が大きいため、伝熱効率が良く、燃料の加熱性が高い。
【００３５】
更に、電磁コイル５の開弁動作には影響がない逆電流を流してこれを加熱するため、燃料噴射させずに燃料を有効に加熱する時間が、燃料の非噴射時期において、大きくとることが可能であり、十分な燃料加熱効果が得られる。
尚、本実施形態では、機関の始動を含む低温の運転条件並びに機関の所定回転速度未満かつ所定負荷未満の運転条件にて電磁コイル５に逆電流を流す構成として、始動性及び燃焼安定性の向上を図るようにしたが、燃料の気化性に劣るその他の所定運転条件で電磁コイルに逆電流を流す構成としても良い。
【図面の簡単な説明】
【図１】本発明の内燃機関の燃料噴射装置における燃料噴射弁の駆動回路を示す図
【図２】同上の燃料噴射装置における燃料噴射弁の断面図
【図３】機関作動行程に対する燃料噴射弁の燃料噴射域と非燃料噴射域とを説明するタイムチャート
【図４】同上の駆動回路における制御回路の制御内容を説明するフローチャート
【符号の説明】
５電磁コイル
９駆動回路
９Ａ制御回路
９Ｂパワートランジスタ
９Ｃ電圧反転器
９Ｄ電源回路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device having a function of heating fuel with a fuel injection valve in order to improve fuel vaporization.
[0002]
[Prior art]
2. Description of the Related Art Electronically controlled fuel injection devices provided with a fuel injection valve for each cylinder of an internal combustion engine are widely used.For example, low-temperature operating conditions including start-up and operation at a speed lower than a predetermined rotation speed and lower than a predetermined load of the engine. Under the conditions, the fuel injected from the fuel injection valve is not sufficiently vaporized, so that the mixing property between the fuel and air is poor, the startability is deteriorated, the combustion stability is deteriorated, and the exhaust performance and fuel efficiency are deteriorated. Problem.
[0003]
For this reason, conventionally, various technologies for heating fuel to improve vaporization have been proposed.
For example, in JP-A-63-170555, a heater is provided on a member having an injection hole in a fuel injection valve, and the member is heated by a heater, so that fuel and an injection hole passing through the injection hole are provided. A technology for heating fuel in a fuel injection valve immediately before the fuel injection valve is disclosed.
[0004]
Japanese Patent Application Laid-Open No. 7-83091 discloses that in order to improve the startability of an internal combustion engine in cold weather, an opening signal that is short enough not to open the fuel injection valve is given to the fuel injection valve to heat the fuel injection valve. Thus, a technique for removing icing from a valve core, a valve seat, and the like is disclosed.
Further, Japanese Patent Application Laid-Open No. Hei 5-39883 discloses that a high-frequency current is applied to an electromagnetic coil of a fuel injection valve, and a member provided inside the electromagnetic coil is heated by magnetic induction to heat the fuel injection valve. Techniques for heating fuel are disclosed.
[0005]
[Problems to be solved by the invention]
However, each of the above techniques has the following problems.
That is, in the technique disclosed in Japanese Patent Application Laid-Open No. 63-170555, a heater is provided on a member having an injection hole in a fuel injection valve. Since this is a configuration in which another member is added, the structure of the fuel injection valve becomes complicated, the size of the fuel injection valve becomes large, and the mountability is hindered.
[0006]
Further, the contact surface between the fuel and the member heated by the heater cannot be said to be large, the heat transfer efficiency is poor, and the heating property of the fuel is low.
In the technology disclosed in Japanese Patent Application Laid-Open No. 7-83091, the opening time of the fuel injection valve is a short time (for example, about 5 ms) that does not inject fuel, so that only fuel is effectively heated without fuel injection. Time is not enough to obtain a sufficient effect.
[0007]
In the technique disclosed in Japanese Patent Application Laid-Open No. 5-39883, it is necessary to provide a high-frequency power supply for supplying a high-frequency current to the electromagnetic coil of the fuel injection valve.
In view of the above problems, the present invention is directed to a fuel injection device having a function of heating fuel with a fuel injection valve in order to improve fuel vaporization, and the structure of the fuel injection valve itself. It is an object of the present invention to provide a fuel injection device for an internal combustion engine that can obtain a sufficient fuel heating effect with a simple configuration that does not cause inconveniences such as complexity, increase in size, and high cost.
[0008]
[Means for Solving the Problems]
Therefore, the invention according to claim 1 is
A fuel injection valve including a valve element that opens and closes a fuel passage, a movable iron core that drives the valve element, and an electromagnetic coil, and a drive that includes an intermittent unit that intermittently drives electric current to the electromagnetic coil. A fuel injection device of an internal combustion engine configured to include a circuit and to drive the valve body by opening the valve element by attracting a movable iron core by an electromagnetic force generated by supplying a drive current to the electromagnetic coil.
The drive circuit, provided with a reverse current supply means for supplying a current in a direction opposite to the drive current to the electromagnetic coil,
The reverse current supply means, Oite in one cycle, with strokes other than stroke of the engine the injection region of the fuel is set, and supplying the reverse current.
[0009]
The invention according to claim 2 is
Means for determining a predetermined operating state of the engine;
Means for determining the fuel injection timing and a non-injection timing in a non -injection region of the fuel set in a region other than the injection region ,
A drive circuit is provided in the drive circuit and supplies a current in a direction opposite to the drive current to the electromagnetic coil when the engine is in a predetermined operation state and at a non-fuel injection timing based on the determination results from both determination means. A control circuit for controlling the intermittent means and the reverse current supply means to supply the electromagnetic coil with a drive current when the engine is in a predetermined operating state and at a fuel injection timing;
Is characterized by comprising.
[0010]
The invention according to claim 3 is:
The predetermined operating state of the engine is a low-temperature operating condition including starting of the engine.
The invention according to claim 4 is
The predetermined operating state of the engine is an operating condition that is lower than a predetermined rotation speed of the engine and lower than a predetermined load.
[0011]
The invention according to claim 5 is
The reverse current supply means comprises a voltage inverter for switching the voltage applied to the electromagnetic coil between forward and reverse to supply a drive current to the electromagnetic coil and a current in a direction opposite to the drive current. .
The operation of the present invention will be described.
[0012]
In the invention according to claim 1, with a simple configuration using an electromagnetic coil for driving a valve body in a fuel injection valve, and a reverse current supply unit that supplies a current in a direction opposite to the drive current to the electromagnetic coil, The fuel is heated. The reverse current supply means supplies the current in the reverse direction in a cycle other than the stroke of the engine in which the fuel injection region is set in one cycle.
The fuel spray thus heated is promoted to vaporize and has a small particle size, so that the mixing property between the fuel and the intake air is improved, and a uniform air-fuel mixture can be supplied to the engine, so that complete combustion is performed. be able to.
[0013]
As a result, it is possible to improve low-temperature startability and the like, and to improve exhaust performance, fuel efficiency, and the like.
In the invention according to claim 2, when the engine is in the predetermined operating state and the fuel is not being injected, a current in a direction opposite to the driving current is supplied to the electromagnetic coil to heat the fuel.
[0014]
In this case, since a reverse current that does not affect the valve opening operation of the electromagnetic coil flows and is heated, the time for effectively heating the fuel without injecting the fuel may be large at the non-injection timing of the fuel. It is possible and a sufficient fuel heating effect can be obtained.
In the invention according to claim 3, the fuel is heated under low-temperature operating conditions including starting of the engine, and under these operating conditions, the fuel injected from the fuel injection valve is sufficiently vaporized, and the mixing property between the fuel and the air is reduced. As a result, the startability and combustion stability of the engine are improved.
[0015]
Here, under the operating conditions of high engine speed and high load of the engine, the fuel flow rate itself is large, and under these operating conditions, the effect cost is small for heating the fuel, and the power consumption for the electromagnetic coil is wasted. And the combustion temperature of the engine itself becomes high, so that it is less necessary to promote the vaporization and atomization of the fuel.
Therefore, in the invention according to claim 4, the fuel is heated under operating conditions of less than the predetermined rotational speed and less than the predetermined load of the engine, and under these operating conditions, the fuel injected from the fuel injection valve is sufficiently vaporized, Improving the mixability of fuel and air, improving the combustion stability of the engine, and stopping the heating of the fuel under high-rotation, high-load operating conditions of the engine, the power consumption for the electromagnetic coil Waste can be prevented, fuel can be effectively heated, and deterioration of fuel efficiency can be prevented.
[0016]
In the invention according to claim 5, the electromagnetic coil is easily switched between the normal fuel injection control state and the fuel heating control state by the voltage inverter.
[0017]
【The invention's effect】
According to the first aspect of the present invention, it is possible to improve the fuel vaporization, improve the exhaust performance, improve the fuel efficiency, and the like. Since it is not necessary to add another member, the structure and the size of the fuel injection valve are not complicated, the mounting is not hindered, and the cost is advantageous. Further, since the contact area between the portion to be heated by the heating of the fuel and the electromagnetic coil is large, good heat transfer efficiency, heating of the fuel is not high. Furthermore, in order to heat it in the valve opening operation of the electromagnetic coil by flowing reverse current is not affected, the time to effectively heat the fuel without the fuel injection is possible large Kikutoru, sufficient fuel heating The effect is obtained.
[0018]
According to the second aspect of the invention, the time for effectively heating the fuel can be increased at the non-injection timing of the fuel, and a sufficient fuel heating effect can be obtained in the predetermined operation state.
According to the third aspect of the invention, it is possible to improve the startability and combustion stability of the engine under low-temperature operating conditions including the start of the engine.
[0019]
According to the fourth aspect of the invention, the combustion stability can be improved under the operating condition of the engine lower than the predetermined rotational speed and lower than the predetermined load. Is stopped, wasteful waste of power consumption for the electromagnetic coil is prevented, and fuel can be heated effectively.
According to the fifth aspect of the present invention, by applying the voltage inverter, the electromagnetic coil can be easily switched between the normal fuel injection control state and the fuel heating control state. A fuel injection device having a function can be provided.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
First, a configuration of an embodiment of a fuel injection valve according to the present invention will be described with reference to FIG.
In this figure, a bobbin 2 made of a non-magnetic material is inserted into a valve housing 1 made of a magnetic material, and an electromagnetic coil 5 is wound around the bobbin 2.
[0021]
A movable iron core 3 is inserted into the valve housing 1, and a needle 4 as a valve body is coupled to the movable iron core 3.
Further, a nozzle body 7 is provided at a distal end portion of the valve housing 1 via a spacer 7a. The needle 4 penetrates through the spacer 7a and is supported on the inner peripheral surface of the nozzle body 7. Of the nozzle body 7 closes an injection hole 7b formed at the tip of the nozzle body 7.
[0022]
The electromagnetic coil 5 is connected to an electrode terminal 8 and is connected to a drive circuit 9 of the fuel injection valve by a lead wire 10.
Then, as shown in FIG. 1, the drive circuit 9 is controlled by a control circuit 9A, a power transistor 9B as an intermittent means that is turned on / off by a control signal from the control circuit 9A, and a control signal from the control circuit 9A. And a power supply circuit 9D in which a voltage inverter 9C described in detail after the switching control is provided.
[0023]
Further, the electrode terminals 8 are held in a housing 11 made of an insulating material.
The fuel supply pipe 12 is made of a metal such as iron, is inserted into the bobbin 2, and is fixed to the housing 1.
Here, the voltage inverter 9C reverses the voltage applied to the electromagnetic coil 5 between forward and reverse to supply a drive current and a current in the opposite direction to the drive current to the electromagnetic coil. It is composed of switch pieces a to d, and a pair of switch terminals a ₁ , a ₂ , b ₁ , b ₂ , c ₁ , c ₂ , d ₁ , d ₂ each of which is switched by each of the switch pieces a to d. By switching the switch pieces a to d to the state shown by the solid line, that is, by switching the switch pieces a to d to the switch terminals a ₂ , b ₂ , c ₁ , and d ₁ , respectively, a current flows through the electromagnetic coil 5. The current flows through the electromagnetic coil 5 as shown by the arrow B by flowing as shown by the arrow A (positive voltage application; state 1) and switching the switch pieces a to d to the switch terminals a ₁ , b ₁ , c ₂ , and d ₂ , respectively. It flows in reverse to the above. It applied; state 2) is configured as.
[0024]
During the normal control of the fuel injection valve, the control circuit 9A switches the voltage inverter 9C to the positive voltage application side so that the current flows as in state 1, and also controls the rotation as the operating state detecting means (not shown) of the internal combustion engine. The fuel injection timing is calculated based on detection signals from a speed sensor, an intake air amount sensor, and the like, and a drive current is supplied to the electromagnetic coil of the fuel injection valve for a time corresponding to the injection amount at the calculated injection timing. .
[0025]
Further, the control circuit 9A is configured to supply a current as in state 2 in a non-injection region of fuel under low-temperature operating conditions including starting of the engine and operating conditions of less than a predetermined rotational speed and less than a predetermined load of the engine. Then, the voltage inverter 9C is switched to the reverse voltage application side.
The fuel injection region and the non-injection region are as shown in FIG. 3. In a region A in the intake stroke of the engine, which is a fuel injection region, a positive voltage is applied to the electromagnetic coil 5 to prevent the fuel from being injected. In the region B in the drawing in the engine expansion stroke and exhaust stroke, which is a region, a reverse voltage is applied to the electromagnetic coil 5.
[0026]
Next, the contents of the control of the above-described control circuit will be described in detail based on the flowchart of FIG.
After the ignition is turned on in Step 1, in Steps 2 to 4, low-temperature operating conditions including starting of the engine and operating conditions of less than a predetermined rotational speed and less than a predetermined load of the engine are determined.
[0027]
That is, in step 2, it is determined whether or not the engine cooling water temperature has exceeded a predetermined value T (for example, 50 ° C.). In step 3, the engine speed is set to a predetermined value N (for example, 1000 rpm). ) Is determined, and in step 4, it is determined whether the fuel injection pulse width Tp as a load of the engine has exceeded a predetermined value A (for example, 4 msec). When it is determined that the rotation speed> N and Tp> A are all determined, the process proceeds to step 6 and subsequent steps in order to continue the control. , And the control is stopped.
[0028]
In step 6, the fuel injection amount is calculated, and in step 7, the fuel injection timing is calculated, and the routine proceeds to step 8.
In step 8, it is determined whether or not it is the fuel injection timing. If it is the region B in FIG. 3 and it is the fuel injection timing, in step 9, the voltage inverter 9C is switched to the positive voltage application side, In step 10, fuel injection control is executed.
[0029]
In the next step 11, it is determined whether or not the fuel injection has been completed. Until it is determined that the fuel injection has been completed, the fuel injection control is executed in step 10. If it is determined that the fuel injection has been completed, the process proceeds to step 2. Return.
On the other hand, if it is the non-fuel injection timing in the area A of FIG. 3 at step 8, the voltage inverter 9C is switched to the reverse voltage application side at step 12, and at step 13, The power transistor 9B is turned on, a reverse current flows through the electromagnetic coil 5, and the process returns to step 2.
[0030]
As described above, when the reverse current flows through the electromagnetic coil 5 at the non-fuel injection timing, the electromagnetic coil 5 generates heat, and the heat generated by the electromagnetic coil 5 causes the fuel passage tube 12 arranged in the electromagnetic coil 5 to generate heat. As a result, the fuel passing through the fuel passage tube 12 is heated at the fuel injection timing, that is, at the time of executing the fuel injection in Step 10 of the flowchart of FIG.
[0031]
According to the embodiment configured as described above, the fuel can be heated under predetermined operating conditions with a simple configuration using the electromagnetic coil 5 in the fuel injection valve and the voltage inverter 9C.
The fuel spray thus heated is promoted to vaporize and has a small particle size, so that the mixture with the intake air is improved and a uniform mixture can be supplied to the engine, so that complete combustion can be performed. it can.
[0032]
As a result, it is possible to improve the startability, improve the combustion stability under low-temperature operation conditions and under the operation conditions in which the engine speed is lower than a predetermined rotation speed and lower than a predetermined load, and improve exhaust performance, fuel efficiency, and the like. be able to.
Here, under high engine speed and high load operating conditions, the fuel flow rate itself is large. Under these operating conditions, the effect cost is small for heating the fuel, and the power consumption for the electromagnetic coil 5 is low. Since it is simply wasted and the combustion temperature of the engine itself becomes high, there is little need to promote vaporization and atomization of the fuel.
[0033]
In the above-described embodiment, the fuel is heated under the operating condition of less than the predetermined rotational speed and less than the predetermined load of the engine, but the control that does not heat the fuel is performed under the operating condition of the high rotation speed and the high load of the engine. Therefore, wasteful heating of the fuel is not performed, wasteful consumption of electric power for the electromagnetic coil 5 is prevented, fuel can be heated effectively, and unnecessary electric load is not applied to the engine. In addition, it is possible to prevent fuel economy performance from deteriorating.
[0034]
Further, according to the present configuration, it is not necessary to add another member to the fuel injection valve itself, so that the structure of the fuel injection valve does not become complicated and large, and the fuel injection valve can be mounted. It does not hinder the performance and is advantageous in terms of cost.
Further, since the contact area between the fuel and the fuel passage tube 12 heated by the heating of the electromagnetic coil 5 is large, the heat transfer efficiency is high and the fuel heating property is high.
[0035]
Further, since a reverse current which does not affect the valve opening operation of the electromagnetic coil 5 is supplied and heated, the time for effectively heating the fuel without injecting the fuel can be increased at the non-injection timing of the fuel. It is possible and a sufficient fuel heating effect can be obtained.
In the present embodiment, a reverse current is applied to the electromagnetic coil 5 under low-temperature operating conditions including starting of the engine and operating conditions lower than a predetermined rotation speed of the engine and lower than a predetermined load, so that startability and combustion stability are improved. Although an improvement has been made, a configuration may be adopted in which a reverse current flows through the electromagnetic coil under other predetermined operating conditions in which fuel vaporization is inferior.
[Brief description of the drawings]
FIG. 1 is a diagram showing a drive circuit of a fuel injection valve in a fuel injection device for an internal combustion engine according to the present invention; FIG. 2 is a cross-sectional view of the fuel injection valve in the fuel injection device; FIG. 4 is a time chart for explaining a fuel injection region and a non-fuel injection region of FIG. 4. FIG. 4 is a flowchart for explaining control contents of a control circuit in a drive circuit of the above.
5 Electromagnetic coil 9 Drive circuit 9A Control circuit 9B Power transistor 9C Voltage inverter 9D Power supply circuit

Claims

A fuel injection valve including a valve element that opens and closes a fuel passage, a movable iron core that drives the valve element, and an electromagnetic coil, and a drive that includes an intermittent unit that intermittently drives electric current to the electromagnetic coil. A fuel injection device of an internal combustion engine configured to include a circuit and to drive the valve body by opening the valve element by attracting a movable iron core by an electromagnetic force generated by supplying a drive current to the electromagnetic coil.
The drive circuit, provided with a reverse current supply means for supplying a current in a direction opposite to the drive current to the electromagnetic coil,
The reverse current supply means in one cycle, with strokes other than stroke of the engine the injection region of the fuel is set, the fuel injection system for an internal combustion engine and supplying the reverse current.

Means for determining a predetermined operating state of the engine;
Means for determining the fuel injection timing and a non-injection timing in a non -injection region of the fuel set in a region other than the injection region ,
A drive circuit is provided in the drive circuit and supplies a current in a direction opposite to the drive current to the electromagnetic coil when the engine is in a predetermined operation state and at a non-fuel injection timing based on the determination results from both determination means. A control circuit for controlling the intermittent means and the reverse current supply means to supply the electromagnetic coil with a drive current when the engine is in a predetermined operating state and at a fuel injection timing;
The fuel injection device for an internal combustion engine according to claim 1, wherein the fuel injection device is configured to include:

3. The fuel injection device for an internal combustion engine according to claim 2, wherein the predetermined operating state of the engine is a low-temperature operating condition including starting of the engine.

4. The fuel injection device for an internal combustion engine according to claim 2, wherein the predetermined operation state of the engine is an operation condition under a predetermined rotation speed and a predetermined load of the engine.

The reverse current supply means includes a voltage inverter for switching the voltage applied to the electromagnetic coil between forward and reverse to supply a drive current to the electromagnetic coil and a current in a direction opposite to the drive current. A fuel injection device for an internal combustion engine according to any one of claims 1 to 4.