JPH08296520A - Accumulator fuel injection device - Google Patents
Accumulator fuel injection deviceInfo
- Publication number
- JPH08296520A JPH08296520A JP10604895A JP10604895A JPH08296520A JP H08296520 A JPH08296520 A JP H08296520A JP 10604895 A JP10604895 A JP 10604895A JP 10604895 A JP10604895 A JP 10604895A JP H08296520 A JPH08296520 A JP H08296520A
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- Prior art keywords
- chamber
- pressure
- injection
- fuel
- passage
- Prior art date
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Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、蓄圧室内に貯蔵された
高圧の燃料をディーゼルエンジン等に噴射供給する蓄圧
式燃料噴射装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-accumulation type fuel injection device for injecting high-pressure fuel stored in a pressure accumulation chamber to a diesel engine or the like.
【0002】[0002]
【従来の技術】蓄圧式燃料噴射装置のシステム全体を図
7に示す。図示するように、燃料タンクa内の燃料は、
高圧ポンプbによって汲み上げられ、コモンレールと呼
ばれる蓄圧室cに圧送されて高圧状態で貯蔵される。こ
の蓄圧室c内の圧力は、圧力センサdによりフィードバ
ックされ、高圧ポンプbの送油量をコントロールするこ
とによって、一定に保たれるようになっている。2. Description of the Related Art FIG. 7 shows the entire system of a pressure accumulating fuel injection device. As shown in the figure, the fuel in the fuel tank a is
It is pumped up by the high-pressure pump b, is pressure-fed to a pressure accumulating chamber c called a common rail, and is stored in a high-pressure state. The pressure in the accumulator c is fed back by the pressure sensor d, and is kept constant by controlling the amount of oil fed by the high-pressure pump b.
【0003】蓄圧室c内の高圧の燃料は、供給系fを通
ってインジェクタgに導かれ、その内部に設けられた電
磁弁(後述する三方弁q)の開閉により、ノズル先端部
の噴射口hからディーゼルエンジン等の燃焼室内に噴射
される。このインジェクタgには、余分な燃料を燃料タ
ンクaに戻す回収系iが接続されている。また、上記高
圧ポンプb、蓄圧室cおよびインジェクタgは、コント
ロールユニットjによって適宜制御されるようになって
いる。The high-pressure fuel in the accumulator c is guided to an injector g through a supply system f, and an electromagnetic valve (a three-way valve q described later) provided inside the injector g is opened and closed to inject an injection port at the tip of the nozzle. It is injected from h into the combustion chamber of a diesel engine or the like. A recovery system i for returning excess fuel to the fuel tank a is connected to the injector g. Further, the high pressure pump b, the pressure accumulating chamber c, and the injector g are appropriately controlled by the control unit j.
【0004】インジェクタgの概要を図8に示す。図示
するように、蓄圧室c内に貯蔵された高圧の燃料は、上
記供給系fから分岐された噴射通路kを介して針弁l先
端側の噴射室mに導かれると共に、制御通路nを介して
針弁l根元側の制御室oに導かれる。制御室o内の燃料
は、リーク通路pを介して回収系iに戻される。リーク
通路pと制御通路nと制御室oとの接合部には、三方弁
q(電磁弁)が設けられている。三方弁qは、制御通路
nと制御室oとを連通するフィード状態と、制御室oと
リーク通路pとを連通するリーク状態とを切り替える。An outline of the injector g is shown in FIG. As shown in the figure, the high-pressure fuel stored in the pressure accumulating chamber c is guided to the injection chamber m on the tip end side of the needle valve 1 through the injection passage k branched from the supply system f, and also through the control passage n. It is guided to the control chamber o on the base side of the needle valve 1 via the. The fuel in the control chamber o is returned to the recovery system i via the leak passage p. A three-way valve q (solenoid valve) is provided at the junction of the leak passage p, the control passage n, and the control chamber o. The three-way valve q switches between a feed state in which the control passage n communicates with the control chamber o and a leak state in which the control chamber o communicates with the leak passage p.
【0005】上記構成によれば、噴射室m内の燃圧は針
弁lのコーン部rに作用してそれを上昇(開弁)させる
ように働き、制御室o内の燃圧は針弁lを下降(閉弁)
させるように働く。よって、これらの燃圧がバランスし
ている状態から三方弁qをリーク状態とすると、圧力バ
ランスが崩れて針弁lが上昇し、噴射室m内の燃料がノ
ズル先端部の噴射口hから噴射される。その後、三方弁
qをフィード状態に切り替えると、再び上下の圧力がバ
ランスし、針弁lが下降して噴射口hを塞ぎ、噴射が終
了する。According to the above construction, the fuel pressure in the injection chamber m acts on the cone portion r of the needle valve l to raise (open) it, and the fuel pressure in the control chamber o causes the needle valve l to rise. Down (valve closed)
Work to let. Therefore, if the three-way valve q is made to leak from the state where these fuel pressures are balanced, the pressure balance is broken and the needle valve 1 rises, and the fuel in the injection chamber m is injected from the injection port h at the tip of the nozzle. It After that, when the three-way valve q is switched to the feed state, the upper and lower pressures are balanced again, the needle valve 1 descends to close the injection port h, and the injection ends.
【0006】[0006]
【発明が解決しようとする課題】上述のシステムにおい
ては、実質的な噴射燃料を蓄積する噴射室mと、針弁l
の昇降(開閉)を制御する制御室oとが、一つの蓄圧室
cから供給系fおよび通路k,nを介して分岐して接続
されている。このため、噴射圧を高めるべく蓄圧室cの
圧力を高くすると、噴射室mの圧力のみならず制御室o
の圧力をも高くなってしまう。In the system described above, the injection chamber m for accumulating substantially injected fuel and the needle valve 1 are provided.
Is connected to a control chamber o for controlling the raising and lowering (opening and closing) of the same from one pressure accumulating chamber c via a supply system f and passages k and n. Therefore, if the pressure of the pressure accumulating chamber c is increased to increase the injection pressure, not only the pressure of the injection chamber m but also the control chamber o
It will also increase the pressure.
【0007】この結果、三方弁qによって制御室oから
リーク通路p(回収系i)へ逃がされるリーク燃料量が
多くなり、その分だけ高圧ポンプbの無駄仕事が増大
し、車両の燃費が悪化する。As a result, the amount of leak fuel escaped from the control chamber o to the leak passage p (recovery system i) by the three-way valve q increases, and the wasteful work of the high-pressure pump b increases correspondingly, which deteriorates the fuel efficiency of the vehicle. To do.
【0008】また、三方弁qには、圧力が高くなるとそ
の構造上、側圧が発生してしまうため、圧力が高くなる
と作動力を増大させなくてはならなくなり、三方弁q
(電磁弁)の消費電流も増大する。Further, since the side pressure is generated in the three-way valve q due to its structure when the pressure becomes higher, the operating force must be increased when the pressure becomes higher, and the three-way valve q
The current consumption of the (solenoid valve) also increases.
【0009】また、このように制御室oの圧力が高まる
と、三方弁qの内部にコジリや変形等が生じる虞がある
ため、その耐久性・信頼性が低下する。また、コジリ等
に起因して三方弁qの作動がしぶくなるため、三方弁q
の作動応答性が悪化する。Further, if the pressure in the control chamber o is increased in this way, the inside of the three-way valve q may be twisted or deformed, so that its durability and reliability are deteriorated. In addition, since the operation of the three-way valve q becomes slow due to kinking etc., the three-way valve q
Operation response is deteriorated.
【0010】また、針弁lの開閉に応じて噴射室m内の
圧力が変動するが、その変動の影響が通路kおよび通路
nを介して三方弁qに伝わり、三方弁qがダメージを受
けることも考えられる。Further, the pressure in the injection chamber m fluctuates according to the opening / closing of the needle valve 1, but the influence of the fluctuation is transmitted to the three-way valve q via the passages k and n, and the three-way valve q is damaged. It is also possible.
【0011】以上の事情を考慮して創案された本発明の
目的は、噴射圧の高圧化とリーク燃料量の低減とを両立
できる蓄圧式燃料噴射装置を提供することにある。An object of the present invention, which was devised in view of the above circumstances, is to provide a pressure accumulating fuel injection device capable of both increasing the injection pressure and reducing the amount of leaked fuel.
【0012】なお、関連する技術として特開平6-108948
号公報等が知られている。As a related technique, Japanese Patent Laid-Open No. 6-108948
Publications and the like are known.
【0013】[0013]
【課題を解決するための手段】上記目的を達成するため
に本発明は、蓄圧室内に貯蔵された燃料を針弁先端側の
噴射室と針弁根元側の制御室とに導き、その制御室内の
燃料を回収系に逃がすことにより針弁をリフトさせ、噴
射室内の燃料を噴射する蓄圧式燃料噴射装置において、
上記蓄圧室を高圧室と低圧室とに分割し、その高圧室と
上記噴射室とを接続する噴射通路を設けると共に、低圧
室と上記制御室とを接続する制御通路を設けて構成され
ている‥‥。In order to achieve the above object, the present invention guides fuel stored in a pressure accumulating chamber to an injection chamber on the needle valve tip side and a control chamber on the needle valve base side, and the control chamber In the pressure-accumulation fuel injection device that lifts the needle valve by letting the fuel in the recovery system escape and injects the fuel in the injection chamber,
The pressure accumulating chamber is divided into a high pressure chamber and a low pressure chamber, an injection passage connecting the high pressure chamber and the injection chamber is provided, and a control passage connecting the low pressure chamber and the control chamber is provided. .....
【0014】上記噴射通路と制御通路とを接続するバイ
パス通路を設け、そのバイパス通路の接続部より上流側
の噴射通路に第1開閉弁を設け、上記制御室内の燃料を
回収系へ逃がすリーク通路に第2開閉弁を設けてもよい
‥‥。A bypass passage for connecting the injection passage and the control passage is provided, and a first opening / closing valve is provided in the injection passage upstream of the connection portion of the bypass passage to leak the fuel in the control chamber to the recovery system. A second on-off valve may be provided in.
【0015】上記第1開閉弁より下流側でバイパス通路
の接続部より上流側の噴射通路に、絞り部を設けてもよ
い‥‥。A throttle portion may be provided in the injection passage downstream of the first opening / closing valve and upstream of the connection portion of the bypass passage.
【0016】[0016]
【作用】の構成によれば、高圧室内の高圧の燃料は、
噴射通路を通って針弁先端側の噴射室に導入され、針弁
のリフト時に高圧状態で噴射される。他方、低圧室内の
低圧の燃料は、制御通路を通って針弁根元側の制御室に
導入され、針弁の作動流体として用いられた後、低圧状
態で回収系に逃がされる。このように、高圧室内の高圧
の燃料を噴射燃料として用い、低圧室内の低圧の燃料を
針弁の作動流体として用いているので、燃料噴射圧が高
まり、同時にリーク燃料量が低減する。According to the constitution of the function, the high pressure fuel in the high pressure chamber is
It is introduced into the injection chamber on the needle valve tip side through the injection passage, and is injected in a high pressure state when the needle valve is lifted. On the other hand, the low-pressure fuel in the low-pressure chamber is introduced into the control chamber on the base side of the needle valve through the control passage, used as the working fluid for the needle valve, and then released to the recovery system in a low pressure state. As described above, since the high-pressure fuel in the high-pressure chamber is used as the injection fuel and the low-pressure fuel in the low-pressure chamber is used as the working fluid for the needle valve, the fuel injection pressure is increased and the leaked fuel amount is reduced at the same time.
【0017】の構成によれば、最初、噴射通路の第1
開閉弁と、リーク通路の第2開閉弁とを共に閉じてお
き、その後、第2開閉弁のみを開く。すると、制御室内
の燃料がリーク通路を通って回収系へ逃がされ、針弁が
リフトして噴射室内の燃料が噴射される。このとき、噴
射室内には、低圧室の低圧の燃料がバイパス通路を通っ
て供給されているため、低圧燃料噴射となる。その後、
第1開閉弁を開くと、高圧室の高圧の燃料が噴射通路を
通って噴射室に供給されるため、高圧燃料噴射となる。
これにより、燃焼初期における予混合燃焼が抑えられ、
急激な燃焼温度の上昇が抑制され、NOxが低減する。According to the construction of (1), the first of the injection passages is first provided.
Both the on-off valve and the second on-off valve in the leak passage are closed, and then only the second on-off valve is opened. Then, the fuel in the control chamber is released to the recovery system through the leak passage, the needle valve is lifted, and the fuel in the injection chamber is injected. At this time, since the low-pressure fuel in the low-pressure chamber is supplied to the injection chamber through the bypass passage, low-pressure fuel injection is performed. afterwards,
When the first on-off valve is opened, high-pressure fuel in the high-pressure chamber is supplied to the injection chamber through the injection passage, so high-pressure fuel injection is performed.
This suppresses premixed combustion in the early stages of combustion,
A rapid increase in combustion temperature is suppressed, and NOx is reduced.
【0018】の構成によれば、上記高圧燃料噴射の際
に、噴射通路を流れる燃料が絞り部によって絞られるの
で、高圧燃料噴射時の噴射立上り特性がなだらかにな
る。これにより、予混合燃焼時の急激な燃焼温度の上昇
が抑制され、NOxがさらに低減する。According to the above construction, since the fuel flowing through the injection passage is throttled by the throttle portion during the high-pressure fuel injection, the injection rising characteristic at the time of high-pressure fuel injection becomes gentle. As a result, a rapid increase in combustion temperature during premixed combustion is suppressed, and NOx is further reduced.
【0019】[0019]
【実施例】以下、本発明の一実施例を添付図面に基づい
て説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.
【0020】図1は、本実施例に係る蓄圧式燃料噴射装
置のシステム全体を示す図である。図示するように、こ
の蓄圧式燃料噴射装置は、燃料タンク1内の燃料を加圧
して圧送する高圧ポンプ2と、高圧ポンプ2に接続され
燃料を高圧( 1200bar程度)で貯蔵する高圧室3と、高
圧室3に接続され燃料を低圧(600bar程度)で貯蔵する
低圧室4と、高圧室3内の燃料を噴射燃料として用いる
と共に低圧室4内の燃料を針弁5の作動流体として用い
るインジェクタ6とから主に構成されている。FIG. 1 is a diagram showing the entire system of a pressure accumulation type fuel injection device according to this embodiment. As shown in the figure, this pressure-accumulation fuel injection device includes a high-pressure pump 2 that pressurizes and pumps the fuel in a fuel tank 1, and a high-pressure chamber 3 that is connected to the high-pressure pump 2 and stores the fuel at high pressure (about 1200 bar). A low pressure chamber 4 which is connected to the high pressure chamber 3 and stores the fuel at a low pressure (about 600 bar), and an injector which uses the fuel in the high pressure chamber 3 as an injection fuel and uses the fuel in the low pressure chamber 4 as a working fluid for the needle valve 5. It is mainly composed of 6 and 6.
【0021】高圧ポンプ2は、エンジンのクランク軸等
に連動されたカム軸7を回転させることによってプラン
ジャ8をバネ9に抗して往復動させ、燃料タンク1から
吸上ポンプ10によって吸上げられた燃料をシリンダ1
1内で加圧して高圧室3に圧送するものである。高圧ポ
ンプ2の流入通路12と排出通路13とは、返流通路1
4によってバイパスされている。返流通路14には、開
閉弁15が設けられている。また、排出通路13には、
逆止弁16が設けられている。The high pressure pump 2 reciprocates the plunger 8 against the spring 9 by rotating the cam shaft 7 which is interlocked with the crank shaft of the engine, and is sucked up from the fuel tank 1 by the suction pump 10. Cylinder fuel
It is pressurized in 1 and sent to the high-pressure chamber 3 by pressure. The inflow passage 12 and the discharge passage 13 of the high-pressure pump 2 are the return passage 1
Bypassed by 4. An opening / closing valve 15 is provided in the return passage 14. In addition, in the discharge passage 13,
A check valve 16 is provided.
【0022】高圧室3は、高圧ポンプ2の排出通路13
から圧送されてきた燃料を高圧状態( 1200bar程度)で
貯蔵するものである。また、高圧室3には、インジェク
タ6の噴射通路17と、低圧室4への連結通路18とが
接続されている。よって、高圧室3内の燃料は、その一
部が連結通路18を通って低圧室4に導かれ、残りが噴
射通路17を通ってインジェクタ6の針弁5先端側の噴
射室19に導かれる。噴射室19内に導かれた燃料は、
実質的な噴射燃料として用いられ、針弁5のリフトによ
って噴射口20から噴射される。また、高圧室3には、
圧力センサ21aが設けられている。The high pressure chamber 3 has a discharge passage 13 of the high pressure pump 2.
The fuel sent from the company is stored under high pressure (about 1200 bar). Further, an injection passage 17 of the injector 6 and a connection passage 18 to the low pressure chamber 4 are connected to the high pressure chamber 3. Therefore, a part of the fuel in the high pressure chamber 3 is guided to the low pressure chamber 4 through the connection passage 18, and the rest is guided to the injection chamber 19 on the tip side of the needle valve 5 of the injector 6 through the injection passage 17. . The fuel introduced into the injection chamber 19 is
It is used as substantially injected fuel and is injected from the injection port 20 by the lift of the needle valve 5. Also, in the high pressure chamber 3,
A pressure sensor 21a is provided.
【0023】低圧室4は、連結通路18を介して高圧室
3から導かれた燃料を低圧状態(600bar程度)で貯蔵す
るものである。低圧室4には、インジェクタ6の制御通
路21が接続されている。この制御通路21を通って低
圧室4から流出した燃料は、インジェクタ6の針弁5根
元側の制御室22に導かれ、針弁5の作動流体として用
いられ、最終的にはリーク通路23を介して回収系24
に逃がされる。また、低圧室4には、圧力センサ25が
設けられ、連結通路18には開閉弁26(電磁弁)が設
けられている。The low-pressure chamber 4 stores the fuel introduced from the high-pressure chamber 3 via the connecting passage 18 in a low-pressure state (about 600 bar). The control passage 21 of the injector 6 is connected to the low pressure chamber 4. The fuel flowing out of the low pressure chamber 4 through the control passage 21 is guided to the control chamber 22 on the base side of the needle valve 5 of the injector 6 and used as a working fluid of the needle valve 5 and finally through the leak passage 23. Collection system 24
Be escaped to. A pressure sensor 25 is provided in the low pressure chamber 4, and an opening / closing valve 26 (electromagnetic valve) is provided in the connection passage 18.
【0024】インジェクタ6は、高圧室3内の高圧の燃
料を噴射燃料として用い、低圧室4内の低圧の燃料を針
弁5の作動流体として用いるものである。インジェクタ
6の内部には、軸方向に移動自在な針弁5が収容されて
おり、その針弁5の先端側に噴射室19が形成され、根
元側に制御室22が形成されている。詳しくは、噴射室
19は、針弁5のコーン部27を囲繞するように形成さ
れており、制御室22は、針弁5のピストン部28を案
内するシリンダ29に形成されている。また、針弁5
は、コイルスプリング30により閉弁(下降)方向に付
勢されている。The injector 6 uses the high-pressure fuel in the high-pressure chamber 3 as an injection fuel and the low-pressure fuel in the low-pressure chamber 4 as a working fluid for the needle valve 5. Inside the injector 6, a needle valve 5 that is movable in the axial direction is housed, an injection chamber 19 is formed at the tip end side of the needle valve 5, and a control chamber 22 is formed at the root side. Specifically, the injection chamber 19 is formed so as to surround the cone portion 27 of the needle valve 5, and the control chamber 22 is formed in a cylinder 29 that guides the piston portion 28 of the needle valve 5. Also, the needle valve 5
Is biased in the valve closing (down) direction by the coil spring 30.
【0025】制御室22には、二股通路31が接続され
ており、その一方31aにオリフィス32が設けられ、
他方31bに逆止弁33が設けられている。かかる二股
通路31a,31bは再び集合され、その集合路34が
三方弁35(電磁弁)を介してリーク通路23と制御通
路21とに接続されている。三方弁35は、制御通路2
1と集合路34(制御室22)とを連通するフィード状
態と、リーク通路23と集合路34(制御室22)とを
連通するリーク状態とを切り替える。リーク通路23
は、制御室22内の燃料を回収系24に逃がすための通
路である。A forked passage 31 is connected to the control chamber 22, and an orifice 32 is provided in one of the passages 31a,
The check valve 33 is provided on the other side 31b. The bifurcated passages 31a and 31b are reassembled, and the assembly passage 34 is connected to the leak passage 23 and the control passage 21 via the three-way valve 35 (electromagnetic valve). The three-way valve 35 is connected to the control passage 2
1 is switched between a feed state that communicates the collecting passage 34 (control chamber 22) and a leak state that communicates the leak passage 23 and the collecting passage 34 (control chamber 22). Leak passage 23
Is a passage for allowing the fuel in the control chamber 22 to escape to the recovery system 24.
【0026】このような構成のインジェクタ6の針弁5
は、噴射室19内の燃圧によって上昇(開弁)方向に付
勢され、制御室22内の燃圧およびコイルスプリング2
0によって下降(閉弁)方向に付勢される。よって、上
下室19,22内の燃圧がバランスしている状態から三
方弁35をリーク状態とすると、圧力バランスが崩れて
針弁5が上昇し、噴射室19内の燃料がノズル先端部の
噴射口20から噴射される。その後、三方弁35をフィ
ード状態に切り替えると、再び上下の圧力がバランス
し、針弁5が下降して噴射口20を塞ぎ、噴射が終了す
る。Needle valve 5 of injector 6 having such a configuration
Is urged in the rising (valve opening) direction by the fuel pressure in the injection chamber 19, and the fuel pressure in the control chamber 22 and the coil spring 2
It is urged in the descending (valve closing) direction by 0. Therefore, if the three-way valve 35 is brought into a leak state from the state where the fuel pressures in the upper and lower chambers 19, 22 are balanced, the pressure balance is broken and the needle valve 5 rises, so that the fuel in the injection chamber 19 is injected at the nozzle tip portion. Ejected from the mouth 20. After that, when the three-way valve 35 is switched to the feed state, the upper and lower pressures are balanced again, the needle valve 5 descends to close the injection port 20, and the injection ends.
【0027】上記高圧室3の圧力センサ21a、低圧室
4の圧力センサ25、エンジン速度とカム角度のセンサ
36、噴射すべきシリンダを選択するセンサ37、エン
ジンの負荷のセンサ38、その他様々なエンジンの運転
情報(吸入空気量など)を検出するセンサが、コントロ
ールユニット39(ECU)に接続されている。コント
ロールユニット39は、これらの情報に基づいて、適
宜、インジェクタ6の三方弁35、連結通路18の開閉
弁26、高圧ポンプ2の開閉弁15を制御する。The pressure sensor 21a for the high pressure chamber 3, the pressure sensor 25 for the low pressure chamber 4, the engine speed and cam angle sensor 36, the cylinder selection sensor 37, the engine load sensor 38, and various other engines. A sensor that detects the operating information (such as the intake air amount) is connected to the control unit 39 (ECU). The control unit 39 appropriately controls the three-way valve 35 of the injector 6, the opening / closing valve 26 of the connecting passage 18, and the opening / closing valve 15 of the high-pressure pump 2 based on these pieces of information.
【0028】具体的には、コントロールユニット39
は、高圧室3の圧力センサ21aの検出値に基づいて高
圧ポンプ2の開閉弁15を制御し、プランジャ8で加圧
された燃料の一部を返流通路14を介して流入通路12
側に返流することにより、高圧室3内を略一定の燃圧
( 1200bar程度)にコントロールする。また、コントロ
ールユニット39は、低圧室4内を次のようにして略一
定の燃圧(600bar程度)にコントロールする。Specifically, the control unit 39
Controls the on-off valve 15 of the high-pressure pump 2 based on the detection value of the pressure sensor 21a of the high-pressure chamber 3 so that a part of the fuel pressurized by the plunger 8 is introduced into the inflow passage 12 via the return passage 14.
By returning to the side, the inside of the high-pressure chamber 3 is controlled to have a substantially constant fuel pressure (about 1200 bar). Further, the control unit 39 controls the inside of the low pressure chamber 4 to a substantially constant fuel pressure (about 600 bar) as follows.
【0029】図2に示すように、まず高圧室3の圧力P
1 と低圧室4の圧力P2 とをそれぞれ圧力センサ21
a,25で検出する。そして、 (P1 /n) >P1 を判
定する。ここで、nは高圧室3と低圧室4との圧力比で
あり、通常2〜4程度に設定される。そして、この判定
がイエスならば連結通路18の開閉弁26を開き、ノウ
ならば連結通路18の開閉弁26を閉じる。かかる制御
によって、高圧室3と低圧室4との圧力比をnに保つこ
とができる。As shown in FIG. 2, first, the pressure P in the high pressure chamber 3 is set.
1 and the pressure P 2 of the low pressure chamber 4 are respectively detected by the pressure sensor 21.
It is detected by a and 25. Then, (P 1 / n)> P 1 is determined. Here, n is a pressure ratio between the high pressure chamber 3 and the low pressure chamber 4, and is usually set to about 2 to 4. If the determination is yes, the open / close valve 26 of the connecting passage 18 is opened, and if the determination is no, the open / close valve 26 of the connecting passage 18 is closed. By such control, the pressure ratio between the high pressure chamber 3 and the low pressure chamber 4 can be maintained at n.
【0030】従って、このフローによれば、高圧室3の
燃圧を高圧ポンプ2の開閉弁15の開閉制御によって一
定(例えば 1200bar程度)に保っておけば、低圧室4の
燃圧をその1/nに保つことができる。本実施例におい
てはn=2としているため、低圧室4の燃圧は600bar程
度に保たれている。Therefore, according to this flow, if the fuel pressure in the high pressure chamber 3 is kept constant (for example, about 1200 bar) by the opening / closing control of the opening / closing valve 15 of the high pressure pump 2, the fuel pressure in the low pressure chamber 4 becomes 1 / n thereof. Can be kept at In this embodiment, since n = 2, the fuel pressure in the low pressure chamber 4 is maintained at about 600 bar.
【0031】また、コントロールユニット39は、エン
ジン速度とカム角度のセンサ36等から得られた情報に
基づいて、インジェクタ6の三方弁35をフィード状態
とリーク状態とに適宜切り替える。リーク状態にすると
前述したように針弁5が上昇して噴射室19内の燃料が
ノズル先端部の噴射口20から噴射され、フィード状態
にすると針弁5が下降して噴射口20を塞ぐ。Further, the control unit 39 appropriately switches the three-way valve 35 of the injector 6 between the feed state and the leak state based on the information obtained from the engine speed and the cam angle sensor 36 and the like. In the leak state, the needle valve 5 rises and the fuel in the injection chamber 19 is injected from the injection port 20 at the tip of the nozzle as described above, and in the feed state, the needle valve 5 descends to close the injection port 20.
【0032】以上の構成からなる本実施例の作用につい
て述べる。The operation of this embodiment having the above configuration will be described.
【0033】高圧室3内の高圧( 1200bar程度)の燃料
は、噴射通路17を通って針弁5先端側の噴射室19に
導入され、針弁5のリフト時に高圧状態で噴射される。
他方、低圧室4内の低圧(600bar程度)の燃料は、制御
通路21を通って三方弁35のフィード状態時に針弁5
根元側の制御室22に導入され、針弁5の作動流体とし
て用いられた後、三方弁35のリーク状態時に低圧状態
でリーク通路23に逃がされる。The high-pressure (about 1200 bar) fuel in the high-pressure chamber 3 is introduced into the injection chamber 19 on the tip side of the needle valve 5 through the injection passage 17, and is injected in a high pressure state when the needle valve 5 is lifted.
On the other hand, the low-pressure (about 600 bar) fuel in the low-pressure chamber 4 passes through the control passage 21 and the needle valve 5 when the three-way valve 35 is in the feed state.
After being introduced into the control chamber 22 on the root side and used as a working fluid for the needle valve 5, the three-way valve 35 is released to the leak passage 23 in a low pressure state when the valve is in a leak state.
【0034】このように、高圧室3内の高圧の燃料を噴
射燃料として用い、低圧室4内の低圧の燃料を針弁5の
作動流体として用いているので、燃料噴射圧が高まり、
同時にリーク燃料量が低減する。すなわち、噴射圧の高
圧化とリーク燃料量の低減とを両立できる。このよう
に、噴射圧を高めてもリーク燃料量が低減するため、高
圧ポンプ2の無駄仕事が少なくなり、燃費が向上する。
同時に、三方弁35(電磁弁)の消費電流も低減する。As described above, since the high pressure fuel in the high pressure chamber 3 is used as the injection fuel and the low pressure fuel in the low pressure chamber 4 is used as the working fluid of the needle valve 5, the fuel injection pressure increases,
At the same time, the amount of leaked fuel is reduced. That is, it is possible to achieve both high injection pressure and low leak fuel amount. In this way, the amount of leaked fuel is reduced even if the injection pressure is increased, so that wasteful work of the high-pressure pump 2 is reduced and fuel consumption is improved.
At the same time, the current consumption of the three-way valve 35 (solenoid valve) is also reduced.
【0035】また、三方弁35には、低圧の燃料が作動
流体として供給されるため、三方弁35の内部にコジリ
や変形等が生じる虞はなく、その耐久性・信頼性が向上
する。また、コジリ等に起因して三方弁35の作動がし
ぶくなることはなく、噴射圧を高めても三方弁35の作
動応答性を良好に維持できる。Further, since the low-pressure fuel is supplied to the three-way valve 35 as a working fluid, there is no possibility that the inside of the three-way valve 35 will be twisted or deformed, and its durability and reliability will be improved. Further, the operation of the three-way valve 35 does not become uncomfortable due to bending and the operation response of the three-way valve 35 can be favorably maintained even if the injection pressure is increased.
【0036】また、針弁5の開閉に応じて噴射室19内
の圧力が変動するが、その変動は噴射通路17を介して
高圧室3および低圧室4によって緩衝された後、制御通
路21を介して三方弁35に伝達されるため、三方弁3
5にダメージが生じることはない。また、このように制
御通路21内の圧力を針弁5の開閉に拘らず一定に保持
できるので、三方弁35をフィード状態とリーク状態に
精度よく制御できる。Further, the pressure in the injection chamber 19 fluctuates according to the opening and closing of the needle valve 5. The fluctuation is buffered by the high pressure chamber 3 and the low pressure chamber 4 via the injection passage 17, and then the control passage 21 is closed. Is transmitted to the three-way valve 35 via the three-way valve 3
There is no damage to 5. Further, since the pressure in the control passage 21 can be kept constant regardless of whether the needle valve 5 is opened or closed in this way, the three-way valve 35 can be accurately controlled in the feed state and the leak state.
【0037】〔変形実施例1〕次に、特許請求の範囲第
2項に係る実施例を図5に示す。[Modified Embodiment 1] FIG. 5 shows an embodiment according to claim 2 of the present invention.
【0038】図示するようにこの実施例は、前実施例と
その基本構成が同一であるため、同一の部材については
同一の符号を用いてその説明を省略し、相違点のみを以
下に説明する。As shown in the figure, this embodiment has the same basic structure as the previous embodiment, and therefore the same members are designated by the same reference numerals and their description is omitted, and only the differences will be described below. .
【0039】まず、インジェクタ6の噴射通路17と制
御通路21とが、一方向弁40を有するバイパス通路4
1によって接続されている。そして、そのバイパス通路
41の接続部42より上流側の噴射通路17aに、第1
開閉弁43が設けられている。そして、前実施例におけ
る三方弁35が、特許請求の範囲第2項の第2開閉弁に
相当する。三方弁35は、そのリーク時に、制御室22
内の燃料をリーク通路23を介して回収系24に逃がす
機能を発揮するからである。First, the injection passage 17 and the control passage 21 of the injector 6 are the bypass passage 4 having the one-way valve 40.
Connected by 1. Then, the first passage is provided in the injection passage 17a upstream of the connecting portion 42 of the bypass passage 41.
An on-off valve 43 is provided. The three-way valve 35 in the previous embodiment corresponds to the second opening / closing valve in claim 2. The three-way valve 35, when leaking, controls the control chamber 22.
This is because the function of letting the fuel inside escape to the recovery system 24 via the leak passage 23 is exhibited.
【0040】以上の構成からなる本実施例の作用につい
て述べる。The operation of this embodiment having the above configuration will be described.
【0041】図5において、まず、噴射通路17aの第
1開閉弁43を閉じ、インジェクタの三方弁をフィード
状態としておく。そして、三方弁35をリーク状態に切
り替える。すると、制御室22内の燃料がリーク通路2
3を通って回収系24へ逃がされ、針弁5がリフトして
噴射室19内の燃料が噴射される。このとき、噴射室1
9内には、低圧室4の低圧の燃料が制御通路21→バイ
パス通路41→噴射通路17を通って供給されているた
め、低圧燃料噴射となる。In FIG. 5, first, the first opening / closing valve 43 of the injection passage 17a is closed, and the three-way valve of the injector is in the feed state. Then, the three-way valve 35 is switched to the leak state. Then, the fuel in the control chamber 22 leaks into the leak passage 2
3 is discharged to the recovery system 24, the needle valve 5 is lifted, and the fuel in the injection chamber 19 is injected. At this time, the injection chamber 1
Since the low-pressure fuel in the low-pressure chamber 4 is supplied into the chamber 9 through the control passage 21 → the bypass passage 41 → the injection passage 17, low-pressure fuel injection is performed.
【0042】その後、第1開閉弁43を開くと、高圧室
3の高圧の燃料が噴射通路17a,17を通って噴射室
19に供給されるため、高圧燃料噴射となる。かかる噴
射圧の変化を図3に示す。図示するように、T1 のとき
に三方弁35をリーク状態に切り替えて低圧噴射
(PL )を行い、T2 のときに第1開閉弁43を開いて
高圧噴射(PH )を行い、T3 のときに第1開閉弁43
を閉じると共に三方弁35をフィード状態に切り替え
て、噴射を終了する。After that, when the first on-off valve 43 is opened, the high-pressure fuel in the high-pressure chamber 3 is supplied to the injection chamber 19 through the injection passages 17a, 17, so that high-pressure fuel injection is performed. Such changes in the injection pressure are shown in FIG. As shown in the figure, at T 1 , the three-way valve 35 is switched to the leak state to perform low pressure injection (P L ), and at T 2 , the first opening / closing valve 43 is opened to perform high pressure injection (P H ), The first opening / closing valve 43 at the time of T 3
Is closed, the three-way valve 35 is switched to the feed state, and the injection is ended.
【0043】かかる2段階噴射により、燃焼初期におけ
る予混合燃焼が抑えられ、急激な燃焼温度の上昇が抑制
され、NOxが低減する。The two-stage injection suppresses premixed combustion at the initial stage of combustion, suppresses a rapid rise in combustion temperature, and reduces NOx.
【0044】〔変形実施例2〕次に、特許請求の範囲第
3項に係る実施例を図6に示す。[Modified Embodiment 2] FIG. 6 shows an embodiment according to claim 3 of the present invention.
【0045】図示するようにこの実施例は、前実施例と
その基本構成が同一であり、第1開閉弁43より下流側
でバイパス通路41の接続部42より上流側の噴射通路
17bに、絞り部44を設けた点のみが異なっている。As shown in the figure, this embodiment has the same basic construction as the previous embodiment, and restricts the injection passage 17b downstream of the first opening / closing valve 43 and upstream of the connecting portion 42 of the bypass passage 41. The only difference is that the portion 44 is provided.
【0046】この構成によれば、第1開閉弁43を開く
高圧燃料噴射の際に、噴射通路17bを流れる燃料が絞
り部44によって絞られるので、高圧燃料噴射時の噴射
立上り特性がなだらかになる。その様子を図4に示す。
図示するように、t1 のときに三方弁35をリーク状態
に切り替えて低圧噴射(pl )を行い、t2 のときに第
1開閉弁43を開いて高圧噴射(ph )をなだらかに行
い、t3 のときに第1開閉弁43を閉じると共に三方弁
35をフィード状態に切り替えて、噴射を終了する。According to this structure, at the time of high-pressure fuel injection for opening the first on-off valve 43, the fuel flowing through the injection passage 17b is throttled by the throttle portion 44, so that the injection rising characteristic at the time of high-pressure fuel injection becomes gentle. . This is shown in FIG.
As shown in the figure, at t 1 , the three-way valve 35 is switched to the leak state to perform low-pressure injection ( pl ), and at t 2 , the first on-off valve 43 is opened to smoothly perform high-pressure injection ( ph ). Then, at t 3 , the first on-off valve 43 is closed, the three-way valve 35 is switched to the feed state, and the injection is finished.
【0047】このように、高圧燃料噴射時の噴射立上り
特性がなだらかになると、予混合燃焼時の急激な燃焼温
度の上昇が抑制され、NOxがさらに低減する。As described above, when the injection rising characteristic at the time of high-pressure fuel injection becomes gentle, the rapid increase of the combustion temperature at the time of premixed combustion is suppressed, and NOx is further reduced.
【0048】[0048]
【発明の効果】以上説明したように本発明に係る蓄圧式
燃料噴射装置によれば、次のような優れた効果を発揮で
きる。As described above, according to the pressure-accumulation type fuel injection device of the present invention, the following excellent effects can be exhibited.
【0049】(1)請求項1記載の発明によれば、高圧室
内の高圧の燃料を噴射燃料として用い、低圧室内の低圧
の燃料を針弁の作動流体として用いているので、噴射圧
の高圧化とリーク燃料量の低減とを両立できる。(1) According to the first aspect of the invention, the high pressure fuel in the high pressure chamber is used as the injection fuel, and the low pressure fuel in the low pressure chamber is used as the working fluid for the needle valve. And reduction of the amount of leaked fuel can be achieved at the same time.
【0050】(2)請求項2記載の発明によれば、第1開
閉弁と第2開閉弁とを連続して開閉制御することによ
り、低圧噴射に繋げて高圧噴射することができる。よっ
て、燃焼初期における予混合燃焼を抑制でき、急激な燃
焼温度の上昇を抑制できるため、NOxを低減できる。(2) According to the second aspect of the present invention, by controlling the opening and closing of the first opening / closing valve and the second opening / closing valve continuously, it is possible to perform high pressure injection linked to low pressure injection. Therefore, the premixed combustion in the early stage of combustion can be suppressed, and the rapid increase in the combustion temperature can be suppressed, so that NOx can be reduced.
【0051】(3)請求項3記載の発明によれば、絞り部
が高圧燃料噴射の際に噴射通路を流れる燃料を絞るた
め、高圧燃料噴射時の噴射立上り特性をなだらかにでき
る。よって、予混合燃焼時の急激な燃焼温度の上昇を抑
制でき、NOxをさらに低減できる。(3) According to the third aspect of the invention, since the throttle portion throttles the fuel flowing through the injection passage at the time of high-pressure fuel injection, the injection rising characteristic at the time of high-pressure fuel injection can be made gentle. Therefore, a rapid increase in combustion temperature during premixed combustion can be suppressed, and NOx can be further reduced.
【図1】本発明の一実施例を示す蓄圧式燃料噴射装置の
説明図である(請求項1)。FIG. 1 is an explanatory view of a pressure-accumulation type fuel injection device showing an embodiment of the present invention (claim 1).
【図2】高圧室と低圧室との間に設けられた開閉弁の制
御フローを示す図である。FIG. 2 is a diagram showing a control flow of an opening / closing valve provided between a high pressure chamber and a low pressure chamber.
【図3】図5に示す蓄圧式燃料噴射装置の噴射特性を示
す図である。FIG. 3 is a diagram showing injection characteristics of the pressure accumulation type fuel injection device shown in FIG.
【図4】図6に示す蓄圧式燃料噴射装置の噴射特性を示
す図である。FIG. 4 is a diagram showing injection characteristics of the pressure accumulation type fuel injection device shown in FIG. 6.
【図5】変形実施例を示す蓄圧式燃料噴射装置の説明図
である(請求項2)。FIG. 5 is an explanatory view of a pressure accumulation type fuel injection device showing a modified embodiment (claim 2).
【図6】別の変形実施例を示す蓄圧式燃料噴射装置の説
明図である(請求項3)。FIG. 6 is an explanatory view of a pressure-accumulation type fuel injection device showing another modified embodiment (claim 3).
【図7】従来例を示す蓄圧式燃料噴射装置の説明図であ
る。FIG. 7 is an explanatory view of a pressure accumulation type fuel injection device showing a conventional example.
【図8】従来の蓄圧式燃料噴射装置のインジェクタの概
要を示す図である。FIG. 8 is a diagram showing an outline of an injector of a conventional pressure accumulation type fuel injection device.
3 高圧室 4 低圧室 5 針弁 17 噴射通路 19 噴射室 21 制御通路 22 制御室 23 リーク通路 24 回収系 35 第2開閉弁としての三方弁 41 バイパス通路 42 接続部 43 第1開閉弁 44 絞り部 3 High-pressure chamber 4 Low-pressure chamber 5 Needle valve 17 Injection passageway 19 Injection chamber 21 Control passageway 22 Control chamber 23 Leakage passageway 24 Recovery system 35 Three-way valve as second opening / closing valve 41 Bypass passageway 42 Connection portion 43 First opening / closing valve 44 Throttling portion
─────────────────────────────────────────────────────
─────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成8年2月23日[Submission date] February 23, 1996
【手続補正1】[Procedure Amendment 1]
【補正対象書類名】図面[Document name to be corrected] Drawing
【補正対象項目名】図7[Name of item to be corrected] Figure 7
【補正方法】変更[Correction method] Change
【補正内容】[Correction content]
【図7】 [Figure 7]
Claims (3)
の噴射室と針弁根元側の制御室とに導き、その制御室内
の燃料を回収系に逃がすことにより針弁をリフトさせ、
噴射室内の燃料を噴射する蓄圧式燃料噴射装置におい
て、上記蓄圧室を高圧室と低圧室とに分割し、その高圧
室と上記噴射室とを接続する噴射通路を設けると共に、
低圧室と上記制御室とを接続する制御通路を設けたこと
を特徴とする蓄圧式燃料噴射装置。1. A needle valve is lifted by guiding fuel stored in a pressure accumulating chamber to an injection chamber on the needle valve tip side and a control chamber on the needle valve base side, and letting the fuel in the control chamber escape to a recovery system,
In a pressure accumulation type fuel injection device for injecting fuel in an injection chamber, the pressure accumulation chamber is divided into a high pressure chamber and a low pressure chamber, and an injection passage connecting the high pressure chamber and the injection chamber is provided,
A pressure-accumulation fuel injection device comprising a control passage that connects the low-pressure chamber and the control chamber.
イパス通路を設け、そのバイパス通路の接続部より上流
側の噴射通路に第1開閉弁を設け、上記制御室内の燃料
を回収系へ逃がすリーク通路に第2開閉弁を設けた請求
項1記載の蓄圧式燃料噴射装置。2. A bypass passage that connects the injection passage and the control passage is provided, and a first opening / closing valve is provided in the injection passage upstream of the connection portion of the bypass passage to allow the fuel in the control chamber to escape to the recovery system. The pressure-accumulation fuel injection device according to claim 1, wherein a second opening / closing valve is provided in the leak passage.
路の接続部より上流側の噴射通路に、絞り部を設けた請
求項2記載の蓄圧式燃料噴射装置。3. The pressure-accumulation fuel injection device according to claim 2, wherein a throttle portion is provided in an injection passage downstream of the first opening / closing valve and upstream of a connection portion of the bypass passage.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10604895A JPH08296520A (en) | 1995-04-28 | 1995-04-28 | Accumulator fuel injection device |
US08/633,632 US5732679A (en) | 1995-04-27 | 1996-04-17 | Accumulator-type fuel injection system |
EP98121205A EP0909892A3 (en) | 1995-04-27 | 1996-04-24 | Accumulator-type fuel injection system |
DE69605075T DE69605075T2 (en) | 1995-04-27 | 1996-04-24 | Fuel injection device of the accumulator type |
EP96106453A EP0740067B1 (en) | 1995-04-27 | 1996-04-24 | Accumulator-type fuel injection system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10604895A JPH08296520A (en) | 1995-04-28 | 1995-04-28 | Accumulator fuel injection device |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH08296520A true JPH08296520A (en) | 1996-11-12 |
Family
ID=14423752
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP10604895A Pending JPH08296520A (en) | 1995-04-27 | 1995-04-28 | Accumulator fuel injection device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH08296520A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008121545A (en) * | 2006-11-10 | 2008-05-29 | Mitsubishi Heavy Ind Ltd | Fuel injection device |
JP2009515094A (en) * | 2005-11-09 | 2009-04-09 | キャタピラー インコーポレイテッド | Multi-source fuel system for variable pressure injection |
WO2009072346A1 (en) * | 2007-12-05 | 2009-06-11 | Mitsubishi Heavy Industries, Ltd. | Fuel injection valve for pressure accumulation-type fuel injection device |
-
1995
- 1995-04-28 JP JP10604895A patent/JPH08296520A/en active Pending
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009515094A (en) * | 2005-11-09 | 2009-04-09 | キャタピラー インコーポレイテッド | Multi-source fuel system for variable pressure injection |
JP2008121545A (en) * | 2006-11-10 | 2008-05-29 | Mitsubishi Heavy Ind Ltd | Fuel injection device |
WO2009072346A1 (en) * | 2007-12-05 | 2009-06-11 | Mitsubishi Heavy Industries, Ltd. | Fuel injection valve for pressure accumulation-type fuel injection device |
US8602322B2 (en) | 2007-12-05 | 2013-12-10 | Mitsubishi Heavy Industries, Ltd. | Fuel injection valve of accumulator injection system |
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