JP4329704B2 - Fuel injection device - Google Patents

Fuel injection device Download PDF

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JP4329704B2
JP4329704B2 JP2005047097A JP2005047097A JP4329704B2 JP 4329704 B2 JP4329704 B2 JP 4329704B2 JP 2005047097 A JP2005047097 A JP 2005047097A JP 2005047097 A JP2005047097 A JP 2005047097A JP 4329704 B2 JP4329704 B2 JP 4329704B2
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pressure
common rail
fuel
valve
fuel injection
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JP2006233805A (en
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辰巳 古久保
嘉紀 太長根
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Toyota Motor Corp
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Toyota Motor Corp
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    • 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
    • F02M63/0275—Arrangement of common rails
    • F02M63/0285—Arrangement of common rails having more than one common rail
    • F02M63/029—Arrangement of common rails having more than one common rail per cylinder bank, e.g. storing different fuels or fuels at different pressure levels per cylinder bank
    • 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
    • F02M57/00—Fuel-injectors combined or associated with other devices
    • F02M57/02—Injectors structurally combined with fuel-injection pumps
    • F02M57/022—Injectors structurally combined with fuel-injection pumps characterised by the pump drive
    • F02M57/025—Injectors structurally combined with fuel-injection pumps characterised by the pump drive hydraulic, e.g. with pressure amplification
    • 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
    • F02M63/0003—Fuel-injection apparatus having a cyclically-operated valve for connecting a pressure source, e.g. constant pressure pump or accumulator, to an injection valve held closed mechanically, e.g. by springs, and automatically opened by fuel pressure
    • F02M63/0007—Fuel-injection apparatus having a cyclically-operated valve for connecting a pressure source, e.g. constant pressure pump or accumulator, to an injection valve held closed mechanically, e.g. by springs, and automatically opened by fuel pressure using electrically actuated valves
    • 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
    • F02M63/0012—Valves
    • F02M63/0031—Valves characterized by the type of valves, e.g. special valve member details, valve seat details, valve housing details
    • F02M63/0045—Three-way valves
    • 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
    • F02M63/0012—Valves
    • F02M63/0031—Valves characterized by the type of valves, e.g. special valve member details, valve seat details, valve housing details
    • F02M63/0049—Combined valve units, e.g. for controlling pumping chamber and injection valve

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)

Description

本発明は燃料噴射装置に関する。   The present invention relates to a fuel injection device.

コモンレールに連結された燃料噴射弁を具備し、各燃料噴射弁が燃料噴射圧を増大するための増圧ピストンを備えており、この増圧ピストンは同軸上において整列配置された大径ピストンと小径ピストンからなると共に大径ピストンの小径ピストン側の端面上に中間室が形成されており、この中間室は流路切替弁によってコモンレールおよび燃料排出通路のいずれか一方に連結され、コモンレールから増圧ピストンの中間室に導びかれた高圧の燃料を中間室から排出させることにより燃料噴射圧の増大作用が行われる燃料噴射装置が公知である（例えば特許文献１参照）。
特開平１０−２３８４３２号公報 A fuel injection valve connected to a common rail is provided, and each fuel injection valve has a booster piston for increasing the fuel injection pressure. The booster piston is coaxially arranged with a large-diameter piston and a small-diameter An intermediate chamber is formed on the end surface of the large-diameter piston on the small-diameter piston side, and this intermediate chamber is connected to either the common rail or the fuel discharge passage by a flow path switching valve. 2. Description of the Related Art A fuel injection device is known in which a fuel injection pressure is increased by discharging high-pressure fuel guided to the intermediate chamber from the intermediate chamber (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-238432

ところで増圧ピストンにより燃料噴射圧の増大作用を行うには上述したようにコモンレールから中間室に送り込まれた高圧の燃料を中間室から排出しなければならず、従ってコモンレールから燃料噴射弁に供給すべき燃料量は増圧ピストンを備えていない通常の燃料噴射装置に比べて大巾に増大する。この場合、コモンレールの容積が小さすぎると燃料噴射が行われたときやコモンレールから高圧の燃料が中間室に送り込まれたときにコモンレール内の燃料圧が大巾に低下し、その結果増圧ピストンによる噴射圧増大時の噴射圧が低下してしまう。このように噴射圧増大時に噴射圧が低下してしまうのを阻止するためにはコモンレールの容積を大きくしなければならない。しかしながらコモンレールの容積を大きくすると機関始動時にコモンレールの燃料を昇圧させるのに時間を要し、斯くして良好な機関の始動が確保できないという問題がある。   By the way, in order to increase the fuel injection pressure by the pressure-increasing piston, as described above, the high-pressure fuel fed from the common rail to the intermediate chamber must be discharged from the intermediate chamber, and therefore supplied from the common rail to the fuel injection valve. The amount of fuel to be increased greatly increases as compared with a normal fuel injection device not provided with a pressure-increasing piston. In this case, if the volume of the common rail is too small, the fuel pressure in the common rail is greatly reduced when fuel injection is performed or when high-pressure fuel is sent from the common rail to the intermediate chamber. The injection pressure when the injection pressure increases will decrease. Thus, in order to prevent the injection pressure from decreasing when the injection pressure increases, the volume of the common rail must be increased. However, if the volume of the common rail is increased, it takes time to boost the pressure of the common rail fuel at the time of engine start, and thus there is a problem that good engine start cannot be ensured.

上記問題点を解決するために本発明によれば、コモンレールに連結された燃料噴射弁を具備し、燃料噴射弁が燃料噴射圧を増大するための増圧ピストンを備えており、コモンレールから増圧ピストンの中間室に導びかれた高圧の燃料を中間室から排出させることにより燃料噴射圧の増大作用が行われる燃料噴射装置において、コモンレールを互いに分離された第１のコモンレールと第２のコモンレールから構成し、機関始動時には第１のコモンレールと第２のコモンレールの連通を遮断して燃料ポンプから第１のコモンレールのみに高圧の燃料を供給すると共に、機関始動後暫らくして第２のコモンレールの燃料圧も上昇すべきであると判断されたときには燃料ポンプから第２のコモンレールにも高圧の燃料を供給し、燃料噴射弁のニードル弁の圧力制御室および増圧ピストンの中間室が二位置切替弁を介して第１のコモンレールおよび燃料排出通路のいずれか一方に選択的に連結され、中間室と二位置切替弁間に通路開閉弁が配置され、二位置切替弁の切替作用によってニードル弁の圧力制御室が第１のコモンレールに連結されたときにはニードル弁が閉弁して燃料噴射が停止されると共に圧力制御室が燃料排出通路に連結されたときにはニードル弁が開弁して燃料噴射が行われ、二位置切替弁の切替作用によって増圧ピストンの中間室が燃料排出通路に連結されたときに通路開閉弁が閉弁していれば増圧ピストンの作動が停止され、このとき通路開閉弁が開弁していれば中間室内の高圧の燃料が燃料排出通路内に排出されて増圧ピストンが作動せしめられる。
また、上記問題点を解決するために本発明によれば、コモンレールに連結された燃料噴射弁を具備し、燃料噴射弁が燃料噴射圧を増大するための増圧ピストンを備えており、コモンレールから増圧ピストンの中間室に導びかれた高圧の燃料を中間室から排出させることにより燃料噴射圧の増大作用が行われる燃料噴射装置において、コモンレールを互いに分離された第１のコモンレールと第２のコモンレールから構成し、機関始動時には第１のコモンレールと第２のコモンレールの連通を遮断して燃料ポンプから第１のコモンレールのみに高圧の燃料を供給すると共に、機関始動後暫らくして第２のコモンレールの燃料圧も上昇すべきであると判断されたときには燃料ポンプから第２のコモンレールにも高圧の燃料を供給し、燃料噴射弁のニードル弁の圧力制御室および増圧ピストンの中間室が三位置切替弁を介して第１のコモンレールおよび燃料排出通路のいずれか一方に選択的に連結され、三位置切替弁の切替作用によってニードル弁の圧力制御室が第１のコモンレールに連結されたときにはニードル弁が閉弁して燃料噴射が停止され、三位置切替弁の切替作用によってニードル弁の圧力制御室および増圧ピストンの中間室が共に燃料排出通路に連結されたときにはニードル弁が開弁して燃料噴射が行われると共に増圧ピストンが作動して燃料噴射圧が増大せしめられ、三位置切替弁の切替作用によってニードル弁の圧力制御室のみが燃料排出通路に連結されたときには増圧ピストンが作動することなくニードル弁が開弁して燃料噴射が行われる。 In order to solve the above problems, according to the present invention, a fuel injection valve connected to a common rail is provided, and the fuel injection valve includes a pressure increasing piston for increasing the fuel injection pressure. In a fuel injection device in which a fuel injection pressure is increased by discharging high-pressure fuel guided to an intermediate chamber of a piston from the intermediate chamber, the common rail is separated from the first common rail and the second common rail. And when the engine is started, the communication between the first common rail and the second common rail is cut off and high pressure fuel is supplied only from the fuel pump to the first common rail. fuel pressure also supplies high pressure fuel to the second common rail from the fuel pump when it is determined that it should increase, the fuel injection valve needle The pressure control chamber and the intermediate chamber of the boosting piston are selectively connected to either the first common rail or the fuel discharge passage via a two-position switching valve, and a passage opening / closing valve is provided between the intermediate chamber and the two-position switching valve. When the pressure control chamber of the needle valve is connected to the first common rail by the switching action of the two-position switching valve, the needle valve is closed to stop fuel injection and the pressure control chamber to the fuel discharge passage When connected, the needle valve opens and fuel injection is performed, and when the intermediate chamber of the booster piston is connected to the fuel discharge passage by the switching action of the two-position switching valve, the passage opening / closing valve is closed. Then, the operation of the pressure increasing piston is stopped, and if the passage opening / closing valve is open at this time, the high pressure fuel in the intermediate chamber is discharged into the fuel discharge passage and the pressure increasing piston is operated.
Further, in order to solve the above-described problems, according to the present invention, the fuel injection valve connected to the common rail is provided, and the fuel injection valve includes a pressure increasing piston for increasing the fuel injection pressure. In a fuel injection device in which a high-pressure fuel guided to an intermediate chamber of a booster piston is discharged from the intermediate chamber to increase the fuel injection pressure, the common rail is separated from each other by the first common rail and the second common rail. It is composed of a common rail, and when the engine is started, the communication between the first common rail and the second common rail is cut off and high pressure fuel is supplied only from the fuel pump to the first common rail. When it is determined that the fuel pressure of the common rail should also increase, high pressure fuel is supplied from the fuel pump to the second common rail, and the fuel injection valve is turned off. The pressure control chamber of the dollar valve and the intermediate chamber of the pressure increasing piston are selectively connected to either the first common rail or the fuel discharge passage via the three-position switching valve, and the needle valve is switched by the switching action of the three-position switching valve. When the pressure control chamber of the needle valve is connected to the first common rail, the needle valve is closed and fuel injection is stopped, and the pressure control chamber of the needle valve and the intermediate chamber of the pressure increasing piston are both connected by the switching action of the three-position switching valve. When connected to the fuel discharge passage, the needle valve opens to perform fuel injection, and the pressure increasing piston operates to increase the fuel injection pressure, and the pressure control chamber of the needle valve is switched by the switching action of the three-position switching valve. When only the fuel discharge passage is connected to the fuel discharge passage, the needle valve opens without operating the pressure-increasing piston, and fuel injection is performed.

増圧ピストンによる良好な燃料噴射圧の増大作用を確保しつつ機関の良好な始動を確保することができる。   It is possible to ensure a good start of the engine while ensuring a good fuel injection pressure increasing action by the pressure increasing piston.

図１は燃料噴射装置の全体を図解的に示しており、図１において一点鎖線で囲まれた部分１はエンジンに取付けられた燃料噴射弁を示している。図１に示されるように本発明によれば高圧の燃料を貯留するためのコモンレールが互いに分離された第１のコモンレール２と第２のコモンレール３から構成され、第１のコモンレール２と第２のコモンレール３とを連通するコモンレール連通路４内には連通制御弁５が配置されている。図１に示す実施例ではこの連通制御弁５は第１のコモンレール２から第２のコモンレール３に向けてのみ流通可能でありかつ第１のコモンレール２内の燃料圧が予め定められた設定圧、例えば１００MPaを越えたときに開弁する調圧弁からなる。図１に示されるように第１のコモンレール２の容積は第２のコモンレール３の容積よりも小さく、第１のコモンレール２および第２のコモンレール３には夫々燃料圧センサ６，７が取付けられている。   FIG. 1 schematically shows the entire fuel injection apparatus, and a portion 1 surrounded by a one-dot chain line in FIG. 1 indicates a fuel injection valve attached to the engine. As shown in FIG. 1, according to the present invention, a common rail for storing high-pressure fuel is composed of a first common rail 2 and a second common rail 3 which are separated from each other, and the first common rail 2 and the second common rail 3 are separated from each other. A communication control valve 5 is disposed in a common rail communication path 4 that communicates with the common rail 3. In the embodiment shown in FIG. 1, the communication control valve 5 can only flow from the first common rail 2 toward the second common rail 3, and the fuel pressure in the first common rail 2 is set to a predetermined pressure, For example, it comprises a pressure regulating valve that opens when the pressure exceeds 100 MPa. As shown in FIG. 1, the volume of the first common rail 2 is smaller than the volume of the second common rail 3, and fuel pressure sensors 6 and 7 are attached to the first common rail 2 and the second common rail 3, respectively. Yes.

図１に示されるように第１のコモンレール２内には燃料タンク８内の燃料が高圧燃料ポンプ９を介して供給される。第１のコモンレール２内の燃料圧は高圧燃料ポンプ９の吐出量を制御することにより機関運転状態に応じた目標燃料圧に維持され、目標燃料圧に維持されている第１のコモンレール２内の高圧の燃料が高圧燃料供給通路１０を介して燃料噴射弁１に供給される。また、第２のコモンレール３内の燃料も燃料供給通路１１を介して燃料噴射弁１に供給される。   As shown in FIG. 1, the fuel in the fuel tank 8 is supplied into the first common rail 2 via the high-pressure fuel pump 9. The fuel pressure in the first common rail 2 is maintained at the target fuel pressure corresponding to the engine operating state by controlling the discharge amount of the high-pressure fuel pump 9, and the fuel pressure in the first common rail 2 maintained at the target fuel pressure. High-pressure fuel is supplied to the fuel injection valve 1 through the high-pressure fuel supply passage 10. Further, the fuel in the second common rail 3 is also supplied to the fuel injection valve 1 through the fuel supply passage 11.

図１に示されるように燃料噴射弁１は燃焼室内に燃料を噴射するためのノズル部１２と、噴射圧を増圧させるための増圧器１３と、燃料通路を切換えるための二位置切替弁、即ち三方弁１４とを具備している。ノズル部１２はニードル弁１５を備えており、ノズル部１２の先端にはニードル弁１５の先端部により開閉制御される噴口１６（図示せず）が形成されている。ニードル弁１５の周りには噴射される高圧燃料で満たされたノズル室１７が形成されており、ニードル弁１５の頂面上には燃料で満たされている圧力制御室１８が形成されている。圧力制御室１８内にはニードル弁１５を下方に向けて、即ち閉弁方向に付勢する圧縮ばね１９が挿入されており、この圧力制御室１８は燃料流通通路２０を介して三方弁１４に連結されている。また、ノズル室１７は燃料流通通路２１に連結され、この燃料流通通路２１は高圧燃料供給通路１０から燃料流通通路２１に向けてのみ流通可能な逆止弁２２を介して高圧燃料供給通路１０に連結されている。   As shown in FIG. 1, the fuel injection valve 1 includes a nozzle portion 12 for injecting fuel into the combustion chamber, a pressure intensifier 13 for increasing the injection pressure, a two-position switching valve for switching the fuel passage, That is, a three-way valve 14 is provided. The nozzle portion 12 includes a needle valve 15, and a nozzle hole 16 (not shown) that is controlled to open and close by the tip portion of the needle valve 15 is formed at the tip of the nozzle portion 12. A nozzle chamber 17 filled with high-pressure fuel to be injected is formed around the needle valve 15, and a pressure control chamber 18 filled with fuel is formed on the top surface of the needle valve 15. A compression spring 19 is inserted in the pressure control chamber 18 to urge the needle valve 15 downward, that is, in a valve closing direction. The pressure control chamber 18 is connected to the three-way valve 14 via a fuel circulation passage 20. It is connected. The nozzle chamber 17 is connected to a fuel circulation passage 21, and the fuel circulation passage 21 is connected to the high-pressure fuel supply passage 10 via a check valve 22 that can flow only from the high-pressure fuel supply passage 10 toward the fuel circulation passage 21. It is connected.

一方、増圧器１３は一体成形された大径ピストン２３と小径ピストン２４からなる増圧ピストン２５を具備する。小径ピストン２４と反対側の大径ピストン２３の頂面上には燃料で満たされた高圧室２６が形成されており、この高圧室２６は燃料供給通路１１を介して第２のコモンレール３に連結されている。従って高圧室２６内には常時第２のコモンレール３内の燃料圧が作用している。これに対し、小径ピストン２４周りの大径ピストン２３の端面上には燃料で満たされた中間室２７が形成されており、この中間室２７内には大径ピストン２３を高圧室２６に向けて付勢する圧縮ばね２８が挿入されている。この中間室２７は一方では絞り２９および燃料供給通路１１を介して第２のコモンレール３に連結されており、他方では燃料流通通路３０ｂ、通路開閉弁３１および燃料流通通路３０ａを介して燃料流通通路２０に連結されている。また、大径ピストン２３と反対側の小径ピストン２４の端面上には燃料で満たされた増圧室３２が形成されており、この増圧室３２は燃料流通通路２１に連結されている。   On the other hand, the pressure booster 13 includes a pressure boosting piston 25 including a large-diameter piston 23 and a small-diameter piston 24 which are integrally formed. A high-pressure chamber 26 filled with fuel is formed on the top surface of the large-diameter piston 23 opposite to the small-diameter piston 24, and the high-pressure chamber 26 is connected to the second common rail 3 via the fuel supply passage 11. Has been. Accordingly, the fuel pressure in the second common rail 3 is constantly acting in the high pressure chamber 26. On the other hand, an intermediate chamber 27 filled with fuel is formed on the end face of the large-diameter piston 23 around the small-diameter piston 24, and the large-diameter piston 23 faces the high-pressure chamber 26 in the intermediate chamber 27. An urging compression spring 28 is inserted. The intermediate chamber 27 is connected on the one hand to the second common rail 3 via the throttle 29 and the fuel supply passage 11, and on the other hand, the fuel circulation passage is connected to the fuel circulation passage 30b, the passage opening / closing valve 31 and the fuel circulation passage 30a. 20 is connected. A pressure increasing chamber 32 filled with fuel is formed on the end face of the small diameter piston 24 opposite to the large diameter piston 23, and the pressure increasing chamber 32 is connected to the fuel flow passage 21.

通路開閉弁３１はピストン３３と、ピストン３３に連結されかつ連通孔３４を形成した弁体３５とを具備する。弁体３５と反対側のピストン３３の端面上には圧力制御室３６が形成され、この圧力制御室３６は燃料供給通路３７および１１を介して第２のコモンレール３に連結される。一方、ピストン３３と反対側の弁体３５の端面上にはばね室３８が形成され、このばね室３８内には弁体３５を上方に向けて付勢する圧縮ばね３９が挿入される。このばね室３８も燃料供給通路３７，１１を介して第２のコモンレール３に連結される。また、弁体３５側のピストン３３の端面上にはピストン室４０が形成される。このピストン室４０は一方では絞り４１および燃料供給通路３７，１１を介して第２のコモンレール３に連結され、他方では燃料流通通路３０ａからピストン室４０に向けてのみ流通可能な逆止弁４２を介して燃料流通通路３０ａに連結される。   The passage opening / closing valve 31 includes a piston 33 and a valve body 35 connected to the piston 33 and having a communication hole 34. A pressure control chamber 36 is formed on the end surface of the piston 33 opposite to the valve body 35, and the pressure control chamber 36 is connected to the second common rail 3 via fuel supply passages 37 and 11. On the other hand, a spring chamber 38 is formed on the end surface of the valve body 35 opposite to the piston 33, and a compression spring 39 for urging the valve body 35 upward is inserted into the spring chamber 38. The spring chamber 38 is also connected to the second common rail 3 through the fuel supply passages 37 and 11. A piston chamber 40 is formed on the end face of the piston 33 on the valve body 35 side. The piston chamber 40 is connected to the second common rail 3 on the one hand via a throttle 41 and fuel supply passages 37 and 11, and on the other hand, a check valve 42 that can flow only from the fuel flow passage 30 a toward the piston chamber 40. To the fuel flow passage 30a.

一方、三方弁１４には高圧燃料供給通路１０および燃料流通通路２０に加え、例えば燃料タンク８内に接続された燃料排出通路４３が連結されている。この三方弁１４は電磁ソレノイド或いはピエゾ圧電素子のようなアクチュエータによって駆動され、この三方弁１４によって燃料流通通路２０が高圧燃料供給通路１０又は燃料排出通路４３に選択的に連結される。   On the other hand, in addition to the high-pressure fuel supply passage 10 and the fuel circulation passage 20, for example, a fuel discharge passage 43 connected to the fuel tank 8 is connected to the three-way valve 14. The three-way valve 14 is driven by an actuator such as an electromagnetic solenoid or a piezoelectric element, and the fuel flow passage 20 is selectively connected to the high-pressure fuel supply passage 10 or the fuel discharge passage 43 by the three-way valve 14.

機関の運転が停止すると第１のコモンレール２および第２のコモンレール３内の燃料は高圧燃料ポンプ９、増圧器１３、通路開閉弁３１、或いは三方弁１４内の微少隙間を通って燃料タンク８内に流出し、従って第１のコモンレール２および第２のコモンレール３内の燃料圧は次第に低下する。次いで機関の運転が再開され、即ち、機関が始動され、高圧燃料ポンプ９が駆動されると第１のコモンレール２内の燃料圧が上昇する。このとき調圧弁５は閉弁しており、また第１のコモンレール２は小さな容積を有するので第１のコモンレール２内の燃料圧は急速に上昇する。次いで第１のコモンレール２内の燃料圧が予め定められた設定圧を越えると調圧弁５が開弁する。その結果、第１のコモンレール２内の燃料がコモンレール連通路４を介して第２のコモンレール３内にも供給され、従って第２のコモンレール３内の燃料圧も上昇する。   When the operation of the engine is stopped, the fuel in the first common rail 2 and the second common rail 3 passes through a minute gap in the high-pressure fuel pump 9, the pressure intensifier 13, the passage opening / closing valve 31, or the three-way valve 14 and enters the fuel tank 8. Therefore, the fuel pressure in the first common rail 2 and the second common rail 3 gradually decreases. Next, when the operation of the engine is resumed, that is, when the engine is started and the high-pressure fuel pump 9 is driven, the fuel pressure in the first common rail 2 increases. At this time, the pressure regulating valve 5 is closed, and the first common rail 2 has a small volume, so that the fuel pressure in the first common rail 2 rises rapidly. Next, when the fuel pressure in the first common rail 2 exceeds a predetermined set pressure, the pressure regulating valve 5 is opened. As a result, the fuel in the first common rail 2 is also supplied into the second common rail 3 via the common rail communication path 4, and thus the fuel pressure in the second common rail 3 also increases.

次に、上述の如く第２のコモンレール３内の燃料圧が十分に高められたときの噴射制御、即ち通常運転時の噴射制御について最初に説明する。
図１は、三方弁１４による燃料通路切換作用によって燃料流通通路２０が高圧燃料供給通路１０に連結されている場合を示している。この場合にはノズル部１２の圧力制御室１８内の燃料圧は第１のコモンレール２内の燃料圧（第１コモンレール圧と称する）となっている。一方、ノズル部１２のノズル室１７内には逆止弁２２を介して第１のコモンレール２内の燃料圧が加わっており、従ってノズル室１７の燃料圧も第１コモンレール圧となっている。このときノズル室１７内の燃料圧によりニードル弁１５を上昇させる力よりも圧力制御室１８内の燃料圧および圧縮ばね１８のばね力によってニードル弁１５を下降させる力の方が強い。そのため、ニードル弁１５は下降せしめられており、その結果ニードル弁１５が閉弁するために噴口１６からの燃料噴射は停止されている。 Next, injection control when the fuel pressure in the second common rail 3 is sufficiently increased as described above, that is, injection control during normal operation will be described first.
FIG. 1 shows a case where the fuel circulation passage 20 is connected to the high-pressure fuel supply passage 10 by the fuel passage switching action by the three-way valve 14. In this case, the fuel pressure in the pressure control chamber 18 of the nozzle portion 12 is the fuel pressure in the first common rail 2 (referred to as the first common rail pressure). On the other hand, the fuel pressure in the first common rail 2 is applied to the nozzle chamber 17 of the nozzle portion 12 via the check valve 22, so the fuel pressure in the nozzle chamber 17 is also the first common rail pressure. At this time, the force of lowering the needle valve 15 by the fuel pressure in the pressure control chamber 18 and the spring force of the compression spring 18 is stronger than the force of raising the needle valve 15 by the fuel pressure in the nozzle chamber 17. Therefore, the needle valve 15 is lowered, and as a result, the needle valve 15 is closed, so that fuel injection from the nozzle 16 is stopped.

一方、このとき通路開閉弁３１の圧力制御室３６内、ばね室３８内およびピストン室４０内は全て第２のコモンレール３内の燃料圧（第２コモンレール圧と称する）となっており、従って弁体３５は図１に示されるように圧縮ばね３９のばね力によって上昇した位置にある。このとき、弁体３５は閉弁しており、弁体３５によって燃料流通通路３０ａと３０ｂ間の連通は遮断されている。このようにこのとき弁体３５が閉弁しているので増圧器１３の中間室２７内は第２コモンレール圧になっており、増圧器１３の高圧室２６も第２コモンレール圧となっている。これに対し、増圧器１３の増圧室３２は第１コモンレール圧となっているが通常運転時には第１コモンレール圧と第２コモンレール圧はほぼ等しく、従ってこのとき増圧ピストン２５は図１に示されるように圧縮ばね２８のばね力によって上昇した位置に保持される。   On the other hand, at this time, the pressure in the pressure control chamber 36, the spring chamber 38, and the piston chamber 40 of the passage opening / closing valve 31 are all at the fuel pressure in the second common rail 3 (referred to as the second common rail pressure). The body 35 is in a position raised by the spring force of the compression spring 39 as shown in FIG. At this time, the valve body 35 is closed, and the communication between the fuel flow passages 30a and 30b is blocked by the valve body 35. Thus, since the valve body 35 is closed at this time, the intermediate chamber 27 of the pressure intensifier 13 has the second common rail pressure, and the high pressure chamber 26 of the pressure intensifier 13 has the second common rail pressure. On the other hand, the pressure increasing chamber 32 of the pressure booster 13 has the first common rail pressure, but the first common rail pressure and the second common rail pressure are substantially equal during normal operation. Therefore, at this time, the pressure increasing piston 25 is shown in FIG. In this way, it is held at the raised position by the spring force of the compression spring 28.

一方、三方弁１４による通路切換作用によって燃料流通通路２０が燃料排出通路４３に連結されるとノズル部１２の圧力制御室１８内の燃料圧が低下するためにニードル弁１５が上昇し、その結果ニードル弁１５が開弁してノズル室１７内の燃料が噴口１６から噴射される。一方、このとき通路開閉弁３１のピストン室４０内の燃料は逆止弁４２を介して燃料流通通路３０ａ内に流出し、その結果ピストン室４０内の燃料圧は急速に低下する。ピストン室４０内の燃料圧が低下すると、このとき圧力制御室３６内に作用している第２コモンレール圧が圧縮ばね３９のばね力から定まる開弁圧よりも高ければ弁体３５が下降し、その結果燃料流通通路３０ａと３０ｂとが弁体３５の連通孔３４を介して連通せしめられる。即ち、弁体３５が開弁する。   On the other hand, when the fuel flow passage 20 is connected to the fuel discharge passage 43 by the passage switching action by the three-way valve 14, the fuel pressure in the pressure control chamber 18 of the nozzle portion 12 is lowered, so that the needle valve 15 is raised. The needle valve 15 is opened and the fuel in the nozzle chamber 17 is injected from the nozzle 16. On the other hand, at this time, the fuel in the piston chamber 40 of the passage opening / closing valve 31 flows out into the fuel circulation passage 30a via the check valve 42, and as a result, the fuel pressure in the piston chamber 40 rapidly decreases. When the fuel pressure in the piston chamber 40 decreases, the valve body 35 descends if the second common rail pressure acting in the pressure control chamber 36 at this time is higher than the valve opening pressure determined from the spring force of the compression spring 39, As a result, the fuel flow passages 30a and 30b are communicated with each other through the communication hole 34 of the valve body 35. That is, the valve body 35 is opened.

弁体３５が開弁すると増圧器１３の中間室２７内の燃料が通路開閉弁３１を通って燃料排出通路４３に排出される。従って中間室２７内の燃料圧が低下するために増圧ピストン２５には下向きの大きな力が作用し、その結果増圧室３２内の燃料圧は第１コモンレール圧よりも高くなる。従ってこのとき、燃料流通通路２１を介して増圧室３２内に連結されているノズル室１７内の燃料圧も第１コモンレール圧よりも高くなり、燃料噴射が行われている間、この高い燃料圧に維持される。従ってニードル弁１５が開弁すると噴口１６から第１コモンレール圧よりも高い噴射圧でもって燃料が噴射されることになる。   When the valve body 35 is opened, the fuel in the intermediate chamber 27 of the pressure intensifier 13 is discharged to the fuel discharge passage 43 through the passage opening / closing valve 31. Accordingly, since the fuel pressure in the intermediate chamber 27 decreases, a large downward force acts on the pressure-increasing piston 25. As a result, the fuel pressure in the pressure-increasing chamber 32 becomes higher than the first common rail pressure. Therefore, at this time, the fuel pressure in the nozzle chamber 17 connected to the pressure increasing chamber 32 via the fuel circulation passage 21 is also higher than the first common rail pressure, and this high fuel is being consumed during fuel injection. Maintained at pressure. Therefore, when the needle valve 15 is opened, fuel is injected from the nozzle 16 with an injection pressure higher than the first common rail pressure.

次いで三方弁１４による燃料通路切換作用により図１に示される如く燃料流通通路２０が再び高圧燃料供給通路１０に連結されると、ノズル部１２の圧力制御室１８内は第１コモンレール圧となり、その結果燃料の噴射が停止される。また、このとき増圧器１３の中間室２７内は徐々に第２コモンレール圧となり、増圧室３２内は第１コモンレール圧となって増圧ピストン２５は圧縮ばね２８のばね力によって再び図１に示されるような上昇した状態に保持される。また、通路開閉弁３１のピストン室４０内も徐々に第２コモンレール圧になるために図１に示されるように弁体３５が上昇し、通路開閉弁３１が再び閉弁する。   Next, when the fuel flow passage 20 is again connected to the high pressure fuel supply passage 10 as shown in FIG. 1 by the fuel passage switching action by the three-way valve 14, the pressure control chamber 18 of the nozzle portion 12 becomes the first common rail pressure, As a result, fuel injection is stopped. At this time, the pressure in the intermediate chamber 27 of the pressure booster 13 gradually becomes the second common rail pressure, the pressure in the pressure increase chamber 32 becomes the first common rail pressure, and the pressure increasing piston 25 is returned to FIG. It is held in the raised state as shown. Further, since the piston chamber 40 of the passage opening / closing valve 31 gradually becomes the second common rail pressure, the valve body 35 rises as shown in FIG. 1, and the passage opening / closing valve 31 is closed again.

次に機関始動時における噴射制御について説明する。前述したように機関始動後、第１のコモンレール２内の燃料圧が予め定められた設定圧に達する前は調圧弁５は閉弁している。このときには第２コモンレール圧は低く、その結果通路開閉弁３１は閉弁状態に保持される。従って燃料噴射時に中間室２７内の燃料が排出されることがなく、斯くして増圧ピストン２５による燃料噴射圧の増大作用は行われない。この間は、燃料噴射弁１から第１のコモンレール２内の燃料が噴射され、このときの燃料噴射圧は第１コモンレール圧とされる。   Next, injection control at the time of engine start will be described. As described above, after the engine is started, the pressure regulating valve 5 is closed before the fuel pressure in the first common rail 2 reaches a predetermined set pressure. At this time, the second common rail pressure is low, and as a result, the passage opening / closing valve 31 is held in the closed state. Accordingly, the fuel in the intermediate chamber 27 is not discharged at the time of fuel injection, and thus the fuel injection pressure is not increased by the pressure-increasing piston 25. During this time, the fuel in the first common rail 2 is injected from the fuel injection valve 1, and the fuel injection pressure at this time is the first common rail pressure.

一方、前述したように第１のコモンレール２内の燃料圧が予め定められた設定圧を越えると調圧弁５が開弁する。この場合、通路開閉弁３１の開弁圧をこの設定圧と同じか又はこの設定圧よりも低く設定しておくと調圧弁５が開弁したときに増圧ピストン２５による増圧作用が可能となり、通路開閉弁３１の開弁圧をこの設定圧よりも高く設定しておくと第２コモンレール圧が通路開閉弁３１の開弁圧よりも高くなった後に増圧ピストン２５による増圧作用が可能となる。   On the other hand, as described above, when the fuel pressure in the first common rail 2 exceeds a predetermined set pressure, the pressure regulating valve 5 is opened. In this case, if the valve opening pressure of the passage opening / closing valve 31 is set equal to or lower than the set pressure, the pressure increasing piston 25 can increase the pressure when the pressure regulating valve 5 is opened. If the valve opening pressure of the passage opening / closing valve 31 is set higher than the set pressure, the pressure increasing piston 25 can increase the pressure after the second common rail pressure becomes higher than the valve opening pressure of the passage opening / closing valve 31. It becomes.

このように本発明によれば、機関始動時には第１のコモンレール２と第２のコモンレール３の連通を遮断して高圧燃料ポンプ９から第１のコモンレール２のみに高圧の燃料を供給すると共に増圧ピストン２５の作動が停止される。一方、機関始動後暫らくして第２のコモンレール３の燃料圧も上昇すべきであると判断されたときには高圧燃料ポンプ９から第２のコモンレール３にも高圧の燃料を供給すると共に必要に応じて増圧ピストン２５が作動せしめられる。   As described above, according to the present invention, when the engine is started, the communication between the first common rail 2 and the second common rail 3 is cut off, and high pressure fuel is supplied from the high pressure fuel pump 9 only to the first common rail 2 and the pressure is increased. The operation of the piston 25 is stopped. On the other hand, when it is determined that the fuel pressure of the second common rail 3 should be increased for a while after the engine is started, high-pressure fuel is supplied from the high-pressure fuel pump 9 to the second common rail 3 as needed. Thus, the pressure increasing piston 25 is actuated.

増圧ピストン２５による増圧作用を行うときには第１のコモンレール２および第２のコモンレール３の双方の燃料が使用される。即ち、このときにはコモンレールの容積が増大したような形となるので燃料噴射および増圧ピストン２５による増圧作用が行われても第１および第２のコモンレール２，３内の燃料圧はさほど低下せず、斯くして燃料噴射圧を十分に高めることができる。一方、機関始動時には容積が小さい方のコモンレール２のみの燃料圧を上昇させるようにしているので短時間のうちに燃料圧を高めることができ、斯くして機関の良好な始動を確保することができる。   When the pressure-increasing action by the pressure-increasing piston 25 is performed, the fuel of both the first common rail 2 and the second common rail 3 is used. That is, at this time, since the volume of the common rail is increased, the fuel pressure in the first and second common rails 2 and 3 is greatly reduced even if the fuel injection and the pressure increasing action by the pressure increasing piston 25 are performed. Therefore, the fuel injection pressure can be sufficiently increased. On the other hand, when the engine is started, the fuel pressure of only the common rail 2 having the smaller volume is increased, so that the fuel pressure can be increased in a short time, and thus a good start of the engine can be ensured. it can.

図２に第２実施例を示す。この実施例では図１に示す実施例と異なって増圧器１３の中間室２７は第２のコモンレール３に連結されておらず、燃料流通通路３０ｂ、通路開閉弁３１および燃料流通通路３０ａを介して燃料流通通路２０のみに連結されている。また、この実施例では図１に示す実施例とは異なって通路開閉弁３１のばね室３８およびピストン室４０は共に燃料タンク８内に連結されている。従ってこの実施例では圧力制御室３６内に作用している第２コモンレール圧が圧縮ばね３９のばね力に定まる開弁圧よりも低いときには図１に示される実施例と同様に通路開閉弁３１は閉弁状態に保持される。   FIG. 2 shows a second embodiment. In this embodiment, unlike the embodiment shown in FIG. 1, the intermediate chamber 27 of the pressure booster 13 is not connected to the second common rail 3, and is connected via the fuel circulation passage 30b, the passage opening / closing valve 31 and the fuel circulation passage 30a. It is connected only to the fuel flow passage 20. Further, in this embodiment, unlike the embodiment shown in FIG. 1, the spring chamber 38 and the piston chamber 40 of the passage opening / closing valve 31 are both connected to the fuel tank 8. Therefore, in this embodiment, when the second common rail pressure acting in the pressure control chamber 36 is lower than the valve opening pressure determined by the spring force of the compression spring 39, the passage opening / closing valve 31 is the same as in the embodiment shown in FIG. The valve is kept closed.

一方、この実施例では圧力制御室３６内に作用している第２コモンレール圧が開弁圧よりも高くなると図１に示される実施例とは異なって通路開閉弁３１は開弁状態に保持される。従ってこの実施例ではこのように通路開閉弁３１が開弁状態に保持されているときに図２に示される如く燃料流通通路２０が高圧燃料供給通路１０に連結されると中間室２７内は第１コモンレール圧となる。次いで三方弁１４の燃料通路切換作用によって燃料流通通路２０が燃料排出通路４３に連結されると中間室２７内の燃料が排出され、増圧ピストン２５による増圧作用が行われる。   On the other hand, in this embodiment, when the second common rail pressure acting in the pressure control chamber 36 becomes higher than the valve opening pressure, the passage opening / closing valve 31 is held in an open state, unlike the embodiment shown in FIG. The Therefore, in this embodiment, when the fuel circulation passage 20 is connected to the high-pressure fuel supply passage 10 as shown in FIG. 1 common rail pressure. Next, when the fuel flow passage 20 is connected to the fuel discharge passage 43 by the fuel passage switching action of the three-way valve 14, the fuel in the intermediate chamber 27 is discharged, and the pressure increasing action by the pressure increasing piston 25 is performed.

図３に第３実施例を示す。この実施例では図１に示される調圧弁５に代えて、第１のコモンレール２と第２のコモンレール３とを連通したときに第１コモンレール圧と第２コモンレール圧とを等しくしうる連通制御弁５が用いられている。即ち、図３に示される連通制御弁５はピストン５０と、ピストン５０に連結されかつ連通孔５１を形成した弁体５２とを具備する。弁体５２と反対側のピストン５０の端面上には圧力制御室５３が形成され、この圧力制御室５３は第１のコモンレール２に連結される。一方、ピストン５０と反対側の弁体５２の端面上にはばね室５４が形成され、このばね室５４内には弁体５２を上方に向けて付勢する圧縮ばね５５が挿入される。また、弁体５２側のピストン５０の端面上にはピストン室５６が形成される。ばね室５４およびピストン室５６は燃料タンク８に連結される。   FIG. 3 shows a third embodiment. In this embodiment, instead of the pressure regulating valve 5 shown in FIG. 1, a communication control valve capable of equalizing the first common rail pressure and the second common rail pressure when the first common rail 2 and the second common rail 3 are communicated. 5 is used. That is, the communication control valve 5 shown in FIG. 3 includes a piston 50 and a valve body 52 connected to the piston 50 and having a communication hole 51. A pressure control chamber 53 is formed on the end surface of the piston 50 opposite to the valve body 52, and the pressure control chamber 53 is connected to the first common rail 2. On the other hand, a spring chamber 54 is formed on the end surface of the valve body 52 opposite to the piston 50, and a compression spring 55 is inserted into the spring chamber 54 to urge the valve body 52 upward. A piston chamber 56 is formed on the end face of the piston 50 on the valve body 52 side. The spring chamber 54 and the piston chamber 56 are connected to the fuel tank 8.

この実施例では圧力制御室５３内に作用している第１コモンレール圧が圧縮ばね５５のばね力に定まる開弁圧よりも低いときには連通制御弁５は閉弁状態に保持される。これに対し、圧力制御室５３内に作用している第１コモンレール圧が開弁圧よりも高くなると連通制御弁５は開弁状態に保持され、第１のコモンレール２と第２のコモンレール３とは連通孔５１を介して互に連通せしめられる。   In this embodiment, when the first common rail pressure acting in the pressure control chamber 53 is lower than the valve opening pressure determined by the spring force of the compression spring 55, the communication control valve 5 is held in the closed state. On the other hand, when the first common rail pressure acting in the pressure control chamber 53 becomes higher than the valve opening pressure, the communication control valve 5 is held in the valve open state, and the first common rail 2 and the second common rail 3 Are communicated with each other through the communication hole 51.

図４に第４実施例を示す。この実施例と図３に示す実施例と異なるところは、この第４実施例では連通制御弁５の弁体５２に第１のコモンレール２と第２のコモンレール３とを連通させるための連通孔５１に加えて更に別の連通孔５７が形成されていることである。また、この第４実施例では図３に示す実施例と異なって増圧器１３の中間室２７は第２のコモンレール３に連結されておらず、燃料流通通路３０ｂ、連通制御弁５および燃料流通通路３０ａを介して燃料流通通路２０のみに連結されている。   FIG. 4 shows a fourth embodiment. The difference between this embodiment and the embodiment shown in FIG. 3 is that in this fourth embodiment, a communication hole 51 for communicating the first common rail 2 and the second common rail 3 with the valve body 52 of the communication control valve 5. In addition to this, another communication hole 57 is formed. Further, in the fourth embodiment, unlike the embodiment shown in FIG. 3, the intermediate chamber 27 of the pressure intensifier 13 is not connected to the second common rail 3, and the fuel flow passage 30b, the communication control valve 5, and the fuel flow passage. It is connected only to the fuel flow passage 20 through 30a.

この実施例では圧力制御室５３内に作用している第１コモンレール圧が圧縮ばね５５のばね力に定まる開弁圧よりも低いときには連通制御弁５は閉弁状態に保持される。即ち、このときには連通路５１による第１のコモンレール２と第２のコモンレール３との連通は遮断されており、連通孔５７による燃料流通通路２０と中間室２７との連通も遮断されている。   In this embodiment, when the first common rail pressure acting in the pressure control chamber 53 is lower than the valve opening pressure determined by the spring force of the compression spring 55, the communication control valve 5 is held in the closed state. That is, at this time, the communication between the first common rail 2 and the second common rail 3 through the communication passage 51 is blocked, and the communication between the fuel flow passage 20 and the intermediate chamber 27 through the communication hole 57 is also blocked.

一方、圧力制御室５３内に作用している第１コモンレール圧が開弁圧よりも高くなると連通制御弁５は開弁状態に保持される。即ち、第１のコモンレール２と第２のコモンレール３は連通孔５１を介して互いに連通せしめられ、同時に中間室２７は連通孔５７を介して燃料流通通路２０に連通せしめられる。従ってこのとき増圧ピストン２５による増圧作用が行われる。このようにこの実施例では連通制御弁５が通路開閉弁３１の機能も有している。   On the other hand, when the first common rail pressure acting in the pressure control chamber 53 becomes higher than the valve opening pressure, the communication control valve 5 is held in the valve open state. That is, the first common rail 2 and the second common rail 3 are communicated with each other via the communication hole 51, and at the same time, the intermediate chamber 27 is communicated with the fuel circulation passage 20 via the communication hole 57. Accordingly, at this time, the pressure increasing action by the pressure increasing piston 25 is performed. Thus, in this embodiment, the communication control valve 5 also has the function of the passage opening / closing valve 31.

図５に第５実施例を示す。この実施例ではコモンレール連通路４内に図３に示す連通制御弁５と同じ構造の連通制御弁５が配置されているがこの第５実施例では圧力制御室５３が電磁ソレノイド或いはピエゾ圧電素子のようなアクチュエータによって駆動される三方弁６０によって第１のコモンレール２又は燃料タンク８に選択的に連結される。この実施例では三方弁６０の切換作用によって圧力制御室５３が第１のコモンレール２に連結されると連通制御弁５が開弁し、第１のコモンレール２と第２のコモンレール３とが連通孔５１を介して連通せしめられる。即ち、この実施例では第２のコモンレール３の燃料圧を上昇すべきであると判断されたときにはいつでも三方弁６０を切換えることによって第２のコモンレール３の燃料圧の昇圧作用を開始させることができる。   FIG. 5 shows a fifth embodiment. In this embodiment, a communication control valve 5 having the same structure as that of the communication control valve 5 shown in FIG. 3 is arranged in the common rail communication passage 4, but in this fifth embodiment, the pressure control chamber 53 is an electromagnetic solenoid or a piezoelectric element. The first common rail 2 or the fuel tank 8 is selectively connected by a three-way valve 60 driven by such an actuator. In this embodiment, when the pressure control chamber 53 is connected to the first common rail 2 by the switching action of the three-way valve 60, the communication control valve 5 is opened, and the first common rail 2 and the second common rail 3 are connected to the communication hole. Communicating via 51. That is, in this embodiment, when it is determined that the fuel pressure of the second common rail 3 should be increased, the boosting action of the fuel pressure of the second common rail 3 can be started by switching the three-way valve 60 whenever it is determined. .

図６に第６実施例を示す。この実施例ではニードル弁１５の圧力制御室１８および増圧ピストン２５の中間室２７が三位置切替弁７０を介して第１のコモンレール２および燃料排出通路４３のいずれか一方に選択的に連結される。また、この実施例では増圧器１３の中間室２７は第２のコモンレール３に連結されておらず、燃料流通通路３０を介して三位置切替弁７０のみに連結されている。   FIG. 6 shows a sixth embodiment. In this embodiment, the pressure control chamber 18 of the needle valve 15 and the intermediate chamber 27 of the pressure increasing piston 25 are selectively connected to one of the first common rail 2 and the fuel discharge passage 43 via a three-position switching valve 70. The In this embodiment, the intermediate chamber 27 of the pressure intensifier 13 is not connected to the second common rail 3 but is connected only to the three-position switching valve 70 via the fuel flow passage 30.

この三位置切替弁７０はニードル弁１５の圧力制御室１８および増圧ピストン２５の中間室２７を共に第１のコモンレール２に連結する位置と、ニードル弁１５の圧力制御室１８および増圧ピストン２５の中間室２７を共に燃料排出通路４３に連結する位置と、ニードル弁１５の圧力制御室１８のみを燃料排出通路４３に連結する位置との三つの位置をとる。   The three-position switching valve 70 includes a position where the pressure control chamber 18 of the needle valve 15 and the intermediate chamber 27 of the pressure increasing piston 25 are both connected to the first common rail 2, and the pressure control chamber 18 and the pressure increasing piston 25 of the needle valve 15. The intermediate chamber 27 is connected to the fuel discharge passage 43 together with the position where only the pressure control chamber 18 of the needle valve 15 is connected to the fuel discharge passage 43.

三位置切替弁７０の切替作用によってニードル弁１５の圧力制御室１８および増圧ピストン２５の中間室２７が第１のコモンレール２に連結されたときにはニードル弁１５が閉弁して燃料噴射が停止され、中間室２７内には第１コモンレール圧となる。一方、三位置切替弁７０の切替作用によってニードル弁１５の圧力制御室１８および増圧ピストン２５の中間室２７が共に燃料排出通路４３に連結されたときにはニードル弁１５が開弁して燃料噴射が行われると共に増圧ピストン２５が作動して燃料噴射圧が増大せしめられる。これに対し、三位置切替弁７０の切替作用によってニードル弁１５の圧力制御室１８のみが燃料排出通路４３に連結されたときには増圧ピストン２５が作動することなくニードル弁１５が開弁して燃料噴射が行われる。   When the pressure control chamber 18 of the needle valve 15 and the intermediate chamber 27 of the pressure increasing piston 25 are connected to the first common rail 2 by the switching action of the three-position switching valve 70, the needle valve 15 is closed and fuel injection is stopped. The intermediate chamber 27 has a first common rail pressure. On the other hand, when both the pressure control chamber 18 of the needle valve 15 and the intermediate chamber 27 of the pressure increasing piston 25 are connected to the fuel discharge passage 43 by the switching action of the three-position switching valve 70, the needle valve 15 opens and fuel injection is performed. At the same time, the pressure-increasing piston 25 is actuated to increase the fuel injection pressure. On the other hand, when only the pressure control chamber 18 of the needle valve 15 is connected to the fuel discharge passage 43 by the switching action of the three-position switching valve 70, the needle valve 15 is opened without operating the pressure increasing piston 25 and the fuel is discharged. Injection is performed.

本発明による燃料噴射装置の第１実施例を示す全体図である。1 is an overall view showing a first embodiment of a fuel injection device according to the present invention. 本発明による燃料噴射装置の第２実施例を示す全体図である。It is a general view which shows 2nd Example of the fuel-injection apparatus by this invention. 本発明による燃料噴射装置の第３実施例を示す全体図である。It is a general view which shows 3rd Example of the fuel-injection apparatus by this invention. 本発明による燃料噴射装置の第４実施例を示す全体図である。It is a general view which shows 4th Example of the fuel-injection apparatus by this invention. 本発明による燃料噴射装置の第５実施例を示す全体図である。It is a general view which shows 5th Example of the fuel-injection apparatus by this invention. 本発明による燃料噴射装置の第６実施例を示す全体図である。It is a general view which shows 6th Example of the fuel-injection apparatus by this invention.

符号の説明Explanation of symbols

１ 燃料噴射弁
２ 第１のコモンレール
３ 第２のコモンレール
５ 連通制御弁
１０ 高圧燃料供給通路
１２ ノズル部
１３ 増圧器
１４ 三方弁
１５ ニードル弁
１８ 圧力制御室
２５ 増圧ピストン
２７ 中間室
３１ 通路開閉弁
４３ 燃料排出通路 DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 1st common rail 3 2nd common rail 5 Communication control valve 10 High-pressure fuel supply passage 12 Nozzle part 13 Intensifier 14 Three-way valve 15 Needle valve 18 Pressure control chamber 25 Pressure increase piston 27 Intermediate | middle chamber 31 Passage opening / closing valve 43 Fuel discharge passage

Claims (7)

コモンレールに連結された燃料噴射弁を具備し、該燃料噴射弁が燃料噴射圧を増大するための増圧ピストンを備えており、コモンレールから増圧ピストンの中間室に導びかれた高圧の燃料を該中間室から排出させることにより燃料噴射圧の増大作用が行われる燃料噴射装置において、コモンレールを互いに分離された第１のコモンレールと第２のコモンレールから構成し、機関始動時には第１のコモンレールと第２のコモンレールの連通を遮断して燃料ポンプから第１のコモンレールのみに高圧の燃料を供給すると共に、機関始動後暫らくして第２のコモンレールの燃料圧も上昇すべきであると判断されたときには燃料ポンプから第２のコモンレールにも高圧の燃料を供給し、燃料噴射弁のニードル弁の圧力制御室および増圧ピストンの中間室が二位置切替弁を介して第１のコモンレールおよび燃料排出通路のいずれか一方に選択的に連結され、該中間室と二位置切替弁間に通路開閉弁が配置され、二位置切替弁の切替作用によってニードル弁の圧力制御室が第１のコモンレールに連結されたときにはニードル弁が閉弁して燃料噴射が停止されると共に該圧力制御室が燃料排出通路に連結されたときにはニードル弁が開弁して燃料噴射が行われ、二位置切替弁の切替作用によって増圧ピストンの中間室が燃料排出通路に連結されたときに上記通路開閉弁が閉弁していれば増圧ピストンの作動が停止され、このとき上記通路開閉弁が開弁していれば該中間室内の高圧の燃料が燃料排出通路内に排出されて増圧ピストンが作動せしめられる燃料噴射装置。 A fuel injection valve connected to the common rail, the fuel injection valve having a pressure increasing piston for increasing the fuel injection pressure, and supplying high pressure fuel led from the common rail to the intermediate chamber of the pressure increasing piston; In the fuel injection device in which the fuel injection pressure is increased by being discharged from the intermediate chamber, the common rail is composed of a first common rail and a second common rail which are separated from each other. It was determined that the communication of the second common rail was cut off and high pressure fuel was supplied only from the fuel pump to the first common rail, and that the fuel pressure of the second common rail should be increased for a while after the engine was started. sometimes the pressure supply of fuel to the second common rail from the fuel pump, an intermediate pressure control chamber and the pressure intensifying piston of the needle valve of the fuel injection valve Is selectively connected to one of the first common rail and the fuel discharge passage via a two-position switching valve, and a passage opening / closing valve is disposed between the intermediate chamber and the two-position switching valve. When the pressure control chamber of the needle valve is connected to the first common rail by the action, the needle valve is closed to stop fuel injection, and when the pressure control chamber is connected to the fuel discharge passage, the needle valve is opened. If the passage open / close valve is closed when the intermediate chamber of the booster piston is connected to the fuel discharge passage by the switching action of the two-position selector valve, the operation of the booster piston is stopped. In this case, if the passage opening / closing valve is open at this time, the high pressure fuel in the intermediate chamber is discharged into the fuel discharge passage and the pressure increasing piston is operated . 第１のコモンレールは第１のコモンレールの燃料圧が予め定められた設定圧を越えたときに開弁する連通制御弁を介して第２のコモンレールに連通している請求項１に記載の燃料噴射装置。   2. The fuel injection according to claim 1, wherein the first common rail communicates with the second common rail via a communication control valve that opens when the fuel pressure of the first common rail exceeds a predetermined set pressure. apparatus. 第１のコモンレールは連通制御弁を介して第２のコモンレールに連通しており、機関始動後暫らくして第２のコモンレールの燃料圧も上昇すべきであると判断されたときに該連通制御弁が開弁せしめられる請求項１に記載の燃料噴射装置。   The first common rail communicates with the second common rail via a communication control valve, and the communication control is performed when it is determined that the fuel pressure of the second common rail should be increased for a while after the engine is started. The fuel injection device according to claim 1, wherein the valve is opened. 上記通路開閉弁は第２のコモンレールの燃料圧により駆動されて第２のコモンレールの燃料圧が予め定められた設定燃料圧よりも高くなったときに開弁する請求項１に記載の燃料噴射装置。 The fuel injection device according to claim 1 , wherein the passage opening / closing valve is driven by the fuel pressure of the second common rail and opens when the fuel pressure of the second common rail becomes higher than a predetermined set fuel pressure. . 第１のコモンレールと第２のコモンレール間に第１のコモンレールと第２のコモンレール間の連通を制御する連通制御弁が配置されており、該連通制御弁が上記通路開閉弁の機能も有している請求項１に記載の燃料噴射装置。 A communication control valve for controlling communication between the first common rail and the second common rail is disposed between the first common rail and the second common rail, and the communication control valve also has the function of the passage opening / closing valve. The fuel injection device according to claim 1 . 増圧ピストンの中間室が絞りを介して第２のコモンレールに連結されている請求項１に記載の燃料噴射装置。 The fuel injection device according to claim 1 , wherein the intermediate chamber of the boosting piston is connected to the second common rail via a throttle . コモンレールに連結された燃料噴射弁を具備し、該燃料噴射弁が燃料噴射圧を増大するための増圧ピストンを備えており、コモンレールから増圧ピストンの中間室に導びかれた高圧の燃料を該中間室から排出させることにより燃料噴射圧の増大作用が行われる燃料噴射装置において、コモンレールを互いに分離された第１のコモンレールと第２のコモンレールから構成し、機関始動時には第１のコモンレールと第２のコモンレールの連通を遮断して燃料ポンプから第１のコモンレールのみに高圧の燃料を供給すると共に、機関始動後暫らくして第２のコモンレールの燃料圧も上昇すべきであると判断されたときには燃料ポンプから第２のコモンレールにも高圧の燃料を供給し、燃料噴射弁のニードル弁の圧力制御室および増圧ピストンの中間室が三位置切替弁を介して第１のコモンレールおよび燃料排出通路のいずれか一方に選択的に連結され、三位置切替弁の切替作用によってニードル弁の圧力制御室が第１のコモンレールに連結されたときにはニードル弁が閉弁して燃料噴射が停止され、三位置切替弁の切替作用によってニードル弁の圧力制御室および増圧ピストンの中間室が共に燃料排出通路に連結されたときにはニードル弁が開弁して燃料噴射が行われると共に増圧ピストンが作動して燃料噴射圧が増大せしめられ、三位置切替弁の切替作用によってニードル弁の圧力制御室のみが燃料排出通路に連結されたときには増圧ピストンが作動することなくニードル弁が開弁して燃料噴射が行われる燃料噴射装置。 A fuel injection valve connected to the common rail, the fuel injection valve having a pressure increasing piston for increasing the fuel injection pressure, and supplying high pressure fuel led from the common rail to the intermediate chamber of the pressure increasing piston; In the fuel injection device in which the fuel injection pressure is increased by being discharged from the intermediate chamber, the common rail is composed of a first common rail and a second common rail which are separated from each other. It was determined that the communication of the second common rail was cut off and high pressure fuel was supplied only from the fuel pump to the first common rail, and that the fuel pressure of the second common rail should be increased for a while after the engine was started. Sometimes high-pressure fuel is also supplied from the fuel pump to the second common rail, and the intermediate between the pressure control chamber of the needle valve of the fuel injection valve and the booster piston Is selectively connected to either the first common rail or the fuel discharge passage via the three-position switching valve, and the pressure control chamber of the needle valve is connected to the first common rail by the switching action of the three-position switching valve. Sometimes the needle valve is closed and fuel injection is stopped, and when the pressure control chamber of the needle valve and the intermediate chamber of the boosting piston are both connected to the fuel discharge passage by the switching action of the three-position switching valve, the needle valve is opened. When the fuel injection is performed and the pressure increasing piston is activated to increase the fuel injection pressure, and only the pressure control chamber of the needle valve is connected to the fuel discharge passage by the switching action of the three-position switching valve, the pressure increasing piston A fuel injection device in which a needle valve is opened and fuel injection is performed without operating .
JP2005047097A 2005-02-23 2005-02-23 Fuel injection device Expired - Fee Related JP4329704B2 (en)

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