EP1357283B1 - Fuel injection system for internal combustion engine - Google Patents

Fuel injection system for internal combustion engine Download PDF

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Publication number
EP1357283B1
EP1357283B1 EP03004643.7A EP03004643A EP1357283B1 EP 1357283 B1 EP1357283 B1 EP 1357283B1 EP 03004643 A EP03004643 A EP 03004643A EP 1357283 B1 EP1357283 B1 EP 1357283B1
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EP
European Patent Office
Prior art keywords
pump
pressure
fuel
suction valve
valve
Prior art date
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EP03004643.7A
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German (de)
French (fr)
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EP1357283A2 (en
EP1357283A3 (en
Inventor
Stefan Kieferle
Achim Koehler
Sascha Ambrock
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP1357283A3 publication Critical patent/EP1357283A3/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
    • F02M59/46—Valves
    • F02M59/464—Inlet valves of the check valve type
    • 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

Definitions

  • the invention relates to a fuel injection device for an internal combustion engine according to the preamble of claim 1.
  • Such a fuel injection device is characterized by the DE 198 48 035 A1 known.
  • This fuel injection device has a high-pressure pump which is provided for a common-rail injection system in which fuel is conveyed under high pressure into a reservoir by the high-pressure pump. With the memory arranged on the cylinders of the internal combustion engine injectors are connected.
  • a feed pump is provided in common rail injection systems, is conveyed by the fuel from a reservoir to the high pressure pump.
  • the high pressure pump has a plurality of pump elements, each with a working space limiting, driven in a stroke pump piston. It is provided in the working space opening a suction valve which opens during the suction stroke of the pump piston and flows through the fuel into the working space.
  • the suction valve has a valve member acted upon by a closing spring in a closing direction, the closing spring being supported on the pump piston. At the beginning of the suction stroke of the piston is compressed by this the closing spring most, so that the pressure at which the suction valve opens is higher than during the suction stroke of the pump piston, during which the closing spring is increasingly relaxed. Under certain operating conditions of the internal combustion engine, in particular in overrun, should be promoted by the high-pressure pump no fuel in the memory. To ensure this, the opening differential pressure of the suction valve is set relatively high, for example to at least 2 bar. However, this leads to the fact that the delivery rate of the high-pressure pump is not optimal.
  • a fuel injection device which comprises a high-pressure pump, in which the closing spring of the suction valve is supported at least indirectly on the pump piston.
  • a fuel injection device with a high-pressure pump which has a suction valve whose opening differential pressure is equal to or less than 0.9 bar.
  • the opening differential pressure of the suction valve is not dependent on the stroke of the pump piston, so that the specified value for the opening differential pressure is not transferable to a suction valve with depending on the stroke of the pump piston changing opening differential pressure, as there is not a single fixed value for the opening differential pressure present is.
  • the information in the DE 199 41 850 A1 thus do not give sufficient teaching for the determination of the opening differential pressure in a suction valve with depending on the stroke of the pump piston changing opening differential pressure.
  • the fuel injection device according to the invention with the features of claim 1 has the advantage that the minimum opening differential pressure of the suction valve is very low and thereby the delivery rate of the high-pressure pump is improved.
  • FIG. 1 a fuel injection device for an internal combustion engine of a motor vehicle in a schematic representation with a high-pressure pump
  • FIG. 2 one in FIG. 1 denoted by II Section of the high pressure pump in an enlarged view with a pump piston in a top dead center
  • FIG. 3 the cutout II with the pump piston in a bottom dead center.
  • FIG. 1 a fuel injection device for an internal combustion engine, for example of a motor vehicle is shown.
  • the internal combustion engine is preferably a self-igniting internal combustion engine and has one or more cylinders.
  • the fuel injection device has a feed pump 10, which is arranged for example in a fuel tank 12 of the motor vehicle, but can also be arranged outside of the container 12.
  • the feed pump 10 may have an electric drive motor and sucks, for example, via a pre-filter 14 fuel from the fuel tank 12 at.
  • the feed pump 10 can also be driven mechanically, for example, by the internal combustion engine.
  • a line 16 leads to a high-pressure pump 18.
  • a fuel filter 20 is arranged in the line 16, which is designed as a fine filter and which is flowed through by the funded by the feed pump 10 fuel.
  • the high-pressure pump 18 has, for example, a plurality of pump elements 22, each of which has a pump piston 26 guided in a cylinder bore 24, which is driven via an eccentric drive 28 in a stroke movement.
  • the high-pressure pump 18 is preferably driven mechanically by the internal combustion engine.
  • the funded by the high pressure pump 18 fuel is over a line 30 is supplied to a memory 32.
  • Each pump element 22 has a work space 34 bounded by the pump piston 26 into which an inlet from the feed pump 10 opens and from which a discharge to the accumulator 32 is discharged.
  • a suction valve 36 opening into the working space 34 is provided, and in the outlet of each pump element 22, a pressure valve 38 opening towards the reservoir 32 is provided.
  • an injector 40 For each cylinder of the internal combustion engine, an injector 40 is provided, is injected through the fuel into the combustion chamber of the cylinder. Each injector 40 is connected to the reservoir 32 via a conduit 42, and the opening of the fuel injector 40 is controlled by an electrically actuated valve 44 which is driven by an electronic controller 46. From the injectors 40, a return 41 to the fuel tank 12 can dissipate uninjected fuel.
  • a pressure valve 48 For controlling and / or limiting the pressure prevailing in the memory 32, a pressure valve 48 may be provided which opens when a predetermined pressure is exceeded and releases a return via a line 50 from the memory 32 into the fuel tank 12.
  • a pressure sensor 52 On the memory 32, a pressure sensor 52 is also arranged, through which the pressure in the memory 32 is detected and electrically connected to the Control device 46 is connected, which is thus supplied with a signal for the pressure prevailing in the memory 32.
  • a return 54 may be provided, via which, for example, a leakage amount of fuel can flow and which can open into the conduit 50.
  • a fuel metering device 60 is arranged, through which a flow area of the connection to the high pressure pump 18 is adjusted.
  • the fuel metering device 60 is actuated by the control device 46.
  • the fuel metering device 60 has a flow control valve 62 and an actuator 64, which is controlled by the control device 46.
  • the flow control valve 62 By means of the flow control valve 62, the flow area of the connection to the high pressure pump 18 can be adjusted continuously between zero and a maximum flow area.
  • actuator 64 an electromagnet or a piezoelectric actuator can be used, which is supplied in each case by the control device 46 with a defined electrical voltage and thereby brings the flow control valve 62 in a defined position in which this releases a defined flow area.
  • the controller 46 sets a desired pressure in the memory 32 specified.
  • the control device 46 receives a signal for the actual pressure in the memory 32.
  • the pressure in the memory 32 is dependent on the amount of fuel delivered by the high-pressure pump 18 into the accumulator 32.
  • the amount of fuel delivered by the high-pressure pump 18 can be changed by changing the flow area of the connection to the feed pump 10 by means of the fuel metering device 60.
  • the fuel metering device 60 is controlled by the control device 46 such that it sets in the connection to the feed pump 10, a flow area which is so large that the high-pressure pump 18 inflowing amount of fuel is so large that funded by the high-pressure pump 18 into the memory 32 Amount of fuel to maintain the predetermined target pressure in the memory 32 is sufficient. If the actual pressure in the accumulator 32 is less than the target pressure, then a too small amount of fuel is conveyed by the high-pressure pump 18 and the fuel metering device 60 is controlled by the control device so that it releases a larger flow area in the connection to the feed pump 10 and thus by the high pressure pump 18 delivered amount of fuel is increased.
  • the suction valve 36 of a pump element 22 is explained in more detail, wherein all pump elements 22 are identical.
  • an inlet channel 72 for the funded by the pump 10 fuel into the working space 34 is formed.
  • the working space 34 facing a valve seat 74 is formed, which is for example at least approximately conical.
  • the suction valve 36 has a valve member 76, which is formed for example in the form of a ball and which cooperates with the valve seat 74 for controlling the connection of the inlet channel 72 with the working space 34.
  • the valve member 76 is received, for example, in a pump member 26 towards the arranged support member 78.
  • the suction valve 36 also has a closing spring 80, which is formed for example as a helical compression spring and which is clamped between the pump piston 26 and the support member 78.
  • a closing spring 80 By the closing spring 80, the valve member 76 is pressed in the closing direction to the valve seat 74.
  • the valve member 76 is also acted upon by the pressure prevailing in the working space 34 in the closing direction.
  • the pump piston 26 has at its end facing the valve member 76 a reduced in diameter extension 82, wherein at the transition from the full diameter of the pump piston 26, where this is tightly guided in the cylinder bore 24 to the extension 82, an annular shoulder 84 is formed on the closing spring 80 is supported.
  • the closing spring 80 surrounds the extension 82 and the carrier part 78 is subsequently arranged on the extension 82.
  • the front end of the extension 82 of the pump piston 26 forms a stop for limiting the opening movement of the valve member 76 by the support member 78 comes to the extension 82 to the plant.
  • the closing spring 80 of the suction valve 36 is highly compressed and accordingly exerts a high force on the valve member 76, with which this is pressed against the valve seat 74.
  • the force generated by the closing spring 80 and by the pressure prevailing in the working space 34 on the valve member 76 counteracts the force generated in the inlet channel 72 pressure on the valve member 76 in the opening direction.
  • the valve member 76 moves against the force of the closing spring 80 in Opening direction and releases the mouth of the inlet channel 72 into the working space 34.
  • the pressure at which the valve member 76 moves in the opening direction is referred to as the opening differential pressure of the suction valve 36.
  • the pump piston 26 moves according to its top dead center FIG. 2 according to its bottom dead center according to FIG. 3 .
  • the closing spring 80 is increasingly relaxed, so that this causes a smaller force in the closing direction on the valve member 76 and corresponding to the opening differential pressure of the suction valve 36 is lower.
  • the opening differential pressure of the suction valve 36 is highest and will be referred to as maximum opening differential pressure hereinafter.
  • the opening differential pressure decreases.
  • a mean opening differential pressure of the suction valve 36 results.
  • the opening differential pressure of the suction valve 36 is the lowest, and is hereinafter referred to as the minimum opening differential pressure. It is envisaged that the minimum opening differential pressure of the suction valve 36 is less than 0.9 bar, preferably at most 0.8 bar.
  • the mean opening differential pressure and the maximum opening differential pressure of the suction valve 36 are then dependent on the spring rate c of the closing spring 80, that is, the change in the force generated by this force relative to the spring travel, and the stroke of the pump piston 26 between the top and bottom dead center.
  • the spring rate c of the closing spring 80 may have a small value, but the force exerted by the closing spring 80 on the valve member 76 substantially changes over the relatively large suction stroke of the pump piston 26.
  • the mean opening differential pressure of the suction valve 36 is greater than 0.9 bar.
  • the ratio between the average opening differential pressure and the minimum opening differential pressure of the suction valve 36 is greater than 1 and is at most about 10.
  • the influence of tolerances of the components of the high-pressure pump 18 can be reduced to the opening pressure and thus also an improvement of the uniform fuel delivery can be achieved by all pump elements 22.
  • the filling of the working space 34 can be improved, since the two filling decisive parameters, namely the filling effective pressure difference before and after the suction valve 36 and the opening duration of the suction valve 36, at low opening differential pressure of the suction valve 36 large are.
  • a delivery pump 10 with a lower delivery rate and a correspondingly smaller dimensioned drive can be used, which is less expensive. Characterized in that by means of the fuel metering device 60 of the Druchflußquerites from the feed pump 10 forth is completely closed, a zero promotion of the high-pressure pump 18 is ensured even at low opening differential pressure of the suction valve 36.

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einer Kraftstoffeinspritzeinrichtung für eine Brennkraftmaschine nach der Gattung des Anspruchs 1.The invention relates to a fuel injection device for an internal combustion engine according to the preamble of claim 1.

Eine solche Kraftstoffeinspritzeinrichtung ist durch die DE 198 48 035 A1 bekannt. Diese Kraftstoffeinspritzeinrichtung weist eine Hochdruckpumpe auf, die für ein Common-Rail-Einspritzsystem vorgesehen ist, bei dem durch die Hochdruckpumpe Kraftstoff unter Hochdruck in einen Speicher gefördert wird. Mit dem Speicher sind an den Zylindern der Brennkraftmaschine angeordnete Injektoren verbunden. Üblicherweise ist bei Common-Rail-Einspritzsystemen eine Förderpumpe vorgesehen, durch die Kraftstoff aus einem Vorratsbehälter zur Hochdruckpumpe gefördert wird. Die Hochdruckpumpe weist mehrere Pumpenelemente auf, mit jeweils einem einen Arbeitsraum begrenzenden, in einer Hubbewegung angetriebenen Pumpenkolben. Es ist ein in den Arbeitsraum öffnendes Saugventil vorgesehen, das beim Saughub des Pumpenkolbens öffnet und durch das Kraftstoff in den Arbeitsraum einströmt. Das Saugventil weist ein durch eine Schließfeder in einer Schließrichtung beaufschlagtes Ventilglied auf, wobei sich die Schließfeder am Pumpenkolben abstützt. Zu Beginn des Saughubs des Kolbens ist durch diesen die Schließfeder am stärksten komprimiert, so daß der Druck, bei dem das Saugventil öffnet höher ist als während des Saughubs des Pumpenkolbens, während dem die Schließfeder zunehmend entspannt wird. Unter bestimmten Betriebsbedingungen der Brennkraftmaschine, insbesondere im Schubbetrieb, soll durch die Hochdrückpumpe kein Kraftstoff in den Speicher gefördert werden. Um dies sicherzustellen, wird der Öffnungsdifferenzdruck des Saugventils relativ hoch eingestellt, beispielsweise auf mindestens 2 bar. Dies führt jedoch dazu, daß der Liefergrad der Hochdruckpumpe nicht optimal ist.Such a fuel injection device is characterized by the DE 198 48 035 A1 known. This fuel injection device has a high-pressure pump which is provided for a common-rail injection system in which fuel is conveyed under high pressure into a reservoir by the high-pressure pump. With the memory arranged on the cylinders of the internal combustion engine injectors are connected. Usually, a feed pump is provided in common rail injection systems, is conveyed by the fuel from a reservoir to the high pressure pump. The high pressure pump has a plurality of pump elements, each with a working space limiting, driven in a stroke pump piston. It is provided in the working space opening a suction valve which opens during the suction stroke of the pump piston and flows through the fuel into the working space. The suction valve has a valve member acted upon by a closing spring in a closing direction, the closing spring being supported on the pump piston. At the beginning of the suction stroke of the piston is compressed by this the closing spring most, so that the pressure at which the suction valve opens is higher than during the suction stroke of the pump piston, during which the closing spring is increasingly relaxed. Under certain operating conditions of the internal combustion engine, in particular in overrun, should be promoted by the high-pressure pump no fuel in the memory. To ensure this, the opening differential pressure of the suction valve is set relatively high, for example to at least 2 bar. However, this leads to the fact that the delivery rate of the high-pressure pump is not optimal.

Durch die WO 01/40657 A1 ist ebenfalls eine Kraftstoffeinspritzeinrichtung bekannt, die eine Hochdruckpumpe umfasst, bei der sich die Schließfeder des Saugventils zumindest mittelbar am Pumpenkolben abstützt.By the WO 01/40657 A1 a fuel injection device is also known which comprises a high-pressure pump, in which the closing spring of the suction valve is supported at least indirectly on the pump piston.

Durch die DE 199 41850 A1 ist eine Kraftstoffeinspritzeinrichtung mit einer Hochdruckpumpe bekannt, die ein Saugventil aufweist, dessen Öffnungsdifferenzdruck kleiner gleich 0,9 bar beträgt. Der Öffnungsdifferenzdruck des Saugventils ist dabei jedoch nicht vom Hub des Pumpenkolbens abhängig, so dass der angegebene Wert für den Öffnungsdifferenzdruck nicht auf ein Saugventil mit sich abhängig vom Hub des Pumpenkolbens änderndem Öffnungsdifferenzdruck übertragbar ist, da bei diesem nicht ein einziger fester Wert für den Öffnungsdifferenzdruck vorhanden ist. Die Angaben in der DE 199 41 850 A1 geben somit keine ausreichende Lehre für die Bestimmung des Öffnungsdifferenzdrucks bei einem Saugventil mit sich abhängig vom Hub des Pumpenkolbens änderndem Öffnungsdifferenzdruck.By the DE 199 41850 A1 a fuel injection device with a high-pressure pump is known which has a suction valve whose opening differential pressure is equal to or less than 0.9 bar. However, the opening differential pressure of the suction valve is not dependent on the stroke of the pump piston, so that the specified value for the opening differential pressure is not transferable to a suction valve with depending on the stroke of the pump piston changing opening differential pressure, as there is not a single fixed value for the opening differential pressure present is. The information in the DE 199 41 850 A1 thus do not give sufficient teaching for the determination of the opening differential pressure in a suction valve with depending on the stroke of the pump piston changing opening differential pressure.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Kraftstoffeinspritzeinrichtung mit den Merkmalen gemäß Anspruch 1 hat demgegenüber den Vorteil, daß der minimale Öffnungsdifferenzdruck des Saugventils sehr gering und dadurch der Liefergrad der Hochdruckpumpe verbessert ist.The fuel injection device according to the invention with the features of claim 1 has the advantage that the minimum opening differential pressure of the suction valve is very low and thereby the delivery rate of the high-pressure pump is improved.

In den abhängigen Ansprüchen sind vorteilhafte Ausgestaltungen und Weiterbildungen der erfindungsgemäßen Kraftstoffeinspritzeinrichtung angegeben. Die Ausbildung gemäß Anspruch 3 ermöglicht es, daß eine Nullförderung der Hochdruckpumpe bei geringem Öffnungsdifferenzdruck des Saugventils erreicht werden kann, indem der Durchflußquerschnitt durch die Kraftstoffzumeßeinrichtung vollständig verschlossen wird.In the dependent claims advantageous refinements and developments of the fuel injection device according to the invention are given. The embodiment according to claim 3 makes it possible that a zero delivery of the high-pressure pump can be achieved at low opening differential pressure of the suction valve by the flow area is completely closed by the fuel metering.

Zeichnungdrawing

Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Es zeigen Figur 1 eine Kraftstoffeinspritzeinrichtung für eine Brennkraftmaschine eines Kraftfahrzeugs in schematischer Darstellung mit einer Hochdruckpumpe, Figur 2 einen in Figur 1 mit II bezeichneten Ausschnitt der Hochdruckpumpe in vergrößerter Darstellung mit einem Pumpenkolben in einem oberen Totpunkt und Figur 3 den Ausschnitt II mit dem Pumpenkolben in einem unteren Totpunkt.An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. Show it FIG. 1 a fuel injection device for an internal combustion engine of a motor vehicle in a schematic representation with a high-pressure pump, FIG. 2 one in FIG. 1 denoted by II Section of the high pressure pump in an enlarged view with a pump piston in a top dead center and FIG. 3 the cutout II with the pump piston in a bottom dead center.

Beschreibung des AusführungsbeispielsDescription of the embodiment

In Figur 1 ist eine Kraftstoffeinspritzeinrichtung für eine Brennkraftmaschine beispielsweise eines Kraftfahrzeugs dargestellt. Die Brennkraftmaschine ist vorzugsweise eine selbstzündende Brennkraftmaschine und weist einen oder mehrere Zylinder auf. Die Kraftstoffeinspritzeinrichtung weist eine Förderpumpe 10 auf, die beispielsweise in einem Kraftstoffvorratsbehälter 12 des Kraftfahrzeugs angeordnet ist, jedoch auch außerhalb des Behälters 12 angeordnet sein kann. Die Förderpumpe 10 kann einen elektrischen Antriebsmotor aufweisen und saugt beispielsweise über ein Vorfilter 14 Kraftstoff aus dem Kraftstoffvorratsbehälter 12 an. Die Förderpumpe 10 kann auch beispielsweise mechanisch durch die Brennkraftmaschine angetrieben werden. Vom Auslass der Förderpumpe 10 führt eine Leitung 16 zu einer Hochdruckpumpe 18. Zwischen der Förderpumpe 10 und der Hochdruckpumpe 18 ist in der Leitung 16 ein Kraftstoffilter 20 angeordnet, das als Feinfilter ausgebildet ist und das von dem durch die Förderpumpe 10 geförderten Kraftstoff durchströmt wird.In FIG. 1 a fuel injection device for an internal combustion engine, for example of a motor vehicle is shown. The internal combustion engine is preferably a self-igniting internal combustion engine and has one or more cylinders. The fuel injection device has a feed pump 10, which is arranged for example in a fuel tank 12 of the motor vehicle, but can also be arranged outside of the container 12. The feed pump 10 may have an electric drive motor and sucks, for example, via a pre-filter 14 fuel from the fuel tank 12 at. The feed pump 10 can also be driven mechanically, for example, by the internal combustion engine. From the outlet of the feed pump 10, a line 16 leads to a high-pressure pump 18. Between the feed pump 10 and the high pressure pump 18, a fuel filter 20 is arranged in the line 16, which is designed as a fine filter and which is flowed through by the funded by the feed pump 10 fuel.

Die Hochdruckpumpe 18 weist beispielsweise mehrere Pumpenelemente 22 auf, die jeweils einen in einer Zylinderbohrung 24 geführten Pumpenkolben 26 aufweisen, der über einen Exzenterantrieb 28 in einer Hubbewegung angetrieben wird. Die Hochdruckpumpe 18 wird vorzugsweise mechanisch durch die Brennkraftmaschine angetrieben. Der durch die Hochdruckpumpe 18 geförderte Kraftstoff wird über eine Leitung 30 einem Speicher 32 zugeführt. Jedes Pumpenelement 22 weist einen vom Pumpenkolben 26 begrenzten Arbeitsraum 34 auf, in den ein Zulauf von der Förderpumpe 10 her mündet und von dem ein Ablauf zum Speicher 32 abführt. Im Zulauf jedes Pumpenelements 22 ist ein in den Arbeitsraum 34 öffnendes Saugventil 36 vorgesehen und im Ablauf jedes Pumpenelements 22 ist ein zum Speicher 32 hin öffnendes Druckventil 38 vorgesehen. Beim Saughub des Pumpenkolben 26, wenn dieser sich radial nach innen bewegt, öffnet das jeweilige Saugventil 36 und in den Arbeitsraum 34 strömt Kraftstoff von der Förderpumpe 10 ein, während das Druckventil 38 geschlossen ist. Beim Förderhub des Pumpenkolbens 26, wenn dieser sich radial nach außen bewegt, öffnet das jeweilige Druckventil 38 und aus dem Arbeitsraum 34 strömt Kraftstoff zum Speicher 32 hin ab, während das Saugventil 36 geschlossen ist.The high-pressure pump 18 has, for example, a plurality of pump elements 22, each of which has a pump piston 26 guided in a cylinder bore 24, which is driven via an eccentric drive 28 in a stroke movement. The high-pressure pump 18 is preferably driven mechanically by the internal combustion engine. The funded by the high pressure pump 18 fuel is over a line 30 is supplied to a memory 32. Each pump element 22 has a work space 34 bounded by the pump piston 26 into which an inlet from the feed pump 10 opens and from which a discharge to the accumulator 32 is discharged. In the inlet of each pump element 22, a suction valve 36 opening into the working space 34 is provided, and in the outlet of each pump element 22, a pressure valve 38 opening towards the reservoir 32 is provided. During the suction stroke of the pump piston 26, when it moves radially inward, opens the respective suction valve 36 and into the working space 34, fuel flows from the feed pump 10, while the pressure valve 38 is closed. During the delivery stroke of the pump piston 26, when it moves radially outward, opens the respective pressure valve 38 and from the working space 34, fuel flows to the memory 32 out while the suction valve 36 is closed.

Für jeden Zylinder der Brennkraftmaschine ist ein Injektor 40 vorgesehen, durch den Kraftstoff in den Brennraum des Zylinders eingespritzt wird. Jeder Injektor 40 ist über eine Leitung 42 mit dem Speicher 32 verbunden und die Öffnung des Injektors 40 zur Kraftstoffeinspritzung wird durch ein elektrisch angesteuertes Ventil 44 gesteuert, das von einer elektronischen Steuereinrichtung 46 angesteuert wird. Von den Injektoren 40 kann ein Rücklauf 41 zum Kraftstoffvorratsbehälter 12 abführen für nicht eingespritzten Kraftstoff.For each cylinder of the internal combustion engine, an injector 40 is provided, is injected through the fuel into the combustion chamber of the cylinder. Each injector 40 is connected to the reservoir 32 via a conduit 42, and the opening of the fuel injector 40 is controlled by an electrically actuated valve 44 which is driven by an electronic controller 46. From the injectors 40, a return 41 to the fuel tank 12 can dissipate uninjected fuel.

Zur Steuerung und/oder Begrenzung des im Speicher 32 herrschenden Drucks kann ein Druckventil 48 vorgesehen sein, das bei Überschreiten eines vorgegeben Drucks öffnet und einen Rücklauf über eine Leitung 50 vom Speicher 32 in den Kraftstoffvorratsbehälter 12 freigibt. Am Speicher 32 ist außerdem ein Drucksensor 52 angeordnet, durch den der Druck im Speicher 32 erfasst wird und der elektrisch mit der Steuereinrichtung 46 verbunden ist, der somit ein Signal für den im Speicher 32 herrschenden Druck zugeführt wird. An der Hochdruckpumpe 18 kann ein Rücklauf 54 vorgesehen sein, über den beispielsweise eine Leckmenge an Kraftstoff abfließen kann und der in die Leitung 50 münden kann.For controlling and / or limiting the pressure prevailing in the memory 32, a pressure valve 48 may be provided which opens when a predetermined pressure is exceeded and releases a return via a line 50 from the memory 32 into the fuel tank 12. On the memory 32, a pressure sensor 52 is also arranged, through which the pressure in the memory 32 is detected and electrically connected to the Control device 46 is connected, which is thus supplied with a signal for the pressure prevailing in the memory 32. At the high pressure pump 18, a return 54 may be provided, via which, for example, a leakage amount of fuel can flow and which can open into the conduit 50.

In der Verbindung zwischen der Förderpumpe 10 und der Hochdruckpumpe 18 ist eine Kraftstoffzumeßeinrichtung 60 angeordnet, durch die ein Durchflußquerschnitt der Verbindung zur Hochdruckpumpe 18 eingestellt wird. Die Kraftstoffzumeßeinrichtung 60 wird durch die Steuereinrichtung 46 angesteuert. Die Kraftstoffzumeßeinrichtung 60 weist ein Durchflußregelventil 62 auf und einen Aktor 64, der durch die Steuereinrichtung 46 angesteuert wird. Mittels des Durchflußregelventils 62 kann der Durchflußquerschnitt der Verbindung zur Hochdruckpumpe 18 kontinuierlich verstellt werden zwischen Null und einem maximalen Durchflußquerschnitt. Als Aktor 64 kann ein Elektromagnet oder ein Piezoaktor verwendet werden, der jeweils durch die Steuereinrichtung 46 mit einer definierten elektrischen Spannung versorgt wird und dabei das Durchflußregelventil 62 in eine definierte Stellung bringt, in der dieses einen definierten Durchflußquerschnitt freigibt. Unter bestimmten Betriebsbedingungen der Brennkraftmaschine, insbesondere im Schubbetrieb, darf durch die Hochdruckpumpe 18 kein Kraftstoff in den Speicher 32 gefördert werden. Hierzu wird durch die Kraftstoffzumeßeinrichtung 60 der Durchflußquerschnitt von der Förderpumpe 10 zur Hochdruckpumpe 18 vollständig verschlossen, so daß der Hochdruckpumpe 18 kein Kraftstoff mehr zufließt.In the connection between the feed pump 10 and the high-pressure pump 18, a fuel metering device 60 is arranged, through which a flow area of the connection to the high pressure pump 18 is adjusted. The fuel metering device 60 is actuated by the control device 46. The fuel metering device 60 has a flow control valve 62 and an actuator 64, which is controlled by the control device 46. By means of the flow control valve 62, the flow area of the connection to the high pressure pump 18 can be adjusted continuously between zero and a maximum flow area. As actuator 64, an electromagnet or a piezoelectric actuator can be used, which is supplied in each case by the control device 46 with a defined electrical voltage and thereby brings the flow control valve 62 in a defined position in which this releases a defined flow area. Under certain operating conditions of the internal combustion engine, in particular in overrun operation, no fuel may be conveyed into the accumulator 32 by the high-pressure pump 18. For this purpose, the flow cross section of the feed pump 10 to the high-pressure pump 18 is completely closed by the fuel metering device 60, so that the high-pressure pump 18 no more fuel flows.

Abhängig von Betriebsparametern der Brennkraftmaschine, wie beispielsweise Drehzahl, Last und anderen, wird durch die Steuereinrichtung 46 ein Solldruck im Speicher 32 vorgegeben. Durch den Drucksensor 52 erhält die Steuereinrichtung 46 ein Signal für den Istdruck im Speicher 32. Der Druck im Speicher 32 ist abhängig von der durch die Hochdruckpumpe 18 in den Speicher 32 geförderten Kraftstoffmenge. Die durch die Hochdruckpumpe 18 geförderte Kraftstoffmenge kann dadurch verändert werden, daß mittels der Kraftstoffzumeßeinrichtung 60 der Durchflußquerschnitt der Verbindung zur Förderpumpe 10 verändert wird. Die Kraftstoffzumeßeinrichtung 60 wird durch die Steuereinrichtung 46 derart angesteuert, daß diese in der Verbindung zur Förderpumpe 10 einen Durchflußquerschnitt einstellt, der so groß ist, daß die der Hochdruckpumpe 18 zufließende Kraftstoffmenge so groß ist, daß die durch die Hochdruckpumpe 18 in den Speicher 32 geförderte Kraftstoffmenge zur Aufrechterhaltung des vorgegebenen Solldrucks im Speicher 32 ausreicht. Wenn der Istdruck im Speicher 32 geringer ist als der Solldruck, so wird durch die Hochdruckpumpe 18 eine zu geringe Kraftstoffmenge gefördert und durch die Steuereinrichtung wird die Kraftstoffzumeßeinrichtung 60 derart angesteuert, daß diese einen größeren Durchflußquerschnitt in der Verbindung zur Förderpumpe 10 freigibt und somit die durch die Hochdruckpumpe 18 geförderte Kraftstoffmenge erhöht wird. Wenn der Istdruck im Speicher 32 höher ist als der Solldruck, so wird durch die Hochdruckpumpe 18 eine zu große Kraftstoffmenge gefördert und durch die Steuereinrichtung 46 wird die Kraftstoffzumeßeinrichtung 60 derart angesteuert, daß diese einen kleineren Durchflußquerschnitt in der Verbindung zur Förderpumpe 10 freigibt und somit die durch die Hochdruckpumpe 18 geförderte Kraftstoffmenge verringert wird.Depending on operating parameters of the internal combustion engine, such as, for example, rotational speed, load and others, the controller 46 sets a desired pressure in the memory 32 specified. By the pressure sensor 52, the control device 46 receives a signal for the actual pressure in the memory 32. The pressure in the memory 32 is dependent on the amount of fuel delivered by the high-pressure pump 18 into the accumulator 32. The amount of fuel delivered by the high-pressure pump 18 can be changed by changing the flow area of the connection to the feed pump 10 by means of the fuel metering device 60. The fuel metering device 60 is controlled by the control device 46 such that it sets in the connection to the feed pump 10, a flow area which is so large that the high-pressure pump 18 inflowing amount of fuel is so large that funded by the high-pressure pump 18 into the memory 32 Amount of fuel to maintain the predetermined target pressure in the memory 32 is sufficient. If the actual pressure in the accumulator 32 is less than the target pressure, then a too small amount of fuel is conveyed by the high-pressure pump 18 and the fuel metering device 60 is controlled by the control device so that it releases a larger flow area in the connection to the feed pump 10 and thus by the high pressure pump 18 delivered amount of fuel is increased. If the actual pressure in the accumulator 32 is higher than the setpoint pressure, then an excessively high fuel quantity is delivered by the high-pressure pump 18 and the fuel metering device 60 is activated by the control device 46 in such a way that it releases a smaller flow cross-section in the connection to the feed pump 10 and thus the is reduced by the high pressure pump 18 funded amount of fuel.

Anhand der Figuren 2 und 3 wird nachfolgend das Saugventil 36 eines Pumpenelements 22 näher erläutert, wobei sämtliche Pumpenelemente 22 gleich ausgebildet sind. In einem Gehäuseteil 70 der Hochdruckpumpe 18 ist ein Zulaufkanal 72 für den von der Förderpumpe 10 geförderten Kraftstoff in den Arbeitsraum 34 ausgebildet. An der Mündung des Zulaufkanals 72 in den Arbeitsraum 34 ist dem Arbeitsraum 34 zugewandt ein Ventilsitz 74 ausgebildet, der beispielsweise zumindest annähernd konisch ausgebildet ist. Das Saugventil 36 weist ein Ventilglied 76 auf, das beispielsweise in Form einer Kugel ausgebildet ist und das mit dem Ventilsitz 74 zur Steuerung der Verbindung des Zulaufkanals 72 mit dem Arbeitsraum 34 zusammenwirkt. Das Ventilglied 76 ist beispielsweise in einem zum Pumpenkolben 26 hin angeordneten Trägerteil 78 aufgenommen. Das Saugventil 36 weist außerdem eine Schließfeder 80 auf, die beispielsweise als Schraubendruckfeder ausgebildet ist und die zwischen dem Pumpenkolben 26 und dem Trägerteil 78 eingespannt ist. Durch die Schließfeder 80 wird das Ventilglied 76 in Schließrichtung zum Ventilsitz 74 hin gedrückt. Das Ventilglied 76 wird außerdem durch den im Arbeitsraum 34 herrschenden Druck in Schließrichtung beaufschlagt.Based on Figures 2 and 3 Below, the suction valve 36 of a pump element 22 is explained in more detail, wherein all pump elements 22 are identical. In one Housing part 70 of the high-pressure pump 18 is an inlet channel 72 for the funded by the pump 10 fuel into the working space 34 is formed. At the mouth of the inlet channel 72 in the working space 34, the working space 34 facing a valve seat 74 is formed, which is for example at least approximately conical. The suction valve 36 has a valve member 76, which is formed for example in the form of a ball and which cooperates with the valve seat 74 for controlling the connection of the inlet channel 72 with the working space 34. The valve member 76 is received, for example, in a pump member 26 towards the arranged support member 78. The suction valve 36 also has a closing spring 80, which is formed for example as a helical compression spring and which is clamped between the pump piston 26 and the support member 78. By the closing spring 80, the valve member 76 is pressed in the closing direction to the valve seat 74. The valve member 76 is also acted upon by the pressure prevailing in the working space 34 in the closing direction.

Der Pumpenkolben 26 weist an seinem dem Ventilglied 76 zugewandten Ende einen im Durchmesser verkleinerten Fortsatz 82 auf, wobei am Übergang vom vollen Durchmesser des Pumpenkolbens 26, an dem dieser in der Zylinderbohrung 24 dicht geführt ist, zum Fortsatz 82 eine Ringschulter 84 gebildet ist, an der sich die Schließfeder 80 abstützt. Die Schließfeder 80 umgibt den Fortsatz 82 und das Trägerteil 78 ist an den Fortsatz 82 anschließend angeordnet. Wenn sich der Pumpenkolben 26 in seinem oberen Totpunkt befindet, das ist die Hubstellung, in der der Pumpenkolben 26 am nächsten zum Gehäuseteil 70 hin angeordnet ist, so ist zwischen dem Fortsatz 82 des Pumpenkolbens 26 und dem Trägerteil 78 ein Abstand in Richtung der Längsachse 27 des Pumpenkolbens 26 vorhanden, wenn sich das Ventilglied 76 in seiner Schließstellung befindet, in der es am Ventilsitz 74 anliegt. Es kann vorgesehen sein, daß das Stirnende des Fortsatzes 82 des Pumpenkolbens 26 einen Anschlag zur Begrenzung der Öffnungsbewegung des Ventilglieds 76 bildet, indem das Trägerteil 78 am Fortsatz 82 zur Anlage kommt. Wenn sich der Pumpenkolben 26 wie in Figur 2 dargestellt in seinem oberen Totpunkt befindet, so ist die Schließfeder 80 des Saugventils 36 stark komprimiert und übt entsprechend eine hohe Kraft auf das Ventilglied 76 aus, mit der dieses gegen den Ventilsitz 74 gedrückt wird. Der durch die Schließfeder 80 und der durch den im Arbeitsraum 34 herrschenden Druck erzeugten Kraft auf das Ventilglied 76 wirkt die durch den im Zulaufkanal 72 herrschenden Druck auf das Ventilglied 76 erzeugte Kraft in Öffnungsrichtung entgegen. Wenn die durch den im Zulaufkanal 72 herrschenden Druck auf das Ventilglied 76 erzeugte Kraft größer ist als die durch die Schließfeder 80 und den im Arbeitsraum 34 herrschenden Druck auf das Ventilglied 76 bewirkte Kraft, so bewegt sich das Ventilglied 76 gegen die Kraft der Schließfeder 80 in Öffnungsrichtung und gibt die Mündung des Zulaufkanals 72 in den Arbeitsraum 34 frei. Der Druck, bei dem das Ventilglied 76 sich in Öffnungsrichtung bewegt, wird als Öffnungsdifferenzdruck des Saugventils 36 bezeichnet.The pump piston 26 has at its end facing the valve member 76 a reduced in diameter extension 82, wherein at the transition from the full diameter of the pump piston 26, where this is tightly guided in the cylinder bore 24 to the extension 82, an annular shoulder 84 is formed on the closing spring 80 is supported. The closing spring 80 surrounds the extension 82 and the carrier part 78 is subsequently arranged on the extension 82. When the pump piston 26 is in its top dead center, which is the stroke position in which the pump piston 26 is arranged closest to the housing part 70, so is a distance in the direction of the longitudinal axis 27 between the extension 82 of the pump piston 26 and the support member 78 the pump piston 26 is present when the valve member 76 is in its closed position in which it is on the valve seat 74th is applied. It can be provided that the front end of the extension 82 of the pump piston 26 forms a stop for limiting the opening movement of the valve member 76 by the support member 78 comes to the extension 82 to the plant. When the pump piston 26 as in FIG. 2 is shown in its top dead center, the closing spring 80 of the suction valve 36 is highly compressed and accordingly exerts a high force on the valve member 76, with which this is pressed against the valve seat 74. The force generated by the closing spring 80 and by the pressure prevailing in the working space 34 on the valve member 76 counteracts the force generated in the inlet channel 72 pressure on the valve member 76 in the opening direction. If the force generated by the pressure prevailing in the inlet channel 72 on the valve member 76 is greater than the force caused by the closing spring 80 and the pressure prevailing in the working space 34 on the valve member 76, the valve member 76 moves against the force of the closing spring 80 in Opening direction and releases the mouth of the inlet channel 72 into the working space 34. The pressure at which the valve member 76 moves in the opening direction is referred to as the opening differential pressure of the suction valve 36.

Beim Saughub bewegt sich der Pumpenkolben 26 von seinem oberen Totpunkt gemäß Figur 2 zu seinem unteren Totpunkt gemäß Figur 3. Beim Saughub des Pumpenkolbens 26 wird die Schließfeder 80 zunehmend entspannt, so daß diese eine geringere Kraft in Schließrichtung auf das Ventilglied 76 bewirkt und entsprechend der Öffnungsdifferenzdruck des Saugventils 36 geringer wird. Wenn sich der Pumpenkolben 26 zu Beginn des Saughubs in seinem oberen Totpunkt befindet, so ist der Öffnungsdifferenzdruck des Saugventils 36 am höchsten und wird nachfolgend als maximaler Öffnungsdifferenzdruck bezeichnet. Mit zunehmendem Saughub des Pumpenkolbens 26 nimmt der Öffnungsdifferenzdruck ab, wobei sich in einem Bereich des mittleren Saughubs, das ist eine mittlere Hubstellung des Pumpenkolbens 26 zwischen dessen oberem Totpunkt und dessen unterem Totpunkt, ein mittlerer Öffnungsdifferenzdruck des Saugventils 36 ergibt. Wenn sich der Pumpenkolben 26 in seinem unteren Totpunkt befindet, so ist der Öffnungsdifferenzdruck des Saugventils 36 am geringsten und wird nachfolgend als minimaler Öffnungsdifferenzdruck bezeichnet. Es ist vorgesehen, daß der minimale Öffnungsdifferenzdruck des Saugventils 36 weniger als 0,9 bar, vorzugsweise höchstens 0,8 bar beträgt. Der mittlere Öffnungsdifferenzdruck und der maximale Öffnungsdifferenzdruck des Saugventils 36 sind dann abhängig von der Federrate c der Schließfeder 80, das ist die Änderung der durch diese erzeugten Kraft bezogen auf den Federweg, und vom Hub des Pumpenkolbens 26 zwischen dessen oberem und unterem Totpunkt. Die Federrate c der Schließfeder 80 kann einen kleinen Wert aufweisen, wobei sich die durch die Schließfeder 80 ausgeübte Kraft auf das Ventilglied 76 jedoch über den relativ großen Saughub des Pumpenkolbens 26 wesentlich ändert. Der mittlere Öffnungsdifferenzdruck des Saugventils 36 ist größer als 0,9 bar. Das Verhältnis zwischen dem mittleren Öffnungsdifferenzdruck und dem minimalen Öffnungsdifferenzdruck des Saugventils 36 ist größer als 1 und beträgt höchstens etwa 10.During the suction stroke, the pump piston 26 moves according to its top dead center FIG. 2 according to its bottom dead center according to FIG. 3 , During the suction stroke of the pump piston 26, the closing spring 80 is increasingly relaxed, so that this causes a smaller force in the closing direction on the valve member 76 and corresponding to the opening differential pressure of the suction valve 36 is lower. When the pump piston 26 is at its top dead center at the beginning of the suction stroke, the opening differential pressure of the suction valve 36 is highest and will be referred to as maximum opening differential pressure hereinafter. As the suction stroke of the pump piston 26 increases, the opening differential pressure decreases. wherein in a region of the middle suction stroke, that is, an average stroke position of the pump piston 26 between the top dead center and the bottom dead center, a mean opening differential pressure of the suction valve 36 results. When the pump piston 26 is at its bottom dead center, the opening differential pressure of the suction valve 36 is the lowest, and is hereinafter referred to as the minimum opening differential pressure. It is envisaged that the minimum opening differential pressure of the suction valve 36 is less than 0.9 bar, preferably at most 0.8 bar. The mean opening differential pressure and the maximum opening differential pressure of the suction valve 36 are then dependent on the spring rate c of the closing spring 80, that is, the change in the force generated by this force relative to the spring travel, and the stroke of the pump piston 26 between the top and bottom dead center. The spring rate c of the closing spring 80 may have a small value, but the force exerted by the closing spring 80 on the valve member 76 substantially changes over the relatively large suction stroke of the pump piston 26. The mean opening differential pressure of the suction valve 36 is greater than 0.9 bar. The ratio between the average opening differential pressure and the minimum opening differential pressure of the suction valve 36 is greater than 1 and is at most about 10.

Dadurch, daß sich der Öffnungsdifferenzdruck des Saugventils 36 während des Saughubs des Pumpenkolbens 26 verringert, wird ein sicheres Öffnen des Saugventils 36 auch bei geringem Druck im Kraftstoffzulaufkanal 72 infolge eines durch die Kraftstoffzumeßeinrichtung 60 eingestellten kleinen Druchflußquerschnitts von der Förderpumpe 10 her erreicht. Es wird hierbei auch sichergestellt, daß die Saugventile 36 sämtlicher Pumpenelemente 22 der Hochdruckpumpe 18 gleichmäßig öffnen und somit eine gleichmäßige Befüllung der Arbeitsräume 34 sämtlicher Pumpenelemente 22 und somit eine gleichförmige Kraftstofförderung durch die Hochdruckpumpe 18 erreicht. Durch Verwendung einer Schließfeder 80 mit geringer Federrate c kann der Einfluß von Toleranzen der Bauteile der Hochdruckpumpe 18 auf den Öffnungsdruck verringert werden und dadurch ebenfalls eine Verbesserung der gleichmäßigen Kraftstofförderung durch sämtliche Pumpenelemente 22 erreicht werden. Außerdem kann durch einen geringen mittleren und minimalen Öffnungsdifferenzdruck des Saugventils 36 die Befüllung des Arbeitsraums 34 verbessert werden, da die beiden füllungsentscheidenden Parameter, nämlich die füllungswirksame Druckdifferenz vor und nach dem Saugventil 36 und die Öffnungsdauer des Saugventils 36, bei geringem Öffnungsdifferenzdruck des Saugventils 36 groß sind. Andererseits kann bei vorgegebener Füllung des Arbeitsraums 34 der Pumpenelemente 22 eine Förderpumpe 10 mit geringerer Förderleistung und entsprechend schwächer dimensioniertem Antrieb verwendet werden, die dadurch kostengünstiger ist. Dadurch, daß mittels der Kraftstoffzumeßeinrichtung 60 der Druchflußquerschnitt von der Förderpumpe 10 her vollständig verschließbar ist, ist auch bei geringem Öffnungsdifferenzdruck des Saugventils 36 eine Nullförderung der Hochdruckpumpe 18 sichergestellt.Characterized in that the opening differential pressure of the suction valve 36 is reduced during the intake stroke of the pump piston 26, a safe opening of the suction valve 36 is achieved even at low pressure in the fuel supply passage 72 due to a set by the fuel metering 60 small Druchflußquerschnitts from the feed pump 10 ago. It is also ensured that the suction valves 36 of all pump elements 22 of the high-pressure pump 18 open uniformly and thus a uniform filling of the working spaces 34 of all pump elements 22 and thus a uniform delivery of fuel through the high-pressure pump 18 is achieved. By using a closing spring 80 with a low spring rate c, the influence of tolerances of the components of the high-pressure pump 18 can be reduced to the opening pressure and thus also an improvement of the uniform fuel delivery can be achieved by all pump elements 22. In addition, by a small mean and minimum opening differential pressure of the suction valve 36, the filling of the working space 34 can be improved, since the two filling decisive parameters, namely the filling effective pressure difference before and after the suction valve 36 and the opening duration of the suction valve 36, at low opening differential pressure of the suction valve 36 large are. On the other hand, for a given filling of the working space 34 of the pump elements 22, a delivery pump 10 with a lower delivery rate and a correspondingly smaller dimensioned drive can be used, which is less expensive. Characterized in that by means of the fuel metering device 60 of the Druchflußquerschnitt from the feed pump 10 forth is completely closed, a zero promotion of the high-pressure pump 18 is ensured even at low opening differential pressure of the suction valve 36.

Claims (4)

  1. Fuel injection device for an internal combustion engine, having a high-pressure pump (18) by means of which fuel is delivered at high pressure into an accumulator (32) to which injectors (40) arranged at the cylinders of the internal combustion engine are connected, having a delivery pump (10) by means of which fuel is delivered from a storage tank (12) to the high-pressure pump (18), wherein the high-pressure pump (18) has at least one pump element (22) with a pump piston (26) which delimits a working chamber (34) and which is driven in a reciprocating movement, and wherein the working chamber (34) has a connection to the pressure side of the delivery pump (10), in which connection there is arranged a suction valve (36) which opens in the direction of the working chamber (34), through which suction valve fuel flows into the working chamber (34) during the suction stroke of the pump piston (26), wherein the suction valve (36) has a valve element (76) which is loaded in a closing direction by a closing spring (80), wherein the closing spring (80) is at least indirectly supported on the pump piston (26), and wherein, with progressive suction stroke of the pump piston (26), the closing force exerted on the valve element (76) by the closing spring (80) decreases, characterized in that a minimum opening differential pressure of the suction valve (36) is less than 0.9 bar, in that a mean opening differential pressure of the suction valve (36) in an intermediate position of the pump piston (26) in the region of the midway point of the suction stroke of the pump piston (26) is at least 0.9 bar, and in that the ratio of mean opening differential pressure to minimum opening differential pressure of the suction valve (36) is greater than 1, and is at most 10.
  2. Fuel injection device according to Claim 1, characterized in that the minimum opening differential pressure of the suction valve (36) is at most 0.8 bar.
  3. Fuel injection device according to either of Claims 1 and 2, characterized in that a fuel metering device (60) is arranged between the delivery pump (10) and the suction valve (36), by means of which fuel metering device a throughflow cross section for the fuel flowing to the suction valve (36) is adjusted, and by means of which fuel metering device the throughflow cross section can be completely closed.
  4. Fuel injection device according to Claim 3, characterized in that, by means of the fuel metering device (60), the throughflow cross section is adjusted such that the high-pressure pump (18) delivers into the accumulator (32) a fuel flow rate required for maintaining a predefined pressure in the accumulator (32).
EP03004643.7A 2002-04-23 2003-03-03 Fuel injection system for internal combustion engine Expired - Lifetime EP1357283B1 (en)

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EP1357283A2 (en) 2003-10-29
JP4395319B2 (en) 2010-01-06
US20030213471A1 (en) 2003-11-20
DE10218022A1 (en) 2003-11-06
JP2003314409A (en) 2003-11-06
US6959694B2 (en) 2005-11-01
EP1357283A3 (en) 2004-09-22

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