EP0408915B1 - Fuel injection pump for internal combustion engines - Google Patents

Fuel injection pump for internal combustion engines Download PDF

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Publication number
EP0408915B1
EP0408915B1 EP90111723A EP90111723A EP0408915B1 EP 0408915 B1 EP0408915 B1 EP 0408915B1 EP 90111723 A EP90111723 A EP 90111723A EP 90111723 A EP90111723 A EP 90111723A EP 0408915 B1 EP0408915 B1 EP 0408915B1
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EP
European Patent Office
Prior art keywords
pump
flow
throttle
section
passage
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP90111723A
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German (de)
French (fr)
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EP0408915A1 (en
Inventor
Dominique Buisson
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Robert Bosch GmbH
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Robert Bosch GmbH
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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
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/20—Varying fuel delivery in quantity or timing
    • F02M59/36—Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
    • F02M59/366—Valves being actuated electrically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B3/00—Engines characterised by air compression and subsequent fuel addition
    • F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
    • 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
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/007—Venting means

Definitions

  • the invention relates to an electrically controlled pump nozzle according to the preamble of claim 1.
  • control valve may become blocked, i.e. that it gets stuck in this switch position. Then there is the possibility that fuel is still led into the pump work space by sucking back fuel by means of the pump piston. This can be done, for example, via a check valve that is no longer fully closed, which is intended to decouple the pump work space from the tank, or via a continuously open throttle in the return line. If the injection process continues unintentionally, there is a risk that the motor vehicle operated by the internal combustion engine will get out of control. This must be prevented.
  • the pump nozzle according to the invention with the characterizing features of claim 1 has the advantage that the problem occurring in the prior art is solved in a safe manner.
  • the venturi pump which works as a jet pump, puts the pump work space under negative pressure, as a result of which fuel is withdrawn from the pump work space and thus an unwanted injection is reliably prevented.
  • the features of claim 3 additionally ensure cooling of the control valve without interfering with the mode of operation of the venturi pump, with simultaneous decoupling of the control surges from the control valve.
  • damping of the actuator movement of the control valve is achieved.
  • the embodiment of the electrically controlled pump nozzle according to the invention shown in the drawing consists of a piston injection pump 10, which is mechanically driven in a manner not shown but is known to be driven by a camshaft, the pump housing of which is driven by a constant stroke and in a Cylinder bore 11 receives pump piston 12 and on the end carries an injection nozzle 14 of a known type, which is therefore not shown in more detail, which is fastened by means of a dashed-dot screw sleeve 19 with the interposition of a pressure valve 13.
  • the pump piston 12 is driven by known drive means, which are therefore only indicated by an arrow 15, via a pump tappet against the restoring force of a tappet spring.
  • the pump piston 12 delimits, with its end face 16, a pump working chamber 17 located in the cylinder bore 11, which is closed by the pressure valve 13 on the injection nozzle side and can be connected to the injection nozzle 14 via a pressure channel 18.
  • This pressure valve 13 can also be omitted because of the short length of the pressure channel 18 between the pump work chamber 17 and the injector 14.
  • the pump work chamber 17 is in the designated bottom dead center position UT of the pump piston 12 by a feed pump 20 with a low inlet pressure of z. B. 4 bar of fuel supplied.
  • the fuel reaches a control valve 24 via a throughflow section 22 formed as part of a throughflow line 21 with a low pressure chamber 23 therein, which in the open position shown shows the fuel via a further part of the throughflow line 21, a throughflow channel 25 , passes to the pump work space 17.
  • a partial flow of the fuel delivered by the feed pump 20 passes via a connecting section 26 branching off from the throughflow section 22 to a venturi pump 28 with a throughflow throttle 29 located in the flow direction, which opens on the outflow side into a return line 31 leading to a tank 30.
  • the actuator 35 is surrounded by a rinsing chamber 36 which is connected on the one hand to the flow section 22 via a rinsing line 37 and on the other hand to the return line 31 via an outlet channel 38.
  • the flushing volume flowing through the flushing chamber 36 is limited by a metering throttle 39 inserted into the flushing line 37 and can be additionally influenced via a dashed orifice 40 located in the outlet channel 38, the flow cross-section of which is equal to or smaller than that of the metering restrictor 39.
  • the metering throttle 39 and the outlet throttle 40 can also be replaced by a corresponding choice of the flow cross section of the lines receiving them.
  • the lost heat of the actuator 35 is dissipated via the permanent flushing of the flushing chamber 36 and, via the dimensioning of the flow cross sections of the metering throttle 39 on the one hand and the outlet throttle 40 on the other hand, a small back pressure is generated in the flushing chamber 36, which leads to a damped switching behavior of the control valve. Furthermore, the metering throttle 39 weakens the control pressure surges which occur when the control valve 24 is reversed due to the relief of the pump work space 17, as a result of which the operational reliability of the control valve 24 is increased.
  • the power supply to the actuator 35 of the control valve 24 is switched off in accordance with the operating data determined in an electronic control device.
  • the control valve 24 is switched over to its drawn open position.
  • the pump work space 17 is relieved of pressure in the low pressure space 23 and the pressure in the pump work space 17 drops suddenly.
  • the pressure valve 13 and the injector 14 close, so that the injection is finished.
  • the flow cross sections of the flow restrictor 29 and the suction restrictor 32 are coordinated so that with a receding pump piston 12 towards the bottom dead center position UT even with open ner annular groove 34, a rapid fuel filling of the pump work space 17 and then a flushing of the pump work space 17 to cool it and to remove air and steam bubbles.
  • the pump piston 12 would be able, if the venturi nozzle 28 was not present, to use the fuel which it received, for example, via leakage currents as a result of part tolerances, defective components or the volume of lines or filters, so it is also available via the return line 31 and the connecting channel 33 to undesirably continue the injection.
  • the open-controlled Annular groove 34 withdraws fuel from the pump work chamber 17 via the suction effect of the venturi pump 28 and generates a negative pressure, by means of which an uncontrolled injection is prevented.

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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

Stand der TechnikState of the art

Die Erfindung betrifft eine elektrisch gesteuerte Pumpedüse gemäß Oberbegriff des Anspruchs 1.The invention relates to an electrically controlled pump nozzle according to the preamble of claim 1.

Bei einer solchen, aus der US-PS 4 669 659 bekannten Pumpedüse für Dieselmotoren, die direkt in den Zylinderkopf der zugehörigen Brennkraftmaschine eingebaut wird und in einem gemeinsamen Gehäuse sowohl die mechanisch angetriebene Kolbeneinspritzpumpe als auch die zugehörige Einspritzdüse umfaßt, wird die beim Förderdruck des Pumpenkolbens aus dem Pumpenarbeitsraum zur Einspritzdüse verdrängte Kraftstoffeinspritzmenge durch die Einschaltdauer eines stromlos offenen, elektromagnetisch betätigten Steuerventils bestimmt, das in einen den Pumpenarbeitsraum mit einem Niederdruckraum verbindenden Überströmkanal eingesetzt ist. Dabei steht dann der erste, dauernd mit dem Pumpenarbeitsraum verbundene Abschnitt des Überströmkanals unter dem vollem Einspritzdruck, wenn das Steuerventil zur Steuerung der Kraftstoffeinspritzung die Verbindung zwischen den beiden Abschnitten des Überströmkanals und damit den Abschluß des Kraftstoffes zum Niederdruckraum sperrt.In such a pump nozzle for diesel engines, known from US Pat. No. 4,669,659, which is installed directly in the cylinder head of the associated internal combustion engine and includes both the mechanically driven piston injection pump and the associated injection nozzle in a common housing, the pump pressure is at the delivery pressure of the pump piston Fuel injection quantity displaced from the pump work chamber to the injection nozzle is determined by the duty cycle of a normally open, electromagnetically operated control valve which is inserted into an overflow channel connecting the pump work chamber with a low pressure chamber. The first section of the overflow channel, which is permanently connected to the pump work chamber, is then under full injection pressure when the control valve for controlling the fuel injection blocks the connection between the two sections of the overflow channel and thus the fuel from the low pressure chamber.

In seltenen Fällen kann es vorkommen, daß das Steuerventil blokkiert, d.h. daß es in dieser Schaltstellung hängenbleibt. Dann besteht die Möglichkeit, daß durch Rücksaugen von Kraftstoff mittels des Pumpenkolbens weiterhin Kraftstoff in den Pumpenarbeitsraum geführt wird. Dies kann beispielsweise über ein nicht mehr völlig schließendes Rückschlagventil erfolgen, das den Pumpenarbeitsraum zum Tank hin entkoppeln soll oder über eine dauernd offene Drossel in der Rücklaufleitung. Wenn sich der Einspritzvorgang so ungewollt fortsetzt, besteht die Gefahr, daß das durch die Brennkraftmaschine betriebene Kraftfahrzeug außer Kontrolle gerät. Dies muß verhindert werden.In rare cases, the control valve may become blocked, i.e. that it gets stuck in this switch position. Then there is the possibility that fuel is still led into the pump work space by sucking back fuel by means of the pump piston. This can be done, for example, via a check valve that is no longer fully closed, which is intended to decouple the pump work space from the tank, or via a continuously open throttle in the return line. If the injection process continues unintentionally, there is a risk that the motor vehicle operated by the internal combustion engine will get out of control. This must be prevented.

Durch die GB-A- 2 134 987 ist es für eine Kraftstoffeinspritzpumpe bekannt, bei einer Funktionsstörung des Steuerventils den Pumpenarbeitsraum mit Hilfe einer Elektropumpe leerzusaugen.From GB-A-2 134 987 it is known for a fuel injection pump to empty the pump work space with the aid of an electric pump in the event of a malfunction of the control valve.

Vorteile der ErfindungAdvantages of the invention

Die erfindungsgemäße Pumpedüse mit den kennzeichnenden Merkmalen des Anspruchs 1 hat demgegenüber den Vorteil, daß das beim Stand der Technik auftretende Problem auf sichere Weise gelöst wird. Gemäß der Erfindung setzt die als Strahlpumpe arbeitende Venturi-Pumpe den Pumpenarbeitsraum unter Unterdruck, wodurch dem Pumpenarbeitsraum Kraftstoff entzogen und damit eine ungewollte Einspritzung sicher unterbunden wird.The pump nozzle according to the invention with the characterizing features of claim 1 has the advantage that the problem occurring in the prior art is solved in a safe manner. According to the invention, the venturi pump, which works as a jet pump, puts the pump work space under negative pressure, as a result of which fuel is withdrawn from the pump work space and thus an unwanted injection is reliably prevented.

Als weitere Vorteile ergeben sich bei geschlossenem Überströmventil eine durch die Saugwirkung der Venturi-Pumpe erzwungene Spülung des Pumpenarbeitsraums, wobei dieser entlüftet und gasblasenfrei gehalten wird. Infolge der raschen Kraftstoffüllung des Pumpenarbeitsraums durch die von der Venturi-Pumpe hervorgerufene Zwangsspülung, ergibt sich, nach einem zuvor entleerten Pumpenarbeitsraum, ein verbessertes Wiederstartverhalten der Brennkraftmaschine. Durch die in den Ansprüchen 2 bis 4 aufgeführten Maßnahmen und Merkmale sind vorteilhafte Ausgestaltungen und Weiterbildungen der im Anspruch 1 angegebenen Pumpedüse möglich. So ergibt sich durch die vorgeschlagenen Verbesserungen gemäß Anspruch 2 eine äußerst einfache und störungsunanfällige Bauweise der Venturi-Pumpe, mittels der die Pumpedüse ohne Funktionsverlust sicher betreibbar ist.As a further advantage, when the overflow valve is closed, the pump work space is forced to be flushed by the suction effect of the venturi pump, the work space being vented and kept free of gas bubbles. As a result of the rapid fuel filling of the pump work space through the forced flushing caused by the Venturi pump, the internal combustion engine has an improved restart behavior after a previously empty pump work space. By the measures and features listed in claims 2 to 4 advantageous refinements and developments of the pump nozzle specified in claim 1 possible. The proposed improvements according to claim 2 result in an extremely simple and failure-prone design of the venturi pump, by means of which the pump nozzle can be operated safely without loss of function.

Durch die Merkmale des Anspruchs 3 wird zusätzlich eine Kühlung des Steuerventils sichergestellt, ohne die Wirkungsweise der Venturi-Pumpe zu stören, und zwar bei gleichzeitiger Abkopplung der Absteuerstöße vom Steuerventil.The features of claim 3 additionally ensure cooling of the control valve without interfering with the mode of operation of the venturi pump, with simultaneous decoupling of the control surges from the control valve.

Gemäß der kennzeichnenden Merkmale des Anspruchs 4 wird eine Dämpfung der Stellgliedbewegung des Steuerventils erreicht.According to the characterizing features of claim 4, damping of the actuator movement of the control valve is achieved.

Zeichnungdrawing

Ein Ausführungsbeispiel der erfindungsgemäß ausgestalteten Pumpedüse ist in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert; dazu zeigt die einzige Figur die wichtigsten Bauteile in einer die Strömungswege hervorhebenden schematisierten Darstellung.An embodiment of the pump nozzle designed according to the invention is shown in the drawing and explained in more detail in the following description; the single figure shows the most important components in a schematic representation emphasizing the flow paths.

Beschreibung der AusführungsbeispieleDescription of the embodiments

Das in der Zeichnung dargestellte Ausführungsbeispiel der erfindungsgemäßen, elektrisch gesteuerten Pumpedüse besteht aus einer, in nicht näher dargestellten, jedoch in bekannter Weise von einer Nockenwelle mechanisch angetriebenen Kolbeneinspritzpumpe 10, deren Pumpengehäuse einer mit konstantem Hub angetriebenen und in einer Zylinderbohrung 11 geführten Pumpenkolben 12 aufnimmt und stirnseitig eine mittels einer strichpunktiert angedeuteten Schraubhülse 19 unter Zwischenschaltung eines Druckventils 13 befestigte Einspritzdüse 14 bekannter und deshalb nicht näher dargestellter Bauart trägt.The embodiment of the electrically controlled pump nozzle according to the invention shown in the drawing consists of a piston injection pump 10, which is mechanically driven in a manner not shown but is known to be driven by a camshaft, the pump housing of which is driven by a constant stroke and in a Cylinder bore 11 receives pump piston 12 and on the end carries an injection nozzle 14 of a known type, which is therefore not shown in more detail, which is fastened by means of a dashed-dot screw sleeve 19 with the interposition of a pressure valve 13.

Der Pumpenkolben 12 wird von bekannten, deshalb nur durch einen Pfeil 15 angedeuteten Antriebsmitteln über einen Pumpenstössel entgegen der Rückstellkraft einer Stösselfeder angetrieben. Der Pumpenkolben 12 begrenzt mit seiner Stirnfläche 16 einen in der Zylinderbohrung 11 befindlichen Pumpenarbeitsraum 17 der einspritzdüsenseitig vom Druckventil 13 abgeschlossen und über einen Druckkanal 18 mit der Einspritzdüse 14 verbindbar ist. Dieses Druckventil 13 kann aber auch wegen der kurzen Länge des Druckkanals 18 zwischen Pumpenarbeitsraum 17 und Einspritzdüse 14 entfallen.The pump piston 12 is driven by known drive means, which are therefore only indicated by an arrow 15, via a pump tappet against the restoring force of a tappet spring. The pump piston 12 delimits, with its end face 16, a pump working chamber 17 located in the cylinder bore 11, which is closed by the pressure valve 13 on the injection nozzle side and can be connected to the injection nozzle 14 via a pressure channel 18. This pressure valve 13 can also be omitted because of the short length of the pressure channel 18 between the pump work chamber 17 and the injector 14.

Dem Pumpenarbeitsraum 17 wird in der bezeichneten unteren Totpunktlage UT des Pumpenkolbens 12 von einer Förderpumpe 20 unter niedrigem Zulaufdruck von z. B. 4 bar stehender Kraftstoff zugeführt. Der Kraftstoff gelangt dabei, von der Förderpumpe 20 ausgehend, über einen als Teil einer Durchströmleitung 21 ausgebildeten Durchströmabschnitt 22 mit einem darin enthaltenden Niederdruckraum 23 zu einem Steuerventil 24, das in der gezeichneten Offenstellung den Kraftstoff über einen weiteren Teil der Durchströmleitung 21, einen Durchströmkanal 25, zum Pumpenarbeitsraum 17 durchläßt. Ein Teilstrom des von der Förderpumpe 20 geförderten Kraftstoffes gelangt über einen von dem Durchströmabschnitt 22 abzweigenden Verbindungsabschnitt 26 zu einer Venturi-Pumpe 28 mit einer in Strömungsrichtung liegenden Durchströmdrossel 29, die abströmseitig in eine zu einem Tank 30 führende Rücklaufleitung 31 mündet. An die Durchströmdrossel 29 ist eine im Querschnitt kleinere Saugdrossel 32, vorzugsweise in rechtwinkliger Stellung, angeschlossen, die über einen Verbindungskanal 33 mit einer in die Wand der Zylinderbohrung 11 eingearbeiteten Ringnut 34 verbunden ist. In der gezeichneten UT-Lage des Pumpenkolbens 12 ist diese soweit zurückgewichen, daß ein Kraftstoffluß aus dem Pumpenarbeitsraum 17 über die Ringnut 34 zum Verbindungskanal 33 erfolgen kann. Das als 2/2-Wegeventil arbeitende Steuerventil 24 ist ein Magnetventil, dessen Stellglied 35 eine Offen- und eine Schließstellung schaltet. Das Stellglied 35 ist von einem Spülraum 36 umgeben, der einerseits über eine Spülleitung 37 mit dem Durchströmabschnitt 22 und andererseits über einen Ablaufkanal 38 mit der Rücklaufleitung 31 verbunden ist. Die durch den Spülraum 36 fließende Spülmenge wird begrenzt durch eine in die Spülleitung 37 eingeführte Dosierdrossel 39 und kann über eine in dem Ablaufkanal 38 befindliche, gestrichelt dargestellte Ablaufdrossel 40, deren Durchströmquerschnitt gleich oder kleiner ist, als jener der Dosierdrossel 39, zusätzlich beeinflußt werden. Die Dosierdrossel 39 und die Ablaufdrossel 40 können auch durch eine entsprechende Wahl des Strömungsquerschnitts der sie aufnehmenden Leitungen ersetzt werden.The pump work chamber 17 is in the designated bottom dead center position UT of the pump piston 12 by a feed pump 20 with a low inlet pressure of z. B. 4 bar of fuel supplied. Starting from the feed pump 20, the fuel reaches a control valve 24 via a throughflow section 22 formed as part of a throughflow line 21 with a low pressure chamber 23 therein, which in the open position shown shows the fuel via a further part of the throughflow line 21, a throughflow channel 25 , passes to the pump work space 17. A partial flow of the fuel delivered by the feed pump 20 passes via a connecting section 26 branching off from the throughflow section 22 to a venturi pump 28 with a throughflow throttle 29 located in the flow direction, which opens on the outflow side into a return line 31 leading to a tank 30. A suction throttle 32 with a smaller cross-section, preferably in a right-angled position, is connected to the flow restrictor 29 and is incorporated in the wall of the cylinder bore 11 via a connecting channel 33 Ring groove 34 is connected. In the drawn UT position of the pump piston 12, this has withdrawn to such an extent that a fuel flow from the pump work space 17 can take place via the annular groove 34 to the connecting channel 33. The control valve 24, which operates as a 2/2-way valve, is a solenoid valve, the actuator 35 of which switches an open and a closed position. The actuator 35 is surrounded by a rinsing chamber 36 which is connected on the one hand to the flow section 22 via a rinsing line 37 and on the other hand to the return line 31 via an outlet channel 38. The flushing volume flowing through the flushing chamber 36 is limited by a metering throttle 39 inserted into the flushing line 37 and can be additionally influenced via a dashed orifice 40 located in the outlet channel 38, the flow cross-section of which is equal to or smaller than that of the metering restrictor 39. The metering throttle 39 and the outlet throttle 40 can also be replaced by a corresponding choice of the flow cross section of the lines receiving them.

Über die permanente Durchspülung des Spülraums 36 wird die Verlustwärme des Stellgliedes 35 abgeführt und über die Dimensionierung der Strömungsquerschnitte der Dosierdrossel 39 einerseits und der Ablaufdrossel 40 andererseits ein geringer Rückstau im Spülraum 36 erzeugt, der zu einem gedämpften Schaltverhalten des Steuerventils führt. Desweiteren bewirkt die Dosierdrossel 39 eine Abschwächung der Absteuerdruckstöße, die beim Umsteuern des Steuerventils 24 durch die Entlastung des Pumpenarbeitsraums 17 auftreten, wodurch die Betriebssicherheit des Steuerventils 24 erhöht wird.The lost heat of the actuator 35 is dissipated via the permanent flushing of the flushing chamber 36 and, via the dimensioning of the flow cross sections of the metering throttle 39 on the one hand and the outlet throttle 40 on the other hand, a small back pressure is generated in the flushing chamber 36, which leads to a damped switching behavior of the control valve. Furthermore, the metering throttle 39 weakens the control pressure surges which occur when the control valve 24 is reversed due to the relief of the pump work space 17, as a result of which the operational reliability of the control valve 24 is increased.

Die beschriebene Anordnung ergibt nun folgenden Funktions- und Wirkungsablauf: Beginnt der Pumpenkolben 12, ausgehend von seiner dargestellten unteren Totpunktlage UT seinen Druckhub, dann wird der von der Förderpumpe 20 im Pumpenarbeitsraum 17 zugeführte Kraftstoff beim ersten Hubteil sowohl über die noch offenliegende Ringnut 34 in den Verbindungskanal 33 und weiter über die Saugdrossel 32, die Durchströmdrossel 29, die Durchlaufleitung 31 und letztlich zum Tank 30 als auch über den Durchströmkanal 25 und das offene Steuerventil 24 zum Niederdruckraum 23, der als Speicher wirkt, zurückgedrückt.The arrangement described now results in the following sequence of functions and effects: If the pump piston 12 starts its pressure stroke starting from its illustrated bottom dead center position UT, then the fuel supplied by the feed pump 20 in the pump working space 17 becomes both in the first stroke part via the still open annular groove 34 in the connection channel 33 and further via the suction throttle 32, the flow restrictor 29, the flow line 31 and ultimately to the tank 30 as well as via the flow channel 25 and the open control valve 24 to the low-pressure chamber 23, which acts as a memory.

Nach Verschließen der Ringnut 34 durch den sich weiter aus der UT-Lage entfernenden Pumpenkolben 12 wird noch so lange Kraftstoff über den Durchströmkanal 25 verdrängt, bis zur Einleitung des wirksamen Förderbeginns das Steuerventil in seine Schließstellung umschaltet. Der jetzt schlagartig sich im Pumpenarbeitsraum 17 aufbauende Kraftstoffdruck öffnet das Druckventil 13 und der Kraftstoff wird über den Druckkanal 18 zur Einspritzdüse 14 gefördert. Von dort gelangt er in bekannter Weise in den Brennraum der Brennkraftmaschine.After the annular groove 34 has been closed by the pump piston 12, which moves further away from the UT position, fuel is displaced via the flow-through channel 25 until the control valve switches to its closed position until the effective start of delivery. The fuel pressure which suddenly builds up in the pump work chamber 17 opens the pressure valve 13 and the fuel is conveyed via the pressure channel 18 to the injection nozzle 14. From there it reaches the combustion chamber of the internal combustion engine in a known manner.

Zur Beendigung der Kraftstoffförderung zum Brennraum der Brennkraftmaschine wird die Stromzufuhr zum Stellglied 35 des Steuerventils 24 entsprechend den in einem elektronischen Regelgerät ermittelten Betriebsdaten abgeschaltet. Das Steuerventil 24 wird dabei in seine gezeichnete Offenstellung umgeschaltet. Dadurch entlastet sich der Pumpenarbeitsraum 17 in den Niederdruckraum 23 und der Druck im Pumpenarbeitsraum 17 fällt schlagartig ab. Somit schließt das Druckventil 13 und die Einspritzdüse 14, so daß die Einspritzung beendet ist.To end the fuel delivery to the combustion chamber of the internal combustion engine, the power supply to the actuator 35 of the control valve 24 is switched off in accordance with the operating data determined in an electronic control device. The control valve 24 is switched over to its drawn open position. As a result, the pump work space 17 is relieved of pressure in the low pressure space 23 and the pressure in the pump work space 17 drops suddenly. Thus, the pressure valve 13 and the injector 14 close, so that the injection is finished.

Unabhängig von der Schaltstellung des Steuerventils 24 fließt bei angetriebener Förderpumpe 20 über den Durchströmabschnitt 22 und den Verbindungsabschnitt 26 dauernd Kraftstoff von der Förderpumpe 20 über die Venturi-Pumpe 28 und die Rücklaufleitung 31 zum Tank 30. Durch die partielle Geschwindigkeitsanhebung über die Querschnittseinengung in der Durchströmdrossel 29 sinkt hier der statische Druck, wodurch im Verbindungskanal 33 eine Saugwirkung erzeugt wird. Diese führt, wenn der Pumpkolben 12 sich im Bereich seines unteren Totpunktes UT befindet und die Ringnut 34 hinsichtlich ihrer Verbindung zum Pumpenarbeitsraum 17 aufgesteuert ist, zu einem Kraftstofffluß von der Förderpumpe 20 entsprechend den nebengesetzten Pfeilen über den Durchströmabschnitt 22 mit dem Niederdruckraum 23, das sich in Offenstellung befindliche Steuerventil 24, den Durchströmkanal 25 zum Pumpenarbeitsraum 17 und über die Ringnut 34, den Verbindungskanal 33 zur Venturi-Pumpe 28 und von hier über die Rücklaufleitung 31 zum Tank 30. Die Menge dieses Kraftstoffflusses hängt von der Stärke der über den Treibstrom durch die Durchströmdrossel 29 hervorgerufene Sogwirkung ab und wird zudem mitbeeinflußt von dem Strömungsquerschnitt der Saugdrossel 32. Die Strömungsguerschnitte der Durchströmdrossel 29 und der Saugdrossel 32 sind so abgestimmt, daß bei einem zurückweichenden Pumpenkolben 12 in Richtung zur unteren Totpunktlage UT auch bei gleichzeitig offener Ringnut 34 eine rasche Kraftstoffüllung des Pumpenarbeitsraums 17 und danach eine Spülung des Pumpenarbeitsraums 17 zu dessen Kühlung und zur Abfuhr von Luft- und Dampfblasen erfolgt.Regardless of the switching position of the control valve 24, when the feed pump 20 is driven, fuel flows continuously from the feed pump 20 via the venturi pump 28 and the return line 31 to the tank 30 via the flow section 22 and the connecting section 26 29 the static drops here Pressure, whereby a suction effect is generated in the connecting channel 33. This leads, when the pump piston 12 is in the region of its bottom dead center UT and the annular groove 34 is opened with respect to its connection to the pump work chamber 17, to a fuel flow from the feed pump 20 in accordance with the arrows next to it via the flow section 22 with the low pressure chamber 23, which is in the open position control valve 24, the flow channel 25 to the pump work chamber 17 and via the annular groove 34, the connecting channel 33 to the venturi pump 28 and from here via the return line 31 to the tank 30. The amount of this fuel flow depends on the strength of the drive current the flow restrictor 29 causes suction effect and is also influenced by the flow cross section of the suction restrictor 32. The flow cross sections of the flow restrictor 29 and the suction restrictor 32 are coordinated so that with a receding pump piston 12 towards the bottom dead center position UT even with open ner annular groove 34, a rapid fuel filling of the pump work space 17 and then a flushing of the pump work space 17 to cool it and to remove air and steam bubbles.

Dieser Vorgang wird unterbrochen, wenn der Pumpenkolben 12 zu Beginn seines Druckhubes die Ringnut 34 abdeckt, bis die Ringnut 34 durch den Pumpenkolben 12 wieder aufgesteuert wird.This process is interrupted when the pump piston 12 covers the annular groove 34 at the beginning of its pressure stroke until the annular groove 34 is opened again by the pump piston 12.

Geht das Steuerventil 24 in seine Schließstellung und blockiert sein Stellglied 35 in dieser Stellung, so wäre der Pumpenkolben 12 bei nicht vorhandener Venturi-Düse 28 in der Lage, mit dem Kraftstoff, der ihm beispielsweise über Leckströme infolge Teiletoleranzen, fehlerhafter Bauelemente oder über das Volumen von Leitungen oder Filtern, so auch über die Rücklaufleitung 31 und den Verbindungskanal 33 zur Verfügung steht, die Einspritzung unerwünschterweise fortzusetzen. In diesem Störfall wird nun bei offengesteuerter Ringnut 34 über die Saugwirkung der Venturi-Pumpe 28 dem Pumpenarbeitsraum 17 Kraftstoff entzogen und ein Unterdruck erzeugt, durch den eine unkontrollierte Einspritzung unterbunden wird. Daraus ist ersichtlich, daß es vorteilhaft ist, die Ringnut 34 im Bereich des unteren Totpunktes UT zu positionieren, wodurch der Pumpenkolben 12 nahe seiner Bewegungsumkehr kaum mehr Saugwirkung entfalten kann und so keine Dominanz über die Saugwirkung der Venturi-Pumpe 28 erfolgen kann. Auch bei geschlossener Ringnut 34 wird durch den dauernd durch die Durchströmdrossel 29 fließenden Kraftstroffstrom ein so hoher Unterdruck in dem die Saugdrossel 32 enthaltenden Verbindungskanal 32 erzeugt, das bei in der Schließstellung hängengebliebenem Steuerventil 24 der sich im Pumpenarbeitsraum 17 beim Saughub des Pumpenkolbens 12 einstellende Unterdruck immer geringer ist, als derjenige im Verbindungskanal 33. Ein Zurücksaugen von Kraftstoff aus der Rücklaufleitung 31 wird somit sicher verhindert.If the control valve 24 goes into its closed position and blocks its actuator 35 in this position, the pump piston 12 would be able, if the venturi nozzle 28 was not present, to use the fuel which it received, for example, via leakage currents as a result of part tolerances, defective components or the volume of lines or filters, so it is also available via the return line 31 and the connecting channel 33 to undesirably continue the injection. In this malfunction, the open-controlled Annular groove 34 withdraws fuel from the pump work chamber 17 via the suction effect of the venturi pump 28 and generates a negative pressure, by means of which an uncontrolled injection is prevented. From this it can be seen that it is advantageous to position the annular groove 34 in the region of the bottom dead center UT, as a result of which the pump piston 12 can scarcely develop any suction effect near its reversal of movement and thus no dominance can take place over the suction effect of the venturi pump 28. Even when the annular groove 34 is closed, the force flow flowing continuously through the flow restrictor 29 generates such a high negative pressure in the connecting channel 32 containing the suction throttle 32 that, when the control valve 24 is stuck in the closed position, the negative pressure that occurs in the pump working chamber 17 during the suction stroke of the pump piston 12 is less than that in the connecting channel 33. Sucking back fuel from the return line 31 is thus reliably prevented.

Claims (4)

  1. Electrically controlled fuel injection pump (10) for internal combustion engines, in particular unit fuel injector for the fuel injection in diesel internal combustion engines, having at least one pump piston (12) which is driven with constant stroke, bounds a pump working space (17) and, during the delivery stroke, delivers fuel, supplied by a feed pump (20) at supply pressure into this pump working space (17), at injection pressure to an injection nozzle (14), having an electrically actuatable control valve (24) which is placed between a through-flow section (22), which is connected to the feed pump (20) and contains a low pressure space (23), and a through-flow passage (25), permanently connected to the pump working space (17), of a through-flow conduit (21) and by means of which the otherwise open connection, for filling the pump working space (17), between the through-flow section (22) and the through-flow passage (25) can be shut off to control the duration of the fuel injection, having a connecting passage (33), connected to the pump working space (17) and only opened by the pump piston (12) in the bottom dead centre (BDC) position of the latter, between the pump working space (17) and a return conduit (31) returning surplus fuel to the tank (30), characterised in that the connecting passage (33) and the return conduit (31) are connected by means of a venturi pump (28) acting as a jet pump, which is connected at the inflow end by a connecting section (26) to the through-flow section (22) of the through-flow conduit (21), is connected at the drain end to the return conduit (31) and is connected at the suction end to the pump working space (17) via the connecting passage (33).
  2. Fuel injection pump (10) according to Claim 1, characterised in that the venturi pump (28) is formed from a larger cross-section through-flow throttle (29) and a smaller suction throttle (32), preferably opening at right angles into the through-flow throttle (29), the through-flow throttle (29) connecting the connecting section (26) to the return conduit (31) and the suction throttle (32) connecting the pump working space (17) to the through-flow throttle (29).
  3. Fuel injection pump (10) according to Claim 1 or 2, having a scavenging space (36) which surrounds the control valve (24) in the region of its actuator (35) and which is connected via a scavenging conduit (37) to the through-flow section (22) of the through-flow conduit (21), characterised in that a metering throttle (39) limiting the supply to the scavenging space (36) is placed in the scavenging conduit (37), the passage cross-section of this metering throttle (39) being smaller than that of the through-flow throttle (29) of the venturi pump (28) and that the scavenging space (36) is connected via a drain passage (38) to the return conduit (31).
  4. Fuel injection pump (10) according to Claim 3, characterised in that a drain throttle (40) is inserted in the drain passage (38), the passage cross-section of which drain throttle (40) being matched to the passage cross-section of the metering throttle (39) in such a way that a back pressure occurs in the scavenging space (36).
EP90111723A 1989-07-20 1990-06-21 Fuel injection pump for internal combustion engines Expired - Lifetime EP0408915B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3924127A DE3924127A1 (en) 1989-07-20 1989-07-20 FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES
DE3924127 1989-07-20

Publications (2)

Publication Number Publication Date
EP0408915A1 EP0408915A1 (en) 1991-01-23
EP0408915B1 true EP0408915B1 (en) 1992-12-02

Family

ID=6385518

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90111723A Expired - Lifetime EP0408915B1 (en) 1989-07-20 1990-06-21 Fuel injection pump for internal combustion engines

Country Status (4)

Country Link
US (1) US4982713A (en)
EP (1) EP0408915B1 (en)
JP (1) JPH0357874A (en)
DE (2) DE3924127A1 (en)

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DE4211651B4 (en) * 1992-04-07 2004-11-18 Robert Bosch Gmbh Fuel injection device, in particular pump nozzle for internal combustion engines
FR2695169B1 (en) * 1992-08-27 1994-11-04 Melchior Jean Liquid fuel injection device for internal combustion engine and engine equipped with such a device.
JPH0626161U (en) * 1992-09-02 1994-04-08 株式会社寺田電機製作所 Pressure contact type terminal
EP0590362B1 (en) * 1992-09-29 1996-10-23 Steyr Nutzfahrzeuge Ag Cam drive arrangement for driving the pump piston of an injector pump of a four-stroke internal combustion engine
DE4332119B4 (en) * 1993-09-22 2006-04-20 Robert Bosch Gmbh Fuel injection device for internal combustion engines
EP0893598B1 (en) * 1997-07-26 2003-05-28 Delphi Technologies, Inc. Fuel system
SE521406C2 (en) * 1998-10-23 2003-10-28 Scania Cv Ab Combustion engine fuel injection device
GB0119218D0 (en) * 2001-08-07 2001-09-26 Delphi Tech Inc Fuel injector
GB0209146D0 (en) * 2002-04-22 2002-05-29 Delphi Tech Inc Fuel pump
US7690361B2 (en) 2007-09-28 2010-04-06 Cummins Inc. System and method for metering fuel in a high pressure pump system
FI122557B (en) * 2009-04-02 2012-03-30 Waertsilae Finland Oy Fuel injection arrangement for a piston engine

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JPS60204961A (en) * 1984-03-29 1985-10-16 Mazda Motor Corp Fuel injection unit of diesel engine
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JPH01187363A (en) * 1988-01-21 1989-07-26 Toyota Motor Corp Fuel injection valve for internal combustion engine

Also Published As

Publication number Publication date
US4982713A (en) 1991-01-08
EP0408915A1 (en) 1991-01-23
DE59000535D1 (en) 1993-01-14
JPH0357874A (en) 1991-03-13
DE3924127A1 (en) 1991-01-31

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