EP1144851A1 - Fuel injection system - Google Patents

Fuel injection system

Info

Publication number
EP1144851A1
EP1144851A1 EP00988551A EP00988551A EP1144851A1 EP 1144851 A1 EP1144851 A1 EP 1144851A1 EP 00988551 A EP00988551 A EP 00988551A EP 00988551 A EP00988551 A EP 00988551A EP 1144851 A1 EP1144851 A1 EP 1144851A1
Authority
EP
European Patent Office
Prior art keywords
fuel
pressure
low
injection system
fuel injection
Prior art date
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.)
Granted
Application number
EP00988551A
Other languages
German (de)
French (fr)
Other versions
EP1144851B1 (en
Inventor
Rainer Haeberer
Wolfgang Fleiner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1144851A1 publication Critical patent/EP1144851A1/en
Application granted granted Critical
Publication of EP1144851B1 publication Critical patent/EP1144851B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • 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
    • 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
    • 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
    • F02M37/00—Apparatus or systems for feeding liquid fuel from storage containers to carburettors or fuel-injection apparatus; Arrangements for purifying liquid fuel specially adapted for, or arranged on, internal-combustion engines
    • F02M37/0047—Layout or arrangement of systems for feeding fuel

Definitions

  • the invention relates to a fuel injection system, in particular a common rail system, for supplying fuel to internal combustion engines, in particular diesel engines for commercial vehicles, with a low-pressure circuit in which at least one low-pressure feed pump delivers fuel from a fuel tank to a high-pressure pump, which delivers the high-pressure fuel to a central one High-pressure fuel reservoir promotes.
  • Air is drawn in and compressed in diesel engines. At the end of the compression stroke, high-pressure fuel is injected into the combustion chamber, causing the mixture of air and fuel to self-ignite.
  • the high pressure pump conveys the fuel to be injected from the fuel tank to the central high pressure fuel reservoir, which is referred to as the common rail, with the aid of the prefeed pump.
  • Fuel lines lead from the rail to the individual injectors, which are assigned to the cylinders of the internal combustion engine.
  • the injectors are operated individually by the engine electronics controlled to inject fuel into the combustion chamber of the internal combustion engine.
  • the low pressure circuit When the fuel tank is run dry or after service work, the low pressure circuit is filled with air.
  • the air in the low-pressure circuit must be conveyed through the high-pressure pump into the high-pressure fuel reservoir against the opening pressure (approx. 1.5 bar) of the suction valve of the high-pressure pump. From there, the air can escape via a return line. This venting against the opening pressure of the suction valve takes a very long time with conventional low-pressure feed pumps.
  • Low pressure feed pumps with a larger delivery volume can be used. Such low-pressure feed pumps would, however, be greatly oversized for normal operation. As a result, the fuel flow supplied by such a low-pressure feed pump would have to be throttled in normal operation.
  • the object of the invention is to simplify the venting of the low pressure circuit of a conventional fuel injection system.
  • the fuel injection system according to the invention should be simple in construction and inexpensive to manufacture.
  • the object is in a fuel injection system, in particular a common rail system, for supplying fuel to internal combustion engines, in particular diesel engines of commercial vehicles, with a low-pressure circuit in which at least one low-pressure feed pump delivers fuel from a fuel tank to a high-pressure pump, which pumps the high-pressure fuel into one central
  • Fuel high-pressure accumulator promotes, solved in that a device is provided to specifically reduce the pressure in the low pressure circuit.
  • a special embodiment of the invention is characterized in that the low-pressure circuit is connected to the tank via a return line in which a throttle is provided.
  • the low pressure circuit is vented into the tank via the throttle. This has the advantage that no great back pressure has to be overcome when venting.
  • a further special embodiment of the invention is characterized in that the throttle is integrated in an overflow valve which is provided in the return line.
  • the throttle can e.g. in the form of a specifically leaky valve seat or as an additional throttle bore.
  • the integration of the throttle in the overflow valve saves costs.
  • a further special embodiment of the invention is characterized in that a vent hole with a vent screw is arranged at the highest point of the low pressure circuit in the installed state, in particular in a metering unit for the high pressure pump.
  • the air in the low-pressure circuit can escape to the atmosphere via the manually operated vent screw.
  • a further special embodiment of the invention is characterized in that the bleed screw has a flattened area in the thread area, which allows fuel to pass through the bleed hole if the bleed screw is slightly turned. In this way, an uncontrolled splashing out of the fuel at the beginning of the ventilation process can be avoided.
  • a further special embodiment of the invention is characterized in that the high-pressure pump is equipped with a metering unit which has a solenoid valve which, in the energized state, connects the low-pressure circuit and a return to the
  • the solenoid valve is normally closed when the internal combustion engine is started. If the solenoid valve is briefly energized when venting, the air in the low-pressure circuit can escape into the tank.
  • a hydraulic circuit diagram of a fuel injection system according to the invention is shown in the attached figure.
  • a fuel tank 1 fuel passes through a line 2 into a heat sink 3. From the heat sink 3, the fuel reaches a hand pump 5 via a line 4.
  • a check valve 6 is connected in parallel with the hand pump 5. The check valve 6 forms a bypass, which is opened, for example, when the hand pump 5 is defective or blocked.
  • a mechanically driven pre-feed pump 7 is arranged in line 4. Parallel to the mechanically driven pre-feed pump 7 are two check valves 38 and 39 arranged in opposite directions. The check valves 38 and 39 ensure that the pre-feed pump 7 is bypassed at a certain pressure difference.
  • a fuel filter 8 with a water separator is arranged in line 4.
  • a bypass line (not shown) with a check valve can be connected in parallel with the fuel filter 8.
  • the fuel delivered from the fuel tank 1 by the hand pump 5 or by the mechanically or electrically driven prefeed pump 7 passes via line 4 and line 9 to a high-pressure pump 10.
  • the high-pressure pump 10 comprises two high-pressure pump elements 11 and 12, in which the one of the Pre-feed pump 7 or the hand pump 5 is supplied with high pressure fuel.
  • the high-pressure lines 13 and 14 connect the high-pressure pump elements 11 and 12 to a central high-pressure fuel store 17.
  • Arrows 18, which emanate from the high-pressure fuel store 17, indicate a connection to the individual (not shown) injectors of the internal combustion engine to be supplied.
  • a flow control valve 19 is arranged in line 9, as described, for example, in DE 197 25 472. Via the quantity control valve 19, the line 9 can be connected to a return line 24 which opens into the fuel tank.
  • the line 4 is also connected to a line 20 in which a throttle 21 is arranged.
  • the line 20 can be connected to the return line 24 via a 2/2 way solenoid valve 22. If the solenoid valve 22 is briefly opened via a control unit (not shown), air which is possibly in the low-pressure circuit can escape into the fuel tank 1 via the line 20 and the return line 24.
  • a line 25 in which is a check valve 26 is connected to the return line 24.
  • a throttle 27 is connected in parallel with the check valve 26, via which air which may be present in the low-pressure circuit can escape into the fuel tank 1.
  • the line 4 is connected to a line 34 which opens into a vessel 35.
  • the line 34 indicates a vent hole (not shown) which can be closed by a vent screw.
  • the quantity control valve 19 and the 2/2-way solenoid valve 22 form a metering unit for the high-pressure element 12. Such a metering unit is also required for the high-pressure element 11, but this is not shown for reasons of clarity.

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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)

Abstract

The invention relates to a fuel injection system, especially a common rail system, for supplying fuel in internal combustion engines, especially diesel engines of commercial vehicles. The inventive system comprises a low pressure circuit (1-9), wherein at least one low pressure feed pump (5, 7) supplies fuel from a fuel tank (1) to a high pressure pump (10) which conveys the fuel that is impinged upon with high pressure to a central high pressure storage device (17) for fuel. The aim of the invention is to simplify ventilation of the low pressure circuit. A device (22; 25, 27; 34, 35) is provided for reducing the pressure in the low pressure circuit (1-9).

Description

KraftstoffeinspritzsvstemKraftstoffeinspritzsvstem
Stand der TechnikState of the art
Die Erfindung betrifft ein Kraftstoffeinspritzsystem, insbesondere Common-Rail-System, zur Kraftstoffversorgung von Brennkraftmaschinen, insbesondere Dieselmotoren von Nutzkraftwagen, mit einem Niederdruckkreislauf, in dem mindestens eine Niederdruckförderpumpe Kraftstoff aus einem Kraftstofftank zu einer Hochdruckpumpe liefert, die den mit Hochdruck beaufschlagten Kraftstoff in einen zentralen Kraftstoffhochdruckspeicher fördert .The invention relates to a fuel injection system, in particular a common rail system, for supplying fuel to internal combustion engines, in particular diesel engines for commercial vehicles, with a low-pressure circuit in which at least one low-pressure feed pump delivers fuel from a fuel tank to a high-pressure pump, which delivers the high-pressure fuel to a central one High-pressure fuel reservoir promotes.
In Dieselmotoren wird Luft angesaugt und verdichtet. Am Ende des Verdichtungshubes wird mit Hochdruck beaufschlagter Kraftstoff in den Verbrennungsraum eingespritzt, wodurch sich das Gemisch aus Luft und Kraftstoff selbst entzündet.Air is drawn in and compressed in diesel engines. At the end of the compression stroke, high-pressure fuel is injected into the combustion chamber, causing the mixture of air and fuel to self-ignite.
In Common-Rail-Einspritzsystemen fördert die Hochdruckpumpe, unter Zuhilfenahme der Vorförderpumpe , den einzuspritzenden Kraftstoff aus dem Kraftstofftank in den zentralen Kraftstoffhochdruckspeicher, der als Common-Rail bezeichnet wird. Von dem Rail führen Kraftstoffleitungen zu den einzelnen Injektoren, die den Zylindern der Brennkraftmaschine zugeordnet sind. Die Injektoren werden in Abhängigkeit von den Betriebsparametern der Brennkraft aschine einzeln von der Motorelektronik angesteuert, um Kraftstoff in den Brennraum der Brennkraftmaschine einzuspritzen .In common rail injection systems, the high pressure pump conveys the fuel to be injected from the fuel tank to the central high pressure fuel reservoir, which is referred to as the common rail, with the aid of the prefeed pump. Fuel lines lead from the rail to the individual injectors, which are assigned to the cylinders of the internal combustion engine. Depending on the operating parameters of the internal combustion engine, the injectors are operated individually by the engine electronics controlled to inject fuel into the combustion chamber of the internal combustion engine.
Wenn der Kraftstofftank leergefahren wird oder nach Servicearbeiten ist der Niederdruckkreislauf mit Luft gefüllt. Bei herkömmlichen Kraftstoffeinspritzsystemen muß die in dem Niederdruckkreislauf befindliche Luft gegen den Öffnungsdruck (ca. 1,5 bar) des Saugventils der Hochdruckpumpe durch die Hochdruckpumpe hindurch in den Kraftstoffhochdruckspeicher gefördert werden. Von dort kann die Luft dann über eine Rücklaufleitung entweichen. Diese Entlüftung gegen den Öffnungsdruck des Saugventils dauert mit herkömmlichen Niederdruckförderpumpen sehr lange.When the fuel tank is run dry or after service work, the low pressure circuit is filled with air. In conventional fuel injection systems, the air in the low-pressure circuit must be conveyed through the high-pressure pump into the high-pressure fuel reservoir against the opening pressure (approx. 1.5 bar) of the suction valve of the high-pressure pump. From there, the air can escape via a return line. This venting against the opening pressure of the suction valve takes a very long time with conventional low-pressure feed pumps.
Zur Beschleunigung des Entlüftungsvorganges könntenCould accelerate the venting process
Niederdruckförderpumpen mit einem größeren Fördervolumen eingesetzt werden. Derartige Niederdruckförderpumpen wären jedoch für den normalen Betrieb stark überdimensioniert. Demzufolge müßte der von einer derartigen Niederdruckförderpumpe gelieferte Kraftstoffström im normalen Betrieb abgedrosselt werden.Low pressure feed pumps with a larger delivery volume can be used. Such low-pressure feed pumps would, however, be greatly oversized for normal operation. As a result, the fuel flow supplied by such a low-pressure feed pump would have to be throttled in normal operation.
Aufgabe der Erfindung ist es, das Entlüften des Niederdruckkreislaufs eines herkömmlichen Kraftstoffeinspritzsystems zu vereinfachen. Darüber hinaus soll das erfindungsgemäße Kraftstoffeinspritzsystem einfach aufgebaut und kostengünstig herstellbar sein.The object of the invention is to simplify the venting of the low pressure circuit of a conventional fuel injection system. In addition, the fuel injection system according to the invention should be simple in construction and inexpensive to manufacture.
Die Aufgabe ist bei einem Kraftstoffeinspritzsystem, insbesondere Common-Rail-System, zur Kraftstoffversorgung von Brennkraftmaschinen, insbesondere Dieselmotoren von Nutzkraftwagen, mit einem Niederdruckkreislauf, in dem mindestens eine Niederdruckförderpumpe Kraftstoff aus einem Kraftstofftank zu einer Hochdruckpumpe liefert, die den mit Hochdruck beaufschlagten Kraftstoff in einen zentralenThe object is in a fuel injection system, in particular a common rail system, for supplying fuel to internal combustion engines, in particular diesel engines of commercial vehicles, with a low-pressure circuit in which at least one low-pressure feed pump delivers fuel from a fuel tank to a high-pressure pump, which pumps the high-pressure fuel into one central
Kraftstoffhochdruckspeicher fördert, dadurch gelöst, dass eine Einrichtung vorgesehen ist, um den Druck in dem Niederdruckkreislauf gezielt abzubauen.Fuel high-pressure accumulator promotes, solved in that a device is provided to specifically reduce the pressure in the low pressure circuit.
Vorteile der ErfindungAdvantages of the invention
Dadurch kann der Druck im Niederdruckkreislauf beim Entlüften abgesenkt werden. Das liefert den Vorteil, dass die in dem Niederdruckkreislauf befindliche Luft mit einer herkömmlichen, nicht überdimensionierten Niederdruckförderpumpe in einer vertretbaren Zeit verdrängt werden kann .This allows the pressure in the low-pressure circuit to be reduced when venting. This provides the advantage that the air in the low-pressure circuit can be displaced in a reasonable time using a conventional, not oversized, low-pressure feed pump.
Eine besondere Ausführungsart der Erfindung ist dadurch gekennzeichnet, dass der Niederdruckkreislauf über eine Rücklaufleitung, in der eine Drossel vorgesehen ist, mit dem Tank verbunden ist. Über die Drossel erfolgt das Entlüften des Niederdruckkreislaufes in den Tank. Das hat den Vorteil, dass beim Entlüften kein großer Gegendruck überwunden werden muß.A special embodiment of the invention is characterized in that the low-pressure circuit is connected to the tank via a return line in which a throttle is provided. The low pressure circuit is vented into the tank via the throttle. This has the advantage that no great back pressure has to be overcome when venting.
Eine weitere besondere Ausführungsart der Erfindung ist dadurch gekennzeichnet, dass die Drossel in ein Überströmventil integriert ist, das in der Rücklaufleitung vorgesehen ist. Die Drossel kann z.B. in Form eines gezielt undichten Ventilsitzes oder als zusätzliche Drosselbohrung dargestellt werden. Durch die Integration der Drossel in das Überströmventil werden Kosten eingespart.A further special embodiment of the invention is characterized in that the throttle is integrated in an overflow valve which is provided in the return line. The throttle can e.g. in the form of a specifically leaky valve seat or as an additional throttle bore. The integration of the throttle in the overflow valve saves costs.
Eine weitere besondere Ausführungsart der Erfindung ist dadurch gekennzeichnet, dass an der im eingebauten Zustand am höchsten gelegenen Stelle des Niederdruckkreislaufs , insbesondere in einer Zumesseinheit für die Hochdruckpumpe, eine Entlüftungsbohrung mit einer Entlüftungsschraube angeordnet ist . Über die manuell betätigbare Entlüftungsschraube kann die im Niederdruckkreislauf befindliche Luft in die Atmosphäre entweichen. Diese Ausführungsart hat den Vorteil, dass sie aufgrund ihrer Einfachheit besonders kostengünstig zu realisieren ist . Die Entlüftungsbohrung ist so anzuordnen, dass ggf. austretender Kraftstoff in einem Gefäß aufgefangen werden kan .A further special embodiment of the invention is characterized in that a vent hole with a vent screw is arranged at the highest point of the low pressure circuit in the installed state, in particular in a metering unit for the high pressure pump. The air in the low-pressure circuit can escape to the atmosphere via the manually operated vent screw. This The design has the advantage that it is particularly cost-effective to implement due to its simplicity. The vent hole must be arranged so that any escaping fuel can be collected in a vessel.
Eine weitere besondere Ausführungsart der Erfindung ist dadurch gekennzeichnet, dass die Entlüftungsschraube im Gewindebereich eine Abflachung aufweist, die den Durchtritt von Kraftstoff durch die Entlüftungsbohrung ermöglicht, wenn die Entlüftungsschraube geringfügig verdreht wird. Dadurch kann ein unkontrolliertes Herausspritzen des Kraftstoffs zu Beginn des Entlüftungsvorgangs vermieden werden.A further special embodiment of the invention is characterized in that the bleed screw has a flattened area in the thread area, which allows fuel to pass through the bleed hole if the bleed screw is slightly turned. In this way, an uncontrolled splashing out of the fuel at the beginning of the ventilation process can be avoided.
Eine weitere besondere Ausführungsart der Erfindung ist dadurch gekennzeichnet, dass die Hochdruckpumpe mit einer Zumesseinheit ausgestattet ist, die ein Magnetventil aufweist, das im bestromten Zustand eine Verbindung zwischen dem Niederdruckkreislauf und einem Rücklauf in denA further special embodiment of the invention is characterized in that the high-pressure pump is equipped with a metering unit which has a solenoid valve which, in the energized state, connects the low-pressure circuit and a return to the
Tank freigibt . Normalerweise ist das Magnetventil beim Starten der Brennkraftmaschine geschlossen. Wenn das Magnetventil beim Entlüften kurzzeitig bestromt wird, kann die im Niederdruckkreislauf befindliche Luft in den Tank entweichen.Releases tank. The solenoid valve is normally closed when the internal combustion engine is started. If the solenoid valve is briefly energized when venting, the air in the low-pressure circuit can escape into the tank.
Weitere Vorteile, Merkmale und Einzelheiten der Erfindung ergeben sich aus der nachfolgenden Beschreibung, in der unter Bezugnahme auf die Zeichnung drei Ausführungsbeispiele der Erfindung im einzelnen beschrieben sind. Dabei können die in den Ansprüchen und in der Beschreibung erwähnten Merkmale jeweils einzeln für sich oder in beliebiger Kombination erfindungswesentlich sein. ZeichnungFurther advantages, features and details of the invention emerge from the following description, in which three exemplary embodiments of the invention are described in detail with reference to the drawing. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination. drawing
In der beiliegenden Figur ist ein Hydraulikschaltplan eines erfindungsgemäßen Kraftstoffeinspritzsystems dargestellt.A hydraulic circuit diagram of a fuel injection system according to the invention is shown in the attached figure.
Beschreibung der AusführungsbeispieleDescription of the embodiments
Der Einfachheit halber sind in der beiliegenden Figur drei verschiedene Ausführungsformen der vorliegenden Erfindung beispielhaft dargestellt. Im folgenden wird zunächst das Hydraulikschaltbild erläutert. Im Anschluß daran wird auf die drei Ausführungsformen der Erfindung im Einzelnen eingegangen.For the sake of simplicity, three different embodiments of the present invention are exemplified in the accompanying figure. The hydraulic circuit diagram is first explained below. The three embodiments of the invention are discussed in detail below.
Aus einem Kraftstofftank 1 gelangt Kraftstoff durch eine Leitung 2 in einen Kühlkörper 3. Von dem Kühlkörper 3 gelangt der Kraftstoff über eine Leitung 4 zu einer Handpumpe 5. Parallel zu der Handpumpe 5 ist ein Rückschlagventil 6 geschaltet. Das Rückschlagventil 6 bildet einen Bypass, der beispielsweis dann geöffnet wird, wenn die Handpumpe 5 defekt oder verstopft ist.From a fuel tank 1, fuel passes through a line 2 into a heat sink 3. From the heat sink 3, the fuel reaches a hand pump 5 via a line 4. A check valve 6 is connected in parallel with the hand pump 5. The check valve 6 forms a bypass, which is opened, for example, when the hand pump 5 is defective or blocked.
Im Anschluß an die Handpumpe 5 ist in der Leitung 4 eine mechanisch angetriebene Vorförderpumpe 7 angeordnet . Parallel zu der mechanisch angetriebenen Vorförderpumpe 7 sind zwei gegensinnig angeordnete Rückschlagventile 38 und 39. Die Rückschlagventile 38 und 39 sorgen dafür, dass die Vorförderpumpe 7 bei einer bestimmten Druckdifferenz umgangen wird.Following the hand pump 5, a mechanically driven pre-feed pump 7 is arranged in line 4. Parallel to the mechanically driven pre-feed pump 7 are two check valves 38 and 39 arranged in opposite directions. The check valves 38 and 39 ensure that the pre-feed pump 7 is bypassed at a certain pressure difference.
Im Anschluß an die Vorförderpumpe 7 ist in der Leitung 4 ein Kraftstofffilter 8 mit Wasserabscheider angeordnet . Parallel zu dem Kraftstofffilter 8 kann eine (nicht dargestellte) Bypassleitung mit einem Rückschlagventil geschaltet sein. Der von der Handpumpe 5 bzw. von der mechanisch oder elektrisch angetriebenen Vorförderpumpe 7 aus dem Kraftstofftank 1 geförderte Kraftstoff gelangt über die Leitung 4 und eine Leitung 9 zu einer Hochdruckpumpe 10. Die Hochdruckpumpe 10 umfasst zwei Hochdruckpumpenelemente 11 und 12, in denen der von der Vorförderpumpe 7 bzw. der Handpumpe 5 gelieferte Kraftstoff mit Hochdruck beaufschlagt wird.Following the pre-feed pump 7, a fuel filter 8 with a water separator is arranged in line 4. A bypass line (not shown) with a check valve can be connected in parallel with the fuel filter 8. The fuel delivered from the fuel tank 1 by the hand pump 5 or by the mechanically or electrically driven prefeed pump 7 passes via line 4 and line 9 to a high-pressure pump 10. The high-pressure pump 10 comprises two high-pressure pump elements 11 and 12, in which the one of the Pre-feed pump 7 or the hand pump 5 is supplied with high pressure fuel.
Von den Hochdruckpumpenelementen 11 und 12 gehen Hochdruckleitungen 13 und 14 aus, in denen Rückschlagventile 15 und 16 angeordnet sind. Die Hochdruckleitungen 13 und 14 verbinden die Hochdruckpumpenelemente 11 und 12 mit einem zentralen Kraftstoffhochdruckspeicher 17. Durch Pfeile 18, die von dem Kraftstoffhochdruckspeicher 17 ausgehen, ist eine Verbindung zu den einzelnen (nicht dargestellten) Injektoren der zu versorgenden Brennkraftmaschine angedeutet .High-pressure lines 13 and 14, in which check valves 15 and 16 are arranged, start from the high-pressure pump elements 11 and 12. The high-pressure lines 13 and 14 connect the high-pressure pump elements 11 and 12 to a central high-pressure fuel store 17. Arrows 18, which emanate from the high-pressure fuel store 17, indicate a connection to the individual (not shown) injectors of the internal combustion engine to be supplied.
In der Leitung 9 ist ein Mengenregelventil 19 angeordnet, wie es bspw. in der DE 197 25 472 beschrieben ist. Über das Mengenregelventil 19 kann die Leitung 9 mit einer Rücklaufleitung 24 verbunden werden, die in den Kraftstofftank mündet.A flow control valve 19 is arranged in line 9, as described, for example, in DE 197 25 472. Via the quantity control valve 19, the line 9 can be connected to a return line 24 which opens into the fuel tank.
Die Leitung 4 steht außerdem mit einer Leitung 20 in Verbindung, in der eine Drossel 21 angeordnet ist. Die Leitung 20 ist über ein 2/2 -Wegemagnetventil 22 mit der Rücklaufleitung 24 verbindbar. Wenn das Magnetventil 22 über ein (nicht dargestelltes) Steuergerät kurzzeitig geöffnet wird, kann evtl. im Niederdruckkreislauf befindliche Luft über die Leitung 20 und die Rücklaufleitung 24 in den Kraftstofftank 1 entweichen .The line 4 is also connected to a line 20 in which a throttle 21 is arranged. The line 20 can be connected to the return line 24 via a 2/2 way solenoid valve 22. If the solenoid valve 22 is briefly opened via a control unit (not shown), air which is possibly in the low-pressure circuit can escape into the fuel tank 1 via the line 20 and the return line 24.
Darüber hinaus ist die Leitung 4 über eine Leitung 25, in der ein Rückschlagventil 26 angeordnet ist, mit der Rücklaufleitung 24 verbunden. Gemäß einer zweiten Ausführungsform der Erfindung ist parallel zu dem Rückschlagventil 26 eine Drossel 27 geschaltet, über die evtl. im Niederdruckkreislauf vorhandene Luft in den Kraftstofftank 1 entweichen kann.In addition, the line 4 via a line 25, in which is a check valve 26 is connected to the return line 24. According to a second embodiment of the invention, a throttle 27 is connected in parallel with the check valve 26, via which air which may be present in the low-pressure circuit can escape into the fuel tank 1.
Schließlich steht die Leitung 4 gemäß einer dritten Ausführungsform der Erfindung mit einer Leitung 34 in Verbindung, die in ein Gefäß 35 mündet. Die Leitung 34 deutet eine (nicht dargestellte) Entlüftungsbohrung an, die durch eine Entlüftungsschraube verschließbar ist.Finally, according to a third embodiment of the invention, the line 4 is connected to a line 34 which opens into a vessel 35. The line 34 indicates a vent hole (not shown) which can be closed by a vent screw.
Schließlich wird noch darauf hingewiesen, dass der Kraftstoffhochdruckspeicher 17 über eine RücklaufleitungFinally, it is pointed out that the high-pressure fuel reservoir 17 via a return line
30, in der ein Rückschlagventil 31 angeordnet ist, mit dem Kühlkörper 3 verbunden ist.30, in which a check valve 31 is arranged, is connected to the heat sink 3.
Das Mengenregelventil 19 und das 2/2-Wegemagnetventil 22 bilden eine Zumesseinheit für das Hochdruckelement 12. FÜr das Hochdruckelement 11 ist auch eine solche Zumesseinheit erforderlich, die jedoch aus Gründen der Übersichtlichkeit nicht dargestellt ist. The quantity control valve 19 and the 2/2-way solenoid valve 22 form a metering unit for the high-pressure element 12. Such a metering unit is also required for the high-pressure element 11, but this is not shown for reasons of clarity.

Claims

AnsprücheExpectations
l. Kraftstoffeinspritzsystem, insbesondere Common-Rail- System, zur Kraftstoffversorgung von Brennkraftmaschinen, insbesondere Dieselmotoren von Nutzkraftwagen, mit einem Niederdruckkreislauf (1 - 9), in dem mindestens eine Niederdruckförderpumpe (5, 7) Kraftstoff aus einem Kraftstofftank (1) zu einerl. Fuel injection system, in particular common rail system, for supplying fuel to internal combustion engines, in particular diesel engines of commercial vehicles, with a low-pressure circuit (1-9) in which at least one low-pressure feed pump (5, 7) forms fuel from a fuel tank (1)
Hochdruckpumpe (10) liefert, die den mit Hochdruck beaufschlagten Kraftstoff in einen zentralen Kraftstoffhochdruckspeicher (17) fördert, dadurch, gekennzeichnet, dass eine Einrichtung (22; 25, 27; 34, 35) vorgesehen ist, um den Druck in demHigh-pressure pump (10) delivers, which conveys the high-pressure fuel into a central high-pressure fuel store (17), characterized in that a device (22; 25, 27; 34, 35) is provided to the pressure in the
Niederdruckkreislauf (1 - 9) gezielt abzubauen.Reduce the low-pressure circuit (1 - 9) in a targeted manner.
2. Kraftstoffeinspritzsystem nach Anspruch 1, dadurch gekennzeichnet, dass der Niederdruckkreislauf (1 - 9) über eine Rücklaufleitung (24, 25), in der eine2. Fuel injection system according to claim 1, characterized in that the low-pressure circuit (1-9) via a return line (24, 25) in which one
Drossel (27) vorgesehen ist, mit dem Tank (1) verbunden ist.Throttle (27) is provided, is connected to the tank (1).
3. Kraftstoffeinspritzsystem nach Anspruch 2, dadurch gekennzeichnet, dass die Drossel (27) in ein3. Fuel injection system according to claim 2, characterized in that the throttle (27) in one
Überströmventil (26) integriert ist, das in der Rücklaufleitung (25) vorgesehen ist.Overflow valve (26) is integrated, which is provided in the return line (25).
4. Kraftstoffeinspritzsystem nach Anspruch 1, dadurch gekennzeichnet, dass an der im eingebauten Zustand am höchsten gelegenen Stelle des Niederdruckkreislaufs (1 - 9) , insbesondere in einer Zumesseinheit für die Hochdruckpumpe (10) , eine Entlüf ungsbohrung (34) mit einer Entlüftungsschraube angeordnet ist.4. The fuel injection system according to claim 1, characterized in that at the highest point of the low-pressure circuit (1 - 9), in particular in a metering unit for the high pressure pump (10), a vent hole (34) is arranged with a vent screw.
5. Kraftstoffeinspritzsystem nach Anspruch 4, dadurch gekennzeichnet, dass die Entlüftungsschraube im Gewindebereich eine Abflachung aufweist, die den Druchtritt von Kraftstoff durch die Entlüftungsbohrung (34) ermöglicht, wenn die Entlüftungsschraube geringfügig verdreht wird.5. Fuel injection system according to claim 4, characterized in that the vent screw has a flattened portion in the threaded region, which enables fuel to pass through the vent hole (34) when the vent screw is rotated slightly.
6. Kraftstoffeinspritzsystem nach Anspruch 1, dadurch gekennzeichnet, dass die Hochdruckpumpe (10) mit einer Zumesseinheit (19) ausgestattet ist, die ein Magnetventil (22) aufweist, das im bestromten Zustand eine Verbindung zwischen dem Niederdruckkreislauf (1 - 9) und einem Rücklauf (24) in den Tank (1) freigibt. 6. Fuel injection system according to claim 1, characterized in that the high pressure pump (10) is equipped with a metering unit (19) which has a solenoid valve (22) which, when energized, a connection between the low pressure circuit (1-9) and a return (24) in the tank (1) releases.
EP00988551A 1999-11-13 2000-10-27 Fuel injection system Expired - Lifetime EP1144851B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19954695 1999-11-13
DE19954695A DE19954695A1 (en) 1999-11-13 1999-11-13 Fuel injection system
PCT/DE2000/003797 WO2001036809A1 (en) 1999-11-13 2000-10-27 Fuel injection system

Publications (2)

Publication Number Publication Date
EP1144851A1 true EP1144851A1 (en) 2001-10-17
EP1144851B1 EP1144851B1 (en) 2005-12-07

Family

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EP00988551A Expired - Lifetime EP1144851B1 (en) 1999-11-13 2000-10-27 Fuel injection system

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US (1) US6564776B1 (en)
EP (1) EP1144851B1 (en)
JP (1) JP2003515033A (en)
DE (2) DE19954695A1 (en)
WO (1) WO2001036809A1 (en)

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Also Published As

Publication number Publication date
DE19954695A1 (en) 2001-05-23
EP1144851B1 (en) 2005-12-07
JP2003515033A (en) 2003-04-22
WO2001036809A1 (en) 2001-05-25
DE50011815D1 (en) 2006-01-12
US6564776B1 (en) 2003-05-20

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