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EP0610585B1 - Fuel injection device with pilot- and main-injection - Google Patents

Fuel injection device with pilot- and main-injection Download PDF

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Publication number
EP0610585B1
EP0610585B1 EP93120308A EP93120308A EP0610585B1 EP 0610585 B1 EP0610585 B1 EP 0610585B1 EP 93120308 A EP93120308 A EP 93120308A EP 93120308 A EP93120308 A EP 93120308A EP 0610585 B1 EP0610585 B1 EP 0610585B1
Authority
EP
European Patent Office
Prior art keywords
fuel
injection
control piston
pressure
pump
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.)
Expired - Lifetime
Application number
EP93120308A
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German (de)
French (fr)
Other versions
EP0610585A1 (en
Inventor
Helmut Dipl.-Ing. Priesner
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.)
MAN Truck and Bus Osterreich AG
Original Assignee
Steyr Nutzfahrzeuge AG
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Publication date
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Publication of EP0610585A1 publication Critical patent/EP0610585A1/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
    • F02M43/00—Fuel-injection apparatus operating simultaneously on two or more fuels, or on a liquid fuel and another liquid, e.g. the other liquid being an anti-knock additive
    • F02M43/04—Injectors peculiar thereto
    • 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
    • F02M43/00—Fuel-injection apparatus operating simultaneously on two or more fuels, or on a liquid fuel and another liquid, e.g. the other liquid being an anti-knock additive
    • 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
    • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • 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
    • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
    • F02M45/02—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts
    • F02M45/04—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship with each cyclic delivery being separated into two or more parts with a small initial part, e.g. initial part for partial load and initial and main part for full load
    • F02M45/08—Injectors peculiar thereto
    • F02M45/086—Having more than one injection-valve controlling discharge orifices
    • 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
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/44—Valves, e.g. injectors, with valve bodies arranged side-by-side
    • 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
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/95—Fuel injection apparatus operating on particular fuels, e.g. biodiesel, ethanol, mixed fuels
    • F02M2200/956—Ethanol

Definitions

  • the invention relates to a fuel injection device for a pre-injection and main injection via a two-needle injection valve into a combustion chamber of an internal combustion engine, with an injection pump with cam-controlled pump pistons that can be rotated for power control, the pump chambers of which can be filled with fuel via a laterally opening control bore and sent to the a valve spring-loaded in the closing direction is connected on the outlet side.
  • the invention is based on a prior art according to DE 29 24 128 A1.
  • This document discloses an injection device for a pre-injection of ignitable fuel and a main injection of ignition-inert fuel, via a two-needle injection valve, in which both valve needles are arranged coaxially one inside the other, which also means a correspondingly adapted supply of the different fuels via suitably designed conduction paths in view means the timing of the pre and main injection.
  • This solution poses problems or has certain disadvantages, which are discussed in more detail below.
  • the injection pump must always be operated with the slow ignition fuel. This can lead to problems because, for example, ethanol has a low lubricity or, if a water-based emulsion is used as fuel, this can cause corrosion.
  • the stand pressure in the injection line must be very low and constant, preferably equal to the vapor pressure. In practice, this requirement cannot be met by the constant pressure valve according to FIG. 2. 3 and 4, this requirement can only be met by overloading the injection line, so that the injection line is generally not completely filled even after the main injection fuel has been supplied. This fact causes a number of known disadvantages, such as cavitation, spread of injection quantity and start, low injection pressure.
  • the inventive division of the two-needle injection valve into two nozzle needles installed next to one another parallel to the axis allows each of them to be used Comparatively simple and the opening pressure can be set exactly defined via the respectively assigned compression spring. Furthermore, this allows a favorable design of the line paths for the supply of the pre-injection fuel to the nozzle antechamber of the pre-injection needle and a simple installation of the necessary check valve.
  • the arrangement of the nozzle needles according to the invention also makes it easy to accommodate the control piston according to the invention as part of the injection control.
  • each pump chamber of the injection pump is followed by a pump outlet chamber receiving a pressure valve and a compression spring and an injection line connected to a supply channel inside the injection valve.
  • Each pressure valve acts as a pressure piston with each pump piston stroke, pushing out the fuel given in the subsequent conduit paths and at the same time shutting off a filling hole that opens laterally into the pump outlet space, via which, after each main injection process and return of the pressure valve to its closed position, the resulting cavity in the downstream lines can be refilled with main injection fuel from a low-pressure feed device.
  • the injection pump acting in this way, the pressure valves and the control pistons in the two-needle injection valves, in conjunction with the further construction of the latter, enable exact fulfillment of the tasks set, namely an exact quantitative dosage of both the pre- and main injection fuel and a precisely defined time Sequence of the pre and main injection.
  • the fuel injection device has an injection pump 1 with pump pistons 2 controlled by cams (not shown), each of which has conventional control grooves 3, 4 and oblique control edges 5 and can be rotated by a control device (also not shown) for power control.
  • a pump outlet chamber 8 is connected to each of the pump chambers 7, which can be filled with fuel via a laterally opening control bore 6, and an injection line 11, which is connected to an internally of a two-needle injection valve 9, is connected to this. If the two-needle injection valve 9 is combined with the injection pump 1 to form a pump nozzle member, the injection line 11 is omitted.
  • connection bore 12 between each pump chamber 7 and pump outlet chamber 8 is provided on the rear with a conical extension 13, which serves as a seat serves for a pressure valve 14 installed in the pump outlet chamber 8 with little leakage, which is acted upon in the closing direction by a compression spring 15 likewise installed in the pump outlet chamber 8.
  • the injection pump according to the invention only serves to build up pressure and to push out the amount of main injection fuel that is to be injected, which fuel is successively fed to the line paths 8, 11, 10 connected to the pressure valve 14.
  • Each pressure valve 14 acts as a pressure piston during the pump piston stroke, which pushes out the fuel behind it due to its stroke movement and at the same time blocks a filling bore 16 that opens laterally into the pump outlet space 8, via which, after the completion of each main injection process and return of the pressure valve 14 into its closed position, thereby resulting cavity in said, downstream of the latter lines 8, 11, 10 from a low-pressure feed device 17 can be refilled with main injection fuel.
  • Each two-needle injection valve 9 assigned to a cylinder of the internal combustion engine has two nozzle needles installed axially parallel to one another, a pre-injection needle 18 and a main injection needle 19, each of which is acted upon in the closing direction by a compression spring 20 or 21 supported on a pressure plate and defining the opening pressure and in the closed position, supported on a seat 22 or 23, shut off the associated nozzle bores 24 or 25 or in the open position release the latter for injection.
  • the opening pressure of the pre-injection needle 18 is preferred lower, e.g. set to ⁇ 70% than that of the main injection needle 19, specifically by designing the compression springs 20, 21.
  • the opening pressure of the pre-injection needle 18 can be set to 200 bar and the opening pressure of the main injection needle to 300 bar. Depending on this opening pressure setting, there is a certain time offset between the start of the pre-injection and the main injection.
  • Each of the two nozzle needles 18, 19 has a front cylindrical section and a rear section which is larger in diameter, the transition surface 26 or 27 between the two needle sections being provided in the enlarged area of the associated nozzle antechamber 28 and 29, respectively forms the effective pressure area in the opening direction of the respective valve needle 18 or 19.
  • the nozzle antechamber 28 of the pre-injection needle 18 is from a low-pressure feed device via a valve-internal channel 30/1, 30/2, 30/3, 30/4 with a check valve 31 which is preferably installed as close as possible before its junction in the nozzle antechamber 28 and is only permeable in the feed direction 32 ago with pre-injection fuel.
  • the centerpiece of the fuel injection device is a control piston 33, which is installed in each two-needle injection valve 9 and is axially freely movable between two end positions, for an exact quantitative metering of the pre-injection fuel quantity and a precisely defined control of the pre-injection as well as a time offset at the beginning with or without Overlap controlled main injection is responsible.
  • This control piston 33 is in the region between the two valve needles 18, 19 preferably axially displaceably axially displaceably received in a receiving bore 34 which below - to form a control antechamber 35 - and further up, from which the bottom stop forming the bottom of the latter by about
  • the length of the control piston 33 spaced apart - to form a transfer space 36 - is correspondingly expanded and extends coaxially to the central, smaller-diameter feed channel 10, the transition from the latter to the receiving bore 34 being formed by an insert sleeve 37, the lower end face of which is the upper stop for the control piston 33 forms.
  • the control antechamber 35 of the control piston 33 is connected via a bore 38 to the nozzle antechamber 28 of the pre-injection needle.
  • the transfer chamber 36 is in turn connected to the nozzle antechamber 29 of the main injection needle, depending on the distance by cutting the same or via a bore.
  • control piston 33 is generally from its one, after the end of a pre-injection, given the lower end position by the low-pressure feed device 32 and its control antechamber 35 via the channel 38 from the nozzle antechamber 28 of the pre-injection needle 18 into its other, upper injection fuel End position displaceable, the feed channel during this upward movement 10 is closed.
  • control piston 33 can be moved downward in the case of a pressure build-up controlled on the pump piston side via the main injection fuel present in the feed channel 10, the pre-injection fuel present in its control antechamber 35 being displaced - due to the closed check valve 31 - by opening the pre-injection needle 18 and into the combustion chamber is injected, and after a certain distance from the control piston 33 the connection between the feed channel 10 and the transfer chamber 36 and thus the fuel path to the nozzle antechamber 29 of the main injection needle 19 is released, whereupon the latter is then raised by the pressure rise of the main injection fuel supplied on the pump piston side and the latter up to the pressure on the pump piston side is injected.
  • the pump piston 2 now moves upwards driven by a cam (not shown), it closes the control bore 6, as a result of which the pressure in the pump chamber 7 increases and the pressure valve 14 is raised against the force of the compression spring 15. After a short stroke, the pressure valve 14 closes the filling bore 16, whereupon the main injection fuel column in the subsequent line paths 8, 11, 10 is advanced by the further movement of the pressure valve 14, which acts as a pressure piston.
  • the injector-internal control piston 33 is shifted downward from its upper end position, whereby the pre-injection fuel 18 thus displaced from its control antechamber 35 raises the pre-injection needle 18 and then with further main-controlled injection fuel Downward movement of the control piston 33 up to its lower end position the amount of pre-injection fuel corresponding to this volume displacement is injected into the combustion chamber of the internal combustion engine via the nozzle bores 24. Since the pump piston-controlled pressure rises relatively quickly, only a small offset between the pre-injection and the main injection can be achieved in the embodiment of the control piston according to FIGS. 1 and 2.
  • the fuel provided for the pre-injection is refilled by the low-pressure feed device 32, specifically via the valve-internal line paths 30/1, 30/2, 30/3, 30/4 by opening the check valve 31 and filling the nozzle antechamber 28 of the pre-injection needle 18, the bore 38 and the control antechamber 35 of the control piston 33, as a result of which the piston 33 is moved from its lower stop position to its upper stop position with the supply channel 10 shut off.
  • the delivery pressure P2 of the low-pressure feed device 17 is set correspondingly higher than the delivery pressure P1 of the low-pressure feed device 32 and also in the line path between low-pressure feed device 32 and check valve 31 there is a throttle 39, the passage cross section of which is substantially smaller than that of another throttle 40, which is given in the line path between low-pressure feed device 17 and pump outlet space 8.
  • the throttle 39 is in particular given at the beginning of a two-needle injection valve 9, while the throttle 40 is installed in the filling bore 16 in particular at the entrance to the pump outlet space 8.
  • control piston 33 - as can be seen in FIG. 5 - has a blind hole 41 drilled from above and one of the latter Have circumferential leading, considerably smaller diameter transverse bore 42.
  • This is provided on the control piston 33 in such an axial relative position that, when the latter is in the upper end position, there is a throttled connection between the feed channel 10 and the transfer space 36 to the nozzle antechamber 29 of the main injection needle 19.
  • this transverse bore 42 is covered and thus closed by the receiving bore 34 after a short downward stroke of the control piston 33, so that the pilot injection can be controlled unhindered by its downward movement.
  • control piston 33 can also - as can be seen from FIG. 3 - be designed as a stepped piston.
  • the control piston 33 consists of two cylinder sections 33/1, 33/2 with different diameters, the smaller diameter (33/2) forming the lower control piston part, to which the receiving bore 34 is correspondingly adapted on the diameter side.
  • the latter is also expanded at the level of the transition of the two cylinder sections 33/1, 33/2 - when viewed in the lower stop position of the control piston 33 - by a leakage space 43, from which a leakage discharge duct 44 leads away.
  • control piston 33 is cylindrical with a flat upper end face. Furthermore, the receiving volume of the control antechamber 35 is expanded by a blind hole 45 drilled into the control piston 33 from below, which is connected at a certain point via a transverse bore 46 to the circumference of the control piston 33.
  • FIG. 4A shows the control piston 33 in its upper stop position, as is given at the beginning of the delivery stroke on the pump piston side.
  • the control piston moves downwards, as a result of which - while the connections between the feed channel 10 and the nozzle chamber 29 of the main injection needle 19 and between the control chamber 35 and the leakage chamber 47 are still closed Pressure in the nozzle antechamber 28 rises, the pre-injection needle 18 is raised and the pre-injection takes place via the nozzle bores 24.
  • the receiving bore 34 releases the transverse bore 46 - see the spool position shown in FIG. 4B.
  • Each of the two low-pressure feed devices 17, 32 has a feed pump 17/1 or 32/1 and a pressure relief valve 17/2 or 32/2, via which the feed pressure P1 of the feed pump 17/1 or P2 of the feed pump 32 / 1 is set to a range between approx. 2 to 4 bar.
  • the fuel injection device according to the invention can, regardless of its respective design, in principle either for pre-injection and main injection of the same fuel - see FIG. 1 - or for pre-injection of an ignitable fuel, in particular diesel fuel, and main injection of an ignitable fuel such as a diesel fuel-water emulsion or ethanol - see Fig. 2 - be used.
  • the two different fuels are provided in different storage tanks 49, 50 and are fed therefrom to the connected fuel paths by means of the respective low-pressure feed device 17 or 32.
  • the low-pressure feed device 32 also serves to supply the pump chambers 7 of the injection pump 1, each of which is connected via a line 51.
  • FIG. 1 the case of FIG.
  • the fuel used for pre-injection and main injection is provided in a storage tank 52, from which the pumps 17/1 and 32/1 of both low-pressure feed devices 17, 32 deliver fuel into the connected line paths.
  • the pump chambers 7 of the injection pump 1 can be supplied with fuel from the low-pressure feed device 17 via a branch line 53.

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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

Die Erfindung betrifft eine Kraftstoffeinspritzvorrichtung für eine Vor- und Haupteinspritzung über je ein Zwei-Nadel-Einspritzventil in einen Brennraum einer Brennkraftmaschine, mit einer Einspritzpumpe mit nockengesteuerten, für Leistungsregelung verdrehbaren Pumpenkolben, deren Pumpenräume jeweils über eine seitlich einmündende Steuerbohrung mit Kraftstoff füllbar und an die sich ausgangsseitig ein in Schließrichtung federbelastetes Ventil anschließt.The invention relates to a fuel injection device for a pre-injection and main injection via a two-needle injection valve into a combustion chamber of an internal combustion engine, with an injection pump with cam-controlled pump pistons that can be rotated for power control, the pump chambers of which can be filled with fuel via a laterally opening control bore and sent to the a valve spring-loaded in the closing direction is connected on the outlet side.

Die Erfindung geht aus von einem Stand der Technik gemäß der DE 29 24 128 A1. Diese Schrift offenbart eine Einspritzvorrichtung für eine Voreinspritzung von zündwilligem Kraftstoff und eine Haupteinspritzung von zündträgem Kraftstoff, über ein Zwei-Nadel-Einspritzventil, bei dem beide Ventilnadeln koaxial ineinander angeordnet sind, was auch eine entsprechend angepaßte Zuführung der verschiedenen Kraftstoffe über entsprechend ausgebildete Leitungswege im Hinblick auf den zeitlichen Ablauf der Vor- und Haupteinspritzung bedeutet. Diese Lösung wirft jedoch Probleme auf bzw. ist mit gewissen Nachteilen behaftet, auf die nachfolgend näher eingegangen ist. Die Einspritzpumpe muß immer mit dem zündträgen Kraftstoff betrieben werden. Dies kann deshalb zu Problemen führen, da zum Beispiel Äthanol eine geringe Schmierfähigkeit aufweist oder, wenn als Kraftstoff eine wasserhaltige Emulsion verwendet wird, dieser Korrosion verursachen kann. Darüber hinaus sind bei dieser bekannten Lösung ausgangs der Einspritzpumpe entweder Gleichdruckventile (Fig. 2), Drosselrückschlagventile (Fig. 3) oder Gleichraumventile (Fig. 4) vorgesehen, aufgrund derselben gewisse Probleme bei der Dosierung des geförderten Kraftstoffes auftreten. Soll die Dosierung desselben nur durch Druck und Querschnitt gesteuert werden, wie in der Beschreibung Seite 7 unten angegeben, so ist folgendes zu beachten:The invention is based on a prior art according to DE 29 24 128 A1. This document discloses an injection device for a pre-injection of ignitable fuel and a main injection of ignition-inert fuel, via a two-needle injection valve, in which both valve needles are arranged coaxially one inside the other, which also means a correspondingly adapted supply of the different fuels via suitably designed conduction paths in view means the timing of the pre and main injection. However, this solution poses problems or has certain disadvantages, which are discussed in more detail below. The injection pump must always be operated with the slow ignition fuel. This can lead to problems because, for example, ethanol has a low lubricity or, if a water-based emulsion is used as fuel, this can cause corrosion. In addition, in this known solution, starting from the injection pump, either constant pressure valves (FIG. 2), throttle check valves (FIG. 3) or constant space valves (FIG. 4) are provided, due to which certain problems occur in the metering of the fuel delivered. If the metering is to be controlled only by pressure and cross-section, as stated in the description on page 7 below, the following must be observed:

Der Standdruck in der Einspritzleitung muß sehr niedrig und konstant sein, vorzugsweise gleich dem Dampfdruck. Diese Forderung kann vom Gleichdruckventil nach Fig. 2 in der Praxis nicht erfüllt werden. Von den Druckventilen nach Fig. 3 und 4 kann diese Forderung nur durch eine Überentlastung der Einspritzleitung erfüllt werden, so daß im allgemeinen auch nach Zuführung des Haupteinspritzkraftstoffes die Einspritzleitung nicht vollständig gefüllt ist. Dieser Sachverhalt bedingt eine Reihe bekannter Nachteile, wie Kavitation, Streuung von Einspritzmenge und -beginn, geringer Einspritzdruck.The stand pressure in the injection line must be very low and constant, preferably equal to the vapor pressure. In practice, this requirement cannot be met by the constant pressure valve according to FIG. 2. 3 and 4, this requirement can only be met by overloading the injection line, so that the injection line is generally not completely filled even after the main injection fuel has been supplied. This fact causes a number of known disadvantages, such as cavitation, spread of injection quantity and start, low injection pressure.

Die exakte Zumessung versagt bei druck-/querschnittsgesteuerten Systemen spätestens dann, wenn die eingespritzte Kraftstoffmenge kleiner ist als die Sollmenge für den Voreinspritzkraftstoff. Dieser Fall tritt bei sehr niedriger Last ein und führt dazu, daß sich die Leitung immer mehr mit Voreinspritzkraftstoff füllt. Akute Probleme verursacht dies insbesondere dann, wenn die beiden Kraftstoffe unterschiedliche Heizwerte besitzen, was sowohl für die Kombination Dieselkraftstoff/Diesel-Wasser-Emulsion als auch für die Kombination Dieseikraftstoff/Äthanol der Fall ist. Dadurch wird nämlich bei zu großer Vorlagerung von Voreinspritzkraftstoff eine zu große Brennstoffenergie in den Motor eingebracht, was zu unkontrollierter Leistungsabgabe, Schwarzrauch und eventuell auch zu Motorzerstörung führen kann. Solche Nachteile können aber auch bei einer Magnetventildosierung auftreten, falls es das betreffende Druckventil erlaubt, mehr Menge an Voreinspritzkraftstoff zuzuführen als zuletzt eingespritzt wurde.In pressure / cross-section controlled systems, the exact metering fails at the latest when the injected fuel quantity is less than the target quantity for the pre-injection fuel. This occurs at a very low load and causes the line to fill up with pilot fuel more and more. This causes acute problems, in particular, when the two fuels have different calorific values, which is the case both for the combination of diesel fuel / diesel water emulsion and for the combination of this fuel / ethanol. As a result, if the pre-injection fuel is stored too large, too much fuel energy is introduced into the engine, which can lead to uncontrolled power output, black smoke and possibly even engine destruction. Such disadvantages can also occur with a solenoid valve metering, if the pressure valve in question allows more quantity of pre-injection fuel to be supplied than was injected last.

Es ist daher Aufgabe der Erfindung, eine Kraftstoffeinspritzvorrichtung der eingangs genannten Art dahingehend auszubilden, daß in allen Lastbereichen der Brennkraftmaschine eine exakte mengenmäßige Dosierung des Vor- und Haupteinspritzkraftstoffes sowie eine zeitlich exakt aufeinander abgestimmte Vor- und Haupteinspritzung möglich ist.It is therefore an object of the invention to design a fuel injection device of the type mentioned at the outset in such a way that an exact quantitative metering of the pre-injection and main injection fuel as well as pre-injection and main injection precisely coordinated in time are possible in all load ranges of the internal combustion engine.

Diese Aufgabe ist erfindungsgemäß dadurch gelöst,

  • daß jedes Zwei-Nadel-Einspritzventil zwei achsparallel nebeneinander eingebaute Düsennadeln aufweist, die jeweils rückseitig über eine den Öffnungsdruck vorgebende Druckfeder in Schließrichtung kraftbeaufschlagt sind und in Schließstellung, auf einem Sitz abgestützt, zugehörige Düsenbohrungen absperren bzw. in Öffnungsstellung letztere für Einspritzung freigeben,
  • daß der Düsenvorraum der Voreinspritznadel über einen ventilinternen Kanal mit eingebautem, nur in Speiserichtung durchlässigem Rückschlagventil von einer Niederdruck-Speiseeinrichtung her mit Voreinspritzkraftstoff versorgbar ist,
  • daß sich an jeden Pumpenraum der Einspritzpumpe ein ein Druckventil und eine Druckfeder aufnehmender Pumpenausgangsraum und daran über eine Einspritzleitung oder direkt ein einspritzventilinterner Zuführkanal anschließt,
  • daß jedes Druckventil beim Pumpenkolben-Hub als Druckkolben wirkend den in den anschließenden Leitungswegen gegebenen Kraftstoff ausschiebt und gleichzeitig eine seitlich in den Pumpenausgangsraum einmündende Füllbohrung absperrt, über die nach Beendigung jedes Haupteinspritzvorganges und Rückführung des Druckventils in Schließstellung der dadurch entstehende, der eingespritzten Kraftstoffmenge entsprechende Hohlraum in den nachgeordneten Leitungswegen von einer Niederdruck-Speiseeinrichtung her wieder mit Haupteinspritzkraftstoff auffüllbar ist, und
  • daß in jedem Zwei-Nadel-Einspritzventil ein zwischen zwei Endstellungen axial frei beweglicher Steuerkolben vorgesehen ist, der aus seiner einen, unteren Endstellung nach Beendigung jeder Haupteinspritzung durch seinem Steuervorraum über einen Kanal vom Düsenvorraum der Voreinspritznadel her zugeführten Voreinspritzkraftstoff in seine andere, obere Endstellung verschiebbar ist, wobei der Zuführkanal verschlossen wird, und der aus dieser oberen Endstellung bei pumpenkolbenseitig gesteuertem Druckaufbau durch den anstehenden Haupteinspritzkraftstoff nach unten bewegt wird, wobei der in seinen Steuervorraum anstehende Voreinspritzkraftstoff unter Öffnung der Voreinspritznadel verdrängt und in entsprechender Menge eingespritzt wird, und wobei vom Steuerkolben eine Verbindung zum Düsenvorraum der Haupteinspritznadel freigegeben wird, wodurch diese dann durch den pumpenkolbenseitig nachgeschobenen Haupteinspritzkraftstoff angehoben wird und letzterer bis zur pumpenkolbenseitigen Druckentlastung eingespritzt wird.
According to the invention, this object is achieved by
  • that each two-needle injection valve has two nozzle needles installed parallel to each other, each of which is pressurized in the closing direction by a compression spring that specifies the opening pressure, and in the closed position, supported on a seat, shut off associated nozzle bores or release the latter for injection in the open position,
  • that the nozzle antechamber of the pre-injection needle via a valve-internal channel with a built-in check valve that is only permeable in the feed direction can be supplied with pre-injection fuel from a low-pressure feed device,
  • that a pump outlet space accommodating a pressure valve and a compression spring is connected to each pump chamber of the injection pump and is connected to it via an injection line or directly via an injection channel internal to the injection valve,
  • that each pressure valve, acting as a pressure piston during the pump piston stroke, pushes out the fuel given in the subsequent line paths and at the same time shuts off a filling hole that opens laterally into the pump outlet space, via which, after completion of each main injection process and return of the pressure valve to the closed position, the resulting cavity corresponding to the injected fuel quantity can be refilled with main injection fuel in the downstream line routes from a low-pressure feed device, and
  • that in each two-needle injector between two end positions axially freely movable control piston is provided, which can be displaced from its one lower end position after the end of each main injection through its control antechamber via a channel from the nozzle antechamber of the pre-injection needle to its other, upper end position is, the supply channel is closed, and which is moved down from this upper end position when the pressure build-up is controlled by the main injection fuel, the pre-injection fuel coming into its control antechamber being displaced while opening the pre-injection needle and being injected in an appropriate amount, and whereby from the control piston a connection to the nozzle antechamber of the main injection needle is released, whereby this is then raised by the main injection fuel pushed in on the pump piston side and the latter up to the pressure on the pump piston side relief is injected.

Durch die erfindungsgemäße Aufteilung des Zwei-Nadel-Einspritzventils in zwei achsparallel nebeneinander eingebaute Düsennadeln kann jede derselben vergleichsweise einfach ausgebildet und auch der Öffnungsdruck über die jeweils zugeordnete Druckfeder exakt definiert eingestellt werden. Ferner erlaubt dies eine günstige Ausgestaltung der Leitungswege für die Zuführung des Voreinspritzkraftstoffes zum Düsenvorraum der Voreinspritznadel sowie einen einfachen Einbau des notwendigen Rückschlagventiles. Darüber hinaus ermöglicht die erfindungsgemäße Anordnung der Düsennadeln auch eine einfache Unterbringung des erfindungsgemäßen Steuerkolbens als einem Teil der Einspritzsteuerung. Außerdem dient die Einspritzpumpe bei der erfindungsgemäßen Lösung nicht zur Kraftstofförderung, sondern nur zum Druckaufbau, um den in den sich an das Druckventil anschließenden Leitungswegen gegebenen, von einer Niederdruck-Speiseeinrichtung her eingespeisten Haupteinspritzkraftstoff auszuschieben. Diesem Zweck dient jenes erfindungsgemäße Merkmal, daß sich an jeden Pumpenraum der Einspritzpumpe ein ein Druckventil und eine Druckfeder aufnehmender Pumpenausgangsraum und daran eine mit einem einspritzventilinternen Zuführkanal verbundene Einspritzleitung anschließt. Jedes Druckventil wirkt dabei bei jedem Pumpenkolbenhub als Druckkolben, schiebt dabei den in den anschließenden Leitungswegen gegebenen Kraftstoff aus und sperrt gleichzeitig eine seitlich in den Pumpenausgangsraum einmündende Füllbohrung ab, über die nach Beendigung jedes Haupteinspritzvorganges und Rückführung des Druckventils in dessen Schließstellung der dadurch entstehende Hohlraum in den nachgeordneten Leitungswegen von einer Niederdruckspeiseeinrichtung her wieder mit Haupteinspritzkraftstoff auffüllbar ist.The inventive division of the two-needle injection valve into two nozzle needles installed next to one another parallel to the axis allows each of them to be used Comparatively simple and the opening pressure can be set exactly defined via the respectively assigned compression spring. Furthermore, this allows a favorable design of the line paths for the supply of the pre-injection fuel to the nozzle antechamber of the pre-injection needle and a simple installation of the necessary check valve. In addition, the arrangement of the nozzle needles according to the invention also makes it easy to accommodate the control piston according to the invention as part of the injection control. In addition, the injection pump in the solution according to the invention is not used to deliver fuel, but only to build up pressure in order to push out the main injection fuel that is fed into the line paths that follow the pressure valve and is fed in from a low-pressure feed device. This is the purpose of the feature according to the invention that each pump chamber of the injection pump is followed by a pump outlet chamber receiving a pressure valve and a compression spring and an injection line connected to a supply channel inside the injection valve. Each pressure valve acts as a pressure piston with each pump piston stroke, pushing out the fuel given in the subsequent conduit paths and at the same time shutting off a filling hole that opens laterally into the pump outlet space, via which, after each main injection process and return of the pressure valve to its closed position, the resulting cavity in the downstream lines can be refilled with main injection fuel from a low-pressure feed device.

Die solchermaßen wirkende Einspritzpumpe, die Druckventile und die Steuerkolben in den Zwei-Nadel-Einspritzventilen ermöglichen in Verbindung mit dem weiteren Aufbau der letzteren eine exakte Erfüllung der gestellten Aufgaben, nämlich eine exakte mengenmäßige Dosierung sowohl des Vor- als auch Haupteinspritzkraftstoffes und eine zeitlich exakt definierte Abfolge der Vor- und Haupteinspritzung.The injection pump acting in this way, the pressure valves and the control pistons in the two-needle injection valves, in conjunction with the further construction of the latter, enable exact fulfillment of the tasks set, namely an exact quantitative dosage of both the pre- and main injection fuel and a precisely defined time Sequence of the pre and main injection.

Vorteilhafte Ausgestaltungen und Weiterbildungen der erfindungsgemäßen Lösung sind in den Unteransprüchen angegeben.Advantageous refinements and developments of the solution according to the invention are specified in the subclaims.

Was das Vorsehen zweier achsparallel nebeneinander eingebauter Düsennadeln in einem Zwei-Nadel-Einspritzventil sowie eines zwischen zwei Endstellungen beweglichen Steuerkolbens anbelangt, so ist solches aus der EP-A 0 237 071 bekannt. Im Gegensatz zur Erfindung sind dort beide Ventilnadeln über eine Wippe an einer gemeinsamen Druckfeder abgestützt. Ersichtlicherweise kann diese nur auf einen einzigen Öffnung- bzw. Schließdruck eingestellt sein. Eine gezielte Einstellung des Öffnungs- bzw. Schließdruckes jeder Ventilnadel, wie bei der Erfindung über die beiden Druckfedern möglich, ist dort nicht darstellbar. Im übrigen ist das Steuerungssystem für die Steuerung der Vor- und Haupteinspritzung extrem aufwendig. Drei Nockenwellen allein für die Steuerung der Einspritzungen sind in der Praxis kaum vertretbar. Die Erfindung begnügt sich, was Nockenwellen anbelangt, mit einer einzigen, nämlich jener, die zur Steuerung der Pumpenkolben der Einspritzpumpe dient.As for the provision of two nozzle needles installed axially parallel next to one another in a two-needle injection valve and a control piston movable between two end positions, such is known from EP-A 0 237 071. In contrast to the invention, both valve needles are supported there on a rocker on a common compression spring. Obviously, this can only be set to a single opening or closing pressure. A targeted setting of the opening or closing pressure of each valve needle, as is possible with the two pressure springs in the invention, cannot be represented there. In addition, the control system for controlling the pre-injection and main injection is extremely complex. In practice, three camshafts alone for controlling the injections are hardly justifiable. As far as camshafts are concerned, the invention is satisfied with a single one, namely that which is used to control the pump pistons of the injection pump.

Nachstehend ist die erfindungsgemäße Lösung anhand der Zeichnung näher erläutert. In der Zeichnung zeigen:

Fig. 1
eine Ausführungsform der erfindungsgemäßen Kraftstoffeinspritzvorrichtung für eine Vor- und Haupteinspritzung gleichen Kraftstoffs,
Fig. 2
eine Ausführungsform der erfindungsgemäßen Kraftstoffeinspritzvorrichtung für eine Voreinspritzung zündwilligen Kraftstoffs und eine Haupteinspritzung zündträgen Kraftstoffs,
Fig. 3
einen Ausschnitt aus einem zu jenem in Fig. 1 und 2 dargestellen alternativen Zwei-Nadel-Einspritzventil,
Fig. 4
ausschnittsweise ein weiteres alternatives Zwei-Nadel-Einspritzventil, wobei in den Fig. 4A, 4B und 4C der dort eingebaute Steuerkolben in drei unterschiedlichen Stellungen gezeigt ist, nämlich in Fig. 4A vor einer Voreinspritzung, in Fig. 4B am Ende einer Voreinspritzung und in Fig. 4C während einer Haupteinspritzung,
Fig. 5
ausschnittsweise eine weitere zur Ausführungsform gemäß Fig. 1 und 2 alternative Ausgestaltung des Zwei-Nadel-Einspritzventils.
The solution according to the invention is explained in more detail below with reference to the drawing. The drawing shows:
Fig. 1
An embodiment of the fuel injection device according to the invention for a pre and main injection of the same fuel,
Fig. 2
1 an embodiment of the fuel injection device according to the invention for a pre-injection of ignitable fuel and a main injection of ignitable fuel,
Fig. 3
1 shows a section of an alternative two-needle injector to that shown in FIGS. 1 and 2,
Fig. 4
Detail of a further alternative two-needle injection valve, the control piston installed there being shown in FIGS. 4A, 4B and 4C in three different positions, namely in FIG. 4A before a pre-injection, in FIG. 4B at the end of a pre-injection and in 4C during a main injection,
Fig. 5
Detail of a further embodiment of the two-needle injection valve that is alternative to the embodiment according to FIGS. 1 and 2.

In den Figuren sind gleiche bzw. einander entsprechende Bauteile mit gleichem Bezugszeichen angezogen.In the figures, the same or corresponding components are drawn with the same reference numerals.

Die Kraftstoffeinspritzvorrichtung weist eine Einspritzpumpe 1 mit von nicht dargestellten Nocken gesteuerten Pumpenkolben 2 auf, die jeweils übliche Steuernuten 3, 4 und schräge Steuerkanten 5 aufweisen sowie für Leistungsregelung durch eine ebenfalls nicht dargestellte Steuervorrichtung verdrehbar sind. An die jeweils über eine seitlich einmündende Steuerbohrung 6 mit Kraftstoff füllbaren Pumpenräume 7 schließt sich ausgangs jeweils ein Pumpenausgangsraum 8 und daran eine mit einem intern eines Zwei-Nadel-Einspritzventiles 9 gegebenen Zuführkanal 10 verbundene Einspritzleitung 11 an. Falls das Zwei-Nadel-Einspritzventil 9 mit der Einspritzpumpe 1 zu einem Pumpen-Düsen-Organ vereinigt ist, entfällt die Einspritzleitung 11. Die zwischen jedem Pumpenraum 7 und Pumpenausgangsraum 8 gegebene Verbindungsbohrung 12 ist rückseitig mit einer kegligen Erweiterung 13 versehen, die als Sitz für ein im Pumpenausgangsraum 8 leckagearm eingebautes Druckventil 14 dient, welches in Schließrichtung durch eine ebenfalls in den Pumpenausgangsraum 8 eingebaute Druckfeder 15 beaufschlagt ist. Im Gegensatz zu herkömmlichen Einspritzpumpen, bei denen durch den Pumpenkolben-Hub der geförderte Kraftstoff unmittelbar einem Einspritzventil zugeführt wird, dient die erfindungsgemäße Einspritzpumpe nur zum Druckaufbau und zum Ausschub der zur Einspritzung kommenden Menge an Haupteinspritzkraftstoff, welcher sukzessive den sich am Druckventil 14 anschließenden Leitungswegen 8, 11, 10 zugeführt wird. Dabei wirkt jedes Druckventil 14 beim Pumpenkolben-Hub als Druckkolben, der durch seine Hubbewegung den dahinter anstehenden Kraftstoff ausschiebt und gleichzeitig eine seitlich in den Pumpenausgangsraum 8 einmündende Füllbohrung 16 absperrt, über die nach Beendigung jedes Haupteinspritzvorganges und Rückführung des Druckventils 14 in dessen Schließstellung der dadurch entstehende Hohlraum in den besagten, letzterem nachgeordneten Leitungswegen 8, 11, 10 von einer Niederdruck-Speiseeinrichtung 17 her wieder mit Haupteinspritzkraftstoff auffüllbar sind.The fuel injection device has an injection pump 1 with pump pistons 2 controlled by cams (not shown), each of which has conventional control grooves 3, 4 and oblique control edges 5 and can be rotated by a control device (also not shown) for power control. A pump outlet chamber 8 is connected to each of the pump chambers 7, which can be filled with fuel via a laterally opening control bore 6, and an injection line 11, which is connected to an internally of a two-needle injection valve 9, is connected to this. If the two-needle injection valve 9 is combined with the injection pump 1 to form a pump nozzle member, the injection line 11 is omitted. The connection bore 12 between each pump chamber 7 and pump outlet chamber 8 is provided on the rear with a conical extension 13, which serves as a seat serves for a pressure valve 14 installed in the pump outlet chamber 8 with little leakage, which is acted upon in the closing direction by a compression spring 15 likewise installed in the pump outlet chamber 8. In contrast to conventional injection pumps, where Due to the pump piston stroke, the fuel delivered is fed directly to an injection valve, the injection pump according to the invention only serves to build up pressure and to push out the amount of main injection fuel that is to be injected, which fuel is successively fed to the line paths 8, 11, 10 connected to the pressure valve 14. Each pressure valve 14 acts as a pressure piston during the pump piston stroke, which pushes out the fuel behind it due to its stroke movement and at the same time blocks a filling bore 16 that opens laterally into the pump outlet space 8, via which, after the completion of each main injection process and return of the pressure valve 14 into its closed position, thereby resulting cavity in said, downstream of the latter lines 8, 11, 10 from a low-pressure feed device 17 can be refilled with main injection fuel.

Jedes einem Zylinder der Brennkraftmaschine zugeordnete Zwei-Nadel-Einspritzventil 9 weist zwei achsparallel nebeneinander eingebaute Düsennadeln, eine Voreinspritznadel 18 und eine Haupteinspritznadel 19 auf, die jeweils rückseitig über eine an einem Druckteller abgestützte und den Öffnungsdruck vorgebende Druckfeder 20 bzw. 21 in Schließrichtung kraftbeaufschlagt sind und in Schließstellung, auf einem Sitz 22 bzw. 23 abgestützt, zugehörige Düsenbohrungen 24 bzw. 25 absperren bzw. in Öffnungsstellung letztere für Einspritzung freigeben. Um zu erreichen, daß zunächst eine Voreinspritzung von Voreinspritzkraftstoff durch die Düsenbohrungen 24 nach Abheben der Voreinspritznadel 18 von ihrem Sitz 22 und danach eine Haupteinspritzung über die Düsenbohrungen 25 nach Abheben der Haupteinspritznadel 19 von ihrem Sitz 23 erfolgen kann, ist der Öffnungsdruck der Voreinspritznadel 18 vorzugsweise niedriger, z.B. auf ≦ 70% als jener der Haupteinspritznadel 19 eingestellt, und zwar über entsprechende Auslegung der Druckfedern 20, 21. Beispielsweise kann der Öffnungsdruck der Voreinspritznadel 18 auf 200 bar und der Öffnungsdruck der Haupteinspritznadel auf 300 bar eingestellt sein. Abhängig von dieser Öffnungsdruck-Einstellung ergibt sich ein bestimmter zeitlicher Versatz des Beginns von Vor- und Haupteinspritzung.Each two-needle injection valve 9 assigned to a cylinder of the internal combustion engine has two nozzle needles installed axially parallel to one another, a pre-injection needle 18 and a main injection needle 19, each of which is acted upon in the closing direction by a compression spring 20 or 21 supported on a pressure plate and defining the opening pressure and in the closed position, supported on a seat 22 or 23, shut off the associated nozzle bores 24 or 25 or in the open position release the latter for injection. In order to achieve that a pre-injection of pre-injection fuel through the nozzle bores 24 after lifting the pre-injection needle 18 from its seat 22 and then a main injection via the nozzle bores 25 after lifting the main injection needle 19 from its seat 23 can take place, the opening pressure of the pre-injection needle 18 is preferred lower, e.g. set to ≦ 70% than that of the main injection needle 19, specifically by designing the compression springs 20, 21. For example, the opening pressure of the pre-injection needle 18 can be set to 200 bar and the opening pressure of the main injection needle to 300 bar. Depending on this opening pressure setting, there is a certain time offset between the start of the pre-injection and the main injection.

Jede der beiden Düsennadeln 18, 19 weist einen vorderen zylindrischen Abschnitt und einen demgegenüber durchmessergrößeren hinteren Abschnitt auf, wobei die Übergangsfläche 26 bzw. 27 zwischen beiden Nadelabschnitten im erweiterten Bereich des jeweils zugehörigen Düsenvorraumes 28 bzw. 29 gegeben ist und die in Öffnungsrichtung der jeweiligen Ventilnadel 18 bzw. 19 wirksame Druckfläche bildet.Each of the two nozzle needles 18, 19 has a front cylindrical section and a rear section which is larger in diameter, the transition surface 26 or 27 between the two needle sections being provided in the enlarged area of the associated nozzle antechamber 28 and 29, respectively forms the effective pressure area in the opening direction of the respective valve needle 18 or 19.

Der Düsenvorraum 28 der Voreinspritznadel 18 ist über einen ventilinternen Kanal 30/1, 30/2, 30/3, 30/4 mit vorzugsweise möglichst nahe vor dessen Einmündung in den Düsenvorraum 28 eingebautem, nur in Speiserichtung durchlässigen Rückschlagventil 31 von einer Niederdruck-Speiseeinrichtung 32 her mit Voreinspritzkraftstoff versorgbar.The nozzle antechamber 28 of the pre-injection needle 18 is from a low-pressure feed device via a valve-internal channel 30/1, 30/2, 30/3, 30/4 with a check valve 31 which is preferably installed as close as possible before its junction in the nozzle antechamber 28 and is only permeable in the feed direction 32 ago with pre-injection fuel.

Kernstück der Kraftstoffeinspritzvorrichtung ist ein in jedem Zwei-Nadel-Einspritzventil 9 eingebauter, zwischen zwei Endstellungen axial frei beweglicher Steuerkolben 33, der für eine exakte mengenmäßige Dosierung der Voreinspritzkraftstoffmenge und eine zeitlich exakt definierte Steuerung der Voreinspritzung sowie eine zeitlich versetzt zu deren Beginn mit oder ohne Überschneidung gesteuerte Haupteinspritzung verantwortlich zeichnet. Dieser Steuerkolben 33 ist im Bereich zwischen den beiden Ventilnadeln 18, 19 vorzugsweise achsparallel zu diesen in einer Aufnahmebohrung 34 axial verschieblich aufgenommen, die unten - zur Bildung eines Steuervorraumes 35 - und weiter oben, von dem den unteren Anschlag bildenden Boden des letzteren um etwa die Länge des Steuerkolbens 33 beabstandet - zur Bildung eines Überleitraumes 36 - entsprechend erweitert ist sowie koaxial zum zentralen, durchmesserkleineren Zuführkanal 10 verläuft, wobei der Übergang von letzterem zur Aufnahmebohrung 34 durch eine Einsatzhülse 37 gebildet ist, deren untere Stirnfläche den oberen Anschlag für den Steuerkolben 33 bildet.The centerpiece of the fuel injection device is a control piston 33, which is installed in each two-needle injection valve 9 and is axially freely movable between two end positions, for an exact quantitative metering of the pre-injection fuel quantity and a precisely defined control of the pre-injection as well as a time offset at the beginning with or without Overlap controlled main injection is responsible. This control piston 33 is in the region between the two valve needles 18, 19 preferably axially displaceably axially displaceably received in a receiving bore 34 which below - to form a control antechamber 35 - and further up, from which the bottom stop forming the bottom of the latter by about The length of the control piston 33 spaced apart - to form a transfer space 36 - is correspondingly expanded and extends coaxially to the central, smaller-diameter feed channel 10, the transition from the latter to the receiving bore 34 being formed by an insert sleeve 37, the lower end face of which is the upper stop for the control piston 33 forms.

Der Steuervorraum 35 des Steuerkolbens 33 ist über eine Bohrung 38 mit dem Düsenvorraum 28 der Voreinspritznadel verbunden. Der Überleitraum 36 wiederum ist mit dem Düsenvorraum 29 der Haupteinspritznadel verbunden, und zwar je nach Abstand unter Anschneidung derselben oder über eine Bohrung.The control antechamber 35 of the control piston 33 is connected via a bore 38 to the nozzle antechamber 28 of the pre-injection needle. The transfer chamber 36 is in turn connected to the nozzle antechamber 29 of the main injection needle, depending on the distance by cutting the same or via a bore.

Der Steuerkolben 33 ist nach Beendigung jeder Haupteinspritzung generell aus seiner einen, nach Beendigung einer Voreinspritzung gegebenen unteren Endstellung durch von der Niederdruck-Speiseeinrichtung 32 nachgeförderten und seinem Steuervorraum 35 über den Kanal 38 vom Düsenvorraum 28 der Voreinspritznadel 18 her zugeführten Voreinspritzkraftstoff in seine andere, obere Endstellung verschiebbar, wobei während dieser Aufwärtsbewegung der Zuführkanal 10 verschlossen wird. Aus dieser oberen Endstellung ist der Steuerkolben 33 bei einem pumpenkolbenseitig gesteuerten Druckaufbau über den davor im Zuführkanal 10 anstehenden Haupteinspritzkraftstoff nach unten bewegbar, wobei der in seinem Steuervorraum 35 anstehende Voreinspritzkraftstoff - wegen des geschlossenen Rückschlagventils 31 - unter Öffnung der Voreinspritznadel 18 verdrängt und in den Brennraum eingespritzt wird, und wobei nach einem gewissen Weg vom Steuerkolben 33 die Verbindung zwischen Zuführkanal 10 und Überleitraum 36 und damit der Kraftstoffweg zum Düsenvorraum 29 der Haupteinspritznadel 19 freigegeben ist, worauf letztere dann durch den Druckausstieg des pumpenkolbenseitig nachgeschobenen Haupteinspritzkraftstoffs angehoben und letzterer bis zur pumpenkolbenseitigen Druckentlastung eingespritzt wird.After each main injection has ended, the control piston 33 is generally from its one, after the end of a pre-injection, given the lower end position by the low-pressure feed device 32 and its control antechamber 35 via the channel 38 from the nozzle antechamber 28 of the pre-injection needle 18 into its other, upper injection fuel End position displaceable, the feed channel during this upward movement 10 is closed. From this upper end position, the control piston 33 can be moved downward in the case of a pressure build-up controlled on the pump piston side via the main injection fuel present in the feed channel 10, the pre-injection fuel present in its control antechamber 35 being displaced - due to the closed check valve 31 - by opening the pre-injection needle 18 and into the combustion chamber is injected, and after a certain distance from the control piston 33 the connection between the feed channel 10 and the transfer chamber 36 and thus the fuel path to the nozzle antechamber 29 of the main injection needle 19 is released, whereupon the latter is then raised by the pressure rise of the main injection fuel supplied on the pump piston side and the latter up to the pressure on the pump piston side is injected.

Der Steuerkolben 33 ist bei den Ausführungsbeispielen gemäß Fig. 1 und 2 zylindrisch mit ebenen, randseitig erforderlichenfalls angefasten Stirnflächen ausgebildet. Hierdurch ergibt sich folgender Einspritzzyklus, betrachtet von folgenden Ausgangsgegebenheiten:

  • der Steuerkolben 33 befindet sich durch die Nachfüllung des Voreinspritzkraftstoffes nach oben bewegt in seiner oberen Endstellung,
  • der Pumpenausgangsraum 8, die Einspritzleitung 11 und der Zuführkanal 10 sind vollständig mit Haupteinspritzkraftstoff gefüllt,
  • der Pumpenkolben 2 befindet sich in unterster Stellung.
In the exemplary embodiments according to FIGS. 1 and 2, the control piston 33 is cylindrical with flat end faces chamfered on the edge if necessary. This results in the following injection cycle, viewed from the following initial conditions:
  • the control piston 33 is moved upwards in its upper end position due to the refilling of the pre-injection fuel,
  • the pump outlet space 8, the injection line 11 and the feed channel 10 are completely filled with main injection fuel,
  • the pump piston 2 is in the lowest position.

Wenn sich nun der Pumpenkolben 2 von einer nicht dargestellten Nocke angetrieben nach oben bewegt, verschließt er die Steuerbohrung 6, wodurch der Druck im Pumpenraum 7 ansteigt und das Druckventil 14 entgegen der Kraft der Druckfeder 15 angehoben wird. Das Druckventil 14 verschließt nach kurzem Hub die Füllbohrung 16, worauf die in den nachfolgenden Leitungswegen 8, 11, 10 anstehende Haupteinspritzkraftstoffsäule durch die Weiterbewegung des als Druckkolben wirkenden Druckventiles 14 vorangeschoben wird. Sobald der Druck dieser Haupteinspritzkraftstoffsäule den über die Druckfeder 20 eingestellten Öffnungsdruck der Voreinspritznadel 18 übersteigt, wird der einspritzventilinterne Steuerkolben 33 aus seiner oberen Endstellung nach unten verschoben, wobei durch den hierdurch aus seinem Steuervorraum 35 verdrängten Voreinspritzkraftstoff die Voreinspritznadel 18 angehoben und dann bei weiterer haupteinspritzkraftstoffgesteuerter Abwärtsbewegung des Steuerkolbens 33 bis zu dessen unterer Endstellung die dieser Volumenverdrängung entsprechende Menge an Voreinspritzkraftstoff über die Düsenbohrungen 24 in den Brennraum der Brennkraftmaschine eingespritzt wird. Da der pumpenkolbengesteuerte Druck relativ rasch ansteigt, ist bei der Ausführungsform des Steuerkolbens gemäß Fig. 1 und 2 nur ein kleiner Versatz zwischen Vor- und Haupteinspritzung erreichbar. Es erfolgt mithin eine Überdeckung zwischen Vor- und Haupteinspritzung deswegen, weil vom Steuerkolben 33 bereits nach einem gewissen Abwärtshub die Verbindung vom Zuführkanal 10 zum Düsenvorraum 29 der Haupteinspritznadel 19 freigegeben wird und letztere, sobald deren durch die Druckfeder 21 eingestellte Öffnungsdruck überschritten wird, angehoben wird und dann exakt jene Menge an Haupteinspritzkraftstoff über die Düsenbohrungen 25 in den Brennraum der Brennkraftmaschine eingespritzt wird, welche sich aus dem restlichen Hubweg des Druckventiles 14 ergibt. Die Voreinspritzung wird im Fall gemäß Fig. 1 und 2 beendet, sobald der einspritzventilinterne Steuerkolben 33 seine unterste Anschlagposition erreicht hat, die Haupteinspritzung dauert so lange, bis der Druck im Pumpenraum 7 bei Förderende des Pumpenkolbens 2 und damit einhergehend auch der Druck in den Leitungswegen 8, 11, 10 zusammenbricht. In der Folge schließt die Haupteinspritznadel 19 und das Druckventil 14 wird in seine Schließstellung rückgeführt. Dadurch entsteht in den diesem nachfolgenden Leitungswegen 8, 11, 10 ein Hohlraum in der Größe der eingespritzten Kraftstoffmenge. Dieser Hohlraum wird von der Niederdruck-Speiseeinrichtung 17 her über die Füllbohrung 16 wieder aufgefüllt. Andererseits wird bereits bei Zusammenbruch des Druckes in den Leitungswegen 8, 11, 10 der zur Voreinspritzung vorgesehene Kraftstoff von der Niederdruck-Speiseeinrichtung 32 her nachgefüllt, und zwar über die ventilinternen Leitungswege 30/1, 30/2, 30/3, 30/4 unter Öffnung des Rückschlagventils 31 und Auffüllung des Düsenvorraumes 28 der Voreinspritznadel 18, der Bohrung 38 und des Steuervorraumes 35 des Steuerkolbens 33, wodurch dieser von seiner unteren Anschlagposition in seine obere Anschlagposition unter Absperrung des Zuführkanales 10 bewegt wird.If the pump piston 2 now moves upwards driven by a cam (not shown), it closes the control bore 6, as a result of which the pressure in the pump chamber 7 increases and the pressure valve 14 is raised against the force of the compression spring 15. After a short stroke, the pressure valve 14 closes the filling bore 16, whereupon the main injection fuel column in the subsequent line paths 8, 11, 10 is advanced by the further movement of the pressure valve 14, which acts as a pressure piston. As soon as the pressure of this main injection fuel column exceeds the opening pressure of the pre-injection needle 18 set via the compression spring 20, the injector-internal control piston 33 is shifted downward from its upper end position, whereby the pre-injection fuel 18 thus displaced from its control antechamber 35 raises the pre-injection needle 18 and then with further main-controlled injection fuel Downward movement of the control piston 33 up to its lower end position the amount of pre-injection fuel corresponding to this volume displacement is injected into the combustion chamber of the internal combustion engine via the nozzle bores 24. Since the pump piston-controlled pressure rises relatively quickly, only a small offset between the pre-injection and the main injection can be achieved in the embodiment of the control piston according to FIGS. 1 and 2. There is therefore an overlap between the pre-injection and the main injection because the connection from the supply duct 10 to the nozzle vestibule 29 of the main injection needle 19 is released by the control piston 33 after a certain downward stroke and the latter is raised as soon as the opening pressure set by the compression spring 21 is exceeded and then exactly that amount of main injection fuel is injected via the nozzle bores 25 into the combustion chamber of the internal combustion engine, which results from the remaining stroke of the pressure valve 14. 1 and 2, as soon as the injector-internal control piston 33 has reached its lowermost stop position, the main injection continues until the pressure in the pump chamber 7 at the end of the delivery of the pump piston 2 and, with it, the pressure in the line paths 8, 11, 10 collapses. As a result, the main injection needle 19 closes and the pressure valve 14 is returned to its closed position. This creates a cavity in the line paths 8, 11, 10 following this, the size of the injected fuel quantity. This cavity is filled up again by the low-pressure feed device 17 via the filling bore 16. On the other hand, when the pressure in the line paths 8, 11, 10 collapses, the fuel provided for the pre-injection is refilled by the low-pressure feed device 32, specifically via the valve-internal line paths 30/1, 30/2, 30/3, 30/4 by opening the check valve 31 and filling the nozzle antechamber 28 of the pre-injection needle 18, the bore 38 and the control antechamber 35 of the control piston 33, as a result of which the piston 33 is moved from its lower stop position to its upper stop position with the supply channel 10 shut off.

Um zu erreichen, daß der Düsenvorraum 29 der Haupteinspritznadel 19 vor Absperrung des Zuführkanales 10 durch den Steuerkolben 33 vollständig mit Haupteinspritzkraftstoff gefüllt wird, muß im Fall der Ausführungsbeispiele gemäß Fig. 1 bis 4 die Füllung der Leitungswege 8, 11, 10 mit Haupteinspritzkraftstoff von der Niederdruck-Speiseeinrichtung 17 her wesentlich schneller erfolgen als die durch die Nachfüllung des Voreinspritzkraftstoffes erfolgende Verschiebung des Steuerkolbens 33. Dies wird dadurch erreicht, daß der Förderdruck P2 der Niederdruck-Speiseeinrichtung 17 entsprechend größer eingestellt ist als der Förderdruck P1 der Niederdruck-Speiseeinrichtung 32 und außerdem im Leitungsweg zwischen Niederdruck-Speiseeinrichtung 32 und Rückschlagventil 31 eine Drossel 39 gegeben ist, deren Durchlaßquerschnitt wesentlich kleiner ist als jener einer anderen Drossel 40, die im Leitungsweg zwischen Niederdruck-Speiseeinrichtung 17 und Pumpenausgangsraum 8 gegeben ist. Die Drossel 39 ist insbesondere eingangs eines Zwei-Nadel-Einspritzventils 9 gegeben, wahrend die Drossel 40 insbesondere eingangs des Pumpenausgangsraums 8 in der Füllbohrung 16 eingebaut ist.In order to ensure that the nozzle vestibule 29 of the main injection needle 19 is completely filled with main injection fuel before the supply duct 10 is shut off by the control piston 33, in the case of the exemplary embodiments according to FIGS. 1 to 4 the filling of the conduit paths 8, 11, 10 with main injection fuel must be carried out from the low-pressure feed device 17 take place much faster than the displacement of the control piston 33 caused by the refilling of the pre-injection fuel. This is achieved in that the delivery pressure P2 of the low-pressure feed device 17 is set correspondingly higher than the delivery pressure P1 of the low-pressure feed device 32 and also in the line path between low-pressure feed device 32 and check valve 31 there is a throttle 39, the passage cross section of which is substantially smaller than that of another throttle 40, which is given in the line path between low-pressure feed device 17 and pump outlet space 8. The throttle 39 is in particular given at the beginning of a two-needle injection valve 9, while the throttle 40 is installed in the filling bore 16 in particular at the entrance to the pump outlet space 8.

Alternativ zum Vorsehen dieser beiden Drosseln 39, 40 kann unter Verzicht derselben, um die besagte vollständige Auffüllung des Düsenvorraumes 29 der Haupteinspritznadel 19 sicherzustellen, der Steuerkolben 33 - wie aus Fig. 5 ersichtlich - eine von oben her eingebohrte Sacklochbohrung 41 und eine von dieser zum Umfang führende, erheblich durchmesserkleinere Querbohrung 42 aufweisen. Diese ist am Steuerkolben 33 in solcher axialer Relativlage vorgesehen, daß, wenn sich letzterer in oberer Endstellung befindet, eine gedrosselte Verbindung zwischen Zuführkanal 10 und Überleitraum 36 zum Düsenvorraum 29 der Haupteinspritznadel 19 besteht. Diese Querbohrung 42 wird aber bereits nach geringem Abwährtshub des Steuerkolbens 33 durch die Aufnahmebohrung 34 abgedeckt und damit verschlossen, so daß durch dessen Abwärtsbewegung die Voreinspritzung ungehindert steuerbar ist.As an alternative to the provision of these two throttles 39, 40, without the same, in order to ensure said complete filling of the nozzle vestibule 29 of the main injection needle 19, the control piston 33 - as can be seen in FIG. 5 - has a blind hole 41 drilled from above and one of the latter Have circumferential leading, considerably smaller diameter transverse bore 42. This is provided on the control piston 33 in such an axial relative position that, when the latter is in the upper end position, there is a throttled connection between the feed channel 10 and the transfer space 36 to the nozzle antechamber 29 of the main injection needle 19. However, this transverse bore 42 is covered and thus closed by the receiving bore 34 after a short downward stroke of the control piston 33, so that the pilot injection can be controlled unhindered by its downward movement.

Um einen zeitlich weitergehend versetzten Beginn von Vor- und Haupteinspritzung zu erreichen, kann der Steuerkolben 33 auch - wie aus Fig. 3 ersichtlich - als Stufenkolben ausgebildet sein. Dabei besteht der Steuerkolben 33 aus zwei durchmesserunterschiedlichen Zylinderabschnitten 33/1, 33/2, wobei der durchmesserschwächere (33/2) das untere Steuerkolbenteil bildet, an das die Aufnahmebohrung 34 durchmesserseitig entsprechend angepaßt ist. Letztere ist außerdem in Höhe des Übergangs der beiden Zylinderabschnitte 33/1, 33/2 - bei in unterer Anschlagstellung des Steuerkolbens 33 betrachtet - durch einen Leckageraum 43 erweitert, von dem ein Leckageableitkanal 44 wegführt. Aufgrund dieser stufigen Ausbildung des Steuerkolbens 33 ergibt sich eine Druckübersetzung, mit der Folge, daß bei dessen Abwärtsbewegung im Düsenvorraum 28 der Voreinspritznadel 18 ein wesentlich höherer Druck als im Düsenvorraum 29 der Haupteinspritznadel 19 bewirkt wird. Dadurch ist es möglich, den Beginn der Voreinspritzung relativ weit gegenüber dem Beginn der Haupteinspritzung vorzuverlegen. Durch entsprechende Durchmesserbemessung der beiden Zylinderabschnitte 33/1, 33/2 des Steuerkolbens 33 ist es aber auch möglich, eine Beendigung der Voreinspritzung vor Beginn der Haupteinspritzung zu erreichen.In order to achieve a start of the pre-injection and main injection which is offset in time, the control piston 33 can also - as can be seen from FIG. 3 - be designed as a stepped piston. The control piston 33 consists of two cylinder sections 33/1, 33/2 with different diameters, the smaller diameter (33/2) forming the lower control piston part, to which the receiving bore 34 is correspondingly adapted on the diameter side. The latter is also expanded at the level of the transition of the two cylinder sections 33/1, 33/2 - when viewed in the lower stop position of the control piston 33 - by a leakage space 43, from which a leakage discharge duct 44 leads away. Due to this stepped design of the control piston 33, there is a pressure ratio, with the result that when it moves downward in the nozzle vestibule 28 of the pre-injection needle 18, a significantly higher pressure than in the nozzle vestibule 29 of the main injection needle 19 is brought about. This makes it possible to advance the start of the pre-injection relatively far from the start of the main injection. By correspondingly dimensioning the diameter of the two cylinder sections 33/1, 33/2 of the control piston 33, however, it is also possible to bring the pre-injection to an end before the main injection begins.

Eine andere Lösung, mit der die Voreinspritzung vor der Haupteinspritzung beendbar ist, ist in Fig. 4A bis 4C gezeigt. Bei dieser Variante ist der Steuerkolben 33 zylindrisch mit ebener oberer Stirnfläche ausgebildet. Ferner ist das Aufnahmevolumen des Steuervorraumes 35 durch eine von unten her in den Steuerkolben 33 eingebohrte Sacklochbohrung 45 erweitert, die an einer bestimmten Stelle über eine Querbohrung 46 mit dem Umfang des Steuerkolbens 33 verbunden ist. Diese Querbohrung 46 ist bei in oberer Endstellung befindlichem Steuerkolben 33 durch die Aufnahmebohrung 34 abgedeckt und kommt bei Abwärtsbewegung des Steuerkolbens 33 mit einem durch eine ringförmige Erweiterung der Aufnahmebohrung gegebenen Leckageraum 47, von dem eine Leckageleitung 48 abgeht, in Verbindung, wodurch der Druck im Steuerdruckraum 35 und Düsenvorraum 28 zusammenbricht, damit die Voreinspritzung beendet und außerdem aufgrund der Abflußmöglichkeit des Voreinspritzkraftstoffes auch eine Rückkehr des Steuerkolbens 33 in seine untere Anschlagposition ermöglicht wird. Ansonsten ist der Ablauf eines Voreinspritz- und Haupteinspritzzyklus gleich wie in Verbindung mit Fig. 1 und 2 beschrieben. Zur Verdeutlichung ist daher nachfolgend anhand von Fig. 4A, 4B und 4C nur der Bewegungsablauf des diesbezüglichen Steuerkolbens 33 geschildert. Fig. 4A zeigt den Steuerkolben 33 in seiner oberen Anschlagsstellung, wie sie zu Beginn des pumpenkolbenseitigen Förderhubes gegeben ist. Bei einem pumpenkolbenseitig gesteuerten Druckanstieg über die in den Leitungswegen 8, 11, 10 gegebene Haupteinspritzkraftstoffsäule bewegt sich der Steuerkolben nach unten, wodurch - während die Verbindungen zwischen Zuführkanal 10 und Düsenvorraum 29 der Haupteinspritznadel 19 sowie zwischen Steuervorraum 35 und Leckageraum 47 noch verschlossen sind - der Druck im Düsenvorraum 28 ansteigt, die Voreinspritznadel 18 angehoben wird und die Voreinspritzung über die Düsenbohrungen 24 erfolgt. Nach einem gewissen Weg des Steuerkolbens 33 gibt die Aufnahmebohrung 34 die Querbohrung 46 frei - siehe die Steuerkolben-Stellung gemäß Fig. 4B. Da nunmehr Voreinspritzkraftstoff in den Leckageraum 47 abströmen kann, bricht der Druck im Düsenvorraum 28 zusammen und die Voreinspritzung wird beendet. Die zeitliche Verschiebung zwischen Ende Voreinspritzung und Beginn Haupteinspritzung ist durch die Zeit der weiteren Bewegung des Steuerkolben 33 bis zu seiner unteren Anschlagpositionsiehe Fig. 4C - definiert. Kurz bevor der Steuerkolben 33 diese untere Anschlagsposition erreicht, wird die Verbindung vom Zuführkanal 10 zum Überleitraum 36 aufgesteuert, wodurch sich ein Druckanstieg im Düsenvorraum 29 ergibt, die Haupteinspritznadel 19 geöffnet und der Haupteinspritzkraftstoff über die Düsenbohrungen 25 eingespritzt wird.Another solution with which the pre-injection can be ended before the main injection is shown in FIGS. 4A to 4C. In this variant, the control piston 33 is cylindrical with a flat upper end face. Furthermore, the receiving volume of the control antechamber 35 is expanded by a blind hole 45 drilled into the control piston 33 from below, which is connected at a certain point via a transverse bore 46 to the circumference of the control piston 33. When the control piston 33 is in the upper end position, this transverse bore 46 is covered by the receiving bore 34 and, when the control piston 33 moves downward, comes into connection with a leakage space 47 which is given by an annular expansion of the receiving bore and from which a leakage line 48 emerges, thereby causing the pressure in the control pressure chamber 35 and the nozzle antechamber 28 collapse so that the pre-injection ends and, in addition, the control piston 33 is also able to return to its lower stop position due to the possibility of the pre-injection fuel draining off. Otherwise, the course of a pre-injection and main injection cycle is the same as described in connection with FIGS. 1 and 2. 4A, 4B and 4C, only the movement sequence of the relevant control piston 33 is described below for the purpose of illustration. 4A shows the control piston 33 in its upper stop position, as is given at the beginning of the delivery stroke on the pump piston side. When the pressure on the pump piston side increases via the main injection fuel column given in the line paths 8, 11, 10, the control piston moves downwards, as a result of which - while the connections between the feed channel 10 and the nozzle chamber 29 of the main injection needle 19 and between the control chamber 35 and the leakage chamber 47 are still closed Pressure in the nozzle antechamber 28 rises, the pre-injection needle 18 is raised and the pre-injection takes place via the nozzle bores 24. After a certain path of the control piston 33, the receiving bore 34 releases the transverse bore 46 - see the spool position shown in FIG. 4B. Since pre-injection fuel can now flow into the leakage space 47, the pressure in the nozzle antechamber 28 collapses and the pre-injection is ended. The time shift between the end of the pre-injection and the start of the main injection is defined by the time of the further movement of the control piston 33 to its lower stop position, see FIG. 4C. Shortly before the control piston 33 reaches this lower stop position, the connection from the supply channel 10 to the transfer chamber 36 is opened, which results in a pressure increase in the nozzle antechamber 29, the main injection needle 19 is opened and the main injection fuel is injected via the nozzle bores 25.

Jede der beiden Niederdruck-Speiseeinrichtungen 17, 32 weist eine Förderpumpe 17/1 bzw. 32/1 und ein Druckbegrenzungsventil 17/2 bzw. 32/2 auf, über welches der Förderdruck P1 der Förderpumpe 17/1 bzw. P2 der Förderpumpe 32/1 auf einen Bereich zwischen ca. 2 bis 4 bar eingestellt ist.Each of the two low-pressure feed devices 17, 32 has a feed pump 17/1 or 32/1 and a pressure relief valve 17/2 or 32/2, via which the feed pressure P1 of the feed pump 17/1 or P2 of the feed pump 32 / 1 is set to a range between approx. 2 to 4 bar.

Die erfindungsgemäße Kraftstoffeinspritzvorrichtung kann unabhängig von ihrer jeweiligen Ausbildung grundsätzlich entweder zur Vor- und Haupteinspritzung gleichen Kraftstoffs - siehe Fig. 1 - oder zur Voreinspritzung eines zündwilligen Kraftstoffs, insbesondere Dieselkraftstoff, und Haupteinspritzung eines zündträgen Kraftstoffs wie einer Dieselkraftstoff-Wasser-Emulsion oder Äthanol - siehe Fig. 2 -verwendet werden. In letzterem Fall werden die beiden verschiedenen Kraftstoffe in unterschiedlichen Vorratstanks 49, 50 bereitgestellt und hieraus mittels der jeweiligen Niederdruck-Speiseeinrichtung 17 bzw. 32 den angeschlossenen Kraftstoffwegen zugeführt. Im Fall gemäß Fig. 2 dient die Niederdruck-Speiseeinrichtung 32 gleichzeitig auch zur Versorgung der über jeweils eine Leitung 51 angeschlossenen Pumpenräume 7 der Einspritzpumpe 1. Im Fall gemäß Fig. 1 wird der zur Vor- und Haupteinspritzung dienende Kraftstoff in einem Vorratstank 52 bereitgestellt, aus dem die Pumpen 17/1 bzw. 32/1 beider Niederdruck-Speiseeinrichtungen 17, 32 Kraftstoff in die angeschlossenen Leitungswege fördern. In diesem Fall sind die Pumpenräume 7 der Einspritzpumpe 1 von der Niederdruck-Speiseeinrichtung 17 her über eine Zweigleitung 53 mit Kraftstoff versorgbar.The fuel injection device according to the invention can, regardless of its respective design, in principle either for pre-injection and main injection of the same fuel - see FIG. 1 - or for pre-injection of an ignitable fuel, in particular diesel fuel, and main injection of an ignitable fuel such as a diesel fuel-water emulsion or ethanol - see Fig. 2 - be used. In the latter case, the two different fuels are provided in different storage tanks 49, 50 and are fed therefrom to the connected fuel paths by means of the respective low-pressure feed device 17 or 32. In the case according to FIG. 2, the low-pressure feed device 32 also serves to supply the pump chambers 7 of the injection pump 1, each of which is connected via a line 51. In the case of FIG. 1, the fuel used for pre-injection and main injection is provided in a storage tank 52, from which the pumps 17/1 and 32/1 of both low-pressure feed devices 17, 32 deliver fuel into the connected line paths. In this case, the pump chambers 7 of the injection pump 1 can be supplied with fuel from the low-pressure feed device 17 via a branch line 53.

Claims (14)

  1. A fuel injection device for pilot and main injection via a respective two-needle injection valve into a combustion chamber of an internal combustion engine, with an injection pump with cam-controlled pump pistons rotatable for power control, and the respective pump chambers of the said piston pumps are fillable with fuel via a control bore joining at the side, and a valve spring-loaded in the closing direction is attached to the end of the said pump pistons, characterised in that
    - each two-needle injection valve (9) has two nozzle needles (18, 19) placed parallel to the axis and adjacent each other, the rear of each nozzle needle being acted upon by force in the closing direction via its own compression spring (20, 21) providing the opening pressure, and, when in the closing position supported on a seat they block associated nozzle bores (24, 25), and when in the opening position they open the said nozzle bores for injection,
    - the nozzle antechamber (28) of the pilot injection needle (18) is suppliable with pilot injection fuel from low pressure feed means (32) via a channel (30/1, 30/2, 30/3, 30/4), inside the valve, fitted with a non-return valve (31) allowing flow only in the feed direction,
    - a pump exit chamber (8) containing a delivery valve (14) and a compression spring (15) is attached to each pump chamber (7) of the injection pump (1), and a supply channel (10) inside the injection valve is attached directly or via an injection pipe (11) to the said pump exit chamber,
    - each delivery valve (14) acting as a pressure piston during the pump piston stroke expels the fuel present in the adjacent pipe passages (8, 11, 10), and at the same time blocks a filling bore (16) leading to the side of the pump exit chamber (8), and when each main injection is completed and the delivery valve (14) has been returned to the closed position the resulting cavity, corresponding to the injected main injection fuel quantity, in the downstream pipe passages (8, 11, 10) is refillable with main injection fuel by low pressure feed means (17) via the said filling bore, and
    - in each two-needle injection valve (9) a control piston (33) is provided freely movable axially between two final positions and is displaceable from its lower final position to another upper final position, when each main injection is completed, by pilot injection fuel supplied to its control antechamber (35) via a channel (38) from the nozzle antechamber (28) of the pilot injection needle (18), wherein the supply channel (10) is closed, and the said control piston is moved downwards from this upper final position when there is a controlled pressure build-up in the pump piston as a result of the waiting main injection fuel, wherein the pilot injection fuel waiting in its control antechamber (35) is displaced as a result of opening the pilot injection needle (18) and is injected in an appropriate quantity, and wherein a connection (36) to the nozzle antechamber (29) of the main injection needle (19) is opened by the control piston (33), thus causing the said main injection needle to be lifted by the main injection fuel advanced in the pump piston, and the said fuel to be injected to the point of pressure relief in the pump piston.
  2. A fuel injection device according to Claim 1, characterised in that the opening pressure of the pilot injection needle (18) is set lower than the pressure of the main injection needle (19) by way of the associated respective compression spring (20, 21).
  3. A fuel injection device according to Claim 1, characterised in that the control piston (33) is contained in the area between the two valve needles (18, 19) parallel to the axis thereto so as to be axially displaceable in a receiving bore (34) correspondingly widened at the bottom to form the control antechamber (35), and also widened further up at a distance of approximately the length of the control piston (33) from the said control-antechamber floor forming the lower stop to form a bridging chamber (36), and extending coaxially to the central supply channel (10) with a smaller diameter, wherein the passage from the said supply channel to the receiving bore (34) is formed by an insert sleeve (37), with the lower end surface thereof forming the upper stop for the control piston (33).
  4. A fuel injection device according to Claim 1 and 3, characterised in that the nozzle antechamber (28) of the pilot injection needle (18) is connected via a bore (38) to the control antechamber (35) of the control piston (33), and the bridging chamber (36) is connected to the nozzle antechamber (29) of the main injection needle (19), depending on the distance, by the chambers cutting into each other or by way of a bore.
  5. A fuel injection device according to any one of Claims 1 to 4, characterised in that the control piston is cylindrical with flat end surfaces chamfered where necessary at the edges.
  6. A fuel injection device according to any one of Claims 1 to 4, characterised in that the control piston (33) is in the form of a step piston to increase the pressure transmission, and comprises two cylinder sections (33/1, 33/2) with different diameters, wherein the cylinder section of smaller diameter (33/2) forms the lower control piston part, and the receiving bore (34) is adapted correspondingly in diameter thereto, wherein the said receiving bore is widened by a leakage chamber (43) at the level of the transition of the two cylinder sections, when viewed in the lower stop position of the control piston (33), and a leakage discharge channel (44) leads away from the said leakage chamber.
  7. A fuel injection device according to any one of Claims 1 to 4, characterised in that the control piston (33) is cylindrical with flat upper end surfaces, and also the receiving volume of the control antechamber (35) is extended by a blind hole bore (45) drilled from below into the control piston (33) and connected at a particular point via a transverse bore (46) to the periphery of the control piston (33), and the said blind hole bore is covered by the receiving bore (34) when the control piston (33) is in the upper final position, and comes into connection with a leakage chamber (47), formed by an annular extension of the receiving bore, with a leakage discharge pipe (48) extending therefrom when the control piston (33) moves downwards, and the pressure in the control pressure chamber (35) and the nozzle storage chamber (28) thereby fails, thus ending pilot injection and enabling the control piston (33) to be returned to its lower stop position.
  8. A fuel injection device according to Claim 1, characterised in that each of the two low pressure feed means (17, 32) has a delivery pump (17/1, 32/1), and the supply pressure P1, P2 thereof is set via a pressure restricting valve (17/2, 32/2) to approximately 2 to 4 bar, wherein, to ensure complete filling of the fuel chambers to be supplied and timely transfer of the control piston (33) to its upper final position, the supply pressure P2 for the pilot injection fuel is greater than the supply pressure for P1 for the main injection fuel.
  9. A fuel injection device according to Claim 8, characterised in that, when main injection is completed, to bring about complete filling of the nozzle antechamber (29) of the main injection needle (19) before closing of the supply channel (10) by the control piston (33), means are provided enabling substantially faster refilling of the main injection fuel in comparison with refilling of the pilot injection fuel.
  10. A fuel injection device according to Claim 9, characterised in that a throttle (39) is provided to form the said means in the pipe passage between the pilot injection fuel feed means (32) and the non-return valve (31), in particular at the start of the two-needle injection valve (9), and the transmission cross-section of the said throttle is substantially smaller than that of another throttle (40) in the pipe passage between the main injection fuel feed means (17) and the pump exit chamber (8), in particular at the start of the said pump exit chamber in the filling bore (16).
  11. A fuel injection device according to Claim 9, characterised in that to form the said means the control piston (33) has a blind hole bore (41) drilled from above and a transverse bore (42) leading from the said blind hole bore to the periphery and considerably smaller in diameter and in such an axial relative position, that when the control piston (33) is in the upper final position there is a throttled connection between the supply channel (10) and the bridging chamber (36) to the nozzle antechamber (29) of the main injection needle (19), but this transverse bore (42) is already covered by the receiving bore (34) after a small downward stroke of the control piston (33), and thus closed.
  12. A fuel injection device according to Claim 1, characterised in that the non-return valve (31) is fitted in an offset manner in the channel (30) inside the valve as close as possible before the joining thereof to the nozzle antechamber (28) of the pilot injection needle (18).
  13. A fuel injection device according to Claim 1, characterised by its use for the pilot and main injection of the same fuel.
  14. A fuel injection device according to Claim 1, characterised by its use for pilot injection of an ignitable fuel, in particular, diesel fuel, and main injection of a slow-to-ignite fuel, such as diesel water-emulsion fuel or ethanol, and the said fuels are provided in different storage tanks (49, 50) and are suppliable by means of the respective low pressure feed means (17, 32) to the associated fuel passages.
EP93120308A 1993-02-09 1993-12-16 Fuel injection device with pilot- and main-injection Expired - Lifetime EP0610585B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT224/93 1993-02-09
AT22493 1993-02-09

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EP0610585B1 true EP0610585B1 (en) 1996-09-04

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GB636080A (en) * 1947-11-18 1950-04-19 Kammer Engines Ltd Improvements in fuel injectors for internal combustion engines
DE3425460A1 (en) * 1983-08-26 1985-03-07 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION DEVICE FOR DEFINED PRELIMINARY AND MAIN INJECTION IN INTERNAL COMBUSTION ENGINES
DE3330771A1 (en) * 1983-08-26 1985-03-14 Robert Bosch Gmbh, 7000 Stuttgart FUEL INJECTION DEVICE WITH AUXILIARY PUMP FOR PRIME AND MAIN INJECTION
US4681073A (en) * 1986-02-05 1987-07-21 Deere & Company Fuel injection control valve
FR2595761B1 (en) * 1986-03-14 1988-05-13 Semt INJECTION DEVICE FOR AN INTERNAL COMBUSTION ENGINE, ALLOWING THE INJECTION OF TWO FUELS

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8683979B2 (en) 2011-02-14 2014-04-01 Caterpillar Inc. Dual fuel common rail system and engine using same

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EP0610585A1 (en) 1994-08-17
DE59303658D1 (en) 1996-10-10

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