WO2003081019A1 - Fuel injection valve for internal combustion engines - Google Patents

Fuel injection valve for internal combustion engines Download PDF

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Publication number
WO2003081019A1
WO2003081019A1 PCT/DE2003/000695 DE0300695W WO03081019A1 WO 2003081019 A1 WO2003081019 A1 WO 2003081019A1 DE 0300695 W DE0300695 W DE 0300695W WO 03081019 A1 WO03081019 A1 WO 03081019A1
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WO
WIPO (PCT)
Prior art keywords
valve
valve needle
needle
hollow
fuel injection
Prior art date
Application number
PCT/DE2003/000695
Other languages
German (de)
French (fr)
Inventor
Thomas Kuegler
Predrag Nunic
Detlev Potz
Original Assignee
Robert Bosch Gmbh
SANDER-POTZ, Maike
Potz, Wendelin
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, SANDER-POTZ, Maike, Potz, Wendelin filed Critical Robert Bosch Gmbh
Publication of WO2003081019A1 publication Critical patent/WO2003081019A1/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
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/18—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for
    • 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
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
    • F02M61/10—Other injectors with elongated valve bodies, i.e. of needle-valve type
    • F02M61/12—Other injectors with elongated valve bodies, i.e. of needle-valve type characterised by the provision of guiding or centring means for valve bodies
    • 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
    • F02M2200/46—Valves, e.g. injectors, with concentric valve bodies

Definitions

  • the invention is based on a fuel injection valve for internal combustion engines according to the preamble of claim 1.
  • a fuel injection valve for example from DE-OS 27 11 391 and comprises a valve body in which a hollow valve needle and a longitudinally displaceable valve needle are arranged in a bore.
  • the hollow valve needle At its end on the combustion chamber side, the hollow valve needle has a valve sealing surface with which it interacts with a valve seat formed in the valve body.
  • the valve needle has a valve sealing surface on its combustion chamber end, which cooperates with the same valve seat.
  • the valve needle is guided at least over part of its length in the hollow valve needle, so that it maintains a defined position with respect to the valve seat.
  • Several injection openings usually exit from the valve seat and open into the combustion chamber of the internal combustion engine.
  • Fuel can be injected under high pressure into the combustion chamber of the internal combustion engine through the injection openings, the opening of which is controlled by the hollow valve needle and the valve needle.
  • the known fuel injection valve has the disadvantage that the valve needle in the hollow valve needle is guided closely to the end of the hollow valve needle on the combustion chamber side in order to achieve an exact alignment with respect to the valve seat. Since the hollow valve needle can deform somewhat inwards due to the stresses when interacting with the valve seat, in particular if the valve seat is conically shaped, there is increased friction between the valve needle and the hollow valve needle and thus excessive wear.
  • the fuel injection valve according to the invention with the characterizing features of claim 1 has the advantage that the friction between the hollow valve needle and the valve needle always remains low, so that the service life of the fuel injection valve is significantly increased.
  • An exposure is provided between an end section of the valve needle and the hollow valve needle on the combustion chamber side, which ensures sufficient clearance of the valve needle at its end on the combustion chamber side.
  • the exposure is followed by a first guide section of the valve needle which is guided closely in the valve hollow needle, that is to say with little play.
  • a first guide section of the valve needle which is guided closely in the valve hollow needle, that is to say with little play.
  • the valve needle in addition to the first guide section, the valve needle also has a second guide section, with which it is also guided in the hollow valve needle and which is spaced apart from the first guide section. The valve needle can be guided more precisely in the hollow valve needle by means of two guide sections and at the same time the friction between these components.
  • the clearance of the valve needle in the hollow valve needle is greater on the second guide section than on the first guide section.
  • a tightly guided first guide section is important for the exact alignment of the valve needle. Since two guide sections of the valve needle are never exactly aligned in the bore, the play of the second guide section should be greater, so that there is no jamming of the valve needle in the hollow valve needle. It is particularly advantageous to provide an undercut between the two guide sections so that the valve needle is only guided in the guide sections and no friction occurs between them.
  • FIG. 1 shows a fuel injection valve in longitudinal section
  • Figure 2 is an enlargement of Figure 1 in the region of the valve seat and
  • FIG. 3 shows the same representation as Figure 2 of another embodiment. Description of the embodiment
  • a fuel injector is shown in longitudinal section.
  • the fuel injection valve comprises a valve body 1, in which a bore 3 with a longitudinal axis 8 is formed.
  • the bore 3 is delimited at its combustion chamber end by a conical valve seat 16, from which the outer injection openings 17 and inner injection openings 18 extend.
  • the inner injection openings 18 are arranged axially offset from the outer injection openings 17 with respect to the longitudinal axis 8 of the bore 3.
  • a hollow valve needle 10 is arranged to be longitudinally displaceable and is sealingly guided in the bore 3 in a section facing away from the combustion chamber.
  • the hollow valve needle 10 tapers towards the combustion chamber to form a pressure shoulder 14 and merges into a conical valve sealing surface 27 at its end on the combustion chamber side.
  • a pressure chamber 5 is formed between the hollow valve needle 10 and the wall of the bore 3, which is radially expanded at the level of the pressure shoulder 14. In this radial expansion of the pressure chamber 5 opens an inlet channel 7 formed in the valve body 1, via which the pressure chamber 5 can be filled with fuel under high pressure.
  • the hollow valve needle 10 has a longitudinal bore 11 in which a piston-shaped valve needle 12 is arranged to be longitudinally displaceable.
  • the valve needle 12 has a conical valve contact surface 29 at its combustion chamber end, which cooperates with the valve seat 16.
  • FIG. 2 shows an enlargement of FIG.
  • valve needle 12 covers the inner injection openings 18 when it is in contact with the valve seat 16, but not the outer injection openings 17.
  • An annular groove 35 is formed on the end of the valve needle 12 on the combustion chamber side, so that there is a pressure step 39, the surface of which lies opposite the valve seat 16.
  • the control of the injection of fuel through the injection openings 17, 18 works as follows: the hollow valve needle 10 interacts with the valve seat 16 in such a way that when the valve sealing surface 27 is in contact with the valve seat 16, the pressure chamber 5 is closed off against the injection openings 17, 18.
  • a closing force in the direction of the valve seat 16 acts on the hollow valve needle 10 and the valve needle 12 by means of a device (not shown in the drawing), so that the hollow valve needle 10 with its valve sealing surface 27 and the valve needle 12 with their valve contact surface 29 bear against the valve seat 16.
  • the closing force on the hollow valve needle 10 counteracts the hydraulic force by acting on the pressure shoulder 14.
  • Increasing the fuel pressure in the pressure chamber 5 or reducing the closing force on the hollow valve needle 10 results in a force that moves the hollow valve needle 10 away from the valve seat 16.
  • fuel can flow from the pressure chamber 5 to the outer injection openings 17 and is injected from there into the combustion chamber of the internal combustion engine.
  • the valve needle 12 remains temporarily in its
  • the closing force on the valve needle 12 is reduced to such an extent that the valve needle 12, driven by the hydraulic force on the pressure step 39, moves away from the valve seat 16 and releases the inner injection openings 18 .
  • the closing force on the valve needle 12 and the hollow valve needle 10 is increased again or the supply of fuel into the Pressure chamber 5 interrupted so that the valve needle 12 and the hollow valve needle 10 slide back into their closed position.
  • the valve needle 12 is not guided in the longitudinal bore 11 of the hollow valve needle 10 over the entire length of the valve needle 12, but only in certain sections.
  • the valve needle 12 therefore has a first guide section 22 at the end of the valve needle 12 on the combustion chamber side, which ends before the pressure step 39 and which has a play, that is to say a diameter difference, of only about 5 .mu.m with respect to the wall of the longitudinal bore 11. has to achieve an exact guidance of the valve needle 12 in the valve hollow needle 10.
  • This is essential for optimal injection, because usually a plurality of inner injection openings 18 are arranged distributed over the circumference of the valve body 1, so that even a small disaxation of the valve needle 12 leads to an uneven flow of fuel to the individual inner injection openings 18 and thus also to an uneven injection.
  • a second guide section 20 is formed on the valve needle 12, which has a play of approximately 0.03 mm to 0.05 mm with respect to the wall of the longitudinal bore 11.
  • the valve needle 12 is thus guided with the necessary precision in the hollow valve needle 10 without there being an excessive friction surface between these two components.
  • the valve needle 12 has an undercut between the first guide section 22 and the second guide section 20, so that there is a play of approximately 0.1 mm in this area between the valve needle 12 and the wall of the longitudinal bore 11.
  • an exposure 32 adjoins the first guide section 22, which extends as far as the pressure step 39.
  • a clearance D of 0.04 mm to 0.15 mm, preferably less than 0.1 mm, remains between the wall of the longitudinal bore 11 and the valve needle 12. This prevents excessive friction Valve needle 12 in the longitudinal bore 11: In its closed position, the hollow valve needle 10 is pressed against the valve seat 16 with a relatively large closing force. This results in a slight radial indentation of the hollow valve needle 10 in the region of the valve sealing surface 27, which is purely elastic.
  • FIG. 3 shows a further exemplary embodiment, the section shown corresponding to that of FIG. 2.
  • the exposure 32 is not realized here by reducing the diameter of the valve needle 12, but rather by radially widening the longitudinal bore 11. This also results in a reduction in wear in this area with a good and exact guidance of the valve needle 12.
  • the first guide section In this case, 22 extends to the printed paragraph 39.

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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

A fuel injection valve for internal combustion engines, comprising a valve body (1) whereby a valve cannula (10) is arranged therein in a bore (3) such that it is longitudinally displaceable. The valve cannula (10) is provided with a longitudinal bore (11) and a valve sealing surface (27) which is disposed on the combustion- chamber end thereof and cooperates with a valve seat (16) disposed on the combustion chamber end of the bore (2). A valve needle (12) is arranged inside the valve cannula (10) and also cooperates with the valve seat (16) by means of a valve bearing surface (29) embodied on the combustion-chamber end thereof and which is guided at least along part of the length thereof in the valve cannula (10). An area between the combustion-chamber end section of the valve needle (12) and the longitudinal bore is uncovered (32).

Description

Kraftstoffeinspritzventil für BrennkraftmaschinenFuel injection valve for internal combustion engines
Stand der TechnikState of the art
Die Erfindung geht von einem Kraftstoffeinspritzventil für Brennkraftmaschinen nach der Gattung des Patentanspruchs 1 aus. Ein solches Kraftstoffeinspritzventil ist beispielsweise aus der Schrift DE-OS 27 11 391 bekannt und umfasst einen Ventilkörper, in dem in einer Bohrung eine Ventilhohlnadel und in dieser eine längsverschiebbare Ventilnadel angeordnet sind. An ihrem brennraumseitigen Ende weist die Ventilhohlnadel eine Ventildichtfläche auf, mit der sie mit einem im Ventilkörper ausgebildeten Ventilsitz zusammenwirkt. Ebenso weist die Ventilnadel an ihrem brennraumseitigen Ende eine Ventildichtfläche auf, die mit demselben Ventilsitz zusammenwirkt. Die Ventilnadel wird hierbei zumindest auf einem Teil ihrer Länge in der Ventilhohlnadel geführt, so dass sie zum Ventilsitz eine definierte Lage einhält. Vom Ventilsitz gehen meist mehrere Einspritzöffnungen aus, die in den Brennraum der Brennkraftmaschine münden. Durch die Einspritzöffnungen kann Kraftstoff unter hohem Druck in den Brennraum der Brennkraftmaschine eingespritzt werden, wobei deren Öffnung durch die Ventilhohlnadel und die Ventilnadel gesteuert wird. Das bekannte Kraftstoffeinspritzventil weist hierbei jedoch den Nachteil auf, dass die Ventilnadel in der Ventilhohlnadel bis zum brennraumseitigen Ende der Ventilhohlnadel eng geführt wird, um eine exakte Ausrichtung bezüglich des Ven- tilsitzes zu erreichen. Da sich die Ventilhohlnadel aufgrund der Belastungen beim Zusammenwirken mit dem Ventilsitz etwas nach innen verformen kann, insbesondere dann, wenn der Ventilsitz konisch geformt ist, kommt es zwischen der Ventilnadel und der Ventilhohlnadel zu erhöhter Reibung und damit zu übermäßigem Verschleiß.The invention is based on a fuel injection valve for internal combustion engines according to the preamble of claim 1. Such a fuel injection valve is known for example from DE-OS 27 11 391 and comprises a valve body in which a hollow valve needle and a longitudinally displaceable valve needle are arranged in a bore. At its end on the combustion chamber side, the hollow valve needle has a valve sealing surface with which it interacts with a valve seat formed in the valve body. Likewise, the valve needle has a valve sealing surface on its combustion chamber end, which cooperates with the same valve seat. The valve needle is guided at least over part of its length in the hollow valve needle, so that it maintains a defined position with respect to the valve seat. Several injection openings usually exit from the valve seat and open into the combustion chamber of the internal combustion engine. Fuel can be injected under high pressure into the combustion chamber of the internal combustion engine through the injection openings, the opening of which is controlled by the hollow valve needle and the valve needle. However, the known fuel injection valve has the disadvantage that the valve needle in the hollow valve needle is guided closely to the end of the hollow valve needle on the combustion chamber side in order to achieve an exact alignment with respect to the valve seat. Since the hollow valve needle can deform somewhat inwards due to the stresses when interacting with the valve seat, in particular if the valve seat is conically shaped, there is increased friction between the valve needle and the hollow valve needle and thus excessive wear.
Vorteile der ErfindungAdvantages of the invention
Das erfindungsgemäße Kraftstoffeinspritzventil mit den kenn- zeichnenden Merkmalen des Patentanspruchs 1 weist demgegenüber den Vorteil auf, dass die Reibung zwischen der Ventilhohlnadel und der Ventilnadel stets niedrig bleibt, so dass sich die Lebensdauer des Kraftstoffeinspritzventils deutlich erhöht. Zwischen einem brennraumseitigen Endabschnitt der Ventilnadel und der Ventilhohlnadel ist eine Freilegung vorgesehen, die ein ausreichendes Spiel der Ventilnadel an ihrem brennraumseitigen Ende sicherstellt.The fuel injection valve according to the invention with the characterizing features of claim 1 has the advantage that the friction between the hollow valve needle and the valve needle always remains low, so that the service life of the fuel injection valve is significantly increased. An exposure is provided between an end section of the valve needle and the hollow valve needle on the combustion chamber side, which ensures sufficient clearance of the valve needle at its end on the combustion chamber side.
Durch die Unteransprüche sind vorteilhafte Ausgestaltungen des Gegenstandes der Erfindung möglich.Advantageous embodiments of the subject matter of the invention are possible through the subclaims.
In einer ersten vorteilhaften Ausgestaltung schließt sich brennraumabgewandt an die Freilegung ein erster Führungsabschnitt der Ventilnadel an, der in der Ventilhohlnadel eng, also mit geringem Spiel, geführt ist. Hierdurch bleibt die geringe Reibung zwischen der Ventilhohlnadel und der Ventilnadel erhalten, da die Verformung nur am äußersten brennraumseitigen Ende der Ventilhohlnadel auftritt. Andererseits ist eine exakte Führung der Ventilnadel im Bezug auf den Ventilsitz gewährleistet und damit auch eine gleichmäßige Einspritzung durch sämtliche Einspritzöffnungen. In einer weiteren vorteilhaften Ausgestaltung weist die Ventilnadel neben dem ersten Führungsabschnitt auch einen zweiten Führungsabschnitt auf, mit dem sie ebenfalls in der Ven- tilhohlnadel geführt ist und der zum ersten Führungsabschnitt beabstandet ist. Durch zwei Führungsabschnitte lässt sich die Ventilnadel exakter in der Ventilhohlnadel führen und gleichzeitig die Reibung zwischen diesen Bauteilen.In a first advantageous embodiment, facing away from the combustion chamber, the exposure is followed by a first guide section of the valve needle which is guided closely in the valve hollow needle, that is to say with little play. As a result, the low friction between the hollow valve needle and the valve needle is retained, since the deformation occurs only at the outermost end of the hollow valve needle on the combustion chamber side. On the other hand, an exact guidance of the valve needle in relation to the valve seat is guaranteed and thus also a uniform injection through all injection openings. In a further advantageous embodiment, in addition to the first guide section, the valve needle also has a second guide section, with which it is also guided in the hollow valve needle and which is spaced apart from the first guide section. The valve needle can be guided more precisely in the hollow valve needle by means of two guide sections and at the same time the friction between these components.
In einer weiteren vorteilhaften Ausgestaltung ist das Spiel der Ventilnadel in der Ventilhohlnadel am zweiten Führungsabschnitt größer als am ersten Führungsabschnitt. Für die exakte Ausrichtung der Ventilnadel ist ein eng geführter erster Führungsabschnitt wichtig. Da zwei Führungsabschnitte der Ventilnadel nie exakt in der Bohrung fluchten, sollte das Spiel des zweiten Führungsabschnitts größer sein, so dass es zu keinem Klemmen der Ventilnadel in der Ventilhohlnadel kommt. Besonders vorteilhaft ist dabei, zwischen den beiden Führungsabschnitten einen Freistich vorzusehen, so dass die Ventilnadel nur in den Führungsabschnitten geführt wird und dazwischen keine Reibung auftritt.In a further advantageous embodiment, the clearance of the valve needle in the hollow valve needle is greater on the second guide section than on the first guide section. A tightly guided first guide section is important for the exact alignment of the valve needle. Since two guide sections of the valve needle are never exactly aligned in the bore, the play of the second guide section should be greater, so that there is no jamming of the valve needle in the hollow valve needle. It is particularly advantageous to provide an undercut between the two guide sections so that the valve needle is only guided in the guide sections and no friction occurs between them.
Weitere Vorteile und vorteilhafte Ausgestaltungen des Gegenstandes der Erfindung sind der Zeichnung und der Be- Schreibung entnehmbar.Further advantages and advantageous refinements of the subject matter of the invention can be found in the drawing and the description.
Zeichnungdrawing
In der Zeichnung ist ein Ausführungsbeispiel des erfindungs- gemäßen Kraftstoffeinspritzventils dargestellt. Es zeigtAn exemplary embodiment of the fuel injection valve according to the invention is shown in the drawing. It shows
Figur 1 ein Kraftstoffeinspritzventil im Längsschnitt,FIG. 1 shows a fuel injection valve in longitudinal section,
Figur 2 eine Vergrößerung von Figur 1 im Bereich des Ventilsitzes undFigure 2 is an enlargement of Figure 1 in the region of the valve seat and
Figur 3 dieselbe Darstellung wie Figur 2 eines weiteren Ausführungsbeispiels. Beschreibung des AusführungsbeispielsFigure 3 shows the same representation as Figure 2 of another embodiment. Description of the embodiment
In Figur 1 ist ein Kraftstoffeinspritzventil im Längsschnitt dargestellt. Das Kraftstoffeinspritzventil umfasst einen Ventilkörper 1, in dem eine Bohrung 3 mit einer Längsachse 8 ausgebildet ist. Die Bohrung 3 wird an ihrem brennraumseitigen Ende von einem konischen Ventilsitz 16 begrenzt, von dem äußere Einspritzöffnungen 17 und innere Einspritzöffnungen 18 abgehen. Die inneren Einspritzöffnungen 18 sind dabei be- züglich der Längsachse 8 der Bohrung 3 axial versetzt zu den äußeren Einspritzöffnungen 17 angeordnet. In der Bohrung 3 ist eine Ventilhohlnadel 10 längsverschiebbar angeordnet, die in einem brennraumabgewandten Abschnitt in der Bohrung 3 dichtend geführt ist. Die Ventilhohlnadel 10 verjüngt sich ausgehend von ihrem geführten Abschnitt dem Brennraum zu unter Bildung einer Druckschulter 14 und geht an ihrem brennraumseitigen Ende in eine konische Ventildichtfläche 27 ü- ber. Zwischen der Ventilhohlnadel 10 und der Wand der Bohrung 3 ist ein Druckraum 5 ausgebildet, der auf Höhe der Druckschulter 14 radial erweitert ist. In diese radiale Erweiterung des Druckraums 5 mündet ein im Ventilkörper 1 ausgebildeter Zulaufkanal 7 , über den der Druckraum 5 mit Kraftstoff unter hohem Druck befüllbar ist. Die Ventilhohlnadel 10 weist eine Längsbohrung 11 auf, in der eine kolben- förmige Ventilnadel 12 längsverschiebbar angeordnet ist. Die Ventilnadel 12 weist an ihrem brennraumseitigen Ende eine konische Ventilanlägefläche 29 auf, die mit dem Ventilsitz 16 zusammenwirkt. Figur 2 zeigt hierzu eine Vergrößerung von Figur 1 im Bereich des Ventilsitzes 16. Die Ventilnadel 12 verdeckt bei Anlage am Ventilsitz 16 die inneren Einspritzöffnungen 18, nicht jedoch die äußeren Einspritzöffnungen 17. Am brennraumseitigen Ende der Ventilnadel 12 ist eine Ringnut 35 ausgebildet, so dass sich ein Druckabsatz 39 ergibt, dessen Fläche dem Ventilsitz 16 gegenüberliegt. Die Steuerung der Einspritzung von Kraftstoff durch die Einspritzöffnungen 17, 18 funktioniert wie folgt: Die Ventilhohlnadel 10 wirkt in der Weise mit dem Ventilsitz 16 zusammen, dass bei Anlage der Ventildichtfläche 27 am Ventilsitz 16 der Druckraum 5 gegen die Einspritzöffnungen 17, 18 verschlossen ist. Auf die Ventilhohlnadel 10 und die Ventilnadel 12 wirkt durch eine in der Zeichnung nicht dargestellte Vorrichtung eine Schließkraft in Richtung des Ventilsitzes 16, so dass die Ventilhohlnadel 10 mit ihrer Ventildichtflä- ehe 27 und die Ventilnadel 12 mit ihrer Ventilanlagefläche 29 am Ventilsitz 16 anliegen. Der Schließkraft auf die Ventilhohlnadel 10 wirkt die hydraulische Kraft durch Beaufschlagung der Druckschulter 14 entgegen. Durch eine Erhöhung des Kraftstoffdrucks im Druckraum 5 oder durch eine Reduzie- rung der Schließkraft auf die Ventilhohlnadel 10 ergibt sich eine resultierende Kraft, die die Ventilhohlnadel 10 vom Ventilsitz 16 wegbewegt. Aus dem Druckraum 5 kann dadurch Kraftstoff den äußeren Einspritzöffnungen 17 zufließen und wird von dort in den Brennraum der Brennkraftmaschine einge- spritzt. Die Ventilnadel 12 verbleibt vorläufig in ihrerIn Figure 1, a fuel injector is shown in longitudinal section. The fuel injection valve comprises a valve body 1, in which a bore 3 with a longitudinal axis 8 is formed. The bore 3 is delimited at its combustion chamber end by a conical valve seat 16, from which the outer injection openings 17 and inner injection openings 18 extend. The inner injection openings 18 are arranged axially offset from the outer injection openings 17 with respect to the longitudinal axis 8 of the bore 3. In the bore 3, a hollow valve needle 10 is arranged to be longitudinally displaceable and is sealingly guided in the bore 3 in a section facing away from the combustion chamber. Starting from its guided section, the hollow valve needle 10 tapers towards the combustion chamber to form a pressure shoulder 14 and merges into a conical valve sealing surface 27 at its end on the combustion chamber side. A pressure chamber 5 is formed between the hollow valve needle 10 and the wall of the bore 3, which is radially expanded at the level of the pressure shoulder 14. In this radial expansion of the pressure chamber 5 opens an inlet channel 7 formed in the valve body 1, via which the pressure chamber 5 can be filled with fuel under high pressure. The hollow valve needle 10 has a longitudinal bore 11 in which a piston-shaped valve needle 12 is arranged to be longitudinally displaceable. The valve needle 12 has a conical valve contact surface 29 at its combustion chamber end, which cooperates with the valve seat 16. FIG. 2 shows an enlargement of FIG. 1 in the area of the valve seat 16. The valve needle 12 covers the inner injection openings 18 when it is in contact with the valve seat 16, but not the outer injection openings 17. An annular groove 35 is formed on the end of the valve needle 12 on the combustion chamber side, so that there is a pressure step 39, the surface of which lies opposite the valve seat 16. The control of the injection of fuel through the injection openings 17, 18 works as follows: the hollow valve needle 10 interacts with the valve seat 16 in such a way that when the valve sealing surface 27 is in contact with the valve seat 16, the pressure chamber 5 is closed off against the injection openings 17, 18. A closing force in the direction of the valve seat 16 acts on the hollow valve needle 10 and the valve needle 12 by means of a device (not shown in the drawing), so that the hollow valve needle 10 with its valve sealing surface 27 and the valve needle 12 with their valve contact surface 29 bear against the valve seat 16. The closing force on the hollow valve needle 10 counteracts the hydraulic force by acting on the pressure shoulder 14. Increasing the fuel pressure in the pressure chamber 5 or reducing the closing force on the hollow valve needle 10 results in a force that moves the hollow valve needle 10 away from the valve seat 16. As a result, fuel can flow from the pressure chamber 5 to the outer injection openings 17 and is injected from there into the combustion chamber of the internal combustion engine. The valve needle 12 remains temporarily in its
Schließstellung, da sie erst mit dem Abheben der Ventilhohlnadel 10 vom Kraftstoffdruck des Druckraums 5 beaufschlagt wird, wodurch sich eine hydraulische Kraft auf den Druckabsatz 39 ergibt. Soll die Einspritzung von Kraftstoff nur durch die äußeren Einspritzöffnungen 17 erfolgen, so wird die Schließkraft auf die Ventilnadel 12 so hoch gehalten, dass die Ventilnadel 12, trotz der hydraulischen Kraft auf den Druckabsatz 39, in ihrer Schließstellung bleibt. Soll hingegen durch sämtliche Einspritzöffnungen 17, 18 einge- spritzt werden, so wird die Schließkraft auf die Ventilnadel 12 soweit reduziert, dass sich die Ventilnadel 12, angetrieben durch die hydraulische Kraft auf den Druckabsatz 39, vom Ventilsitz 16 wegbewegt und die inneren Einspritzöffnungen 18 freigibt. Zur Beendigung der Einspritzung wird die Schließkraft auf die Ventilnadel 12 und die Ventilhohlnadel 10 wieder erhöht oder die Zufuhr von Kraftstoff in den Druckraum 5 unterbrochen, so dass die Ventilnadel 12 und die Ventilhohlnadel 10 zurück in ihre Schließstellung gleiten.Closed position, since it is only acted upon by the lifting of the valve hollow needle 10 from the fuel pressure of the pressure chamber 5, which results in a hydraulic force on the pressure step 39. If the injection of fuel is to take place only through the outer injection openings 17, the closing force on the valve needle 12 is kept so high that the valve needle 12 remains in its closed position despite the hydraulic force on the pressure step 39. If, on the other hand, injection is to take place through all the injection openings 17, 18, the closing force on the valve needle 12 is reduced to such an extent that the valve needle 12, driven by the hydraulic force on the pressure step 39, moves away from the valve seat 16 and releases the inner injection openings 18 , To end the injection, the closing force on the valve needle 12 and the hollow valve needle 10 is increased again or the supply of fuel into the Pressure chamber 5 interrupted so that the valve needle 12 and the hollow valve needle 10 slide back into their closed position.
Die Führung der Ventilnadel 12 in der Längsbohrung 11 der Ventilhohlnadel 10 erfolgt nicht über die gesamte Länge der Ventilnadel 12, sondern nur in bestimmten Abschnitten. Die Ventilnadel 12 weist deshalb einen ersten Führungsabschnitt 22 am brennraumseitigen Ende der Ventilnadel 12 auf, der vor dem Druckabsatz 39 endet und der bezüglich der Wand der Längsbohrung 11 ein Spiel, also eine Durchmesserdifferenz, von nur etwa 5 ßm. aufweist, um eine exakte Führung der Ventilnadel 12 in der Ventilhohlnadel 10 zu erreichen. Dies ist für eine optimale Einspritzung unerlässlich, denn in der Regel sind mehrere innere Einspritzöffnungen 18 über den Um- fang des Ventilkörpers 1 verteilt angeordnet, so dass bereits eine kleine Desaxierung der Ventilnadel 12 zu einem ungleichmäßigen Zuströmen von Kraftstoff zu den einzelnen inneren Einspritzöffnungen 18 führt und damit auch zu einer ungleichmäßigen Einspritzung. An der Ventilnadel 12 ist dar- über hinaus ein zweiter Führungsabschnitt 20 ausgebildet, der gegenüber der Wand der Längsbohrung 11 ein Spiel von etwa 0,03 mm bis 0,05 mm aufweist. Die Ventilnadel 12 wird so mit der nötigen Präzision in der Ventilhohlnadel 10 geführt, ohne dass eine übergroße Reibungsfläche zwischen diesen bei- den Bauteilen vorliegt.The valve needle 12 is not guided in the longitudinal bore 11 of the hollow valve needle 10 over the entire length of the valve needle 12, but only in certain sections. The valve needle 12 therefore has a first guide section 22 at the end of the valve needle 12 on the combustion chamber side, which ends before the pressure step 39 and which has a play, that is to say a diameter difference, of only about 5 .mu.m with respect to the wall of the longitudinal bore 11. has to achieve an exact guidance of the valve needle 12 in the valve hollow needle 10. This is essential for optimal injection, because usually a plurality of inner injection openings 18 are arranged distributed over the circumference of the valve body 1, so that even a small disaxation of the valve needle 12 leads to an uneven flow of fuel to the individual inner injection openings 18 and thus also to an uneven injection. Furthermore, a second guide section 20 is formed on the valve needle 12, which has a play of approximately 0.03 mm to 0.05 mm with respect to the wall of the longitudinal bore 11. The valve needle 12 is thus guided with the necessary precision in the hollow valve needle 10 without there being an excessive friction surface between these two components.
Zwischen dem ersten Führungsabschnitt 22 und dem zweiten Führungsabschnitt 20 weist die Ventilnadel 12 einen Freistich auf, so dass in diesem Bereich zwischen der Ventilna- del 12 und der Wand der Langsbohrung 11 ein Spiel von etwa 0,1 mm vorhanden ist. Am brennraumseitigen Endabschnitt schließt sich an den ersten Führungsabschnitt 22 eine Freilegung 32 an, die bis zum Druckabsatz 39 reicht. Zwischen der Wand der Längsbohrung 11 und der Ventilnadel 12 ver- bleibt ein Spiel D von 0,04 mm bis 0,15 mm, vorzugsweise weniger als 0,1 mm. Dies verhindert eine übergroße Reibung der Ventilnadel 12 in der Längsbohrung 11: In ihrer Schließstellung wird die Ventilhohlnadel 10 mit einer relativ großen Schließkraft gegen den Ventilsitz 16 gedrückt. Dadurch kommt es zu einer leichten radialen Einformung der Ventilhohlnadel 10 im Bereich der Ventildichtfläche 27, die rein elastisch erfolgt. Bei einem geringen Spiel, wie es im ersten Führungsabschnitt 22 der Ventilnadel 12 herrscht, würde dies zu einer übergroßen Reibung der Ventilnadel 12 in der Längsbohrung 11 führen. Durch die Freilegung 32 verbleibt ein genü- gend großer Ringspalt zwischen der Ventilnadel 12 und der Wand der Längsbohrung 11, so dass es zu keiner übermäßigen Reibung oder gar zum Fressen der Ventilnadel 12 kommt.The valve needle 12 has an undercut between the first guide section 22 and the second guide section 20, so that there is a play of approximately 0.1 mm in this area between the valve needle 12 and the wall of the longitudinal bore 11. At the end section on the combustion chamber side, an exposure 32 adjoins the first guide section 22, which extends as far as the pressure step 39. A clearance D of 0.04 mm to 0.15 mm, preferably less than 0.1 mm, remains between the wall of the longitudinal bore 11 and the valve needle 12. This prevents excessive friction Valve needle 12 in the longitudinal bore 11: In its closed position, the hollow valve needle 10 is pressed against the valve seat 16 with a relatively large closing force. This results in a slight radial indentation of the hollow valve needle 10 in the region of the valve sealing surface 27, which is purely elastic. With a slight play, as prevails in the first guide section 22 of the valve needle 12, this would lead to excessive friction of the valve needle 12 in the longitudinal bore 11. The exposure 32 leaves a sufficiently large annular gap between the valve needle 12 and the wall of the longitudinal bore 11, so that there is no excessive friction or even seizure of the valve needle 12.
In Figur 3 ist ein weiteres Ausführungsbeispiel dargestellt, wobei der gezeigte Ausschnitt dem von Figur 2 entspricht.FIG. 3 shows a further exemplary embodiment, the section shown corresponding to that of FIG. 2.
Die Freilegung 32 ist hier nicht durch eine Verminderung des Durchmessers der Ventilnadel 12 realisiert, sondern durch eine radiale Erweiterung der Längsbohrung 11. Hierdurch ergibt sich ebenfalls eine Verschleißminderung in diesem Be- reich bei einer gleichzeitig guten und exakten Führung der Ventilnadel 12. Der erste Führungsabschnitt 22 reicht in diesem Fall bis zum Druckabsatz 39. The exposure 32 is not realized here by reducing the diameter of the valve needle 12, but rather by radially widening the longitudinal bore 11. This also results in a reduction in wear in this area with a good and exact guidance of the valve needle 12. The first guide section In this case, 22 extends to the printed paragraph 39.

Claims

Ansprüche Expectations
1. Kraftstoffeinspritzventil für Brennkraftmaschinen mit einem Ventilkörper (1) , in dem in einer Bohrung (3) eine Ventilhohlnadel (10) längsverschiebbar angeordnet ist, welche eine Längsbohrung (11) und an ihrem brennraumseitigen Ende eine Ventildichtfläche (27) aufweist, die mit einem am brennraumseitigen Ende der Bohrung (3) angeordneten Ventilsitz (16) zusammenwirkt, und mit einer in der Längsbohrung (11) der Ventilhohlnadel (10) angeordneten Ventilnadel (12) , die mit einer an ihrem brennraumseitigen Ende ausgebildeten Ventilanlagefläche (29) ebenfalls mit dem Ventilsitz (16) zusammenwirkt und die zumindest auf einem Teil ihrer Länge in der Ventilhohlnadel (10) geführt ist, dadurch gekennzeichnet, dass zwischen dem brennraumseitigen Endabschnitt der Ventilnadel (12) und der Wand der Längsbohrung (11) eine Freilegung (32) vor- gesehen ist.1.Fuel injection valve for internal combustion engines with a valve body (1), in which a hollow valve needle (10) is arranged in a bore (3) in a longitudinally displaceable manner, which has a longitudinal bore (11) and at its combustion chamber end a valve sealing surface (27) with a at the combustion chamber end of the bore (3) arranged valve seat (16) cooperates, and with a valve needle (12) arranged in the longitudinal bore (11) of the hollow valve needle (10), which also has a valve contact surface (29) formed on its combustion chamber end Valve seat (16) cooperates and which is guided at least over part of its length in the hollow valve needle (10), characterized in that an exposure (32) is provided between the end section of the valve needle (12) on the combustion chamber side and the wall of the longitudinal bore (11). is seen.
2. Kraftstoffeinspritzventil nach Anspruch 1, dadurch gekennzeichnet, dass die Freilegung (32) durch eine Verminderung des Durchmessers der Ventilnadel (12) gebildet ist.2. Fuel injection valve according to claim 1, characterized in that the exposure (32) is formed by a reduction in the diameter of the valve needle (12).
3. Kraftstoffeinspritzventil nach Anspruch 1, dadurch gekennzeichnet, dass die Freilegung (32) durch eine Erweiterung der Längsbohrung (11) der Ventilhohlnadel (10) gebildet ist. 3. Fuel injection valve according to claim 1, characterized in that the exposure (32) is formed by an expansion of the longitudinal bore (11) of the hollow valve needle (10).
4. Kraftstoffeinspritzventil nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass sich dem Ventilsitz4. Fuel injection valve according to one of claims 1 to 3, characterized in that the valve seat
(16) abgewandt an die Freilegung (32) ein erster Führungsabschnitt (22) der Ventilnadel (12) anschließt, der in der Ventilhohlnadel (10) eng geführt ist.(16) facing away from the exposure (32) is a first guide section (22) of the valve needle (12), which is closely guided in the hollow valve needle (10).
5. Kraftstoffeinspritzventil nach Anspruch 4, dadurch gekennzeichnet, dass die Ventilnadel (12) einen zweiten Führungsabschnitt (20) aufweist, mit dem sie ebenfalls in der Ventilhohlnadel (10) geführt ist.5. Fuel injection valve according to claim 4, characterized in that the valve needle (12) has a second guide section (20) with which it is also guided in the hollow valve needle (10).
6. Kraftstoffeinspritzventil nach Anspruch 5, dadurch gekennzeichnet, dass das Spiel der Ventilnadel (12) in der Längsbohrung (11) der Ventilhohlnadel (10) am zweiten Führungsabschnitt (20) größer ist als am ersten Führungsabschnitt (22) .6. Fuel injection valve according to claim 5, characterized in that the play of the valve needle (12) in the longitudinal bore (11) of the hollow valve needle (10) on the second guide section (20) is greater than on the first guide section (22).
7. Kraftstoffeinspritzventil nach Anspruch 5, dadurch gekennzeichnet, dass zwischen dem ersten Führungsabschnitt (22) und dem zweiten Führungsabschnitt (20) ein Freistich vorgesehen ist. 7. Fuel injection valve according to claim 5, characterized in that an undercut is provided between the first guide section (22) and the second guide section (20).
PCT/DE2003/000695 2002-03-26 2003-03-03 Fuel injection valve for internal combustion engines WO2003081019A1 (en)

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DE2002113384 DE10213384A1 (en) 2002-03-26 2002-03-26 Fuel injection valve for internal combustion engines

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Cited By (1)

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Publication number Priority date Publication date Assignee Title
US10428777B2 (en) 2015-06-09 2019-10-01 Denso Corporation Fuel injection device

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US1834061A (en) * 1930-04-30 1931-12-01 Westinghouse Electric & Mfg Co Fuel nozzle
DE2711391A1 (en) 1977-03-16 1978-09-21 Bosch Gmbh Robert FUEL INJECTOR
US4202500A (en) * 1977-03-09 1980-05-13 Maschinenfabrik Augsburg-Nuernberg Aktiengesellschaft Multi-hole injection nozzle
DE4115477A1 (en) * 1990-05-17 1991-11-21 Avl Verbrennungskraft Messtech Injection nozzle for IC engine - has hollow needle controlling first group of injection holes and loaded by first spring towards its closure position
DE4115457A1 (en) * 1990-05-17 1991-11-21 Avl Verbrennungskraft Messtech Injection nozzle for IC engine - incorporates hollow needle controlling first group of injection holes and loaded towards closure position by spring
JPH10274128A (en) * 1997-03-31 1998-10-13 Aisan Ind Co Ltd Fuel injection valve
DE19834867A1 (en) * 1997-08-07 1999-02-11 Avl List Gmbh Injector for common-rail direct-injection diesel engines
DE10038054A1 (en) * 1999-08-05 2001-02-15 Avl List Gmbh Cam-controlled injection unit for internal combustion engine; has two injector needles, where one has control piston for pressure chamber, in which pressure is controlled by valve in balance line
DE10040738A1 (en) * 1999-08-19 2001-03-15 Avl List Gmbh Injection device for internal combustion engine has dual needle nozzle injection nozzle with two nozzle needles alternately operable in partial load mode, simultaneously in full load operation

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Publication number Priority date Publication date Assignee Title
US1834061A (en) * 1930-04-30 1931-12-01 Westinghouse Electric & Mfg Co Fuel nozzle
US4202500A (en) * 1977-03-09 1980-05-13 Maschinenfabrik Augsburg-Nuernberg Aktiengesellschaft Multi-hole injection nozzle
DE2711391A1 (en) 1977-03-16 1978-09-21 Bosch Gmbh Robert FUEL INJECTOR
DE4115477A1 (en) * 1990-05-17 1991-11-21 Avl Verbrennungskraft Messtech Injection nozzle for IC engine - has hollow needle controlling first group of injection holes and loaded by first spring towards its closure position
DE4115457A1 (en) * 1990-05-17 1991-11-21 Avl Verbrennungskraft Messtech Injection nozzle for IC engine - incorporates hollow needle controlling first group of injection holes and loaded towards closure position by spring
JPH10274128A (en) * 1997-03-31 1998-10-13 Aisan Ind Co Ltd Fuel injection valve
DE19834867A1 (en) * 1997-08-07 1999-02-11 Avl List Gmbh Injector for common-rail direct-injection diesel engines
DE10038054A1 (en) * 1999-08-05 2001-02-15 Avl List Gmbh Cam-controlled injection unit for internal combustion engine; has two injector needles, where one has control piston for pressure chamber, in which pressure is controlled by valve in balance line
DE10040738A1 (en) * 1999-08-19 2001-03-15 Avl List Gmbh Injection device for internal combustion engine has dual needle nozzle injection nozzle with two nozzle needles alternately operable in partial load mode, simultaneously in full load operation

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10428777B2 (en) 2015-06-09 2019-10-01 Denso Corporation Fuel injection device

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