EP2199590B1 - Fuel injector - Google Patents

Fuel injector Download PDF

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Publication number
EP2199590B1
EP2199590B1 EP09169844.9A EP09169844A EP2199590B1 EP 2199590 B1 EP2199590 B1 EP 2199590B1 EP 09169844 A EP09169844 A EP 09169844A EP 2199590 B1 EP2199590 B1 EP 2199590B1
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EP
European Patent Office
Prior art keywords
nozzle needle
actuator
bore
fuel injector
closing element
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.)
Not-in-force
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EP09169844.9A
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German (de)
French (fr)
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EP2199590A1 (en
Inventor
Michael Kurz
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP2199590A1 publication Critical patent/EP2199590A1/en
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Publication of EP2199590B1 publication Critical patent/EP2199590B1/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
    • F02M51/00—Fuel-injection apparatus characterised by being operated electrically
    • F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
    • F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • 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
    • F02M2200/30—Fuel-injection apparatus having mechanical parts, the movement of which is damped
    • F02M2200/306—Fuel-injection apparatus having mechanical parts, the movement of which is damped using mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/30—Fuel-injection apparatus having mechanical parts, the movement of which is damped
    • F02M2200/308—Fuel-injection apparatus having mechanical parts, the movement of which is damped using pneumatic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/70—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger
    • F02M2200/703—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/02—Fuel-injection apparatus having several injectors fed by a common pumping element, or having several pumping elements feeding a common injector; Fuel-injection apparatus having provisions for cutting-out pumps, pumping elements, or injectors; Fuel-injection apparatus having provisions for variably interconnecting pumping elements and injectors alternatively
    • F02M63/0225—Fuel-injection apparatus having a common rail feeding several injectors ; Means for varying pressure in common rails; Pumps feeding common rails

Definitions

  • the invention relates to a fuel injector with arranged in an injector high-pressure chamber, which is connectable to a high pressure fuel source and controlled by a Schheßghed or a nozzle needle injectors for Kraft fürinspntzung with a combustion chamber, and arranged with an injector body, with the closing member or the nozzle needle drivingly coupled actuator directly.
  • Such a fuel injector is the subject of DE 10 2004 005 452 A1 ,
  • the actuator and a nozzle needle are arranged in mutually communicating high-pressure chambers and hydraulically coupled to each other where the hydraulic coupling space provided for this is separated from the actuator-side high-pressure chamber by a sealing sleeve which is arranged displaceably on a confirmed by the actuator master piston and by means supported on the piston suspension against the facing bottom of a guide body is stretched, which receives a plunger-like end of the nozzle needle slidably in an axial bore open towards the coupling space
  • the actuator must overcome considerable hydraulic forces when closing the nozzle needle, in addition to the transmission ratio of the hydraulic coupling wipe actuator and nozzle needle for take into account. Since the hydraulic coupling is selected such that small Aktorhübe lead to comparatively large strokes of the nozzle needle, so the actuator must apply a force during the closing stroke, which is higher by a multiple than the force acting on the nozzle needle hydraulic opening force.
  • a fuel injector is described, the nozzle needle is acted upon in its open position, that is, during the injection phase over its entire cross section of the high pressure of the injectors supplied fuel.
  • the DE 10 2004 005 452 A1 is in the embodiment of Figs. 5 and 6 of WO 2004/031551 A2 only a two-stage injection phase provided.
  • the nozzle needle initially lifts with an annular sealing surface (106) which is formed as an annular step on the nozzle needle, from an annular seating surface in the nozzle body and releases a pilot nozzle (112), can be injected via the fuel in the direction of a glow plug.
  • the nozzle needle with a plunger-like end which is arranged concentrically to the aforementioned annular sealing surface emerges from a bore arranged in the injector body, so that main injection nozzles (120) release and are supplied with the fuel supplied at high pressure.
  • main injection nozzles (120) release and are supplied with the fuel supplied at high pressure.
  • the object of the invention is now to show a particularly advantageous construction for a fuel injector with pressure-balanced arranged nozzle needle.
  • the invention is based on the general idea of constantly applying a partial cross-section of the nozzle needle to the pressure in the combustion chamber in the opening direction which is lower than the injection pressure of the fuel, so that the fluidic forces acting in the opening direction remain correspondingly low.
  • the nozzle needle can cooperate with high precision with their seat, so that a particularly accurate and reproducible opening and closing behavior can be ensured.
  • the closure member or the nozzle needle cooperate with an annular rim or zone concentric with the extension, with a seat annularly surrounding the injector inlets so that the injectors are shut off when the annular edge or zone is seated on the seat.
  • the annular surface which extends radially between the outer circumference of the plunger-like axial extension of the nozzle needle and the aforementioned annular edge or - zone, at the transition between closed and open position of the nozzle needle alternately from the pressure in the combustion chamber and the high pressure in the high pressure chamber Opening direction of the nozzle needle acted upon. Since the said annular surface can remain very small due to the regularly very small cross sections of the injection nozzles, the absolute difference between the effective in the closed position and in open position fluidic forces in the opening direction of the nozzle needle remains low. This makes it possible to achieve a good operating behavior of the actuator.
  • the fuel injector shown there has an injector body 1, which is segmented into a low-pressure body 2, an intermediate body 3 and a nozzle body 4, wherein the body 2-4 are axially braced against each other by a sleeve-shaped union nut 5.
  • the low-pressure body 2 encloses a low-pressure chamber 6, which communicates via a preferably throttled connecting line with a relatively pressureless fuel reservoir 7, for example a fuel tank.
  • the nozzle body 4 encloses a high pressure chamber 8, which is connected via a the intermediate body 3 and the low pressure body 2 passing through the supply line 9 with a high pressure source CR for fuel.
  • This high-pressure source CR can be designed as a so-called common rail.
  • the high pressure chamber 8 comprises two subspaces 8 'and 8 ", which are connected to one another axially via a bore 11 accommodating a nozzle needle 10 and a bore 12 parallel to the bore 11.
  • the bore 11 essentially serves to guide the nozzle needle 10 in an axially displaceable manner the upper end is guided in the intermediate body 3 in a bore 13 which is equiaxial to the bore 11.
  • the nozzle needle 10 has a step-shaped lower end such that a plunger-like axial projection 10 'is formed which fits into a matching guide bore in the lower end of the nozzle body 4 is guided axially displaceable.
  • This guide bore 14 is connected via a same axially continuing relief bore 140 constantly with a combustion chamber, not shown, of an internal combustion engine, wherein the below the front end of the extension 10 'remaining region of the guide bore 14 relative to the subspace 8 "of the high-pressure chamber by the immersed in the guide bore 14 extension 10 'is shut off.
  • annular seat is formed, which surrounds the inputs of star-shaped to the guide bore 14 injectors 15 annularly and with the formed on the stepped end portion of the nozzle needle 10 annular edge 10" sealingly cooperates, if the nozzle needle 10 in Fig. 1 shown closed position occupies.
  • a nozzle chamber 10 surrounding annular space 16 is arranged, which communicates with the low-pressure chamber 6. Accordingly, there is always low pressure in the annular space 16, and an optionally in the annular space between the outer periphery of the nozzle needle 10 and the inner circumference of the bore 13 penetrating leakage flow from the high pressure chamber 8 is passed into the low pressure chamber 6 and accordingly from the interior of the bore 13 above the upper end the nozzle needle 10 kept away.
  • the low-pressure space 6 in the low-pressure body 2 has an upper portion with a smaller diameter and a lower portion with an enlarged diameter.
  • the upper portion receives an example piezoelectric actuator 17 which is supported with a arranged at its upper end foot on a bottom of the low-pressure body 2 and with a at its in Fig. 1 arranged lower end piston 18 projects into the lower portion of the low-pressure chamber 6.
  • a sealing sleeve 19 is guided axially displaceable, which is clamped by means of a clamped between a collar on the piston 18 and a collar on the sealing sleeve 19 axially pressurized Bourdon tube 20 against the facing end face of the intermediate body 3, such that of the sealing sleeve 19 axially between the lower end face of the piston 18 and the facing end face of the intermediate body 3, a coupler space 21 is separated from the low pressure chamber 6.
  • This coupler space 21 communicates via an axial bore 22, preferably designed as a throttle bore, in the intermediate body 3
  • the coupler space 21 receives fluid from the bore 13 and the nozzle needle 10 performs an upstroke.
  • a stroke translation occurs, which is predetermined by the ratio of the cross sections of the piston 18 in the coupler space 21 and the nozzle needle 10 in the bore 13.
  • the annular sealing gap between the inner circumference of the sealing sleeve 19 and the outer periphery of the piston 18 is formed as a capillary, so that the coupler chamber 21 and the low-pressure chamber 6 are strongly throttled connected to each other.
  • the fuel injector shown in Fig. 1 functions as follows:
  • the piezoelectric actuator 17 When the piezoelectric actuator 17 is connected via the electrical connection lines 24 to an electrical voltage source and is charged accordingly, it assumes its vertically elongated state in which the piston 18 is brought from the actuator 17 in the illustrated lower dead center position and held in this position becomes. At the same time, the nozzle needle 10 assumes the closed position shown, in which it is held by its closing spring 23, wherein optionally fluid from the low pressure chamber 6 via the capillary gap between the sealing sleeve 19 and piston 18 seeps into the coupler chamber 21.
  • the actuator 17 As soon as the actuator 17 is decoupled from the aforementioned electrical voltage source and discharged, it goes into its vertically shortened state, wherein the piston 18 shifts to its upper end position. Since the coupler space 21 absorbs fluid from the bore 13 above the nozzle needle 10 during the upward stroke of the piston 18, the nozzle needle 10 is released from its Seat is excavated, wherein the input side of the injection nozzles 15 is connected to the lower subspace 8 "of the high-pressure chamber 8 and accordingly fuel is injected from the high-pressure chamber 8 in the connected combustion chamber.At the same time present in the high-pressure chamber 8 high pressure now acts on the annular surface between the outer periphery of the plunger-like Extension 10 'and the annular edge 10 "of the nozzle needle 10 in the upward direction.
  • the nozzle needle 10 is brought against the force of its closing spring 23 securely in their lifted from the seat open position and held, the exact position of the open position through the annular step at the transition of the bore 13 to the axial bore 22 can be given like a stop.
  • the actuator 17 requires only a small amount of power, because essentially only the high pressure must be overcome during the closing stroke of the nozzle needle 10, which acts on the annular surface between the annular edge 10 "and the plunger-like extension 10 'of the nozzle needle 10.
  • the said annular surface can have a very small surface area corresponding to the small cross section of the inlet side of the injection nozzles 15, the difference in the opening direction of the fluid needle in the opening direction remains very small. This results in that the actuating forces generated by the actuator 17 can remain low, so that a small and inexpensive actuator 17 is sufficient.
  • the relief hole As a throttle bore, a certain damping of the strokes of the nozzle needle 10 can be achieved.
  • the embodiment of the Fig. 2 differs from the embodiment of the Fig. 1 essentially only in that the actuator 17 and the nozzle needle 10 with each other "normal" are coupled, that is, the nozzle needle 10 assumes its closed position when the actuator 17 is electrically discharged and has its vertically shortened state, while the nozzle needle 10 passes into its open position when the actuator 17 is connected via the lines 24 to an electrical voltage source and is electrically charged, wherein the actuator 17 merges into its elongated state.
  • a sleeve 25, closed at its upper end by a bottom, is arranged, the interior of which through the upper part of a stepped piston 26 into an upper chamber 27, which via a radial opening in the sleeve 25 constantly is connected to the low pressure chamber 6, and an annular lower chamber 28 is divided, which communicates via a sleeve 25 axially passing through, preferably throttled channel 29 with the coupler chamber 21.
  • the lower part of the stepped piston 26 has in the illustrated example the same cross-section as the upper portion of the nozzle needle 10 in the bore 13, which merges to form a step in a lower part of the stepped piston 26 slidably receiving bore 30. Said step interacts with the lower end face of the lower part of the stepped piston 26 in a stop-like manner, such that the lower annular end face of the upper part of the stepped piston 26 always remains at a distance from the facing end face of the intermediate body 3.
  • the fuel injector of Fig. 2 functions as follows:
  • the stepped piston 26 could also be formed as part of the nozzle needle 10 or coaxially arranged to the nozzle needle 10. None changes at the function described above.

Description

Die Erfindung bezieht sich auf einen Kraftstoffinjektor mit in einem Injektorkörper angeordneten Hochdruckraum, welcher an eine Hochdruckquelle für Kraftstoff anschließbar und über von einem Schheßghed bzw. einer Dusennadel gesteuerte Einspritzdüsen zur Kraftstoffeinspntzung mit einem Brennraum verbindbar ist, und mit einem im Injektorkörper angeordneten, mit dem Schließglied bzw. der Düsennadel antriebsmäßig direkt gekoppelten Aktor.The invention relates to a fuel injector with arranged in an injector high-pressure chamber, which is connectable to a high pressure fuel source and controlled by a Schheßghed or a nozzle needle injectors for Kraftstoffeinspntzung with a combustion chamber, and arranged with an injector body, with the closing member or the nozzle needle drivingly coupled actuator directly.

Stand der TechnikState of the art

Ein derartiger Kraftstoffinjektor ist Gegenstand der DE 10 2004 005 452 A1 . Nach dieser Druckschrift sind der Aktor und eine Düsennadel in miteinander kommunizierenden Hochdruckräumen angeordnet und miteinander hydraulisch gekoppelt wobei der hiefür vorgesehene hydraulische Kopplungsraum vom aktorseitigen Hochdruckraum durch eine Dichthulse abgetrennt wird, die auf einem vom Aktor bestätigten Geberkolben verschiebbar angeordnet und mittels am Kolben abgestützter Federung gegen den zugewandten Boden eines Führungskörpers gespannt wird, der ein plungerartiges Ende der Düsennadel in einer zum Kopplungsraum hin offenen Axialbohrung verschiebbar aufnimmtSuch a fuel injector is the subject of DE 10 2004 005 452 A1 , According to this document, the actuator and a nozzle needle are arranged in mutually communicating high-pressure chambers and hydraulically coupled to each other where the hydraulic coupling space provided for this is separated from the actuator-side high-pressure chamber by a sealing sleeve which is arranged displaceably on a confirmed by the actuator master piston and by means supported on the piston suspension against the facing bottom of a guide body is stretched, which receives a plunger-like end of the nozzle needle slidably in an axial bore open towards the coupling space

Sobald die Düsennadel ihre die Einspritzdüsen freigebende Offenlage einnimmt, wird die Düsennadel auf ihrem gesamten Querschnitt von dem im düsennadelseitigen Hochdruckraum vorliegenden Hochdruck in Öffnungsrichtung beaufschlagt. Dementsprechend muss der Aktor beim Schließen der Düsennadel erhebliche hydraulische Kräfte überwinden, wobei zusätzlich das Übersetzungsverhältnis der hydraulischen Kopplung wischen Aktor und Düsennadel zur berücksichtigen ist. Da die hydraulische Kopplung derart ausgewählt ist, dass kleine Aktorhübe zu vergleichsweise großen Hüben der Düsennadel führen, muss also der Aktor beim Schließhub eine Kraft aufbringen, die um ein Vielfaches höher als die auf die Düsennadel wirkende hydraulische Öffnungskraft ist.As soon as the nozzle needle assumes its open position releasing the injection nozzles, the nozzle needle is acted upon in the opening direction over its entire cross section by the high pressure present in the nozzle needle-side high-pressure chamber. Accordingly, the actuator must overcome considerable hydraulic forces when closing the nozzle needle, in addition to the transmission ratio of the hydraulic coupling wipe actuator and nozzle needle for take into account. Since the hydraulic coupling is selected such that small Aktorhübe lead to comparatively large strokes of the nozzle needle, so the actuator must apply a force during the closing stroke, which is higher by a multiple than the force acting on the nozzle needle hydraulic opening force.

In der DE 43 06 073 C1 wird eine als Kraftstoffinjektor einsetzbare Zumessvorrichtung für Fluide dargestellt, wobei eine prinzipiell ähnliche Konstruktion wie in der vorgenannten Druckschrift vorgesehen ist. Abweichend davon ist im Wesentlichen nur vorgesehen, eine inverse hydraulische Kopplung zwischen Aktor und Düsennadel vorzusehen, das heißt eine Elongation des Aktors führt zu einem Düsennadelhub in Öffnungsrichtung, während gemäß der DE 10 2004 005 452 A1 eine normale hydraulische Kopplung zwischen Aktor und Düsennadel vorgesehen ist und ein Elongation des Aktors den Schließhub der Düsennadel bewirkt.In the DE 43 06 073 C1 a metering device for fluids which can be used as a fuel injector is shown, wherein a construction which is similar in principle to that in the aforementioned publication is provided. Deviating from this is essentially only provided to provide an inverse hydraulic coupling between the actuator and the nozzle needle, that is, an elongation of the actuator leads to a Düsennadelhub in the opening direction, while according to the DE 10 2004 005 452 A1 a normal hydraulic coupling between the actuator and the nozzle needle is provided and an elongation of the actuator causes the closing stroke of the nozzle needle.

In der WO 2004/031551 A2 wird wiederum ein Kraftstoffinjektor beschrieben, dessen Düsennadel in ihrer Offenstellung, d.h. während der Einspritzphase auf ihrem gesamten Querschnitt vom Hochdruck des den Einspritzdüsen zugeführten Kraftstoffes beaufschlagt wird. Im Unterschied zum Kraftstoffinjektor der DE 10 2004 005 452 A1 ist bei der Ausführungsform der Fig. 5 und 6 der WO 2004/031551 A2 lediglich eine zweistufige Einspritzphase vorgesehen. Beim Öffnungshub hebt die Düsennadel zunächst mit einer ringförmigen Dichtfläche (106) die als Ringstufe an der Düsennadel ausgebildet ist, von einer ringförmigen Sitzfläche im Düsenkörper ab und gibt eine Pilotdüse (112) frei, über die Kraftstoff in Richtung einer Glühkerze gespritzt werden kann. Beim weiteren Öffnungshub tritt die Düsennadel mit einem plungerartigen Ende, welches konzentrisch zur vorgenannten ringförmigen Dichtfläche angeordnet ist, aus einer im Injektorkörper angeordneten Bohrung aus, so dass Haupteinspritzdüsen (120) freigeben und mit dem unter Hochdruck zugeführten Kraftstoff beliefert werden. Nunmehr wird also der gesamte Querschnitt der Düsennadel von dem unter Hochdruck stehenden Kraftstoff in Öffnungsrichtung beaufschlagt. Dementsprechend muss der Aktor beim nachfolgenden Schließhub große Schließkräfte erzeugern können.In the WO 2004/031551 A2 In turn, a fuel injector is described, the nozzle needle is acted upon in its open position, that is, during the injection phase over its entire cross section of the high pressure of the injectors supplied fuel. Unlike the fuel injector the DE 10 2004 005 452 A1 is in the embodiment of Figs. 5 and 6 of WO 2004/031551 A2 only a two-stage injection phase provided. During the opening stroke, the nozzle needle initially lifts with an annular sealing surface (106) which is formed as an annular step on the nozzle needle, from an annular seating surface in the nozzle body and releases a pilot nozzle (112), can be injected via the fuel in the direction of a glow plug. During the further opening stroke, the nozzle needle with a plunger-like end which is arranged concentrically to the aforementioned annular sealing surface emerges from a bore arranged in the injector body, so that main injection nozzles (120) release and are supplied with the fuel supplied at high pressure. Now, therefore, the entire cross section of the nozzle needle is acted upon by the fuel under high pressure in the opening direction. Accordingly, the actuator must be able to produce large closing forces during the subsequent closing stroke.

Offenbarung der ErfindungDisclosure of the invention

Grundsätzlich ist es erwilnscht, den Kraftstoffinjektor konstruktiv derart auszugestalten, dass der Leistungsbedarf des Aktors beim Öffnungs- bzw. Schließhub der Düsennadel gering bleibt. Dazu ist Voraussetzung, dass in der jeweiligen Hubrichtung der Düsennadel nur geringe hydraulische oder sonstige Widerstände bzw. Rückstellkräfte überwunden werden müssen.Basically, it is desirable to structurally design the fuel injector such that the power requirement of the actuator remains small during the opening or closing stroke of the nozzle needle. This requires that only slight hydraulic or other resistances or restoring forces have to be overcome in the respective stroke direction of the nozzle needle.

In diesem Zusammenhang wird eine druckausgeglichene Anordnung der Düsennadel angestrebt.In this context, a pressure-balanced arrangement of the nozzle needle is desired.

Aufgabe der Erfindung ist es nun, für einen Kraftstoffinjektor mit druckausgeglichen angeordneter Düsennadel eine besonders vorteilhafte Konstruktion aufzuzeigen.The object of the invention is now to show a particularly advantageous construction for a fuel injector with pressure-balanced arranged nozzle needle.

Diese Aufgabe wird erfindungsgemäß durch die kennzeichnenden Merkmale des Anspruches 1 gelöst.This object is achieved by the characterizing features of claim 1.

Die Erfindung beruht auf dem allgemeinen Gedanken, einen Teilquerschnitt der Düsennadel ständig mit dem gegenüber dem Einspritzdruck des Kraftstoffes größenordnungsmäßig geringeren Druck im Brennraum in Öffnungsrichtung zu beaufschlagen, so dass die in Öffnungsrichtung wirkenden fluidischen Kräfte entsprechend gering bleiben.The invention is based on the general idea of constantly applying a partial cross-section of the nozzle needle to the pressure in the combustion chamber in the opening direction which is lower than the injection pressure of the fuel, so that the fluidic forces acting in the opening direction remain correspondingly low.

Da die Führungsbohrung im Zusammenwirken mit dem plungerartigen axialen Fortsatz der Düsennadel eine exakte axiale Führung der Düsennadel an den Einspritzdüsen bewirkt, kann die Düsennadel mit hoher Präzision mit ihrem Sitz zusammenwirken, so dass ein besonders exaktes und reproduzierbares Öffnungs- und Schließverhalten gewährleistet werden.Since the guide bore in cooperation with the plunger-like axial extension of the nozzle needle causes an exact axial guidance of the nozzle needle to the injectors, the nozzle needle can cooperate with high precision with their seat, so that a particularly accurate and reproducible opening and closing behavior can be ensured.

In konstruktiv bevorzugter Weise wirken das Schließglied bzw. die Düsennadel mit einer zum Fortsatz konzentrischen Ringkante bzw. -zone mit einem die Eingänge der Einspritzdüsen ringförmig umschließenden Sitz zusammen, so dass die Einspritzdüsen bei auf dem Sitz aufsitzender Ringkante bzw. -zone abgesperrt sind.In a structurally preferred manner, the closure member or the nozzle needle cooperate with an annular rim or zone concentric with the extension, with a seat annularly surrounding the injector inlets so that the injectors are shut off when the annular edge or zone is seated on the seat.

Bei dieser Ausführungsform wird die Ringfläche, welche sich radial zwischen dem Außenumfang des plungerartigen axialen Fortsatzes der Düsennadel und der vorgenannten Ringkante bzw. - zone erstreckt, beim Übergang zwischen Schließ- und Offenlage der Düsennadel abwechselnd vom Druck im Brennraum bzw. vom Hochdruck im Hochdruckraum in Öffnungsrichtung der Düsennadel beaufschlagt. Da die genannte Ringfläche aufgrund der regelmäßig sehr geringen Querschnitte der Einspritzdüsen sehr klein bleiben kann, bleibt die Absolutdifferenz zwischen den in Schließlage bzw. in Offenlage wirksamen fluidischen Kräfte in Öffnungsrichtung der Düsennadel gering. Damit lässt sich ein gutes Betriebsverhalten des Aktors erreichen.In this embodiment, the annular surface, which extends radially between the outer circumference of the plunger-like axial extension of the nozzle needle and the aforementioned annular edge or - zone, at the transition between closed and open position of the nozzle needle alternately from the pressure in the combustion chamber and the high pressure in the high pressure chamber Opening direction of the nozzle needle acted upon. Since the said annular surface can remain very small due to the regularly very small cross sections of the injection nozzles, the absolute difference between the effective in the closed position and in open position fluidic forces in the opening direction of the nozzle needle remains low. This makes it possible to achieve a good operating behavior of the actuator.

Im übrigen wird hinsichtlich bevorzugter Merkmale der Erfindung auf die Ansprüche und die nachfolgende Erläuterung der Zeichnung verwiesen, anhand der besonders bevorzugte Ausführungsformen der Erfindung näher beschrieben werden.Moreover, reference is made to the claims and the following explanation of the drawing with regard to preferred features of the invention, are described in detail with reference to the particularly preferred embodiments of the invention.

Kurze Beschreibung der ZeichnungShort description of the drawing

In der Zeichnung zeigt:

Fig. 1
einen Axialschnitt eines erfindungsgemäßen Kraftstoffinjektors gemäß einer ersten Ausführungsform mit inverser hydraulischer Kopplung zwischen Aktor und Düsennadel, das heißt die Düsennadel schließt bei Elongation des Aktors, und
Fig. 2
einen Axialschnitt eines erfindungsgemäßen Kraftstoffinjektors mit normaler hydraulischer Kopplung zwischen Aktor und Düsennadel.
In the drawing shows:
Fig. 1
an axial section of a fuel injector according to the invention according to a first embodiment with inverse hydraulic coupling between the actuator and the nozzle needle, that is, the nozzle needle closes upon elongation of the actuator, and
Fig. 2
an axial section of a fuel injector according to the invention with normal hydraulic coupling between the actuator and the nozzle needle.

Ausführungsformen der ErfindungEmbodiments of the invention

Gemäß Fig. 1 besitzt der dort dargestellte Kraftstoffinjektor einen Injektorkörper 1, der in einen Niederdruckkörper 2, einen Zwischenkörper 3 sowie einen Düsenkörper 4 segmentiert ist, wobei die Körper 2-4 durch eine hülsenförmige Überwurfmutter 5 gegeneinander axial verspannt werden.According to Fig. 1 the fuel injector shown there has an injector body 1, which is segmented into a low-pressure body 2, an intermediate body 3 and a nozzle body 4, wherein the body 2-4 are axially braced against each other by a sleeve-shaped union nut 5.

Der Niederdruckkörper 2 umschließt einen Niederdruckraum 6, der über eine vorzugsweise gedrosselte Verbindungsleitung mit einem relativ drucklosen Kraftstoffreservoir 7, beispielsweise ein Kraftstofftank, kommuniziert. Der Düsenkörper 4 umschließt einen Hochdruckraum 8, der über eine den Zwischenkörper 3 sowie den Niederdruckkörper 2 durchsetzende Versorgungsleitung 9 mit einer Hochdruckquelle CR für Kraftstoff verbunden ist. Diese Hochdruckquelle CR kann als sogenanntes Common Rail ausgebildet sein.The low-pressure body 2 encloses a low-pressure chamber 6, which communicates via a preferably throttled connecting line with a relatively pressureless fuel reservoir 7, for example a fuel tank. The nozzle body 4 encloses a high pressure chamber 8, which is connected via a the intermediate body 3 and the low pressure body 2 passing through the supply line 9 with a high pressure source CR for fuel. This high-pressure source CR can be designed as a so-called common rail.

Der Hochdruckraum 8 umfasst zwei Teilräume 8' und 8", die miteinander axial über eine eine Düsennadel 10 verschiebbar aufnehmende Bohrung 11 sowie eine dazu parallele Bohrung 12 verbunden sind. Die Bohrung 11 dient im Wesentlichen zur axial verschiebbaren Führung der Düsennadel 10, die an ihrem oberen Ende in einer zur Bohrung 11 gleichachsigen Bohrung 13 im Zwischenkörper 3 geführt ist. Die Düsennadel 10 besitzt ein stufenförmig ausgebildetes unteres Ende, derart, dass ein plungerartiger axialer Fortsatz 10' gebildet wird, welcher in einer dazu passenden Führungsbohrung im unteren Ende des Düsenkörpers 4 axial verschiebbar geführt ist.The high pressure chamber 8 comprises two subspaces 8 'and 8 ", which are connected to one another axially via a bore 11 accommodating a nozzle needle 10 and a bore 12 parallel to the bore 11. The bore 11 essentially serves to guide the nozzle needle 10 in an axially displaceable manner the upper end is guided in the intermediate body 3 in a bore 13 which is equiaxial to the bore 11. The nozzle needle 10 has a step-shaped lower end such that a plunger-like axial projection 10 'is formed which fits into a matching guide bore in the lower end of the nozzle body 4 is guided axially displaceable.

Diese Führungsbohrung 14 ist über eine dieselbe axial fortsetzende Entlastungsbohrung 140 ständig mit einem nicht dargestellten Brennraum eines Verbrennungsmotors verbunden, wobei der unterhalb des Stirnendes des Fortsatzes 10' verbleibende Bereich der Führungsbohrung 14 gegenüber dem Teilraum 8" des Hochdruckraumes durch den in die Führungsbohrung 14 eintauchenden Fortsatz 10' abgesperrt wird.This guide bore 14 is connected via a same axially continuing relief bore 140 constantly with a combustion chamber, not shown, of an internal combustion engine, wherein the below the front end of the extension 10 'remaining region of the guide bore 14 relative to the subspace 8 "of the high-pressure chamber by the immersed in the guide bore 14 extension 10 'is shut off.

Am Übergangsbereich zwischen der Führungsbohrung 14 und dem Teilraum 8" des Hochdruckraumes 8 ist ein ringförmiger Sitz ausgebildet, der die Eingänge von sternförmig zur Führungsbohrung 14 angeordneten Einspritzdüsen 15 ringförmig umschließt und mit der am stufenförmigen Endbereich der Düsennadel 10 ausgebildeten Ringkante 10" dichtend zusammenwirkt, wenn die Düsennadel 10 die in Fig. 1 dargestellte Schließlage einnimmt.At the transition region between the guide bore 14 and the subspace 8 "of the high-pressure chamber 8, an annular seat is formed, which surrounds the inputs of star-shaped to the guide bore 14 injectors 15 annularly and with the formed on the stepped end portion of the nozzle needle 10 annular edge 10" sealingly cooperates, if the nozzle needle 10 in Fig. 1 shown closed position occupies.

Innerhalb des Zwischenkörpers 3 ist ein die Düsennadel 10 umschließender Ringraum 16 angeordnet, welcher mit dem Niederdruckraum 6 kommuniziert. Dementsprechend liegt im Ringraum 16 immer Niederdruck vor, und ein gegebenenfalls in den Ringraum zwischen dem Außenumfang der Düsennadel 10 und dem Innenumfang der Bohrung 13 eindringender Leckagestrom aus dem Hochdruckraum 8 wird in den Niederdruckraum 6 geleitet und dementsprechend vom Innenraum der Bohrung 13 oberhalb des oberen Endes der Düsennadel 10 ferngehalten.Within the intermediate body 3, a nozzle chamber 10 surrounding annular space 16 is arranged, which communicates with the low-pressure chamber 6. Accordingly, there is always low pressure in the annular space 16, and an optionally in the annular space between the outer periphery of the nozzle needle 10 and the inner circumference of the bore 13 penetrating leakage flow from the high pressure chamber 8 is passed into the low pressure chamber 6 and accordingly from the interior of the bore 13 above the upper end the nozzle needle 10 kept away.

Der Niederdruckraum 6 im Niederdruckkörper 2 besitzt einen oberen Abschnitt mit kleinerem Durchmesser und einem unteren Abschnitt mit vergrößertem Durchmesser. Der obere Abschnitt nimmt einen beispielsweise piezoelektrischen Aktor 17 auf, der mit einem an seinem oberen Ende angeordneten Fuß auf einem Boden des Niederdruckkörpers 2 abgestützt ist und mit einem an seinem in Fig. 1 unteren Ende angeordneten Kolben 18 in den unteren Abschnitt des Niederdruckraumes 6 hineinragt. Auf dem Kolben 18 ist eine Dichthülse 19 axial verschiebbar geführt, die mittels einer zwischen einem Kragen am Kolben 18 und einem Kragen an der Dichthülse 19 axial auf Druck eingespannten Rohrfeder 20 gegen die zugewandte Stirnseite des Zwischenkörpers 3 gespannt wird, derart, dass von der Dichthülse 19 axial zwischen der unteren Stirnseite des Kolbens 18 und der zugewandten Stirnseite des Zwischenkörpers 3 ein Kopplerraum 21 vom Niederdruckraum 6 abgetrennt wird. Dieser Kopplerraum 21 kommuniziert über eine vorzugsweise als Drosselbohrung ausgebildete Axialbohrung 22 im Zwischenkörper 3 mit dem Innenraum der im Zwischenkörper 3 angeordneten Bohrung 13 bzw. mit dem Abschnitt dieser Bohrung 13 oberhalb des oberen Endes der Düsennadel 10. Wenn der Kolben 18 einen Abwärtshub ausführt, wird Fluid aus dem Kopplerraum 21 in die Bohrung 13 verdrängt, so dass die Düsennadel 10 nach abwärts verschoben wird. Wenn der Kolben 18 einen Aufwärtshub ausführt, nimmt der Kopplerraum 21 Fluid aus der Bohrung 13 auf und die Düsennadel 10 führt einen Aufwärtshub aus. Dabei tritt eine Hubübersetzung auf, die durch das Verhältnis der Querschnitte des Kolbens 18 im Kopplerraum 21 und der Düsennadel 10 in der Bohrung 13 vorgegeben ist.The low-pressure space 6 in the low-pressure body 2 has an upper portion with a smaller diameter and a lower portion with an enlarged diameter. The upper portion receives an example piezoelectric actuator 17 which is supported with a arranged at its upper end foot on a bottom of the low-pressure body 2 and with a at its in Fig. 1 arranged lower end piston 18 projects into the lower portion of the low-pressure chamber 6. On the piston 18, a sealing sleeve 19 is guided axially displaceable, which is clamped by means of a clamped between a collar on the piston 18 and a collar on the sealing sleeve 19 axially pressurized Bourdon tube 20 against the facing end face of the intermediate body 3, such that of the sealing sleeve 19 axially between the lower end face of the piston 18 and the facing end face of the intermediate body 3, a coupler space 21 is separated from the low pressure chamber 6. This coupler space 21 communicates via an axial bore 22, preferably designed as a throttle bore, in the intermediate body 3 When the piston 18 performs a downward stroke, fluid is displaced from the coupler chamber 21 into the bore 13, so that the nozzle needle 10 is moved downwards. When the piston 18 performs an upstroke, the coupler space 21 receives fluid from the bore 13 and the nozzle needle 10 performs an upstroke. In this case, a stroke translation occurs, which is predetermined by the ratio of the cross sections of the piston 18 in the coupler space 21 and the nozzle needle 10 in the bore 13.

Der ringförmige Dichtspalt zwischen dem Innenumfang der Dichthülse 19 und dem Außenumfang des Kolbens 18 ist als Kapillarspalt ausgebildet, so dass der Kopplerraum 21 und der Niederdruckraum 6 stark gedrosselt miteinander verbunden sind.The annular sealing gap between the inner circumference of the sealing sleeve 19 and the outer periphery of the piston 18 is formed as a capillary, so that the coupler chamber 21 and the low-pressure chamber 6 are strongly throttled connected to each other.

Damit wird im Betrieb des Kraftstoffinjektors gewährleistet, dass der Kopplerraum 21 und der damit verbundene Teilraum der Bohrung 13 oberhalb der Düsennadel 10 eine genau passende Fluidmenge aufnehmen, wenn die Düsennadel 10 die dargestellte Schließlage und der Kolben 18 die dargestellte untere Totpunktlage einnehmen.This ensures during operation of the fuel injector that the coupler chamber 21 and the associated subspace of the bore 13 above the nozzle needle 10 record a precisely fitting amount of fluid when the nozzle needle 10 occupy the illustrated closed position and the piston 18 shown bottom dead center.

Der in Fig. 1 dargestellte Kraftstoffinjektor funktioniert wie folgt:The fuel injector shown in Fig. 1 functions as follows:

Wenn der piezoelektrische Aktor 17 über die elektrischen Anschlussleitungen 24 mit einer elektrischen Spannungsquelle verbunden wird und dementsprechend elektrisch aufgeladen wird, nimmt er seinen vertikal elongierten Zustand ein, bei dem der Kolben 18 vom Aktor 17 in die zeichnerisch dargestellte untere Totpunktlage gebracht und in dieser Lage gehalten wird. Gleichzeitig nimmt die Düsennadel 10 die dargestellte Schließlage ein, in der sie von ihrer Schließfeder 23 gehalten wird, wobei gegebenenfalls Fluid aus dem Niederdruckraum 6 über den Kapillarspalt zwischen Dichthülse 19 und Kolben 18 in den Kopplerraum 21 einsickert.When the piezoelectric actuator 17 is connected via the electrical connection lines 24 to an electrical voltage source and is charged accordingly, it assumes its vertically elongated state in which the piston 18 is brought from the actuator 17 in the illustrated lower dead center position and held in this position becomes. At the same time, the nozzle needle 10 assumes the closed position shown, in which it is held by its closing spring 23, wherein optionally fluid from the low pressure chamber 6 via the capillary gap between the sealing sleeve 19 and piston 18 seeps into the coupler chamber 21.

Sobald der Aktor 17 von der vorgenannten elektrischen Spannungsquelle abgekoppelt und entladen wird, geht er in seinen vertikal verkürzten Zustand über, wobei sich der Kolben 18 in seine obere Endlage verschiebt. Da der Kopplerraum 21 beim Aufwärtshub des Kolbens 18 Fluid aus der Bohrung 13 oberhalb der Düsennadel 10 aufnimmt, wird die Düsennadel 10 aus ihrem Sitz ausgehoben, wobei die Eingangsseite der Einspritzdüsen 15 mit dem unteren Teilraum 8" des Hochdruckraumes 8 verbunden wird und dementsprechend Kraftstoff aus dem Hochdruckraum 8 in den angeschlossenen Brennraum eingespritzt wird. Gleichzeitig beaufschlagt der im Hochdruckraum 8 vorliegende Hochdruck nunmehr die Ringfläche zwischen dem Außenumfang des plungerartigen Fortsatzes 10' und der Ringkante 10" der Düsennadel 10 in Aufwärtsrichtung. Damit wird einerseits die Düsennadel 10 gegen die Kraft ihrer Schließfeder 23 sicher in ihre vom Sitz abgehobene Offenlage gebracht und gehalten, wobei die exakte Position der Offenlage durch die Ringstufe am Übergang der Bohrung 13 zur Axialbohrung 22 anschlagartig vorgegeben werden kann.As soon as the actuator 17 is decoupled from the aforementioned electrical voltage source and discharged, it goes into its vertically shortened state, wherein the piston 18 shifts to its upper end position. Since the coupler space 21 absorbs fluid from the bore 13 above the nozzle needle 10 during the upward stroke of the piston 18, the nozzle needle 10 is released from its Seat is excavated, wherein the input side of the injection nozzles 15 is connected to the lower subspace 8 "of the high-pressure chamber 8 and accordingly fuel is injected from the high-pressure chamber 8 in the connected combustion chamber.At the same time present in the high-pressure chamber 8 high pressure now acts on the annular surface between the outer periphery of the plunger-like Extension 10 'and the annular edge 10 "of the nozzle needle 10 in the upward direction. Thus, on the one hand, the nozzle needle 10 is brought against the force of its closing spring 23 securely in their lifted from the seat open position and held, the exact position of the open position through the annular step at the transition of the bore 13 to the axial bore 22 can be given like a stop.

Für den nachfolgenden Schließhub der Düsennadel 10 benötigt der Aktor 17 nur eine geringe Leistung, weil beim Schließhub der Düsennadel 10 im Wesentlichen nur der Hochdruck überwunden werden muss, welcher die Ringfläche zwischen der Ringkante 10" und dem plungerartigen Fortsatz 10' der Düsennadel 10 beaufschlagt. Der über die Entlastungsbohrung 140 den Querschnitt des Fortsatzes 10' beaufschlagende Druck des Brennraums kann in diesem Zusammenhang vernachlässigt werden, weil der Brennraumdruck ganz erheblich niedriger als der Druck der Kraftstoff-Hochdruckquelle CR ist. Sobald die Düsennadel 10 wieder ihre Schließlage erreicht hat und die Ringkante 10" der Düsennadel 10 auf dem zugeordneten Sitz im Teilraum 8" des Hochdruckraumes 8 aufsitzt, wird der Eingangsbereich der Einspritzdüsen 15 gegenüber dem Hochdruckraum 8 abgesperrt und die Ringfläche zwischen der Ringkante 10" und dem plungerartigen Fortsatz 10' der Düsennadel 10 wird dementsprechend nur noch vom Druck im Brennraum beaufschlagt. Da die genannte Ringfläche entsprechend dem geringen Querschnitt der Eingangsseite der Einspritzdüsen 15 ein sehr kleines Flächenmaß aufweisen kann, bleibt die Differenz der auf die Düsennadel 10 in Offen- oder Schließlage wirkenden fluidischen Kräfte in Öffnungsrichtung sehr gering. Dies führt dazu, dass die vom Aktor 17 erzeugten Stellkräfte gering bleiben können, so dass ein kleiner und preisgünstiger Aktor 17 ausreicht.For the subsequent closing stroke of the nozzle needle 10, the actuator 17 requires only a small amount of power, because essentially only the high pressure must be overcome during the closing stroke of the nozzle needle 10, which acts on the annular surface between the annular edge 10 "and the plunger-like extension 10 'of the nozzle needle 10. The pressure of the combustion chamber acting on the relief bore 140 over the cross-section of the extension 10 'can be neglected in this context because the combustion chamber pressure is considerably lower than the pressure of the high-pressure fuel source CR Once the nozzle needle 10 has again reached its closed position and the annular edge 10 "of the nozzle needle 10 is seated on the associated seat in the subspace 8" of the high pressure chamber 8, the entrance area of the injectors 15 is shut off from the high pressure chamber 8 and the annular surface between the annular edge 10 "and the plunger-like extension 10 'of the nozzle needle 10 is accordingly only from the pressure in Combustion chamber acted upon. Since the said annular surface can have a very small surface area corresponding to the small cross section of the inlet side of the injection nozzles 15, the difference in the opening direction of the fluid needle in the opening direction remains very small. This results in that the actuating forces generated by the actuator 17 can remain low, so that a small and inexpensive actuator 17 is sufficient.

Durch Ausbildung der Entlastungsbohrung als Drosselbohrung kann eine gewisse Dämpfung der Hübe der Düsennadel 10 erreicht werden.By forming the relief hole as a throttle bore, a certain damping of the strokes of the nozzle needle 10 can be achieved.

Die Ausführungsform der Fig. 2 unterscheidet sich von der Ausführungsform der Fig. 1 im Wesentlichen nur dadurch, dass der Aktor 17 und die Düsennadel 10 miteinander "normal" gekoppelt sind, das heißt die Düsennadel 10 nimmt ihre Schließlage ein, wenn der Aktor 17 elektrisch entladen ist und seinen vertikal verkürzten Zustand aufweist, während die Düsennadel 10 in ihre Offenlage übergeht, wenn der Aktor 17 über die Leitungen 24 mit einer elektrischen Spannungsquelle verbunden und elektrisch aufgeladen wird, wobei der Aktor 17 in seinen elongierten Zustand übergeht. Um diese normale Kopplung zu gewährleisten, ist axial unterhalb des Kopplungsraumes 21 eine an ihrem oberen Ende durch einen Boden abgeschlossene Hülse 25 angeordnet, deren Innenraum durch den oberen Teil eines Stufenkolbens 26 in eine obere Kammer 27, welche über eine Radialöffnung in der Hülse 25 ständig mit dem Niederdruckraum 6 verbunden ist, und eine ringförmige untere Kammer 28 unterteilt wird, die über einen die Hülse 25 axial durchsetzenden, vorzugsweise gedrosselten Kanal 29 mit dem Kopplerraum 21 kommuniziert. Der untere Teil des Stufenkolbens 26 besitzt im dargestellten Beispiel gleichen Querschnitt wie der obere Bereich der Düsennadel 10 in der Bohrung 13, die unter Bildung einer Stufe in eine den unteren Teil des Stufenkolbens 26 verschiebbar aufnehmende Bohrung 30 übergeht. Die genannte Stufe wirkt mit der unteren Stirnfläche des unteren Teiles des Stufenkolbens 26 anschlagartig zusammen, derart, dass die untere ringförmige Stirnseite des oberen Teiles des Stufenkolbens 26 immer von der zugewandten Stirnseite des Zwischenkörpers 3 beabstandet bleibt.The embodiment of the Fig. 2 differs from the embodiment of the Fig. 1 essentially only in that the actuator 17 and the nozzle needle 10 with each other "normal" are coupled, that is, the nozzle needle 10 assumes its closed position when the actuator 17 is electrically discharged and has its vertically shortened state, while the nozzle needle 10 passes into its open position when the actuator 17 is connected via the lines 24 to an electrical voltage source and is electrically charged, wherein the actuator 17 merges into its elongated state. In order to ensure this normal coupling, axially below the coupling space 21, a sleeve 25, closed at its upper end by a bottom, is arranged, the interior of which through the upper part of a stepped piston 26 into an upper chamber 27, which via a radial opening in the sleeve 25 constantly is connected to the low pressure chamber 6, and an annular lower chamber 28 is divided, which communicates via a sleeve 25 axially passing through, preferably throttled channel 29 with the coupler chamber 21. The lower part of the stepped piston 26 has in the illustrated example the same cross-section as the upper portion of the nozzle needle 10 in the bore 13, which merges to form a step in a lower part of the stepped piston 26 slidably receiving bore 30. Said step interacts with the lower end face of the lower part of the stepped piston 26 in a stop-like manner, such that the lower annular end face of the upper part of the stepped piston 26 always remains at a distance from the facing end face of the intermediate body 3.

Mittels einer auf dem Boden der Hülse 25 abgestützten Schraubendruckfeder 31 wird der Stufenkolben 26 in Richtung der vorgenannten Stufe zwischen den Bohrungen 13 und 30 gespannt.By means of a supported on the bottom of the sleeve 25 helical compression spring 31 of the stepped piston 26 is tensioned in the direction of the aforementioned stage between the holes 13 and 30.

Der Kraftstoffinjektor der Fig. 2 funktioniert wie folgt:The fuel injector of Fig. 2 functions as follows:

Wenn der Aktor 17 elektrisch entladen ist und dementsprechend seinen vertikal kurzen Zustand hat, befinden sich alle Elemente des dargestellten Kraftstoffinjektors in den dargestellten Lagen. Wird nun der Aktor 17 über die Leitungen 24 mit einer elektrischen Spannungsquelle verbunden, wird der Aktor 17 elektrisch aufgeladen, so dass er in seinen elongierten Zustand übergeht. Damit wird der Kolben 18 nach abwärts verschoben, so dass Fluid aus dem Kopplerraum 21 über die axiale Bohrung 29 in der Hülse 25 in die untere Kammer 28 eingeschoben und der Stufenkolben 26 dementsprechend nach aufwärts verschoben wird. Dies hat zur Folge, dass die Düsennadel 10 ebenfalls nach aufwärts verschoben und in ihre Offenlage gebracht wird. Wenn nachfolgend der Aktor 17 durch elektrische Entladung wiederum in seinen kurzen Zustand gebracht wird, verschiebt sich der Kolben 18 in Aufwärtsrichtung, so dass der Kopplerraum 21 Medium aus dem Ringraum 28 aufnimmt und der Stufenkolben 26 in die zeichnerisch dargestellte Lage nach abwärts geschoben wird. Dies hat zur Folge, dass die Düsennadel 10 ihren Schließhub ausführt.When the actuator 17 is electrically discharged and accordingly has its vertically short state, all elements of the illustrated fuel injector are in the illustrated positions. If now the actuator 17 is connected via lines 24 to an electrical voltage source, the actuator 17 is electrically charged, so that it goes into its elongated state. Thus, the piston 18 is displaced downwards, so that fluid is pushed from the coupler chamber 21 via the axial bore 29 in the sleeve 25 in the lower chamber 28 and the stepped piston 26 is accordingly shifted upward. This has the consequence that the nozzle needle 10 is also displaced upwards and brought into its open position. If subsequently the Actuator 17 is again brought into its short state by electrical discharge, the piston 18 moves in the upward direction, so that the coupler chamber 21 receives medium from the annular space 28 and the stepped piston 26 is pushed in the position shown in the drawing downwards. This has the consequence that the nozzle needle 10 performs its closing stroke.

Abweichend von der zeichnerisch dargestellten Ausführungsform könnte der Stufenkolben 26 auch als Teil der Düsennadel 10 ausgebildet bzw. gleichachsig zur Düsennadel 10 angeordnet sein. An der vorangehend beschriebenen Funktion ändert sich dabei nichts.Notwithstanding the illustrated embodiment, the stepped piston 26 could also be formed as part of the nozzle needle 10 or coaxially arranged to the nozzle needle 10. Nothing changes at the function described above.

Claims (8)

  1. Fuel injector having
    - a high-pressure chamber (8) which is arranged in an injector body (1) and which can be connected to a high-pressure source (CR) for fuel and which can be connected to a combustion chamber, for the injection of fuel, by means of injection nozzles (15) that are controlled by a closing element or a nozzle needle (10), and
    - an actuator (17) which is arranged in the injector body (1) and which is coupled in terms of drive to the closing element or nozzle needle (10),
    characterized
    in that the closing element or nozzle needle (10), at its end adjacent to the injection nozzles (15), is guided in an axially displaceable manner by way of a plunger-like axial projection (10') in a guide bore (14) arranged on or in the injector body (1), the interior of which guide bore is, at one side, permanently separated from the high-pressure chamber (8) by the axial projection (10') and communicates, at the other side, with the combustion chamber via a relief bore (140) on or in the injector body (1), and in that the closing element or nozzle needle (10), by way of an annular edge (10") that is concentric with respect to the projection (10'), interacts with a seat annularly surrounding the inlets of the injection nozzles (15) and shuts off the injection nozzles (15) with respect to the high-pressure chamber (8) when seated on the seat in a closed position.
  2. Fuel injector according to Claim 1,
    characterized
    in that the guide bore (14) is in the form of a blind bore and is connected to the combustion chamber via the relief bore (140) arranged on the base of the blind bore.
  3. Fuel injector according to Claim 1 or 2,
    characterized
    in that the actuator (17) is arranged in a low-pressure chamber (6) that can be connected to a relatively unpressurized fuel reservoir (7).
  4. Fuel injector according to one of Claims 1 to 3,
    characterized
    in that the actuator (17) is hydraulically coupled to the closing element or nozzle needle (10).
  5. Fuel injector according to Claim 4,
    characterized
    in that the actuator (17) actuates a piston (18) which is arranged, as a transmitter with displacement body action, in a coupling chamber (21), and the closing element or nozzle needle (10) has an actuator-side end which is arranged, with displacement body action, in a space that communicates with or is coupled to the coupling chamber (21).
  6. Fuel injector according to either of Claims 4 and 5,
    characterized
    in that the actuator (17) and closing element or nozzle needle (10) are coupled inversely to one another, wherein the closing element or nozzle needle (10) assumes the open position when the actuator (17) is in its electrically discharged state.
  7. Fuel injector according to one of Claims 1 to 6,
    characterized
    in that the inlets of the injection nozzles (15) are arranged in an annular zone radially between an annular seat of the closing element or nozzle needle (10) and the guide bore (14) that communicates with the combustion chamber.
  8. Fuel injector according to Claim 1 or 2,
    characterized
    in that the relief bore (140) is in the form of a throttle bore for damping the strokes of the nozzle needle.
EP09169844.9A 2008-12-09 2009-09-09 Fuel injector Not-in-force EP2199590B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102008054425 2008-12-09
DE102009001131A DE102009001131A1 (en) 2008-12-09 2009-02-25 fuel injector

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EP2199590A1 EP2199590A1 (en) 2010-06-23
EP2199590B1 true EP2199590B1 (en) 2014-08-06

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP09169844.9A Not-in-force EP2199590B1 (en) 2008-12-09 2009-09-09 Fuel injector

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EP (1) EP2199590B1 (en)
DE (1) DE102009001131A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012219867A1 (en) 2012-10-30 2014-04-30 Robert Bosch Gmbh Fuel injector with piezo actuator

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4306073C1 (en) 1993-02-26 1994-06-01 Siemens Ag Metering system for dosing of fluids with injection valve for IC engine - has piston acting on closing unit, and spring with actuator acting on large dia. piston moving in cylinder
DE19943142A1 (en) * 1999-09-09 2001-04-12 Siemens Ag Direct fuel injection dosing/proportioning device especially for petrol and diesel-powered combustion engines
DE10051896A1 (en) * 2000-10-19 2002-05-02 Bosch Gmbh Robert Fuel injection valve for IC engines has valve closure body with integral guide journal acting with valve seat body aperture for axial guidance
CA2406137C (en) 2002-10-02 2004-12-28 Westport Research Inc. Control method and apparatus for gaseous fuelled internal combustion engine
DE102004002286A1 (en) * 2004-01-16 2005-08-11 Man B & W Diesel Ag fuel Injector
DE102004005452B4 (en) 2004-02-04 2014-01-09 Robert Bosch Gmbh Nozzle holder combination with direct-operated injection valve member
DE102005015735A1 (en) * 2005-04-06 2006-10-12 Robert Bosch Gmbh Fuel injector

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