WO2019076524A1 - Injector for metering liquid and gaseous fuel - Google Patents

Injector for metering liquid and gaseous fuel Download PDF

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Publication number
WO2019076524A1
WO2019076524A1 PCT/EP2018/073760 EP2018073760W WO2019076524A1 WO 2019076524 A1 WO2019076524 A1 WO 2019076524A1 EP 2018073760 W EP2018073760 W EP 2018073760W WO 2019076524 A1 WO2019076524 A1 WO 2019076524A1
Authority
WO
WIPO (PCT)
Prior art keywords
nozzle needle
shoulder
outer nozzle
injector
bore
Prior art date
Application number
PCT/EP2018/073760
Other languages
German (de)
French (fr)
Inventor
Jochen Wessner
Martin Katz
Original Assignee
Robert Bosch Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Priority to CN201880067756.4A priority Critical patent/CN111226033A/en
Publication of WO2019076524A1 publication Critical patent/WO2019076524A1/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
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/0248—Injectors
    • F02M21/0257—Details of the valve closing elements, e.g. valve seats, stems or arrangement of flow passages
    • F02M21/026—Lift valves, i.e. stem operated valves
    • F02M21/0263—Inwardly opening single or multi nozzle valves, e.g. needle valves
    • F02M21/0266—Hollow stem valves; Piston valves; Stems having a spherical tip
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02D19/0686—Injectors
    • F02D19/0694—Injectors operating with a plurality of fuels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/08—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels
    • F02D19/10—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels peculiar to compression-ignition engines in which the main fuel is gaseous
    • F02D19/105—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels peculiar to compression-ignition engines in which the main fuel is gaseous operating in a special mode, e.g. in a liquid fuel only mode for starting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D29/00—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
    • F02D29/02—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M43/00—Fuel-injection apparatus operating simultaneously on two or more fuels, or on a liquid fuel and another liquid, e.g. the other liquid being an anti-knock additive
    • F02M43/04—Injectors peculiar thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/004—Joints; Sealings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M55/00—Fuel-injection apparatus characterised by their fuel conduits or their venting means; Arrangements of conduits between fuel tank and pump F02M37/00
    • F02M55/008—Arrangement of fuel passages inside of injectors
    • 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
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
    • F02D19/0639—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels
    • F02D19/0642—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

Definitions

  • the invention relates to an injector, as used for dosing liquid and gaseous fuel, for example, to introduce these fuels in a combustion chamber of an internal combustion engine.
  • Injectors are known from the prior art with which both gaseous and liquid fuel can be metered into a combustion chamber of an internal combustion engine.
  • Such, for example from DE 10 2014 225 167 AI known injector has an outer nozzle needle, which is arranged longitudinally displaceable in an injector body.
  • the nozzle needle has at its combustion chamber-side end a sealing surface, with which it cooperates with a seat surface for opening and closing a Eindüsqueritess, can flow through the gaseous fuel from a pressure chamber within the injector.
  • the nozzle needle is guided in a cylindrical guide section in the injector body, wherein a leakage gap remains between the guide bore in the injector body and the nozzle needle.
  • a longitudinal bore is formed, in which an inner nozzle needle is arranged, the injection openings, which are formed within the outer nozzle needle, opens and closes.
  • the inner nozzle needle With the inner nozzle needle, a liquid fuel is metered, with which the longitudinal bore of the outer nozzle needle is filled.
  • a bore is provided, through the guide bore and the outer nozzle needle through into the longitudinal bore of the outer nozzle needle enough.
  • this inlet bore pierces the throttle gap, which exists between the outer nozzle needle and the guide bore in the injector, so that liquid fuel can diffuse into this throttle gap. Since the throttle gap opens into the filled with gaseous fuel pressure chamber, in this way always liquid fuel enters the pressure chamber, is entrained with the gas flow and so also introduced into the combustion chamber, where it burns. In normal operation of the fuel injection valve, this is not a problem, since only a very small amount of liquid fuel passes into the gas-filled pressure chamber and can be easily injected with the gas stream with. A small amount may even be desirable to both lubricate the outer nozzle needle and to bring some liquid fuel to the outer nozzle seat where it also lubricates and reduces wear.
  • the known fuel injector can also be used to inject only liquid fuel into the combustion chamber.
  • the outer nozzle needle is held in its closed position, so that the gas-filled pressure chamber remains closed, while the inner nozzle needle is moved and thereby dosed the liquid fuel.
  • This operating state can be approached specifically or be required, for example, when the gaseous fuel is not or not available with the required pressure.
  • a large amount of liquid fuel can pass through the throttle gap into the pressure space filled with gaseous fuel for a longer period of pure operation with liquid fuel until it is completely filled with liquid fuel. If the gas injection is resumed at a later time, then this liquid fuel must be pushed out of the pressure chamber, which can lead to uncontrolled combustion and affects the proper operation of the injector.
  • the injector according to the invention has the advantage that operation with liquid fuel is also problematic over a relatively long period of time. is possible without impairing the ability to inject gaseous fuel.
  • the injector has an injector body in which a pressure chamber which can be filled with gaseous fuel is formed, in which a piston-shaped, outer nozzle needle is arranged so as to be longitudinally displaceable, which opens and closes an injection cross section through its longitudinal movement, through which gaseous fuel can flow.
  • a guide portion is formed, with which the outer nozzle needle is guided in a guide bore of the injector, wherein between the guide portion and the guide bore, a throttle gap is formed.
  • the guide section of the outer nozzle needle is stepped, so that a shoulder is formed in the guide section, which shoulder lies opposite a shoulder formed in the injector body. Between the shoulder and the shoulder, an elastic sealing element is arranged, which is clamped between the shoulder and the shoulder for sealing the throttle gap when the outer nozzle needle is in its closed position.
  • the outer nozzle needle In an operation in which only liquid fuel is ejected, the outer nozzle needle remains in its closed position. However, the liquid fuel continues to penetrate into the throttle gap between the guide bore in the injector and the outer nozzle needle so that it would flow into the pressure chamber with the consequences already described above.
  • the sealing element which is clamped between the shoulder and the shoulder, the throttle gap is effectively sealed, so that even with a longer operation of the injector with liquid fuel sealing of the gaseous fuel filled pressure chamber is ensured against the liquid fuel. Even after prolonged operation with liquid fuel can thus easily be switched to a gas operation or to a gas and liquid operation.
  • a longitudinal bore is formed in the outer nozzle needle into which liquid fuel can be introduced.
  • This can be injected from there and serves, for example, to produce an ignitable mixture in the combustion chamber, which serves to ignite the gaseous fuel.
  • To supply the longitudinal bore with liquid fuel is provided in an advantageous manner that the throttle gap is connected to a supply bore for the liquid fuel.
  • the guide bore has two sections with different diameters, through which the shoulder is formed.
  • a stepped bore can be produced with little effort, so that a production is possible at low cost.
  • the shoulder is preferably formed annular disc-shaped and also the shoulder on the outer nozzle needle, so that the elastic sealing element can be clamped well between these two surfaces.
  • the sealing element is designed as a sealing ring, which is received in a further advantageous embodiment in an annular groove formed in the shoulder.
  • sealing rings are known as standard components in the prior art and can be produced at cost.
  • the desired surface pressure in the area between the shoulder and the heel can be achieved.
  • Figure 1 shows a longitudinal section through an injector according to the invention with its essential components
  • FIG. 2b shows two states of the injector, wherein the section of FIG. 1 denoted by II is shown enlarged. Description of the embodiment
  • FIG. 1 shows a longitudinal section of an injector according to the invention.
  • the injector 1 has an injector body 2 in which a pressure chamber 3 which can be filled with gaseous fuel is formed.
  • a pressure chamber 3 which can be filled with gaseous fuel is formed.
  • an outer nozzle needle 5 is arranged longitudinally displaceable, which is piston-shaped and at its lower in the drawing, the combustion chamber end facing a conical sealing surface 6, with the outer nozzle needle 5 with a nozzle seat 7 for opening and closing a Eindüsqueritess interacts.
  • the injection cross-section is here designed in the form of several injection openings 9, which point in the injector 2 obliquely outward.
  • the pressure chamber 3 can be filled with gaseous fuel at an injection pressure via a gas inlet bore 10 formed in the injector body 2, the gaseous fuel flowing through the annular space remaining between the outer nozzle needle 5 and the wall of the pressure chamber 3 to the nozzle seat 7 and between the sealing surface 6 and the nozzle seat 7 through into the Eindüsö Maschinenen. 9
  • the outer nozzle needle 5 In its end region facing away from the nozzle seat 7, the outer nozzle needle 5 forms a guide section 13, with which the outer nozzle needle 5 is guided in a guide bore 14. Between the guide portion 13 and the
  • the outer nozzle needle 5 With its end facing away from the nozzle seat 7, the outer nozzle needle 5 defines an outer control chamber 32, in which an outer closing spring 33 is arranged under Druckvor- voltage, so exerted by the outer closing spring 33, a force on the outer nozzle needle 5 in the direction of the nozzle seat 7 becomes.
  • a longitudinal bore 19 is formed, in which a piston-shaped, inner nozzle needle 20 is received longitudinally displaceable.
  • the inner nozzle needle 20 forms at its end an inner sealing surface 21, with which it cooperates with an inner nozzle seat 22, which is formed at the end of the longitudinal bore 19 in the outer nozzle needle 5, for opening and closing a plurality of injection openings 24.
  • the longitudinal bore 19 and thus the annular space remaining between the inner nozzle needle 20 and the wall of the bore 19 can be filled with a liquid fuel under high pressure, which when released injection openings 24 can be ejected through this.
  • the inner nozzle needle 20 defines together with the outer nozzle needle 5 an inner control chamber 29, in which an inner closing spring 30 is received under compressive bias, which exerts a closing force on the inner nozzle needle 20 in the direction of the inner nozzle seat 22.
  • an inlet bore 26 is formed in the injector body 2, which runs parallel to the outer nozzle needle 5 in the upper area of the injector body 2, finally kinks and opens into the longitudinal bore 19 of the outer nozzle needle 5.
  • the inlet bore 26 passes through the throttle gap 15, which is formed between the outer nozzle needle 5 and the guide bore 14, so that the throttle gap 15 is connected to the inlet bore 26.
  • a first inlet throttle 28 which branches off from the inlet bore 26 and is formed in the injector body 2 and in the outer nozzle needle 5.
  • the inner control chamber 29 is also connected via a flow restrictor, not shown in the drawing with a low pressure chamber, so that the fuel pressure within the inner control chamber 29 can be changed by opening and closing the drain throttle and the hydraulic closing force on the inner nozzle needle 20 is variable ,
  • a second inlet throttle 35 is furthermore formed in the injector body 2, so that the high fuel pressure in the inlet bore 26 also prevails in the outer control chamber 32.
  • the outer control chamber 32 is also connected via an outlet throttle 36 with the low-pressure chamber, so that the fuel pressure in the outer control chamber 32 can be adjusted and thus the hydraulic closing force on the outer nozzle needle 5.
  • the guide bore 14 is designed as a stepped bore and has a first
  • Section 114 with a larger diameter and a second section 214 with a smaller diameter are formed in the guide bore 14 on the injector body 2, which is annular disk-shaped and thus forms a right angle in cross-section with the longitudinal axis 27 of the outer nozzle needle 5.
  • the guide section 13 of the outer nozzle needle 5 also has two sections with different diameters, so that a throttle gap 15 is formed both between the outer nozzle needle 5 and the first section of the guide bore 114 and between the second guide section 214 and the outer nozzle needle 5.
  • FIG. 1 shows an enlarged view of the designated II section of Figure 1.
  • the elastic sealing element 18 is partially received in a formed in the shoulder 17 annular groove 23. If the outer nozzle needle 5 in its closed position, ie in contact with the nozzle seat 7, the elastic sealing element 18 is clamped between the shoulder 16 and the shoulder 17 and thereby seals the throttle gap 15. Via the inlet bore 26, which is connected to the throttle gap 15, liquid fuel is continuously introduced into the throttle gap 15 and would continue to flow without the elastic sealing element 18 into the pressure chamber 3. By the elastic sealing element 18 of this flow is prevented, as long as the outer nozzle needle 5 is in its closed position.
  • liquid fuel preferably diesel fuel
  • the sealing element 18 is again clamped between the shoulder 16 and the shoulder 17 and closes the throttle gap 15.
  • liquid fuel would flow continuously into the pressure chamber 3 without further measures, but would no longer be entrained by the gaseous fuel from there. Accordingly, the liquid fuel would accumulate in the pressure chamber 3 as long as the injector is operated only with liquid fuel.
  • the outer nozzle needle 15 remains closed and moves only the inner nozzle needle 20, so the injector according to the invention, however, the throttle gap 15 is sealed by the sealing element 18, so that even with prolonged operation of the pressure chamber 3 remains free of liquid fuel.
  • the injection of gaseous fuel can be resumed without problems without the pressure chamber 3 having to be emptied beforehand.

Abstract

The invention relates to an injector (1) for metering liquid and gaseous fuel, comprising an injector body (2) in which a pressure chamber (3) is formed that can be filled with gaseous fuel, wherein a piston-shaped outer nozzle needle (5) is arranged in said pressure chamber in a longitudinally movable manner, said nozzle needle opening and closing an injection cross-section (9), through which gaseous fuel can flow out of the pressure chamber (3), by means of the longitudinal movement of the nozzle needle. The outer nozzle needle (5) is equipped with a guide section (13), by means of which the outer nozzle needle (5) is guided in a guide bore (14) of the injector body (2) such that a throttle gap (15) is formed between the guide section (13) and the guide bore (14). The guide section (13) of the outer nozzle needle (5) is designed in a stepped manner such that a projecting section (16) which lies opposite a shoulder (17) formed in the injector body (2) is formed in the guide section (13). An elastic sealing element (18) is arranged between the projecting section (16) and the shoulder (17), said sealing element being clamped between the projecting section (16) and the shoulder (17) in order to seal the throttle gap (15) when the outer nozzle needle (5) is in the closed position.

Description

Beschreibung Titel  Description title
Injektor zum Dosieren von flüssigem und gasförmigem Kraftstoff  Injector for dosing liquid and gaseous fuel
Die Erfindung betrifft einen Injektor, wie er zum Dosieren von flüssigem und gasförmigem Kraftstoff Verwendung findet, beispielsweise um diese Kraftstoffe in einen Brennraum einer Brennkraftmaschine einzubringen. The invention relates to an injector, as used for dosing liquid and gaseous fuel, for example, to introduce these fuels in a combustion chamber of an internal combustion engine.
Stand der Technik State of the art
Aus dem Stand der Technik sind Injektoren bekannt, mit denen sowohl gasförmiger als auch flüssiger Kraftstoff in einen Brennraum einer Brennkraftmaschine eindosiert werden kann. Ein solcher, beispielsweise aus der DE 10 2014 225 167 AI bekannter Injektor weist eine äußere Düsennadel auf, die längsverschiebbar in einem Injektorkörper angeordnet ist. Die Düsennadel weist an ihrem brenn- raumseitigen Ende eine Dichtfläche auf, mit der sie mit einer Sitzfläche zum Öffnen und Schließen eines Eindüsquerschnitts zusammenwirkt, über den gasförmiger Kraftstoff aus einem Druckraum innerhalb des Injektors ausströmen kann. Die Düsennadel ist dabei in einem zylindrischen Führungsabschnitt im Injektorkörper geführt, wobei zwischen der Führungsbohrung im Injektorkörper und der Düsennadel ein Leckagespalt verbleibt. In der äußeren Düsennadel ist eine Längsbohrung ausgebildet, in der eine innere Düsennadel angeordnet ist, die Einspritzöffnungen, die innerhalb der äußeren Düsennadel ausgebildet sind, öffnet und schließt. Mit der inneren Düsennadel wird ein flüssiger Kraftstoff dosiert, mit dem die Längsbohrung der äußeren Düsennadel befüllt ist. Injectors are known from the prior art with which both gaseous and liquid fuel can be metered into a combustion chamber of an internal combustion engine. Such, for example from DE 10 2014 225 167 AI known injector has an outer nozzle needle, which is arranged longitudinally displaceable in an injector body. The nozzle needle has at its combustion chamber-side end a sealing surface, with which it cooperates with a seat surface for opening and closing a Eindüsquerschnitts, can flow through the gaseous fuel from a pressure chamber within the injector. The nozzle needle is guided in a cylindrical guide section in the injector body, wherein a leakage gap remains between the guide bore in the injector body and the nozzle needle. In the outer nozzle needle, a longitudinal bore is formed, in which an inner nozzle needle is arranged, the injection openings, which are formed within the outer nozzle needle, opens and closes. With the inner nozzle needle, a liquid fuel is metered, with which the longitudinal bore of the outer nozzle needle is filled.
Um den flüssigen Kraftstoff in die Längsbohrung der äußeren Düsennadel zu einzuleiten ist eine Bohrung vorgesehen, die durch die Führungsbohrung und die äußere Düsennadel hindurch bis in die Längsbohrung der äußeren Düsennadel reicht. Dabei durchsticht diese Zulaufbohrung den Drosselspalt, der zwischen der äußeren Düsennadel und der Führungsbohrung im Injektorkörper besteht, so dass flüssiger Kraftstoff in diesen Drosselspalt eindiffundieren kann. Da der Drosselspalt in den mit gasförmigem Kraftstoff befüllten Druckraum mündet, gelangt auf diese Weise stets flüssiger Kraftstoff in den Druckraum, wird mit dem Gasstrom mitgerissen und so ebenfalls in den Brennraum eingebracht, wo er verbrennt. Beim normalen Betrieb des Kraftstoffeinspritzventils stellt dies kein Problem dar, da nur eine sehr geringe Menge flüssiger Kraftstoff in den mit Gas gefüllten Druckraum gelangt und mit dem Gasstrom problemlos mit ausgespritzt werden kann. Eine geringe Menge kann sogar erwünscht sein, um einerseits die äußere Düsennadel zu schmieren und andererseits etwas flüssigen Kraftstoff auf den äußeren Düsensitz zu bringen, wo er ebenfalls eine Schmierung bewirkt und den Verschleiß mindert. To initiate the liquid fuel into the longitudinal bore of the outer nozzle needle, a bore is provided, through the guide bore and the outer nozzle needle through into the longitudinal bore of the outer nozzle needle enough. In this case, this inlet bore pierces the throttle gap, which exists between the outer nozzle needle and the guide bore in the injector, so that liquid fuel can diffuse into this throttle gap. Since the throttle gap opens into the filled with gaseous fuel pressure chamber, in this way always liquid fuel enters the pressure chamber, is entrained with the gas flow and so also introduced into the combustion chamber, where it burns. In normal operation of the fuel injection valve, this is not a problem, since only a very small amount of liquid fuel passes into the gas-filled pressure chamber and can be easily injected with the gas stream with. A small amount may even be desirable to both lubricate the outer nozzle needle and to bring some liquid fuel to the outer nozzle seat where it also lubricates and reduces wear.
Der bekannte Kraftstoffinjektor kann auch dafür verwendet werden, ausschließlich flüssigem Kraftstoff in den Brennraum einzuspritzen. Dazu wird die äußere Düsennadel in ihrer Schließstellung gehalten, so dass der mit Gas gefüllte Druckraum verschlossen bleibt, während die innere Düsennadel bewegt wird und dadurch den flüssigen Kraftstoff dosiert. Dieser Betriebszustand kann gezielt angefahren werden oder beispielsweise dann erforderlich sein, wenn der gasförmige Kraftstoff nicht oder nicht mit dem erforderlichen Druck zur Verfügung steht. Beim bekannten Kraftstoffinjektor kann bei einem länger dauernden reinen Betrieb mit flüssigem Kraftstoff eine große Menge flüssiger Kraftstoff über den Drosselspalt in den mit gasförmigem Kraftstoff gefüllten Druckraum gelangen, bis dieser vollständig mit flüssigem Kraftstoff gefüllt ist. Wird zu einem späteren Zeitpunkt die Gaseinblasung wieder aufgenommen, so muss dieser flüssige Kraftstoff aus dem Druckraum herausgedrückt werden, was zu einer unkontrollierten Verbrennung führen kann und den ordnungsgemäßen Betrieb des Injektors beeinträchtigt. The known fuel injector can also be used to inject only liquid fuel into the combustion chamber. For this purpose, the outer nozzle needle is held in its closed position, so that the gas-filled pressure chamber remains closed, while the inner nozzle needle is moved and thereby dosed the liquid fuel. This operating state can be approached specifically or be required, for example, when the gaseous fuel is not or not available with the required pressure. In the case of a known fuel injector, a large amount of liquid fuel can pass through the throttle gap into the pressure space filled with gaseous fuel for a longer period of pure operation with liquid fuel until it is completely filled with liquid fuel. If the gas injection is resumed at a later time, then this liquid fuel must be pushed out of the pressure chamber, which can lead to uncontrolled combustion and affects the proper operation of the injector.
Vorteile der Erfindung Advantages of the invention
Der erfindungsgemäße Injektor weist dem gegenüber den Vorteil auf, dass ein Betrieb nur mit flüssigem Kraftstoff auch über einen längeren Zeitraum problem- los möglich ist, ohne dass die Fähigkeit zur Eindüsung von gasförmigem Kraftstoff beeinträchtigt wird. Dazu weist der Injektor einen Injektorkörper auf, in dem ein mit gasförmigem Kraftstoff befüllbarer Druckraum ausgebildet ist, in dem eine kolbenförmige, äußere Düsennadel längsverschiebbar angeordnet ist, die durch ihre Längsbewegung einen Eindüsquerschnitt öffnet und schließt, durch den gasförmiger Kraftstoff ausströmen kann. An der äußeren Düsennadel ist ein Führungsabschnitt ausgebildet, mit dem die äußere Düsennadel in einer Führungsbohrung des Injektorkörpers geführt ist, wobei zwischen dem Führungsabschnitt und der Führungsbohrung ein Drosselspalt ausgebildet ist. Der Führungsab- schnitt der äußeren Düsennadel ist gestuft ausgebildet, so dass im Führungsabschnitt ein Absatz ausgebildet ist, der eine im Injektorkörper ausgebildete Schulter gegenüber liegt. Zwischen dem Absatz und der Schulter ist ein elastisches Dichtelement angeordnet, das zwischen dem Absatz und der Schulter zur Abdichtung des Drosselspalts eingeklemmt ist, wenn die äußere Düsennadel in ih- rer Schließstellung ist. In contrast, the injector according to the invention has the advantage that operation with liquid fuel is also problematic over a relatively long period of time. is possible without impairing the ability to inject gaseous fuel. For this purpose, the injector has an injector body in which a pressure chamber which can be filled with gaseous fuel is formed, in which a piston-shaped, outer nozzle needle is arranged so as to be longitudinally displaceable, which opens and closes an injection cross section through its longitudinal movement, through which gaseous fuel can flow. On the outer nozzle needle, a guide portion is formed, with which the outer nozzle needle is guided in a guide bore of the injector, wherein between the guide portion and the guide bore, a throttle gap is formed. The guide section of the outer nozzle needle is stepped, so that a shoulder is formed in the guide section, which shoulder lies opposite a shoulder formed in the injector body. Between the shoulder and the shoulder, an elastic sealing element is arranged, which is clamped between the shoulder and the shoulder for sealing the throttle gap when the outer nozzle needle is in its closed position.
Bei einem Betrieb, bei dem nur flüssiger Kraftstoff ausgespritzt wird, bleibt die äußere Düsennadel in ihrer Schließstellung. Der flüssige Kraftstoff dringt jedoch weiterhin in den Drosselspalt zwischen der Führungsbohrung im Injektorkörper und der äußeren Düsennadel ein, so dass dieser in den Druckraum einfließen würde mit den oben bereits beschriebenen Folgen. Durch das Dichtelement, das zwischen dem Absatz und der Schulter eingeklemmt ist, wird der Drosselspalt wirksam abgedichtet, so dass auch bei einem längeren Betrieb des Injektors nur mit flüssigem Kraftstoff eine Abdichtung des mit gasförmigem Kraftstoff gefüllten Druckraums gegen den flüssigen Kraftstoff gewährleistet ist. Auch nach einem längeren Betrieb mit flüssigem Kraftstoff kann damit problemlos auf einen Gasbetrieb umgestellt werden bzw. auf einen Gas- und Flüssigbetrieb. In an operation in which only liquid fuel is ejected, the outer nozzle needle remains in its closed position. However, the liquid fuel continues to penetrate into the throttle gap between the guide bore in the injector and the outer nozzle needle so that it would flow into the pressure chamber with the consequences already described above. By the sealing element which is clamped between the shoulder and the shoulder, the throttle gap is effectively sealed, so that even with a longer operation of the injector with liquid fuel sealing of the gaseous fuel filled pressure chamber is ensured against the liquid fuel. Even after prolonged operation with liquid fuel can thus easily be switched to a gas operation or to a gas and liquid operation.
In einer ersten vorteilhaften Ausgestaltung ist in der äußeren Düsennadel eine Längsbohrung ausgebildet, in die flüssiger Kraftstoff eingebracht werden kann.In a first advantageous embodiment, a longitudinal bore is formed in the outer nozzle needle into which liquid fuel can be introduced.
Dieser kann von dort eingespritzt werden und dient beispielsweise dazu, ein zündfähiges Gemisch im Brennraum herzustellen, das zur Entflammung des gasförmigen Kraftstoffs dient. Zur Versorgung der Längsbohrung mit flüssigem Kraftstoff ist in vorteilhafter Weise vorgesehen, dass der Drosselspalt mit einer Zu- laufbohrung für den flüssigen Kraftstoff verbunden ist. Dadurch ist der Drossel- spalt zwischen der äußeren Düsennadel und der Führungsbohrung mit dem flüssigen Kraftstoff während des Betriebs des Injektors verbunden, was in diesem Bereich eine Schmierwirkung erzeugt, die für den dauerhaften Betrieb des Injektors unerlässlich ist und für einen verschleißarmen Betrieb sorgt. This can be injected from there and serves, for example, to produce an ignitable mixture in the combustion chamber, which serves to ignite the gaseous fuel. To supply the longitudinal bore with liquid fuel is provided in an advantageous manner that the throttle gap is connected to a supply bore for the liquid fuel. As a result, the throttle gap between the outer nozzle needle and the guide bore connected to the liquid fuel during operation of the injector, which produces a lubricating effect in this area, which is essential for the permanent operation of the injector and ensures a low-wear operation.
In einer weiteren vorteilhaften Ausgestaltung weist die Führungsbohrung zwei Abschnitte mit unterschiedlichem Durchmesser auf, durch die die Schulter ausgebildet ist. Eine gestufte Bohrung lässt sich mit geringem Aufwand herstellen, so dass eine Fertigung kostengünstig möglich ist. Dabei ist die Schulter vorzugsweise ringscheibenförmig ausgebildet und ebenso der Absatz an der äußeren Düsennadel, so dass das elastische Dichtelement gut zwischen diesen beiden Flächen eingeklemmt werden kann. In a further advantageous embodiment, the guide bore has two sections with different diameters, through which the shoulder is formed. A stepped bore can be produced with little effort, so that a production is possible at low cost. In this case, the shoulder is preferably formed annular disc-shaped and also the shoulder on the outer nozzle needle, so that the elastic sealing element can be clamped well between these two surfaces.
In einer weiteren vorteilhaften Ausgestaltung ist das Dichtelement als ein Dichtring ausgebildet, der in weiterer vorteilhafter Ausgestaltung in einer in der Schulter ausgebildeten Ringnut aufgenommen ist. Solche Dichtringe sind als Standardbauteile im Stand der Technik bekannt und lassen sich kostenstündig herstellen. Je nach Material und nach Tiefe der Ringnut lässt sich die gewünschte Flächenpressung im Bereich zwischen der Schulter und dem Absatz erreichen. In a further advantageous embodiment, the sealing element is designed as a sealing ring, which is received in a further advantageous embodiment in an annular groove formed in the shoulder. Such sealing rings are known as standard components in the prior art and can be produced at cost. Depending on the material and the depth of the ring groove, the desired surface pressure in the area between the shoulder and the heel can be achieved.
Zeichnung drawing
In der Zeichnung ist ein Ausführungsbeispiel des erfindungsgemäßen Injektors gezeigt. Es zeigt In the drawing, an embodiment of the injector according to the invention is shown. It shows
Figur 1 einen Längsschnitt durch einen erfindungsgemäßen Injektor mit seinen wesentlichen Komponenten und Figure 1 shows a longitudinal section through an injector according to the invention with its essential components and
Figur 2a und Figure 2a and
Figur 2b zwei Zustände des Injektors, wobei der mit II bezeichnete Ausschnitt der Figur 1 vergrößert dargestellt ist. Beschreibung des Ausführungsbeispiels FIG. 2b shows two states of the injector, wherein the section of FIG. 1 denoted by II is shown enlarged. Description of the embodiment
In Figur 1 ist ein erfindungsgemäßer Injektor im Längsschnitt dargestellt. Der Injektor 1 weist einen Injektorkörper 2 auf, in dem ein mit gasförmigem Kraftstoff befüllbarer Druckraum 3 ausgebildet ist. Im Druckraum 3 ist eine äußere Düsennadel 5 längsverschiebbar angeordnet, die kolbenförmig ausgebildet ist und die an ihrem in der Zeichnung unteren, dem Brennraum zugewandten Ende eine konische Dichtfläche 6 aufweist, mit der die äußere Düsennadel 5 mit einem Düsensitz 7 zum Öffnen und Schließen eines Eindüsquerschnitts zusammenwirkt. Der Eindüsquerschnitt ist hier in Form von mehreren Eindüsöffnungen 9 ausgebildet, die im Injektor 2 schräg nach außen zeigen. Der Druckraum 3 ist über eine im Injektorkörper 2 ausgebildete Gaszuflussbohrung 10 mit gasförmigem Kraftstoff unter einem Eindüsdruck befüllbar, wobei der gasförmige Kraftstoff durch den Ringraum, der zwischen der äußeren Düsennadel 5 und der Wand des Druckraums 3 verbleibt, zum Düsensitz 7 strömt und zwischen der Dichtfläche 6 und dem Düsensitz 7 hindurch in die Eindüsöffnungen 9. FIG. 1 shows a longitudinal section of an injector according to the invention. The injector 1 has an injector body 2 in which a pressure chamber 3 which can be filled with gaseous fuel is formed. In the pressure chamber 3, an outer nozzle needle 5 is arranged longitudinally displaceable, which is piston-shaped and at its lower in the drawing, the combustion chamber end facing a conical sealing surface 6, with the outer nozzle needle 5 with a nozzle seat 7 for opening and closing a Eindüsquerschnitts interacts. The injection cross-section is here designed in the form of several injection openings 9, which point in the injector 2 obliquely outward. The pressure chamber 3 can be filled with gaseous fuel at an injection pressure via a gas inlet bore 10 formed in the injector body 2, the gaseous fuel flowing through the annular space remaining between the outer nozzle needle 5 and the wall of the pressure chamber 3 to the nozzle seat 7 and between the sealing surface 6 and the nozzle seat 7 through into the Eindüsöffnungen. 9
Die äußere Düsennadel 5 bildet in ihren dem Düsensitz 7 abgewandten Endbereich einen Führungsabschnitt 13 aus, mit dem die äußere Düsennadel 5 in einer Führungsbohrung 14 geführt ist. Zwischen dem Führungsabschnitt 13 und derIn its end region facing away from the nozzle seat 7, the outer nozzle needle 5 forms a guide section 13, with which the outer nozzle needle 5 is guided in a guide bore 14. Between the guide portion 13 and the
Führungsbohrung 14 ist ein Drosselspalt 15 ausgebildet, der die Beweglichkeit der äußeren Düsennadel 5 in der Führungsbohrung 14 sicherstellt. Mit ihrem dem Düsensitz 7 abgewandten Ende begrenzt die äußere Düsennadel 5 einen äußeren Steuerraum 32, in dem eine äußere Schließfeder 33 unter Druckvor- Spannung angeordnet ist, so dass durch die äußere Schließfeder 33 eine Kraft auf die äußere Düsennadel 5 in Richtung des Düsensitzes 7 ausgeübt wird. Guide bore 14 is a throttle gap 15 is formed, which ensures the mobility of the outer nozzle needle 5 in the guide bore 14. With its end facing away from the nozzle seat 7, the outer nozzle needle 5 defines an outer control chamber 32, in which an outer closing spring 33 is arranged under Druckvor- voltage, so exerted by the outer closing spring 33, a force on the outer nozzle needle 5 in the direction of the nozzle seat 7 becomes.
Im Inneren der äußeren Düsennadel 5 ist eine Längsbohrung 19 ausgebildet, in der eine kolbenförmige, innere Düsennadel 20 längsverschiebbar aufgenommen ist. Die innere Düsennadel 20 bildet an ihrem Ende eine innere Dichtfläche 21 aus, mit der sie mit einem inneren Düsensitz 22, der am Ende der Längsbohrung 19 in der äußeren Düsennadel 5 ausgebildet ist, zum Öffnen und Schließen mehrerer Einspritzöffnungen 24 zusammenwirkt. Die Längsbohrung 19 und damit der zwischen der inneren Düsennadel 20 und der Wand der Bohrung 19 verbleiben- de Ringraum ist mit einem flüssigen Kraftstoff unter hohem Druck befüllbar, der bei freigegebenen Einspritzöffnungen 24 durch diese ausgespritzt werden kann. Die innere Düsennadel 20 begrenzt zusammen mit der äußeren Düsennadel 5 einen inneren Steuerraum 29, in dem eine innere Schließfeder 30 unter Druckvorspannung aufgenommen ist, die eine Schließkraft auf die innere Düsennadel 20 in Richtung des inneren Düsensitzes 22 ausübt. Inside the outer nozzle needle 5, a longitudinal bore 19 is formed, in which a piston-shaped, inner nozzle needle 20 is received longitudinally displaceable. The inner nozzle needle 20 forms at its end an inner sealing surface 21, with which it cooperates with an inner nozzle seat 22, which is formed at the end of the longitudinal bore 19 in the outer nozzle needle 5, for opening and closing a plurality of injection openings 24. The longitudinal bore 19 and thus the annular space remaining between the inner nozzle needle 20 and the wall of the bore 19 can be filled with a liquid fuel under high pressure, which when released injection openings 24 can be ejected through this. The inner nozzle needle 20 defines together with the outer nozzle needle 5 an inner control chamber 29, in which an inner closing spring 30 is received under compressive bias, which exerts a closing force on the inner nozzle needle 20 in the direction of the inner nozzle seat 22.
Zur Zuführung des flüssigen Kraftstoffs ist im Injektorkörper 2 eine Zulaufbohrung 26 ausgebildet, die im oberen Bereich des Injektorkörpers 2 parallel zur äußeren Düsennadel 5 verläuft, schließlich abknickt und in die Längsbohrung 19 der äu- ßeren Düsennadel 5 mündet. Dabei durchquert die Zulaufbohrung 26 den Drosselspalt 15, der zwischen der äußeren Düsennadel 5 und der Führungsbohrung 14 ausgebildet ist, so dass der Drosselspalt 15 mit der Zulaufbohrung 26 verbunden ist. Zur Befüllung des inneren Druckraums 30 dient eine erste Zulaufdrossel 28, die von der Zulaufbohrung 26 abzweigt und im Injektorkörper 2 und in der äußeren Düsennadel 5 ausgebildet ist. Der innere Steuerraum 29 ist darüber hinaus über eine in der Zeichnung nicht dargestellte Ablaufdrossel mit einem Niederdruckraum verbindbar, so dass der Kraftstoff druck innerhalb des inneren Steuerraums 29 durch Öffnen und Schließen der Ablaufdrossel geändert werden kann und die hydraulische Schließkraft auf die innere Düsennadel 20 variierbar ist. For supplying the liquid fuel, an inlet bore 26 is formed in the injector body 2, which runs parallel to the outer nozzle needle 5 in the upper area of the injector body 2, finally kinks and opens into the longitudinal bore 19 of the outer nozzle needle 5. In this case, the inlet bore 26 passes through the throttle gap 15, which is formed between the outer nozzle needle 5 and the guide bore 14, so that the throttle gap 15 is connected to the inlet bore 26. For filling the inner pressure chamber 30 is a first inlet throttle 28, which branches off from the inlet bore 26 and is formed in the injector body 2 and in the outer nozzle needle 5. The inner control chamber 29 is also connected via a flow restrictor, not shown in the drawing with a low pressure chamber, so that the fuel pressure within the inner control chamber 29 can be changed by opening and closing the drain throttle and the hydraulic closing force on the inner nozzle needle 20 is variable ,
Zur Befüllung des äußeren Steuerraums 32 ist weiterhin im Injektorkörper 2 eine zweite Zulaufdrossel 35 ausgebildet, so dass der hohe Kraftstoffdruck in der Zulaufbohrung 26 auch im äußeren Steuerraum 32 herrscht. Der äußere Steuer- räum 32 ist darüber hinaus über eine Ablaufdrossel 36 mit dem Niederdruckraum verbindbar, so dass auch der Kraftstoffdruck im äußeren Steuerraum 32 eingestellt werden kann und damit die hydraulische Schließkraft auf die äußere Düsennadel 5. Die Führungsbohrung 14 ist als Stufenbohrung ausgeführt und weist einen erstenTo fill the outer control chamber 32, a second inlet throttle 35 is furthermore formed in the injector body 2, so that the high fuel pressure in the inlet bore 26 also prevails in the outer control chamber 32. The outer control chamber 32 is also connected via an outlet throttle 36 with the low-pressure chamber, so that the fuel pressure in the outer control chamber 32 can be adjusted and thus the hydraulic closing force on the outer nozzle needle 5. The guide bore 14 is designed as a stepped bore and has a first
Abschnitt 114 mit einem größeren Durchmesser und einen zweiten Abschnitt 214 mit einem kleineren Durchmesser auf. Durch die beiden Abschnitte 114, 214 ist in der Führungsbohrung 14 am Injektorkörper 2 eine Schulter 17 ausgebildet, die ringscheibenförmig ausgebildet ist und damit im Querschnitt gesehen einen rech- ten Winkel mit der Längsachse 27 der äußeren Düsennadel 5 bildet. Entspre- chend weist der Führungsabschnitt 13 der äußeren Düsennadel 5 ebenfalls zwei Abschnitte mit unterschiedlichem Durchmesser auf, so dass sowohl zwischen der äußeren Düsennadel 5 und dem ersten Abschnitt der Führungsbohrung 114 als auch zwischen dem zweiten Führungsabschnitt 214 und der äußeren Düsennadel 5 ein Drosselspalt 15 gebildet wird. Durch die beiden Führungsabschnitte 13 mit unterschiedlichem Durchmesser ist auch an der äußeren Düsennadel 5 ein Absatz 16 ausgebildet, der der Schulter 17 gegenüber liegt, wobei zwischen dem Absatz 16 und der Schalter 17 ein elastisches Dichtelement 18 angeordnet ist. Dazu zeigt Figur 2a eine vergrößerte Darstellung des mit II bezeichneten Ausschnitts der Figur 1. Das elastische Dichtelement 18 ist in einer in der Schulter 17 ausgebildeten Ringnut 23 teilweise aufgenommen. Ist die äußere Düsennadel 5 in ihrer Schließstellung, d.h. in Anlage am Düsensitz 7, so wird das elastische Dichtelement 18 zwischen dem Absatz 16 und der Schulter 17 eingeklemmt und dichtet dadurch den Drosselspalt 15 ab. Über die Zulaufbohrung 26, die mit dem Drosselspalt 15 verbunden ist, wird beständig flüssiger Kraftstoff in den Drosselspalt 15 eingebracht und würde ohne das elastische Dichtelement 18 weiter in den Druckraum 3 fließen. Durch das elastische Dichtelement 18 wird dieser Fluss verhindert, solange die äußere Düsennadel 5 in ihrer Schließstellung ist. Section 114 with a larger diameter and a second section 214 with a smaller diameter. Through the two sections 114, 214, a shoulder 17 is formed in the guide bore 14 on the injector body 2, which is annular disk-shaped and thus forms a right angle in cross-section with the longitudinal axis 27 of the outer nozzle needle 5. correspond Accordingly, the guide section 13 of the outer nozzle needle 5 also has two sections with different diameters, so that a throttle gap 15 is formed both between the outer nozzle needle 5 and the first section of the guide bore 114 and between the second guide section 214 and the outer nozzle needle 5. By the two guide portions 13 with different diameter, a shoulder 16 is formed on the outer nozzle needle 5, which is the shoulder 17 opposite, wherein between the shoulder 16 and the switch 17, an elastic sealing element 18 is arranged. For this purpose, Figure 2a shows an enlarged view of the designated II section of Figure 1. The elastic sealing element 18 is partially received in a formed in the shoulder 17 annular groove 23. If the outer nozzle needle 5 in its closed position, ie in contact with the nozzle seat 7, the elastic sealing element 18 is clamped between the shoulder 16 and the shoulder 17 and thereby seals the throttle gap 15. Via the inlet bore 26, which is connected to the throttle gap 15, liquid fuel is continuously introduced into the throttle gap 15 and would continue to flow without the elastic sealing element 18 into the pressure chamber 3. By the elastic sealing element 18 of this flow is prevented, as long as the outer nozzle needle 5 is in its closed position.
Eine Benetzung des Drosselspalts 15 durch den flüssigen Kraftstoff ist durchaus erwünscht, da der flüssige Kraftstoff, vorzugsweise Dieselkraftstoff, eine Wetting of the throttle gap 15 by the liquid fuel is quite desirable, since the liquid fuel, preferably diesel fuel, a
Schmierwirkung im Drosselspalt 15 entfaltet und für ein verschleißarmes Bewegen der äußeren Düsennadel 5 sorgt. Hebt die Düsennadel 5 mit ihrem Absatz 16 in ihrer Öffnungsstellung von der Schulter 17 und dem elastischen Dichtelement 18 ab, wie es Figur 2b zeigt, so fließt der flüssige Kraftstoff in den Drosselspalt 15 und weiter in den Druckraum 3. Der flüssige Kraftstoff, der in geringer Menge auf diese Weise in den Druckraum 3 gerät, wird bei der Gaseindüsung durch den gasförmigen Kraftstoff mitgerissen und über den Eindüsquerschnitt 9 in den Brennraum eingebracht. Die geringe Menge flüssigen Kraftstoffs hat auch den Vorteil, dass der Düsensitz 7 leicht benetzt und geschmiert wird, so dass auch der Verschleiß zwischen der Dichtfläche 6 und dem Düsensitz 7 gemindert wird. Fährt die äußere Düsennadel 5 zurück in ihre Schließstellung, so wird das Dichtelement 18 wieder zwischen dem Absatz 16 und der Schulter 17 eingeklemmt und verschließt den Drosselspalt 15. Beim Betrieb ausschließlich mit flüssigem Kraftstoff würde ohne weitere Maßnahmen beständig flüssiger Kraftstoff in den Druckraum 3 fließen, würde von dort jedoch nicht mehr durch den gasförmigen Kraftstoff mitgerissen. Entsprechend würde sich der flüssige Kraftstoff im Druckraum 3 ansammeln, solange der Injek- tor nur mit flüssigem Kraftstoff betrieben wird. Bleibt die äußere Düsennadel 15 geschlossen und bewegt sich nur die innere Düsennadel 20, so bleibt beim erfindungsgemäßen Injektor jedoch der Drosselspalt 15 durch das Dichtelement 18 abgedichtet, so dass auch bei längerem Betrieb der Druckraum 3 frei von flüssigem Kraftstoff bleibt. Damit kann nach Beendigung des reinen Flüssigkraftstoff- betriebs die Eindüsung von gasförmigem Kraftstoff ohne Probleme wieder aufgenommen werden, ohne dass der Druckraum 3 vorher geleert werden müsste. Deploys lubricating effect in the throttle gap 15 and ensures a low-wear moving the outer nozzle needle 5. Lifting the nozzle needle 5 with its shoulder 16 in its open position of the shoulder 17 and the elastic sealing element 18, as shown in Figure 2b, the liquid fuel flows into the throttle gap 15 and further into the pressure chamber 3. The liquid fuel in a small amount in this way in the pressure chamber 3 device is entrained in the gas injection by the gaseous fuel and introduced via the Eindüsquerschnitt 9 in the combustion chamber. The small amount of liquid fuel also has the advantage that the nozzle seat 7 is slightly wetted and lubricated, so that the wear between the sealing surface 6 and the nozzle seat 7 is reduced. If the outer nozzle needle 5 moves back into its closed position, then the sealing element 18 is again clamped between the shoulder 16 and the shoulder 17 and closes the throttle gap 15. When operating exclusively with liquid fuel, liquid fuel would flow continuously into the pressure chamber 3 without further measures, but would no longer be entrained by the gaseous fuel from there. Accordingly, the liquid fuel would accumulate in the pressure chamber 3 as long as the injector is operated only with liquid fuel. If the outer nozzle needle 15 remains closed and moves only the inner nozzle needle 20, so the injector according to the invention, however, the throttle gap 15 is sealed by the sealing element 18, so that even with prolonged operation of the pressure chamber 3 remains free of liquid fuel. Thus, after the end of the pure liquid fuel operation, the injection of gaseous fuel can be resumed without problems without the pressure chamber 3 having to be emptied beforehand.

Claims

Ansprüche claims
1. Injektor (1) zum Dosieren von flüssigem und gasförmigem Kraftstoff, mit einem Injektorkörper (2), in dem ein mit gasförmigem Kraftstoff befüllbarer Druckraum (3) ausgebildet ist, in dem eine kolbenförmige äußere Düsennadel (5) längsverschiebbar angeordnet ist, die durch ihre Längsbewegung einen Eindüsquerschnitts (9) öffnet und schließt, durch den gasförmiger Kraftstoff aus dem Druckraum (3) ausströmen kann, wobei an der äußeren Düsennadel (5) ein Führungsabschnitt (13) ausgebildet ist, mit dem die äußere Düsennadel (5) in einer Führungsbohrung (14) des Injektorkörpers (2) geführt ist, so dass zwischen dem Führungsabschnitt (13) und der Führungsbohrung (14) ein Drosselspalt (15) ausgebildet ist, 1. injector (1) for metering liquid and gaseous fuel, with an injector body (2) in which a gaseous fuel-filled pressure chamber (3) is formed, in which a piston-shaped outer nozzle needle (5) is arranged longitudinally displaceable through their longitudinal movement opens and closes a Eindüsquerschnitts (9) through which gaseous fuel from the pressure chamber (3) can flow, wherein on the outer nozzle needle (5) a guide portion (13) is formed with which the outer nozzle needle (5) in one Guide bore (14) of the injector body (2) is guided, so that between the guide portion (13) and the guide bore (14) is formed a throttle gap (15),
dadurch gekennzeichnet, dass  characterized in that
der Führungsabschnitt (13) der äußeren Düsennadel (5) gestuft ausbildet ist, so dass im Führungsabschnitt (13) ein Absatz (16) ausbildet ist, der einer im Injektorkörper (2) ausgebildeten Schulter (17) gegenüberliegt, wobei zwischen dem Absatz (16) und der Schulter (17) ein elastisches Dichtelement (18) angeordnet ist, das zwischen dem Absatz (16) und der Schulter (17) zur Abdichtung des Drosselspalts (15) eingeklemmt ist, wenn die äußere Düsennadel (5) in ihrer Schließstellung ist.  the guide section (13) of the outer nozzle needle (5) is formed stepped, so that in the guide section (13) a shoulder (16) is formed which is opposite to a shoulder (17) formed in the injector body (2), wherein between the shoulder (16 ) and the shoulder (17) an elastic sealing element (18) is arranged, which is clamped between the shoulder (16) and the shoulder (17) for sealing the throttle gap (15) when the outer nozzle needle (5) is in its closed position ,
2. Injektor nach Anspruch 1, dadurch gekennzeichnet, dass in der äußeren Düsennadel (5) eine Längsbohrung (19) ausgebildet ist, in die über eine Zulauf- bohrung (26) flüssiger Kraftstoff eingebracht werden kann. 2. An injector according to claim 1, characterized in that in the outer nozzle needle (5) has a longitudinal bore (19) is formed, into which via an inlet bore (26) liquid fuel can be introduced.
3. Injektor nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass der Drosselspalt (15; 115) mit der Zulaufbohrung (26) für flüssigen Kraftstoff verbunden ist. 3. Injector according to claim 1 or 2, characterized in that the throttle gap (15; 115) is connected to the inlet bore (26) for liquid fuel.
4. Injektor nach Anspruch 1, dadurch gekennzeichnet, dass die Führungsbohrung (14) zwei Abschnitte (114; 214) mit unterschiedlichem Durchmesser aufweist, zwischen denen die Schulter (17) ausgebildet ist. 4. An injector according to claim 1, characterized in that the guide bore (14) has two sections (114; 214) with different diameters, between which the shoulder (17) is formed.
5. Injektor nach Anspruch 1, dadurch gekennzeichnet, dass die Schulter (17) ringscheibenförmig ausgebildet ist. 5. An injector according to claim 1, characterized in that the shoulder (17) is annular disk-shaped.
6. Injektor nach Anspruch 1, dadurch gekennzeichnet, dass der Absatz (16) an der äußeren Düsennadel (5) ringscheibenförmig ausgebildet ist. 6. An injector according to claim 1, characterized in that the shoulder (16) on the outer nozzle needle (5) is annular disc-shaped.
7. Injektor nach Anspruch 1, dadurch gekennzeichnet, dass das elastische Dichtelement (18) als ein Dichtring ausgebildet ist. 7. An injector according to claim 1, characterized in that the elastic sealing element (18) is designed as a sealing ring.
8. Injektor nach Anspruch 7, dadurch gekennzeichnet, dass der Dichtring (18) zumindest teilweise in einer in der Schulter (17) ausgebildeten Ringnut (23) aufgenommen ist. 8. An injector according to claim 7, characterized in that the sealing ring (18) is at least partially received in an in the shoulder (17) formed annular groove (23).
PCT/EP2018/073760 2017-10-17 2018-09-04 Injector for metering liquid and gaseous fuel WO2019076524A1 (en)

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DE102017218527.9A DE102017218527A1 (en) 2017-10-17 2017-10-17 Injector for dosing liquid and gaseous fuel

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DE102020006653A1 (en) * 2020-10-30 2022-05-05 Daimler Truck AG Injector sleeve for an injector, as well as injection device and internal combustion engine

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