WO2005119049A1 - Injection valve - Google Patents

Injection valve Download PDF

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Publication number
WO2005119049A1
WO2005119049A1 PCT/EP2005/051994 EP2005051994W WO2005119049A1 WO 2005119049 A1 WO2005119049 A1 WO 2005119049A1 EP 2005051994 W EP2005051994 W EP 2005051994W WO 2005119049 A1 WO2005119049 A1 WO 2005119049A1
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WO
WIPO (PCT)
Prior art keywords
manganese
injection valve
recess
piezo actuator
stack
Prior art date
Application number
PCT/EP2005/051994
Other languages
German (de)
French (fr)
Inventor
Günter LEWENTZ
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2005119049A1 publication Critical patent/WO2005119049A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/166—Selection of particular materials
    • 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
    • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
    • F02M61/167—Means for compensating clearance or thermal expansion

Definitions

  • the invention relates to an injection valve, in particular an injection valve for metering fuel into an internal combustion engine.
  • an injection valve is known with an injector housing which has a recess.
  • a piezo actuator is also assigned to the injection valve, which is arranged in the recess of the injector housing and which comprises a stack of piezoelectric elements.
  • the piezo Actuator is inserted into a tubular spring, which is firmly connected at its axial ends to caps, by means of which a preload force caused by the tubular spring is introduced into the stack of piezoelectric elements.
  • Two bellows are arranged in the recess of the injector housing, which ensure that the piezoelectric actuator does not come into contact with fuel.
  • the injector housing which is regularly made of steel, and the stack of piezoelectric elements have significantly different coefficients of thermal expansion.
  • the stack of piezoelectric elements has a very low coefficient of thermal expansion and the injector housing has a significantly higher coefficient of thermal expansion.
  • a thermal compensating element in the piezo actuator in the axial connection to the stack of piezoelectric elements and to form the latter from aluminum.
  • the object of the invention is to provide an injection valve that simply enables precise control of the injection valve.
  • the invention is characterized by an injection valve with an injector housing, which has a recess, and with a piezo actuator, which in the recess of the injector is arranged and which comprises a stack of piezoelectric elements and a thermal compensation element which consists of a manganese-copper-nickel alloy.
  • the manganese-copper-nickel alloy can also be referred to as a manganese-based alloy. It is characterized by a high temperature coefficient. It is also characterized by a high modulus of elasticity and thus enables very little useful stroke of the piezo actuator to be lost when the piezoelectric elements are lengthened under high load by supplying appropriate electrical energy to the piezo actuator.
  • a low level of spring can also be ensured if, for example, a valve which is driven by the piezo actuator is moved out of its closed position.
  • the manganese-copper-nickel alloy has a proportion of approximately 72% by weight of manganese, 18% by weight of copper and 10% by weight of nickel.
  • the manganese-copper-nickel alloy has a coefficient of thermal expansion ⁇ of approximately 28 x 10- ⁇ 1 / K in a temperature range of approximately 0 to 200 ° C. In contrast to aluminum, the coefficient of thermal expansion is thus approximately 15% higher ,
  • the injection valve can thus be made correspondingly more compact.
  • the manganese-copper-nickel alloy also has an elastic modulus of approx. 125,000 N / mm2. The modulus of elasticity is thus almost twice as high as that of aluminum. In this way, a fuel mass to be metered by means of the injection valve can be improved in the reproducibility of its metering and thus even very small amounts of fuel can be metered very precisely.
  • the single figure shows an injection valve which has an injector housing 1 which has a recess 2 in the injector housing 1.
  • a piezo actuator which is coupled to a transmitter 6, is inserted into the recess 2.
  • the transmitter 6 is arranged in a leakage space 8.
  • the switching valve is coupled to the piezo actuator via the transmitter 6 and is driven by it, that is to say the switching position of the switching valve 10 is set by means of the piezo actuator.
  • the switching valve 10 is arranged in a valve plate 12.
  • the injection valve further comprises a needle guide body 14 and a nozzle body 16.
  • the valve plate 12, the needle guide body 14 and the nozzle body 16 form a nozzle assembly which is fastened to the injector housing 1 by means of a nozzle clamping nut 18.
  • the needle guide body 14 has a recess which is continued as a recess of the nozzle body 16 in the nozzle body 16 and in which a nozzle needle 24 is arranged.
  • the nozzle needle 24 is guided in the needle guide body 14.
  • a nozzle spring 26 biases the nozzle needle 24 into a closed position in which it prevents fuel flow through an injection nozzle 28.
  • a control chamber 30 is formed, which is hydraulically coupled to a high-pressure bore 32 via an inlet throttle. If the switching valve 10 is in its closed position, the control chamber 30 is hydraulically decoupled from the leakage chamber 8. This has the consequence that after the switching valve 10 is closed, the pressure in the control chamber 30 essentially adjusts to the pressure in the high-pressure bore 32.
  • the high-pressure bore 32 is hydraulically coupled to a high-pressure fuel reservoir and is thus supplied with fuel under a pressure of, for example, up to 2000 bar.
  • a pressure in the closing direction of the nozzle needle 24 is exerted on an end face of the nozzle needle 24 via the control chamber 30 due to the fluid pressure in the control chamber 30.
  • the nozzle needle 24 furthermore has a shoulder axially spaced apart from its end face, which is acted upon by fluid that flows through the high-pressure bore 32 in such a way that an opening force acts on the nozzle needle 24. Outside of its closed position, the nozzle needle 24 releases the fuel flow through the injection nozzle 28. Whether the nozzle needle 24 is in its closed position or outside its closed position depends on whether the force which is caused on the shoulder of the nozzle needle 24 by the pressure of the fluid there is greater or less than the force which is caused by the nozzle spring 26 and the pressure acting on the end face of the nozzle needle 24.
  • the switching valve 10 If the switching valve 10 is in its open position, fluid flows from the control chamber 30 through the switching valve 10 into the leakage chamber 8. With a suitable dimensioning of the inlet throttle, the pressure in the control chamber 30 then drops, which ultimately leads to a movement of the nozzle needle 24 out of it Closing position leads out.
  • the pressure of the fluid in the le- Storage space 8 is significantly lower than the pressure of the fluid in high-pressure bore 32.
  • the piezo actuator comprises a stack 34 of piezoelectric elements and a thermal compensating element 36.
  • the stack of piezoelectric elements 34 and the thermal compensating element 36 are introduced into a tubular spring.
  • the tubular spring is welded at its one axial end to a first cap, which can optionally be designed as the transmitter 6.
  • the tubular spring is welded to a fixing element 38.
  • the Bourdon tube is under a predetermined preload and thus prestresses the stack of piezoelectric elements with a predeterminable force.
  • the fixing element 38 is preferably connected to the injector housing 1 in a positive and / or non-positive manner, in particular caulking.
  • the thermal compensation element 36 consists of a manganese-copper-nickel alloy, which is referred to below as a manganese-based alloy.
  • the thermal compensating element 36 is preferably made of a block, which is preferably cylindrical in shape of the manganese-based alloy.
  • the manganese base alloy advantageously consists of approximately 72% by weight of manganese, approximately 18% by weight of copper and approximately 10% by weight of nickel. It has a coefficient of thermal expansion of approximately 28 x 10 -6 1 / K in the temperature range from 0 to 200 ° C.
  • the axial length of the thermal compensation element 36 is selected such that the piezo actuator has the same thermal expansion behavior as that Material from which the injector housing 1 is made.
  • the switching behavior of the piezo actuator is constant with regard to the control of the switching valve 10 supported.
  • the high stiffness of the manganese base alloy of the thermal compensating element 36 which is characterized in particular by a high manganese content, ensures that when the stack 34 of the piezoelectric elements is lengthened by the high force which also acts on the thermal compensating element 36 from the valve 10 , only a small useful stroke of the stack 34 of the piezoelectric elements is lost.
  • the control of the stack 34 of the piezoelectric elements can take place with a very high degree of efficiency.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

An injection valve comprising an injector housing (1) provided with a recess (2), also comprising a piezo-actuator which is arranged in the recess (2) of the injector housing (1) and which comprises a stack of piezo-electric element and a thermal compensation element (36) which consists of a manganese-copper-nickel alloy.

Description

Beschreibungdescription
Einspritz entilInjection entil
Die Erfindung betrifft ein Einspritzventil, insbesondere ein Einspritzventil zum Zumessen von Kraftstoff in eine Brennkraftmaschine .The invention relates to an injection valve, in particular an injection valve for metering fuel into an internal combustion engine.
Immer strengere gesetzliche Vorschriften bezüglich der zulässigen Schadstoff-Emissionen von Brennkraf maschinen, die in Kraftfahrzeugen angeordnet sind, machen es erforderlich diverse Maßnahmen vorzunehmen, durch die die Schadstoff- Emissionen gesenkt werden. Ein Ansatzpunkt hierbei ist, die von der Brennkraftmaschine erzeugten Schadstoff-Emissionen zu senken. Insbesondere die Bildung von Ruß ist stark abhängig von der Aufbereitung des Lu t/Kra tstoffgemisches in dem jeweiligen Zylinder der Brennkraftmaschine. Um eine sehr gute Gemischaufbereitung zu erreichen, wird Kraftstoff zunehmend unter sehr hohem Druck zugemessen. Im Falle von Diesel- Brennkraftmaschinen betragen die Kraftstoffdrücke bis zu 2000 bar. Für derartige Anwendungen setzen sich zunehmend Einspritzventile durch mit einem Piezo-Aktuator. Derartige Einspritzventile zeichnen sich aus durch sehr kurze Ansprechzeiten des als Stellantrieb ausgebildeten Piezo-Aktuators . Sie ermöglichen so gegebenenfalls auch mehrfache Einspritzungen während eines Arbeitszyklusses eines Zylinders der Brennkraftmaschine .Ever stricter legal regulations regarding the permissible pollutant emissions of internal combustion engines, which are arranged in motor vehicles, make it necessary to take various measures by which the pollutant emissions are reduced. One starting point here is to reduce the pollutant emissions generated by the internal combustion engine. In particular, the formation of soot is heavily dependent on the processing of the air / fuel mixture in the respective cylinder of the internal combustion engine. In order to achieve a very good mixture preparation, fuel is increasingly metered under very high pressure. In the case of diesel engines, the fuel pressures are up to 2000 bar. For such applications, injection valves with a piezo actuator are becoming increasingly popular. Such injection valves are characterized by very short response times of the piezo actuator designed as an actuator. In this way, they also enable multiple injections during a working cycle of a cylinder of the internal combustion engine.
Aus der EP 1 111 230 A ist ein Einspritzventil bekannt mit einem Injektorgehäuse, das eine Ausnehmung aufweist. Dem Einspritzventil ist ferner ein Piezo-Aktuator zugeordnet, der in der Ausnehmung des Injektorgehäuses angeordnet ist und der einen Stapel piezoelektrischer Elemente umfasst. Der Piezo- Aktuator ist in eine Rohrfeder eingebracht, die an ihren axialen Enden mit Kappen fest verbunden ist, über die eine Vorspannungskraft hervorgerufen durch die Rohrfeder in den Stapel piezoelektrischer Elemente eingeleitet wird. In der Ausnehmung des Injektorgehäuses sind zwei Faltenbalge angeordnet, die gewährleisten, dass der piezoelektrische Aktuator nicht mit Kraftstoff in Kontakt kommt.From EP 1 111 230 A an injection valve is known with an injector housing which has a recess. A piezo actuator is also assigned to the injection valve, which is arranged in the recess of the injector housing and which comprises a stack of piezoelectric elements. The piezo Actuator is inserted into a tubular spring, which is firmly connected at its axial ends to caps, by means of which a preload force caused by the tubular spring is introduced into the stack of piezoelectric elements. Two bellows are arranged in the recess of the injector housing, which ensure that the piezoelectric actuator does not come into contact with fuel.
Das Injektorgehäuse, das regelmäßig aus Stahl hergestellt ist, und der Stapel piezoelektrischer Elemente weisen erheblich unterschiedliche thermische Ausdehnungskoeffizienten auf. So hat der Stapel piezoelektrischer Elemente einen sehr geringen thermischen Ausdehnungskoeffizienten und das Injektorgehäuse einen deutlich höheren thermischen Ausdehnungskoeffizienten. Bei einem Einsatz des Einspritzventils in einer Brennkraftmaschine muss dieses bei sehr unterschiedlichen Temperaturen betrieben werden können. Zum Ausgleichen der unterschiedlichen thermischen Ausdehnungskoef izienten ist es bekannt, in dem Piezo-Aktuator ein thermisches Ausgleichselement im axialen Anschluss an den Stapel der piezoelektrischen Elemente anzuordnen und dieses aus Aluminium auszubilden.The injector housing, which is regularly made of steel, and the stack of piezoelectric elements have significantly different coefficients of thermal expansion. For example, the stack of piezoelectric elements has a very low coefficient of thermal expansion and the injector housing has a significantly higher coefficient of thermal expansion. When the injection valve is used in an internal combustion engine, it must be possible to operate it at very different temperatures. To compensate for the different coefficients of thermal expansion, it is known to arrange a thermal compensating element in the piezo actuator in the axial connection to the stack of piezoelectric elements and to form the latter from aluminum.
Die Aufgabe der Erfindung ist es, ein Einspritzventil zu schaffen, das einfach ein präzises Steuern des Einspritzventils ermöglicht.The object of the invention is to provide an injection valve that simply enables precise control of the injection valve.
Die Aufgabe wird gelöst durch die Merkmale des unabhängigen Patentanspruchs. Eine vorteilhafte Ausgestaltung der Erfindung ergibt sich aus dem Unteranspruch.The object is achieved by the features of the independent claim. An advantageous embodiment of the invention results from the subclaim.
Die Erfindung zeichnet sich aus durch ein Einspritzventil mit einem Injektorgehäuse, das eine Ausnehmung aufweist, und mit einem Piezo-Aktuator, der in der Ausnehmung des Injektorge- häuses angeordnet ist und der einen Stapel piezoelektrischer Elemente und ein thermisches Ausgleichselement umfasst, das aus einer Mangan-Kupfer-Nickel-Legierung besteht. Die Mangan- Kupfer-Nickel-Legierung kann auch als Manganbasislegierung bezeichnet werden. Sie zeichnet sich aus durch einen hohen Temperaturkoeffizienten. Sie zeichnet sich ferner aus durch ein hohes Elastizitätsmodul und ermöglicht so, dass bei einem Längen der piezoelektrischen Elemente unter hoher Last durch Zuführen einer entsprechenden elektrischen Energie zu dem Piezo-Aktuator sehr wenig Nutzhub des Piezo-Aktuators verloren geht. Darüber hinaus kann auch so ein geringes Federn gewährleistet werden, wenn beispielsweise ein Ventil, das durch den Piezo-Aktuator angetrieben wird, aus seiner Ξchließstel- lung herausbewegt wird.The invention is characterized by an injection valve with an injector housing, which has a recess, and with a piezo actuator, which in the recess of the injector is arranged and which comprises a stack of piezoelectric elements and a thermal compensation element which consists of a manganese-copper-nickel alloy. The manganese-copper-nickel alloy can also be referred to as a manganese-based alloy. It is characterized by a high temperature coefficient. It is also characterized by a high modulus of elasticity and thus enables very little useful stroke of the piezo actuator to be lost when the piezoelectric elements are lengthened under high load by supplying appropriate electrical energy to the piezo actuator. In addition, a low level of spring can also be ensured if, for example, a valve which is driven by the piezo actuator is moved out of its closed position.
In einer vorteilhaften Ausgestaltung der Erfindung weist die Mangan-Kupfer-Nickel-Legierung einen Anteil in etwa 72 Gew-% Mangan, 18 Gew-% Kupfer und 10 Gew-% Nickel auf. So hat die Mangan-Kupfer-Nickel-Legierung einen thermischen Ausdehnungskoeffizienten α von in etwa 28 x 10-^ 1/K in einem Temperaturbereich von etwa 0 bis 200° C. Im Gegensatz zu Aluminium ist der thermische Ausdehnungskoeffizient somit in etwa 15 % höher. Das Einspritzventil kann so entsprechend kompakter ausgebildet werden. Ferner hat in diesem Fall die Mangan- Kupfer-Nickel-Legierung ein Elastizitätsmodul von ca. 125.000 N/mm2. Das Elastizitätsmodul ist somit fast doppelt so hoch wie das von Aluminium. Auf diese Weise kann einfach eine mittels des Einspritzventils zuzumessende Kraftstoffmasse in der Reproduzierbarkeit ihres Zumessens verbessert werden und somit auch kleinste Kraftstoffmengen sehr präzise zugemessen werden. In an advantageous embodiment of the invention, the manganese-copper-nickel alloy has a proportion of approximately 72% by weight of manganese, 18% by weight of copper and 10% by weight of nickel. The manganese-copper-nickel alloy has a coefficient of thermal expansion α of approximately 28 x 10- ^ 1 / K in a temperature range of approximately 0 to 200 ° C. In contrast to aluminum, the coefficient of thermal expansion is thus approximately 15% higher , The injection valve can thus be made correspondingly more compact. In this case, the manganese-copper-nickel alloy also has an elastic modulus of approx. 125,000 N / mm2. The modulus of elasticity is thus almost twice as high as that of aluminum. In this way, a fuel mass to be metered by means of the injection valve can be improved in the reproducibility of its metering and thus even very small amounts of fuel can be metered very precisely.
Ausführungsbeispiele der Erfindung sind im Folgenden anhand der schematischen Zeichnung beispielhaft erläutert.Exemplary embodiments of the invention are explained below using the schematic drawing as an example.
Die einzige Figur zeigt ein Einspritzventil, das ein Injektorgehäuse 1 hat, das eine Ausnehmung 2 des Injektorgehäuses 1 aufweist. In die Ausnehmung 2 ist ein Piezo-Aktuator eingesetzt, der mit einem Übertrager 6 gekoppelt ist. Der Übertrager 6 ist in einem Leckageraum 8 angeordnet. Ein Schaltventil 10, das bevorzugt als Servoventil ausgebildet ist, ist so angeordnet, dass es abhängig von seiner Schaltstellung ein Le- ckagefluid, das in dieser Ausführungsform bevorzugt der Kraftstoff ist, absteuert. Das Schaltventil ist über den Ü- bertrager 6 mit dem Piezo-Aktuator gekoppelt und wird von ihm angetrieben, das heißt die Schaltstellung des Schaltventils 10 wird mittels des Piezo-Aktuators eingestellt. Das Schaltventil 10 ist in einer Ventilplatte 12 angeordnet.The single figure shows an injection valve which has an injector housing 1 which has a recess 2 in the injector housing 1. A piezo actuator, which is coupled to a transmitter 6, is inserted into the recess 2. The transmitter 6 is arranged in a leakage space 8. A switching valve 10, which is preferably designed as a servo valve, is arranged in such a way that, depending on its switching position, it controls a leakage fluid, which in this embodiment is preferably the fuel. The switching valve is coupled to the piezo actuator via the transmitter 6 and is driven by it, that is to say the switching position of the switching valve 10 is set by means of the piezo actuator. The switching valve 10 is arranged in a valve plate 12.
Das Einspritzventil umfasst ferner einen Nadelführungskörper 14 und einen Düsenkörper 16. Die Ventilplatte 12, der Nadelführungskörper 14 und der Düsenkörper 16 bilden eine Düsenbaugruppe, die mittels einer Düsenspannmutter 18 an dem Injektorgehäuse 1 befestigt ist.The injection valve further comprises a needle guide body 14 and a nozzle body 16. The valve plate 12, the needle guide body 14 and the nozzle body 16 form a nozzle assembly which is fastened to the injector housing 1 by means of a nozzle clamping nut 18.
Der Nadelführungskörper 14 hat eine Ausnehmung, die als Ausnehmung des Düsenkörpers 16 in dem Düsenkörper 16 fortgesetzt ist und in der eine Düsennadel 24 angeordnet ist. Die Düsennadel 24 ist in dem Nadel ührungskörper 14 geführt. Eine Düsenfeder 26 spannt die Düsennadel 24 in eine Schließposition vor, in der sie einen Kraftstofffluss durch eine Einspritzdüse 28 unterbindet.The needle guide body 14 has a recess which is continued as a recess of the nozzle body 16 in the nozzle body 16 and in which a nozzle needle 24 is arranged. The nozzle needle 24 is guided in the needle guide body 14. A nozzle spring 26 biases the nozzle needle 24 into a closed position in which it prevents fuel flow through an injection nozzle 28.
An dem axialen Ende der Düsennadel 24, das hingewandt ist zu der Ventilplatte 12, ist ein Steuerraum 30 ausgebildet, der über eine Zulaufdrossel mit einer Hochdruckbohrung 32 hydraulisch gekoppelt ist. Befindet sich das Schaltventil 10 in seiner Schließstellung, so ist der Steuerraum 30 hydraulisch entkoppelt von dem Leckageraum 8. Dies hat zur Folge, dass sich nach einem Schließen des Schaltventils 10 der Druck in dem Steuerraum 30 im wesentlichen dem Druck in der Hochdruckbohrung 32 angleicht. Die Hochdruckbohrung 32 ist beim Einsatz des Einspritzventils in einer Brennkraftmaschine mit einem Kraftstoffhochdruckspeicher hydraulisch gekoppelt und wird so mit Kraftstoff unter einem Druck von beispielsweise bis zu 2000 bar versorgt. Über den Steuerraum 30 wird aufgrund des Fluiddrucks in dem Steuerraum 30 auf eine Stirnfläche der Düsennadel 24 ein Druck in Schließrichtung der Düsennadel 24 ausgeübt. Die Düsennadel 24 weist ferner axial beabstandet zu ihrer Stirnfläche einen Absatz auf, der mit Fluid, das durch die Hochdruckbohrung 32 strömt, derart beaufschlagt wird, dass eine öffnend wirkende Kraft auf die Düsennadel 24 wirkt. Außerhalb ihrer Schließposition gibt die Düsennadel 24 einen den Kraftstofffluss durch die Einspritzdüse 28 frei. Ob die Düsennadel 24 sich in ihrer Schließposition oder außerhalb ihrer Schließposition befindet hängt davon ab, ob die Kraft, die an dem Absatz der Düsennadel 24 durch den dort herrschenden Druck des Fluids hervorgerufen wird, größer oder kleiner ist als die Kraft, die durch die Düsenfeder 26 und den auf die Stirnfläche der Düsennadel 24 einwirkenden Druck hervorgerufen wird.At the axial end of the nozzle needle 24, which faces the valve plate 12, a control chamber 30 is formed, which is hydraulically coupled to a high-pressure bore 32 via an inlet throttle. If the switching valve 10 is in its closed position, the control chamber 30 is hydraulically decoupled from the leakage chamber 8. This has the consequence that after the switching valve 10 is closed, the pressure in the control chamber 30 essentially adjusts to the pressure in the high-pressure bore 32. When the injection valve is used in an internal combustion engine, the high-pressure bore 32 is hydraulically coupled to a high-pressure fuel reservoir and is thus supplied with fuel under a pressure of, for example, up to 2000 bar. A pressure in the closing direction of the nozzle needle 24 is exerted on an end face of the nozzle needle 24 via the control chamber 30 due to the fluid pressure in the control chamber 30. The nozzle needle 24 furthermore has a shoulder axially spaced apart from its end face, which is acted upon by fluid that flows through the high-pressure bore 32 in such a way that an opening force acts on the nozzle needle 24. Outside of its closed position, the nozzle needle 24 releases the fuel flow through the injection nozzle 28. Whether the nozzle needle 24 is in its closed position or outside its closed position depends on whether the force which is caused on the shoulder of the nozzle needle 24 by the pressure of the fluid there is greater or less than the force which is caused by the nozzle spring 26 and the pressure acting on the end face of the nozzle needle 24.
Befindet sich das Schaltventil 10 in seiner Offenstellung, so strömt Fluid von dem Steuerraum 30 durch das Schaltventil 10 hinein in den Leckageraum 8. Bei geeigneter Dimensionierung der Zulaufdrossel sinkt dann der Druck in dem Steuerraum 30, was schließlich zu einer Bewegung der Düsennadel 24 aus ihrer Schließposition heraus führt. Der Druck des Fluids in dem Le- ckageraum 8 ist deutlich geringer als der Druck des Fluids in der Hochdruckbohrung 32.If the switching valve 10 is in its open position, fluid flows from the control chamber 30 through the switching valve 10 into the leakage chamber 8. With a suitable dimensioning of the inlet throttle, the pressure in the control chamber 30 then drops, which ultimately leads to a movement of the nozzle needle 24 out of it Closing position leads out. The pressure of the fluid in the le- Storage space 8 is significantly lower than the pressure of the fluid in high-pressure bore 32.
Der Piezo-Aktuator umfasst einen Stapel 34 piezoelektrischer Elemente und ein thermisches Ausgleichselement 36. Der Stapel piezoelektrischer Elemente 34 und das thermische Ausgleichselement 36 sind in eine Rohrfeder eingebracht. Die Rohrfeder ist an ihrem einen axialen Ende mit einer ersten Kappe verschweißt, die gegebenenfalls als der Übertrager 6 ausgebildet sein kann . An ihrem anderen axialen Ende ist die Rohrfeder mit einem Fixierelement 38 verschweißt. Die Rohrfeder steht unter einer vorgegebenen Vorspannung und spannt so den Stapel der piezoelektrischen Elemente mit einer vorgebbaren Kraft vor. Das Fixierelement 38 ist bevorzugt mit dem Injektorgehäuse 1 form- und/oder kraftschlüssig verbunden, insbesondere verstemm .The piezo actuator comprises a stack 34 of piezoelectric elements and a thermal compensating element 36. The stack of piezoelectric elements 34 and the thermal compensating element 36 are introduced into a tubular spring. The tubular spring is welded at its one axial end to a first cap, which can optionally be designed as the transmitter 6. At its other axial end, the tubular spring is welded to a fixing element 38. The Bourdon tube is under a predetermined preload and thus prestresses the stack of piezoelectric elements with a predeterminable force. The fixing element 38 is preferably connected to the injector housing 1 in a positive and / or non-positive manner, in particular caulking.
Das thermische Ausgleichselement 36 besteht aus einer Mangan- Kupfer-Nickel-Legierung, die im Folgenden als Manganbasislegierung bezeichnet ist. Das thermische Ausgleichselement 36 ist bevorzugt aus einem Block, der vorzugsweise zylinderför- mig ist der Manganbasislegierung ausgebildet. Die Manganbasislegierung besteht vorteilhafterweise in etwa aus 72 Gew-% Mangan, in etwa 18 Gew-% Kupfer und in etwa 10 Gew-% Nickel. Sie hat einen Temperaturausdehnungskoeffizienten von in etwa 28 x 10-6 1/K in dem Temperaturbereich von 0 bis 200° C. Die axiale Länge des thermischen Ausgleichselements 36 ist derart gewählt, dass der Piezo-Aktuator insgesamt in das gleiche thermische Dehnungsverhalten hat wie das Material , aus dem das Injektorgehäuse 1 hergestellt ist. Durch das Angleichen des thermischen Dehnungsverhaltens des Piezo-Aktuators an den des Injektorgehäuses 1 wird ein gleichbleibendes Schaltverhalten des Piezo-Aktuators im Hinblick auf die Ansteuerung des Schaltventils 10 unterstützt. Durch die hohe Steifigkeit der Manganbasislegierung des thermischen Ausgleichselements 36, die sich insbesondere auszeichnet durch einen hohen Mangananteil, ist gewährleistet, dass bei einem Längen des Stapels 34 der piezoelektrischen Elemente durch die hohe Kraft, die von dem Ventil 10 auch auf das thermische Ausgleichselement 36 einwirkt, nur wenig Nutzhub des Stapels 34 der piezoelektrischen Elemente verloren geht. Somit kann die Ansteue- rung des Stapels 34 der piezoelektrischen Elemente mit einem sehr hohen Wirkungsgrad erfolgen. The thermal compensation element 36 consists of a manganese-copper-nickel alloy, which is referred to below as a manganese-based alloy. The thermal compensating element 36 is preferably made of a block, which is preferably cylindrical in shape of the manganese-based alloy. The manganese base alloy advantageously consists of approximately 72% by weight of manganese, approximately 18% by weight of copper and approximately 10% by weight of nickel. It has a coefficient of thermal expansion of approximately 28 x 10 -6 1 / K in the temperature range from 0 to 200 ° C. The axial length of the thermal compensation element 36 is selected such that the piezo actuator has the same thermal expansion behavior as that Material from which the injector housing 1 is made. By matching the thermal expansion behavior of the piezo actuator to that of the injector housing 1, the switching behavior of the piezo actuator is constant with regard to the control of the switching valve 10 supported. The high stiffness of the manganese base alloy of the thermal compensating element 36, which is characterized in particular by a high manganese content, ensures that when the stack 34 of the piezoelectric elements is lengthened by the high force which also acts on the thermal compensating element 36 from the valve 10 , only a small useful stroke of the stack 34 of the piezoelectric elements is lost. Thus, the control of the stack 34 of the piezoelectric elements can take place with a very high degree of efficiency.

Claims

Patentansprüche claims
1. Einspritzventil - mit einem Injektorgehäuse (1), das eine Ausnehmung (2) aufweist, - mit einem Piezo-Aktuator, der in der Ausnehmung (2) des Injektorgehäuses (1) angeordnet ist und der einen Stapel (34) piezoelektrischer Elemente und ein thermisches Ausgleichselement (36) umfasst, das aus einer Mangan-Kupfer- Nickel-Legierung besteht.1. Injector - with an injector housing (1), which has a recess (2), - with a piezo actuator, which is arranged in the recess (2) of the injector housing (1) and a stack (34) of piezoelectric elements and a thermal compensation element (36), which consists of a manganese-copper-nickel alloy.
2. Einspritzventil nach Anspruch 1, bei dem die Mangan-Kupfer-Nickel-Legierung einen Anteil von etwa 72 Gew-% Mangan, 18 Gew-% Kupfer und 10 Gew-% Nickel aufweist. 2. Injector according to claim 1, wherein the manganese-copper-nickel alloy has a proportion of about 72% by weight of manganese, 18% by weight of copper and 10% by weight of nickel.
PCT/EP2005/051994 2004-06-03 2005-05-02 Injection valve WO2005119049A1 (en)

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DE200410027148 DE102004027148A1 (en) 2004-06-03 2004-06-03 Injector

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WO2008116716A1 (en) * 2007-03-23 2008-10-02 Continental Automotive Gmbh Actuator device having a piezoelectric actuator for an injection valve

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DE102004048395B4 (en) * 2004-10-05 2015-12-10 Continental Automotive Gmbh Piezo injector with contact elements for heat dissipation

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DE19909106A1 (en) * 1999-03-02 2000-09-07 Siemens Ag Temperature compensated actuator unit with piezo element
US6422482B1 (en) * 1998-10-26 2002-07-23 Robert Bosch Gmbh Fuel injection valve
WO2003054378A1 (en) * 2001-12-05 2003-07-03 Robert Bosch Gmbh Fuel injection valve
DE10219149A1 (en) * 2002-04-29 2003-11-20 Siemens Ag Fuel injector has piezoelectric actuator unit in a housing with a different temperature coefficient of expansion to the injector body for temperature compensation
DE10233906A1 (en) * 2002-07-25 2004-02-19 Siemens Ag Fuel injector module, for an IC motor, has a compensation unit linked to the actuator, within a sleeve with heat conductivity in contact with it and the housing to compensate for the housing change through thermal expansion

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Publication number Priority date Publication date Assignee Title
US4284263A (en) * 1978-05-08 1981-08-18 U.S. Philips Corporation Temperature-compensated control valve
US6422482B1 (en) * 1998-10-26 2002-07-23 Robert Bosch Gmbh Fuel injection valve
DE19909106A1 (en) * 1999-03-02 2000-09-07 Siemens Ag Temperature compensated actuator unit with piezo element
WO2003054378A1 (en) * 2001-12-05 2003-07-03 Robert Bosch Gmbh Fuel injection valve
DE10219149A1 (en) * 2002-04-29 2003-11-20 Siemens Ag Fuel injector has piezoelectric actuator unit in a housing with a different temperature coefficient of expansion to the injector body for temperature compensation
DE10233906A1 (en) * 2002-07-25 2004-02-19 Siemens Ag Fuel injector module, for an IC motor, has a compensation unit linked to the actuator, within a sleeve with heat conductivity in contact with it and the housing to compensate for the housing change through thermal expansion

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008116716A1 (en) * 2007-03-23 2008-10-02 Continental Automotive Gmbh Actuator device having a piezoelectric actuator for an injection valve

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