WO2005076378A1 - Piezoelectric actuator comprising an insulating layer - Google Patents

Piezoelectric actuator comprising an insulating layer Download PDF

Info

Publication number
WO2005076378A1
WO2005076378A1 PCT/EP2004/053209 EP2004053209W WO2005076378A1 WO 2005076378 A1 WO2005076378 A1 WO 2005076378A1 EP 2004053209 W EP2004053209 W EP 2004053209W WO 2005076378 A1 WO2005076378 A1 WO 2005076378A1
Authority
WO
WIPO (PCT)
Prior art keywords
sleeve
actuator body
actuator
piezo
sealing material
Prior art date
Application number
PCT/EP2004/053209
Other languages
German (de)
French (fr)
Inventor
Friedrich Boecking
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
Publication of WO2005076378A1 publication Critical patent/WO2005076378A1/en

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/88—Mounts; Supports; Enclosures; Casings
    • H10N30/883—Further insulation means against electrical, physical or chemical damage, e.g. protective coatings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
    • F02M63/0012—Valves
    • F02M63/0014—Valves characterised by the valve actuating means
    • F02M63/0015—Valves characterised by the valve actuating means electrical, e.g. using solenoid
    • F02M63/0026—Valves characterised by the valve actuating means electrical, e.g. using solenoid using piezoelectric or magnetostrictive actuators
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure

Definitions

  • the invention relates to a piezo actuator, in particular for an injection system of a motor vehicle with an actuator body, made of a piezoelectric material that expands and contracts during operation of the actuator body, at least one inner electrode arranged in the actuator body, at least one outer electrode electrically contacting the inner electrode and an insulating layer surrounding the outer electrode ,
  • the invention further relates to the use of such a piezo actuator in an injection system of a motor vehicle.
  • Piezo actuators of the type mentioned above are used, for example, in internal combustion engines as actuators for common rail fuel injection systems and are arranged there within the injection system in a line or chamber, in which liquid fuel is also under, in some cases, considerable pressure.
  • the piezo actuator works as a so-called “wet actuator", whereby its actuator body, which is made up of several layered piezo elements, is surrounded by the liquid fuel.
  • the liquid fuel which is under high pressure, acts in particular on the side surfaces of the actuator body, on its outer electrodes and also between the piezo elements Due to the pressure, which may be up to 1800 bar, the internal electrodes are heavily loaded and may be pushed into the actuator body, so that the contact between the internal electrodes and the external electrode can be destroyed under certain circumstances.
  • Object and solution of the invention are used, for example, in internal combustion engines as actuators for common rail fuel injection systems and are arranged there within the injection system in a line or chamber, in which liquid fuel is also under, in some cases, considerable pressure.
  • the invention is based on the object of providing a piezo actuator of the type mentioned at the beginning, in which damage to the coupling between the outer electrode and inner electrodes by the fuel, which surrounds the associated actuator body and is under high pressure, is reliably prevented.
  • a piezo actuator according to the preamble of claim 1, in which a sleeve is provided which at least partially directly surrounds the actuator body and the insulating layer. Furthermore, the assignments are through
  • an additional component in the form of a sleeve is provided on a piezo actuator, which is designed and arranged in such a way that it specifically absorbs and discharges the pressure of the fuel that surrounds the actuator body.
  • the insulating layer must first electrically isolate the outer electrodes and seal the actuator body from the surrounding fuel. Furthermore, the insulating layer must transfer heat from the actuator body to the liquid fuel, and finally the insulating layer, as a third function, must also absorb the pressure that is exerted on the actuator body by the surrounding fuel.
  • the function of the power transmission is assigned in particular to a sleeve provided specifically for this purpose, which at least partially directly surrounds the actuator body and the insulating layer.
  • the force directed by the liquid fuel onto the actuator body is intercepted by the sleeve according to the invention without the insulating layer underneath in particular having to absorb this force.
  • the sleeve according to the invention is advantageously provided over the entire height of the actuator body so that, in the case of a cylindrical, in particular cuboid or circular, cylindrical actuator body, the internal electrodes arranged therein are protected overall from the comparatively high pressure of the surrounding fuel.
  • the insulating layer can then be introduced comparatively easily between the actuator body and the sleeve during the manufacture of the piezo actuator 2, for example by a spraying process.
  • a sealing element which seals between the sleeve and the actuator body, is provided on the end regions of the sleeve.
  • a sealing element specifically takes over the function of the fuel seal, so that the sleeve, together with the sealing material, forms a type of capsule on the actuator body, under which the inner electrodes, the outer electrodes and optionally also the insulating layer are then arranged.
  • the sealing material provided according to the invention can also alone form a type of capsule around the actuator body and its inner and outer electrodes by forming the sealing material along the inside of the sleeve, in particular in a layer running between the sleeve and the insulating layer.
  • a solution with an encapsulating sealing material is also advantageous, in which the sealing material extends along the outside of the actuator body, in particular in a layer running between the insulating layer and the actuator body.
  • the sealing material finally extends along the outside of the sleeve, in particular in a layer surrounding the sleeve. Sealing material designed in this way completely takes over the function of the fuel seal, while the sleeve underneath takes over the power transmission and finally the function of heat conduction is assigned to the insulation layer arranged between the sleeve and the actuator body.
  • a clear separation of functions is thus created, so that the individual components of such a piezo actuator can be specifically adapted to the functions assigned to them.
  • Such a simple separation of functions to represent a “wet actuator” is particularly advantageous for “common rail injection systems” on which the fuel surrounding the actuator body is under a comparatively high pressure.
  • FIG. 1 shows a partial longitudinal section of a first exemplary embodiment of a piezo actuator according to the invention
  • FIG. 2 shows a partial longitudinal section of a second exemplary embodiment of a piezo actuator according to the invention
  • 3 shows a partial longitudinal section of a third exemplary embodiment of a piezo actuator according to the invention
  • FIG. 4 shows a partial longitudinal section of a fourth exemplary embodiment of a piezo actuator according to the invention
  • FIG. 5 shows a partial longitudinal section of a fifth exemplary embodiment of a piezo actuator according to the invention.
  • FIG. 1 shows a first exemplary embodiment of a piezo actuator 10 which, as an essential component, comprises a cylindrical actuator body 12 with an actuator head 14 arranged on its end face.
  • the actuator body 12 is constructed from a plurality of layered piezo elements 16, between which there are essentially thin, disk-shaped inner electrodes 18.
  • the inner electrodes are alternately connected to outer electrodes, of which one outer electrode 20 is shown in FIG.
  • the outer electrodes 20 are each in the form of a longitudinal strip on the lateral or side surfaces of the actuator body 20 and serve to make electrical contact with the inner electrodes 18.
  • the outer electrodes 20 and also the jacket or side surfaces of the actuator body 12 are surrounded by an insulation layer 22, which is to perform the following three functions in known piezo actuators:
  • the insulation layer is intended to produce a heat-conducting connection between the actuator body and its surroundings. It is also intended to seal off the actuator body and the internal electrodes therein from this environment and in particular from a liquid fuel located there, and finally the insulation layer should also absorb the force determined by the under Operating conditions high pressure of this liquid fuel is exerted on the actuator body and its internal electrodes.
  • this third function of known insulation layers is transferred to its own additional component, namely to a thin-walled sleeve 24 which directly surrounds the actuator body 12 and the associated insulation layer 22 over the entire height of the actuator body 12.
  • the sleeve 24 thus absorbs that pressure force that is exerted by a liquid fuel surrounding the piezo actuator 10 and under high pressure.
  • the sleeve 24 protects the underlying insulation layer 22 and the outer electrodes 20, the inner electrodes
  • FIG. 2 shows an exemplary embodiment of a piezo actuator 10, in which the function of the fuel seal between the surroundings of the actuator body 12 and its internal electrodes 18 is also taken over by a separate component.
  • This separate component is a sealing material 26 which is injected at the upper end region of the sleeve 24 between this sleeve 24 and the actuator head 14 adjacent there. Under the sealing material 26 there is in a conventional manner the insulation layer 22 which, as in the exemplary embodiment according to FIG. 1, is injected between the sleeve 24 and the actuator body 12.
  • FIGS. 3 to 5 show exemplary embodiments of piezo actuators 10, in which the inner electrodes 18 are completely encapsulated with respect to the surroundings of the actuator body 12 with the aid of the sealing material 26.
  • the sealing material 26 is in turn injected at the end regions of the sleeve 24 between this sleeve 24 and the respectively adjacent actuator head 14.
  • a sealing material layer 28 is also provided, which is based on the sealing material injected on the actuator head 14 26 extends between the insulation layer 22 arranged within the sleeve 24 and the actuator body 12.
  • the sealing material layer 28 extends from that arranged on the actuator head 14
  • the sealing material layer 28 is finally arranged on the outside of the sleeve 24.
  • the sealing material layer 28 according to FIG. 5 extends along the sleeve 24 to the sealing material 26, which is arranged at the end of the sleeve 24 between the actuator head 14 and the sleeve 24 and furthermore which also comprises the end of the sleeve 24 itself.

Abstract

The invention relates to a piezoelectric actuator (10) especially for an injection system of a motor vehicle. Said actuator comprises a body (12) consisting of a piezoelectric material that expands and contracts during the operation of the actuator body (12), at least one inner electrode (18) arranged in the actuator body (12), at least one outer electrode (20) electrically contacting the inner electrode (18), and an insulating layer (22) surrounding the outer electrode (20). According to the invention, a sleeve (24) at least partially directly surrounds the actuator body (12) and the insulating layer (22).

Description

Piezoaktor mit einer IsolierschichtPiezo actuator with an insulating layer
Stand der TechnikState of the art
Die Erfindung betrifft einen Piezoaktor, insbesondere für ein Einspritzsystem eines Kraftfahrzeuges mit einem Aktorkörper, aus einem piezoelektrischen Material, welches im Betrieb des Aktorkörpers expandiert und kontrahiert, mindestens einer im Aktorkörper angeordneten Innenelektrode, mindestens einer die Innenelektrode elektrisch kontaktierenden Außenelektrode und einer die Außenelektrode umgebenden Isolierschicht. Ferner betrifft die Erfindung die Verwendung eines solchen Piezoaktors in einem Einspritzsystem eines Kraftfahrzeugs.The invention relates to a piezo actuator, in particular for an injection system of a motor vehicle with an actuator body, made of a piezoelectric material that expands and contracts during operation of the actuator body, at least one inner electrode arranged in the actuator body, at least one outer electrode electrically contacting the inner electrode and an insulating layer surrounding the outer electrode , The invention further relates to the use of such a piezo actuator in an injection system of a motor vehicle.
Piezoaktoren der oben genannten Bauart werden beispielsweise bei Brennkraftmaschinen als Stellglied für Common-Rail-Kraftstoffeinspritzsysteme verwendet und sind dort innerhalb des Einspritzsystems in einer Leitung oder Kammer angeordnet, in der sich ferner flüssiger Brennstoff unter teilweise erheblichem Druck befindet. Der Piezoaktor arbeitet als so genannter „nasser Aktor", wobei sein aus mehreren geschichteten Piezoelementen aufgebauter Aktorkörper vom flüssigen Brennstoff umgeben ist. Der unter hohem Druck stehende flüssige Brennstoff wirkt insbesondere auf die Seitenflächen des Aktorkörpers, auf dessen Außenelektroden und auch die sich zwischen den Piezoelementen befindenden Innelektroden ein. Durch den unter Umständen bis zu 1800 bar hohen Druck werden die Innenelektroden stark belastet und unter Umständen in den Aktorkörper hinein gedrängt, sodass die Kontaktierung der Innenelektroden zur Außenelektrode unter Umständen zerstört werden kann. Aufgabe und Lösung der ErfindungPiezo actuators of the type mentioned above are used, for example, in internal combustion engines as actuators for common rail fuel injection systems and are arranged there within the injection system in a line or chamber, in which liquid fuel is also under, in some cases, considerable pressure. The piezo actuator works as a so-called "wet actuator", whereby its actuator body, which is made up of several layered piezo elements, is surrounded by the liquid fuel. The liquid fuel, which is under high pressure, acts in particular on the side surfaces of the actuator body, on its outer electrodes and also between the piezo elements Due to the pressure, which may be up to 1800 bar, the internal electrodes are heavily loaded and may be pushed into the actuator body, so that the contact between the internal electrodes and the external electrode can be destroyed under certain circumstances. Object and solution of the invention
Der Erfindung liegt die Aufgäbe zugrunde, einen Piezoaktor der eingangs genannten Art bereitzustellen, bei dem eine Beschädigung der Kopplung zwischen Außenelektrode und Innenelektroden durch den Brennstoff, welcher den zugehörigen Aktorkörper umgibt und unter hohem Druck steht, sicher verhindert ist.The invention is based on the object of providing a piezo actuator of the type mentioned at the beginning, in which damage to the coupling between the outer electrode and inner electrodes by the fuel, which surrounds the associated actuator body and is under high pressure, is reliably prevented.
Die Aufgäbe ist erfindungsgemäß durch einen Piezoaktor gemäß dem Oberbegriff des Anspruchs 1 gelöst, bei dem eine Hülse vorgesehen ist, die den Aktorkörper und die Isolierschicht zumindest teilweise unmittelbar umgibt. Ferner ist die Aufgäbe durchThe task is solved according to the invention by a piezo actuator according to the preamble of claim 1, in which a sleeve is provided which at least partially directly surrounds the actuator body and the insulating layer. Furthermore, the assignments are through
Verwendung eines derartigen erfindungsgemäßen Piezoaktors in einem Einspritzsystem eines Kraftfahrzeugs gelöst.Using such a piezo actuator according to the invention in an injection system of a motor vehicle solved.
Erfindungsgemäß ist an einem Piezoaktor ein zusätzliches Bauteil in Gestalt einer Hülse vorgesehen, die derart gestaltet und angeordnet ist, dass sie gezielt den Druck des Kraftstoffes aufnimmt und ableitet, der den Aktorkörper umgibt.According to the invention, an additional component in the form of a sleeve is provided on a piezo actuator, which is designed and arranged in such a way that it specifically absorbs and discharges the pressure of the fuel that surrounds the actuator body.
Bei bekannten Piezoaktoren ist im Gegensatz zu dieser erfindungsgemäßen Lösung am Aktorkörper lediglich eine Isolierschicht vorgesehen, die den Aktorkörper und dessen Außenelektroden umgibt und die insgesamt drei Funktionen übernehmen uss.In known piezo actuators, in contrast to this solution according to the invention, only an insulating layer is provided on the actuator body, which surrounds the actuator body and its outer electrodes and which perform a total of three functions, etc.
Die Isolierschicht muss zunächst die Außenelektroden elektrisch isolieren und den Aktorkörper gegenüber dem umgebenden Brennstoff abdichten. Ferner muss die Isolierschicht Wärme vom Aktorkörper auf den flüssigen Brennstoff überleiten und schließlich muss die Isolierschicht als dritte Funktion noch jenen Druck aufnehmen, der vom umgebenden Brennstoff auf den Aktorkörper ausgeübt wird.The insulating layer must first electrically isolate the outer electrodes and seal the actuator body from the surrounding fuel. Furthermore, the insulating layer must transfer heat from the actuator body to the liquid fuel, and finally the insulating layer, as a third function, must also absorb the pressure that is exerted on the actuator body by the surrounding fuel.
Eine Isolierschicht vorzusehen, die all diesen Funktionen in hervorragender Weise gerecht wird, ist ein sehr schwieriges, wenn nicht nahezu unmögliches Unterfangen. Erfindungsgemäß werden die oben genannten Funktionen hingegen getrennt und auf mehrere Bauteile verteilt. Die sehr schwierige Kombination aus Wärmeleitung, Kraftstoffabdichtung und Kraftübertragung in nur einem Bauelement bzw. einer Isolierschicht ist dadurch erfindungsgemäß vermieden.Providing an insulating layer that excellently fulfills all of these functions is a very difficult, if not nearly impossible, undertaking. According to the invention, however, the functions mentioned above are separated and distributed over several components. The very difficult combination of heat conduction, fuel sealing and power transmission in only one component or an insulating layer is avoided according to the invention.
Gemäß der Erfindung wird insbesondere die Funktion der Kraftübertragung einer eigens dafür vorgesehenen Hülse zugeordnet, die den Aktorkörper und die Isolierschicht zumindest teilweise unmittelbar umgibt. Die vom flüssigen Brennstoff auf den Aktorkörper geleitete Kraft wird durch die erfindungsgemäße Hülse abgefangen, ohne dass insbesondere die darunter liegende Isolierschicht diese Kraft aufnehmen müsste.According to the invention, the function of the power transmission is assigned in particular to a sleeve provided specifically for this purpose, which at least partially directly surrounds the actuator body and the insulating layer. The force directed by the liquid fuel onto the actuator body is intercepted by the sleeve according to the invention without the insulating layer underneath in particular having to absorb this force.
Damit bei einem zylindrischen, insbesondere quaderförmigen oder kreiszylindrischen Aktorkörper die darin angeordneten Innenelektroden insgesamt vor dem vergleichsweise hohen Druck des umgebenden Brennstoffs geschützt sind, ist die erfindungsgemäße Hülse vorteilhaft über die gesamte Höhe des Aktorkörpers hinweg vorgesehen.The sleeve according to the invention is advantageously provided over the entire height of the actuator body so that, in the case of a cylindrical, in particular cuboid or circular, cylindrical actuator body, the internal electrodes arranged therein are protected overall from the comparatively high pressure of the surrounding fuel.
Ferner ist es bei einem derartigen Aktorkörper sinnvoll, wenn die Hülse, die den Aktorkörper umgebende Isolierschicht an deren Seitenfläche bzw. Mantelfläche • vollständig umschließt. Die Isolierschicht kann dann bei der Herstellung des Piezoaktors 2wischen dem Aktorkörper und der Hülse beispielsweise durch einen Spritzprozess vergleichsweise leicht eingebracht werden.Further, it is useful in such an actuator body when the sleeve which completely surrounds the actuator body surrounding insulating layer on the side surface or circumferential surface •. The insulating layer can then be introduced comparatively easily between the actuator body and the sleeve during the manufacture of the piezo actuator 2, for example by a spraying process.
Um eine weitere Trennung der oben genannten Funktionen auf mehrere Bauelemente zu erreichen, ist es bei dem erfϊndungsgemäßen Piezoaktor ferner von Vorteil, wenn an den Endbereichen der Hülse ein zwischen der Hülse und dem Aktorkörper fluiddicht abdichtendes Dichtelement vorgesehen ist. Ein solches Dichtelement übernimmt gezielt die Funktion der Kraftstoffabdichtung, sodass die Hülse zusammen mit dem Dichtmaterial eine Art Kapsel am Aktorkörper bildet, unter der dann die Innenelektroden, die Außenelektroden und gegebenenfalls auch die Isolierschicht angeordnet sind. Das erfϊndungsgemäß vorgesehene Dichtmaterial kann auch allein eine Art Kapsel um den Aktorkörper herum und dessen Innen- sowie Außenelektroden herum bilden, indem das Dichtmaterial entlang der Innenseite der Hülse, insbesondere in einer zwischen der Hülse und der Isolierschicht verlaufenden Schicht ausgebildet ist.In order to achieve a further separation of the above-mentioned functions into a number of components, it is also advantageous in the piezo actuator according to the invention if a sealing element, which seals between the sleeve and the actuator body, is provided on the end regions of the sleeve. Such a sealing element specifically takes over the function of the fuel seal, so that the sleeve, together with the sealing material, forms a type of capsule on the actuator body, under which the inner electrodes, the outer electrodes and optionally also the insulating layer are then arranged. The sealing material provided according to the invention can also alone form a type of capsule around the actuator body and its inner and outer electrodes by forming the sealing material along the inside of the sleeve, in particular in a layer running between the sleeve and the insulating layer.
Vorteilhaft ist ferner eine Lösung mit einem kapselnden Dichtmaterial, bei der sich das Dichtmaterial entlang der Außenseite des Aktorkörpers, insbesondere in einer zwischen der Isolierschicht und dem Aktorkörper verlaufenden Schicht erstreckt.A solution with an encapsulating sealing material is also advantageous, in which the sealing material extends along the outside of the actuator body, in particular in a layer running between the insulating layer and the actuator body.
Bei einer dritten möglichen Variante erstreckt sich das Dichtmaterial schließlich entlang der Außenseite der Hülse, insbesondere in einer die Hülse umschließenden Schicht. Derart ausgebildetes Dichtmaterial übernimmt vollständig die Funktion der Kraftstoffäbdichtung, während die darunter liegende Hülse die Kraftübertragung übernimmt und schließlich der zwischen der Hülse und dem Aktorkörper angeordneten Isolationsschicht die Funktion der Wärmeleitung zugeordnet ist. Es ist also eine klare Funktionstrennung geschaffen, sodass die einzelnen Bauelemente eines derartigen Piezoaktors gezielt auf die ihnen zugewiesenen Funktionen angepasst sein können. Eine solche einfache Funktionstrennung zur Darstellung eines „nassen Aktors" ist insbesondere für „Common-Rail-Einspritzsysteme" vorteilhaft, an denen der den Aktorkörper umgebende Brennstoff unter einem vergleichsweise hohen Druck steht.In a third possible variant, the sealing material finally extends along the outside of the sleeve, in particular in a layer surrounding the sleeve. Sealing material designed in this way completely takes over the function of the fuel seal, while the sleeve underneath takes over the power transmission and finally the function of heat conduction is assigned to the insulation layer arranged between the sleeve and the actuator body. A clear separation of functions is thus created, so that the individual components of such a piezo actuator can be specifically adapted to the functions assigned to them. Such a simple separation of functions to represent a “wet actuator” is particularly advantageous for “common rail injection systems” on which the fuel surrounding the actuator body is under a comparatively high pressure.
Kurzbeschreibung der ZeichnungenBrief description of the drawings
Nachfolgend werden Ausführungsbeispiele erfindungsgemäßer Piezoaktoren anhand der beigefügten schematischen Zeichnungen näher erläutert. Es zeigt:Exemplary embodiments of piezo actuators according to the invention are explained in more detail below with reference to the attached schematic drawings. It shows:
Fig. 1 einen teilweisen Längsschnitt eines ersten Ausführungsbeispiels eines erfindungsgemäßen Piezoaktors, Fig. 2 einen teilweisen Längsschnitt eines zweiten Ausfuhrungsbeispiels eines erfindungsgemäßen Piezoaktors, Fig. 3 einen teilweisen Längsschnitt eines dritten Ausführungsbeispiels eines erfindungsgemäßen Piezoaktors, Fig.4 einen teilweisen Längsschnitt eines vierten Ausfuhrungsbeispiels eines erfindungsgemäßen Piezoaktors und Fig. 5 einen teilweisen Längsschnitt eines fünften Ausführungsbeispiels eines erfindungsgemäßen Piezoaktors.1 shows a partial longitudinal section of a first exemplary embodiment of a piezo actuator according to the invention, FIG. 2 shows a partial longitudinal section of a second exemplary embodiment of a piezo actuator according to the invention, 3 shows a partial longitudinal section of a third exemplary embodiment of a piezo actuator according to the invention, FIG. 4 shows a partial longitudinal section of a fourth exemplary embodiment of a piezo actuator according to the invention, and FIG. 5 shows a partial longitudinal section of a fifth exemplary embodiment of a piezo actuator according to the invention.
Detaillierte Beschreibung der AusführungsbeispieleDetailed description of the exemplary embodiments
In Figur 1 ist ein erstes Ausführungsbeispiel eines Piezoaktors 10 dargestellt, der als ein wesentliches Bauelement einen zylindrischen Aktorkörper 12 mit einem an dessen Stirnseite angeordneten Aktorkopf 14 umfasst. Der Aktorkörper 12 ist aus mehreren geschichteten Piezoelementen 16 aufgebaut, zwischen denen sich im Wesentlichen dünne, scheibenförmige Innenelektroden 18 befinden. Die Innenelektroden sind jeweils wechselweise an Außenelektroden angeschlossen, von denen in Figur 1 eine Außenelektrode 20 dargestellt ist.FIG. 1 shows a first exemplary embodiment of a piezo actuator 10 which, as an essential component, comprises a cylindrical actuator body 12 with an actuator head 14 arranged on its end face. The actuator body 12 is constructed from a plurality of layered piezo elements 16, between which there are essentially thin, disk-shaped inner electrodes 18. The inner electrodes are alternately connected to outer electrodes, of which one outer electrode 20 is shown in FIG.
Die Außenelektroden 20 befinden sich jeweils in Gestalt eines Längsstreifens an den Mantel- bzw. Seitenflächen des Aktorkörper 20 und dienen zur elektrischen Kontaktierung der Innenelektroden 18.The outer electrodes 20 are each in the form of a longitudinal strip on the lateral or side surfaces of the actuator body 20 and serve to make electrical contact with the inner electrodes 18.
Die Außenelektroden 20 und auch die Mantel- bzw. Seitenflächen des Aktorkörpers 12 sind von einer Isolationsschicht 22 umgeben, die bei bekannten Piezoaktoren die folgenden drei Funktionen übernehmen soll:The outer electrodes 20 and also the jacket or side surfaces of the actuator body 12 are surrounded by an insulation layer 22, which is to perform the following three functions in known piezo actuators:
Die Isolationsschicht soll zum einen eine wärmeleitende Verbindung zwischen dem Aktorkörper und dessen Umgebung herstellen. Sie soll ferner gegenüber dieser Umgebung und insbesondere gegenüber einem sich dort befindenden flüssigen Brennstoff den Aktorkörper und die darin befindlichen Innenelektroden abdichten und schließlich soll die Isolationsschicht auch jene Kraft aufnehmen, die durch den unter bestimmten Betriebszuständen hohen Druck dieses flüssigen Brennstoffs auf den Aktorkörper und dessen Innenelektroden ausgeübt wird.On the one hand, the insulation layer is intended to produce a heat-conducting connection between the actuator body and its surroundings. It is also intended to seal off the actuator body and the internal electrodes therein from this environment and in particular from a liquid fuel located there, and finally the insulation layer should also absorb the force determined by the under Operating conditions high pressure of this liquid fuel is exerted on the actuator body and its internal electrodes.
Bei dem bei in Figur 1 dargestellten Piezoaktor 10 ist diese dritte Funktion bekannter Isolationsschichten auf ein eigenes, zusätzliches Bauteil übertragen, nämlich auf eine dünnwandige Hülse 24, die den Aktorkörper 12 und die zugehörige Isolationsschicht 22 über die gesamte Höhe des Aktorkörpers 12 hinweg unmittelbar umgibt. Die Hülse 24 nimmt damit jene Druckkraft auf, die von einem den Piezoaktor 10 umgebenden und unter hohem Druck stehenden flüssigen Brennstoff ausgeübt wird. Die Hülse 24 schützt die darunter liegenden Isolationsschicht 22 sowie die Außenelektroden 20, die InnenelektrodenIn the piezo actuator 10 shown in FIG. 1, this third function of known insulation layers is transferred to its own additional component, namely to a thin-walled sleeve 24 which directly surrounds the actuator body 12 and the associated insulation layer 22 over the entire height of the actuator body 12. The sleeve 24 thus absorbs that pressure force that is exerted by a liquid fuel surrounding the piezo actuator 10 and under high pressure. The sleeve 24 protects the underlying insulation layer 22 and the outer electrodes 20, the inner electrodes
18 und die Piezoelemente 16 des Aktorkörpers 12 insgesamt vor einer möglichen mechanischen Beschädigung.18 and the piezo elements 16 of the actuator body 12 as a whole from possible mechanical damage.
In Figur 2 ist ein Ausfuhrungsbeispiel eines Piezoaktors 10 veranschaulicht, bei dem auch die Funktion der Kraftstoffabdichtung zwischen der Umgebung des Aktorkörpers 12 und dessen Innenelektroden 18 von einem separaten Bauelement übernommen wird. Dieses separate Bauelement ist ein Dichtmaterial 26, welches am oberen Endbereich der Hülse 24 zwischen dieser Hülse 24 und dem dort benachbarten Aktorkopf 14 eingespritzt ist. Unter dem Dichtmaterial 26 befindet sich in herkömmlicher Weise die Isolationsschicht 22, die, wie bei dem Ausführungsbeispiel gemäß Figur 1, zwischen der Hülse 24 und dem Aktorkörper 12 eingespritzt ist.FIG. 2 shows an exemplary embodiment of a piezo actuator 10, in which the function of the fuel seal between the surroundings of the actuator body 12 and its internal electrodes 18 is also taken over by a separate component. This separate component is a sealing material 26 which is injected at the upper end region of the sleeve 24 between this sleeve 24 and the actuator head 14 adjacent there. Under the sealing material 26 there is in a conventional manner the insulation layer 22 which, as in the exemplary embodiment according to FIG. 1, is injected between the sleeve 24 and the actuator body 12.
In den Figuren 3 bis 5 sind Ausfuhrungsbeispiele von Piezoaktoren 10 dargestellt, bei denen mit Hilfe des Dichtmaterials 26 die Innenelektroden 18 gegenüber der Umgebung des Aktorkörpers 12 vollständig gekapselt sind. Das Dichtmaterial 26 ist dazu jeweils wiederum an den Endbereichen der Hülse 24 zwischen dieser Hülse 24 und dem jeweils benachbarten Aktorkopf 14 eingespritzt.FIGS. 3 to 5 show exemplary embodiments of piezo actuators 10, in which the inner electrodes 18 are completely encapsulated with respect to the surroundings of the actuator body 12 with the aid of the sealing material 26. For this purpose, the sealing material 26 is in turn injected at the end regions of the sleeve 24 between this sleeve 24 and the respectively adjacent actuator head 14.
Bei dem in Figur 3 dargestellten Ausführungsbeispiel ist ferner eine Dichtmaterial-Schicht 28 vorgesehen, die sich ausgehend von dem am Aktorkopf 14 eingespritzten Dichtmaterial 26 zwischen der innerhalb der Hülse 24 angeordneten Isolationsschicht 22 und dem Aktorkörper 12 erstreckt.In the exemplary embodiment shown in FIG. 3, a sealing material layer 28 is also provided, which is based on the sealing material injected on the actuator head 14 26 extends between the insulation layer 22 arranged within the sleeve 24 and the actuator body 12.
Bei dem in Figur 4 veranschaulichten Ausführungsbeispiel erstreckt sich die Dichtmaterial-Schicht 28 ausgehend von dem am Aktorkopf 14 angeordnetenIn the exemplary embodiment illustrated in FIG. 4, the sealing material layer 28 extends from that arranged on the actuator head 14
Dichtmaterial 26 zwischen der Hülse 24 und der am Aktorkörper 12 angeordneten Isolationsschicht 22.Sealing material 26 between the sleeve 24 and the insulation layer 22 arranged on the actuator body 12.
Bei dem in Figur 5 veranschaulichten Ausführungsbeispiel eines Piezoaktors 10 ist die Dichtmaterial-Schicht 28 schließlich an der Außenseite der Hülse 24 angeordnet. DieIn the exemplary embodiment of a piezo actuator 10 illustrated in FIG. 5, the sealing material layer 28 is finally arranged on the outside of the sleeve 24. The
Dichtmaterial-Schicht 28 gemäß Figur 5 erstreckt sich entlang der Hülse 24 bis zum Dichtmaterial 26, welches am Ende der Hülse 24 zwischen dem Aktorkopf 14 und der Hülse 24 angeordnet ist und femer welches femer das Ende der Hülse 24 selbst umfasst. The sealing material layer 28 according to FIG. 5 extends along the sleeve 24 to the sealing material 26, which is arranged at the end of the sleeve 24 between the actuator head 14 and the sleeve 24 and furthermore which also comprises the end of the sleeve 24 itself.

Claims

Ansprüche Expectations
1. Piezoaktor (10), insbesondere für ein Einspritzsystem eines Kraftfahrzeugs, mit einem Aktorkörper (12) aus einem piezoelektrischen Material, welches im Betrieb des Aktorkörpers (12) expandiert und kontrahiert, mindestens einer im AJktorkörper (12) angeordneten Innenelektrode (18), mindestens einer die Innenelektrode (18) elektrisch kontaktierenden Außenelektrode (20) und einer die Außenelektrode (20) umgebenden Isolationsschicht (22), dadurch gekennzeichnet, dass eine Hülse (24) vorgesehen ist, die den Aktorkörper (12) und die Isolationsschicht (22) zumindest teilweise unmittelbar umgibt.1. Piezo actuator (10), in particular for an injection system of a motor vehicle, with an actuator body (12) made of a piezoelectric material, which expands and contracts during operation of the actuator body (12), at least one inner electrode (18) arranged in the actuator body (12), at least one outer electrode (20) electrically contacting the inner electrode (18) and an insulation layer (22) surrounding the outer electrode (20), characterized in that a sleeve (24) is provided which covers the actuator body (12) and the insulation layer (22) at least partially surrounds directly.
2. Piezoaktor nach Anspruch 1 , dadurch gekennzeichnet, dass der Aktorkörper (12) zylindrisch, insbesondere quaderförmig oder kreiszylindrisch gestaltet ist und die Hülse (24) sich im Wesentlichen über die gesamte Höhe des Aktorkörpers (12) erstreckt.2. Piezo actuator according to claim 1, characterized in that the actuator body (12) is cylindrical, in particular cuboid or circular cylindrical, and the sleeve (24) extends essentially over the entire height of the actuator body (12).
3. Piezoaktor nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass der Aktorkörper (12) zylindrisch, insbesondere quaderförmig oder kreiszylindrisch gestaltet ist, die Isolationsschicht (22) den Aktorkörper (12) an dessen Seitenflächen umgibt und die Hülse (24) ihrerseits die Isolationsschicht (22) an deren Seitenfläche vollständig umschließt. 3. Piezo actuator according to claim 1 or 2, characterized in that the actuator body (12) is cylindrical, in particular cuboid or circular cylindrical, the insulation layer (22) surrounds the actuator body (12) on its side faces and the sleeve (24) in turn the insulation layer (22) completely encloses on the side surface.
4. Piezoaktor nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass an mindestens einem der Endbereiche der Hülse (24) ein zwischen der Hülse (24) und dem Aktorkörper (12) fluiddicht abdichtendes Dichtmaterial (26) vorgesehen ist.4. Piezo actuator according to one of claims 1 to 3, characterized in that a sealing material (26) sealing in a fluid-tight manner between the sleeve (24) and the actuator body (12) is provided on at least one of the end regions of the sleeve (24).
5. Piezoaktor nach Anspruch 4, dadurch gekennzeichnet, dass das Dichtmaterial (26) sich entlang der Innenseite der Hülse (24), insbesondere in einer zwischen der Hülse (24) und der Isolationsschicht (22) verlaufenden Schicht (28) erstreckt.5. Piezo actuator according to claim 4, characterized in that the sealing material (26) extends along the inside of the sleeve (24), in particular in a layer (28) extending between the sleeve (24) and the insulation layer (22).
6. Piezoaktor nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass das Dichtmaterial (26) sich entlang der Außenseite des Aktorkörpers (12), insbesondere in einer zwischen der Isolationsschicht (22) und dem Aktorkörper (12) verlaufenden Schicht (28) erstreckt.6. Piezo actuator according to claim 4 or 5, characterized in that the sealing material (26) extends along the outside of the actuator body (12), in particular in a layer (28) extending between the insulation layer (22) and the actuator body (12).
7. Piezoaktor nach einem der Ansprüche 4 bis 6, dadurch gekennzeichnet, dass das Dichtmaterial (26) sich entlang der Außenseite der Hülse (24), insbesondere in einer die Hülse (24) umschließenden Schicht (28) erstreckt.7. Piezo actuator according to one of claims 4 to 6, characterized in that the sealing material (26) extends along the outside of the sleeve (24), in particular in a layer (28) surrounding the sleeve (24).
8. Verwendung eines Piezoaktors (10) gemäß einem der Ansprüche 1 bis 7 in einem Einspritzsystem eines Kraftfahrzeugs. 8. Use of a piezo actuator (10) according to one of claims 1 to 7 in an injection system of a motor vehicle.
PCT/EP2004/053209 2004-02-03 2004-12-01 Piezoelectric actuator comprising an insulating layer WO2005076378A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102004005226.3 2004-02-03
DE102004005226A DE102004005226A1 (en) 2004-02-03 2004-02-03 Piezo actuator with an insulating layer

Publications (1)

Publication Number Publication Date
WO2005076378A1 true WO2005076378A1 (en) 2005-08-18

Family

ID=34801481

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2004/053209 WO2005076378A1 (en) 2004-02-03 2004-12-01 Piezoelectric actuator comprising an insulating layer

Country Status (2)

Country Link
DE (1) DE102004005226A1 (en)
WO (1) WO2005076378A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007015457A1 (en) * 2007-03-30 2008-10-02 Siemens Ag Piezoelectric component with security layer and method for its production

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010061946A1 (en) * 2010-11-25 2012-05-31 Robert Bosch Gmbh Piezoelectric actuator module and fuel injection valve

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19818068A1 (en) * 1998-04-22 1999-10-28 Siemens Ag Piezo-electronic actuator for an actuator
DE19860001A1 (en) * 1998-12-23 2000-07-06 Siemens Ag Piezoelectric component, especially for controlling an internal combustion engine injection valve, has electrically insulating material-containing interspaces between its piezoceramic layers
DE10054017A1 (en) * 2000-11-01 2002-05-08 Bosch Gmbh Robert Piezo-actuator module, especially for fuel injection system, has sheath element designed as heat-conducting rubber element which has shell-shaped design and lies directly on piezo-actuator
US20020084350A1 (en) * 2000-12-28 2002-07-04 Naoyuki Kawazoe Piezoelectric device for injector, method for producing the same, and injector
DE10225408A1 (en) * 2002-06-07 2003-12-24 Epcos Ag Piezoactuator has envelope under mechanical tension molded at least partly around its surface, so that end pieces are pressed against bottom and top surfaces by envelope
DE10231624A1 (en) * 2002-07-12 2004-01-29 Robert Bosch Gmbh Piezoelectric component

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19818068A1 (en) * 1998-04-22 1999-10-28 Siemens Ag Piezo-electronic actuator for an actuator
DE19860001A1 (en) * 1998-12-23 2000-07-06 Siemens Ag Piezoelectric component, especially for controlling an internal combustion engine injection valve, has electrically insulating material-containing interspaces between its piezoceramic layers
DE10054017A1 (en) * 2000-11-01 2002-05-08 Bosch Gmbh Robert Piezo-actuator module, especially for fuel injection system, has sheath element designed as heat-conducting rubber element which has shell-shaped design and lies directly on piezo-actuator
US20020084350A1 (en) * 2000-12-28 2002-07-04 Naoyuki Kawazoe Piezoelectric device for injector, method for producing the same, and injector
DE10225408A1 (en) * 2002-06-07 2003-12-24 Epcos Ag Piezoactuator has envelope under mechanical tension molded at least partly around its surface, so that end pieces are pressed against bottom and top surfaces by envelope
DE10231624A1 (en) * 2002-07-12 2004-01-29 Robert Bosch Gmbh Piezoelectric component

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007015457A1 (en) * 2007-03-30 2008-10-02 Siemens Ag Piezoelectric component with security layer and method for its production
DE102007015457B4 (en) * 2007-03-30 2009-07-09 Siemens Ag Piezoelectric device with security layer, process for its production and use
US8492955B2 (en) 2007-03-30 2013-07-23 Siemens Aktiengesellschaft Piezoelectric component comprising security layer and method for the production thereof

Also Published As

Publication number Publication date
DE102004005226A1 (en) 2005-08-18

Similar Documents

Publication Publication Date Title
EP1485607B1 (en) Sealing element for the piezo actuator of a fuel injection valve
EP1901360B1 (en) Piezo actuator module with a cladded piezo actuator
EP1906464A1 (en) Piezo actuator with a jacket for placing in a piezo injector
EP3428443B1 (en) Press-in sleeve for a cylinder head
EP2080238A1 (en) Actuator module comprising an enveloped piezoactuator
EP1628015B1 (en) Sealing arrangement of a piezo actuator of a fuel injector
EP2018672B1 (en) Injector comrising a piezoelectric actuator for an internal combustion engine
DE102006025820A1 (en) Piezoelectric actuator for use in fuel injector, has casing made of composite materials and comprising two layers, where layers are made of metallic substance and polymer, respectively and are arranged in sections
WO2005076378A1 (en) Piezoelectric actuator comprising an insulating layer
WO2006018399A1 (en) Actuator for a fuel injector in an internal combustion engine and use therefor
DE102006006076B4 (en) Piezo actuator, method for producing a piezo actuator and injection system with such
WO2004047191A2 (en) Piezo actuator contact mechanism for an injection valve and method for producing said actuator
EP1909339B1 (en) Actuator module having an enshrouded piezo actuator
EP2636081B1 (en) Actuator unit and method for producing thereof
EP3036431B1 (en) Piezo actuator for a fuel injector, and fuel injector
EP1912265B1 (en) Actuator module with a cladded piezo actuator
EP2031669B1 (en) Piezo actuator module having a piezo actuator sleeve and method for its manufacture
EP2013923B1 (en) Piezoactuator with a casing
DE102019103569B4 (en) Lead frame for an electric vehicle battery device
EP1936708A2 (en) Actuator module with a cladded piezo actuator and method for its manufacture
DE102010055004A1 (en) Piezoelectric element stack for piezoelectric injector used for injection of fuel into internal combustion engine, has insulating layer having several indentations formed in circumference and bulges formed between indentations
EP2071645B1 (en) Piezo actuator module with a multiple structure of Piezo elements
EP1768198B1 (en) Piezoelectric actuator
EP2109160A1 (en) Piezo actuator module for an assembly surrounded by a flowing medium
DE102015213003A1 (en) Piezo actuator module and piezo injector

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): BW GH GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase