EP2090771A1 - Fuel injector with a directly controlled valve needle - Google Patents
Fuel injector with a directly controlled valve needle Download PDFInfo
- Publication number
- EP2090771A1 EP2090771A1 EP09100004A EP09100004A EP2090771A1 EP 2090771 A1 EP2090771 A1 EP 2090771A1 EP 09100004 A EP09100004 A EP 09100004A EP 09100004 A EP09100004 A EP 09100004A EP 2090771 A1 EP2090771 A1 EP 2090771A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- actuator
- sleeve
- fuel injector
- elastomer
- injector according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000446 fuel Substances 0.000 title claims abstract description 37
- 229920001971 elastomer Polymers 0.000 claims abstract description 32
- 239000000806 elastomer Substances 0.000 claims abstract description 32
- 238000002347 injection Methods 0.000 claims description 5
- 239000007924 injection Substances 0.000 claims description 5
- 238000002485 combustion reaction Methods 0.000 claims description 4
- 238000007789 sealing Methods 0.000 description 20
- 238000000576 coating method Methods 0.000 description 5
- 238000001816 cooling Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 101100390736 Danio rerio fign gene Proteins 0.000 description 3
- 101100390738 Mus musculus Fign gene Proteins 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000000284 resting effect Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000010292 electrical insulation Methods 0.000 description 1
- 230000009975 flexible effect Effects 0.000 description 1
- 229920001973 fluoroelastomer Polymers 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M51/00—Fuel-injection apparatus characterised by being operated electrically
- F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
- F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
- F02M61/16—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
-
- 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
- F02M63/0057—Means for avoiding fuel contact with valve actuator, e.g. isolating actuators by using bellows or diaphragms
Definitions
- the invention is based on a fuel injector with a directly controlled valve needle according to the preamble of patent claim 1.
- Such a fuel injector is for example by the DE 10 2005 004 738 A1 known.
- a hydraulic coupler is provided between the piezo actuator and the nozzle needle, and the needle movement follows directly the actuator movement.
- the piezo actuator is arranged in an actuator receiving space, which is connected to a high-pressure accumulator of the fuel.
- DE 10 2005 004 738 A1 Nothing is said about the sealing of the piezo actuator with respect to the fuel.
- the object of the invention is to protect the piezo actuators, which are located in the injector, from moisture (diesel, H 2 O, RME, other electrically conductive substances), particles and suspended solids and the high pressures, pressure and temperature fluctuations.
- the compensating element which may be designed as a sleeve, annular piston or piston, is pushed axially in the direction of the actuator head until the elastomer has reached its maximum volume expansion.
- the elastomer contracts and thereby reduces its volume, and the compensation element is now pushed back over the applied high pressure of the fuel and tracked the elastomer.
- the compensation element thus ensures the necessary lifting and temperature compensation on the actuator module (-40 to +160 ° C).
- the permeation of moisture (diesel, H 2 O, RME, other electrically conductive substances) via suitable high-pressure sealing elements, coatings or coating geometries must be reduced to a minimum.
- the design with a separation of temperature compensation and functional movement allows a considerable gain in space and thus allows a more robust structural design.
- the components can, for example, increase the radial forces with additional geometric adjustments and thus achieve a support of the sealing force.
- the in Fig. 1 shown fuel injector 1 has an injector 2 with a nozzle body 3 , which projects with its lower end into a combustion chamber of an internal combustion engine. Between injector housing 2 and nozzle body 3, an intermediate plate 4 is arranged with a guide bore 5 , in which a valve or nozzle needle 6 is guided axially displaceable. Between the tip of the nozzle needle 6 and the nozzle body 3, a sealing seat 7 is formed, which are arranged downstream of the injection nozzle 8 formed in the nozzle body 3 and projecting into the combustion chamber. In the nozzle body 3, the sealing seat 7 is preceded by a high-pressure chamber 9 is formed.
- the injector housing 2 has an actuator receiving space 10 in an upper area, to which a fuel inlet 11 is connected.
- the fuel inlet 11 is connected to a high pressure system, for example to a common rail system a diesel injector, connected.
- a connecting bore 12 leads through the intermediate plate 4 , so that the fuel introduced via the fuel feed 11 into the actuator receiving space 10 is conducted at high pressure into the high-pressure space 9 assigned to the nozzle needle 6.
- a piezoelectric actuator 13 is arranged, which comprises a fixedly connected to the injector 2 actuator base 14, an actuator head 15 and between the actual piezoelectric element (piezo stack) 16 , wherein the actuator head 15 and the piezo stack 16 relative to the actuator 14 in the Diameter are reduced.
- the actuator head 15 is also guided in the guide bore 5 and defined therein together with the nozzle needle 6 a coupler space 17, whereby the nozzle needle 6 is hydraulically coupled with the piezoelectric actuator 13. Furthermore, engages the nozzle needle 6 a supported on the intermediate plate 4 closing spring 18 , which presses the nozzle needle 6 in the closing direction.
- the sealing seat 7 is closed by the nozzle needle 6.
- the fuel pressure reached via the fuel inlet 11 into the actuator accommodating space 10 is in the high-pressure chamber 9 and in the coupler chamber 17 equally.
- acting in the coupler chamber 17 on the nozzle needle 6 hydraulic closing force is equal to acting in the high pressure chamber 9 on the nozzle needle 6 hydraulic opening force, so that the nozzle needle 6 is pressed by the closing spring 18 in its closed position. If the voltage at the piezoelectric actuator 13 is reduced or the piezoactuator 13 is de-energized, the length of the piezoelectric actuator 13 is reduced in the vertical direction and the actuator head 15 moves upwards.
- the volume increases in the coupler space 17, whereby there takes place a pressure reduction and acting on the nozzle needle 6 closing force of the closing spring 18 is overcome.
- the nozzle needle 6 lifts off from the sealing seat 7 and releases the injection openings 8 for fuel injection.
- an extension of the piezoelectric actuator 13 is again introduced, which generates a pressure increase in the coupler chamber 17, which leads to the closing of the nozzle needle 6.
- the closing spring 18 acting on the nozzle needle 6 then holds the nozzle needle 6 on the sealing seat 7, ie in the closed state.
- the piezo stack 16 is surrounded by a sleeve 20 made of metal floating on the piezoelectric actuator 13, ie axially displaceable, is stored and the piezo stack 16 seals against the Aktorfactraum 10 and thus protects against fuel and water ingress.
- a bottom seal (sliding seal) 21 is integrated, on which the sleeve 20 is mounted axially displaceable.
- a ring 22 is welded on the inside high pressure tight, in which a head gasket (sliding seal) 23 is integrated, which is mounted axially displaceably on the actuator head 15.
- the annular space between the sleeve 20 and piezoelectric actuator 13 is filled with an elastomer 24 (eg fluoroelastomers), the heat dissipation from the piezo stack 16 to the sleeve 20, for electrical insulation and as a support member relative to the sleeve 20 under the prevailing system pressures of up to 2500 bar serves.
- elastomer 24 eg fluoroelastomers
- seals 21, 23 metallic and elastomeric high-pressure sealing elements can be used.
- paired elements on the actuator base 14 and the actuator head 15 in strength and coefficient of thermal expansion should be chosen so that a close tolerance with low radial expansion is possible. In this way, a suitable high pressure seal is possible.
- the floating sleeve 20 can compensate for the volume change of the elastomer 24 abutting its one annular end surface 25a by being axially displaceable along the base gasket 21.
- the actuator head 15 can slide along the head gasket 23 and at this point converts its functional movement.
- the sleeve 20 Upon thermal expansion of the elastomer 24 supported on the actuator foot 14, the sleeve 20 is pushed axially in the direction of the actuator head 15 and slides with its sealing elements 21, 23 along the actuator foot 14 and actuator head 15 until the elastomer 24 has reached its maximum volume expansion.
- the elastomer 24 contracts and thereby reduces its volume.
- the sleeve 20 is now pushed back over the applied at its other annular end face 25b high pressure of the fuel and the elastomer 24 tracked.
- the sleeve 20 is subjected to a higher force in the head area due to the annular end face 25b in the head area than in the foot area.
- the sleeve 20 thus always ensures a pressure equalization inside and outside the sleeve 20, so that they are at high Pressing and possible suppression is not deformed.
- Due to the additional annular end face 25, the sleeve 20 thus forms a movable differential piston, the necessary lifting and temperature compensation on Piezo actuator 13 in the temperature range of -40 to +160 ° C ensures.
- the permeation of moisture (diesel, water, RME) or other electrically conductive substances via suitable coatings, coating geometries or suitable high-pressure sealing elements 21, 23 on the ring 22 and the actuator base 14 to a minimum.
- the material pairings of sleeve 20, actuator base 14, actuator head 15 and ring 22 must be selected in terms of strength and thermal expansion coefficient so that the sealing elements 21, 23 can be designed as small as possible and no geometric overdetermination between the movable sealing points takes place.
- the ring 22 and the actuator base 14 can be adapted and designed in their geometry and shape according to the selected type of seal.
- an additional radial contact pressure of the foot and head gaskets 21, 23 can be achieved.
- the sleeve 20 can apply an additional radial force by appropriate geometric design and thus achieve a support of the sealing force.
- the undercut of the sleeve 20 allows an additional radial force on the head gasket 23. In this way, wear and temperature differences can be compensated.
- the radial contact pressure can still be increased by springs 27 , which radially spread apart the legs 28 of the H-shaped cross section.
- the ring 22 may have a U-shaped cross-section only on its end face facing the actuator receiving space 10.
- an additional radial contact pressure can be achieved by reducing the wall of the sleeve 20.
- the sleeve 20 is welded at one end to the actuator base 14 in a high pressure-tight manner and closed at the other end by an annular piston 40 , which is mounted so as to be axially displaceable by sliding seals 41, 42 in the sleeve 20 and on the actuator head 15.
- the coupler space 17 is formed within a coupler sleeve 43 , in which the actuator head 15 and optionally also the nozzle needle 6 are guided displaceably.
- the two sliding seals 41, 42 are on Ring piston 40 is provided and allow the sliding and high pressure-tight sealing of the annular piston 40 relative to the sleeve 20 (temperature compensation) and relative to the actuator head 15 (Brushubterrorism).
- the material pairings of actuator head 15, sleeve 20 and annular piston 40 should be chosen in terms of strength and thermal expansion coefficient so that the sliding seals 41, 42 can be designed as small as possible.
- seals 41, 42 metallic and elastomeric high-pressure sealing elements can be used.
- the annular piston 40 can be designed in length and shape according to the selected type of seal.
- the annular piston 40 can compensate for the change in volume of the elastomer 24 resting against its one annular end surface 44a by axially displacing itself with its outer sliding seal 41 within the sleeve 20.
- the actuator head 15 can slide along the inner sliding seal 42 and at this point reverses its functional movement.
- the annular piston 40 In a thermal expansion of the supported on the actuator base 14 elastomer 24, the annular piston 40 is pushed to increase the volume axially in the direction of the free actuator head end and slides with its sliding seals 41, 42 high pressure within the sleeve 20 and the actuator head 15 along until the elastomer 24 its maximum Volume expansion has reached. Upon cooling, the elastomer 24 contracts and thereby reduces its volume. The annular piston 40 is now pushed back over the applied at its other annular end face 44b high pressure of the fuel and the elastomer 24 tracked. The annular piston 40 thus always ensures a pressure equalization with respect to the sleeve 20, so that it is not deformed at high pressure. To assist the ring piston 40 may be biased with a supported on the coupler sleeve 43 spring 45 in contact with the elastomer 24.
- Fig. 5a can be achieved by two annular grooves 46, so an H-shaped cross-section of the annular piston 40, an additional radial contact force of the sliding seal 41, 42.
- the radial contact force can still by analog springs as in Fig. 3a increase.
- a bellows 47 can be formed or embossed on the sleeve 20, which - in particular in the case of a geometric overdetermination in the tolerance chain (actuator foot 14, sleeve 20, annular piston 40, actuator head 15) - a radial tolerance compensation on the piezoelectric actuator 13th allows.
- the bellows 46 can reduce jamming or increased wear on the annular piston 40, the sleeve 20 and the actuator head 15 due to its radially and axially flexible properties. In addition to a classic Blagpatented other compensation stampings on the sleeve 20 are possible.
- the sleeve 20 is welded to the actuator base 14 and the actuator head 15 in a high-pressure-tight manner and is formed as a bellows 47 therebetween.
- a piston 60 is guided in a guide bore 61 of the actuator head 15 by means of a sliding seal or coating 62 axially displaceable and high pressure- tight and limited in the guide bore 61 has two piston chambers 63a, 63b .
- Upper piston chamber 63a is connected via elastomer inlet bores 64 with the annulus filled by the elastomer 24 and the lower piston chamber 63b via high-pressure inlet bores 65 with the Aktorfactraum 10.
- springs 66 can be used to compensate for any existing differences in power between elastomer 24 and fuel and friction forces.
- the guide bore 61 is formed in the actuator head 15 blind bore, which is closed with a closure element 67 .
- the sleeve 20 takes on their bellows structure or other Wegausreterete geometry, the lifting movement of the actuator function in the axial direction.
- the piston 60 compensates only for the thermal expansion of the elastomer 24 and the other components and thus prevents radial expansion or possible overuse of the sleeve 20.
- pressure fluctuations in the Aktorfactraum 10 are compensated by the piston 60 so that the sleeve 20 is pressure balanced at all times and not deformed unduly.
- the piston 60 Upon thermal expansion of the elastomer 24 supported on the actuator root 14, the piston 60 is pushed so far in the direction of the free actuator head end by the elastomer 24 resting on its one piston surface 68a until the elastomer 24 has reached its maximum volume expansion.
- the elastomer 24 is ideally connected without stiffness, pressure and flow losses to the piston 60, with the appropriate vote on the number, bore diameter and shape of the inlet holes 64 takes place.
- the elastomer 24 contracts and thereby reduces its volume.
- the piston 60 is now pushed back over the prevailing in the lower piston chamber 63b and acting on its other piston surface 68b high pressure of the fuel and the elastomer 24th tracked.
- the piston 60 thus always ensures a pressure equalization inside and outside the sleeve 20, so that it is not deformed at high pressures and possible suppression.
- the material pairings of sleeve 20, piston 60, actuator base 14 and actuator head 15 should be chosen in terms of strength and thermal expansion coefficient so that the sliding seal 62 on the piston 60 can be designed as small as possible.
- metallic and elastomeric high-pressure sealing elements can be used.
- the piston 60 can be adapted and designed in its geometry and shape according to the selected type of seal.
- an additional radial contact pressure of the sliding seal 62 can be achieved in each case by two annular grooves 69, that is, by a double-H-shaped cross-section of the piston 60.
- an additional radial contact pressure of the sliding seal 62 can also be achieved in each case by an annular groove 69, that is, by an H-shaped cross section of the piston 60.
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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
Description
Die Erfindung geht aus von einem Kraftstoffinjektor mit einer direkt gesteuerten Ventilnadel nach der Gattung des Patentanspruchs 1.The invention is based on a fuel injector with a directly controlled valve needle according to the preamble of patent claim 1.
Ein derartiger Kraftstoffinjektor ist beispielsweise durch die
Aufgabe der Erfindung ist es, die Piezo-Aktoren, welche sich im Injektorgehäuse befinden, vor Feuchtigkeit (Diesel, H2O, RME, sonstigen elektrisch leitenden Substanzen), Partikeln und Schwebstoffen sowie den hohen Drücken, Druck- und Temperaturschwankungen zu schützen.The object of the invention is to protect the piezo actuators, which are located in the injector, from moisture (diesel, H 2 O, RME, other electrically conductive substances), particles and suspended solids and the high pressures, pressure and temperature fluctuations.
Bei einer Wärmeausdehnung des Elastomers wird das Ausgleichselement das als Hülse, Ringkolben oder Kolben ausgeführt sein kann, axial in Richtung Aktorkopf geschoben, bis das Elastomer seine maximale Volumenausdehnung erreicht hat. Bei Abkühlung zieht sich das Elastomer zusammen und verringert dabei sein Volumen, und das Ausgleichselement wird nun über den anliegenden Hochdruck des Kraftstoffs zurückgeschoben und dem Elastomer nachgeführt. Das Ausgleichelement stellt so den nötigen Hub- und Temperaturausgleich am Aktormodul (-40 bis +160 °C) sicher. Dabei ist die Permeation von Feuchtigkeit (Diesel, H2O, RME, sonstigen elektrisch leitenden Substanzen) über geeignete Hochdruckdichtelemente, Beschichtungen oder Beschichtungsgeometrien auf ein Minimum zu reduzieren. Die Auslegung mit einer Trennung von Temperaturausgleich und Funktionsbewegung ermöglicht einen erheblichen Gewinn an Bauraum und ermöglicht so eine robustere konstruktive Auslegung. Die Bauteile können mit zusätzlichen geometrischen Anpassungen z.B. die Radialkräfte erhöhen und so eine Unterstützung der Dichtkraft erreichen.Upon thermal expansion of the elastomer, the compensating element, which may be designed as a sleeve, annular piston or piston, is pushed axially in the direction of the actuator head until the elastomer has reached its maximum volume expansion. Upon cooling, the elastomer contracts and thereby reduces its volume, and the compensation element is now pushed back over the applied high pressure of the fuel and tracked the elastomer. The compensation element thus ensures the necessary lifting and temperature compensation on the actuator module (-40 to +160 ° C). The permeation of moisture (diesel, H 2 O, RME, other electrically conductive substances) via suitable high-pressure sealing elements, coatings or coating geometries must be reduced to a minimum. The design with a separation of temperature compensation and functional movement allows a considerable gain in space and thus allows a more robust structural design. The components can, for example, increase the radial forces with additional geometric adjustments and thus achieve a support of the sealing force.
Weitere Vorteile und vorteilhafte Ausgestaltungen des Gegenstands der Erfindung sind der Beschreibung, der Zeichnung und den Ansprüchen entnehmbar.Further advantages and advantageous embodiments of the subject invention are the description, the drawings and claims removed.
Ausführungsbeispiele des erfindungsgemäßen Kraftstoffinjektors sind in der Zeichnung dargestellt und in der nachfolgenden Beschreibung näher erläutert. Die in den Figuren gezeigten Merkmale sind rein schematisch und nicht maßstäblich zu verstehen. Es zeigt:
- Fig. 1
- eine erste Ausführungsform des erfindungsgemäßen Kraftstoffinjektors in einem Längsschnitt;
- Fig. 2
- eine vergrößerte Ansicht eines in
Fig. 1 gezeigten, nach außen abgedichteten Aktormoduls mit einem Differentialkolben; - Fign. 3a und 3b
- zwei Abdichtungsmodifikationen des in
Fig. 2 gezeigten Aktormoduls; - Fig. 4
- eine zweite Ausführungsform des erfindungsgemäßen Kraftstoffinjektors mit einem nach außen abgedichteten Aktormodul und mit einem Ringkolben in einer Darstellung analog zu
Fig. 2 ; - Fign. 5a und 5b
- zwei Abdichtungsmodifikationen des in
Fig. 4 gezeigten Aktormoduls; - Fig. 6
- eine dritte Ausführungsform des erfindungsgemäßen Kraftstoffinjektors mit einem nach außen abgedichteten Aktormodul und mit einem integrierten Ausgleichkolben in einer Darstellung analog zu
Fig. 2 ; und - Fign. 7a und 7b
- zwei Abdichtungsmodifikationen des in
Fig. 6 gezeigten Aktormoduls.
- Fig. 1
- a first embodiment of the fuel injector according to the invention in a longitudinal section;
- Fig. 2
- an enlarged view of an in
Fig. 1 shown, sealed to the outside actuator module with a differential piston; - FIGS. 3a and 3b
- two sealing modifications of the in
Fig. 2 shown actuator module; - Fig. 4
- a second embodiment of the fuel injector according to the invention with an outwardly sealed actuator module and with an annular piston in a representation analogous to
Fig. 2 ; - FIGS. 5a and 5b
- two sealing modifications of the in
Fig. 4 shown actuator module; - Fig. 6
- a third embodiment of the fuel injector according to the invention with an outwardly sealed actuator module and with an integrated balancing piston in a representation analogous to
Fig. 2 ; and - FIGS. 7a and 7b
- two sealing modifications of the in
Fig. 6 shown actuator module.
Der in
Im Aktoraufnahmeraum 10 ist ein Piezo-Aktor 13 angeordnet, der einen mit dem Injektorgehäuse 2 fest verbundenen Aktorfuß 14, einen Aktorkopf 15 und dazwischen das eigentliche piezoelektrische Element (Piezostapel) 16 umfasst, wobei der Aktorkopf 15 und der Piezostapel 16 gegenüber dem Aktorfuß 14 im Durchmesser reduziert sind. Der Aktorkopf 15 ist ebenfalls in der Führungsbohrung 5 geführt und definiert darin zusammen mit der Düsennadel 6 einen Kopplerraum 17, wodurch die Düsennadel 6 mit dem Piezo-Aktor 13 hydraulisch bewegungsgekoppelt ist. Weiterhin greift an der Düsennadel 6 eine an der Zwischenplatte 4 abgestützte Schließfeder 18 an, die die Düsenadel 6 in Schließrichtung drückt.The in
In
Im gezeigten geschlossenen Zustand der Einspritzöffnungen 8 ist der Dichtsitz 7 durch die Düsennadel 6 geschlossen. Der über den Kraftstoffzulauf 11 in den Aktoraufnahmeraum 10 gelangte Kraftstoffdruck liegt im Hochdruckraum 9 und im Kopplerraum 17 gleichermaßen an. In diesem Zustand ist die im Kopplerraum 17 auf die Düsennadel 6 wirkende hydraulische Schließkraft gleich der im Hochdruckraum 9 auf die Düsennadel 6 wirkende hydraulische Öffnungskraft, so dass die Düsennadel 6 durch die Schließfeder 18 in ihre geschlossene Lage gedrückt ist. Wird die Spannung am Piezo-Aktor 13 reduziert bzw. der Piezo-Aktor 13 stromlos geschaltet, wird die Länge des Piezo-Aktors 13 in vertikaler Richtung reduziert und der Aktorkopf 15 bewegt sich nach oben. Dadurch vergrößert sich das Volumen im Kopplerraum 17, wodurch dort eine Druckreduzierung stattfindet und die auf die Düsennadel 6 wirkende Schließkraft der Schließfeder 18 überwunden wird. Die Düsennadel 6 hebt vom Dichtsitz 7 ab und gibt die Einspritzöffnungen 8 für eine Kraftstoffeinspritzung frei. Durch Bestromen des Piezo-Aktors 13 wird wieder eine Verlängerung des Piezo-Aktors 13 eingeleitet, die im Kopplerraum 17 einen Druckanstieg erzeugt, der zum Schließen der Düsennadel 6 führt. Die auf die Düsennadel 6 wirkende Schließfeder 18 hält die Düsennadel 6 dann am Dichtsitz 7, also im geschlossenen Zustand.In the illustrated closed state of the injection openings 8, the sealing seat 7 is closed by the
Wie in
Die schwimmende Hülse 20 kann die Volumenänderung des an ihrer einen Ringstirnfläche 25a anliegenden Elastomers 24 ausgleichen, indem sie sich entlang der Fußdichtung 21 axial verschieben lässt. Der Aktorkopf 15 kann entlang der Kopfdichtung 23 gleiten und setzt an dieser Stelle seine Funktionsbewegung um. Bei einer Wärmeausdehnung des am Aktorfuß 14 abgestützten Elastomers 24 wird die Hülse 20 axial in Richtung Aktorkopf 15 geschoben und gleitet dabei mit ihren Dichtelementen 21, 23 hochdruckdicht am Aktorfuß 14 und Aktorkopf 15 entlang, bis das Elastomer 24 seine maximale Volumenausdehnung erreicht hat. Bei Abkühlung zieht sich das Elastomer 24 zusammen und verringert dabei sein Volumen. Die Hülse 20 wird nun über den an ihrer anderen Ringstirnfläche 25b anliegenden Hochdruck des Kraftstoffs zurückgeschoben und dem Elastomer 24 nachgeführt. Unterstützend wirkt dabei, dass unter den isostatischen Druckverhältnissen im Aktoraufnahmeraum 10 die Hülse 20 aufgrund der Ringstirnfläche 25b im Kopfbereich mit einer höheren Kraft beaufschlagt ist als im Fußbereich Die Hülse 20 sorgt so immer für einen Druckausgleich innerhalb und außerhalb der Hülse 20, sodass diese bei hohen Drücken und möglichen Unterdrücken nicht verformt wird. Aufgrund der zusätzlichen Ringstirnfläche 25 bildet die Hülse 20 somit einen beweglichen Differentialkolben, der den nötigen Hub- und Temperaturausgleich am Piezo-Aktor 13 im Temperaturbereich von -40 bis +160 °C sicherstellt. Dabei ist die Permeation von Feuchtigkeit (Diesel, Wasser, RME) oder von sonstigen elektrisch leitenden Substanzen über geeignete Beschichtungen, Beschichtungsgeometrien bzw. geeigneten Hochdruckdichtelemente 21, 23 am Ring 22 und am Aktorfuß 14 auf ein Minimum zu reduzieren. Die Werkstoffpaarungen von Hülse 20, Aktorfuß 14, Aktorkopf 15 und Ring 22 müssen in Festigkeit und Wärmeausdehungskoeffizienten so gewählt werden, dass die Dichtelemente 21, 23 so klein wie möglich ausgelegt werden können und keine geometrische Überbestimmung zwischen den beweglichen Dichtstellen stattfindet. Der Ring 22 und der Aktorfuß 14 können in ihrer Geometrie und Form entsprechend der gewählten Dichtungsart angepasst und gestaltet werden. Durch das Anformen einer Ausgleichsgeometrie, z.B. Balgstrukturen, an der Hülse 20 können radiale Toleranz-, Verschleiß-, Hub-, und Temperaturausgleiche unterstützt werden.The floating
Wie in
Bei der in
Wie in
Bei der in
Wie in
Claims (9)
dadurch gekennzeichnet,
dass das piezoelektrische Element (16) von einer Hülse (20) umgeben ist, die hochdruckdicht mit dem Aktorfuß (14) und dem Aktorkopf (15) verbunden ist, dass der zwischen der Hülse (20) und dem piezoelektrischen Element (16) vorhandene Ringraum mit einem Elastomer (24) ausgefüllt ist und dass der Aktorkopf (15) ein axial verschiebbar geführtes Ausgleichselement (22; 40; 60) aufweist, auf dessen eine Stirnseite (25a; 44a; 68a) das Elastomer (24) und auf dessen andere Stirnseite (25b; 44b; 68b) der Hochdruck des Kraftstoffs drückt.Fuel injector (1) with a directly controlled valve needle (6) which opens or closes depending on their position at least one injection port (8) for injecting fuel into a combustion chamber, and with a piezo actuator (13) having a housing fixed Actuator foot (14), one with the valve needle (6) motion-coupled actuator head (15) and between at least one piezoelectric element (16),
characterized,
in that the piezoelectric element (16) is surrounded by a sleeve (20), which is connected in a high-pressure-tight manner to the actuator foot (14) and the actuator head (15), that the annular space present between the sleeve (20) and the piezoelectric element (16) filled with an elastomer (24) and that the actuator head (15) has an axially displaceably guided compensation element (22; 40; 60), on whose one end face (25a; 44a; 68a) the elastomer (24) and on the other end face (25b; 44b; 68b) presses the high pressure of the fuel.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE200810008847 DE102008008847A1 (en) | 2008-02-13 | 2008-02-13 | Fuel injector with a directly controlled valve needle |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2090771A1 true EP2090771A1 (en) | 2009-08-19 |
EP2090771B1 EP2090771B1 (en) | 2011-08-17 |
Family
ID=40673675
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20090100004 Expired - Fee Related EP2090771B1 (en) | 2008-02-13 | 2009-01-05 | Fuel injector with a directly controlled valve needle |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP2090771B1 (en) |
DE (1) | DE102008008847A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3112661A1 (en) * | 2015-06-29 | 2017-01-04 | Delphi International Operations Luxembourg S.à r.l. | Sealing arrangement |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1424492A2 (en) * | 2002-11-26 | 2004-06-02 | Robert Bosch Gmbh | Valve for control of fluids with a nozzle and a control valve |
EP1452729A1 (en) * | 2003-02-28 | 2004-09-01 | Robert Bosch Gmbh | Fuel injector |
DE10310789A1 (en) * | 2003-03-12 | 2004-09-23 | Robert Bosch Gmbh | Fuel injection valve for IC engine fuel injection system has fuel feed with connection point and pipe extending to foot of actuator for movement of valve closure relative to valve seat surface |
EP1561942A1 (en) * | 2004-01-29 | 2005-08-10 | Siemens VDO Automotive S.p.A. | Fluid injector and its method of manufacture |
DE102005004738A1 (en) | 2005-02-02 | 2006-08-10 | Robert Bosch Gmbh | Fuel injector with direct needle control for an internal combustion engine |
EP1741922A1 (en) * | 2005-06-28 | 2007-01-10 | Robert Bosch Gmbh | Fuel injector |
WO2009059862A1 (en) * | 2007-11-09 | 2009-05-14 | Robert Bosch Gmbh | Piezoelectric actuator module |
-
2008
- 2008-02-13 DE DE200810008847 patent/DE102008008847A1/en not_active Withdrawn
-
2009
- 2009-01-05 EP EP20090100004 patent/EP2090771B1/en not_active Expired - Fee Related
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1424492A2 (en) * | 2002-11-26 | 2004-06-02 | Robert Bosch Gmbh | Valve for control of fluids with a nozzle and a control valve |
EP1452729A1 (en) * | 2003-02-28 | 2004-09-01 | Robert Bosch Gmbh | Fuel injector |
DE10310789A1 (en) * | 2003-03-12 | 2004-09-23 | Robert Bosch Gmbh | Fuel injection valve for IC engine fuel injection system has fuel feed with connection point and pipe extending to foot of actuator for movement of valve closure relative to valve seat surface |
EP1561942A1 (en) * | 2004-01-29 | 2005-08-10 | Siemens VDO Automotive S.p.A. | Fluid injector and its method of manufacture |
DE102005004738A1 (en) | 2005-02-02 | 2006-08-10 | Robert Bosch Gmbh | Fuel injector with direct needle control for an internal combustion engine |
EP1741922A1 (en) * | 2005-06-28 | 2007-01-10 | Robert Bosch Gmbh | Fuel injector |
WO2009059862A1 (en) * | 2007-11-09 | 2009-05-14 | Robert Bosch Gmbh | Piezoelectric actuator module |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3112661A1 (en) * | 2015-06-29 | 2017-01-04 | Delphi International Operations Luxembourg S.à r.l. | Sealing arrangement |
Also Published As
Publication number | Publication date |
---|---|
DE102008008847A1 (en) | 2009-08-27 |
EP2090771B1 (en) | 2011-08-17 |
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