EP3184803B1 - Fuel injector - Google Patents

Fuel injector Download PDF

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Publication number
EP3184803B1
EP3184803B1 EP16197784.8A EP16197784A EP3184803B1 EP 3184803 B1 EP3184803 B1 EP 3184803B1 EP 16197784 A EP16197784 A EP 16197784A EP 3184803 B1 EP3184803 B1 EP 3184803B1
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EP
European Patent Office
Prior art keywords
coupler
fuel injector
piston
leaf spring
valve
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EP16197784.8A
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German (de)
French (fr)
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EP3184803A1 (en
Inventor
Andreas Rau
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of EP3184803A1 publication Critical patent/EP3184803A1/en
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    • 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
    • F02M47/00—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
    • F02M47/02—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
    • F02M47/027—Electrically actuated valves draining the chamber to release the closing pressure
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/70—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger
    • F02M2200/703—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic
    • F02M2200/705—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic with means for filling or emptying hydraulic chamber, e.g. for compensating clearance or thermal expansion

Definitions

  • the invention relates to a fuel injector of a fuel injection system of an internal combustion engine, wherein the fuel injector comprises a hydraulic coupler having a movable in a coupler body coupler piston and a coupled thereto via a coupler gap also movable in the coupler body working piston, and wherein the coupler gap via at least one filling channel with a is connected outside the coupler body arranged low pressure space.
  • Such a fuel injector is from the DE 10 2009 001 266 A1 known.
  • This fuel injector of a common rail fuel injection system has a hydraulic coupler which has a coupler piston movable in a coupler body and a piston which is also coupled to it in the coupler body via a coupler gap.
  • the coupler gap is connected via a filling channel with a arranged outside the coupler body low pressure space.
  • This filling channel is arranged in the coupler body, that the filling channel is closed during a downward movement of the coupler piston, while the filling channel is opened during an upward movement of the coupler piston.
  • a fuel injection device with a hydraulic coupler in which two coaxially arranged coupling pistons limit a fillable via a connecting line filling space.
  • the invention has for its object to provide a fuel injector with a coupler, wherein the filling of the coupler gap space is improved with hydraulic fluid.
  • This object is achieved in that in the region of a connection of the filling channel with the Kopplerspaltraum an opening in the direction of the coupler gap, one-piece and elastically formed valve is arranged.
  • This embodiment is based on the finding that with each switching operation in the coupler, a significantly higher pressure than in the surrounding low-pressure space arises. This results in the games on the piston guides of the coupler piston and the working piston in the coupler body to a leakage from the coupler, more precisely from the Kopplerspaltraum out.
  • a hydraulic coupler has a speed limit, with which it can be operated at a required number of injections in dependence on the pressure of the fuel.
  • the inventive design of the coupler a significantly improved refilling is achieved, which significantly improves the speed resistance of the coupler.
  • the valve is designed as an axially slotted sleeve.
  • Such axially slotted sleeve is easy to manufacture and also has a high closing accuracy of the filling channel.
  • the valve or the slotted sleeve is a leaf spring valve.
  • This leaf spring valve is very first simply constructed and also extremely durable by a very small adjustment. Furthermore, only a very small dead volume is shown by the design of the valve as a leaf spring valve and the arrangement of the leaf spring valve within the coupler body. Furthermore, by a good fit of the leaf spring valve in the coupler body to close the filling channel of the coupler gap space, if any, increased only very slightly, which is why the coupler function over other known solutions is improved.
  • the diameter of the leaf spring valve is greater than the inner diameter of the coupler body in the region of the mouth of the filling channel in the coupler gap. Because of this slightly larger outer diameter of the leaf spring valve than the inner diameter of the coupler body and the radially resilient properties, the leaf spring valve is against the inner wall of the coupler body at a higher pressure in the coupler gap than in the low pressure chamber and thus reliably seals the filling channel.
  • an actuator of the fuel injector is actuated, a movement of the coupler piston into the coupler gap space results in an immediate buildup of pressure in the coupler, which, as described above, improves the function of the coupler.
  • a securing device for fixing the leaf spring valve is provided.
  • This safety device is generally designed so that the leaf spring valve is neither radially nor axially in relation to the mouth of the filling channel in particular during operation of the fuel injector can move. This ensures that a possible failure of the coupler is excluded by a no longer be shut off by the leaf spring valve filling channel.
  • the securing device is an anti-rotation device.
  • Such anti-rotation device is usually sufficient for trouble-free operation of the coupler.
  • the anti-rotation device is in a retaining groove of the coupler piston (or the coupler body) engaging the fold of the leaf spring valve.
  • the rotation can also be formed by a separate component in the form of, for example, a metal sheet, which cooperates with the coupler piston (or the coupler body), so that the leaf spring valve can not rotate.
  • the anti-rotation device is a nose which cooperates with a recess either in the coupler body or else with a corresponding design of the recess in the coupler piston.
  • the material of the leaf spring valve spring steel This is the most suitable material for producing the leaf spring valve.
  • FIG. 1 shows a fuel injector 1 of a common rail injection system for injecting fuel into a combustion chamber, not shown, of an internal combustion engine.
  • a high-pressure pump 2 conveys fuel from a tank 3 into a high-pressure accumulator 4.
  • fuel in particular diesel fuel
  • the high-pressure accumulator 4 of the fuel injector 1 is connected in addition to other, not shown fuel injectors via a high pressure line 5.
  • the high-pressure line 5 opens into an axial supply channel 6 belonging to a high-pressure region of the fuel injector 1, through which fuel flows into a pressure chamber 7.
  • the fuel flows from the pressure chamber 7 in the axial direction past an injector needle 8 through injection bores 16 into the combustion chamber of the internal combustion engine.
  • the fuel injector 1 is connected via an injector return port 9 to a return line 10.
  • a control quantity of fuel Via the return line 10, a control quantity of fuel, which will be explained below, can flow away from the fuel injector 1 to the tank 3 and from there can again be supplied to the high-pressure circuit.
  • the injector needle 8 is guided axially adjustable within a stepped bore 11 of an injector needle body 12.
  • the injector needle body 12 is clamped in conjunction with a throttle plate and a valve body against a holding body 13 by means of a clamping nut.
  • the Injektornadel 8 has at its needle tip 15 designed as a sealing surface closing surface with which the Injektornadel 8 is mounted in a tight contact with a trained within the Injektornadel stressess 12 Injektornadelianusitz. If the Injektornadel 8 rests against the Injektornadelianusitz, so is in the closed position, the fuel outlet from the at least one injection hole 16 is locked. By contrast, if the injector needle 8 is lifted off the injector needle body seat, fuel can flow from the pressure chamber 7, which is at least approximately under the pressure of the fuel in the high-pressure accumulator 4, into the combustion chamber.
  • a control chamber 17 is limited, which is supplied via an inlet throttle 18 with fuel under high pressure from the supply channel 6.
  • the pressure chamber 14 encloses a control chamber 17 limiting, spring-loaded sleeve body 32 radially outward.
  • the formed in the sleeve body 32 control chamber 17 is connected via an outlet throttle 19 with a control valve chamber 20 which is connected by means of an axially adjustable control valve element 21 with a low-pressure chamber 22 and thus with the injector return port 9.
  • the control valve element 21 is part of a normally designed as a 3/2-way valve control valve 23.
  • a first (lower) switching position befindettess control valve element 21, fuel from the control chamber 17 via the outlet throttle 19 and the control valve chamber 20 in the low pressure chamber 22 to the injector return port stream.
  • a bypass 35 opening out of the pressure chamber 14 and opening into the control valve chamber 20 is blocked by the control valve element 21.
  • befindliches control valve element 21 When in a second (upper) switching position befindliches control valve element 21, the connection between the control valve chamber 20 and the low-pressure chamber 22 is locked and the bypass 35 is released, so that the control chamber 17 via the bypass 35, the control valve chamber 20, the outlet throttle 19 and the inlet throttle 18 is brought quickly to high pressure.
  • a piezoelectric actuator 24 is provided, which is coupled via a hydraulic coupler 25 with the control valve element 21.
  • the control valve 23 can be actuated directly by the hydraulic coupler 25, more precisely by a working piston 28 of the hydraulic coupler 25 which will be explained below.
  • the piezoelectric actuator 24 is energized and expands.
  • the working piston 28 presses on the control valve element 21, which is moved away in the sequence counter to the force of a control closing spring 30 from its upper control valve seat 26 and thus releases the flow of fuel from the control chamber 17 to the injector return port while blocking the bypass 35.
  • a control closing spring 30 By adjusting the flow cross-sections of the pressure in the control chamber 17 decreases rapidly, whereby the injector needle 8 lifts from her Injektornadel stresses so that fuel can flow out of the pressure chamber 7 through the injection hole 16.
  • the energization of the piezoelectric actuator 24 is terminated, whereby the piezocrystal stack of the actuator 24 contracts and the coupler piston 27 is supported by the spring force of a Bourdon tube 38 in the drawing plane moves upward.
  • the working piston 28 presses supported by the control closing spring 30 in the plane of the drawing down against the control valve element 21. Between the working piston 28 and the control valve element 21 thus a permanent contact is ensured.
  • the working piston 28 and the control valve element 21 are moved at not energized actuator 24 upwards into the upper switching position in which the control valve element 21 rests against its upper control valve seat 26 and the hydraulic connection from the control chamber 17 to Injector return port 9 locks.
  • the fuel flowing in through the inlet throttle 18 and via the bypass 35 into the control chamber 17 ensures a rapid pressure increase in the control chamber 17 and a hydraulic closing force acting on the injector needle 8.
  • the resulting closing movement of the Injektornadel 8 is supported by a closing spring 31 which is supported at one end to the Injektornadel 8 and the second end to a control chamber 17 limiting sleeve body 32.
  • FIGS. 2 to 4 show the detailed configuration of the coupler 25 with the arranged in a stepped recess 34 in a coupler body 33 coupler piston 27 and working piston 28 in different switching positions.
  • the coupler piston 27 has a larger outer diameter than the working piston 28 and is thus arranged in the stepped recess 34 with the larger inner diameter.
  • the coupler piston 27 may also have a same or smaller diameter than the working piston 28.
  • the coupler piston 27 protrudes with an actuation-side end, on which an actuation plate 36 is arranged, out of the coupler body 33 and cooperates with the actuator 24 by means of the actuation plate 36.
  • the working piston 33 has an actuating nose 37, which - as described above - the control valve element 21 from the control valve seat 26 down ( FIG. 1 ) can press.
  • the coupler 25 has a Bourdon tube 38 which is supported on a lower annular shoulder 39 of the coupler body 33 and the actuator plate 36 and presses apart the two components.
  • a retaining ring for a working piston spring 40 is arranged on the working piston 28, which presses the working piston 28 down from the coupler body 33 to the abutment of the actuating lug 37 on the control valve element 21.
  • a filling channel 41 in the Wall of the coupler body 33 inserted is preferably a filling channel 41 in the Wall of the coupler body 33 inserted.
  • the filling channel 41 is closed in the region of an orifice in the coupler gap 29 by a one-piece and elastically deformable valve opening in the direction of the coupler gap 29 in the form of a leaf-spring valve 42 designed as a slotted sleeve.
  • the leaf spring valve 42 has a slightly larger outer diameter than the inner diameter of the coupler body 33 and the step recess 34. Due to the slightly larger outer diameter of the leaf spring valve 42 and the radially resilient properties of the leaf spring valve 42 abuts the stepped recess 34 and seals the hydraulic connection through the filling channel 41 from.
  • the valve is closed ( FIG. 2 ).
  • the leaf spring valve 42 is arranged in the region of a stepped shoulder 43 of the coupler piston 27, which saves space and has no effect on the function of the coupler 25. With regard to the arrangement of the leaf spring valve 42 but other solutions are conceivable.
  • FIG. 6 shows a basically same construction of the coupler 25 with a coupler piston 27, as has been previously described.
  • a securing device 44 is provided here, which ensures that the leaf spring valve 42 in particular does not rotate and thus reaches the region of the mouth of the filling channel 41 with a slot 45 (the slotted sleeve). In such a case, the function of the leaf spring valve 42 would not be ensured.
  • the securing device 44 is formed as an angled sheet, which is clamped to the stepped shoulder 43 of the coupler piston 27 in a suitable manner.
  • the securing device 44a may also be formed by a fold 46 of the leaf spring valve 42 at an end adjoining the slot 45.
  • the fold 46 which may also be connected to the leaf spring valve 42, for example, welded, part engages in a retaining groove 47 in the coupler piston 27 a.
  • the securing device may also be a nose, which engages in a corresponding depression in the coupler piston 27. Basically, the rotation of the leaf spring valve 42 can also take place relative to the coupler body 33.

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

Description

Die Erfindung betrifft einen Kraftstoffinjektor eines Kraftstoffeinspritzsystems einer Brennkraftmaschine, wobei der Kraftstoffinjektor einen hydraulischen Koppler aufweist, der einen in einem Kopplerkörper beweglichen Kopplerkolben und einen damit über einen Kopplerspaltraum gekoppelten ebenfalls in dem Kopplerkörper beweglichen Arbeitskolben aufweist, und wobei der Kopplerspaltraum über mindestens einen Füllkanal mit einem außerhalb des Kopplerkörpers angeordneten Niederdruckraum verbunden ist.The invention relates to a fuel injector of a fuel injection system of an internal combustion engine, wherein the fuel injector comprises a hydraulic coupler having a movable in a coupler body coupler piston and a coupled thereto via a coupler gap also movable in the coupler body working piston, and wherein the coupler gap via at least one filling channel with a is connected outside the coupler body arranged low pressure space.

Stand der TechnikState of the art

Ein derartiger Kraftstoffinjektor ist aus der DE 10 2009 001 266 A1 bekannt. Dieser Kraftstoffinjektor eines Common-Rail-Kraftstoffeinspritzsystems weist einen hydraulischen Koppler auf, der einen in einem Kopplerkörper beweglichen Kopplerkolben und einen damit über einen Kopplerspaltraum gekoppelten ebenfalls in dem Kopplerkörper beweglichen Arbeitskolben aufweist. Der Kopplerspaltraum ist über einen Füllkanal mit einem außerhalb des Kopplerkörpers angeordneten Niederdruckraum verbunden. Dieser Füllkanal ist derart in dem Kopplerkörper angeordnet, dass der Füllkanal bei einer Abwärtsbewegung des Kopplerkolbens verschlossen wird, während der Füllkanal bei einer Aufwärtsbewegung des Kopplerkolbens geöffnet wird. Durch diese Ausgestaltung soll erreicht werden, dass der Kopplerspaltraum beim Betrieb des Kraftstoffinjektors kontinuierlich mit Hydraulikfluid befüllt wird, um Leckagen entlang den Führungen des Kopplerkolbens und des Arbeitskolbens in dem Kopplerkörper auszugleichen.Such a fuel injector is from the DE 10 2009 001 266 A1 known. This fuel injector of a common rail fuel injection system has a hydraulic coupler which has a coupler piston movable in a coupler body and a piston which is also coupled to it in the coupler body via a coupler gap. The coupler gap is connected via a filling channel with a arranged outside the coupler body low pressure space. This filling channel is arranged in the coupler body, that the filling channel is closed during a downward movement of the coupler piston, while the filling channel is opened during an upward movement of the coupler piston. By means of this embodiment, it is to be achieved that the coupler gap is continuously filled with hydraulic fluid during operation of the fuel injector in order to compensate for leaks along the guides of the coupler piston and of the working piston in the coupler body.

Aus der DE 103 33 699 A1 ist weiterhin eine Kraftstoffeinspritzeinrichtung mit einem hydraulischen Koppler bekannt, bei dem zwei koaxial angeordnete Kopplerkolben einen über eine Verbindungsleitung befüllbaren Füllraum begrenzen.From the DE 103 33 699 A1 Furthermore, a fuel injection device with a hydraulic coupler is known in which two coaxially arranged coupling pistons limit a fillable via a connecting line filling space.

Der Erfindung liegt die Aufgabe zugrunde, einen Kraftstoffinjektor mit einem Koppler bereitzustellen, bei dem die Befüllung des Kopplerspaltraums mit Hydraulikfluid verbessert ist.The invention has for its object to provide a fuel injector with a coupler, wherein the filling of the coupler gap space is improved with hydraulic fluid.

Offenbarung der ErfindungDisclosure of the invention

Diese Aufgabe wird dadurch gelöst, dass im Bereich einer Verbindung des Füllkanals mit dem Kopplerspaltraum ein in Richtung des Kopplerspaltraums öffnendes, einteilig und elastisch ausgebildetes Ventil angeordnet ist. Dieser Ausgestaltung liegt die Erkenntnis zugrunde, dass bei jedem Schaltvorgang in dem Koppler ein deutlich höherer Druck als in dem umgebenden Niederdruckraum entsteht. Dies führt über die Spiele an den Kolbenführungen des Kopplerkolbens und des Arbeitskolbens in dem Kopplerkörper zu einer Leckage aus dem Koppler, genauer aus dem Kopplerspaltraum, heraus. Da die Anforderungen aktuell in die Richtung gehen, für niedrige Emissionen immer mehr Einspritzungen pro Einspritzzyklus abzusetzen, kommt es mit jeder Einspritzung zu einer Kopplerspaltraumentleerung, weshalb für die nachfolgende Einspritzung ein geringerer Ausgangsdruck im Koppler zur Verfügung steht. Dies führt zu einer Abnahme einer möglichen Einspritzmenge. In den Einspritzpausen befüllt sich der Kopplerspaltraum zwar grundsätzlich wieder, werden jedoch sehr viele Einspritzungen mit kurzen zwischenzeitlichen Abständen abgesetzt, wird der Kopplerspaltraum mehr entleert als wieder befüllt. Dies kann zum gänzlichen Ausbleiben von gewünschten Einspritzungen führen. Daher weist ein hydraulischer Koppler eine Drehzahlgrenze auf, mit der er bei einer geforderten Anzahl von Einspritzungen in Abhängigkeit vom Druck des Kraftstoffs betrieben werden kann. Durch die erfindungsgemäße Ausgestaltung des Kopplers wird eine deutlich verbesserte Wiederbefüllung erreicht, was die Drehzahlfestigkeit des Kopplers deutlich verbessert.This object is achieved in that in the region of a connection of the filling channel with the Kopplerspaltraum an opening in the direction of the coupler gap, one-piece and elastically formed valve is arranged. This embodiment is based on the finding that with each switching operation in the coupler, a significantly higher pressure than in the surrounding low-pressure space arises. This results in the games on the piston guides of the coupler piston and the working piston in the coupler body to a leakage from the coupler, more precisely from the Kopplerspaltraum out. Since the requirements currently go in the direction of deducting more and more injections per injection cycle for low emissions, there is a Koppler gap with each injection to a Kopplerspaltraeu, which is why a lower output pressure in the coupler is available for the subsequent injection. This leads to a decrease in a possible injection quantity. Although in the injection pauses the coupler gap is basically filled again, but if a large number of injections are discontinued with short intermediate intervals, the coupler gap is more emptied than refilled. This can lead to the total absence of desired injections. Therefore, a hydraulic coupler has a speed limit, with which it can be operated at a required number of injections in dependence on the pressure of the fuel. The inventive design of the coupler a significantly improved refilling is achieved, which significantly improves the speed resistance of the coupler.

Erfindungsgemäß ist das Ventil als axial geschlitzte Hülse ausgebildet. Eine solche axial geschlitzte Hülse ist einfach zu fertigen und weist zudem eine hohe Schließgenauigkeit des Füllkanals auf.
In Weiterbildung der Erfindung ist das Ventil beziehungsweise die geschlitzte Hülse ein Blattfederventil. Dieses Blattfederventil ist zunächst einmal sehr einfach aufgebaut und zudem durch eine nur sehr geringe Verstellbewegung äußerst dauerhaltbar. Weiterhin ist durch die Ausgestaltung des Ventils als Blattfederventil und die Anordnung des Blattfederventils innerhalb des Kopplerkörpers nur ein sehr geringes Totvolumen dargestellt. Weiterhin wird durch eine gute Passform des Blattfederventils in dem Kopplerkörper zum Verschluss des Füllkanals der Kopplerspaltraum, wenn überhaupt, nur sehr wenig vergrößert, weshalb die Kopplerfunktion gegenüber anderen bekannten Lösungen verbessert wird. Zudem wird dadurch die Steifigkeit des Kopplers nicht geschwächt. Daraus folgt, dass der Spannungsbedarf des Kraftstoffinjektors für eine Betätigung nicht erhöht wird, woraus letztendlich wieder eine Druckbegrenzung des Kraftstoffinjektors erhöht wird und die Drehzahlfestigkeit verbessert wird. Bei Einspritzpausen ist der Druck in dem Niederdruckraum größer als in dem Kopplerspaltraum, weswegen das Blattfederventil durch den Druck in dem Füllkanal von der Innenwand des Kopplerkörpers weggedrückt wird und somit eine hydraulische Verbindung zwischen dem Niederdruckraum und dem Kopplerspaltraum freigegeben wird. Dadurch wird im Ergebnis eine sehr schnelle Wiederbefüllung bereits zwischen Teileinspritzungen mit quasi konstanter beziehungsweise sich nicht verschlechternder Kopplerfunktion erreicht.According to the invention, the valve is designed as an axially slotted sleeve. Such axially slotted sleeve is easy to manufacture and also has a high closing accuracy of the filling channel.
In a further development of the invention, the valve or the slotted sleeve is a leaf spring valve. This leaf spring valve is very first simply constructed and also extremely durable by a very small adjustment. Furthermore, only a very small dead volume is shown by the design of the valve as a leaf spring valve and the arrangement of the leaf spring valve within the coupler body. Furthermore, by a good fit of the leaf spring valve in the coupler body to close the filling channel of the coupler gap space, if any, increased only very slightly, which is why the coupler function over other known solutions is improved. In addition, this does not weaken the stiffness of the coupler. It follows that the voltage requirement of the fuel injector for an operation is not increased, from which ultimately a pressure limit of the fuel injector is increased again and the speed stability is improved. In injection pauses, the pressure in the low pressure space is greater than in the coupler gap space, which is why the leaf spring valve is pushed away by the pressure in the filling channel of the inner wall of the coupler body and thus a hydraulic connection between the low pressure chamber and the coupler gap is released. As a result, a very fast refilling is already achieved between partial injections with a quasi-constant or non-deteriorating coupler function.

In weiterer Ausgestaltung der Erfindung ist der Durchmesser des Blattfederventils größer als der Innendurchmesser des Kopplerkörpers im Bereich der Mündung des Füllkanals in den Kopplerspaltraum. Aufgrund dieses etwas größeren Außendurchmessers des Blattfederventils als des Innendurchmessers des Kopplerkörpers sowie die radial federnden Eigenschaften liegt das Blattfederventil an der Innenwand des Kopplerkörpers bei einem höheren Druck in dem Kopplerspaltraum als in dem Niederdruckraum an und dichtet somit den Füllkanal zuverlässig ab. Beim Ansteuern eines Aktors des Kraftstoffinjektors ergibt sich durch eine Bewegung des Kopplerkolbens in den Kopplerspaltraum hinein ein sofortiger Druckaufbau in dem Koppler, was - wie schon zuvor beschrieben - die Funktion des Kopplers verbessert.In a further embodiment of the invention, the diameter of the leaf spring valve is greater than the inner diameter of the coupler body in the region of the mouth of the filling channel in the coupler gap. Because of this slightly larger outer diameter of the leaf spring valve than the inner diameter of the coupler body and the radially resilient properties, the leaf spring valve is against the inner wall of the coupler body at a higher pressure in the coupler gap than in the low pressure chamber and thus reliably seals the filling channel. When an actuator of the fuel injector is actuated, a movement of the coupler piston into the coupler gap space results in an immediate buildup of pressure in the coupler, which, as described above, improves the function of the coupler.

In weiterer Ausgestaltung der Erfindung ist eine Sicherungseinrichtung zur Fixierung des Blattfederventils vorgesehen. Diese Sicherungseinrichtung ist allgemein so ausgebildet, dass das Blattfederventil sich weder radial als auch axial in Bezug zu der Mündung des Füllkanals insbesondere beim Betrieb des Kraftstoffinjektors verschieben kann. Dadurch ist sichergestellt, dass ein möglicher Ausfalls des Kopplers durch eine nicht mehr von dem Blattfederventil absperrbaren Füllkanal ausgeschlossen ist.In a further embodiment of the invention, a securing device for fixing the leaf spring valve is provided. This safety device is generally designed so that the leaf spring valve is neither radially nor axially in relation to the mouth of the filling channel in particular during operation of the fuel injector can move. This ensures that a possible failure of the coupler is excluded by a no longer be shut off by the leaf spring valve filling channel.

In Weiterbildung der Erfindung ist die Sicherungseinrichtung eine Verdrehsicherungseinrichtung. Eine solche Verdrehsicherungseinrichtung reicht normalerweise für einen störungsfreien Betrieb des Kopplers aus.In a further development of the invention, the securing device is an anti-rotation device. Such anti-rotation device is usually sufficient for trouble-free operation of the coupler.

In Weiterbildung der Erfindung ist die Verdrehsicherung eine in eine Haltenut des Kopplerkolben (oder auch des Kopplerkörpers) eingreifende Abkantung des Blattfederventils. Dadurch ist die verdrehgesicherte Fixierung des Blattfederventils sichergestellt. Weiterhin kann die Verdrehsicherung auch durch ein separates Bauteil in Form beispielsweise eines Bleches gebildet sein, das mit dem Kopplerkolben (beziehungsweise dem Kopplerkörper) zusammenwirkt, so dass sich das Blattfederventil nicht verdrehen kann.In a further development of the invention, the anti-rotation device is in a retaining groove of the coupler piston (or the coupler body) engaging the fold of the leaf spring valve. As a result, the rotationally secured fixation of the leaf spring valve is ensured. Furthermore, the rotation can also be formed by a separate component in the form of, for example, a metal sheet, which cooperates with the coupler piston (or the coupler body), so that the leaf spring valve can not rotate.

In Weiterbildung der Erfindung ist die Verdrehsicherungseinrichtung eine Nase, die mit einer Ausnehmung entweder in dem Kopplerkörper oder aber auch bei entsprechender Auslegung der Ausnehmung in dem Kopplerkolben zusammenwirkt.In a further development of the invention, the anti-rotation device is a nose which cooperates with a recess either in the coupler body or else with a corresponding design of the recess in the coupler piston.

In Weiterbildung der Erfindung ist der Werkstoff des Blattfederventils Federstahl. Dies ist der besonders geeignete Werkstoff zur Herstellung des Blattfederventils.In a further development of the invention, the material of the leaf spring valve spring steel. This is the most suitable material for producing the leaf spring valve.

Weitere vorteilhafte Ausgestaltungen der Erfindung sind der Zeichnungsbeschreibung zu entnehmen, in der ein in den Figuren dargestelltes Ausführungsbeispiel der Erfindung näher beschrieben ist.Further advantageous embodiments of the invention are described in the drawings, in which an illustrated in the figures embodiment of the invention is described in detail.

Es zeigen:

Figur 1
eine teilweise Schnittdarstellung eines Kraftstoffinjektors mit einem piezoelektrischen Aktuator und einem hydraulischen Koppler,
Figur 2
eine erste Schaltstellung eines Kopplers,
Figur 3
eine zweite Schaltstellung eines Kopplers,
Figur 4
eine dritte Schaltstellung eines Kopplers,
Figur 5
ein Diagramm zum Verlauf eines Injektornadelhubes eines Kraftstoffinjektors,
Figur 6
eine perspektivische Darstellung eines Kopplerkolbens mit einer Sicherungseinrichtung für ein Blattfederventil und
Figur 7
eine perspektivische Darstellung eines Kopplerkolbens mit einer Sicherungseinrichtung für ein Blattfederventil in einer weiteren Ausführungsform
Show it:
FIG. 1
a partial sectional view of a fuel injector with a piezoelectric actuator and a hydraulic coupler,
FIG. 2
a first switching position of a coupler,
FIG. 3
a second switching position of a coupler,
FIG. 4
a third switching position of a coupler,
FIG. 5
a diagram for the course of Injektornadelhubes a fuel injector,
FIG. 6
a perspective view of a coupler piston with a securing device for a leaf spring valve and
FIG. 7
a perspective view of a coupler piston with a securing device for a leaf spring valve in another embodiment

Figur 1 zeigt einen Kraftstoffinjektor 1 eines Common-Rail-Einspritzsystems zum Einspritzen von Kraftstoff in einen nicht gezeigten Brennraum einer Brennkraftmaschine. Eine Hochdruckpumpe 2 fördert Kraftstoff aus einem Tank 3 in einen Hochdruckspeicher 4. In dem Hochdruckspeicher 4 ist Kraftstoff, insbesondere Dieselkraftstoff unter einem hohen Druck von beispielsweise 2.000 bar oder mehr gespeichert. An dem Hochdruckspeicher 4 ist der Kraftstoffinjektor 1 neben weiteren, nicht gezeigten Kraftstoffinjektoren über eine Hochdruckleitung 5 angeschlossen. Die Hochdruckleitung 5 mündet in einen zu einem Hochdruckbereich des Kraftstoffinjektors 1 gehörenden, axialen Versorgungskanal 6, durch den Kraftstoff in einen Druckraum 7 strömt. Der Kraftstoff strömt bei einem Einspritzvorgang aus dem Druckraum 7 in axialer Richtung an einer Injektornadel 8 vorbei durch Einspritzbohrungen 16 in den Brennraum der Brennkraftmaschine. Der Kraftstoffinjektor 1 ist über einen Injektorrücklaufanschluss 9 an eine Rücklaufleitung 10 angeschlossen. Über die Rücklaufleitung 10 kann eine nachfolgend noch erläuterte Steuermenge an Kraftstoff von dem Kraftstoffinjektor 1 zu dem Tank 3 abfließen und von dort erneut dem Hochdruckkreislauf zugeführt werden. FIG. 1 shows a fuel injector 1 of a common rail injection system for injecting fuel into a combustion chamber, not shown, of an internal combustion engine. A high-pressure pump 2 conveys fuel from a tank 3 into a high-pressure accumulator 4. In the high-pressure accumulator 4, fuel, in particular diesel fuel, is stored under a high pressure of, for example, 2,000 bar or more. At the high pressure accumulator 4 of the fuel injector 1 is connected in addition to other, not shown fuel injectors via a high pressure line 5. The high-pressure line 5 opens into an axial supply channel 6 belonging to a high-pressure region of the fuel injector 1, through which fuel flows into a pressure chamber 7. During an injection process, the fuel flows from the pressure chamber 7 in the axial direction past an injector needle 8 through injection bores 16 into the combustion chamber of the internal combustion engine. The fuel injector 1 is connected via an injector return port 9 to a return line 10. Via the return line 10, a control quantity of fuel, which will be explained below, can flow away from the fuel injector 1 to the tank 3 and from there can again be supplied to the high-pressure circuit.

Die Injektornadel 8 ist innerhalb einer Stufenbohrung 11 eines Injektornadelkörpers 12 axial verstellbar geführt. Der Injektornadelkörper 12 ist im Verbund mit einer Drosselplatte und einem Ventilkörper gegen einen Haltekörper 13 mittels einer Spannmutter verspannt.The injector needle 8 is guided axially adjustable within a stepped bore 11 of an injector needle body 12. The injector needle body 12 is clamped in conjunction with a throttle plate and a valve body against a holding body 13 by means of a clamping nut.

Die Injektornadel 8 weist an ihrer Nadelspitze 15 eine als Dichtfläche ausgebildete Schließfläche auf, mit der die Injektornadel 8 in eine dichte Anlage an einen innerhalb des Injektornadelkörpers 12 ausgebildeten Injektornadelkörpersitz anbringbar ist. Wenn die Injektornadel 8 an dem Injektornadelkörpersitz anliegt, sich also in der Schließstellung befindet, ist der Kraftstoffaustritt aus der zumindest einen Einspritzbohrung 16 gesperrt. Ist die Injektornadel 8 dagegen von dem Injektornadelkörpersitz abgehoben, kann Kraftstoff aus dem Druckraum 7, der zumindest annähernd unter dem Druck des Kraftstoffs in dem Hochdruckspeicher 4 steht, in den Brennraum strömen.The Injektornadel 8 has at its needle tip 15 designed as a sealing surface closing surface with which the Injektornadel 8 is mounted in a tight contact with a trained within the Injektornadelkörpers 12 Injektornadelkörpersitz. If the Injektornadel 8 rests against the Injektornadelkörpersitz, so is in the closed position, the fuel outlet from the at least one injection hole 16 is locked. By contrast, if the injector needle 8 is lifted off the injector needle body seat, fuel can flow from the pressure chamber 7, which is at least approximately under the pressure of the fuel in the high-pressure accumulator 4, into the combustion chamber.

Von einer in der Zeichnungsebene oberen Stirnseite der Injektornadel 8 wird eine Steuerkammer 17 begrenzt, die über eine Zulaufdrossel 18 mit unter Hochdruck stehendem Kraftstoff aus dem Versorgungskanal 6 versorgt wird. Gleichzeitig wird ein Druckraum 14, aus dem Kraftstoff bei geöffneter Injektornadel 8 in den Brennraum strömen kann, mit Kraftstoff aus dem Versorgungskanal 6 versorgt. Der Druckraum 14 umschließt dabei einen die Steuerkammer 17 begrenzenden, federkraftbeaufschlagten Hülsenkörper 32 radial außen. Die in dem Hülsenkörper 32 ausgebildete Steuerkammer 17 ist über eine Ablaufdrossel 19 mit einer Steuerventilkammer 20 verbunden, die mittels eines axial verstellbaren Steuerventilelements 21 mit einem Niederdruckraum 22 und damit mit dem Injektorrücklaufanschluss 9 verbindbar ist. Das Steuerventilelement 21 ist Teil eines normalerweise als 3/2-Wegeventil ausgebildeten Steuerventils 23. Bei in einer ersten (unteren) Schaltstellung befindlichem Steuerventilelement 21 kann Kraftstoff aus der Steuerkammer 17 über die Ablaufdrossel 19 und die Steuerventilkammer 20 in dem Niederdruckraum 22 zu dem Injektorrücklaufanschluss 9 strömen. Gleichzeitig ist ein aus dem Druckraum 14 ausmündender und in die Steuerventilkammer 20 einmündender Bypass 35 von dem Steuerventilelement 21 gesperrt. Bei in einer zweiten (oberen) Schaltstellung befindlichem Steuerventilelement 21 ist die Verbindung zwischen der Steuerventilkammer 20 und dem Niederdruckraum 22 gesperrt und der Bypass 35 ist freigegeben, so dass die Steuerkammer 17 über den Bypass 35, die Steuerventilkammer 20, die Ablaufdrossel 19 und die Zulaufdrossel 18 schnell auf Hochdruck gebracht wird.From a plane in the drawing upper side of the Injektornadel 8 a control chamber 17 is limited, which is supplied via an inlet throttle 18 with fuel under high pressure from the supply channel 6. At the same time, a pressure chamber 14, from which fuel can flow into the combustion chamber when the injector needle 8 is open, is supplied with fuel from the supply channel 6. The pressure chamber 14 encloses a control chamber 17 limiting, spring-loaded sleeve body 32 radially outward. The formed in the sleeve body 32 control chamber 17 is connected via an outlet throttle 19 with a control valve chamber 20 which is connected by means of an axially adjustable control valve element 21 with a low-pressure chamber 22 and thus with the injector return port 9. The control valve element 21 is part of a normally designed as a 3/2-way valve control valve 23. In a first (lower) switching position befindliches control valve element 21, fuel from the control chamber 17 via the outlet throttle 19 and the control valve chamber 20 in the low pressure chamber 22 to the injector return port stream. At the same time, a bypass 35 opening out of the pressure chamber 14 and opening into the control valve chamber 20 is blocked by the control valve element 21. When in a second (upper) switching position befindliches control valve element 21, the connection between the control valve chamber 20 and the low-pressure chamber 22 is locked and the bypass 35 is released, so that the control chamber 17 via the bypass 35, the control valve chamber 20, the outlet throttle 19 and the inlet throttle 18 is brought quickly to high pressure.

Zum Verstellen des kolbenförmigen Steuerventilelements 21 ist ein piezoelektrischer Aktor 24 vorgesehen, der über einen hydraulischen Koppler 25 mit dem Steuerventilelement 21 gekoppelt ist. Bei einer alternativen nicht gezeigten Ausführungsform kann das Steuerventil 23 unmittelbar von dem hydraulischen Koppler 25, genauer von einem nachfolgend noch erläuterten Arbeitskolben 28 des hydraulischen Kopplers 25 betätigt werden. Zum Öffnen des Steuerventils, also zum Bewegen des Steuerventilelements 21 in der Zeichnungsebene nach unten, weg von seinem oberen Steuerventilsitz 26, wird der piezoelektrische Aktor 24 bestromt und dehnt sich aus. Hierdurch wird ein in der Zeichnungsebene oberer, beweglicher Kopplerkolben 27 des hydraulischen Kopplers, der über einen Kopplerspaltraum 29 mit dem Kopplerkolben 27 hydraulisch gekoppelt ist, in der Zeichnungsebene nach unten bewegt. Der Arbeitskolben 28 drückt auf das Steuerventilelement 21, welches in der Folge entgegen der Kraft einer Steuerschließfeder 30 von seinem oberen Steuerventilsitz 26 wegbewegt wird und somit den Kraftstofffluss aus der Steuerkammer 17 hin zu dem Injektorrücklaufanschluss freigibt und gleichzeitig den Bypass 35 sperrt. Durch die Abstimmung der Durchflussquerschnitte sinkt der Druck in der Steuerkammer 17 rapide ab, wodurch die Injektornadel 8 von ihrem Injektornadelkörpersitz abhebt, so dass Kraftstoff aus dem Druckraum 7 durch die Einspritzbohrung 16 ausströmen kann.For adjusting the piston-shaped control valve element 21, a piezoelectric actuator 24 is provided, which is coupled via a hydraulic coupler 25 with the control valve element 21. In an alternative embodiment, not shown, the control valve 23 can be actuated directly by the hydraulic coupler 25, more precisely by a working piston 28 of the hydraulic coupler 25 which will be explained below. To open the control valve, so for moving the control valve member 21 in the plane of the drawing down, away from its upper control valve seat 26, the piezoelectric actuator 24 is energized and expands. As a result, an upper in the plane of the drawing, movable coupler piston 27 of the hydraulic coupler, which is hydraulically coupled via a coupler gap 29 with the coupler piston 27, moves in the drawing plane down. The working piston 28 presses on the control valve element 21, which is moved away in the sequence counter to the force of a control closing spring 30 from its upper control valve seat 26 and thus releases the flow of fuel from the control chamber 17 to the injector return port while blocking the bypass 35. By adjusting the flow cross-sections of the pressure in the control chamber 17 decreases rapidly, whereby the injector needle 8 lifts from her Injektornadelkörpersitz so that fuel can flow out of the pressure chamber 7 through the injection hole 16.

Zum Beenden des Einspritzvorgangs wird die Bestromung des piezoelektrischen Aktors 24 beendet, wodurch sich der Piezokristallstapel des Aktors 24 zusammenzieht und der Kopplerkolben 27 unterstützt durch die Federkraft einer Rohrfeder 38 in der Zeichnungsebene nach oben bewegt wird. Der Arbeitskolben 28 drückt unterstützt durch die Steuerschließfeder 30 in der Zeichnungsebene nach unten gegen das Steuerventilelement 21. Zwischen dem Arbeitskolben 28 und dem Steuerventilelement 21 ist somit ein ständiger Kontakt gewährleistet. Der Arbeitskolben 28 und das Steuerventilelement 21 werden bei nicht bestromtem Aktor 24 nach oben in die obere Schaltstellung bewegt, in der das Steuerventilelement 21 an seinem oberen Steuerventilsitz 26 anliegt und die hydraulische Verbindung aus der Steuerkammer 17 zum Injektorrücklaufanschluss 9 sperrt. Der durch die Zulaufdrossel 18 sowie über den Bypass 35 in die Steuerkammer 17 nachströmende Kraftstoff sorgt für eine schnelle Druckerhöhung in der Steuerkammer 17 und für eine auf die Injektornadel 8 wirkende hydraulische Schließkraft. Die daraus resultierende Schließbewegung der Injektornadel 8 wird von einer Schließfeder 31 unterstützt, die sich mit einem Ende an der Injektornadel 8 und mit dem zweiten Ende an einem die Steuerkammer 17 begrenzenden Hülsenkörper 32 abstützt.To end the injection process, the energization of the piezoelectric actuator 24 is terminated, whereby the piezocrystal stack of the actuator 24 contracts and the coupler piston 27 is supported by the spring force of a Bourdon tube 38 in the drawing plane moves upward. The working piston 28 presses supported by the control closing spring 30 in the plane of the drawing down against the control valve element 21. Between the working piston 28 and the control valve element 21 thus a permanent contact is ensured. The working piston 28 and the control valve element 21 are moved at not energized actuator 24 upwards into the upper switching position in which the control valve element 21 rests against its upper control valve seat 26 and the hydraulic connection from the control chamber 17 to Injector return port 9 locks. The fuel flowing in through the inlet throttle 18 and via the bypass 35 into the control chamber 17 ensures a rapid pressure increase in the control chamber 17 and a hydraulic closing force acting on the injector needle 8. The resulting closing movement of the Injektornadel 8 is supported by a closing spring 31 which is supported at one end to the Injektornadel 8 and the second end to a control chamber 17 limiting sleeve body 32.

Die folgenden Figuren 2 bis 4 zeigen die detaillierte Ausgestaltung des Kopplers 25 mit den in einer Stufenausnehmung 34 in einem Kopplerkörper 33 angeordneten Kopplerkolben 27 und Arbeitskolben 28 in verschiedenen Schaltstellungen. Der Kopplerkolben 27 hat einen größeren Außendurchmesser als der Arbeitskolben 28 und ist folglich in der Stufenausnehmung 34 mit dem größeren Innendurchmesser angeordnet. Der Kopplerkolben 27 kann aber auch einen gleichen oder kleineren Durchmesser als der Arbeitskolben 28 aufweisen. Zwischen dem Kopplerkolben 27 und dem Arbeitskolben 28 ist der schon erwähnte Kopplerspaltraum 29 angeordnet, der zur Übertragung einer von dem Kopplerkolben 27 ausgeführten Axialbewegung auf den Arbeitskolben 28 mit Hydraulikfluid in Form von Kraftstoff gefüllt sein muss. Hierauf wird nachfolgend noch eingegangen. Der Kopplerkolben 27 ragt mit einem betätigungsseitigen Ende, an dem eine Betätigungsplatte 36 angeordnet ist, aus dem Kopplerkörper 33 hinaus und wirkt mittels der Betätigungsplatte 36 mit dem Aktor 24 zusammen. Auf der gegenüberliegenden Seite weist der Arbeitskolben 33 eine Betätigungsnase 37 auf, die - wie zuvor beschrieben - das Steuerventilelement 21 aus dem Steuerventilsitz 26 nach unten (Figur 1) drücken kann.The following FIGS. 2 to 4 show the detailed configuration of the coupler 25 with the arranged in a stepped recess 34 in a coupler body 33 coupler piston 27 and working piston 28 in different switching positions. The coupler piston 27 has a larger outer diameter than the working piston 28 and is thus arranged in the stepped recess 34 with the larger inner diameter. However, the coupler piston 27 may also have a same or smaller diameter than the working piston 28. Between the coupler piston 27 and the piston 28 of the already mentioned Kopplerspaltraum 29 is arranged, which must be filled to transfer an executed by the coupler piston 27 axial movement of the piston 28 with hydraulic fluid in the form of fuel. This will be discussed below. The coupler piston 27 protrudes with an actuation-side end, on which an actuation plate 36 is arranged, out of the coupler body 33 and cooperates with the actuator 24 by means of the actuation plate 36. On the opposite side, the working piston 33 has an actuating nose 37, which - as described above - the control valve element 21 from the control valve seat 26 down ( FIG. 1 ) can press.

Zur Einstellung einer definierten Ausgangsruhelage und zur Aktorvorspannung weist der Koppler 25 eine Rohrfeder 38 auf, die sich am einem unteren Ringabsatz 39 des Kopplerkörpers 33 und der Betätigungsplatte 36 abstützt und beide Bauteile auseinanderdrückt. Gleichzeitig ist an dem Arbeitskolben 28 ein Haltering für eine Arbeitskolbenfeder 40 angeordnet, die den Arbeitskolben 28 nach unten aus dem Kopplerkörper 33 bis zur Anlage der Betätigungsnase 37 an dem Steuerventilelement 21 drückt. Zur Befüllung beziehungsweise zum Nachfüllen des Kopplerspaltraums 29 mit Kraftstoff aus dem den Koppler 25 umgebenden Niederdruckraum 22 ist vorzugsweise ein Füllkanal 41 in die Wandung des Kopplerkörpers 33 eingelassen. Der Füllkanal 41 ist im Bereich einer Mündung in dem Kopplerspaltraum 29 von einem in Richtung des Kopplerspaltraums 29 öffnenden einteiligem und elastisch verformbaren Ventil in Form einer als geschlitzte Hülse ausgebildeten Blattfederventil 42 verschlossen. Das Blattfederventil 42 weist einen etwas größeren Außendurchmesser als der Innendurchmesser des Kopplerkörpers 33 beziehungsweise der Stufenausnehmung 34 auf. Aufgrund des etwas größeren Außendurchmessers des Blattfederventils 42 und der radial federnden Eigenschaften liegt das Blattfederventil 42 an der Stufenausnehmung 34 an und dichtet die hydraulische Verbindung durch den Füllkanal 41 ab. Das Ventil ist geschlossen (Figur 2). Das Blattfederventil 42 ist im Bereich eines Stufenabsatzes 43 des Kopplerkolbens 27 angeordnet, was platzsparend ist und keine Auswirkungen auf die Funktion des Kopplers 25 hat. Bezüglich der Anordnung des Blattfederventils 42 sind aber auch andere Lösungen denkbar.To set a defined Ausgangsruhelage and Aktorvorspannung, the coupler 25 has a Bourdon tube 38 which is supported on a lower annular shoulder 39 of the coupler body 33 and the actuator plate 36 and presses apart the two components. At the same time, a retaining ring for a working piston spring 40 is arranged on the working piston 28, which presses the working piston 28 down from the coupler body 33 to the abutment of the actuating lug 37 on the control valve element 21. For filling or for refilling the Kopplerspaltraums 29 with fuel from the coupler 25 surrounding low-pressure space 22 is preferably a filling channel 41 in the Wall of the coupler body 33 inserted. The filling channel 41 is closed in the region of an orifice in the coupler gap 29 by a one-piece and elastically deformable valve opening in the direction of the coupler gap 29 in the form of a leaf-spring valve 42 designed as a slotted sleeve. The leaf spring valve 42 has a slightly larger outer diameter than the inner diameter of the coupler body 33 and the step recess 34. Due to the slightly larger outer diameter of the leaf spring valve 42 and the radially resilient properties of the leaf spring valve 42 abuts the stepped recess 34 and seals the hydraulic connection through the filling channel 41 from. The valve is closed ( FIG. 2 ). The leaf spring valve 42 is arranged in the region of a stepped shoulder 43 of the coupler piston 27, which saves space and has no effect on the function of the coupler 25. With regard to the arrangement of the leaf spring valve 42 but other solutions are conceivable.

Beim Ansteuern des Aktors 24 ergibt sich durch die Bewegung des Kopplerkolbens 27 in den Kopplerspaltraum 29 ein Druckaufbau im Koppler 25, der auf den Arbeitskolben 28 übertragen wird (Figur 3). Durch die genaue Passform des Blattfederventils 42 wird der Kopplerspaltraum 29 nur sehr wenig vergrößert, weshalb eine genaue Ausführung der Kopplerfunktion gewährleistet ist.When the actuator 24 is actuated, the movement of the coupler piston 27 into the coupler gap 29 results in a pressure build-up in the coupler 25, which is transmitted to the working piston 28 (FIG. FIG. 3 ). Due to the exact fit of the leaf spring valve 42, the coupler gap space 29 is increased only very slightly, which is why an exact execution of the coupler function is ensured.

In den Einspritzpausen ist der Druck in dem Niederdruckraum 22 größer beziehungsweise höher als in dem Kopplerspaltraum 29, weshalb das Blattfederventil 42 durch den Druck in dem Füllkanal 41 von der Innenwand im Bereich der Stufenausnehmung 34 weggedrückt wird und die hydraulische Verbindung zwischen dem Niederdruckraum 22 und dem Kopplerspaltraum 29 freigibt. Ergebnis ist eine sehr schnelle Wiederbefüllung zwischen Einspritzvorgängen beziehungsweise Teileinspritzvorgängen des Kraftstoffinjektors 1 mit quasi konstanter nicht nachlassender Kopplerfunktion. Dies ist in dem Diagramm in Figur 5 dargestellt, wobei in dem Diagramm der resultierende Nadelhub Nh von aufeinander folgenden Einspritzungen eines Kraftstoffinjektors 1wiedergegeben ist. Dabei ist mit einer ausgezogenen Linie der Nadelhub Nh eines konventionellen Koppler 25 und mit einer strichlinierten Linie der Nadelhub Nh eines erfindungsgemäßen Kopplers 25 dargestellt.In the injection pauses, the pressure in the low pressure chamber 22 is greater or higher than in the coupler gap 29, which is why the leaf spring valve 42 is pushed away by the pressure in the filling channel 41 of the inner wall in the region of the Stufenausnehmung 34 and the hydraulic connection between the low pressure chamber 22 and the Coupler gap 29 releases. The result is a very rapid refilling between injection processes or partial injection processes of the fuel injector 1 with a quasi-constant, non-decreasing coupler function. This is in the diagram in FIG. 5 in the diagram, the resulting needle lift Nh of successive injections of a fuel injector 1 is shown. In this case, the needle stroke Nh of a conventional coupler 25 is shown with a solid line and the needle stroke Nh of a coupler 25 according to the invention is shown with a dashed line.

Erkennbar ist, dass bei der zweiten Einspritzung der Nadelhub Nh der Injektornadel 8 mit den konventionellen Koppler 25 deutlich geringer als bei der ersten Einspritzung ist. Dagegen zeigt der strichlinierte Nadelhub Nh, der durch die erfindungsgemäße Ausgestaltung darstellbar ist, keinen Abbau.It can be seen that in the second injection the needle stroke Nh of the injector needle 8 with the conventional coupler 25 is significantly lower than in the first injection. In contrast, the dashed Nadelhub Nh, which can be represented by the inventive design, no degradation.

Figur 6 zeigt einen grundsätzlich gleichen Aufbau des Kopplers 25 mit einem Kopplerkolben 27, wie der zuvor beschrieben worden ist. Zusätzlich ist hier eine Sicherungseinrichtung 44 vorgesehen, die sicherstellt, dass das Blattfederventil 42 sich insbesondere nicht verdreht und somit mit einem Schlitz 45 (der geschlitzten Hülse) in den Bereich der Mündung des Füllkanals 41 gelangt. In einem solchen Fall wäre die Funktion des Blattfederventils 42 nicht sichergestellt. Die Sicherungseinrichtung 44 ist als ein abgewinkeltes Blech ausgebildet, das an dem Stufenabsatz 43 des Kopplerkolbens 27 in geeigneter Weise verklemmt ist. FIG. 6 shows a basically same construction of the coupler 25 with a coupler piston 27, as has been previously described. In addition, a securing device 44 is provided here, which ensures that the leaf spring valve 42 in particular does not rotate and thus reaches the region of the mouth of the filling channel 41 with a slot 45 (the slotted sleeve). In such a case, the function of the leaf spring valve 42 would not be ensured. The securing device 44 is formed as an angled sheet, which is clamped to the stepped shoulder 43 of the coupler piston 27 in a suitable manner.

Alternativ kann die Sicherungseinrichtung 44a auch durch eine Abkantung 46 des Blattfederventils 42 an einem an den Schlitz 45 angrenzenden Ende ausgebildet sein. Die Abkantung 46, die auch ein mit dem Blattfederventil 42 verbundenes, beispielsweise verschweißtes, Teil sein kann, greift in eine Haltenut 47 in dem Kopplerkolben 27 ein. Alternativ kann die Sicherungseinrichtung auch eine Nase sein, die in eine entsprechende Vertiefung in den Kopplerkolben 27 eingreift. Grundsätzlich kann die Verdrehsicherung des Blattfederventils 42 auch gegenüber dem Kopplerkörper 33 erfolgen.Alternatively, the securing device 44a may also be formed by a fold 46 of the leaf spring valve 42 at an end adjoining the slot 45. The fold 46, which may also be connected to the leaf spring valve 42, for example, welded, part engages in a retaining groove 47 in the coupler piston 27 a. Alternatively, the securing device may also be a nose, which engages in a corresponding depression in the coupler piston 27. Basically, the rotation of the leaf spring valve 42 can also take place relative to the coupler body 33.

Abschließend wird darauf hingewiesen, dass beliebige zuvor beschriebene Einzelmerkmale des Erfindungsgenstandes miteinander und untereinander kombiniert sein können.Finally, it is pointed out that any individual features of the subject invention described above can be combined with each other and with each other.

Claims (9)

  1. Fuel injector (1) of a fuel injection system of an internal combustion engine, wherein the fuel injector (1) has a hydraulic coupler (25), which hydraulic coupler has a coupler piston (27) movable in a coupler body (33) and has a working piston (28) coupled to said coupler piston via a coupler gap chamber (29) and likewise movable in the coupler body (33), and wherein the coupler gap chamber (29) is connected via at least one filling channel (41) to a low-pressure chamber (22) arranged outside the coupler body (33),
    characterized in that, in the region of a connection of the filling channel (41) to the coupler gap chamber (29), there is arranged a unipartite and elastically deformable valve which opens in the direction of the coupler gap chamber (29) and which is formed as an axially slotted sleeve.
  2. Fuel injector (1) according to Claim 1,
    characterized in that the valve is a leaf spring valve (42).
  3. Fuel injector (1) according to Claim 2,
    characterized in that the outer diameter of the leaf spring valve (42) is greater than the inner diameter of the coupler body (33) in the region in which the filling channel (41) opens into the coupler gap chamber (29).
  4. Fuel injector (1) according to one of Claims 2 and 3,
    characterized in that a securing device (44, 44a) is provided for fixing the leaf spring valve (42).
  5. Fuel injector (1) according to Claim 4,
    characterized in that the securing device (44, 44a) is a rotation-preventing securing device.
  6. Fuel injector (1) according to Claim 5,
    characterized in that the securing device (44) is an angled portion (46), which engages into a holding groove (47) of the coupler piston (27), of the leaf spring valve (42).
  7. Fuel injector (1) according to Claim 5,
    characterized in that the securing device (44a) is a metal sheet which interacts with a step shoulder (43) of the coupler piston (27).
  8. Fuel injector (1) according to Claim 5,
    characterized in that the rotation-preventing securing device is a lug.
  9. Fuel injector (1) according to one of the preceding claims,
    characterized in that the material of the leaf spring valve (42) is spring steel.
EP16197784.8A 2015-12-22 2016-11-08 Fuel injector Active EP3184803B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102015226576.5A DE102015226576A1 (en) 2015-12-22 2015-12-22 fuel injector

Publications (2)

Publication Number Publication Date
EP3184803A1 EP3184803A1 (en) 2017-06-28
EP3184803B1 true EP3184803B1 (en) 2018-10-03

Family

ID=57256160

Family Applications (1)

Application Number Title Priority Date Filing Date
EP16197784.8A Active EP3184803B1 (en) 2015-12-22 2016-11-08 Fuel injector

Country Status (2)

Country Link
EP (1) EP3184803B1 (en)
DE (1) DE102015226576A1 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10101800A1 (en) * 2001-01-17 2002-07-18 Bosch Gmbh Robert Fluid control valve e.g. for common rail injector of motor vehicle combustion engine, has size of pressure pin set by amount of pressurized fluid flowing via return channel
DE10333699A1 (en) * 2003-07-24 2005-03-03 Robert Bosch Gmbh Fuel injection device for internal combustion engine has one hydraulic coupler piston connected to actuator by piston rod, other piston operates control valve via narrower rod, control valve is at least partly force-balanced
DE102009001266A1 (en) 2009-03-02 2010-09-09 Robert Bosch Gmbh Fuel injector with piezoelectric actuator and hydraulic coupler

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Also Published As

Publication number Publication date
EP3184803A1 (en) 2017-06-28
DE102015226576A1 (en) 2017-06-22

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