EP3921536B1 - Injector unit for the injection of fuel, and method for the operation of an injector unit of this type - Google Patents

Injector unit for the injection of fuel, and method for the operation of an injector unit of this type Download PDF

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Publication number
EP3921536B1
EP3921536B1 EP20705636.7A EP20705636A EP3921536B1 EP 3921536 B1 EP3921536 B1 EP 3921536B1 EP 20705636 A EP20705636 A EP 20705636A EP 3921536 B1 EP3921536 B1 EP 3921536B1
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EP
European Patent Office
Prior art keywords
seat plate
control signal
electromagnet
armature element
armature
Prior art date
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Application number
EP20705636.7A
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German (de)
French (fr)
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EP3921536A1 (en
Inventor
Richard Pirkl
Razvan-Sorin STINGHE
Martin Seidl
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Liebherr Components Deggendorf GmbH
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Liebherr Components Deggendorf GmbH
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Publication of EP3921536A1 publication Critical patent/EP3921536A1/en
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00Other 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
    • F02M63/0012Valves
    • F02M63/0014Valves characterised by the valve actuating means
    • F02M63/0015Valves characterised by the valve actuating means electrical, e.g. using solenoid
    • F02M63/0017Valves characterised by the valve actuating means electrical, e.g. using solenoid using electromagnetic operating means
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/20Output circuits, e.g. for controlling currents in command coils
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M47/00Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
    • F02M47/02Fuel-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
    • F02M47/027Electrically actuated valves draining the chamber to release the closing pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02MSUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M63/00Other 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
    • F02M63/0012Valves
    • F02M63/007Details not provided for in, or of interest apart from, the apparatus of the groups F02M63/0014 - F02M63/0059
    • F02M63/0075Stop members in valves, e.g. plates or disks limiting the movement of armature, valve or spring
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/20Output circuits, e.g. for controlling currents in command coils
    • F02D2041/202Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2024Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit the control switching a load after time-on and time-off pulses
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/20Output circuits, e.g. for controlling currents in command coils
    • F02D2041/202Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2037Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit for preventing bouncing of the valve needle
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02DCONTROLLING COMBUSTION ENGINES
    • F02D41/00Electrical control of supply of combustible mixture or its constituents
    • F02D41/20Output circuits, e.g. for controlling currents in command coils
    • F02D2041/202Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
    • F02D2041/2058Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit using information of the actual current value

Definitions

  • the present invention relates to an injector unit for injecting fuel and a method for operating such an injector unit.
  • fuel is usually injected into a combustion chamber via an injector in a specific quantity and for a specific period of time. Due to the very short injection durations, which are in the microsecond range, it is necessary to open and close the outlet opening of the injector at a very high frequency.
  • An injector typically has a nozzle needle (also: injector needle), which allows high-pressure fuel to escape when at least one outlet hole of the injector is released.
  • a nozzle needle also: injector needle
  • injector needle allows high-pressure fuel to escape when at least one outlet hole of the injector is released.
  • the nozzle needle acts like a plug, which allows the fuel to escape when it is raised. It is therefore necessary to lift this needle at relatively short intervals and to allow it to slide back into the outlet opening after a short time. Hydraulic servo valves can be used to trigger this movement. Such valves, in turn, are controlled with the help of an electromagnet.
  • servo valves which control the nozzle needle and are themselves controlled by an electromagnetic valve.
  • a control chamber that interacts with the nozzle needle, a pressure level is built up with the help of the fuel available under high pressure, which acts on the nozzle needle in the closing direction.
  • This control chamber is typically connected to the high-pressure area of the fuel via a supply line.
  • this control chamber also: lower control chamber
  • has a line to a valve chamber also: upper control chamber
  • a closable outlet throttle also through opening
  • seat plate is used here in the sense of a throttle plate or sealing plate. If it does this, the pressure in the valve chamber and the control chamber drops, which reduces the closing force acting on the nozzle needle, since the high-pressure fuel in the valve chamber and the control chamber can flow out. This causes a movement of the nozzle needle, which opens the outlet opening at the injector tip.
  • the outlet throttle in the seat plate of the injector is optionally closed or opened with the help of an anchor element.
  • the high-pressure fuel flows into a low-pressure area via the through-opening of the seat plate. This results in a pressure drop not only in the valve chamber, but - due to the line connecting the valve chamber and the control chamber - also in the control chamber adjacent to the nozzle needle.
  • the reduction in pressure in the control chamber results in the nozzle needle being raised from its nozzle seat and fuel being dispensed from the injector.
  • armature bouncing leads to wear on the armature and the stop that abuts against it, which can lead to premature replacement of one of the two components.
  • the injector unit for injecting fuel comprises, among other things, a seat plate with a through-opening that extends through the seat plate, an anchor element that can be placed on the seat plate to close the through-opening, a spring element that urges the anchor element towards the seat plate to close the through-opening, an electromagnet that is designed to apply a force to the anchor element in order to lift the anchor element off the seat plate, and a stop for limiting a stroke of the anchor element in a state lifted off the seat plate.
  • the injector unit is characterized by a control unit that is designed to reduce a control signal of the electromagnet for lifting the anchor element off the seat plate before the Anchor element contacts the stop for the first time after lifting off the seat plate.
  • control signal is the current signal that flows through a coil of the electromagnet.
  • the through opening connects the two flat sides of the seat plate with one another and the anchor placed on the seat plate hydraulically seals the through opening. Furthermore, the through opening can be a drain throttle which connects a space arranged below the seat plate with a space arranged above the seat plate.
  • the magnetic force acting on it must first overcome the spring force acting in the opposite direction and any frictional forces.
  • the attractive magnetic force increases steadily as the distance between the anchor element and the magnet decreases and the anchor element is increasingly accelerated until the anchor element is abruptly braked by the stop.
  • the control unit is designed to interrupt the control signal at least once during the pull of the armature in the direction of the magnet.
  • the attractive magnetic force is temporarily reduced to a very great extent.
  • the interruption advantageously takes place in such a way that the armature subsequently moves due to the forces acting on it so that it hits the stop at zero speed or at least at a very low speed. This completely prevents the bouncing or at least greatly reduces it.
  • control unit is designed to reduce the control signal of the electromagnet by more than 50%, preferably more than 75% and preferably more than 90% of an initial value at the beginning of the lifting process.
  • control unit is designed to increase the control signal again after reducing the control signal of the electromagnet, preferably to a range of at least 50%, preferably of at least 75% and most preferably of at least 90% of an initial value at the beginning of the lifting process.
  • the control signal which controls the magnetic attraction of the anchor element, can only drop sharply for a short moment and shortly afterwards move back to or close to the initial level.
  • This brief drop in the control signal causes the armature to be moved away from the through opening despite the brief drop in the drive signal.
  • the short-term drop in the control signal can be dimensioned such that after the anchor element has been lifted off the through-opening, the anchor element does not move closer in the direction of the through-opening.
  • the speed of the anchor element can decrease until it comes to a standstill Anchor element, but this preferably does not result in the anchor element approaching in the direction of the through opening.
  • control signal developed in this way ensures that the undesirable armature bounce at the stop is reduced and a particularly precise injection quantity control of the injector is achieved.
  • control unit is designed to raise the control signal of the electromagnet again after the anchor element has contacted the stop for the first time after being lifted off the seat plate, and/or when the stroke of the anchor element reaches a reversal point or is close to the reversal point in time.
  • a point in time for raising the control signal from the reduced level can be selected depending on the position of the armature element.
  • control unit is designed to transmit the control signal in a binary manner, i.e. only the control signal states on and off.
  • the control signal can only assume two states, namely on and off.
  • control signal is deactivated or temporarily deactivated after an on period. This leads to an overall more advantageous lifting process that has less armature bounce.
  • the seat plate is designed to separate a low-pressure area and a high-pressure area of the fuel when the through-throttle is closed.
  • the space provided for carrying out the stroke of the anchor element is filled with a fluid, preferably the fuel.
  • the fluid is not or only weakly magnetizable.
  • an anchor guide can be provided for guiding the anchor element during a lifting process, which preferably extends from the seat plate in the direction of the stop. This guide serves for the targeted placement or lifting of the anchor element from the through opening of the seat plate.
  • the electromagnet has a magnetic core and a coil which partially or completely accommodates the magnetic core.
  • the stop can be an end face of the electromagnet or also an end face of a magnetic core of the electromagnet.
  • the invention also includes the case that the stop is not part of the electromagnet.
  • the stop is provided inside the spring element designed as a spiral spring, so that the spiral spring winds around the stop.
  • the invention also relates to a method for operating an injector unit for injecting fuel, which is preferably designed according to one of the preceding variants, wherein in the method, among other things, an anchor element is moved from a seat plate against a spring force exerted by a spring in the direction of the seat plate by means of an electromagnet picked up to release a through opening in the seat plate.
  • the method is characterized in that the control signal of the electromagnet, which causes the anchor element to be lifted off the seat plate, is reduced before the anchor element contacts a stop limiting the stroke of the anchor element for the first time after it has been lifted off the seat plate.
  • control signal of the electromagnet is reduced by more than 50%, preferably more than 75% and preferably more than 90% from an initial value at the beginning of the lifting process.
  • control signal of the electromagnet after reducing the control signal of the electromagnet, the control signal is increased again, preferably to a range of at least 50%, preferably of at least 75% and most preferably of at least 90% of an initial value at the beginning of the lifting process.
  • control signal of the electromagnet is raised again after the anchor element has contacted the stop for the first time after being lifted off the seat plate, and/or when the stroke of the anchor element reaches a reversal point or is close to its reversal point.
  • control signal is of a binary nature, i.e. only the control signal states on and off are transmitted to the electromagnet.
  • Fig. 1 shows two diagrams arranged one above the other over time t, the upper of the two diagrams showing the course of a control signal I or the current supplied to the electromagnet according to the invention (solid line A) and according to the prior art (dashed line B). .
  • the diagram below shows the movement (x) of the anchor element as a function of the various control signals, with the dashed line representing the control behavior according to the prior art and the solid line representing the control according to the invention.
  • the current signal I for controlling the electromagnet is set to a value I 1 that is different from zero and causes the anchor element to be moved from the seat plate in the direction of a stroke-limiting stop, the anchor element initially moves slowly and then at ever faster speed in the direction of the stop (see dashed line B).
  • the attractive magnetic force increases steadily as the distance between the armature and the electromagnet decreases and the armature element is increasingly accelerated until the armature element is abruptly braked by a stop (X stop ). This results in a pronounced bouncing behavior of the anchor at the stop.
  • the bouncing has a negative effect on the adjustability of the solenoid valve as well as the feedback on the hydraulic switching behavior and increases wear on the magnet and the anchor element.
  • the armature element After bouncing has ended, the armature element remains at its stop in the position away from the through hole until the control signal I 1 is switched off at time t 3 .
  • the current flow through the coil is then completely reduced and the magnetic field is restored, with part of the magnetic field remaining for a short time due to remanence effects and eddy current influences.
  • the armature As soon as the decreasing magnetic force no longer overcomes the spring force, the armature is pressed back onto the seat plate by the spring.
  • the problem here is the bouncing at the maximum deflection of the anchor element at the distance X stop .
  • control signal With an improved control signal according to the invention, the bouncing of the armature at the stop X stop , which is spaced from the seat plate, should be prevented or at least greatly reduced.
  • the control signal is interrupted or reduced at least once while the armature is being pulled in the direction of the stop or the magnet.
  • control signal is reduced before the anchor element comes into contact with the stop, or as in Fig. 1 shown to reset to zero.
  • the attractive magnetic force is temporarily greatly reduced, so that the armature then moves due to the forces acting on it in such a way that it hits the upper stop at zero speed or at least at very low speed. This completely prevents bouncing or at least greatly reduces it.
  • control signal is activated again (last control signal activation at time t 2 ) as soon as the armature hits the second stop at zero or close to zero speed, so that the armature is held in the stop until the control signal is finally terminated (time ts).
  • the invention also covers the case where the armature either does not reach the stop or does so at a speed greater than zero.
  • the control signal is then advantageously activated again in a time range in which the armature speed is close to zero (time ts). The bouncing cannot be completely suppressed in this case, but is significantly reduced compared to conventional control.
  • the control signal is deactivated at time t 3 , whereby the anchor element is pushed by the spring element in the direction of the seat plate and there - similar to the stop spaced from the seat plate in a Current supply to the electromagnet according to the state of the art - bounces.
  • Fig.2 shows an enlarged section of a partial sectional view around the seat plate 2 of a fuel injector 1.
  • the seat plate 2 has a (centrally arranged) through-opening 3, which can be closed by placing an anchor element 4 on it.
  • the anchor element 4 is guided in an anchor guide 9, which allows the anchor element 4 to be moved in a targeted manner.
  • a spring element 5 typically in the form of a spiral spring, is provided, which pushes the anchor element 4 in the direction of the seat plate 2.
  • the spring element 5 is supported on an electromagnet 6, 7 and accommodates a stop 8 in the inner area of its windings, which limits the lifting movement (indicated by x) of the anchor element 4.
  • the end face 10 of the electromagnet 6, 7 facing the anchor element 4 can be In a variant of the invention, however, it can also serve as a stop.
  • reference number 11 indicates a coil casing of the coil 7, which is arranged in a recess in the magnetic core 6.
  • reference number 13 shows the axial direction of the injector.
  • the axis of symmetry 12 shows the essentially rotationally symmetrical or rotationally symmetrical basic structure of the injector.

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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)
  • Electromagnetism (AREA)
  • Fluid Mechanics (AREA)
  • Fuel-Injection Apparatus (AREA)

Description

Die vorliegende Erfindung betrifft eine Injektoreinheit zum Einspritzen von Kraftstoff sowie ein Verfahren zum Betreiben einer solchen.The present invention relates to an injector unit for injecting fuel and a method for operating such an injector unit.

In Brennkraftmaschinen wie Dieselmotoren oder auch Benzinmotoren wird in der Regel über einen Injektor Kraftstoff mit einer bestimmten Menge und für eine bestimmte Zeitdauer in einen Brennraum eingespritzt. Dabei ist es aufgrund der sehr geringen Einspritzdauern, die im Mikrosekunden-Bereich liegen, erforderlich, die Austrittsöffnung des Injektors mit einer sehr hohen Frequenz zu öffnen bzw. zu schließen.In internal combustion engines such as diesel engines or gasoline engines, fuel is usually injected into a combustion chamber via an injector in a specific quantity and for a specific period of time. Due to the very short injection durations, which are in the microsecond range, it is necessary to open and close the outlet opening of the injector at a very high frequency.

Da dem Fachmann das grundlegende Funktionsprinzip eines Injektors bekannt ist, wird nachfolgend nur kurz auf einige Aspekte eingegangen, die für das Verständnis der Erfindung von Vorteil sind.Since the basic functional principle of an injector is known to those skilled in the art, only a few aspects that are advantageous for understanding the invention will be briefly discussed below.

Ein Injektor verfügt typischerweise über eine Düsennadel (auch: Injektornadel), die einen mit einem hohen Druck beaufschlagten Kraftstoff bei Freigeben mindestens eines Austrittslochs des Injektors diesen nach außen treten lässt. Diese Düsennadel wirkt im Zusammenspiel mit dieser mindestens einen Austrittsöffnung wie ein Pfropfen, der bei einem Anheben ein Austreten des Kraftstoffs ermöglicht. Demnach ist es also erforderlich, diese Nadel in relativ kurzen Zeitabständen anzuheben und nach einer kurzen Zeit erneut in die Austrittsöffnung zurückgleiten zu lassen. Dabei können hydraulische Servoventile verwendet werden, die das Auslösen dieser Bewegung ansteuern. Solche Ventile wiederum werden mit Hilfe eines Elektromagneten angesteuert.An injector typically has a nozzle needle (also: injector needle), which allows high-pressure fuel to escape when at least one outlet hole of the injector is released. This In interaction with this at least one outlet opening, the nozzle needle acts like a plug, which allows the fuel to escape when it is raised. It is therefore necessary to lift this needle at relatively short intervals and to allow it to slide back into the outlet opening after a short time. Hydraulic servo valves can be used to trigger this movement. Such valves, in turn, are controlled with the help of an electromagnet.

Aufgrund der hohen Einspritzdrücke von bis zu 2500 bar ist es nicht möglich, die Düsennadel direkt mit Hilfe eines Magnetventils anzusteuern bzw. zu bewegen. Hierbei wäre die erforderliche Kraft zum Öffnen und Schließen der Düsennadel zu groß, so dass ein solches Verfahren nur mit Hilfe von sehr großen Elektromagneten realisierbar wäre. Eine solche Konstruktion scheidet aber aufgrund des nur beschränkt zur Verfügung stehenden Bauraums in einem Motor aus.Due to the high injection pressures of up to 2500 bar, it is not possible to control or move the nozzle needle directly using a solenoid valve. The force required to open and close the nozzle needle would be too great, so that such a process could only be implemented with the help of very large electromagnets. However, such a construction is not possible due to the limited installation space available in an engine.

Typischerweise werden anstelle der direkten Ansteuerung sogenannte Servoventile verwendet, die die Düsennadel ansteuern und selbst über ein Elektromagnetventil gesteuert werden. Dabei wird in einem mit der Düsennadel zusammenwirkenden Steuerraum mit Hilfe des unter hohen Druck zur Verfügung stehenden Kraftstoffs ein Druckniveau aufgebaut, das auf die Düsennadel in Verschlussrichtung wirkt. Dieser Steuerraum ist typischerweise über eine Zulaufleitung mit dem Hochdruckbereich des Kraftstoffs verbunden. Ferner weist dieser Steuerraum (auch: unterer Steuerraum) eine Leitung zu einem Ventilraum (auch: oberer Steuerraum) auf, der eine verschließbare Ablaufdrossel (auch Durchgangsöffnung) aufweist, aus der der unter hohem Druck stehende Kraftstoff auf der einen Seite einer Sitzplatte hin zu einem Niederdruckbereich auf der anderen Seite der Sitzplatte entweichen kann. Der Begriff Sitzplatte ist hier im Sinne einer Drosselplatte oder Dichtplatte gebraucht. Tut er dies, sinkt der Druck in dem Ventilraum und dem Steuerraum, wodurch die auf die Düsennadel wirkende Verschlusskraft verringert wird, da der unter hohem Druck stehende Kraftstoff des Ventilraums und des Steuerraums abfließen kann. Dadurch kommt es zu einer Bewegung der Düsennadel, welche die Austrittsöffnung an der Injektorspitze freigibt. Um die Bewegung der Düsennadel steuern zu können, wird die Ablaufdrossel in der Sitzplatte des Injektors mit Hilfe eines Ankerelements wahlweise verschlossen oder geöffnet.Typically, instead of direct control, so-called servo valves are used, which control the nozzle needle and are themselves controlled by an electromagnetic valve. In a control chamber that interacts with the nozzle needle, a pressure level is built up with the help of the fuel available under high pressure, which acts on the nozzle needle in the closing direction. This control chamber is typically connected to the high-pressure area of the fuel via a supply line. Furthermore, this control chamber (also: lower control chamber) has a line to a valve chamber (also: upper control chamber), which has a closable outlet throttle (also through opening) from which the high-pressure fuel can escape on one side of a seat plate to a low-pressure area on the other side of the seat plate. The term seat plate is used here in the sense of a throttle plate or sealing plate. If it does this, the pressure in the valve chamber and the control chamber drops, which reduces the closing force acting on the nozzle needle, since the high-pressure fuel in the valve chamber and the control chamber can flow out. This causes a movement of the nozzle needle, which opens the outlet opening at the injector tip In order to control the movement of the nozzle needle, the outlet throttle in the seat plate of the injector is optionally closed or opened with the help of an anchor element.

Das Ankerelement, welches die Durchgangsöffnung der Sitzplatte verschließt oder freigibt, wird mit Hilfe eines Elektromagneten betätigt. Befindet sich der Elektromagnet in einem unbestromten Zustand, ist eine bestimmte Federkraft erforderlich, die das Ankerelement gegen die Durchgangsöffnung (=Öffnung in der Sitzplatte) drückt. In einem bestromten Zustand des Elektromagneten wird das Ankerelement entgegen der von dem Federelement ausgeübte Federkraft angezogen, so dass es zu einer Stauchung der Feder kommt und das Ankerelement von der Durchgangsöffnung abgehoben wird und diese freigibt.The anchor element, which closes or opens the through hole in the seat plate, is operated using an electromagnet. If the electromagnet is not energized, a certain spring force is required to press the anchor element against the through hole (= opening in the seat plate). If the electromagnet is energized, the anchor element is attracted against the spring force exerted by the spring element, so that the spring is compressed and the anchor element is lifted from the through hole, releasing it.

Wie bereits kurz erläutert, fließt der unter hohem Druck stehende Kraftstoff also über die Durchgangsöffnung der Sitzplatte in einen Niederdruckbereich ab. Dadurch kommt es nicht nur in dem Ventilraum zu einem Druckabfall, sondern - aufgrund der den Ventilraum und den Steuerraum verbindenden Leitung- auch in dem an die Düsennadel angrenzenden Steuerraum. Die Druckverringerung in dem Steuerraum führt im Ergebnis zum Anheben der Düsennadel aus ihrem Düsensitz und zu einem Ausgeben von Kraftstoff aus dem Injektor.As already briefly explained, the high-pressure fuel flows into a low-pressure area via the through-opening of the seat plate. This results in a pressure drop not only in the valve chamber, but - due to the line connecting the valve chamber and the control chamber - also in the control chamber adjacent to the nozzle needle. The reduction in pressure in the control chamber results in the nozzle needle being raised from its nozzle seat and fuel being dispensed from the injector.

Problematisch an dem oben beschriebenen Vorgang zum Freigeben der Durchgangsöffnung ist, dass das Ankerelement aufgrund der angelegten Magnetkraft beim Öffnen gegen einen Anschlag anschlägt und an diesem prallt. Dieses sogenannte Ankerprellen an dem den Hub des Ankerelements begrenzenden Anschlag führt dazu, dass das Lösen der Düsennadel aus ihrem Düsennadelsitz und damit das Freigeben von Ausspritzöffnungen einer gewissen zeitlichen Varianz unterworfen ist. Es ist also bei einem Einspritzvorgang lediglich ein gewisser zeitlicher Bereich vorherzusagen, in dem sich die Düsennadel aus ihrem Sitz bewegen wird. Im Ergebnis führt diese zeitliche Varianz dazu, dass die Einspritzmengenregelung relativ konservativ auszulegen ist, was zu einem erhöhten Kraftstoffverbrauch führt.The problem with the process described above for releasing the through opening is that the anchor element strikes against a stop when opening due to the applied magnetic force and bounces against it. This so-called armature bouncing on the stop that limits the stroke of the armature element means that the release of the nozzle needle from its nozzle needle seat and thus the release of ejection openings is subject to a certain temporal variance. During an injection process, it is only possible to predict a certain time range in which the nozzle needle will move out of its seat. As a result, this temporal variance means that the injection quantity control must be designed relatively conservatively, which leads to increased fuel consumption.

Zudem führt das Ankerprellen zu einem Verschleiß des Ankers und des daran anschlagenden Anschlags, was zu einem vorzeitigen Austauschs eines der beiden Bauteile führen kann.In addition, armature bouncing leads to wear on the armature and the stop that abuts against it, which can lead to premature replacement of one of the two components.

Nicht zuletzt führt das Ankerprellen zudem zu einer Wärmeentwicklung der aneinander anschlagenden Teile, die eine gewisse thermische Auslegung der Bauteile und unter Umständen sogar ein Konzept zum Ableiten der thermischen Erwärmung bedingt.Last but not least, anchor bounce also leads to heat development between the parts that hit each other, which requires a certain thermal design of the components and, under certain circumstances, even a concept for dissipating the thermal heat.

Die US 2018/0030912 A1 und die DE 10 2016 222 514 A1 offenbaren dabei jeweils eine Injektoreinheit, die ein in seinem Verlauf ganz spezifisch gestuftes Ansteuersignal an den Elektromagneten führt, um das Prellen zu verringern.The US 2018/0030912 A1 and the EN 10 2016 222 514 A1 Each of them discloses an injector unit that supplies a very specifically graduated control signal to the electromagnet in order to reduce bouncing.

Es ist das Ziel der vorliegenden Erfindung eine Injektoreinheit zum Einspritzen von Kraftstoff vorzusehen, die die vorgenannten Nachteile zumindest teilweise überwindet oder abmildert. Dies gelingt mit Hilfe der Injektoreinheit, die sämtliche Merkmale des Anspruchs 1 aufweist, oder durch das Verfahren nach dem Anspruch 7.It is the aim of the present invention to provide an injector unit for injecting fuel that at least partially overcomes or mitigates the aforementioned disadvantages. This is achieved with the help of the injector unit, which has all the features of claim 1, or by the method according to claim 7.

Nach der Erfindung umfasst die Injektoreinheit zum Einspritzen von Kraftstoff unter anderem eine Sitzplatte mit einer Durchgangsöffnung, die sich durch die Sitzplatte hindurch erstreckt, ein Ankerelement, das auf die Sitzplatte aufsetzbar ist, um die Durchgangsöffnung zu verschließen, ein Federelement, das das Ankerelement in Richtung der Sitzplatte drängt, um die Durchgangsöffnung zu verschließen, einen Elektromagneten, der dazu ausgelegt ist, das Ankerelement mit einer Kraft zu beaufschlagen, um das Ankerelement von der Sitzplatte abzuheben, und einen Anschlag zum Begrenzen eines Hubs des Ankerelements in einem von der Sitzplatte abgehobenen Zustand. Die Injektoreinheit ist durch eine Steuereinheit gekennzeichnet, die dazu ausgelegt ist, ein Ansteuersignal des Elektromagneten zum Abheben des Ankerelements von der Sitzplatte zu verringern, bevor das Ankerelement den Anschlag nach einem Abheben von der Sitzplatte erstmalig kontaktiert.According to the invention, the injector unit for injecting fuel comprises, among other things, a seat plate with a through-opening that extends through the seat plate, an anchor element that can be placed on the seat plate to close the through-opening, a spring element that urges the anchor element towards the seat plate to close the through-opening, an electromagnet that is designed to apply a force to the anchor element in order to lift the anchor element off the seat plate, and a stop for limiting a stroke of the anchor element in a state lifted off the seat plate. The injector unit is characterized by a control unit that is designed to reduce a control signal of the electromagnet for lifting the anchor element off the seat plate before the Anchor element contacts the stop for the first time after lifting off the seat plate.

Dabei kann vorgesehen sein, dass das Ansteuersignal das Stromsignal ist, das durch eine Spule des Elektromagneten strömt.It can be provided that the control signal is the current signal that flows through a coil of the electromagnet.

Weiter kann vorgesehen sein, dass die Durchgangsöffnung die beiden flächigen Seiten der Sitzplatte miteinander verbindet und der auf der Sitzplatte aufgesetzt Anker die Durchgangsöffnung hydraulisch abdichtet. Weiter kann die Durchgangsöffnung eine Ablaufdrossel sein, die einen unterhalb der Sitzplatte angeordneten Raum mit einem oberhalb der Sitzplatte angeordneten Raum verbindet.Furthermore, it can be provided that the through opening connects the two flat sides of the seat plate with one another and the anchor placed on the seat plate hydraulically seals the through opening. Furthermore, the through opening can be a drain throttle which connects a space arranged below the seat plate with a space arranged above the seat plate.

Das gegenüber dem Stand der Technik überschießende Merkmal, welches in der spezifischen Form des Ansteuersignals des Elektromagneten liegt, bewirkt, dass das normalerweise auftretende Ankerprellen stark verringert oder überhaupt nicht mehr auftritt. Dies ist deswegen so, da das Ansteuersignal zum Ausüben der Magnetkraft des Elektromagneten bereits dann verringert wird, obwohl das Ankerelement noch nicht in seiner gewünschten Endposition ist. Dadurch wird die Geschwindigkeit und damit die Kraft mit der das Ankerelement auf seinen den Hub begrenzenden Anschlag auftrifft, reduziert, so dass die mit dem Ankerprellen in Verbindung stehenden Nachteile abgemildert werden können.The feature that is excessive compared to the prior art, which lies in the specific form of the control signal of the electromagnet, causes the armature bounce that normally occurs to be greatly reduced or no longer occurs at all. This is because the control signal for exerting the magnetic force of the electromagnet is already reduced even though the anchor element is not yet in its desired end position. This reduces the speed and thus the force with which the anchor element hits its stroke-limiting stop, so that the disadvantages associated with anchor bounce can be mitigated.

Um das Ankerelement aus seiner die Durchgangsöffnung abdichtenden Position abzuheben, muss die auf ihn wirkende Magnetkraft zunächst die in entgegengesetzter Richtung wirkende Federkraft und etwaige Reibungskräfte überwinden. Im Fortgang der Bewegung nimmt die anziehende Magnetkraft mit abnehmendem Abstand zwischen Ankerelement und Magnet stetig zu und das Ankerelement wird zunehmend beschleunigt, bis das Ankerelement durch den Anschlag abrupt abgebremst wird.In order to lift the anchor element from its position sealing the through opening, the magnetic force acting on it must first overcome the spring force acting in the opposite direction and any frictional forces. As the movement progresses, the attractive magnetic force increases steadily as the distance between the anchor element and the magnet decreases and the anchor element is increasingly accelerated until the anchor element is abruptly braked by the stop.

Nach der Erfindung ist vorgesehen, dass die Steuereinheit dazu ausgelegt ist, das Ansteuersignal während des Anzugs des Ankers in Richtung des Magneten mindestens einmal zu unterbrechen. Durch das Unterbrechen des Ansteuersignals wird die anziehende Magnetkraft zeitweise sehr stark reduziert. Vorteilhafterweise geschieht die Unterbrechung derart, dass sich der Anker im Anschluss aufgrund der auf ihn wirkenden Kräfte so fortbewegt, dass er mit Geschwindigkeit Null oder zumindest mit sehr geringer Geschwindigkeit am Anschlag auftrifft. Dadurch wird das Prellen vollständig verhindert oder zumindest sehr stark reduziert.According to the invention, the control unit is designed to interrupt the control signal at least once during the pull of the armature in the direction of the magnet. By interrupting the control signal, the attractive magnetic force is temporarily reduced to a very great extent. The interruption advantageously takes place in such a way that the armature subsequently moves due to the forces acting on it so that it hits the stop at zero speed or at least at a very low speed. This completely prevents the bouncing or at least greatly reduces it.

Nach einem illustrativen Beispiel ist vorgesehen, dass die Steuereinheit dazu ausgelegt ist, das Ansteuersignal des Elektromagneten um mehr als 50%, vorzugsweise mehr als 75% und bevorzugterweise mehr als 90% von einem Ausgangswert zu Beginn des Abhebevorgangs zu verringern.According to an illustrative example, it is provided that the control unit is designed to reduce the control signal of the electromagnet by more than 50%, preferably more than 75% and preferably more than 90% of an initial value at the beginning of the lifting process.

Ferner kann nach dem illustrativen Beispiel auch vorgesehen sein, dass die Steuereinheit dazu ausgelegt ist, nach einem Verringern des Ansteuersignals des Elektromagneten, das Ansteuersignal wieder anzuheben, vorzugsweise auf einen Bereich von mindestens 50%, bevorzugterweise von mindestens 75% und am bevorzugtesten von mindestens 90% eines Ausgangswerts zu Beginn des Abhebevorgangs.Furthermore, according to the illustrative example, it can also be provided that the control unit is designed to increase the control signal again after reducing the control signal of the electromagnet, preferably to a range of at least 50%, preferably of at least 75% and most preferably of at least 90% of an initial value at the beginning of the lifting process.

Nach der Erfindung kann das Ansteuersignal, welches die magnetische Anziehung des Ankerelements steuert, nur für einen kurzen Moment stark abfallen und sich kurz darauf wieder auf oder nahe dem Ausgangsniveau bewegen. Dieser kurzzeitige Einbruch des Ansteuersignals bewirkt, dass der Anker trotz des kurzzeitigen Einbruchs des Ansteuersignals von der Durchgangsöffnung wegbewegt wird. Dabei kann der kurzzeitige Abfall des Ansteuersignals so dimensioniert sein, dass es nach dem Abheben des Ankerelements von der Durchgangsöffnung nicht zu einem zwischenzeitlichen Annähern des Ankerelements in Richtung der Durchgangsöffnung kommt. Auf dem Weg von der Durchgangsöffnung hin zu dem hubbegrenzenden Anschlag kann zwar die Geschwindigkeit des Ankerelements absinken bis hin zu einem Stillstand des Ankerelements, jedoch kommt es dabei vorzugsweise nicht zu einem Annähern des Ankerelements in Richtung Durchgangsöffnung.According to the invention, the control signal, which controls the magnetic attraction of the anchor element, can only drop sharply for a short moment and shortly afterwards move back to or close to the initial level. This brief drop in the control signal causes the armature to be moved away from the through opening despite the brief drop in the drive signal. The short-term drop in the control signal can be dimensioned such that after the anchor element has been lifted off the through-opening, the anchor element does not move closer in the direction of the through-opening. On the way from the through opening to the stroke-limiting stop, the speed of the anchor element can decrease until it comes to a standstill Anchor element, but this preferably does not result in the anchor element approaching in the direction of the through opening.

Durch das so fortgebildete Ansteuersignal wird sichergestellt, dass das unerwünschte Ankerprellen an dem Anschlag verringert und eine besonders exakte Einspritzmengenregelung des Injektors erlangt wird.The control signal developed in this way ensures that the undesirable armature bounce at the stop is reduced and a particularly precise injection quantity control of the injector is achieved.

Nach der Erfindung ist vorgesehen, dass die Steuereinheit dazu ausgelegt ist, das Ansteuersignal des Elektromagneten wieder anzuheben, nachdem das Ankerelement den Anschlag erstmalig nach einem Abheben von der Sitzplatte kontaktiert hat, und/oder wenn der Hub des Ankerelements einen Umkehrpunkt erreicht oder sich zeitlich nahe des Umkehrpunktes befindet.According to the invention, it is provided that the control unit is designed to raise the control signal of the electromagnet again after the anchor element has contacted the stop for the first time after being lifted off the seat plate, and/or when the stroke of the anchor element reaches a reversal point or is close to the reversal point in time.

So kann ein Zeitpunkt zum Anheben des Ansteuersignals aus dem verringerten Niveau in Abhängigkeit einer Position des Ankerelements gewählt werden. Hier bietet es sich an, das Ansteuersignal des Elektromagneten dann zu erhöhen nachdem das Ankerelement den Anschlag erstmalig nach einem Abheben von der Sitzplatte kontaktiert hat, und/oder wenn der Hub des Ankerelements einen Umkehrpunkt erreicht. Anderenfalls kommt es zu einer ungewollten Bewegung des Ankerelements in Richtung der Dichtungsöffnung.In this way, a point in time for raising the control signal from the reduced level can be selected depending on the position of the armature element. In this case, it is advisable to increase the control signal of the electromagnet after the armature element has contacted the stop for the first time after lifting off the seat plate and/or when the stroke of the armature element reaches a reversal point. Otherwise, the armature element will move in the direction of the seal opening inadvertently.

Nach der Erfindung ist vorgesehen, dass die Steuereinheit dazu ausgelegt ist, das Ansteuersignal auf binäre Art und Weise, also nur die Ansteuersignalzustände An und Aus zu übermitteln. Für die Auslegung und Steuerung der erfindungsgemäßen Einheit ist es von Vorteil, wenn das Ansteuersignal lediglich zwei Zustände, nämlich An und Aus einnehmen kann.According to the invention it is provided that the control unit is designed to transmit the control signal in a binary manner, i.e. only the control signal states on and off. For the design and control of the unit according to the invention, it is advantageous if the control signal can only assume two states, namely on and off.

Dann wird das Ansteuersignal während eines Anhebevorgangs des Ankerelements nach einer An-Periode deaktiviert bzw. vorübergehend deaktiviert. Dies führt zu einem insgesamt vorteilhafteren Anhebevorgang, der ein geringeres Ankerprellen aufweist.Then, during a lifting process of the armature element, the control signal is deactivated or temporarily deactivated after an on period. This leads to an overall more advantageous lifting process that has less armature bounce.

Vorzugsweise kann vorgesehen sein, dass die Sitzplatte in einem geschlossenen Zustand der Durchgangsdrossel dazu ausgelegt ist, einen Niederdruckbereich und einen Hochdruckbereich des Kraftstoffs zu trennen.Preferably, it can be provided that the seat plate is designed to separate a low-pressure area and a high-pressure area of the fuel when the through-throttle is closed.

Nach einer weiteren Modifikation der Erfindung kann vorgesehen sein, dass der Raum, der zum Ausführen des Hubs des Ankerelements vorgesehen ist, mit einem Fluid, vorzugsweise dem Kraftstoff gefüllt ist. Das Fluid ist dabei nicht oder nur schwach magnetisierbar.According to a further modification of the invention, it can be provided that the space provided for carrying out the stroke of the anchor element is filled with a fluid, preferably the fuel. The fluid is not or only weakly magnetizable.

Ferner kann eine Ankerführung zum Führen des Ankerelements bei einem Hubvorgang vorgesehen sein, die sich vorzugsweise von der Sitzplatte in Richtung des Anschlags erstreckt. Diese Führung dient zum gezielten Aufsetzen bzw. Abheben des Ankerelements von der Durchgangsöffnung der Sitzplatte.Furthermore, an anchor guide can be provided for guiding the anchor element during a lifting process, which preferably extends from the seat plate in the direction of the stop. This guide serves for the targeted placement or lifting of the anchor element from the through opening of the seat plate.

Es kann nach der Erfindung vorgesehen sein, dass der Elektromagnet einen Magnetkern und eine Spule aufweist, die den Magnetkern teilweise oder vollständig aufnimmt.According to the invention, it can be provided that the electromagnet has a magnetic core and a coil which partially or completely accommodates the magnetic core.

Vorzugsweise kann der Anschlag eine Stirnfläche des Elektromagneten sein oder auch eine Stirnfläche eines Magnetkerns des Elektromagneten. Von der Erfindung ist aber auch der Fall umfasst, dass der Anschlag kein Teil des Elektromagneten ist.Preferably, the stop can be an end face of the electromagnet or also an end face of a magnetic core of the electromagnet. However, the invention also includes the case that the stop is not part of the electromagnet.

Vorzugsweise ist der Anschlag jedoch im Inneren des als Spiralfeder ausgebildeten Federelements vorgesehen, so dass sich die Spiralfeder um den Anschlag herum windet.Preferably, however, the stop is provided inside the spring element designed as a spiral spring, so that the spiral spring winds around the stop.

Die Erfindung betrifft zudem ein Verfahren zum Betreiben einer Injektoreinheit zum Einspritzen von Kraftstoff, die vorzugsweise nach einem der vorhergehenden Varianten ausgestaltet ist, wobei in dem Verfahren unter anderem ein Ankerelement von einer Sitzplatte entgegen einer durch eine Feder ausgeübte Federkraft in Richtung der Sitzplatte mittels eines Elektromagneten abgehoben wird, um eine Durchgangsöffnung der Sitzplatte freizugeben. Das Verfahren zeichnet sich dadurch aus, dass das Ansteuersignal des Elektromagneten, das ein Abheben des Ankerelements von der Sitzplatte bewirkt, verringert wird, bevor das Ankerelement einen den Hub des Ankerelements begrenzenden Anschlag nach einem Abheben von der Sitzplatte erstmalig kontaktiert.The invention also relates to a method for operating an injector unit for injecting fuel, which is preferably designed according to one of the preceding variants, wherein in the method, among other things, an anchor element is moved from a seat plate against a spring force exerted by a spring in the direction of the seat plate by means of an electromagnet picked up to release a through opening in the seat plate. The method is characterized in that the control signal of the electromagnet, which causes the anchor element to be lifted off the seat plate, is reduced before the anchor element contacts a stop limiting the stroke of the anchor element for the first time after it has been lifted off the seat plate.

Nach einem illustrativen Beispiel kann vorgesehen sein, dass das Ansteuersignal des Elektromagneten um mehr als 50%, vorzugsweise mehr als 75% und bevorzugterweise mehr als 90% von einem Ausgangswert zu Beginn des Abhebevorgangs verringert wird.According to an illustrative example, it can be provided that the control signal of the electromagnet is reduced by more than 50%, preferably more than 75% and preferably more than 90% from an initial value at the beginning of the lifting process.

Weiter kann nach diesem illustrativen Beispiel vorgesehen sein, dass nach einem Verringern des Ansteuersignals des Elektromagneten, das Ansteuersignal wieder angehoben wird, vorzugsweise auf einen Bereich von mindestens 50%, bevorzugterweise von mindestens 75% und am bevorzugtesten von mindestens 90% eines Ausgangswerts zu Beginn des Abhebevorgangs.Furthermore, according to this illustrative example, it can be provided that after reducing the control signal of the electromagnet, the control signal is increased again, preferably to a range of at least 50%, preferably of at least 75% and most preferably of at least 90% of an initial value at the beginning of the lifting process.

Dabei kann nach der Erfindung vorgesehen sein, dass das Ansteuersignal des Elektromagneten wieder angehoben wird, nachdem das Ankerelement den Anschlag erstmalig nach einem Abheben von der Sitzplatte kontaktiert hat, und/oder wenn der Hub des Ankerelements einen Umkehrpunkt erreicht oder nahe zu seinem Umkehrpunkt ist.According to the invention, it can be provided that the control signal of the electromagnet is raised again after the anchor element has contacted the stop for the first time after being lifted off the seat plate, and/or when the stroke of the anchor element reaches a reversal point or is close to its reversal point.

Nach dem erfindungsgemäßen Verfahren ist zudem vorgesehen, dass das Ansteuersignal binärer Natur ist, also nur die Ansteuersignalzustände An und Aus an den Elektromagneten übermittelt werden.According to the method according to the invention it is also provided that the control signal is of a binary nature, i.e. only the control signal states on and off are transmitted to the electromagnet.

Weitere Einzelheiten, Merkmale und Vorteile der Erfindung werden anhand der nachfolgenden Figurenbeschreibung ersichtlich. Dabei zeigen:

Fig. 1:
ein Diagramm zur Darstellung des Ansteuersignals nach der Erfindung gegenüber dem Stand der Technik, und
Fig. 2:
einen vergrößerten Ausschnitt einer teilweisen Schnittansicht um die Sitzplatte eines Kraftstoffinjektors herum.
Further details, features and advantages of the invention will become apparent from the following description of the figures.
Fig.1:
a diagram showing the control signal according to the invention compared to the prior art, and
Fig. 2:
an enlarged detail of a partial sectional view around the seat plate of a fuel injector.

Fig. 1 zeigt zwei übereinander angeordnete Diagramme über die Zeit t, wobei das obere der beiden Diagramme den Verlauf eines Ansteuersignals I, bzw. des an den Elektromagneten zugeführten Stroms nach der Erfindung (durchgezogene Linie A) und nach dem Stand der Technik (gestrichelte Linie B) zeigt. Das darunter angeordnete Diagramm zeigt die Bewegung (x) des Ankerelements in Abhängigkeit des verschiedenen Ansteuersignale, wobei die gestrichelte Linie das Ansteuerverhalten nach dem Stand der Technik und die durchgehende Linie die erfindungsgemäße Ansteuerung darstellt. Fig. 1 shows two diagrams arranged one above the other over time t, the upper of the two diagrams showing the course of a control signal I or the current supplied to the electromagnet according to the invention (solid line A) and according to the prior art (dashed line B). . The diagram below shows the movement (x) of the anchor element as a function of the various control signals, with the dashed line representing the control behavior according to the prior art and the solid line representing the control according to the invention.

Den Diagrammen kann man entnehmen, dass zum Zeitpunkt t0 das Ankerelement auf der Sitzplatte aufliegt, so dass die Durchgangsöffnung abgedichtet ist.From the diagrams it can be seen that at time t 0 the anchor element rests on the seat plate so that the through hole is sealed.

Setzt man nun zum Zeitpunkt t0 das Stromsignal I zum Ansteuern des Elektromagneten auf einen Wert I1, der von Null verschieden ist und dazu führt, dass das Ankerelement von der Sitzplatte in Richtung eines hubbegrenzenden Anschlags bewegt wird, bewegt sich das Ankerelement zunächst langsam und dann mit immer schnellerer Geschwindigkeit in Richtung des Anschlags (vgl. gestrichelte Linie B). Dabei nimmt die anziehende Magnetkraft mit abnehmendem Abstand zwischen Anker und Elektromagnet stetig zu und das Ankerelement wird zunehmend beschleunigt, bis das Ankerelement durch einen Anschlag abrupt abgebremst wird (Xstop). Dabei kommt es nachfolgend zu einem ausgeprägten Prellverhalten des Ankers am Anschlag. Das Prellen wirkt sich negativ auf die Einstellbarkeit des Magnetventils sowie die Rückkoppelung auf das hydraulische Schaltverhalten aus und erhöht den Verschleiß an dem Magnet und dem Ankerelement.If, at time t 0, the current signal I for controlling the electromagnet is set to a value I 1 that is different from zero and causes the anchor element to be moved from the seat plate in the direction of a stroke-limiting stop, the anchor element initially moves slowly and then at ever faster speed in the direction of the stop (see dashed line B). The attractive magnetic force increases steadily as the distance between the armature and the electromagnet decreases and the armature element is increasingly accelerated until the armature element is abruptly braked by a stop (X stop ). This results in a pronounced bouncing behavior of the anchor at the stop. The bouncing has a negative effect on the adjustability of the solenoid valve as well as the feedback on the hydraulic switching behavior and increases wear on the magnet and the anchor element.

Nach Abschluss des Prellens verharrt das Ankerelement an seinem Anschlag in der von der Durchgangsöffnung entfernten Position, bis das Ansteuersignal I1 zum Zeitpunkt t3 abgeschaltet wird. Dann wird der Stromfluss durch die Spule vollständig abgebaut und das Magnetfeld bildet sich zurück, wobei ein Teil des magnetischen Feldes aufgrund von Remanenzeffekten und Wirbelstromeinflüssen für eine kurze Zeit erhalten bleibt. Sobald die nachlassende magnetische Kraft die Federkraft nicht mehr überwindet, wird der Anker von der Feder zurück auf die Sitzplatte gedrückt.After bouncing has ended, the armature element remains at its stop in the position away from the through hole until the control signal I 1 is switched off at time t 3 . The current flow through the coil is then completely reduced and the magnetic field is restored, with part of the magnetic field remaining for a short time due to remanence effects and eddy current influences. As soon as the decreasing magnetic force no longer overcomes the spring force, the armature is pressed back onto the seat plate by the spring.

Problematisch ist hieran das Prellen bei der maximalen Auslenkung des Ankerelements bei der Distanz Xstop.The problem here is the bouncing at the maximum deflection of the anchor element at the distance X stop .

Mit einem verbesserten Ansteuersignal nach der Erfindung soll das Prellen des Ankers am von der Sitzplatte beabstandeten Anschlag Xstop verhindert oder zumindest stark verringert werden. Dafür ist nach der Erfindung vorgesehen, das Ansteuersignal während des Anzugs des Ankers in Richtung des Anschlags bzw. des Magneten mindestens einmal zu unterbrechen oder zu verringern.With an improved control signal according to the invention, the bouncing of the armature at the stop X stop , which is spaced from the seat plate, should be prevented or at least greatly reduced. For this purpose, according to the invention, the control signal is interrupted or reduced at least once while the armature is being pulled in the direction of the stop or the magnet.

Nachdem zum Zeitpunkt t0 - genau wie nach dem Stand der Technik - das Stromsignal I zum Ansteuern des Elektromagneten auf den Wert I1 gesetzt worden ist, beginnt sich das Ankerelement von der Sitzplatte in Richtung des Anschlags zu bewegen.After the current signal I for controlling the electromagnet has been set to the value I 1 at time t 0 - exactly as in the state of the art - the armature element begins to move from the seat plate in the direction of the stop.

Erfindungsgemäß ist nun aber vorgesehen, das Ansteuersignal bereits vor einem Kontakt des Ankerelements mit dem Anschlag zu verringern oder wie in Fig. 1 dargestellt auf null zurückzusetzen. Hierdurch wird die anziehende Magnetkraft zeitweise sehr stark reduziert, so dass sich der Anker im Anschluss aufgrund der auf ihn wirkenden Kräfte derart fortbewegt, dass er mit Geschwindigkeit Null oder zumindest mit sehr geringer Geschwindigkeit am oberen Anschlag auftrifft. Dadurch wird das Prellen vollständig verhindert oder zumindest sehr stark reduziert.According to the invention, however, it is now provided that the control signal is reduced before the anchor element comes into contact with the stop, or as in Fig. 1 shown to reset to zero. As a result, the attractive magnetic force is temporarily greatly reduced, so that the armature then moves due to the forces acting on it in such a way that it hits the upper stop at zero speed or at least at very low speed. This completely prevents bouncing or at least greatly reduces it.

Im Idealfall wird das Ansteuersignal wieder aktiviert (letzte Ansteuersignalaktivierung zum Zeitpunkt t2), sobald der Anker auf den zweiten Anschlag mit Geschwindigkeit Null oder nahe Null trifft, so dass der Anker im Anschlag gehalten wird, bis das Ansteuersignal letztlich beendet wird (Zeitpunkt ts). Von der Erfindung ist jedoch auch der Fall umfasst, wonach der Anker den Anschlag entweder nicht oder mit einer Geschwindigkeit größer Null erreicht. Das Ansteuersignal wird vorteilhafterweise dann wieder in einem zeitlichen Bereich aktiviert, in dem die Ankergeschwindigkeit nahe Null ist (Zeitpunkt ts). Das Prellen kann dabei nicht vollständig unterdrückt werden, wird jedoch im Vergleich zur konventionellen Ansteuerung signifikant verringert.Ideally, the control signal is activated again (last control signal activation at time t 2 ) as soon as the armature hits the second stop at zero or close to zero speed, so that the armature is held in the stop until the control signal is finally terminated (time ts). However, the invention also covers the case where the armature either does not reach the stop or does so at a speed greater than zero. The control signal is then advantageously activated again in a time range in which the armature speed is close to zero (time ts). The bouncing cannot be completely suppressed in this case, but is significantly reduced compared to conventional control.

Ist es nicht mehr länger gewünscht, dass das Ankerelement die Durchgangsöffnung der Sitzplatte freigibt, wird zum Zeitpunkt t3 das Ansteuersignal deaktiviert, wodurch das Ankerelement durch das Federelement in Richtung der Sitzplatte gedrängt wird und dort - ähnlich wie am von der Sitzplatte beabstandeten Anschlag bei einer Bestromung des Elektromagneten nach dem Stand der Technik - prallt.If it is no longer desired that the anchor element releases the through opening of the seat plate, the control signal is deactivated at time t 3 , whereby the anchor element is pushed by the spring element in the direction of the seat plate and there - similar to the stop spaced from the seat plate in a Current supply to the electromagnet according to the state of the art - bounces.

Fig. 2 zeigt einen vergrößerten Ausschnitt einer teilweisen Schnittansicht um die Sitzplatte 2 eines Kraftstoffinjektors 1 herum. Fig.2 shows an enlarged section of a partial sectional view around the seat plate 2 of a fuel injector 1.

Die Darstellung ist nur auf einer Seite der Symmetrieachse 12 dargestellt. Am unteren Ende der Darstellung erkennt man, dass die Sitzplatte 2 eine (mittig angeordnete) Durchgangsöffnung 3 aufweist, die durch das Aufsetzen eines Ankerelements 4 verschlossen werden kann. Das Ankerelement 4 ist dabei in einer Ankerführung 9 geführt, die ein zielgerichtetes Bewegen des Ankerelements 4 erlaubt. Oberhalb des Ankerelements 4, also an der zur Sitzplatte 2 abgewandten Seite des Ankerelements 4, ist ein Federelement 5, typischerweise in Form einer Spiralfeder, vorgesehen, das das Ankerelement 4 in Richtung der Sitzplatte 2 drängt. Das Federelement 5 stützt sich dabei an einem Elektromagneten 6, 7 ab und nimmt im Innenbereich seiner Windungen einen Anschlag 8 auf, der die Hubbewegung (angedeutet mit x) des Ankerelements 4 begrenzt. Die dem Ankerelement 4 zugewandte Stirnseite 10 des Elektromagneten 6, 7 kann nach einer Variante der Erfindung aber auch als Anschlag dienen. Zudem erkennt man mit dem Bezugszeichen 11 eine Spulenummantelung der Spule 7, die in einer Ausnehmung des Magnetkerns 6 angeordnet ist. Weiter zeigt das Bezugszeichen 13 die axiale Richtung des Injektors.The illustration is only shown on one side of the axis of symmetry 12. At the lower end of the illustration, it can be seen that the seat plate 2 has a (centrally arranged) through-opening 3, which can be closed by placing an anchor element 4 on it. The anchor element 4 is guided in an anchor guide 9, which allows the anchor element 4 to be moved in a targeted manner. Above the anchor element 4, i.e. on the side of the anchor element 4 facing away from the seat plate 2, a spring element 5, typically in the form of a spiral spring, is provided, which pushes the anchor element 4 in the direction of the seat plate 2. The spring element 5 is supported on an electromagnet 6, 7 and accommodates a stop 8 in the inner area of its windings, which limits the lifting movement (indicated by x) of the anchor element 4. The end face 10 of the electromagnet 6, 7 facing the anchor element 4 can be In a variant of the invention, however, it can also serve as a stop. In addition, reference number 11 indicates a coil casing of the coil 7, which is arranged in a recess in the magnetic core 6. Furthermore, reference number 13 shows the axial direction of the injector.

Die Symmetrieachse 12 zeigt dabei den im Wesentlichen drehsymmetrischen oder rotationssymmetrischen Grundaufbau des Injektors.The axis of symmetry 12 shows the essentially rotationally symmetrical or rotationally symmetrical basic structure of the injector.

Claims (7)

  1. An injector unit (1) for injecting fuel comprising:
    a seat plate (2) having a passage opening (3) that extends through the seat plate (2);
    an armature element (4) that is placeable onto the seat plate (2) to close the passage opening (3);
    a spring element (5) that urges the armature element (4) in the direction of the seat plate (2) to close the passage opening (3);
    an electromagnet (6, 7) that is configured to apply a force onto the armature element (4) to raise the armature element (4) from the seat plate (2); and
    an abutment (8) for bounding a stroke (x) of the armature element (4) in a state raised from the seat plate (2), wherein
    a control unit that is configured to reduce a control signal of the electromagnet (6, 7) to raise the armature element (4) from the seat plate (2) before the armature element (4) contacts the abutment (8) for the first time after a raising from the seat plate (2).,
    characterized in that
    the control unit is configured to interrupt the control signal of the electromagnet (6, 7) even though the armature element (4) is not yet in its desired end position; and
    the control unit is configured to raise the control signal back to its starting value at the start of the raising procedure after an interruption of the control signal of the electromagnet (6, 7) after the armature element (4) has contacted the abutment (8) for the first time after a raising from the seat plate (2) and/or when the stroke of the armature element (4) reaches a reversal point or is close thereto in time, with the control unit being configured to transmit the control signal in a binary manner, that is only to transmit the control signal states On and Off.
  2. An injector unit (1) in accordance with one of the preceding claims, wherein the seat plate (2) is configured in a closed state of the passage throttle to separate a low pressure region and a high pressure region of the fuel.
  3. An injector unit (1) in accordance with one of the preceding claims, wherein the space that is provided for the carrying out of the stroke (x) of the armature element (4) is filled with a fluid, preferably the fuel.
  4. An injector unit (1) in accordance with one of the preceding claims, wherein an armature guide (9) is furthermore provided to guide the armature element (4) on a stroke procedure, said armature guide (9) preferably extending from the seat plate (2) in the direction of the abutment (8).
  5. An injector unit (1) in accordance with one of the preceding claims, wherein the electromagnet (6,, 7) has a magnetic core and a coil that partially or completely receives the magnetic core.
  6. An injector unit (1) in accordance with one of the preceding claims, wherein the abutment (8) is a front surface (11) of the electromagnet (6, 7), preferably a front surface (11) of a magnetic core (6) of the electromagnet (6, 7).
  7. A method of operating an injector unit (1) for injecting fuel that is preferably designed in accordance with one of the preceding claims, wherein, in the method,
    an armature element (4) is raised from a seat plate (2) against a spring force exerted by a spring element (5) in the direction of the seat plate (2) by means of an electromagnet (6, 7) to release a passage opening (3) of the seat plate (2), and
    the control signal of the electromagnet (6, 7), that effects a raising of the armature element (4) from the seat plate (2), is reduced before the armature element (4) contacts an abutment (8) that bounds the stroke of the armature element (4) for the first time after a raising from the seat plate (2),
    characterized in that
    the control signal of the electromagnet (6, 7) is interrupted even though the armature element (4) is not yet in its desired end position; and
    the control signal is raised back to its starting value at the start of the raising procedure after an interruption of the control signal of the electromagnet (6, 7) after the armature element (4) has contacted the abutment (8) for the first time after a raising from the seat plate (2) and/or when the stroke of the armature element (4) reaches a reversal point or is close thereto in time, with
    the control signal being of a binary nature, that is only the control signal states On and Off are transmitted.
EP20705636.7A 2019-02-11 2020-02-11 Injector unit for the injection of fuel, and method for the operation of an injector unit of this type Active EP3921536B1 (en)

Applications Claiming Priority (2)

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DE102019103362.4A DE102019103362A1 (en) 2019-02-11 2019-02-11 Injector unit for injecting fuel and method for operating such
PCT/EP2020/053395 WO2020165126A1 (en) 2019-02-11 2020-02-11 Injector unit for the injection of fuel, and method for the operation of an injector unit of this type

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EP3921536A1 EP3921536A1 (en) 2021-12-15
EP3921536B1 true EP3921536B1 (en) 2024-04-03

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US (1) US20220186698A1 (en)
EP (1) EP3921536B1 (en)
CN (1) CN113454331B (en)
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Publication number Priority date Publication date Assignee Title
DE102022131385A1 (en) 2022-11-28 2024-05-29 Liebherr-Components Deggendorf Gmbh Injector for injecting fuel

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3545676A (en) * 1966-10-17 1970-12-08 Monsanto Co Temperature control system
IT220662Z2 (en) * 1990-10-31 1993-10-08 Elasis Sistema Ricerca Fita Nel Mezzogiorno Soc.Consortile P.A. IMPROVEMENTS TO THE PILOT VALVE AND TO THE RELATED STILL OF ORDER AN ELECTROMAGNETIC INJECTOR FOR FUEL INJECTION SYSTEMS OF INTERNAL COMBUSTION ENGINES
US5626325A (en) * 1995-09-14 1997-05-06 Cummins Engine Company, Inc. High pressure control valve for a fuel injection system
WO2015071686A1 (en) * 2013-11-15 2015-05-21 Sentec Ltd Control unit for a fuel injector
WO2015143116A1 (en) * 2014-03-20 2015-09-24 GM Global Technology Operations LLC Alternating current drive for actuators
DE102014224321A1 (en) * 2014-11-27 2016-06-02 Robert Bosch Gmbh Method for determining the armature stroke of a magnetic actuator
DE102015206729A1 (en) * 2015-04-15 2016-10-20 Continental Automotive Gmbh Controlling a fuel injection solenoid valve
DE102015208573B3 (en) * 2015-05-08 2016-06-16 Continental Automotive Gmbh Pressure determination in a fuel injection valve
DE102016220912A1 (en) * 2016-10-25 2018-04-26 Robert Bosch Gmbh Fuel injection valve
DE102016222514A1 (en) * 2016-11-16 2018-05-17 Robert Bosch Gmbh Method for controlling a solenoid valve of a fuel injector

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CN113454331A (en) 2021-09-28
US20220186698A1 (en) 2022-06-16
DE102019103362A1 (en) 2020-08-13
WO2020165126A1 (en) 2020-08-20
CN113454331B (en) 2024-07-12
EP3921536A1 (en) 2021-12-15

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